准噶尔盆地西缘二叠-三叠系扇控成岩储集相成因机理

对准噶尔盆地西缘前陆冲断背景下形成的扇控沉积储层特征的研究,发现沉积、构造、流体和热演化4种机制是主要的成岩成孔作用,各自的成因机理不同,据此提出了4种成岩储集相成因机制和相应的发育模式。指出二叠-三叠系储层孔隙空间主要以溶孔为主,发育粘土收缩孔缝、粒内缝、颗粒溶蚀、沸石溶蚀、构造缝及气孔等多种成岩储集相。不同成岩成孔机制相互配合是形成该区有利成岩储集相的条件,预测断裂发育区油气勘探有利埋深度可达7000m,非断裂发育区油气勘探有利埋藏深度可达4500m,改变了原来对该地区有效储集层埋藏下限深度为3500m的观点。这对我国类似地区的有利成岩储集相预测具有理论参考价值,对油气勘探具有指导作用。

GENETIC MECHANISM OF DIAGENESIS-RESERVOIR FACIES OF THE FAN-CONTROLLED PERMO-TRIASSIC IN THE WESTERN MARGINAL AREA, JUNGGAR BASIN

A study on reservoir characteristics of the fan-controlled sediments in the tectonic setting of foreland thrusting in the western marginal area of the Junggar Basin indicated that the sedimentation,structure,fluid and thermal evolution might be four main controlling factors on genetic mechanisms of diagenesis and porotization,and each of them having varied mechanism.Based on the view point,the paper put forward four genetic mechanisms of diagenesis-reservoir facies and the corresponding growth patterns.In the Permo-Triassic in western marginal area of the Junggar Basin,the main pore space of reservoir was dissolved pores,with multiple diagenesis-reservoir facies developed,such as the shrunk holes and fissures of clay,the intra-grain fissures,the holes of dissolved grain and zeolite,the structural fissures,the vesicles and others.The interaction and combination of different diagenesis-porotization mechanisms might create an interesting condition for favorable diagenesis-reservoir facies in the area.It was expected that the depth of exploration might be 7 000 m in faulted zone and 4 500 m in non-faulted region respectively,which changed the former view of the lowest limit of effective reservoir being depth of 3 500 m.The successful experience in western Junggar must be a theoretical reference for the predict of favorable diagenesis-reservoir facies in the similar area of China and a useful guidance for the oil-gas exploration.