川西北地区上三叠统油气勘探方向

文章对川西北地区上三叠统油气成藏条件进行了系统分析，认为该地区须二、四段储层在晚成岩A期和早成岩期致密化。须四段地层压力高于须二段，储层间存在强烈的分隔性和流体的封闭环境。须一段烃源岩在晚侏罗世-白垩纪初进入成烃高峰期。强生烃区分布在江油-安县-绵阳地区。中坝须二段、魏城须四段气藏形成于印支期和燕山中晚幕，储层致密化和非均质性使高压区油气运聚规模有限。生烃量大、次生孔隙和微裂缝系统发育带是获得高产气井的关键因素。构造的早期形成和继承性隆升，是高丰度气藏形成的有利条件。高孔隙度发育区梓潼凹陷西斜坡、魏城-文兴场为须二、四段有利勘探区。

1.Northwest Sichuan Gas Field of Southwest Branch, PetroChina; 2.Southwest Petroleum Institute

Oil-gas reservoiring conditions of Upper Triassic Series in Northwest Sichuan area are systematically analyzed to determine the new exploratory targets in the area. It is considered that the reservoirs of Xu 2 and Xu 4 members are at the stage of late diagenetic A and early diagenetic stage of tightening: The stratum pressure of Xu 4 member is higher than that of Xu 2 member; intensive separation and fluid closed environment exist among the reservoirs. The source rock of Xu 1 member got into the peak stage of hydrocarbon-forming in late Jurassic Epoch-initial Cretaceous and the strong hydrocarbon-generating districts distributed in Jiangyou-Anxian-Mianyang areas. The reservoirs of Zhongba Xu 2 member and Weicheng Xu 4 member formed at the middle-late stage of Indo-Chinese epoch and Himalayan epoch. Reservoir's tightening and heterogeneity made the oil-gas migration scale be confined. The belts with a great quantity of hydrocarbon-generating, developed secondary pores and micro-fractures are the key territory of obtaining high-yield wells. The structural early formation and sequential uplift are the favorable conditions of forming high abundance gas reservoir. The developed zones with high porosity, such as the west slope of Zitong Sag, Weicheng-Wenxingchang are the favorable exploration areas of Xu 2 and Xu 4 members.