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RESEARCH

Nordenetal. Geothermal Energy (2023) 11:1

https://doi.org/10.1186/s40517-022-00242-2

Geothermal Energy

From pilot knowledge viaintegrated

reservoir characterization toutilization

perspectives ofdeep geothermal reservoirs:

the3D model ofGroß Schönebeck (North

German Basin)

Ben Norden1* , Klaus Bauer1 and Charlotte M. Krawczyk1,2

Abstract

The Groß Schönebeck site in the North German Basin serves as research platform to

study the geothermal potential of deeply buried Permian reservoir rocks and the tech-

nical feasibility of heat extraction. The structural setting of the site was investigated in

more detail by a newly acquired 3D-seismic survey to improve the former conceptual

model that was based on several old 2D seismic lines. The new data allow a revision of

the geological interpretation, enabling the setup of a new reservoir model and provid-

ing base information for a possible further site development of Permo-Carboniferous

targets. The 3D seismic allows for the first time a consistent geological interpreta-

tion and model parameterization of the well-studied geothermal site. Main reflector

horizons and the corresponding stratigraphic units were mapped and the structural

pattern of the subsurface presented in the 8 km × 8 km × 4 km large seismic volume.

Attribute analysis revealed some fracture and fault patterns in the upper Zechstein and

post-Permian units, while formerly hypothesized large offset faults are not present in

the Rotliegend reservoir. However, a well-established graben-like structure at the top

of the Zechstein succession is most likely related to broken anhydritic brittle intra-salt

layers of some meter of thickness. Most reflectors above the salt show a rather undis-

turbed pattern. The main reservoir sandstone of the Dethlingen Formation (Rotliegend)

was mapped and characterized. The base of the underlying Permo-Carboniferous

volcanic rock sequence and hence its thickness could not be depicted reliably from the

geophysical data. Based on the seismic data and the available reconnaissance drilling,

logging, and laboratory data of the Groß Schönebeck research site, the thickness and

distribution of the sedimentary Rotliegend (with emphasis of the sandy reservoir sec-

tion) and of the volcanic rock sequence was modelled and stochastically parameter-

ized with petrophysical properties guided by seismic facies pattern correlation, provid-

ing a more realistic reservoir description. Properties include total and effective porosity,

permeability, bulk density, thermal conductivity, thermal diffusivity, and specific heat

capacity. The data and interpretation constitute the basis for a better understanding of

the thermo and hydromechanical processes at the site and for future measures. Further

*Correspondence:

[email protected]

1 GFZ German Research Centre

for Geosciences, Telegrafenberg,

14473 Potsdam, Germany

2 TU Berlin, Institute for Applied

Geosciences, Ernst-Reuter-Platz

1, 10587 Berlin, Germany

Page 2 of 44

Nordenetal. Geothermal Energy (2023) 11:1

site development could include a deepening of one well to provide evidence on the

volcanic rock sequence and consider deviated wells into favourable zones and the

design of a fracture-dominated utilization approach.

Keywords: Groß Schönebeck, 3D geological modelling, Petrophysical

parameterization, Site development, Permian, Elbe reservoir, Permo-Carboniferous

volcanic rocks

Introduction

The planning of the overall exploitation concept for low-enthalpy geothermal resources

strongly depends on both regional and local geology and includes the drill path design

(directional drilling, deviation) and stimulation operations in case of low-productive

reservoirs (e.g., von Hartmann etal. 2015; Kana etal. 2015; Ricard etal. 2016). For

the development of an adequate (site-specific) exploitation strategy, knowledge on the

existence and orientation of large-scale faults, fracture networks and of a possible com-

partmentalization of target horizons are of utmost importance (c.f., Buness etal. 2014;

Krawczyk etal. 2015). Imaging these structural features at depth and including this

knowledge in reservoir models greatly expands the basis for an efficient use of geother-

mal energy (e.g., Bauer etal. 2010; McGuire etal. 2015).

Among the sedimentary basins worldwide that contain deep geothermal resources

(Mendrinos etal. 2010; Pussak etal. 2014; Siler etal. 2016; Zhang and Hu 2018), the

North German Basin is one of the three type locations in Germany that offers potential

for geothermal heat production. At the Groß Schönebeck research platform, reconnais-

sance boreholes and vintage 2D seismic lines were lately supplemented by 3D reflection

seismic (Krawczyk etal. 2019) and VSP (Henninges etal. 2021; Martuganova etal. 2022)

surveys, which provide the basis of the new geological and reservoir model presented in

this manuscript.

We address the development of a new site model for the Groß Schönebeck geothermal

research platform that shows how already existing knowledge and adapted procedures

can help developing a site for geothermal use. For the North German Basin type lith-

ologies, covering Carboniferous to Cenozoicunits, we provide reservoir model param-

eterization of the Permo-Carboniferous target zones that are important for future deep

geothermal development. The knowledge and the data sets gained at Groß Schönebeck

will also help planning exploitation concepts for comparable geological settings.

Summary ofoperational site development atGroß‑Schönebeck

The research platform Groß Schönebeck is located 40km north of Berlin (Fig.1) and

was established over the last two decades. The target horizons for geothermal utilization

were the sedimentary Permian and the Permo-Carboniferous volcanic rocks, hosting in-

situ temperatures of about 150°C. The site development started with the re-opening of

a non-successful 4.2-km-deep hydrocarbon exploration well in 2001 (the E GrSk 3/90

well, which was drilled in 1990) and was followed by initial hydraulic tests and the drill-

ing of a new geothermal research well (the Gt GrSk 4/05 borehole, completed in 2006

as production well). Hydraulic stimulations were performed to increase the fluid inflow

to the Gt GrSk 4/05 borehole. Further tests including the installation and operation of a

Page 3 of 44

Nordenetal. Geothermal Energy (2023) 11:1

geothermal loop followed. The pumping of the high-saline reservoir fluids successively

depicted obstacles which hindered a lasting operation of the geothermal loop and thus

the commissioning of a heat conversion plant (see summary in Blöcher etal. 2016).

So far, the geothermal exploitation concept relied on a matrix-dominated approach,

and sparsely distributed 2D seismic profiles (acquired in 1987, Fig.1, Table1) were used

to set up a first 3D geological model of the Groß Schönebeck area, forming the base of

the first exploitation concept and the well design of the Gt GrSk 4/05 borehole (Moeck

etal. 2009). To conclude, the experiences made with this concept were not successful.

As an alternative, a concept based on an engineered fracture-dominated exploitation

approach for establishing a continuous and sustainable geothermal loop came into dis-

cussion. To exclude any structural obstacles, a 3D seismic exploration campaign was per-

formed to shed light into the detailed structural setting of the site. The processing and

a first rough interpretation of these data are provided in Krawczyk etal. (2019), while

the detailed geological interpretation of the seismic data is part of this paper. The first

time determinants for further field development at the site could be identified: formerly

hypothesized crustal-scale faults, indications for free gas, seismic compartmentalization

in the sub-salinar, and a fracture-dominated Rotliegend reservoir were all not proven

Fig. 1 Site map of Northeast Brandenburg showing the 3D seismic of the Groß Schönebeck study area (red

rectangle), the location of former 2D seismic reconnaissance lines (LEW; blue lines), the location of deep

boreholes, the distribution of the Permo-Carboniferous volcanic rock associations after Benek et al. (1996),

the Permo-Carboniferous succession as encountered in two boreholes (E Ob 1/68 and E GrSk 3/90 based on

drilling reports, for legend see Fig. 2), the distribution of salt pillows (blue areas) in the subsurface according

to the Northwest-European Gas Atlas (Lokhorst 1998), and main roads and towns (33UTM-WGS84 projection).

For orientation, an overview map shows the distribution of Rotliegend sediments (grey shaded) and the

location of the study area (stippled rectangle). NGB North German Basin, PT Polish Trough

Page 4 of 44

Nordenetal. Geothermal Energy (2023) 11:1

(Krawczyk etal. 2019). Rather, the seismic facies diversity of the reservoir target units,

deduced from a seismic attribute study (Bauer etal. 2020), leads to the interpretation

of a system of thicker paleo-channels deposited within a deepened landscape, allowing

large-scale thickness variations.

These findings influence the geothermal exploitation concept, so that we present here

an in-depth reservoir investigation of the structural setting, including the interpreta-

tion of seismic horizons, involved fault systems, and a more complex, geologically based

(facies-driven) distribution of petrophysical properties for the reservoir targets.

Geological setting

The Groß Schönebeck deep geothermal research platform is located in the North Ger-

man Basin (NGB) which is part of the Central European Basin System reaching from

Middle England to North Germany, Poland and the Baltic States (Fig.1; Ziegler 1990;

Doornenbal and Stevenson 2010), reflecting a low-enthalpy geothermal setting. The

basin developed in the late Carboniferous and early Permian in response to thermal

relaxation, crustal extension and tectonic subsidence (van Wees etal. 2000). The sub-

sequent sedimentation resulted in the deposition of sedimentary rocks with a thickness

of up to 6.500m in the eastern part of the NGB (Hoth etal. 1993; DEKORP-BASIN

Research Group 1999). The NGB was like other sub basins of the Permian Basin System

a target area for the hydrocarbon industry. Several seismic campaigns and deep drillings

were performed to investigate the most prospective target zones, like the Permian Rotli-

egend sediments, also in northeast Brandenburg (Fig.1). The geological evolution of the

basin and its lithological composition will be summarized shortly in the following.

Pre‑Permian basement andPermo‑Carboniferous volcanic rocks

In the study area (Fig.1), details on the Carboniferous and pre-Carboniferous base-

ment are not well constrained. Devonian rocks are proven to be partly absent in the

Table 1 Data used in this paper

For location of boreholes see Fig.1

Abbreviations of different processed seismic volumes: PoSTM post-stack time migration, NMO normal move out, CRS

common reflection surface, PreSDM pre-stack depth migration, DeMultiple suppression of seismic multiples

Kind of data Name(s) References

Boreholes—stratigraphy and main

lithology E Ob 1/68, E GrSk 2/67, E GrSk 3/90,

Gt GrSk 4/05 drilling reports, partly published in:

Hoth et al. (1993), Rockel and Hurter

(2000), Holl et al. (2005)

Boreholes—petrophysical rock

analysis (cores) E GrSk 3/90 Rockel and Hurter (2000), Trautwein

(2005), Blöcher et al. (2016), Lotz

(2004), this paper

Boreholes—geophysical well

logging E GrSk 3/90, Gt GrSk 4/05 Huenges and Hurter (2002), Huenges

and Winter (2004)

2D seismic FIW–LEW: Finowfurt–Liebenwalde

campaign, acquired in 1987 König and Meyer (1988); this paper

DAS–VSP data of Groß Schönebeck Different lines and volumes Martuganova et al. (2022)

3D seismic of Groß Schönebeck PoSTM, NMO Stack, CRS-Stack, CRS-

PoSTM, PreSDM-DeMultiple (in time

and depth domain)

Acquisition in Krawczyk et al. (2019);

interpretation: this paper

Page 5 of 44

Nordenetal. Geothermal Energy (2023) 11:1

sedimentary succession (Bełka etal. 2010) and are indeed not drilled by any deep bore-

hole in Brandenburg (Franke 2015a), although they may be expected in depths of more

than 6–7km. Maximum drilled depths to about 5.2km give evidence of Lower Carbon-

iferous (Dinantian) rocks in Brandenburg. The rocks encountered consist of fine-grained

to coarse-grained greywacke, siltstones and pelites of a distal to proximal flysch facies

type (Kopp etal. 2004; Kombrink etal. 2010; Franke 2015b). These deposits of the Car-

boniferous “Kulm” facies are characterized by a variable dipping of 0–90° and are strongly

fissured due to the Variscan orogeny (the Visean of the E Ob 1/68 borehole, Fig.1). Dur-

ing Permo-Carboniferous times, Brandenburg was part of a back-arc extension regime

of the Variscan foreland. In the Westphalian, there was in contrast to the coal-bearing

deposits of large areas of Northwest Europe, non-sedimentation in the study area (Kom-

brink etal. 2010). Due to the progressing thermal subsidence of the evolving exten-

sional regime, the Permian Basin System developed. As a first consequence, an intense

volcanic activity resulted in thick successions of Permo-Carboniferous volcanic rocks

(Fig.1). These volcanic sequences do often represent a kind of magmatic basement fill-

ing of the sedimentary NGB. According to Breitkreuz and Geißler (2015), Mg-andesitic

rocks dominate in the East Brandenburg Sub Province (Geißler etal. 2008). About 48

boreholes encountered the volcanic succession, but only 10 drilled the volcanic com-

plex completely in East Brandenburg. As described by Benek etal. (1996) and Geißler

etal. (2008), the Permo-Carboniferous volcanic succession is characterized by different

mineralogical composition and variable rock texture according to the magma, eruptional

type and stage, whereby two of five eruptional stages are present in East Brandenburg.

The oldest volcanic rock units of the first eruption stage consist of dacitic rocks, fol-

lowed by lower basaltic andesitic rocks, rhyolitic rocks and middle and upper basaltic

andesitic rock units. In East Brandenburg the volcanic succession ends with trachytic

rocks of the early phase of the second eruption stage in the lowermost Asselian (Benek

etal. 1996). The andesitic rocks do predominate the entire succession and built up to

80% of the total volcanic rock (Huebscher 1995). The andesites are commonly porphy-

ritic consisting of plagioclase, orthopyroxene and olivine (Benek etal. 1996). According

to Benek etal. (1996) the entire andesite complex averages a thickness of 200–500m

with a local maximum thickness of more than 1000m at shield volcanos (E Ob 1/68 well,

Fig.1). Based on their analysis, an initial thickness of about 200m could be expected for

the Groß Schönebeck area.

Middle European Permian (Dyas)

Sedimentary Rotliegend

During the Permian, the subsidence of the NGB causes the deposition of large volumes

of sedimentary rocks. In Brandenburg, the primary source rocks of these Rotliegend

sediments were the thick andesitic rock sequences. Carboniferous rocks were, although

often separated by an unconformity from the Rotliegend sediments, not source rocks

of the deposits (Rieke 2001). The high altitude areas of the volcanoes were eroded and

deposited in braided plain and aeolian to fluvial environments at the basin margin and in

sand flat and mud flat environments at the distal areas of the basin centre. Different sub-

sequent climatic and tectonic events trigger basin-wide traceable sedimentary cycles in

the Rotliegend with sequences of thicknesses of 20–100m (Rieke etal. 2003). The cycles

Page 6 of 44

Nordenetal. Geothermal Energy (2023) 11:1

often start with clay/mud-dominated horizons (highstand) and evolve to more regres-

sive sediments (shoreface and deltaic sands toward the top which progrades laterally into

offshore shales, lowstand) and end with the next maximum flooding surface (highstand;

Gast 1995). According to Gebhardt etal. (1991), tectonic events are the main cause for

the development of the fining-upward cycles of the Parchim, Mirow, Dethlingen und

Hannover Formations. The climatic conditions during the Rotliegend were semi-arid to

arid, causing the dominating Fe-oxidized reddish colour of the deposits.

The area of Groß Schönebeck is situated in a SE marginal position of the NGB. Here,

clast supported coarse-grained conglomerates and sandstones of the Havel Subgroup

cover the Permo-Carboniferous volcanic rocks (E GrSk 3/90 borehole, Figs.1 and 2).

Holl etal. (2005) interpreted these deposits as fluvial sediments of coarse-grained bed-

load rivers in a braided plain environment. In the E GrSk 3/90 borehole, the multisto-

ried channels were deposited in a NNE to NW striking depositional system with a mean

paleaocurrent direction of 24° for the Lower Havel Subgroup and 340° (NW) for the

Upper Havel Subgroup (Holl etal. 2005). By the end of the Havel Formation, the land-

form configuration changed fundamental. Due to thermal subsidence, the North-Ger-

man trough extended further to the west reaching the Netherlands and England (Gast

and Gebhardt 1995). The rise of the hinterland allows the development of erosive sandy

deposits, which cover the entire southern margin of the NGB. These quartz-dominated

sandy deposits represent one of the geothermal reservoir target, the Elbe reservoir sand-

stone (ERS) that is equivalent to the so-called Elbebasissandstein (EBS) of Bauer etal.

