成岩圈闭对气藏的影响--以英吉苏凹陷英南2气藏为例

INFLUENCES OF DIAGENETIC TRAP ON GAS POOLING:A CASE STUDY OF YINGNAN-2 GAS RESERVOIR IN YINGJISU SAG

为了研究成岩圈闭对气藏形成的影响,以塔里木盆地英吉苏凹陷英南2气藏为例,综合利用物性、铸体薄片、扫描电镜和黏土矿物X光衍射等资料,研究了其侏罗系—志留系砂岩的成岩阶段、成岩作用类型、成岩相特征及成岩圈闭的形成。结果表明:不稳定碎屑溶蚀相控制的砂岩可以成为良好的储层,而混层黏土胶结相和泥质杂基压实充填相控制的砂岩则可以成为优质盖层,不同成岩相控制的砂岩纵向上组合形成了较为特殊的成岩圈闭,从而为气藏的形成提供了条件。该项研究提出了一种新的气藏圈闭形成模式,为研究气藏形成机理提供了新思路。

The gas reservoir Yingnan-2 in Yingjisu sag,the Tarim basin,is taken as an example for studying the influences of diagenetic traps on gas pooling.The physical property,cast thin section,scanning electronic microscope,clay mineral X-ray diffraction data are integrated to study the diagenetic stage,diagenetic types,features of diagenetic facies and the formation of diagenetic trap in the Jurassic-Silurian in the study area.The results reveal that the sandstone under the control of unsteady clastic dissolution facies may be good reservoirs,while that under the control of mixed layer clay cement facies and muddy mixed-matrix compaction-filling facies can act as good seals.The vertical combination of sandstones under the control of different diagenetic facies forms relatively special diagenetic traps which provide the conditions for hydrocarbon pooling.This paper presents a new trapping model of gas and provides a new concept for studying the mechanism of gas pooling.