Porosity–permeability relationship derived from Upper Jurassic carbonate rock cores to assess the regional hydraulic matrix properties of the Malm reservoir in the South German Molasse Basin

A comprehensive hydrogeological understanding of the deep Upper Jurassic carbonate aquifer, which represents an important geothermal reservoir in the South German Molasse Basin (SGMB), is crucial for improved and sustainable groundwater resource management. Water chemical data and environmental isotope analyses of D, 18O and 87Sr/86Sr were obtained from groundwater of 24 deep Upper Jurassic geothermal wells and coupled with a few analyses of noble gases (3He/4He, 40Ar/36Ar) and noble gas infiltration temperatures. Hierarchical cluster analysis revealed three major water types and allowed a hydrochemical zoning of the SGMB, while exploratory factor analyses identified the hydrogeological processes affecting the water chemical composition of the thermal water. Water types 1 and 2 are of Na-[Ca]-HCO3-Cl type, lowly mineralised and have been recharged under meteoric cold climate conditions. Both water types show 87Sr/86Sr signatures, stable water isotopes values and calculated apparent mean residence times, which suggest minor water-rock interaction within a hydraulically active flow system of the Northeastern and Southeastern Central Molasse Basin. This thermal groundwater have been most likely subglacially recharged in the south of the SGMB in close proximity to the Bavarian Alps with a delineated northwards flow direction. Highly mineralised groundwater of water type 3 (Na-Cl-HCO3 and Na-Cl) occurs in the Eastern Central Molasse Basin. In contrast to water types 1 and 2, this water type shows substantial water-rock interaction with terrestrial sediments and increasing 40Ar/36Ar ratios, which may also imply a hydraulic exchange with fossil formation waters of overlying Tertiary sediments.

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Geothermal play typing in Germany, case study Molasse Basin: a modern concept to categorise geothermal resources related to crustal permeability

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/njg.2019.12 ◽

2019 ◽

Vol 98 ◽

Author(s):

Inga S. Moeck ◽

Michael Dussel ◽

Josef Weber ◽

Tom Schintgen ◽

Markus Wolfgramm

Keyword(s):

Heat Transport ◽

Carbonate Rock ◽

Upper Jurassic ◽

Carbonate Reservoir ◽

General Idea ◽

Modern Concept ◽

Molasse Basin ◽

Geothermal Resources ◽

Porosity And Permeability ◽

Type Concept

Abstract The majority of running geothermal plants worldwide are located in geological settings with convection- or advection-dominant heat transport. In Germany as in most regions in Europe, conduction is the dominating heat transport mechanism, with a resulting average geothermal gradient. The geothermal play type concept is a modern methodology to group geothermal resources according to their geological setting, and characteristic heat transport mechanisms. In particular, the quantity of heat transport is related to fluid flow in natural or engineered geothermal reservoirs. Hence, the permeability structure is a key element for geothermal play typing. Following the existing geothermal play type catalogue, four major geothermal play types can be identified for Germany: intracratonic basins, foreland basins and basement/crystalline rock provinces as conduction-dominated play types, and extensional terrains as the convection-dominated play type. The installed capacity of geothermal facilities sums up to 397.1 MWth by the end of 2018. District heating plants accounted for the largest portion, with about 337.0 MWth. The majority of these installations are located in the play type ‘foreland basin’, namely the Molasse Basin in southern Germany. The stratigraphic unit for geothermal use is the Upper Jurassic, also known as ‘Malm’ formation, a carbonate reservoir with high variability in porosity and permeability. Recently drilled wells in the southernmost Molasse Basin indicate the Upper Jurassic as a tight, fracture-controlled reservoir, not usable for conventional hydrothermal well doublets. Our new data compilation including the recently drilled deep geothermal well Geretsried reveals the relation of porosity and permeability to depth. The results suggest that obviously diagenetic processes control permeability with depth in carbonate rock, diminishing the predictability of reservoir porosity and permeability. The play type concept helps to delineate these property variations in play type levels because it is based on geological constraints, common for exploration geology. Following the general idea of play typing, the results from this play analysis can be transferred to geological analogues as carbonate rock play levels in varying depth.