2020.

The ERS is well documented in boreholes along the marginal areas of the NGB (Fig.2

and Gast etal. 1998; McCann 1998). Stratigraphically, the ERS comprises parts of the

Fig. 2 Rotliegend in East Brandenburg (Groß Schönebeck) as encountered in selected boreholes (interpreted

from drilling reports) and respective facies interpretation according to Doornenbal and Stevenson (2010;

inset map). ERS marks the sedimentary geothermal target (Elbe reservoir sandstone). GR are gamma-ray log

readings for correlation (partly digitized)

Page 7 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Dethlingen Formation, the Hannover Formation, and possible parts of the Mirow For-

mation (Fig.2). The ERS shows a variable thickness of up to about 200m near the coast-

line (Lindert etal. 1990) and thins out toward the basin centre. Many samples of the

ERS show a bimodal grain-size distribution. Plein (1995) interprets the sandstone to

represent sand that was accumulated under aeolian conditions of the hinterland first

before it was transported by aquatic processes toward the basin and lithified. In the E

GrSk 3/90 well, the ERS shows a thickness of about 40m within the Dethlingen Forma-

tion (Bauer etal. 2020, sandstone interval with low GR intensity in Fig.2). According to

Holl etal. (2005), the fine-to-coarse-grained sandstones were deposited in an ephemeral

stream floodplain environment. The palaeocurrent direction distribution is more vari-

able than in the Havel Subgroup but is still to the NW (mean azimuth: 290°; Holl etal.

2005). In open-hole logs, the ERS is characterized by low gamma-ray values and shows a

high quartz content. In addition, decreased P-wave velocities observed by sonic logging

indicate an increase of porosity (Trautwein and Huenges 2005). These two observations

explain the general interest in the ERS as a geothermal target, hosting water of about

150°C temperature in Groß Schönebeck (Huenges 2002).

Within Rotliegend times, the sedimentation regime in the central area of the basin got

more and more influenced by cyclic fluctuations of the water table, and a growing salt

lake developed from the central part of the basin (Gast and Gebhardt 1995). A progres-

sive planation of the morphology in combination with the reduction of sediment supply

resulted in the development of sediments of the mud flat facies. The playa deposits cover

large parts of the NGB during the late Rotliegend (Rieke etal. 2001; Gast etal. 2010).

This is also the case in Groß Schönebeck, where mudstones do predominate the lithol-

ogy of the Hannover Formation, partly interrupted by sandy deposits of a sandy mudflat

environment.

Zechstein

During the Late Permian, the basin developed into an intracontinental topographic

depression which was rapidly flooded by a catastrophic transgression from the Barents

Sea (Peryt etal. 2010; Strozyk etal. 2017). In many areas, the uppermost 10–15m of

Rotliegend sandy sediments were reworked and form the Weissliegend which locally

grades into limestone and is overlain by the Kupferschiefer (Peryt etal. 2010). Subse-

quently, cyclic occurring flooding events lead to the deposition of 1500–2000m of Zech-

stein deposits reflecting progressive evaporation (e.g., Zhang etal. 2013). The cyclicity

is represented by the Zechstein deposits consisting of transgressional carbonates and

mudstones followed by evaporates (Peryt etal. 2010). The nowadays thickness of Zech-

stein deposits is very variable and triggered by post-Permian salt movement (salt tecton-

ics) and erosion (see later in text). In Groß Schönebeck, which is located on top of a salt

pillow, the Zechstein sequence shows a total thickness of approximately 1500m.

Post‑Permian deposition andevolution ofsalt structures

In the late Permian, a phase of accelerated subsidence commenced because of thermal

contraction and continued until the end of the early Triassic in the NGB. Since then,

subsidence rates were decreasing exponentially according to a thermal subsidence pat-

tern (Scheck and Bayer 1999). Only for time intervals in the late Triassic as well as the

Page 8 of 44

Nordenetal. Geothermal Energy (2023) 11:1

late Cretaceous and Cenozoic, the subsidence rates were accelerated again, varying spa-

tially in magnitude within the basin (Scheck and Bayer 1999; Kossow and Krawczyk

2002). In the mid-to-late Triassic, the thinning of supra-salt sediments due to an exten-

sional regime in conjunction with subsidence caused instabilities of the Zechstein salt

deposits and initiated the formation of salt structures (Kossow etal. 2000; Scheck-Wen-

deroth etal. 2008). In the late Cretaceous to earliest Cenozoic, salt diapirism was associ-

ated with compression (Scheck etal. 2003). After this compressive phase, the Cenozoic

subsidence phase enabled further intensive salt movement. In relevant areas, Pleistocene

glaciations may have triggered still active salt movements due to the loading and unload-

ing of ice sheets (Strozyk etal. 2017).

German Triassic (Buntsandstein, Muschelkalk, Keuper)

The deposits of the Buntsandstein form the first sediments above the Zechstein. Still

arid conditions with fluviatile sedimentation did prevail during that time (Stack-

ebrandt and Röhling 2015). Only the Middle Buntsandstein shows higher depositional

energies resulting in a higher and coarser-grained sand content, while the Lower and

Upper Buntsandstein consists of fine-grained (clayey) sediments. The coarser-grained

sandy deposits within the Volpriehausen, Dethfurt, Hardegsen, and Solling Formations

(Middle Buntsandstein) are often discussed as possible geothermal reservoirs. At Groß

Schönebeck, the thickest sandstone interval occurs in the Dethfurt Formation with a

thickness of 10m, showing a cleaner sand interval of about 6m and temperatures of

85°C at a depth of 1870m. The ingression of marine conditions in the Upper Buntsand-

stein and the forming of evaporates resulted in basin-wide traceable impedance con-

trasts in the lithological succession and in prominent seismic markers (S1 and S2, Fig.3).

In the Muschelkalk, the NGB was connected in the south with the Tethys Ocean and

formed an epicontinental flat sea. Calcareous sediments such as marlstones and lime-

stones do represent the predominant lithotypes of this time. The Muschelkalk is divided

in three subunits (Lower, Middle, and Upper). In the Lower Muschelkalk, oolithic lime-

stones of the so-called Wellenkalk could represent a potential geothermal reservoir if

fractured and appropriate fluid paths are present. In Groß Schönebeck, the E GrSk 3/90

borehole did not observe any fluid flow in this succession during drilling. Temperatures

of 70°C are measured in the respective depth interval (1500–1550m). In the Middle

Muschelkalk, the connection to the Tethys was sporadically closed, resulting in the for-

mation of evaporitic sediments. Basin-wide traceable seismic marker horizons are con-

nected to this event (M1 and M2, Fig.3).

The Keuper represents the Upper German Triassic. Keuper sediments are predomi-

nantly characterized by fine-grained deposits of the stillwater facies, of fluviatile facies,

and subordinate of marine facies. Based on basin-wide recognizable discontinuities,

the Keuper is subdivided in several formations (Fig.3, e.g., Beutler and Franz 2015).

Depending on the respective lithological composition and succession, the disconti-

nuities are partly related to more or less pronounced seismic reflectors (K1, K2, Fig.3).

According to Beutler and Franz (2015), the unconformity at the boundary of the Grab-

feld Formation and the Stuttgart Formation was related to tectonic events which also

causes the first salt diapir forming phase. The salt structure of Groß Schönebeck formed

Page 9 of 44

Nordenetal. Geothermal Energy (2023) 11:1

during Keuper times and represents a salt pillow with only minor hiati of less than 30m

(Beutler and Franz 2015).

Jurassic, Cretaceous andCenozoic

The movement of salt during the Upper Triassic causes the formation of troughs

and highs and affects post-Triassic sedimentation and erosion processes. For Groß

Schönebeck, only Lower Jurassic (Northern Lias Group) sediments are present in the

drillings on the salt pillow (Fig.4). The deposits represent marine shale facies and are

partly interfingering with shallow-marine sands and limnic and terrestrial sediments.

The change of lithological composition due to different facies conditions allow the map-

ping of several seismic horizons with variable reflectivity (L2 and L4, Fig.4).

During most of Lower Cretaceous times, almost the complete area of East Branden-

burg was part of a structural high without any preserved sediments. Finally, the highland

of East Brandenburg became part of a marine depositional environment, which contin-

ued to the Upper Cretaceous. Depending on the particular structural situation (paleoge-

ography), respective sediments were deposited (e.g., E GrSk 2/76, Fig.4).

In the Tertiary, large parts of the NGB became flooded. Marine clayey sediments of

the Oligocene (the Rupelian “Rupelton”) document the basin-wide marine transgression

of the paleo-North Sea. In salt rim synclines, the Tertiary could achieve a much greater

thickness (see E Gür 3/76, Fig.4). Changing water tables and coastline conditions in the

Miocene allow the formation of coal beds (lignite) in southeast Brandenburg. In the late

Fig. 3 German Triassic deposits (thickness, lithological composition, and prevailing rock colour) as

encountered in boreholes in East Brandenburg, interpreted from unpublished drilling reports. For location of

boreholes, see Fig. 1. GR are gamma-ray log readings for correlation (partly digitized)

Page 10 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Tertiary (Middle Miocene to Pliocene), the marine conditions in Brandenburg vanished

owing to another regression. Therefore, sediments of that age are almost not present in

northeast Brandenburg.

The Quaternary deposits are dominated by glacial sediments of the different ice ages

(boulder, sand, clay, till, Fig.4). They host the main fresh water resources. Due to glacial

troughs that cut into the underlying strata and allow the deposition of glacial sediments,

the Quaternary thickness could vary significantly on short distances.

Data andmethods

The presented study integrates various types of subsurface data, covering different scales

and different qualities that are shortly addressed in the following (Table1). The data were

evaluated and used to establish a new geological model of the site and to allow a more

realistic parameterization of the Permo-Carboniferous reservoir target. Petrophysical

Fig. 4 Jurassic, Cretaceous and Cenozoic deposits (thickness, main lithological composition and prevailing

rock colour) as encountered in the Grüneberg (E Gür 3/76) and Groß Schönebeck (E GrSk 2/76, E GrSk

3/90) boreholes in East Brandenburg (interpreted from unpublished drilling reports; GR are gamma-ray log

readings for correlation, partly digitized)

Page 11 of 44

Nordenetal. Geothermal Energy (2023) 11:1

properties to be considered in the facies-depending modelling are total and effective

porosity, density, permeability and thermal properties (thermal conductivity, thermal

diffusivity, heat capacity).

Literature andmap data

For regional correlation, the geological atlas of Brandenburg (Stackebrandt and Man-

henke 2010), providing different thickness and depth maps of units of the Mesozoic and

Cenozoic was used. In parts, former synopsis representations of legacy exploration data

for facies and structural interpretation could be used (e.g., Lange etal. 1981; Doornenbal

and Stevenson 2010).

Borehole data andevaluation ofpetrophysical properties

Mainly due to the efforts of the hydrocarbon exploration in the time period of 1960–

1990, several deep drillings provide valuable underground information and are avail-

able for cross-correlation (Hoth etal. 1993). In the Groß Schönebeck area, the E GrSk

2/68 borehole, the E GrSk 3/90 borehole, which was deepened about 50m without cor-

ing in 2001 as a geothermal well, and the Gt GrSk 4/05 geothermal well provide unique

access to underground data (Fig.1, Tables1 and 2). Of special interest are the geo-

physical logging data, still available cores (E GrSk 3/90), the respective drilling reports,

and petrophysical measurements for correlation and petrophysical interpretation and

parameterization of the model (Table2). To extend the data basis, available cores were

studied in the repository and additional samples weretaken for thedetermination of

thermal properties. The core and log data used in this study is provided by a data publi-

cation to this manuscript.

Table 2 Data and material of the E GrSk 3/90 and Gt GrSk 4/05 boreholes

The data used in this paper are available in a data publication to this manuscript (Norden etal. 2022)

a) Core data (E GrSk 3/90 only; coring in Gt GrSk 4/05 was planned but could not be realized). The E GrSk 3/90

borehole was cored in the depth range of ca. 4040–4270 m (230 m). Due to disposal of core material in the late

1990s, only the lowermost 63 m of this section are still available in the repository

Density and porosity In total 344 measured samples: 287 legacy samples (Hamann et al.

1991), 29 samples (Trautwein 2005), 17 samples (Lotz 2004), 11 samples

(this study)

Gas permeability In total 137 measured samples: 109 legacy samples (Hamann et al.

1991), 28 samples (Trautwein 2005) plus 3 measured under in-situ

conditions (Trautwein 2005)

Thermal conductivity Lotz (2004); Norden et al. (2022)

Thermal diffusivity Norden et al. (2022)

b) Well logging

Stratigraphy E GrSk 3/90 Gt GrSk 4/05

Post-Rotliegend Gamma-ray (GR) GR

Prae-Zechstein GR

Temperature log

Sonic/velocity log

Bulk density log

Neutron porosity log

Pulsed neutron log

Electrical image log

GR, Spectral GR

logging tools used for correlation

only due to inconsistent quality

(mineral detection, dual laterolog,

monopole acoustic)

Page 12 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Geophysical logging data

By working with the well-logging data it soon became obvious, that the data of the E

GrSk 3/90 borehole and especially of the Gt GrSk 4/05 borehole needed a depth correc-

tion based on a consistent depth reference log covering the complete drilled sequence.

Therefore, a master gamma-ray log was chosen from the E GrSk 3/90 and used for depth

calibration. This enabled a consistent interpretation of the drilled lithological and strati-

graphical units for the two close-by boreholes. In the E GrSk 3/90, beside an undisturbed

temperature log, an acoustic, a density, a neutron, and an electrical image log was meas-

ured in the Rotliegend reservoir section (Table2). The latter was used for an analysis of

depositional structures (Holl etal. 2005). Based on the work of Holl etal. (2005), an anal-

ysis of the sedimentary dip azimuths using the azimuth-vector plot method (after Rider

2000) was applied in the current study. For this method, dip azimuth values are plotted

sequentially in their true orientation but without any depth scale. Dip azimuth changes

due to different sedimentary regimes will result in different line orientation.

Permeability could be deduced from a pulsed neutron log that was measured over

parts of the sedimentary reservoir section. Permeability was additionally estimated for

the sedimentary Rotliegend based on the approach of Coates etal. (1991) according to

where k is permeability,



is total porosity, B is bound fluid volume (calculated as the

product of the volume of clay, VCl, and the clay total porosity,

Cl

), F represents the free

fluid volume (F =



− B), and a, b, c are empirically derived constants. The Coates equa-

tion is fitted to laboratory permeability data, corrected for in-situ conditions, by manu-

ally adjusting the constants a, b, and c (see later in text).

For a first evaluation of permeability of the volcanic rock sequence, we used a correla-

tion based on core investigations given by Siratovich etal. (2014) for andesitic rocks of

the Taupo Volcanic Zone in New Zealand. They establish a relation between connected

porosity (PHI) and permeability (PERM) for the Rotokawa andesite that we applied to

our data. The porosity needed in the calculation was estimated from the respective sonic

log (Table2) using the Wyllie time-average equation (Wyllie etal. 1956).

The thermal conductivity (TC) for the igneous rock section was determined using the

empirical approach of García etal. (1989) developed for andesitic rocks of the Los Azu-

fres geothermal field in Mexico. They used TC measurements under ambient conditions

on low-porosity dry core samples, showing similar values as on andesitic samples of the

Northeast German Basin, and correlate them with porosity and bulk density (BD) data

according to the following formula:

To apply their approach on the log data of E GrSk 3/90, we rely on the above calculated

porosity from the sonic log and use the sonic also for the density estimation. Instead of

(1)

=a·b



c

(2)

log







=3.7221159 −0.00472402 ∗PHI[%]−0.000594151 ∗PHI[%]2



−log







Page 13 of 44

Nordenetal. Geothermal Energy (2023) 11:1

using the Gardner’s relation (Gardner etal. 1974), which is commonly applied for sedi-

mentary rocks, we used the provided measured properties of Siratovich etal. (2014) to

establish a specific correlation of sonic velocities and BD for andesitic rocks:

Specific heat capacities (SHC) of the volcanic rock section were calculated using a for-

mula provided by Heap etal. (2020), developed for andesitic rocks of Mt. Ruapehu in

New Zealand based on porosity, bulk and matrix density:

Because both approaches (for TC and SHC estimates) provide ambient values, not

considering in-situ pT conditions, corresponding corrections were applied. The TC cor-

rection was calculated as a summary effect of single corrections on TC for the respective

p and T conditions (TCp and TCT, respectively).

