吐哈盆地三叠系小泉沟群泥质烃源岩排烃门限及排烃特征模拟研究

MODELING STUDIES ON THRESHOLD AND CHARACTERISTICS OF HYDROCARBON EXPULSION FROM MUDDY SOURCE ROCKS OF TRIASSIC IN XIAOQUANGOU ARER OF TURPAN HAMI BASIN

应用排烃门限控油气理论并结合盆地模拟 ,对吐哈盆地小泉沟群泥质烃源岩排烃门限和排烃特征进行了研究。研究结果表明 ,在地史埋深过程中 ,小泉沟群泥质烃源岩分别约于 3 .5 ,4 .0和 4 .5km处进入甲烷气、重烃气和液态烃排出门限 ,排烃阶段为 :水溶扩散相排气→游离相排气→游离相排油气。天然气主要以水溶、扩散、油溶和游离 4种相态排运 ,其中 ,水溶相和扩散相所占比例分别超过 3 5 %和 2 0 %。排出油中水溶相和扩散相约占 3 0 % ,游离相不到 70 %。现今 ,1m3源岩中甲烷气、重烃气和液态烃的排出量分别为 0 4m3,0 18m3和 0 16kg ,三者的排出效率分别为 3 2 % ,2 6%和 2 4 %左右。

The theory of hydrocarbon expulsion threshold (HET) and basin simulation are applied to study on the characteristics of hydrocarbon expulsion from muddy source rocks of Triassic in Xiaoquangou area of Turpan Hami basin. In the process of burial, source rocks of Xiaoquangou group first reached the methane expulsion threshold, then the heavy gas expulsion threshold, and finally the liquid hydrocarbon expulsion threshold at the depths of 3.5, 4.0 and 4.5 km, respectively. The process for hydrocarbon expulsion can be divided into three stages: gas expulsion in water solution, gas expulsion by diffusion, and gas expulsion in free phase. The gas expulsion is mainly in the phases of water solution, diffusion, oil solution and free phase. Among them, the ratios of water solution and diffusion exceed 35% and 20% respectively while that in oil solution is about 10%, and that in free phase is less than 20%. The ratio for oil expulsion in water solution and by diffusion is about 30% while that in free phase is less than 70%. Currently, the amounts for methane, heavy gas and oil expelled from 1 m 3 source rocks of Xiaoquangou group are 0.4 m 3, 0.18 m 3, 0.16 kg, while the corresponding expulsion efficiencies are about 32%, 26%, 24%, respectively.