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Using hydrochemical and environmental isotope data to characterize the thermal reservoir of the Upper Jurassic aquifer in the South German Molasse Basin on the Pleistocene timescale

10.7185/gold2021.5010 ◽

2021 ◽

Author(s):

Theis Winter ◽

Florian Einsiedl

Keyword(s):

Upper Jurassic ◽

Molasse Basin ◽

The South ◽

Environmental Isotope ◽

Thermal Reservoir ◽

Isotope Data

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S-wave experiments for the exploration of a deep geothermal carbonate reservoir in the German Molasse Basin

Geothermal Energy ◽

10.1186/s40517-021-00189-w ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Britta Wawerzinek ◽

Hermann Buness ◽

Hartwig von Hartmann ◽

David C. Tanner

Keyword(s):

Upper Jurassic ◽

Carbonate Reservoir ◽

P Wave ◽

Seismic Survey ◽

Seismic Exploration ◽

Molasse Basin ◽

S Wave ◽

Induced Earthquakes ◽

Conversion Point ◽

Facies Classification

AbstractThere are many successful geothermal projects that exploit the Upper Jurassic aquifer at 2–3 km depth in the German Molasse Basin. However, up to now, only P-wave seismic exploration has been carried out. In an experiment in the Greater Munich area, we recorded S-waves that were generated by the conventional P-wave seismic survey, using 3C receivers. From this, we built a 3D volume of P- to S-converted (PS) waves using the asymptotic conversion point approach. By combining the P-volume and the resulting PS-seismic volume, we were able to derive the spatial distribution of the vp/vs ratio of both the Molasse overburden and the Upper Jurassic reservoir. We found that the vp/vs ratios for the Molasse units range from 2.0 to 2.3 with a median of 2.15, which is much higher than previously assumed. This raises the depth of hypocenters of induced earthquakes in surrounding geothermal wells. The vp/vs ratios found in the Upper Jurassic vary laterally between 1.5 and 2.2. Since no boreholes are available for verification, we test our results against an independently derived facies classification of the conventional 3D seismic volume and found it correlates well. Furthermore, we see that low vp/vs ratios correlate with high vp and vs velocities. We interpret the latter as dolomitized rocks, which are connected with enhanced permeability in the reservoir. We conclude that 3C registration of conventional P-wave surveys is worthwhile.

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Tectono-magmatic reactivation of Téfidet Cretaceous trough during Cenozoic (Aïr, Niger)

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.187.2.73 ◽

2016 ◽

Vol 187 (2) ◽

pp. 73-82 ◽

Cited By ~ 2

Author(s):

Yacouba Ahmed ◽

Moussa Konaté ◽

Moussa Harouna

Keyword(s):

Volcanic Activity ◽

Upper Jurassic ◽

South Atlantic ◽

The South ◽

Lake Chad ◽

Pan African ◽

The Relationship ◽

Extension Period

AbstractThe Téfidet trough (eastern Niger) belongs to the Ténéré megasystem set of Cretaceous rifts N130°E to N170°E oriented, corresponding to the direction of the Lake Chad-Hoggar tectonic axis.The study of the relationship between the structure of the trough and alkaline fissural volcanism that developed there from the Oligocene to Plio-Quaternary shows the uniqueness of the Téfidet trough compared to the neighboring contemporary volcanic areas of Hoggar, Cameroon, and southern Aïr.The tectono-magmatic reactivation of the Cretaceous Téfidet trough developed in two steps: – a period contemporaneous with the Tuareg shield bulging (Aïr, Hoggar, Iforas);– a subsequent extension period generally N060°E, which has persisted since the opening of the South Atlantic (upper Jurassic to Plio-Quaternary).The fissural volcanism, due to the reactivation of Pan African and Cretaceous faults evolved concomitantly with the N060°E extension (syn-magmatic micro-fractures with basaltic filling), in several steps, from Oligocene to Plio-Quaternary.This study highlights the existence of periods of quietness and recovery of volcanic activity, for which two assumptions can be made: – no enough absolute datings,– apolyphased extension of the rift.The latter hypothesis seems to be supported by three periods of volcanic quietness, 28–24 m.y., 20–14 m.y. and 8–5 m.y., observed in the northern and the southern Aïr, Gréboun and Todgha, respectively.