The p effect on TC of magmatic rocks (TCpm) was considered based on the equation

of Fuchs and Förster (2014) and the T effect on TC (TCTm) was corrected following the

(3)

BD

3·103



=0.0278 ·Sonic



s

0.5404,R=

0.63.

(4)

SHC

J

kgK=

2750





·750



kgK



·(1−PHI[dec])+1000





·4182



kgK



·PHI[dec

]





Table 3 Seismic horizons mapped in the new Groß-Schönebeck 3D seismic data set, calibrated with

borehole data

Reflector names are according to Reinhardt (1993)

Reflector Horizon Reflector quality Stratigraphy

B2 Near base of Upper Cretaceous Weak (uncertain) CRETACEOUS

BLC Near base of Lower Cretaceous Weak

L2 Within Jurassic (Pliensbachian) Variable JURASSIC

Lias

L4 Near base of Lower Jurassic Strong

K2 Near top of Weser Formation Variable (uncertain) TRIASSIC

Keuper

K3 Near top of Grabfeld Formation Well developed

M1 Near top of Middle Muschelkalk Strong TRIASSIC

Muschelkalk

M2 Within Middle Muschelkalk (anhydrite) Well developed

M3 Near base of Mittlerer Muschelkalk Strong

S1 Within Röt Formation (top of anhydrite) Strong TRIASSIC

Buntsandstein

S2 Near base of Röt Formation Strong

X1 Near top of Zechstein Strong PERMIAN

Zechstein

X3 Near basal anhydrite (Leine Formation) Strong

Z1 Near top of basal anhydrite (Staßfurt Fm.) Very strong

Z3 Near base of Zechstein Well developed

R3 Within Dethlingen Formation Variable (uncertain) PERMIAN

Rotliegend

Top ERS Near top of Elbe reservoir sandstone Variable (uncertain)

Base ERS Near base of Elbe reservoir sandstone Well developed

R6 Near base of sedimentary Rotliegend Well developed

R8 Near base of volcanic succession Very weak (uncertain) PERMOCARBONIF-

EROUS

Page 14 of 44

Nordenetal. Geothermal Energy (2023) 11:1

approach of Sekiguchi (1984), adapted for T in °C, TC in Wm−1 K−1, and ambient T of

20°C (293.15K) instead of 15°C (288.15K).

Waples and Waples (2004) provide a comprehensive review on SHC of rocks, min-

erals, and subsurface fluids. They conclude that p corrections on SHC of solids can be

neglected. Therefore, SHC was corrected for T following the procedure given by Waples

and Waples (2004).

The in-situ thermal diffusivity (TDin-situ) finally was calculated based on the corrected

thermal conductivity and heat capacity values and the estimated bulk density according

See data publication for details on the calculations.

Core data

The petrophysical data compilation includes density, porosity, permeability, thermal

conductivity, and thermal diffusivity of different core samples from the E GrSk 3/90

borehole, measured by different authors (Table2, also in data publication).

For petrophysical interpretation, the legacy gas-derived laboratory permeabilities

of the Rotliegend were corrected taking pressure and brine effects into account using

the approach of Juhasz (1986). Juhasz provides correction formulas to correct for three

important factors contributing to the discrepancy between routine gas-permeabil-

ity data and in-situ intrinsic brine permeabilities: (a) gas slippage (Klinkenberg effect;

Klinkenberg 1941), (b) absence of confining stress on the sample, and (c) the dry meas-

urement condition of gas permeability measurements (possibly effecting the pore

structure). Depending on the value of the measured gas permeability, Juhasz provides

different correction formulas that were applied on the laboratory data (the details of the

correction procedure are listed in the data publication to this paper).

To enable a better thermophysical characterization of the Rotliegend, additional cores

were taken from the core repository, measured, and evaluated for thermal conductiv-

ity, thermal diffusivity, and specific heat capacity. The under ambient laboratory-derived

parameters were corrected for in-situ pressure and temperature conditions, taking cor-

rection functions for sedimentary and magmatic rock types into account (Fuchs and

Förster 2014; Somerton 1992; Sekiguchi 1984; Emirov etal. 2017). The data and the

applied methodology is presented in the accompanying data publication.

Seismic data

The main input for the structural geological model is the acquired 3D seismic of Groß

Schönebeck (Table2). Main acquisition and processing parameters of this survey are

reported in Krawczyk etal. (2019). They provided also a first geological interpreta-

tion of the data, but without a detailed analysis and without establishing a geologi-

cal model. The latter is the focus of the manuscript at hand. For well-tie integration,

data from a vertical seismic profile conducted in the E GrSk 3/90 and Gt GrSk 4/05

(5)

in-situm2

s=

TCin-situ









·SHCT



kgK



Page 15 of 44

Nordenetal. Geothermal Energy (2023) 11:1

boreholes with a distributed acoustic sensing system (Henninges etal. 2021) provided

important input. The study of Bauer etal. (2020) providing a seismic facies classifica-

tion on the Rotliegend sandstone reservoir was used to enhance the structural model-

ling and petrophysical property simulation (e.g., thickness and porosity distribution)

for the ERS. The current interpretation of possible reservoir thicknesses of Martu-

ganova etal. (2022) was considered as well. In addition, former legacy 2D seismic

surveys in the study area of the 3D seismic were available in a digital format or as

georeferenced scanned images for comparison.

Hydraulic data

Thereservoir targets, the Permian Rotliegend ERS and the drilledsuccession of the vol-

canic rocks were stimulated hydraulically in Groß Schönebeck. Blöcher etal. (2016)

describe the details on the stimulation history and respective data (see also references

therein). The stimulations provide information on the in-situ hydraulic and mechani-

cal behaviour and the stress regime of the Permian reservoir zones. During stimulation,

passive seismic sensing was applied. The recorded microseismic events (Kwiatek etal.

2010) and their in-depth interpretation (Blöcher etal. 2018) provide further informa-

tion on the reservoir setting and model parameterization showing that at least two of the

so far interpreted fault planes would show slip tendencies above a friction coefficient of

0.85. However, there were no seismic events recorded for these planes, implying that the

existence of these faults (derived from 2D seismic interpretation) should be questioned

(Blöcher etal. 2018).

The available types of underground data were interpreted using the commercial inter-

pretation software Petrel 2016, which was also partly used for seismic analysis, seismic-

well tie, horizon interpretation, model building, facies simulation, and petrophysical

modelling. Also seismic attribute analysis and visualization techniques were performed

in time and depth-domain volumes using the Petrel 2016 software package.

Seismic‑well tie andhorizon mapping

Seismic-well ties rely on the available logging data and horizon interpretations. For the

GroßSchönebeck data, in a first step, composite gamma density and sonic velocity logs

were compiled for the depth range of the E GrSk 3/90 borehole (Fig.5). Because sonic

velocity and gamma density were not measured above 2332m and 3850m, respectively,

this composite log contains logging data from neighbouring wells covering the same

stratigraphy and similar lithology and, additionally, for uncovered sections estimated

density values. The resulting composite logs should represent at least a realistic sonic/

density-distribution scenario for the entire drilled sequence. Additional velocity data

were acquired with the DAS technique and provide a direct and robust time-depth rela-

tion that was used to calibrate the compositional sonic log. These data are available from

a depth of 815m to about 4250m, covering one-way travel time and respective (meas-

ured and true vertical) depth information with a spacing of 25m. Based on the calibrated

sonic data, a synthetic seismogram was modelled to support the horizon interpreta-

tion of the 3D seismic PoSTM data. The depth-converted PreSDM-DeMultiple volume

was processed to remove reflection horizon multiples especially for the sub-salt depth

Page 16 of 44

Nordenetal. Geothermal Energy (2023) 11:1

domain. For this purpose, a data-driven approach (e.g., Jakubowicz 1998) was applied

to predict and substract undesired interbed multiples before pre-stack depth migration.

Horizons interpreted in that volume were later shifted to the respective horizon depth

encountered in the boreholes.

Fig. 5 Seismic-well tie of borehole data (E GrSk 3/90 borehole) and seismic volumes. Vp* refers to p-wave

velocity (in kms−1), RHOB to bulk density logging (in 103 kgm−3 or gcm−3), and RC represents the reflector

coefficient, ERS: Elbe reservoir sandstone. The synthetic seismic response based on the applied wavelet

is shown together with two processed seismic volumes: PoSTM (post-stack time migration) and PreSDM

(pre-stack depth migration with suppression of seismic multiples). Stippled lines of the sonic-density

composite plot (Vp*, RHOB*) indicate interpolated log responses, see text

Page 17 of 44

Nordenetal. Geothermal Energy (2023) 11:1

The complete suite of seismic horizons and their interpretation in the seismic vol-

ume is given in Table3. The uppermost seismic reflector, which is traceable in the

seismic volume, represents the L2 reflector. Reflectors above are fragmentary and

hard to follow in the seismic volume. Dominant, continuously developed reflectors

are the L2, L4, M2, S1, S2, X1, X2 (X3), and the Z(1–3) reflectors (c.f., Krawczyk etal.

2019). Less pronounced are the reflectors K2, K3, M1, M3, R2, and R6(H6). A distinct

reflectivity related to the base of the volcanic rocks (R8/C1) was not observed in the

volume.

Structural andlithological interpretation

The focus of the 3D seismic survey aimed at the exploration of the Rotliegend (pre-

Zechstein; Krawczyk etal. 2019), so that the seismic survey was optimized for imag-

ing deep targets which results in a lower coverage of the shallower subsurface. The

most dominant seismic feature within the data is the Zechstein salt structure. While

the sedimentary Rotliegend and the top of the Permo-Carboniferous volcanic rocks

were also imaged by the seismic data, deeper Pre-Permian structures are hard to

elaborate, the more since related borehole data are absent. Figure6 shows for one

section of the seismic volume the challenges associated with the geological interpre-

tation at salt structures. The seismic processing applied and its visualization affects

the overall appearance of reflector continuity and intensity. To improve the correct

location of reflection surfaces, the CRS (common reflection surface)-stack-based

seismic reflection imaging is providing information that is more reliable (Fig.6A vs.

B, C). Compared with conventional seismic reflection processing, the CRS method

(e.g., Mann etal. 1999) provides stacking results with higher signal-to-noise ratio by

involvement of more traces from neighbouring CMP (common-midpoint) locations.

Moreover, unlike in conventional stacking, the CRS method is based on a purely data-

driven design of the stacking operator, which allows an improved imaging of complex

Fig. 6 Depth-converted seismic sections along NW–SE trending profile B (for location see Fig. 7). A Post-stack

time migration without CRS stack, B pre-stack depth migration with CRS stack, C pre-stack depth migration

with multiple reduction (see also Table 1). Black arrows indicate processing artefacts; the red arrow marks a

multiple reflection

Page 18 of 44

Nordenetal. Geothermal Energy (2023) 11:1

geological structures. Due to strong velocity contrasts and changes by the salt dom-

ing, the corrections are highly relevant. Reflection multiples of shallower surfaces

may also overlay deeper (and weaker) reflections. Processing of the seismic volume

by calculation of the behaviour of reflector multiple of main shallow reflectors and

subtracting them from the deeper parts of the volume may allow a more precise inter-

pretation (Fig.6C). However, the complexity of the processing procedure may also

introduce (artificial) artefacts like at the edges of the volume and for the trace-like

feature visible in Fig.6B, C.

Pre‑Permian andPermo‑Carboniferous volcanic rocks

Some local structures and internal features within the pre-Permian are present but hard

to relate to a more specific geological interpretation (Fig.7). The volcanic rocks encoun-

tered in the E GrSk 3/90 and Gt GrSk 4/05 boreholes are not well characterized by the

seismic volume. Changes in thickness of the volcanic succession or in its chemical com-

position is not resolved by the seismic data. In profile B and C (Fig.7), there is an area

of increased reflectivity visible in a zone about 1km east of the GrSk drill site. Remark-

ably, the profile B shows in that zone a dominant feature with changing polarities (black

arrow), probably related to a heterogeneous lithology, a fractured or tilted structures

of the Carboniferous or even to processing artefacts rather than reflecting gas-bear-

ing units. Based on the seismic data, at least two scenarios for the base of the volcanic

sequence (the top of Carboniferous) are possible. At the supposed top of Carboniferous

Fig. 7 Seismic cross sections imaging the Rotliegend and pre-Permian at the Groß-Schönebeck site. A

Locations of the profiles presented and borehole E GrSk 3/90. B, C NW–SE sections, D NNE–SSW section.

The base of the Zechstein salt is evident by the dominant reflector band in all three sections (the lowermost

interpreted as Z3). Mainly homogeneous internal reflections within the Rotliegend successions are prevailing

(R3, R6, C1), and the Elbe reservoir sandstone (ERS) could be recognized as continuous reflection band.

Several internal features occur in the pre-Rotliegend below the base of the Havel Subgroup (R6, black arrows).

The red arrows mark seismic multiples

Page 19 of 44

Nordenetal. Geothermal Energy (2023) 11:1

in the E GrSk 3/90 borehole, a weak seismic reflector is more or less traceable in the

seismic volume (the upper C1? indication in Fig.7). However, the lithostratigraphical

boundary was indirectly deduced by well-log interpretation, only (Holl etal. 2005), and

the interpretation is still under debate. There is a second reflectivity in a depth range of

about 4400m that is often recognizable in the seismic volume. The reflector is beyond

well control but could represent an internal reflector within the Carboniferous, or even

correspond to a reflectivity related to the top Carboniferous. We mapped both: one

referring to a volcanic sequence thickness of about 70m (Fig.8A) and another referring

to the lower C1 reflector shown in Fig.7, referring to a thickness of more than 200m

(Fig.8B).

Permian

While the petrothermal target of the Permo-Carboniferous volcanic rock succession is

not very well resolved by the seismic data, the base of the sedimentary Rotliegend, corre-

sponding to the base of the Havel Subgroup for the area of the seismic survey, is related

to a seismic reflector in a depth of about 4140m that is named R6. The R6 reflector

(Table2 and Fig.7) marks the transition of well-cemented conglomeratic deposits of the

Havel Subgroups to the volcanic extrusive rocks and is related often to a zero crossing

from negative to positive amplitude change (from lower to higher velocities).

Above the R6 reflector, the ERS represents a well traceable unit with lower seismic

velocities, represented by lower amplitudes at the transition from the more porous sand-

stone to the conglomeratic but more dense Havel Subgroup in Fig.7. Due to the low

thickness of the ERS, the true thickness distribution could not be resolved from the seis-

mic data directly. Therefore, we used the analysis of Bauer etal. (2020) to constrain its

Fig. 8 Thickness maps determined from the 3D seismic data in Groß-Schönebeck (contour lines are given in

meters; see text for detail). Two alternative interpretations of the Permo-Carboniferous volcanic succession

are given, following the reflection found at the formerly hypothesized thickness of ca. 70 m (A) and the

interpretation of the here introduced C1 reflector (B). C Sedimentary Rotliegend, D Zechstein, E Post-Permian

succession. The cross marks the Groß Schönebeck drill site (E GrSk 3/90)

Page 20 of 44

Nordenetal. Geothermal Energy (2023) 11:1

thickness better. In their approach, signal attributes are calculated along the ERS hori-

zon using the continuous Morlet wavelet transform, based on a short mother wavelet to

allow for the temporal resolution of the relatively short reflection signals to be analysed.

The derived signal attributes were classified with a machine learning method. Subse-

quent modelling of the classification results provided estimates of layer thickness vari-

ations. Based on the seismic-well tie (Fig.5), we picked the expected top and base of the

ERS from the seismic data. Due to the thickness range, which is close to the seismic res-

olution for the corresponding depth, the mapped reflectors will not give a precise posi-

tion of the depth interval of this lithological unit except for the wellsite locations, where

we have direct information. Especially in the NW part of the volume, the top of ERS is

hard to follow. To implement the results of the seismic facies analysis (Bauer etal. 2020)

in the geological interpretation, we construct a theoretical medium positioning of the

ERS (using the average depth of the mapped seismic reflectors of top ERS and base ERS)

first. Then, trend maps of the thickness distribution from Bauer etal. (2020) together

with the picked horizons and the borehole data were used to model a more representa-

tive thickness distribution of the ERS within the seismic volume.

