Conditions for Generation, Accumulation, and Preservation of Oil and Gas in Permian Strata, Northwestern Anabar–Khatanga Oil and Gas Region

Abstract

Abstract —Integrated seismic, drilling, and generalizing scientific research in the southeastern Anabar–Khatanga oil and gas region (OGR) since the early 1930s led to discoveries of small oil and gas occurrences and one large Central Olgino oil field. However, the petroleum potential of the northwestern part of the region remains poorly investigated and evaluated. To assess the prospects for the oil and gas potential of this territory, all seismic and geological and geochemical information was used, including four new wells drilled in the Sopochnoe uplift and the Zhuravliny swell. The scales of oil and gas formation, accumulation and destruction of hydrocarbon accumulations in the Permian deposits, which are the most promising in terms of the initial potential of the source rocks included in their composition, is given. The source rocks of the Upper Kozhevnikovo, Lower Kozhevnikovo, and Tustakh formations have been characterized in terms of thickness, contents of organic carbon and chloroform bitumen, maturity (catagenesis) of organic matter, and density of oil migration and gas generation. The maximum possible estimates of oil and gas resources that can potentially accumulate in structural traps, without migration losses, are obtained for each of the three reservoir formations by basin modeling. Judging by geological and geochemical criteria, the Upper Kozhevnikovo Formation can preserve only a minor portion of initially accumulated hydrocarbons, while the oil and gas accumulations, as well as the petroleum generation potential of organic matter in the Lower Kozhevnikovo and Tustakh formations, were destroyed by late Permian–Early Triassic trap magmatism and Mesozoic–Cenozoic tectonic activity.