Some characteristics of oil and gas accumulation in the Kuqa depression, Tarim basin

Abstract: There exist 6 sets of hydrocarbon source rocks with a great gas generation potential in the Kuqa depression, which provide plenty of gas for gas accumulation in the depression. Tectonic movements generated a series of fractures, which get the deep gas source rocks connected and provide good conduits for the migration of natural gas from deep source rocks to reservoirs. Due to the influence of many factors, the phase states of oil and gas in the Kuqa depression are of very uneven distribution. Multiple phases of petroleum accumulation occurred in the Kuqa depression, but the last phase was the most important. Gas accumulation occurred relatively late in the Kuqa depression. The Kuqa depression mainly yields gas; however, a part of oil deposits or oil and gas deposits are residual ones, which is the result of diffusion of large amounts of gas. Because of the difference in preservation conditions between the Kuqa depression and the Turpan-Hami basin, the Kuqa depression is gas-prone while the Turpan-Hami basin is oil-prone.