Another reflector in the sedimentary Rotliegend is picked as R3 reflector. It is inter-

preted as the top of the more sandy deposits of the Dethlingen Formation and may cor-

relate to near of the base of Eldena (Fig.2). The silty to clayey deposits of the Hannover

Formation and uppermost Dethlingen Formation above the R3 show often horizontal

and less pronounced reflectors (Fig.7).

Faults within the sedimentary Rotliegend are not traceable along several seismic lines.

There are some indications for possibly subseismic faults in certain lines but they vanish

on a very small scale, i.e., between two lines (< 30m). Attribute analyses for the base of

ERS and other horizons (like R3 or R6) do not show any distinct fault pattern.

The sedimentary Rotliegend shows a smooth trend of lower depths in the northeast

(about 4095m) compared to the southwest (around 4185m). The total thickness from

the base of the Havel Subgroup (R6) to the base of the Zechstein succession (Z3) is

increasing from NE to SW from about 300 to close to 400m in the southern margin of

the seismic volume with a mean thickness of 345m (Fig.8B).

The Zechstein deposits represent a succession of rocks with different density and

sonic velocity, for instance of salt and anhydrite or salt and limestone. The resulting

strong impedance contrasts are providing strong and distinct seismic reflectors in

this formation. Due to the basin-wide cyclicity of the Zechstein deposits, these seis-

mic markers are also traceable basin-wide on seismic sections. The base of Zechstein

(Z3, Figs.5, 6, 7) is seismically very well developed, because the anhydrite–mudstone

transition from Zechstein to the Upper Rotliegend has a strong acoustic impedance

contrast. It is located at a depth of ca. 3750–3800m. In the E GrSk 3/90 borehole,

the base of the Zechstein succession (the Werra Formation) consists of a 30-cm thick

black mudstone (far below seismic resolution), representing the “Kupferschiefer”, 5m

of limestones and marlstones, and 67m of anhydrite (intercalated with anhydritic

halite). Above the Werra Formation, representing the first Zechstein cycle, the basal

Staßfurt Formation (2nd Zechstein cycle) is composed of limestone (ca. 5.5m thick)

and anhydrite (ca. 2.5m thick) which is overlain by more than 1115m of halite, fol-

lowed by 100m of sylvine and ca. 1m of anhydrite. The Z1 reflector corresponds to

Page 21 of 44

Nordenetal. Geothermal Energy (2023) 11:1

the transition of the Staßfurt salt to the underlying anhydrite (Fig.5). The 3rd Zech-

stein cycle is represented by the Leine Formation. At the base, a couple of meters of

dolomitic mudstones are present, followed by 45m of anhydrite and 150m of halite

with an intercalation of 6m thick clayey anhydrite. The impedance contrasts of the

anhydrite of the Leine Formation and the rock salt of the Staßfurt formation cause

another strong reflector (X3 or the so called “Z3 stringer” for the third Zechstein

evaporation cycle (Table2). The Aller and Ohre Formations represent the youngest

two cycles of the Zechstein succession in Groß Schönebeck. Above a few meters of

clayey and anhydritic sediments, salt rocks are present: ca. 50m and 12m in the Aller

Formation and the Ohre Formation, respectively. The mapped X1 reflector corre-

sponds to the anhydrite/rock salt succession near the top of the Zechstein. Figure8C

shows the thickness distribution of the Zechstein deposits that clearly outlines the

anticlinal structure underneath Groß Schönebeck.

At the top of the anticlinal structure, a pronounced graben-like structure is pre-

sent in the X3 horizon. The main faults are located ca. 1km north of the E GrSk 3/90

borehole and is NW–SE oriented (Fig.9A, B), showing an offset of up to ca. 30m.

This feature is one to more than two kilometres in length and exhibits a complex and

circular fracture pattern at its SE margin. Because this pattern could not be mapped

seismically in the overburden it is interpreted as an internal anhydritic and compact

Fig. 9 Seismic attribute analysis applied for fault detection at the top (X3 horizon) and base (Z3 horizon) of

Zechstein. Left column: variance along interpreted horizons based on CRS volume in time (A X3, C Z3). Right

column: maximum amplitude based on CRS volume in depth (B X3, D Z3). The graben-like structure within

the Leine anhydrite (X3, A, B) is clearly visible, while fault signatures are nearly absent at the base of the

Zechstein (Z3, C, D). The cross marks the Groß Schönebeck drill site (E GrSk 3/90)

Page 22 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Zechstein stringer, overflown by rock salt that is more mobile. At the base of Zech-

stein (Z3), no basal faults are visible in the seismic volume (Fig.9C, D).

Post‑Permian

A number of reflectors show a continuous distribution pattern in the post-Permian suc-

cession. Most prominent are the S1 and S2 reflectors, the M1 and M2 reflectors, and

the L2 and B2 reflectors (Fig.5). In the seismic volume, those reflectors are very well

developed in the southern area of the survey. They are less distinct north of the GrSk

drillsite. Here, different effects are assumed to be responsible for this loss in quality of

the seismic signal: the fracture zone indicated by the broken X3 stringer at the top of the

anticlinal structure may extend toward the overburden and account for a scattering and

damping of the seismic signal. The graben-like structure, clearly visible in the uppermost

Zechstein, is not very distinct in the post-Permian succession. While the geometry of

the fault pattern in the X1 horizon shows some similarity to the faults visible in the X3

horizon, the fault offset decreases and is no longer traceable in the M3 horizon. The less

developed continuity of the seismic reflection horizons in the northern part of the study

area, clearly visible in the CRS PreSDM volume, may reflect a fault system related to

the deeper Zechstein salt pillow evolution, but not resolved in the 3D seismic data. The

local sharply limited small-scale thickness variations north of the E GrSk 3/90 borehole

shown in the compiled thickness maps (Fig.10A–C) show the impact of these possible

faults.

Fig. 10 Mesozoic and Tertiary thickness maps. A Buntsandstein (M3–X1), B Muschelkalk (M1–M3), C Keuper

(L4–M1), D Jurassic (BLC–L4), E Cretaceous (based on Stackebrandt and Manhenke (2010) and the mapped

BLC horizon), F Tertiary (mainly based on Stackebrandt and Manhenke (2010), combined with borehole data).

The cross marks the location of the E GrSk 3/90 borehole

Page 23 of 44

Nordenetal. Geothermal Energy (2023) 11:1

The general thickness distribution of the Mesozoic and Cenozoic sediments allows an

interpretation of the salt pillow evolution. The Buntsandstein thickness shows a mean

of 825m within a variability of 780–880m. Its distribution seems to be unrelated to the

later salt structure (Fig.10A). Only in the south-eastern and south-western corner of the

study area, slightly enhanced thicknesses may indicate a first initiation of the salt struc-

ture development. The thickness of the Muschelkalk (Fig.10B) shows a more general-

ized distribution pattern with larger thicknesses in the south and decreasing thicknesses

toward the top of the anticlinal structure. The Muschelkalk thickness shows thereby a

maximum variation (difference) of up to 120m in the study area. An intense evolution

of the salt structure is documented by the Upper Triassic (Keuper) sedimentary thick-

ness distribution (Fig.10C). The development of salt rim depression zones, where salt

migrates toward the anticlinal structure, allows the sedimentation of greater sediment

thicknesses, while the sedimentary thickness is reduced on top of the salt structure.

This trend continues for the Jurassic and Cretaceous sediment thicknesses (Fig.10D, E),

indicated by the slightly increasing variation of the sedimentary thickness for the both

units. The Tertiary sediment thickness is affected by the salt pillow topography and by

the Quaternary occurred glacial overprint, resulting in the erosion of Tertiary sediments

(incision trough, Fig.10F).

Reservoir model

The previously described structural model provides the framework for a new Rotliegend

reservoir model for further site development. The model comprises the Permo-Carbon-

iferous volcanic rock section and the sedimentary Rotliegend. The geological modelling

of the involved structural units and facies types represents the first step of the model

construction. In a second step, we parameterized the respective units according to the

available borehole and laboratory data.

Determination ofparameters forfacies modelling

Permo‑Carboniferous volcanic rocks

The sequence encountered in the E GrSk 3/90 borehole consists of several layered lava

beds and tuffs showing a single bed thickness of one to over three meter (based on core

and microresistivity borehole image analysis, Fig.11). Whereas the top of the volcanic

sequence is well preserved by cores showing the transition to the conglomeratic deposits

of the Havel Formation, the base of the volcanic sequence and hence it thickness is not

proven by the available data. The volcanic rocks encountered in the E GrSk 3/90 bore-

hole are of andesitic composition and show only subordinate fracturing. The rock cored

exhibits an amygdaloidal structure with variable crystal sizes. According to the observed

effusive bed thicknesses, the unit was parameterized layerwise with a vertical resolu-

tion of about 2–3m. Where volcanic bed boundaries could be observed in the borehole

image log, they were picked, indicating an N to NNW oriented mean flow direction of

the andesitic lava (330°). The thickness of a single volcanic layer amount to about 30cm

for a tuff layer to about 7m for an andesitic lava bed. Lavas do clearly dominate over

pyroclastic deposits and the mean dip of the surfaces accounts to 15° (showing a range

of 5 to 60°). Therefore, it is expected that the Groß Schönebeck site is located in a near-

medial to a near central proximal distance to the volcanic vents according to Bogie and

Page 24 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Mackenzie (1998) and that the general volcanic succession will not change fundamen-

tally within the modelled seismic volume. However, the overall thickness of the sequence

is questionable, and therefore, the composition and structuring of the sequence beyond

well control is provisional. Following the hitherto assumptions (see “Permian” section

Fig. 11 Core and log interpretation (E GrSk 3/90). Structural data from microresistivity borehole imaging

(not shown in panel), the sedimentary section is based on Holl et al. (2005). The Elbe reservoir sandstone

(SRS) is highlighted by the thick grey stippled line. CARBON.: Carboniferous; density: Lab.—laboratory

determined bulk density, RHOB—bulk density from logging, Dens_volc—density of volcanic rocks; porosity:

Lab. —porosity determined on core samples, PHIT—total porosity from well-log interpretation, Phi_volc—

porosity estimated from sonic log; permeability: Lab.(He)—routine gas permeabilities, uncorrected,

Juhasz corr.—in-situ corrected Lab.(He) perms: green dots, PNL—permeability from pulsed-neutron

logging, Coates—permeability using the Coates equation, Perm volc.—permeability of volcanic rock, red

dots—brine-permeabilities measured under in-situ conditions; thermal conductivity/thermal diffusivity:

bulk_sat—measured under ambient saturated conditions, lab in-situ—corrected for in-situ p/T conditions;

Log_multi—log-derived thermal properties of sedimentary (clastic) rocks, TC volc—ambient and in-situ

corrected thermal conductivity of volcanic rock, TD volc.—in-situ thermal diffusivity of volcanic rocks; Specific

heat capacity: Lab_sat_calc.—calculated (ambient conditions), T-corrected—temperature corrected values,

SHC volc—ambient and temperature-corrected specific heat capacity of volcanic rock

Page 25 of 44

Nordenetal. Geothermal Energy (2023) 11:1

above and, e.g., Holl etal. 2005), the sequence may show a thickness of about 70m or

more than 200m. We set up two models, one considering a thickness of 70m (model A,

shown in the following) and one considering a thickness of 200m (model B, see discus-

sion) based on the weak seismic reflector observed at a depth level of about 4.4km.

Sedimentary Rotliegend

For reservoir simulation, four different sedimentary facies types were considered

(Fig.11, Table4). Most of the coarse-grained bed-load dominated and conglomeratic

deposits of the Havel Formation are interpreted as multi-storeyed channel sediments

of a braided plain fluvial system with a paleocurrent direction toward NNE (Holl etal.

2005). To investigate the geometrical setting of this fluvial system, we determined the

mean (sm) and deviation (sd) of cross-bed thickness from the borehole image log of the E

GrSk 3/90 borehole (0.59m and 0.27m, respectively). Following Bridge and Tye (2000),

the mean dune height (hm) could be estimated with

if sm/sd equals “approximately 0.88 ± 0.3”. A generous interpretation of this criteria, (sm/sd

accounts to 0.5), will allow the calculation of hm and the mean dune depth dm according

to Allen (1970, cited in Bridge and Tye 2000) with

In our case, this may reflect a paleochannel depth of about 9m (see Bridge and Tye

2000; Leclair and Bridge 2001) and correlate to a channel belt width of about 3500m

according to empirical correlations given by Bridge and Mackey (1993), to estimate the

possible minimum (min) and maximum (max) channel-belt width (cbw):

As our study relies on data from one borehole (E GrSk 3/90) only and the used equa-

tions cover a huge spectrum of very different fluvial systems (see, e.g., Gibling 2006) and

have in general considerable large uncertainties for estimating the width, thickness and

overall geometry of fluvial channel bodies buried under the surface, the deduced geo-

metrical parameter given in Table4 may represent a rough estimation of the principal

architecture.

The second facies element represents the ephemeral stream floodplain environ-

ment identified by Holl etal. (2005) for the Dethlingen Formation. As described by

the authors, the fine- to coarse-grained sandstones are amalgamated in character

and show fining-upward trends to the top of the formation, representing proximal

to distal fluvial facies. Transport direction is toward W and NW (265–305°). Within

the lower part of the Dethlingen Formation the ERS is developed and shows small-

to-large-scale cross-bedded and low-angle cross-bedded sandstones as well as hori-

zontally laminated sands (Fig.11). The sediments are interpreted as fluvial reworked

(6)

m=2.22 ·

sm

1.8 

(7)

=11.6 ·h

0.84

(8)

cbwmin

59.9

·d

1.8

(9)

cbw

max =

192

·d

1.37

Page 26 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Table 4 Input data and ranges for facies simulation

The N/G ratio refers to the global net-to-gross ratio of sandy (porous) to non-porous rocks, in italic: corresponding parameters chosen after Gibling (2006)

a Based on the GR log of the E GrSk 3/90 borehole

b Estimated using the image log of E GrSk 3/90)

Unit Stratigraphy Modelled

reference

facies

Depth range

(m) (E GrSk

3/90)

Background

facies N/G ratioa

(dec) Main lithology Channel geometry: ranges, mean value in brackets

Orientationb

(°) Amplitude

(km) Wavelength

(km) Width (km) Thicknessb (m)

7 Upper Hanno-

ver Fm. (Mellin) (Sandy mudflat) 3875–3901 Mudflat playa 0.02 Mudstone Like sandy mudflat in unit 5

6 Hannover Fm.

(Mellin-Peck-

ensen)

Sandy mudflat 3901–3941 Mudflat playa 0.1 Mudstone,

siltstone, and

some sand-

stone

Like sandy mudflat in unit 5

5 Dethlingen to

Hannover Fm.

(Peckensen-

Eldena)

Sandy mudflat 3941–4084 Mudflat 0.4 Siltstone,

fine-grained

sandstone

275–360 (300) 0.8–2.5 (1.5) 1.0–5.0 (2.5) 0.005–0.4 (0.06) 0.2–8.0 (2.0)

4 Dethlingen Fm.

(Eldena) Epheremal

stream flood-

plain

4084–4134 Sandy mudflat 0.85 Siltstone,

fine-grained

sandstone

200–360 (290) 0.6–2.5 (1.7) 2.0–8.0 (4.0) 0.7–3.3 (2.1) 4.0–8.0 (6.0)

3 Dethlingen Fm.

(Rambow, ERS) Epheremal

stream flood-

plain

4134–4185 Sandy mudflat 0.99 Fine- to

coarse-grained

siltstone

225–340 (290)

2 Mirow Fm.

(Havel sub-

group)

Braided river 4185–4222 Sandy mudflat 0.8 Coarse-grained

sandstone and

conglomerate

290 ( -70)–90

(345) 0.6–2.5 (1.7) 2.0–8.0 (4.0) 2.5–4.5 (3.5) 8.0–12.0 (9.0)

1 Permo-Carbon-

iferous Tuffite, massive

andesite 4222–4292 None 0.85 Amygdaloidal

andesitic rocks 290 ( -70)–45

(355) – – Several km 0.3–7.0 (2)

Page 27 of 44

Nordenetal. Geothermal Energy (2023) 11:1

aeolian deposits. The estimation of the geometrical architecture of the stream flood-

plain based on borehole interpretation shown in Table4 is based on a mean bed thick-

ness and thickness deviation of 0.32m and 0.2m. Bar thicknesses, estimated from log

data, showed a range of 4–8m, giving some support for the interpretation. Based on

the higher resolution of the DAS–VSP seismic data, Martuganova etal. (2022) could

map a 20–30m thick horizon within the Dethlingen Formation, which they inter-

preted as a higher porous sandy reservoir section, possibly representing the seismic

visible part of a stacked channel architecture. However, internal channel structures

are not resolved by the data that is itself limited to the near-borehole area. We, there-

fore, use this information as a depth-related trend volume to guide the petrophysi-

cal modelling of the ERS, demanding for higher porosities in this zone (see also next

section).

