不同类型优质烃源岩生排油气模式

Hydrocarbon generation and expulsion pattern of different types of excellent source rocks

利用地层孔隙异常压力热模拟实验分别对硅质型、钙质型与粘土型优质烃源岩进行分析,生排油气模拟结果表明:(1)成熟早中期硅质型优质烃源岩排油量与排油效率最高,早期主要以重质油排出为主,排油效率高达50%左右;钙质型优质烃源岩次之,排烃效率一般在30%左右;粘土型优质烃源岩排油效率一般只有4%～11%。(2)在成熟中晚期,硅质型优质烃源岩排油效率最高,但是钙质型烃源岩增加迅速达65%,粘土型烃源岩增加不明显。(3)成熟晚期—高成熟阶段,硅质型和钙质型优质烃源岩排油效率变化不明显,而粘土型烃源岩排油效率则从20%迅速增加到90%。硅质型、钙质型和粘土型优质烃源岩生排油气模式之间最大的差异是它们在成熟早中期排油效率和排油量不同。

Semi-closed pyrolysis experiments were conducted in order to evaluate what controls the hydrocarbon generation and expulsion efficiency for three types of excellent source rocks （siliceous, calcareous and clay ones）. Each type of source rock has different relative hydrocarbon expulsion efficiencies in the stage of early- middle oil window, where siliceous source rock has the highest oil expulsion efficiency and oil expulsion quanti- ty, reaching to 50%, and the expelled products are dominated by heavy oil. This is followed by calcareous source rock, about 30%. The oil expulsion efficiency of clay source rock is the lowest, about 4%-11%. During the middle-late maturation stage, siliceous source rock tends to achieve the highest expulsion efficiency first, fol- lowed by calcareous source rock （65%） and then clay source rock. During the late and high-mature stage, the oil expulsion efficiencies of siliceous and calcareous source rocks do not change obviously, while the oil expulsion efficiency of clay source rock increases rapidly from 20% to 90%. The models of hydrocarbon generation and ex- pulsion of three types of excellent source rocks are different in the stage of early-middle oil window.