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Tectonic reconstruction of Uda-Murgal arc and the Late Jurassic and Early Cretaceous convergent margin of Northeast Asia–Northwest Pacific

Stephan Mueller Special Publication Series ◽

10.5194/smsps-4-273-2009 ◽

2009 ◽

Vol 4 ◽

pp. 273-288 ◽

Cited By ~ 9

Author(s):

S. D. Sokolov ◽

G. Ye. Bondarenko ◽

A. K. Khudoley ◽

O. L. Morozov ◽

M. V. Luchitskaya ◽

...

Keyword(s):

Northeast Asia ◽

Upper Jurassic ◽

Island Arc ◽

Passive Margin ◽

Northwest Pacific ◽

Island Arcs ◽

The South ◽

Convergent Margin ◽

Tectonic Zone ◽

The North

Abstract. A long tectonic zone composed of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks is recognized along the Asian continent margin from the Mongol-Okhotsk fold and thrust belt on the south to the Chukotka Peninsula on the north. This belt represents the Uda-Murgal arc, which was developed along the convergent margin between Northeast Asia and Northwest Meso-Pacific. Several segments are identified in this arc based upon the volcanic and sedimentary rock assemblages, their respective compositions and basement structures. The southern and central parts of the Uda-Murgal arc were a continental margin belt with heterogeneous basement represented by metamorphic rocks of the Siberian craton, the Verkhoyansk terrigenous complex of Siberian passive margin and the Koni-Taigonos Late Paleozoic to Early Mesozoic island arc with accreted oceanic terranes. At the present day latitude of the Pekulney and Chukotka segments there was an ensimatic island arc with relicts of the South Anyui oceanic basin in a backarc basin. Accretionary prisms of the Uda-Murgal arc and accreted terranes contain fragments of Permian, Triassic to Jurassic and Jurassic to Cretaceous (Tithonian–Valanginian) oceanic crust and Jurassic ensimatic island arcs. Paleomagnetic and faunal data show significant displacement of these oceanic complexes and the terranes of the Taigonos Peninsula were originally parts of the Izanagi oceanic plate.

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Le synclinal danien-eocene de La Mourotte (Var)

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.s7-iv.1.87 ◽

1962 ◽

Vol S7-IV (1) ◽

pp. 87-91 ◽

Cited By ~ 3

Author(s):

Fernand Touraine

Keyword(s):

Upper Jurassic ◽

The South ◽

Northern Limit ◽

Southern Limit ◽

The North ◽

Bird Eggs ◽

Tectonic Study ◽

Dinosaur Eggs

Abstract Results of a stratigraphic and tectonic study of the Mourotte syncline, Provence, France, divide the structure into three parts. The northern part is composed of Hauterivian littoral beds containing Danian dinosaur eggs. The Danian limestone-sandstone series disappears at La Neuve while the marly upper Danian beds continue to the extreme northern limit of the syncline. In the central part the Hauterivian wedges out, and toward its southern limit the substratum is entirely upper Jurassic. In the southern part, the Danian limestones are only visible on the northeast border. Bird eggs collected in the area assign the southern part of the syncline to the Thanetian. Overturning is less noticeable in the north, becoming acute toward the south where the syncline is tightly overturned.

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