oa The Phase, Origin and Maturity of Condensate and Wet Gas Reservoirs in the Western Kuqa Depression, Tarim Basin

The petroleum system in the northern Kuqa Depression, Tarim Basin is a lacustrine-coal-petroleum in a tectonically complex foreland basin developed in the ancient craton area. The phase distribution of the petroleum fluid is unclear and the origin and maturity of light oil and condensate are not well studied. We mapped and profiled the phase and physical distribution, characterized the source rock, investigated the origin of the light oil using biomarkers and isotopes, and analyzed the gas geochemistry and the effects on origin and maturity using kinetic simulations. From the oil profile and distribution, the heavy oil found is spatially coincident with the dry gas, which is due to the source rock, mixing of oil and gas, and subsequent gas washing. The light oil is mainly from J2q and the gases are mainly from coal rock with a strong mixture of helium and CO2. The ratio of Tol/(MCH+Tol) can be effectively used to evaluate the maturity of light oil, and the diagram of gas isotopes calibrated by pyrolysis can be used to calculate the maturity of gases. The mixture of different maturated oil and gases from two sources forms the assembly of oil and gases in this area.