Accumulation characteristics and controlling factors of the Tugeerming gas reservoir in the eastern Kuqa Depression of the Tarim Basin, northwest China

Abstract

Because of the huge potential of hydrocarbon, the Jurassic strata in the Tugeerming area has become a significant exploration target in the Kuqa Depression of the Tarim Basin. However, accumulation characteristics and controlling factors for the Tugeerming gas reservoir need to be further developed. In the present study, the accumulation characteristics were discussed using geochemical techniques, and the controlling factors for the generation and accumulation of gas reservoir were summarized. The gas generation intensity in Tugeerming reservoir is about 20–60 × 108 m3/km2, suggesting that source rocks could generate sufficient natural gas for the reservoir. Sandstone reservoirs with relatively good physical properties (Improved by fractures and dissolution) provide favorable condition for the gas accumulation. This oil charging period of the Early Neogene (N1j) and the gas charging period of the Pliocene (N2k) occurred in the reservoir and the periods were 23–8 Ma and 5.2–1.64 Ma, respectively. Continuous production of natural gas is beneficial to accumulation. Faults and fractures provide migration channels for oil and gas. Fractures optimize the physical properties of the reservoir. Moreover, the assemblages of source–reservoir–caprock in Tugeerming area provided good condition for hydrocarbon preservation. Tugeerming gas reservoir is defined as a structure–lithologic type, which is lower generation and upper storage mode. The conclusions are critical to further oil and gas exploration.