The sandy mudflat and mudflat facies types of the Dethlingen and Hannover Forma-

tions were represented by finer siliciclastics, indicating the transition to the Zechstein

transgression. Borehole image logs are not available for this section. For the sandy

mudflat environment, siltstone and fine-grained sandstones are present which are

interpreted as deposits of sporadic higher current velocities in channel-like struc-

tures, assuming the architectural parameters presented in Table4 (inspired the range

for crevasse channels given by Gibling 2006). The mudflat facies finally consists of

mudstones of the playa environment without channels.

Petrophysical modelling

Permo‑Carboniferous volcanic rocks

The petrophysical properties of this sequence was evaluated based on the available

laboratory measurements of density, porosity, permeability, and log analysis (Table2,

Fig.11). Because only GR and Sonic logs and today only limited core material are availa-

ble for the lowermost section of the borehole, the core-log analysis of this section repre-

sents a first order estimate. The sonic-derived porosity will most likely overestimate the

connected porosity needed for the permeability estimation according to Siratovich etal.

(2014). However, the resulting permeability (brown “Perm volc.” line in Fig.11) shows

a quite reasonable match with the few values of laboratory-determined permeabili-

ties. Based on the estimated log permeability, its anisotropy was calculated as the ratio

between the harmonic and the arithmetic averages for 2-m depth intervals (see Table5).

In terms of petrophysical properties, the tuffite and the andesitic lava beds most likely

exhibit some differences (Fig.11) which could not be evaluated further based on the

available data quality. Total porosity (PHIT) of the igneous section was modelled facies-

dependent for the modelled layers based on the input data given in Table5. As a next

step, bulk density (RHOB), effective porosity of interconnected pores (PHIGE), and fluid

permeability (PERM) were simulated considering the PHIT distribution (using the collo-

cated co-Kriging function, see Table5). The thermal conductivity (TC) of the succession

was estimated by the approach of Garcíaet al. (1989) using the attributed PHIT and BD

distributions. A pT-correction was applied by cross correlation of the ambient and cor-

rected TC values from the log interpretation [TC(pT-corrected] = 0.8464 * TC + 0.3707].

The specific heat capacity (SHC) was calculated using the PHIT and RHOB distributions

Page 28 of 44

Nordenetal. Geothermal Energy (2023) 11:1

following the approach of Heap etal. (2020). Cross-correlation of T-corrected and ambi-

ent heat capacity from log analysis yield a simple correction function to correct the heat

capacity for in-situ conditions [SHC(T-corrected) = 1.237 * SHC − 0.01527]. Finally, the

in-situ thermal diffusivity (TD) of the igneous rocks was derived from the determined

properties with TD = [TC (pT-corrected)]/[SHC (T-corrected) * RHOB].

Sedimentary Rotliegend

For the evaluation of petrophysical properties, we could rely on the extensive data set of

the E GrSk 3/90 borehole (Table2, Fig.11). Permeability is shown from single borehole

logging (via pulsed-neutron logging, PNL) and based on implementation of the Coates

equation. The constants for the Coates relation are fitted manually, resulting in values of

750, 6, and 1.4, for a, b, and c, respectively. The derived Coates permeability log shows

a general agreement with the permeability estimated by the PNL, but in general a bet-

ter agreement with the in-situ corrected laboratory-derived permeability data (“Juhasz

corr.”, Fig.11). Three permeability measurements conducted under in-situ conditions

(Trautwein 2005) are plotted in Fig.11 (red dots), which seem to confirm the correction

Table 5 Input parameter used for petrophysical modelling of the volcanic rock section

Given is the range and mean (in brackets) chosen for the modelling and the supporting well-log and core data (if available)

with the respective standard deviation and the number of observations (in square brackets)

a Geometric mean with geometric standard deviation factor (GSD)

b Collocated co-Kriging with total porosity (PHIT) using a correlation coefficient of 0.8

c Collocated co-Kriging with total porosity (PHIT) using a correlation coefficient of − 0.8

d Input for a spherical variogram (given: major/minor/vertical [m], azimuth [°]). If not specified otherwise, all data refer to the

E GrSk 3/90 borehole, laboratory thermal data are corrected to in-situ conditions, see text

Tuffitic layers Andesitic lava beds

Model

parameter Well log data Model

parameter Well log data Core data

bed thickness

(m) 0.3–2.9 (1.4) Interpreted from

E GrSk 3/90 and

Gt GrSk 4/05

0.4–7.0 (2.2) Interpreted from E GrSk 3/90 and

Gt GrSk 4/05

PHIT (dec) 0–0.13

(0.05 ± 0.02) 0–0.13

(0.03 ± 0.03) [31] 0–0.11

(0.06 ± 0.02) 0–0.11

(0.04 ± 0.02)

[195]

–

PHIGEb (dec) 0–0.06

(0.02 ± 0.01) Not evaluated 0–0.08

(0.04 ± 0.01) Not evaluated 0 .03–0.06

(0.05 ± 0.01) [11]

BDc (kg/m3) 2420–2890

(2660 ± 120) 2422–2878

(2682 ± 84) [31] 2460–2830

(2640 ± 103) 2460–2763

(2623 ± 60) [195] 2580–2655

(2632 ± 28) [11]

PERM (m2) 0–8.9E−17

(9.90E−18) 1.77E−21

to 8.5E−16

(1.75E−19; GSD:

66, ranging from

2.66E−21 to

1.15E−17)a [31]

0–5.9E−17

(9.90E−18) 1.77E−21 to

6.11E−17

(4.83E−18; GSD:

4.3, ranging from

1.11E−18 to

2.09E−17)a [195]

0–1.38E−17

(4.9E−19; GSD:

17.4, ranging

from 2.82E−20 to

8.52E−18)a [10]

TC (Wm−1 K−1) 1.4–2.1

(1.9 ± 0.1) 1.5–1.9

(1.9 ± 0.1) [31] 1.6–2.1

(1.9 ± 0.1) 1.6–1.9

(1.9 ± 0.1) [195] 2.1 [1]

TD (10–6 m2s−1) 0.50–0.82

(0.69 ± 0.03) 0.58–0.78

(0.75 ± 0.05) [31] 0.55 –0.80

(0.69 ± 0.03) 0.61–0.78

(0.73 ± 0.04)

[195]

0.83 [1]

SHC (Jkg−1 K−1) 884–1195

(1021 ± 66) 888–1190

(981 ± 75) [31] 903–1154

(1030 ± 60) 920–1153

(1015 ± 47) [195] 976 [1]

Variogram inputd2000/1500/2,

330 – 2000/1500/3,

330 – –

Page 29 of 44

Nordenetal. Geothermal Energy (2023) 11:1

approach. The comparison of core and log data (Fig.12) shows roughly a similar distri-

bution, the paired quantile–quantile plot of the effective permeability shows, however,

that the log-derived permeability of permeabilities less than 10E−15 m2 (< 1mD) devi-

ates from the corrected core data, providing slightly higher permeabilities.

Anisotropy (calculated as the ratio between the harmonic and the arithmetic aver-

ages of log-derived permeability) ranges from 0.2 to 0.6 for a grid size of 1m, depend-

ing on the respective facies (Table6). TC, TD and SHC were determined from log

analysis according to Fuchs etal. (2015). TC was estimated on the combination of

the neutron-porosity (NPHI) log, the sonic log, and the gamma ray (Vshale) log

(Log_multi, Fig.11) as well using the bulk density (RHOB) and Vshale logs only (Log

RHOB/Vsh, Fig.11). TD (log_multi) is using RHOB, NPHI and Vshale log, while the

SHC was evaluated using RHOB, NPHI, and Vshale as input logs (the data and the

calculation is also provided in the data publication to this manuscript). In Fig.11,

the log-derived thermal properties are plotted together with the laboratory meas-

urements that were corrected to in-situ p/T-conditions. For TC, by applying the

Fig. 12 Histograms (a–d) and quantile–quantile plots (e, f) of total porosity (in %) and permeability (in mD)

for core data (a, b) and corresponding log-based data (c, d) for the stream floodplain facies of the EBS (E GrSk

3/90)

Page 30 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Table 6 Input parameter used for petrophysical modelling of the sedimentary Rotliegend

Braided plain fluvial Ephemeral stream floodplain Sandy mudflat Mudflat playa

Model Well log data Core data Model Well log data Core data Model Well log data Core data Model Well log data Core data

PHIT (dec) 0–0.16 (0.05) 0.01–0.08

(0.05 ± 0.01)

[120]

0.01–0.08

(0.04 ± 0.01)

[46]

0–0.21 (0.11) 0.03–0.20

(0.11 ± 0.05)

[395]

0.02–0.20

(0.12 ± 0.05)

[135]

0–0.17 (0.05) 0.01–0.07

(0.03 ± 0.01)

[189]

0.01–0.10

(0.04 ± 0.02)

[27]

0–0.18 (0.04) 0–0.16

(0.04 ± 0.02)

[684]

0.01–0.03

(0.02 ± 0.01) [11]

PHIGEb (dec) 0–0.05 (0.0) 0–0.03

(0.01 ± 0.01)

[120]

0–0.18 (0.08) 0–0.18

(0.05 ± 0.04)

[395]

0–0.11 (0.03) 0–0.05

(0.01 ± 0.01)

[189]

0–0.01 (0.0) < 0.01

BDc (kg/m3) 2510–2690

(2590)

2507–2688

(2589 ± 30)

[120]

2450–2680

(2567 ± 46)

[46]

2280–2690

(2450)

2283–2695

(2450 ± 83)

[395]

2110–2640

(2349 ± 128)

[135]

2510–2740

(2660)

2513–2740

(2653 ± 55)

[189]

2380–2700

(2569 ± 78)

[27]

2630–2750

(2710)

2343–2813

(2706 ± 38)

[686]

2660–2730

(2685 ± 17) [11]

Vshale (dec) 0.1–0.6 (0.2) 0.08–0.54

(0.28 ± 0.13)

[120]

– 0.01–0.5 (0.1) 0.01–0.52

(0.11 ± 0.09)

[395]

– 0.01–0.7

(0.3)

0.01–1.0

(0.35 ± 0.26)

[189]

– 0.01–0.8 (0.6) 0.02–0.79

(0.48 ± 0.13)

[686]

–

(Wm−1 K−1)

2.0–4.1

(3.7 ± 0.2)

2.8–3.9

(3.5 ± 0.3)

[109]

2.6–3.9

(3.2 ± 0.6) [7]

2.0–4.2

(3.6 ± 0.2)

2.9–4.1

(3.6 ± 0.2)

[395]

3.3–3.8

(3.5 ± 0.2) [18]

2.0–4.1

(3.2 ± 0.3)

1.7–4.1

(3.2 ± 0.6)

[189]

– 1.6–3.9

(2.2 ± 0.2)

1.9–3.9

(2.7 ± 0.3)

[686]

–

TD (10–6

m2s−1)

0.77–1.92

(1.67 ± 0.08)

1.32–1.75

(1.58 ± 0.12)

[120]

1.02–1.74

(1.50 ± 0.34)

[4]

0.78–1.91

(1.56 ± 0.15)

1.36–1.84

(1.56 ± 0.10)

[395]

1.14–1.61

(1.38 ± 0.19)

[6]

0.77–1.86

(1.49 ± 0.10)

0.89–1.83

(1.48 ± 0.24)

[189]

– 0.72–1.78

(1.04 ± 0.07)

0.92–1.79

(1.25 ± 0.14)

[686]

–

SHC

(Jkg−1 K−1)

750–1314

(846 ± 37)

736–961

(870 ± 52)

[120]

821–922

(871 ± 51) [4]

758–1314

(939 ± 88)

775–1384

(1089 ± 153)

[395]

878–1117

(977 ± 95) [6]

731–1314

(816 ± 36)

534–1080

(869 ± 102)

[189]

– 718–1314

(817 ± 60)

684–1350

(965 ± 81)

[686]

–

Page 31 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Given is the range and mean (in brackets) chosen for the modelling and the supporting well-log and core data (if available) with the respective standard deviation and the number of observations (in square brackets).

Vshale is calculated based on collocated co-Kriging with effective porosity (PHIGE) using a correlation coefficient of − 0.8 and the anisotropy of permeability is estimated for a vertical grid size of 1m. For annotations, see

Table5

Braided plain fluvial Ephemeral stream floodplain Sandy mudflat Mudflat playa

Model Well log data Core data Model Well log data Core data Model Well log data Core data Model Well log data Core data

PERM (m2) 6.57487E−09

PHIT8.237 [R2 of

PERM: 0.86]

8.71217E−23 to

9.08419E−18

(5.91676E−20;

GSD: 8, rang-

ing from

7.61256E−21 to

4.59873E−19)a

[120]

3.15459E−29

to 3.1554E−19

(2.87551E−22;

GSD: 52,

ranging from

5.49047E−24 to

1.50598E−20)a

[41]

2.17616E−08

PHIT8.421 [R2 of

PERM: 0.93]

4.90709E−21 to

2.34786E−13

(1.07351E−16;

GSD: 56,

ranging from

1.90643E−18

to 6.04E−15)a

[395]

3.57094E−23 to

1.09506E−13

(3.40634E−17;

GSD: 348,

ranging from

9.78739E−20 to

1.18552E−14)a

[70]

3.91314E-12

PHIT5.794 [R2 of

PERM: 0.61]

1.12819E−23 to

9.83741E−18

(4.6543E−20;

GSD: 3, rang-

ing from

2.81073E−21 to

7.70709E−19)a

[189]

5.03346E−22

to 3.08453E-19

(1.89941E−20;

GSD: 6, rang-

ing from

3.1455E−21 to

1.14695E−19)a

[14]

2.37058E−11

PHIT6.613 [R2 of

PERM: 0.86]

7.89834E−23 to

1.92197E−14

(2.79492E−19;

GSD: 6, rang-

ing from

4.77371E-20 to

1.63638E−18)a

[684]

6.72312E−22 to

5.39894E−20

(4.37607 + P26E

−21; GSD: 6,

ranging from6.

76601E

−22 to 2.88032E

−20)a [4]

Perm anisot-

ropy

0.6 0.4 0.2 0.2

Variogram

inputd500/250/5, 345 500/150/10, 290 1500/1000/5, 290 1500/1250/15, 300

Table 6 (continued)

Page 32 of 44

Nordenetal. Geothermal Energy (2023) 11:1

p-correction formula of Emirov etal. (2017) and the T-correction formula of Somer-

ton (1992), for SHC by applying the T correction given by Waples and Waples (2004),

and for estimating in-situ TD this properties is calculated based on the in-situ TC,

the temperature corrected SHC, and the respective laboratory-derived bulk density.

The log-derived values and the laboratory values show a very good agreement, allow-

ing parameterizing the sedimentary Rotliegend succession in a consistent manner.

