鄂尔多斯盆地上三叠统延长组低渗透岩性油藏成藏物理模拟

晚三叠世延长期鄂尔多斯为陆相坳陷盆地,主要发育湖泊三角洲相沉积,油藏主要为低-特低渗透岩性油藏。研究表明,长7生烃作用形成的异常高压是石油向低渗透储层运移的主要动力,运移方式主要为幕式运移。通过成藏物理模拟手段分析不同压力条件下低渗透成藏过程及成藏特征,同时对比不同注入压力、不同充注方向下幕式成藏特征及与稳态成藏的差异。实验结果表明,无论烃源岩向上还是向下排烃,异常压力越大越有利于低渗透储层成藏,成藏效率越高,含油饱和度越高。

Physical simulation of hydrocarbon accumulation in low-permeability lithologic reservoirs: an example from the Yanchang Formation in the Upper Triassic of the Ordos Basin

In the late Triassic Yanchang period,the Ordos Basin was a continental depression basin.The deposits of lake-delta facies are prevalent,and hydrocarbon reservoirs are mainly low-and ultra-low-permeability litholo-gic type.A research into the area reveals that the abnormally high pressure resulted from hydrocarbon generation in the Chang-7 Formation serves as the major dynamic force for the episodic migration of oil toward low-permeability reservoirs.Physical simulation was performed to analyze the process and features of hydrocarbon accumulation in low-permeability reservoirs under different pressures and to compare the characteristics of episodic hydrocarbon accumulation and steady hydrocarbon accumulation under different charging pressures and at different charging direction.The results show that,regardless the direction of hydrocarbon expulsion from source rocks,the higher the pressure in the low-permeability lithology reservoirs is,the higher the hydrocarbon accumulation efficiency and the oil saturation are.