The Gt BTrKoe 1/2021 borehole was drilled in the framework of a research project called GeoFern, funded by the German Ministry for Economic Affairs and Climate Action under the grant number 03EE4007. The overall objective of this research project was to support the development of the geothermal heat utilization for urban areas. Therefore, the integration of reservoir utilization concepts into heat supply systems need to be studied. The GeoFern project aimed to contribute to the knowledge on geological structure and the lithological composition of the subsurface to minimize the explorational risks for future site developments in SE Berlin, Germany. It focused on the exploration of possible Mesozoic aquifers, suitable for aquifer thermal energy storage (ATES) in depths of up to 500 m. As stopping criteria for drilling, the presence of terrestrial (arid) clayey Keuper sediments of the Exter Formation (Upper German Triassic) were defined.
In this data publication we provide the results of the investigations and measurements conducted on site in the field laboratory as well as the open-hole geophysical well-logging data of the Gt BTrKoe 1/2021 borehole acquired by a commercial contractor. In addition, a temperature log of the borehole, measured by the GFZ about two months after the end of drilling activities, is part of this data publication.
The drilling of the Gt BTrKoe 1/2021 borehole started at the 15th of November 2021 with the setting of the conductor pipe and reached its final depth of 456 m in Triassic sediments on the 19th of December 2021. The drilling was conducted in two main sections using two different technologies. For the upper section, covering Cenozoic sediments and reaching a depth of 211 m, reverse drilling technology was used. This section comprises the Quaternary to Tertiary groundwater system and the Tertiary “Rupelton” (Oligocene, Rupelian). The latter represents an about 100 m thick clayey succession that do act as a regional aquitard, separating the deeper saline groundwater systems from the upper utilized (freshwater) groundwater levels. After setting and cementing of the casing, the borehole was further deepened by using conventional Rotary drilling technology. Due to the lack of knowledge on the geological situation of the pre-Cenozoic strata before the drilling, this section represents the most relevant part for answering the research goals of the project. In order to allow the most accurate description and characterization of the drilled strata, this section was completely cored using wireline coring equipment with 3-m core barrels. In total, 90 core runs were conducted and 197.4 m of cores retrieved, showing a core recovery factor of 81%. The core show a mean core diameter of about 100 mm. The drilling was stopped after encountering the multicolored terrestrial playa sediments of the Upper Triassic in the last core run.
While the token cutting samples were not assigned with International Generic Sample Numbers (IGSN), the borehole (Norden, 2022) and all taken cores were registered with IGSNs.
South Wales is characterised by a rich variety of geologic formations and rocks of different ages and periods, and a large asymmetric syncline, as perhaps its most significant structural geological feature, extending from east to west over a length of approximately 96 km and 30 km from north to south, respectively. This oval-shaped syncline is part of the Variscan orogenic thrust and fold belt in Central Europe and covers some 2,700 km2, with coal-bearing rocks from the Upper Carboniferous (Westphalian Stage) deposited in the central syncline and older rocks outcropping in a peripheral belt around it. The coal-bearing sequence begins with Namurian grits and shales, overlain by the more productive Lower, Middle and Upper Coal Measures. A 3D structural geological model has been implemented for the central part of the South Wales Syncline and its bedrock geology. The oldest rocks in the model domain date back to the Pridoli Series from the uppermost Silurian, the youngest to the Westphalian Stage of the Upper Carboniferous. For model implementation, mainly open access data from the British Geological Survey (BGS) has been used.
The final 3D structural geological model covers the entire Central South Wales Syncline and is 32.8 km wide and 36.6 km long. In total, the 3D model includes 21 fault zones and the elevation depth of ten surfaces: (1) Top Upper Coal Measures Formation; (2) Top Middle Coal Measures Formation; (3) Top Lower Coal Measures Formation; (4) Top Millstone Grit Group; (5) Top Dinantian Rocks; (6) Top Upper Devonian Rocks; (7) Top Lower Devonian Rocks (sandstone dominated); (8) Top Lower Devonian Rocks (mudstone dominated); (9) Top Pridoli Rocks; (10) Top Ludlow Rocks (in parts).
The Mallik Anticline is a geologic structure in the Mackenzie Delta in the Canadian Arctic. Tectonics throughout the Cenozoic, with compressional phases in the early Eocene to the late Miocene, formed this large, domed structure that is today an important source of hydrocarbons. Gas hydrates occur in the clastic sedimentary rocks of the Oligocene to Pleistocene Kugmallite, Mackenzie Bay, and Iperk sequences, which were essentially formed by deltaic processes. The presence of hydrocarbon gases within the permafrost zone in the Canadian Arctic has led to extensive exploration and production activities in the region since the mid-1960s, and the investigations by geologists and geophysicists have already been published in numerous scientific articles to date.
The associated report (Chabab and Kempka, 2023) describes the implementation of the first field-scale 3D static geologic model of the Mallik site, which was created using data from well logs and 2D seismic reflection profiles. The dataset presented here provides elevation depths and thickness data of the three distinct sequence boundaries Kugmallit-Richards, Mackenzie Bay-Kugmallit and Iperk-Mackenzie Bay as well as fault data from the Mallik site.