Potential hydrocarbon Source Rocks of the Barents Sea (including Svalbard) and the East-Greenland-Shelf – Geochemical investigations associated with the Projects PANORAMA and CASE (2016)
Report of the project:
In the framework of the BGR project PANORAMA the hydrocarbon generation potential of sediments of the European Arctic and risks of tentative production activities in this region are evaluated. Detailed knowledge of distribution, depth and thickness of potentially hydrocarbon generating sediments (source rocks) is integral in understanding the energy resource potential. Geochemical parameter, such as total organic carbon content and thermal maturity, control the amount and type of hydrocarbons (oil or gas) that a source rock can generate, or already generated in the past. Scientists in BGR’s division „Organic Geochemistry and Gas Geochemistry“ work on the geochemical characterization of hydrocarbon source rocks and base their evaluation on literature data, data from BGR archives, as well as on results of geochemical analyses performed at BGR’s laboratories. Best geochemical results can be achieved by analysis of samples obtained from wells drilled into the targeted source rock formations. For the northern Barents Sea and East Greenland Shelf area, however, no source rock samples from deep boreholes are available. In these cases, samples collected from outcrops on the Svalbard archipelago and along the coast of East Greenland, respectively, are studied as analogues for source rocks in the off-shore study area.
Paleogeographic situation of the northern Barents Sea during Middle Triassic ca. 245 million years before present (after Dallmann, 2015). The excellent hydrocarbon source rocks of the Botneheia und Steinkobbe Formations were deposited during this time on a shallow to deep shelf
Source: Dallmann, 2015
Potential hydrocarbon source rocks in the northern Barents Sea are sediments of the Middle Triassic Botneheia Formation and the Late Jurassic to Early Cretaceous Agardhfjellet Formation. Other source rocks in focus of this study are Arctic coals of Carboniferous (Billefjorden Group) and Paleocene (Firkanten Formation) age, which have a high potential to generate hydrocarbons.
During BGR’s CASE program land expeditions are carried out frequently to study the structural history of the Arctic. Based on rock samples collected during CASE expeditions, extensive and detailed geochemical analyses are performed for the source rock characterization and obtained results are organized in a geographic information system for further evaluation among the Panorama project.
Sample collection of organic-rich mudstones of the Botneheia Formation at the name-giving Botneheia on Spitsbergen during the CASE 17 expedition in summer 2015. The cliff-forming calcitic sediments in the upper part belong to the Blanknuten Member
Source: BGR
Additional to routine organic geochemical methods such as determination of total organic carbon content and analysis of hydrocarbon generation potential by Rock-Eval pyrolysis, reaction kinetic parameters are obtained from open and closed system pyrolyses experiments. Source rock kinetics are crucial for petroleum systems modeling to assess whether hydrocarbons were generated in sedimentary basin in the Arctic. Respective data are gained from combining temperature programmed open-system pyrolysis with isotope ratio mass spectrometry and the analysis of the stable isotope composition of hydrocarbons, generated during pyrolysis.
Source: BGR
Other aspects of the Panorama project are the test of related geochemical methods (Blumenberg et al., 2018) and the analysis of gases bound in near-surface marine sediment. These so-called “adsorbed” gases are released from sediments samples in the laboratory and can provide information on hydrocarbon accumulations in underlying deeper sediments (Faber et al., 1997). Results of an expedition to the Arctic Ocean north of Svalbard (Panorama-1) indicate that in the area of the southern Nansen Basin Paleocene source rocks, most likely deposited during the Eocene, occur at sufficient depth for hydrocarbon generation (Blumenberg et al., 2016). Similar work on sediments from the Storfjorden- and Olga-Basins (Northern Barents Sea) indicate, in terms of maturity and hydrocarbon generation potential, other hydrocarbon source rocks in respective target areas (Weniger et al., 2017).
Literature:
Blumenberg, M., Lutz, R., Schlömer, S., Krüger, M., Scheeder, G., Berglar, K., Heyde, I., Weniger, P., 2016. Hydrocarbons from near-surface sediments of the Barents Sea north of Svalbard – Indication of subsurface hydrocarbon generation? Marine and Petroleum Geology 76, 432-443.
Blumenberg, M., Pape, T., Seifert, R., Bohrmann, G., Schlömer, S., 2018. Can hydrocarbons in entrapped in seep carbonates serve as gas geochemistry recorder? Geo-Marine Letters 38, 121–129.
Dallmann, W.K., 2015. Geoscience Atlas of Svalbard. Norwegian Polar Institute, Tromsø.
Faber, E., Berner, U., Hollerbach, A., Gerling, P., 1997. Isotope geochemistry in surface exploration for hydrocarbons. Geologisches Jahrbuch D103, 103-127.
Weniger, P., Berglar, K., Blumenberg, M., Erhardt, A., Franke, D., Klitzke, P., Lutz, R. (2017) Near-surface gas geochemistry of the Northern Barents Sea. 28th International Meeting on Organic Geochemistry (IMOG), Florence, Italy 17-22 September.
Weniger, P., Blumenberg, M., Berglar, K., Ehrhardt, A., Klitzke, P., Krüger, M. and Lutz, R. (2019) Origin of near-surface hydrocarbon gases bound in northern Barents Sea sediments. Mar. Petrol. Geol. 102, 455-476; https://doi.org/10.1016/j.marpetgeo.2018.12.036