致密砂岩气储层微观孔隙及成岩作用特征—— 以川西新场地区须五段为例

为了更加准确地在川西新场地区三叠系须家河组五段中寻找有效储集体，利用岩石薄片、铸体薄 片、扫描电镜和微米 CT 扫描等资料，结合储层物性资料，对川西新场地区须家河组五段致密砂岩储层的 岩石学、微孔隙空间分布、成岩作用和储层物性等特征及储集空间类型进行了研究。 结果表明：须五段致 密砂岩储层岩石类型为岩屑砂岩和岩屑石英砂岩，储层超致密，储集空间为纳米级晶间孔、微米级溶蚀 孔及成因不同的微裂缝，其中晶间孔为储集空间的主体；综合岩心微米 CT 扫描结果发现，有机质丰度在 一定程度上控制了孔隙的发育和分布，孔隙度随有机质丰度的增大而增大；微孔隙的形态和分布影响了 储层的连通性，其集中连片分布优于分散孤立分布。 压实、交代和胶结等成岩作用是导致砂岩致密化的 重要因素，溶蚀作用对改善储层物性有一定的作用，但对砂岩孔隙度改变不大。

Characteristics of micropores and diagenesis of tight sandstone reservoirs: A case study from the fifth member of Xujiahe Formation in Xinchang area,western Sichuan Depression

In order to find out effective reservoirs in Xinchang area, western Sichuan Basin, the data of rock slices, casting slices, scanning electronic microscope and micro-CT scanning, as well as reservoir physical properties, were used to discuss the characteristics of petrologic features, reservoir spaces, pore types and diagenesis of tight sandstone reservoir of the fifth member of Xujiahe Formation. The results show that the tight sandstone is mainly of lithic sandstone and lithic quartz sandstone. The porosity of the reservoir is low and the reservoir is super tight. Reservoir space consists of nano intergranular pores, micron dissolved pores and micro cracks of different genesis, among which the intergranular pores are the main reservoir space. According to the micro-CT scanning results, the abundance of organic matter in the sandstone controls the development and distribution of pores, and the porosity increases with the raise of the abundance of organic matter. The shape and distribution of micro pores affect reservoir connectivity, andthe connectivity rate of concentrated micro pores is superior to scattered micro pores. Compaction, replacement and cementation are the major causes of density of reservoir. Dissolution has a certain positive impact on improving the physical properties of reservoir, but makes little change of porosity.