To do so, we first addressed the total porosity (PHIT). Depending on the respective

facies, the PHIT distribution was modelled using the geostatistical input provided in

Table6. For the ERS, the seismic facies analysis of Bauer etal. (2020) and the DAS–

VSP analysis of Martuganova etal. (2022; for the near-borehole area only) were used

as additional trend information for the general probability of higher porosities in the

sandy reservoir section. PHIGE of this unit was modelled in relation to PHIT using the

collocated co-kriging algorithm of Petrel (Table6). For a representative and consist-

ent parameterization with permeability (PERM) and thermal properties, bulk density

(RHOB) of the rocks and the Vshale content were assigned to the grid cells. They were

simulated based on the distribution of PHIT (for RHOB) and of PHIGE (for VShale)

using the input parameters specified in Table 6. PERM was calculated on PHIT

(Table6) and in-situ TC and TD were estimated using the RHOB and Vshale distri-

butions based on the formulas [A55] and [B55] of Fuchs etal. (2015). Using the log

interpretation, the RHOB and Vshale-based TD was correlated with the NPHI, Vshale,

and RHOB-based TD. The SHC of the sedimentary section was calculated using the

estimated distributions of TC, TD, and RHOB according to SHC = TC/(TD * RHOB),

for details see data publication.

Figure13 illustrates the facies-dependent parameterization of the geological model,

addressing the mentioned petrophysical properties. In the vertical distribution of the

modelled properties, the Permo-Carboniferous volcanic rock sequence (unit 1) at the

model bottom shows clearly a layered character, low porosities and different thermal

properties than the overlying sedimentary units. The dense conglomeratic rocks of the

Mirow Formation (unit 2) show similar bulk densities as the volcanic rocks, but show

considerably different transient thermal properties compared to the adjacent model

units (Fig.13h, i). Unit 3 (Dethlingen Formation), containing the ERS, is most promi-

nent by showing higher permeabilities compared to the surrounding units. The forma-

tions above unit 3 are characterized by fine-grained sediments of playa and mud-flat

environments, resulting in higher shale content, lower specific heat capacities, and

with overall much poorer reservoir properties (Fig.13). Although the thickness of unit

3 is more or less constant along the section shown in Fig.13, the parameter of the

facies model provokes also some lateral and vertical variation in the property distribu-

tion. The lateral variation is also guided by the seismic facies analysis for the ERS, indi-

cating areas of higher porosity or thickness of the ERS. Figure14 shows the modelled

thickness and the distribution of PHIT, Vshale, PERM, and TC, guided by the seismic

facies analysis and the interpreted geophysical and laboratory data.

Page 33 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Discussion

The new 3D seismic of the Groß Schönebeck area (Fig.15) allows a more detailed inter-

pretation of the geological structures of the subsurface and provides a solid framework

for the site model building and its petrophysical parameterization.

Fig. 13 Facies (a) and petrophysical parameterization (b–i), assuming a thickness of the volcanic sequence

of about 200 m. Shown are 6.5 km long W–E cross sections covering the central part of the seismic survey in

the depth range of 3800–4400 m, located approximately 75–200 m north to the Groß Schönebeck boreholes

(views from the south). Exaggeration: approximately 1.5

Page 34 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Structural information

The structural interpretation shows some very distinct and clear features, like the salt

pillow distribution pictured by the pronounced Zechstein reflectors, and more ambig-

uous elements, such as the base and thickness of the Permo-Carboniferous volcanic

sequence.

Fig. 14 Analysis of the Elbe reservoir sandstone (ERS) derived from reservoir and seismic modelling. A

Seismic facies types in the EBS according to Bauer et al. (2020), B Thickness map of the EBS (unit 3 in the

geological model. Average property maps of the EBS showing total porosity (PHIT, C), shale content (Vshale,

D), permeability (mD, E), and thermal conductivity (TC, F). Superimposed are the borehole paths of the GrSk

boreholes (black lines in panel centres)

Fig. 15 Block visualizations of the new site and reservoir models of the Groß Schönebeck research platform,

view from south. The size of the site model is 10 km × 10 km, the size of the reservoir model 6.5 km × 6.5 km

Page 35 of 44

Nordenetal. Geothermal Energy (2023) 11:1

The top of the volcanic sequence is often well recognizable in seismic sections (Rieke

etal. 2001) due to their contrast in the acoustic behaviour of the overlying clastic Rotli-

egend sediments. However, the base could most often not be deciphered in seismic data.

Also for the Groß Schönebeck area, the base of the volcanic rocks could not be clearly

correlated with a seismic event. The top of Carboniferous as interpreted for the E GrSk

3/90 well was based on the geophysical log interpretation for the lowermost logged sec-

tion, postulating that the deepening of the E GrSk 3/90 well already drilled sedimentary

rocks of Carboniferous age (Holl etal. 2005). At a first glance, the results of Regenspurg

etal. (2016) seems to support this interpretation. They refer to geochemical analysis

of drill cuttings from the Gt GrSk 04/05 well which would classify the volcanic rock as

dacite or rhyodacite according to the TAS Diagram (Le Maitre 2002). These rock types

could relate to the first (oldest) eruption stage in Brandenburg and would, therefore,

support the interpretation that the sedimentary Carboniferous may be present close by.

However, further analysis performed on core samples of the correspondent depth inter-

val from the adjacent E GrSk 3/90 borehole classify the cored volcanic rock as andesite

(Lotz 2004). Thus, they may represent the latest eruption stage instead. An explanation

for this contradiction could result from a potential contamination of the drill cuttings

of the Gt GrSk 4/05 well. Due to a large open-hole section, the finely grounded cuttings

(not allowing to depict any rock fragments or structures) may be enriched with silica

minerals (quartz) from the sedimentary overburden. There are further indications that

the overall thickness of the volcanic sequence accounts for more than 70m. Bauer etal.

(2010) analysed seismic wide-angle data around the Groß Schönebeck site and modelled

a reflector in a depth of about 4.7km which is interpreted to correlate to the top of the

Pre-Permian. Taking the uncertainty in depth conversion and the different seismic data

types into account, this depth matches better to the lower C1 reflector (scenario B) with

a depth of about 4.4km than to the upper C1 reflector (scenario A) with a depth of about

4.2km. This upper C1 horizon may represent an internal feature of the volcanic suc-

cession (intermediate sedimentary layer or tuffite) rather than the top of the (sedimen-

tary) Carboniferous. Greater volcanic thicknesses were also expected by former studies.

Benek etal. (1996) and Benek and Hoth (2004) assumed a thickness of 200–400m for

the study area, a range that is also in agreement with legacy exploration data of the for-

mer GDR estimating a thickness of about 250m (Hoth and Huebscher 1986). The differ-

ent thickness scenarios will have an impact on the further site development. Therefore,

a proper seismic-well tie for the top of Carboniferous would be of high relevance. One

way to access these data could be achieved by deepening of the E GrSk 3/90 well by cor-

ing. Even if Carboniferous rocks were encountered, their characterization would allow

an optimized development of an EGS.

For the sedimentary Rotliegend, the 3D seismic provides evidence that faults with

large offsets are apparently absent in the study area. Based on the analysis, the Rotlieg-

end of the studied area does not show any segmentation into fault blocks. This is in con-

trast to the previous assumptions of a pronounced Rotliegend fault system in that area

(e.g., Moeck etal. 2009). The supposed faults, interpreted on re-processed 2D seismic

lines using complex attribute analysis, could not be confirmed by the 3D seismic vol-

ume. Thus, large and pronounced fault systems were not present in the data. Subseismic

joints are, however, expected. Interpretation of microseismic events due to hydraulic

Page 36 of 44

Nordenetal. Geothermal Energy (2023) 11:1

stimulations (Kwiatek etal. 2010) do suffer from the challenges in accurate location of

the events but give some ideas on the possible orientation of fault planes. The events,

however, do not coincide with structures within the seismic volume (Fig.16A). In this

context it is of interest that Blöcher etal. (2018) assume the existence of a fault along the

microseismic events, but they also state that they would expect seismic events for two

previously interpreted faults nearby the stimulated area, which did not occur. In con-

sequence, they questioned their existence. This interpretation, which is based on their

numerical model of coupled thermal–hydraulic–mechanical processes for accessing the

fault reactivation potential and its alteration during a waterfrac stimulation treatment, is

in agreement with the results from the geological interpretation of the 3D seismic sur-

vey, where no distinct faults could be mapped.

Our study allows some further information on the timing and evolution of the salt

pillow of Groß Schönbeck, which started in the Upper Buntsandstein and continues in

the Cretaceous to Cenozoic. The mapped graben structure at the top of the anticline

(related to the X3 horizon) are interpreted as internal Zechstein structures, resulting

Fig. 16 Examples of the high-resolution imaging achieved by the 3D seismics (Krawczyk et al. 2019),

targeting Permo-Carboniferous geothermal reservoirs in direct comparison with former investigations. A

Shows the micro-seismic events registered during fluid injection (Kwiatek et al. 2010) superimposed on

a cross section cut from the 3D seismics (Xline 2385, view from south), B and C show the 2D legacy lines

LEW25 (view from south) and LEW 1 (view from northeast) on the left-hand side, respectively (courtesy

Neptune Energy). For comparison, the corresponding sections cut from the new 3D seismics is shown on

the right. The arrow marks the projected drill site of Groß Schönebeck. Stippled lines show former fault

interpretations

Page 37 of 44

Nordenetal. Geothermal Energy (2023) 11:1

from broken anhydritic layers which were passed by more ductile rock salt. A similar

process is described by Strozyk etal. (2012) for the western Dutch offshore for the

so-called Z3 stringer (corresponding to the anhydrite of the Leine formation, reflec-

tor X2 to X3). This interpretation is also supported by the fact, that the post-Permian

reflectors do not show any distinct fault patterns in the 3D seismic. The uppermost

reflector that could be tracked more or less completely in the volume is the Jurassic

L2 reflector. The seismic to well-tie (Fig.5) relies on several types of input data and is

expected to represent a robust interpretation, especially for depths below 0.5–1km.

Comparing different time-to-depth conversions and former interpretations on legacy

seismic data, this uppermost depth level shows often slightly different correlations for

the seismic horizons. However, signal strength and resolution do not allow a detailed

interpretation of the structural and internal layering of post Jurassic strata. Former

interpretations based on one 2D seismic section reaching into the northwest of the

3D seismic area (e.g., LEW25/01, Figs.1, 16B, C) show some discontinuous reflectors

(courtesy of Neptune Energy). Due to the lower resolution of the 3D seismic at shal-

lower depths (the survey was designed to study the Permo-Carboniferous targets) and

the overall reduced seismic signal in that area, faults could not be tracked here. This

may indicate a somehow distorted layering of the strata with offsets below the seismic

resolution or just be related to a worse acoustic coupling due to higher thicknesses of

younger sediments with low densities. From surface studies, Hardt etal. (2021) inter-

pret Quaternary landforms to result from the interaction of glacial tectonics and halo

tectonics. Their location corresponds to the area, where the deep fracture is assigned

in the 3D seismic volume. Besides acoustic scattering triggered by a fracture system,

significant changes in the near-surface geology may represent another factor affecting

the quality of the seismic signal within the post-Permian. Figure17 shows the thick-

ness distribution of Quaternary sediments in the study area and the thickness of the

Tertiary Rupelton according to Stackebrandt and Manhenke (2010). In the north-

western part of the study area, a Quaternary incision trough cuts into the Tertiary

Rupelton allowing the deposition of more than 200m-thick unconsolidated Quater-

nary sediments, while the mean Quaternary sediment thickness in the remaining area

Fig. 17 Thickness maps of the Quaternary deposits (A) and of the Tertiary Rupelton (B) based on

Stackebrandt and Manhenke (2010). Superimposed in grey lines are the mapped main faults in the upper

Zechstein (this study) and the orientation of the seismic profile shown in C. C Seismic section of the pre-stack

depth migration volume with CRS stack after depthing (profile D in Fig. 6) showing less continuity of seismic

reflectors in the stippled area

Page 38 of 44

Nordenetal. Geothermal Energy (2023) 11:1

amounts to about 50–75m (Fig.17A). In the area of the incision trough, the seismic

signal is less pronounced like for the northern part of the seismic volume. However,

no deep fractures are observed in the Zechstein reflectors here. The Quaternary inci-

sion trough also reduces the thickness of the Tertiary Rupelton that shows a more

complex distribution (Fig.17B). The increased thickness of the Rupelton north of the

Groß Schönebeck drillsite coincides partly with the assumed fractured area and may

cause an additional damping of the seismic signal (Fig.17C). In general, the seismic

coverage decreases toward the surface, introducing some artefacts in the seismic vol-

ume and artificial discontinuities of the shallower seismic reflectors (Fig.5).

Facies interpretation andmodel parameterization

The modelled facies and parameter distribution is aiming to reflect a realistic scenario

of lateral and vertical structural and property distribution. The main restriction of

the model is that the interpretation of the sedimentary facies of the Rotliegend needs

to focus more or less on one location within the seismic volume (E GrSk 3/90 and Gt

GrSk 4/05 boreholes) and that the volcanic sequence is not characterized by the wells

completely.

The volcanic succession and a realistic property distribution is difficult to define. As the

top of the sedimentary Carboniferous could not be resolved with certainty, neither from

seismic or borehole data, this interpretation is lacking important input data. In addition, it

seems more realistic, that several volcanoes are building up this sequence, resulting also in

a more diverse flow and property distribution pattern of intercalated flows. Therefore, the

presented interpretation and parameterization of the volcanic sequence represents a first-

order approximation to enable further near-wellbore studies for site development, helping

in identifying possible layouts and related risks of hydraulic stimulations and in estimat-

ing the geothermal potential of this sequence. As stress in the subsurface is expected to

increase with depth, an upward fracture growth could be expected (see also Fig.5 in Zim-

mermann etal. 2010). By stimulating the volcanic rock sequence, the fracture will tend to

grow upward and may reach the overlying sedimentary Mirow Formation consisting of

conglomerates and sandstones. Kushnir etal. (2018) report in a study related to the Upper

Rhine Graben observations from outcrops showing that at the boundary to the crystalline

basement low-permeable and high-strength sedimentary rocks were present. These rocks

could also cap the crystalline basement hydraulically. In Groß Schönebeck, the petrophysi-

cal analysis of data from the E GrSk 3/90 borehole do indicate that the Mirow conglom-

erates above the volcanic succession exhibits a low matrix permeability. The hydraulic

and most likely the mechanical properties of the sedimentary and volcanic rocks may be

similar. The conglomerates, consisting of cemented volcanic rocks, show a similar poros-

ity as the volcanic rocks. A weaker formation is expected in the overlying sandy deposits

of the Dethlingen Formation, hosting the ERS. In the E GrSk 3/90 well, flow meter meas-

urements from a production test performed after deepening of the well and prior to stim-

ulation activities show some productive flow from an assumed natural fractured zone of

conglomeratic and volcanic rocks but no flow from the Dethlingen Formation (Tischner

etal. 2002). After a planned stimulation of the sandstones (isolated from the deeper con-

glomeratic and volcanic horizons by a sand pack), the productivity of the sandy interval was

not improved (Legarth etal. 2005). Instead, the productivity of the deeper conglomeratic

Page 39 of 44

Nordenetal. Geothermal Energy (2023) 11:1

horizon had increased, indicating that pre-existing fractures were most likely activated dur-

ing stimulation. This is supported by temperature measurements showing that the fluid

production temperatures are decreasing over time, documenting a hydraulic connection to

the overlying (cooler) sandy unit (Tischner etal. 2002). However, the real propagation of

induced fractures in Groß Schönebeck is not well constrained at all and may be triggered

by the occurrence of natural (sub-seismic) fracture networks (for details and discussion see

Blöcher etal. 2016). To design an adequate stimulation treatment of the volcanic Permo-

Carboniferous rocks, the real thickness and composition (the lateral and vertical hetero-

geneity) and the structural and geomechanical properties of this unit (massive andesite vs.

tuffitic layers) needs to be investigated in more detail. One option represents the deepening

of the E GrSk 3/90 borehole by coring and logging until proven Carboniferous rocks were

encountered.

