Abstract

This work presents the results of geological and geochemical studies of organic matter of source rocks and oil from reservoirs in the Karamay Formation (Anisian–Ladinian stages) in the eastern part of the Fukang Sag in the Junggar petroleum basin. The quantity, quality, and a degree of maturity of the organic matter in clayey mudstones in the upper part of the Karamay Formation (T₂k) were considered and the composition of original organic matter including conditions of its accumulation and a degree of maturity were reconstructed using pyrolytic parameters and biomarkers. The dark gray and gray mudstone in the upper part of the Karamay Formation accumulated in fresh or low salinity lakes with relatively reducing conditions of sedimentation. At present, the organic matter of the Formation within the sag occurs in the zone of mesocatagenesis MK₁–MK₃, therefore, its generation potential has been realized unevenly. It has been previously established that mudstones in the upper part of the Karamay Formation provide hydrocarbon fluids for the Karamay reservoirs located in the submerged part of the eastern slope of the Fukang Sag.