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应用排烃门限控油气理论 ,对吐哈盆地台北凹陷侏罗系煤源岩排烃过程进行了数值模拟。模拟结果表明 ,研究区煤源岩在埋深 5 0 0m左右同时进入排甲烷气、排重烃气门限 ,并于 2 0 0 0m左右进入排液态烃门限。在埋深为 35 0 0m左右达到排烃高峰。现今 1m3 源岩排出的甲烷气、重烃气和液态烃量分别为 6 4.72m 3、3.82m 3和 34 .97kg。煤源岩主要以水溶、扩散、油溶和游离四种相态排运油气 ,其中油溶相和游离相起决定作用。甲烷气、重烃气和液态烃的排出效率分别为 73.5 %、6 6 .1%和 6 9.9%。排烃过程可划分为三个阶段 :水溶—扩散相初始排气阶段、早期游离相大量排气阶段和中期游离相大量排液态烃阶段 ,为三阶段多相态排油气地质模式。
The hydrocarbon expulsion process of the Jurassic coal source rocks in the Taipei depression of the Turpan-Hami Basin is numerically simulated using the hydrocarbon-expulsion threshold-controlled oil and gas theory. The simulation results show that the coal source rocks in the study area enter the methane gas at the same time with a depth of about 500m, displace the hydrocarbon gas threshold, and enter the threshold of liquid hydrocarbon at about 2000m. In the depth of about 35 0 0m to reach the peak of hydrocarbon excretion. The methane, heavy hydrocarbon and liquid hydrocarbons discharged from 1m3 source rocks are 6 4.72m 3, 3.82m 3 and 34.97kg respectively. Coal-derived rocks mainly distribute oil and gas in four phases: water-soluble, diffusive, oil-soluble and free, in which oil-soluble phase and free-phase play a decisive role. The discharge efficiencies of methane, heavy hydrocarbon and liquid hydrocarbons were 73.5%, 66.1% and 69.9%, respectively. The process of hydrocarbon expulsion can be divided into three stages: initial stage of water-dissolving-diffusing phase, large amount of early stage of free phase and large amount of phase of hydrocarbon in the middle stage of free phase, which is a three-phase multiphase model.