The sedimentary Rotliegend could rely on a broader data set. Several boreholes nearby

give evidence on the principal composition and the development of the sedimentary envi-

ronment over time. The petrophysical well-log and core analysis reveals a profound facies-

dependency of petrophysical properties. Focusing on the permeability characterization,

the most robust correlation of porosity and permeability could be found in the ephemeral

stream facies. This is in agreement with the mineralogical composition of the correspond-

ing sandy reservoir: it represents a Quartz-dominated sandstone, and the permeability is

not strongly affected by clay minerals (Holl 2002). The proportion of clay minerals and their

textural properties plays a larger role for other sandy facies units, like the braided plains

or sandy mudflat environment. The derived in-situ fluid permeabilities for unit 5 (ERS)

ranges from less than 1mD (1E−15 m2) to more than 100mD (1E−13 m2), with an over-

all geometric mean of only some mD (Figs.13, 14). The analysis of well tests at the Groß

Schönebeck site (Blöcher etal. 2016) reports in the appendix transmissibility data of several

hydraulic tests conducted. If we assume a reservoir thickness of the EBS of roughly 40m at

the wellsite, corresponding field permeabilities were in the same order, showing values of

about 4mD (4E−15 m2).

Although the seismic data could not provide evidence for structural boundaries (block

or fault compartments), the result of the facies and parameter modelling shows for unit 5

(EBS) slightly reduced reservoir properties along the Gt GrSk 4/05 borehole (Fig.14). The

range of variation is covered by the expected geological heterogeneity. However, the recon-

struction of ancient fluvial system requires detailed information on its geometry in three

dimensions. Former realizations did not consider the natural heterogeneity of the Permian

reservoir but apply a layer-cake model of petrophysical properties, without consideration of

lateral variability (Blöcher etal. 2016). The presented new model will be used for reservoir

simulation, comparison, and future site development. First studies using a more realistic

heterogeneous parameterization inspired by this study show that this may lead to a signifi-

cant change in the long-term behaviour of the reservoir compared to a layer-cake model,

allowing a much faster breakthrough along preferred flow paths, requiring a different well

doublet layout. Moreover, the productivity of the system could be increased by an adapted

exploitation concept, considering a more realistic property distribution (Bohnen 2020).

Further enhancement of the presented model parameterization could be achieved

by inversion of the seismic data to better guide the distribution of petrophysical param-

eters. The inversion of the seismic volume may give some further insights on the property

Page 40 of 44

Nordenetal. Geothermal Energy (2023) 11:1

distribution patterns and reservoir heterogeneity. Nevertheless, the inversion will also be

limited by the scale and resolution of the geophysical (seismic) data and will not be able to

resolve a detailed geological facies pattern and the accompanied petrophysical properties

on a finer scale.

Conclusions

This work presents the results of an integrated study for reservoir characterization

of a long-lasting deep geothermal research platform Groß Schönebeck by integrat-

ing available geophysical and geological data. Reservoir characterization by geological

modeling is scale-sensitive. Integrating the available reconnaissance data with inter-

pretations from the new 3D seismic survey and the DAS–VSP data and the borehole

data allows constraining a much more realistic characterisation of the Rotliegend res-

ervoir of the Groß Schönebeck research platform across different scales. Based on

the structural data from 3D seismic and DAS–VSP geophysics as well as consider-

ing the geological (lithological and sedimentological) data from the boreholes, a

new site and reservoir model was set up, following a facies-dependent distribution

approach for its parameterization. In more detail, the new data allows a remapping

of the thickness of the sandy EBS reservoir zone and adjacent horizons and their res-

ervoir properties. The new 3D seismic data did not show any compartmentalization

of the Rotliegend reservoir at the Groß Schönebeck site. Also the cores of the E GrSk

3/90 borehole do not show extensive fracturing. Nevertheless, joints and small faults

of subtle and predominantly sub-seismic character may be present in the Rotliegend

reservoir target. The case study Groß Schönebeck shows that the geothermal explora-

tion of deep targets in the low-enthalpy setting should not rely solely on reconnais-

sance 2D-seismic lines, offset wells, and their (biased) structural interpretation. It is

necessary to include 3D seismic analysis and its integrated interpretation to allow a

more reliable site characterization and an adequate field development. Nevertheless,

direct information from boreholes is thereby a prerequiste for this method. The thick-

ness of the Permo-Carboniferous volcanic sequence, so far only indirectly deduced

from geophysical borehole logging in one well, could not be clearly confirmed by the

seismic data. To shed more light into the section below the sedimentary Rotliegend,

a deepening of the E GrSk 3/90 borehole, preferably by coring, would allow to judge

on the thickness and properties of the Permo-Carboniferous sequence. Further site

development could rely on deviated wells in the Rotliegend and Permo-Carboniferous

reservoirs with multi-stage stimulation to enhance the productivity of the reservoirs.

The provided in-depth characterization is forming the basis for an ongoing evaluation

of such and other exploitation strategies for the exploitation of deep geothermal res-

ervoirs in the Northeast German Basin.

Acknowledgements

We thank Neptune Energy for support and the permission to use legacy exploration borehole and seismic data (profiles

LEW) and the geological survey of Brandenburg (LBGR) for support in core sampling. We are grateful to Kristian Bär and

an anonymous reviewer for their constructive comments that helped improving the quality of the manuscript.

Author contributions

BN, KB, and CK analysed and interpreted the geological and seismic data, BN performed the geological modelling and

the facies and parameter parametrization of the reservoir targets, and was the major contributor writing the manuscript.

All authors read and approved the final manuscript.

Page 41 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Funding

Open Access funding enabled and organized by Projekt DEAL. The seismic survey was funded by the German Federal

Ministry for Economics within the project RissDom-A (Grant 0324065).

Availability of data and materials

The core and well-log data and applied analysis is provided in an accompanying data publication (Norden et al., 2022) at

the GFZ repository that also includes the main geological horizons and a populated simulation grid of the parameterized

reservoir model (https:// doi. org/ 10. 5880/ GFZ.4. 8. 2022. 013). The DAS–VSP data of Martuganova et al. (2022) is available

also via the GFZ repository (https:// doi. org/ 10. 5880/ GFZ.4. 8. 2022. 014). The 3D seismic data sets used and/or analysed are

available on request.

Declarations

Competing interests

The authors declare that they have no competing interests.

Received: 18 May 2022 Accepted: 18 December 2022

References

Allen JRL. Physical processes of sedimentation. London: Allen and Unwin; 1970.

Bauer K, Moeck I, Norden B, Schulze A, Weber M, Wirth H. Tomographic P-wave velocity and vertical velocity gradient

structure across the geothermal site Groß Schönebeck (NE German Basin): relationship to lithology, salt tectonics,

and thermal regime. J Geophys Res. 2010. https:// doi. org/ 10. 1029/ 2009J B0068 95.

Bauer K, Norden B, Ivanova A, Stiller M, Krawczyk CM. Wavelet transform-based seismic facies classification and model-

ling: application to a geothermal target horizon in the NE German Basin. Geophys Prospect. 2020. https:// doi. org/

10. 1111/ 1365- 2478. 12853.

Bełka Z, Devleeschouwer X, Narkiewicz M, Piecha M, Reijers TJA, Ribbert KH, Smith NJP. Devonian. In: Doornenbal JC,

Stevenson AG, editors. Petroleum geological atlas of the southern Permian Basin area. Houten: EAGE Publications;

2010. p. 71–9.

Benek R, Hoth P. Permokarbonische Vulkanite. In: Stackebrandt W, Manhenke V, editors. Atlas zur Geologie von Branden-

burg. Kleinmachnow: Landesamt für Geowissenschaften und Rohstoffe Brandenburg (LGRB); 2004. p. 80.

Benek R, Kramer W, McCann T, Scheck M, Negendank J, Korich D, Huebscher HD, Bayer U. Permo-carboniferous magma-

tism of the Northeast German Basin. Tectonophysics. 1996;266:379–404.

Beutler G, Franz M. Keuper. In: Stackebrandt W, Franke D, editors. Geologie von Brandenburg. Stuttgart: Schweitzerbart;

2015. p. 194–216.

Blöcher G, Reinsch T, Henninges J, Milsch H, Regenspurg S, Kummerow J, Francke H, Kranz S, Saadat A, Zimmermann G,

Huenges E. Hydraulic history and current state of the deep geothermal reservoir Groß Schönebeck. Geothermics.

2016. https:// doi. org/ 10. 1016/j. geoth ermics. 2015. 07. 008.

Blöcher G, Cacace M, Jacquey AB, Zang A, Heidbach O, Hofmann H, Kluge C, Zimmermann G. Evaluating micro-seismic

events triggered by reservoir operations at the geothermal site of Groß Schönebeck (Germany). Rock Mech Rock

Eng. 2018. https:// doi. org/ 10. 1007/ s00603- 018- 1521-2.

Bogie I, Mackenzie KM. The application of a volcanic facies model to an andesitic stratovolcano hosted geothermal

system at Wayang Windu, Java, Indonesia. In: 20th New Zealand geothermal workshop. 1998. https:// pangea. stanf

ord. edu/ ERE/ db/ IGAst andard/ record_ detail. php? id= 1827. Accessed 16 Feb 2022.

Bohnen B. Investigation of the influence of heterogenous reservoir properties on the productivity and sustainability of

the geothermal doublet system Groß Schönebeck. TU Berlin: master thesis; 2020.

Breitkreuz C, Geißler M. Permokarbonische Vulkanite. In: Stackebrandt W, Franke D, editors. Geologie von Brandenburg.

Stuttgart: Schweitzerbart; 2015. p. 110–6.

Bridge JS, Mackey SD. A theoretical study of fluvial sandstone body dimensions. Int Assoc Sedimentol Spec Publ.

1993;15:213–36.

Bridge JS, Tye RS. Interpreting the dimensions of ancient fluvial channel bars, channels, and channel belts from wireline-

logs and cores. Am Assoc Pet Geol Bull. 2000;84(8):1205–28.

Buness H, von Hartmann H, Rumpel H-M, Krawczyk CM, Schulz R. Fault imaging in sparsely sampled 3D seismic data

using common-reflection-surface processing and attribute analysis—a study in the Upper Rhine Graben. Geo-

phys Prospect. 2014. https:// doi. org/ 10. 1111/ 1365- 2478. 12099.

Coates GR, Peveraro RCA, Hardwick A, Roberts D. The magnetic resonance imaging log characterized by comparison

with petrophysical properties and laboratory core data. SPE Annu Tech Conf Exhib. 1991. https:// doi. org/ 10. 2118/

22723- MS.

DEKORP-BASIN Research Group. The deep crustal structure of the Northeast German basin: new DEKORP-BASIN’96 deep-

profiling results. Geology. 1999. https:// doi. org/ 10. 1130/ 0091- 7613(1999) 027% 3c0055: DCSOTN% 3e2.3. CO;2.

Doornenbal H, Stevenson A. Petroleum geological atlas of the southern Permian Basin area. Houten: EAGE Publications

BV; 2010.

Emirov SN, Beybalaev VD, Gadzhiev GG, Ramazanova AE, Amirova AA, Aliverdiev AA. To the description of the tem-

perature and pressure dependences of the thermal conductivity of sandstone and ceramics. J Phys Conf Ser.

2017;891:012335.

Franke D. Devon. In: Stackebrandt W, Franke D, editors. Geologie von Brandenburg. Stuttgart: Schweitzerbart; 2015a. p.

73–83.

Page 42 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Franke D. Flyschoides Karbon. In: Stackebrandt W, Franke D, editors. Geologie von Brandenburg. Stuttgart: Schweitzer-

bart; 2015b. p. 83–95.

Fuchs S, Förster A. Well-log based prediction of thermal conductivity of sedimentary successions: a case study from the

North German Basin. Geophys J Int. 2014. https:// doi. org/ 10. 1093/ gji/ ggt382.

Fuchs S, Balling N, Förster A. Calculation of thermal conductivity, thermal diffusivity and specific heat capacity of sedi-

mentary rocks using petrophysical well logs. Geophys J Int. 2015. https:// doi. org/ 10. 1093/ gji/ ggv403.

García A, Contreras E, Viggiano JC. Establishment of an empirical correlation for estimating the thermal conductivity of

igneous rocks. Int J Thermophys. 1989. https:// doi. org/ 10. 1007/ BF005 03174.

Gardner GHF, Gardner LW, Gregory AR. Formation velocity and density—the diagnostic basics for stratigraphic traps.

Geophysics. 1974. https:// doi. org/ 10. 1190/1. 14404 65.

Gast RE. 2.6 Sequenzstratigraphie. In: Plein E, editor. Stratigraphie von Deutschland I—Norddeutsches Rotliegendbecken,

Rotliegend-Monographie Teil II. Frankfurt: Courier Forschungsinstitut Senckenberg; 1995. p. 47–54.

Gast RE, Gebhardt U. 4.4 Elbe-Subgruppe. In: Plein E, editor. Stratigraphie von Deutschland I—Norddeutsches Rotlieg-

endbecken, Rotliegend-Monographie Teil II. Frankfurt: Courier Forschungsinstitut Senckenberg; 1995. p. 121–35.

Gast RE, Pasternak M, Piske J, Rasch H-J. Das Rotliegend im nordostdeutschen Raum: Regionale Übersicht, Stratigraphie,

Fazies und Diagenese. Geol Jahrb Reihe A. 1998;149:59–79.

Gast RE, Dusar M, Breitkreuz C, Gaupp R, Schneider JW, Stemmerik L, Geluk MC, Geisler M, Kiersnowski H, Glennie KW,

Kabel S, Jones NS. Rotliegend. In: Doornenbal JC, Stevenson AG, editors. Petroleum Geological Atlas of the South-

ern Permian Basin area. Houten: EAGE Publications; 2010. p. 101–21.

Gebhardt U, Schneider J, Hoffmann N. Modelle zur Stratigraphie und Beckenentwicklung im Rotliegenden der Nord-

deutschen Senke. Geol Jahrb Reihe a. 1991;127:405–27.

Geißler M, Breitkreuz C, Kiersnowski H. Late Paleozoic volcanism in the central part of the Southern Permian Basin (NE

Germany, W Poland): facies distribution and volcano-topographic hiati. Int J Earth Sci. 2008;97(5):973–89.

Gibling MR. Width and thickness of fluvial channel bodies and valley fills in the geological record: a literature compilation

and classification. J Sediment Res. 2006;76(5):731–70.

Hamann M, Kuhlee, Schulz W, Priebe. Geologisch-technisch-oekonomischer Abschlussbericht der Bohrung E Gross

Schönebeck 3/90, Erdoel-Erdgas Grimmen GmbH, Hauptabteilung Geologie, Grimmen, 24.5.1991, 66 pages and

11 enclosures. (in German).

Hardt J, Norden B, Bauer K, Toelle O, Krambach J. Surface cracks—geomorphological indicators for late Quaternary halo-

tectonic movements in northern Germany. Earth Surf Process Landf. 2021. https:// doi. org/ 10. 1002/ esp. 5226.

Heap MJ, Kushnir ARL, Vasseur J, Wadsworth FB, Harlé P, Baud P, Kennedy BM, Troll VR, Deegan FM. The thermal properties

of porous andesite. J Volcanol Geoth Res. 2020. https:// doi. org/ 10. 1016/j. jvolg eores. 2020. 106901.

Henninges J, Martuganova E, Stiller M, Norden B, Krawczyk CM. Wireline distributed acoustic sensing allows 4.2 km-deep

vertical seismic profiling of the Rotliegend 150°C-geothermal reservoir in the North German Basin. 2021. Solid

Earth. https:// doi. org/ 10. 5194/ se- 12- 521- 2021.

Holl HG. Clay minerals and cementation of clastic sediments of the Havel and Elbe Subgroups (Late Rotliegend) derived

from cores of the borehole Groß Schönebeck 3/90. In: Huenges E, Hurter S, editors. In-situ Geothermielabor Groß

Schönebeck 2000/2001. Scientific Technical Report STR02/14. 2002. https:// doi. org/ 10. 23689/ fidgeo- 522.

Holl HG, Moeck I, Schandelmeier H. Characterization of the tectono-sedimentary evolution of a geothermal reservoir—

implications for exploitation (Southern Permian Basin, NE Germany), (Proceedings), World Geothermal Congress

(Antalya Turkey). 2005. https:// www. geoth ermal- energy. org/ pdf/ IGAst andard/ WGC/ 2005/ 0614. pdf. Accessed 16

Feb 2022.

Hoth K, Huebscher H-D. Vulkanite der DDR (Lithologenetische und paläogeomorphologische Charakteristik sowie

Rayonierung der Autuneffussiva im Norden der DDR), VEB Geologische Forschung und Erkundung Freiberg, 1986.

Map 1:500.000. (in German).

