川西前陆盆地上三叠统须家河组储层主要为一套辫状河三角洲相砂岩，储集岩主要为岩屑石英砂岩、长石岩屑石英砂岩和岩屑长石石英砂岩，经历了压实压溶、胶结、交代、溶蚀和破裂等多种成岩作用，其中压实压溶、胶结作用起主要的破坏作用，溶蚀和破裂作用起主要的建设性作用。目前该区砂岩已达到晚成岩阶段B期，砂岩储层经成岩演化其原生孔隙大部分被破坏，主要以次生孔隙为主，而孔隙演化经历了原生孔隙的破坏、次生孔隙的形成和次生孔隙的破坏3个阶段。

Upper Triassic Xujiahe Formation sandstone is a set of braided river deltaic sediments, which is comprised of lithic quartz sandstone, feldspar lithic quartz sa

ndstone and lithic feldspar quartz sandstone. The sandstone went through compaction, pressolution, cementation, metasomasis, corrosion and fracturing during the diagenesis, and now it is in the late diagenesis stage B. Most primary pores were destructed after the diagenetic evolution, and the pores are mainly secondary, indicating that the diagenesis is the key factor of controlling the physical properties in this area. Porosity evolution in the rock has experienced the destruction of primary pores and the construction and destruction of secondary pores. Compaction, pressolution and cemetation contribute to destruction, while corrosion and fracturing to construction.