烃源岩有限空间油气生排模拟及其意义

利用DK-Ⅱ型地层孔隙热压生排烃模拟实验仪,对东濮凹陷沙三2亚段烃源岩开展烃源岩有限空间油气生排模拟研究,结果揭示烃源岩的生排烃演化呈现出4个阶段,即烃源岩在Ro值小于等于0.72%的阶段为相对缓慢生油阶段,生成的油无法排出;R_o值介于0.72%～0.80%之间的阶段为烃源岩快速生油阶段,但生成的油仍主要残留于烃源岩中;在R_o值为0.80%～1.00%时干酪根生油已结束或受到抑制,主要表现为大分子"油"向小分子"油"转化,该阶段油可以排运在烃源岩上、下邻接的砂岩层以及烃源岩表面及裂缝内,这为东濮凹陷及其他盆地或凹陷在以烃源岩为主体的发育带寻找非常规油气藏提供了依据;在R_o值大于1.00%时主要进入油裂解成气阶段,但即使在R_o为2.0%甚至2.4%时,生成的油也没有全部裂解成甲烷气,主要还是以油的形式存在,启示可以打破传统认识在更深的层位寻找石油。 

Simulation of source rock for hydrocarbon generation and expulsion in finite space and its significance

Simulation of source rock for hydrocarbon generation and expulsion in finite space has been carried out with samples from the Es23 sub-section of the Dongpu sag using the hydrocarbon generation and expulsion simulation experimental instrument of type DK-Ⅱ with porosity,temperature and pressure under geological conditions.It has been concluded that the process of hydrocarbon generation and expulsion of source rock can be divided into 4 stages as follows.1) Ro≤0.72%,oil generates slowly and does not expel;2) 0.72%1.0%,oil cracks to gas;however,oil does not crack to CH4 completely and mainly remains in oil even though Ro>2.0% or 2.4%.The studies suggest that petroleum exploration can be carried out in deeper formation.