Sverre Ekrene Ohm1,2, Leif Larsen3, Snorre Olaussen1, Kim Senger1, Thomas Birchall14, Thomas Demchuk5, Andrew Hodson1, Ingar Johansen6, Geir Ove Titlestad7, Dag A. Karlsen4 and Alvar Braathen1,4 are the authors of the article “Discovery of shale gas in organic-rich Jurassic successions, Adventdalen, Central Spitsbergen, Norway”, recently published in the Norwegian Journal of Geology.
1Department of Arctic Geology, The University Centre in Svalbard; 2Department of Energy Resources, University of Stavanger; 3KAPPA Engineering, Norway; 4Department of Geosciences, University of Oslo; 5RPS Group Inc, USA; 6Institute for Energy Technology, Norway; 7Gotic AS, Norway.
Thermogenic dry gas flowed from Jurassic sections in the DH5R research well drilled onshore in Adventdalen, central Spitsbergen, Arctic Norway. The DH5R gas originates from the organic-rich units of the mudstone-dominated Middle Jurassic to Lower Cretaceous Agardhfjellet Formation, which is the onshore equivalent to the Fuglen Formation and the prolific oil and gas generating Hekkingen Formation in the southern Barents Shelf. Low-permeable, low-porosity sandstones from the Upper Triassic De Geerdalen Formation of the neighbouring DH4 well were oil-stained and gas was also collected from this interval. Gas from the two stratigraphic intervals have different compositions; the gas from the Agardhfjellet Formation is drier and isotopically heavier than the gas from the Upper Triassic succession. Both gases originated from source rocks of maturity near the end of the oil window (1.1 < Ro < 1.4% Ro). Maceral analyses of the Agardhfjellet Formation indicate that the more silty parts contain a high percentage of vitrinite-rich type III kerogen, whereas the clay-dominated parts are rich in liptinitic type II kerogen. The Agardhfjellet Formation has therefore the potential to generate both oil and gas. Several simulations based on pressure data and flow rates from the DH5R well were run to evaluate if the gas accumulation in the Agardhfjellet Formation is producible, i.e., can it be commercial shale gas. The models demonstrate how changes in the drainage area size and form, well types (vertical versus horizontal), number and length of induced fractures and thickness of the Agardhfjellet Formation affect gas production rates and producible volumes. Despite uncertainties in the input data, simulations indicate that the shale gas accumulation characterised in Adventdalen is producible. This gas can have major environmental benefits as an alternative for local power generation compared to coal.
Keywords: Thermogenic gas, Svalbard, shale gas, unconventional, permafrost, maturation, pressure, stable isotopes.
Ohm, S.E.; Larsen, L.; Olaussen, S.; Senger, K.; Birchall, T.; Demchuk, T.; Hodson, A.; Johansen, I.; Titlestad, G.O.; Karlsen, D.A.; Braathen, A. (2019): Discovery of shale gas in organic-rich Jurassic successions, Adventdalen, Central Spitsbergen, Norway. Norwegian Journal of Geology 99. DOI: 10.17850/njg007. [intranet]