Hoth K, Ruspült J, Zagora K, Beer H, Hartmann O. Die tiefen Bohrungen im Zentralabschnitt der Mitteleuropäischen

Senke - Dokumentation für den Zeitabschnitt 1962–1990, vol. 2. Berlin: Schriftenr geol Wiss; 1993. p. 145.

Huebscher H-D. Zur epigenetischen Metasomatose in den permosilesischen basaltischen Mg-Andesiten von Ost-

Brandenburg. Deutschland Terra Nostra. 1995;7:63–6.

Huenges E. Einleitung. In: Huenges E, Hurter S, editors. In-situ Geothermielabor Groß Schönebeck 2000/2001. Scientific

Technical Report STR02/14. 2002. https:// doi. org/ 10. 23689/ fidgeo- 522.

Huenges E, Hurter S, editors. In-situ Geothermielabor Groß Schönebeck 2000/2001. Scientific Technical Report STR02/14.

2002. https:// doi. org/ 10. 23689/ fidgeo- 522.

Huenges E, Winter H. Experimente zur Produktivitätssteigerung in der Geothermie-Forschungsbohrung Groß

Schönebeck 3/90, Scientific Technical Report, GeoForschungsZentrum Potsdam, STR 04/16; 2004. p.76–92. https://

doi. org/ 10. 48440/ gfz. b103- 04164. (in German).

Jakubowicz H. Wave equation prediction and removal of interbed multiples. In:68th annual international meeting, SEG,

expanded abstracts. 1998. https:// doi. org/ 10. 1190/1. 18202 04.

Juhasz I. Conversion of routine air permeability data into stressed brine-permeability data. In: SPWLA tenth European

formation evaluation symposium, Aberdeen, UK. 1986. p. 15.

Kana JD, Djongyang N, Raïdandi D, Nouck PN, Dadjé A. A review of geophysical methods for geothermal exploration.

Renew Sust Energy Rev. 2015. https:// doi. org/ 10. 1016/j. rser. 2014. 12. 026.

Klinkenberg LJ. The permeability of porous media to liquids and gases. Drill Prod Pract. 1941;2:200–13.

Kombrink H, Besly BM, Collinson JD, Den Hartog Jager DG, Drozdzewski G, Dusar M, Hoth P, Pagnier HJM, Stemmerik L,

Waksmundzka MI, Wrede V. Carboniferous. In: Doornenbal JC, Stevenson AG, editors. Petroleum geological atlas of

the southern Permian Basin area. Houten: EAGE Publications; 2010. p. 81–99.

König H, Meyer W. Ergebnisbericht Finow 2.1/Liebenwalde 2.1, VEB Kombinat Erdöl-Erdgas Gommern, 15.11.1988, p.35.

(in German).

Kopp J, Hoffmann N, Lindert W, Franke D. Präpermischer Untergrund - Tektonostratigraphie und Bruchstörungen. In:

Stackebrandt W, Manhenke V, editors. Atlas zur Geologie von Brandenburg. Kleinmachnow: Landesamt für Geow-

issenschaften und Rohstoffe Brandenburg (LGRB); 2004. p. 80.

Page 43 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Kossow D, Krawczyk CM. Structure and quantification of factors controlling the evolution of the inverted NE German

Basin. Mar Pet Geol. 2002;19(5):601–18.

Kossow D, Krawczyk CM, McCann T, Strecker M, Negendank JFW. Style and evolution of salt pillows and related structures

in the northern part of the Northeast German Basin. Int J Earth Sci. 2000;89(3):652–64.

Krawczyk CM, Henk A, Tanner DC, Trappe H, Ziesch J, Beilecke T, Aruffo CM, Weber B, Lippmann A, Görke U-J, Bilke L,

Kolditz O. Seismic and sub-seismic deformation prediction in the context of geological carbon trapping and stor-

age. Adv Technol Earth Sci. 2015. https:// doi. org/ 10. 1007/ 978-3- 319- 13930-2_5.

Krawczyk CM, Stiller M, Bauer K, Norden B, Henninges J, Ivanova A, Huenges E. 3-D seismic exploration across the deep

geothermal research platform Groß Schönebeck north of Berlin/Germany. Geotherm Energy. 2019. https:// doi.

org/ 10. 1186/ s40517- 019- 0131-x.

Kushnir ARL, Heap MJ, Baud P, Gilg A, Reuschlé T, Lerouge C, Dezayes C, Duringer P. Characterizing the physical proper-

ties of rocks from the Paleozoic to Permo-Triassic transition in the Upper Rhine Graben. Geotherm Energy. 2018.

https:// doi. org/ 10. 1186/ s40517- 018- 0103-6.

Kwiatek G, Bohnhoff M, Dresen G, Schulze A, Schulte T, Zimmermann G, Huenges E. Microseismicity induced during fluid-

injection: a case study from the geothermal site at Groß Schönebeck, North German Basin. Acta Geophys. 2010.

https:// doi. org/ 10. 2478/ s11600- 010- 0032-7.

Lange G, Söllig A, Tessin R, Berlin ZGI. Isobathen der Zechsteinbasis 1:500.000. VEB Kartographischer Dienst Potsdam,

Zentrales Geologisches Institut, Berlin; 1981.

Le Maitre RW. Igneous rocks: a classification and glossary of terms. Cambridge: Cambridge University Press; 2002. p. 252.

Leclair SF, Bridge JS. Quantitative interpretation of sedimentary structures formed by river dunes. J Sediment Res.

2001;71(5):713–6.

Legarth B, Huenges E, Zimmermann G. Hydraulic fracturing in a sedimentary geothermal reservoir: results and implica-

tions. Int J Rock Mech Min Sci. 2005. https:// doi. org/ 10. 1016/j. ijrmms. 2005. 05. 014.

Lindert W, Warncke D, Stumm M. Probleme der lithostratigraphischen Korrelation des Oberrotliegenden (Saxon) im

Norden der DDR. Z Angew Geol. 1990;36(10):368–75.

Lokhorst A. NW European gas atlas. Haarlem: Nederlands Inst. voor Toegepaste Geowetenschappen TNO. 1 CD-ROM;

1998.

Lotz B. Neubewertung des rezenten Wärmestroms im Nordostdeutschen Becken. Potsdam: Scientific Technical Report

04/04. 2004. http://d- nb. info/ 97155 8531/ 34. Accessed 16 Feb 2022.

Mann J, Jäger R, Müller T, Höcht G, Hubral P. Common-reflection-surface stack—a real data example. J Appl Geophys.

1999. https:// doi. org/ 10. 1016/ S0926- 9851(99) 00042-7.

Martuganova E, Stiller M, Norden B, Henninges J, Krawczyk CM. 3D deep geothermal reservoir imaging with wireline

distributed acoustic sensing in two boreholes. 2022. Solid Earth. https:// doi. org/ 10. 5194/ se- 2021- 138.

McCann T. Sandstone composition and provenance of the Rotliegend of the NE German Basin. Sediment Geol.

1998;116(3–4):177–98.

McGuire JJ, Lohman RB, Catchings RD, Rymer MJ, Goldman MR. Relationships among seismic velocity, metamorphism,

and seismic and aseismic fault slip in the Salton Sea Geothermal Field region. J Geophys Res Solid Earth. 2015.

https:// doi. org/ 10. 1002/ 2014J B0115 79.

Mendrinos D, Choropanitis I, Polyzou O, Karytsas C. Exploring for geothermal resources in Greece. Geothermics. 2010.

https:// doi. org/ 10. 1016/j. geoth ermics. 2009. 11. 002.

Moeck I, Schandelmeier H, Holl HG. The stress regime in a Rotliegend reservoir of the Northeast German Basin. Int J Earth

Sci. 2009. https:// doi. org/ 10. 1007/ s00531- 008- 0316-1.

Norden B, Bauer K, Krawczyk CM. Input and resulting structural and parameterized subsurface data for a geological

model of the geothermal research platform Groß Schönebeck (North German Basin). GFZ Data Services. 2022.

https:// doi. org/ 10. 5880/ GFZ.4. 8. 2022. 013.

Peryt TM, Geluk MC, Mathiesen A, Paul J, Smith K. Zechstein. In: Doornenbal JC, Stevenson AG, editors. Petroleum geo-

logical atlas of the southern Permian Basin area. Houten: EAGE Publications; 2010. p. 123–47.

Plein E. Stratigraphie von Deutschland I - Norddeutsches Rotliegendbecken, Rotliegend-Monographie Teil II. Frankfurt:

Courier Forschungsinstitut Senckenberg; 1995.

Pussak M, Bauer K, Stiller M, Bujakowski W. Improved 3D seismic attribute mapping by CRS stacking instead of NMO

stacking: application to a geothermal reservoir in the Polish basin. J Appl Geophys. 2014. https:// doi. org/ 10. 1016/j.

jappg eo. 2014. 01. 020.

Regenspurg S, Feldbusch E, Norden B, Tichomirowa M. Fluid-rock interactions in a geothermal Rotliegend/Permo-

Carboniferous reservoir (North German Basin). Appl Geochem. 2016. https:// doi. org/ 10. 1016/j. apgeo chem. 2016.

03. 010.

Reinhardt H-G. Structure of Northeast Germany: regional depth and thickness maps of Permian to Tertiary intervals

compiled from seismic reflection data. Spec Publ Eur Assoc Pet Geosci. 1993;3:155–65.

Ricard LP, Huddlestone-Holmes CR, Pujol M. Reservoir and production engineering challenges for geothermal systems

hosted in Australian Sedimentary Basins. Soc Pet Eng. 2016. https:// doi. org/ 10. 2118/ 182343- MS.

Rider M. The geological interpretation of well logs. Caithness: Whittles Publ; 2000. p. 280.

Rieke H. Sedimentologie, Faziesarchitektur und Faziesentwicklung des kontinentalen Rotliegenden im Norddeutschen

Becken (NEDB). Potsdam: Scientific Technical Report STR 01/14. 2001. https:// doi. org/ 10. 48440/ GFZ. b103- 010029.

Rieke H, Kossow D, McCann T, Krawczyk CM. Tectono-sedimentary evolution of the northernmost margin of the NE Ger-

man Basin between uppermost Carboniferous and Late Permian (Rotliegend). Geol J. 2001;36(1):19–37.

Rieke H, McCann T, Krawczyk CM, Negendank JFW. Evaluation of controlling factors on facies distribution and evolution

in an arid continental environment: an example from the Rotliegend of the NE German Basin. In: McCann T, Sain-

tot A, editors. Tracing tectonic deformation using the sedimentary record. Geol Soc Spec Publ. 2003;208:71–94.

Rockel W, Hurter S. Tiefe Altbohrungen als Beitrag zur Nutzbarmachung klüftig-poröser Speichergesteine (geologische

Grundlagen): Groß Schönbeck. Scientific Technical Report STR00/23. 2000. p. 29–50. https:// doi. org/ 10. 48440/ gfz.

b103- 00236. (in German).

Page 44 of 44

Nordenetal. Geothermal Energy (2023) 11:1

Scheck M, Bayer U. Evolution of the Northeast German Basin—inferences from a 3D structural model and subsidence

analysis. Tectonophysics. 1999;313(1–2):145–69.

Scheck M, Bayer U, Lewerenz B. Salt movements in the Northeast German Basin and its relation to major post-Permian

tectonic phases—results from 3D structural modelling, backstripping and reflection seismic data. Tectonophysics.

2003;361(3–4):277–99.

Scheck-Wenderoth M, Maystrenko Y, Hübscher C, Hansen M, Mazur S. Dynamics of salt basins. In: Littke R, Bayer U, Gajew-

ski D, Nelskamp S, editors. Dynamics of complex sedimentary basins. The Central European basin system. Berlin:

Springer; 2008. p. 307–22.

Sekiguchi KA. A method for determining terrestrial heat flow in oil basinal areas. Tectonophysics. 1984;103:67–79.

Siler DL, Faulds JE, Mayhew B, McNamara DD. Analysis of the favorability for geothermal fluid flow in 3D: Astor Pass

geothermal prospect, Great Basin, northwestern Nevada. USA Geotherm. 2016. https:// doi. org/ 10. 1016/j. geoth

ermics. 2015. 11. 002.

Siratovich PA, Heap MJ, Villenueve MC, Cole JW, Reuschlé T. Physical property relationships of the Rotokawa Andesite, a

significant geothermal reservoir rock in the Taupo Volcanic Zone, New Zealand. Geotherm Energy. 2014. https://

doi. org/ 10. 1186/ s40517- 014- 0010-4.

Somerton WH. Thermal properties and temperature-related behavior of rock/fluid systems. Amsterdam: Elsevier Science

Publishers; 1992.

Stackebrandt W, Manhenke V. Atlas zur Geologie von Brandenburg. Cottbus: Landesamt für Bergbau, Geologie und

Rohstoffe; 2010.

Stackebrandt W, Röhling HG. Trias – Geologischer Rahmen. In: Stackebrandt W, Franke D, editors. Geologie von Branden-

burg. Stuttgart: Schweitzerbart; 2015. p. 144–7.

Strozyk F, Van Gent H, Urai JL, Kukla PA. 3D seismic study of complex intra-salt deformation: an example from the Upper

Permian Zechstein 3 stringer, western Dutch offshore. Geol Soc Spec Publ. 2012. https:// doi. org/ 10. 1144/ SP363. 23.

Strozyk F, Reuning L, Scheck-Wenderoth M, Tanner DC. Chapter 10—The tectonic history of the Zechstein Basin in the

Netherlands and Germany. In: Soto JI, Flinch JF, Tari G, editors. Permo-triassic salt provinces of Europe, North Africa

and the atlantic margins. Amsterdam: Elsevier; 2017. p. 221–41.

Tischner T, Thorenz C, Jung R, Kessels W. Results from a production test: hydraulics. In: Huenges E, Hurter S, editors. In-situ

Geothermielabor Groß Schönebeck 2000/2001. Scientific Technical Report STR02/14. 2002. https:// doi. org/ 10.

23689/ fidgeo- 522.

Trautwein U, Huenges E. Poroelastic behaviour of physical properties in Rotliegend Sandstones under uniaxial strain,

Internat. J Rock Mech Min Sci. 2005;42(7–8):924–32.

Trautwein U. Poroelastische Verformung und petrophysikalische Eigenschaften von Rotliegend Sandsteinen. Berlin: Dis-

sertation TU Berlin. 2005. https:// depos itonce. tu- berlin. de/ bitst ream/ 11303/ 1537/1/ Dokum ent_ 47. pdf. Accessed

16 Feb 2022.

van Wees J-D, Stephenson RA, Ziegler PA, Bayer U, McCann T, Dadlez R, Gaupp R, Narkiewicz M, Bitzer F, Scheck M. On the

origin of the Southern Permian Basin, Central Europe. Mar Pet Geol. 2000;17:43–59.

von Hartmann H, Beilecke T, Buness H, Musmann P, Schulz R. Seismische exploration für tiefe Geothermie. Geol Jahrb.

2015;B104:1–271.

Waples DW, Waples JS. A review and evaluation of specific heat capacities of rocks, minerals, and subsurface fluids. Part 1:

minerals and nonporous rocks. Nat Resour Res. 2004. https:// doi. org/ 10. 1023/B: NARR. 00000 32647. 41046. e7.

Wyllie MRJ, Gregory AR, Gardner LW. Elastic wave velocities in heterogeneous and porous media. Geophysics. 1956;21(1):41–70.

Zhang X, Hu Q. Development of geothermal resources in China: a review. J Earth Sci. 2018. https:// doi. org/ 10. 1007/

s12583- 018- 0838-9.

Zhang Y, Krause M, Mutti M. The formation and structure evolution of Zechstein (Upper Permian) salt in Northeast Ger-

man basin: a review. Open J Geol. 2013. https:// doi. org/ 10. 4236/ ojg. 2013. 38047.

Ziegler PA. Geological atlas of western and Central Europe. 2nd ed. The Hague: Shell; 1990.

Zimmermann G, Moeck I, Blöcher G. Cyclic waterfrac stimulation to develop an enhanced geothermal system (EGS)—

conceptual design and experimental results. Geothermics. 2010. https:// doi. org/ 10. 1016/j. geoth ermics. 2009. 10.

003.

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