Diagenesis factor that effect the reservoir properties and gas accumulation in the 4th member of Xujiahe formation, Western Sichuan Basin, China

摘要

Reservoir properties of the fourth member of the Xujiahe Formation in the Western Sichuan Depression are quite poor (average porosity =5.9%, average permeability =1.41 mD). These properties were influenced by several diagenetic processes, especially compaction and carbonate cementation. Due to a combination of compaction of ductile fragments and carbonate cementation, sand/mud interfaces of the thick sandstone layer were tightly cemented, pore space also reduced sharply in positions where rich in ductile grains. Thus, space leaving for hydrocarbon is limited, except where both the detrital ductile grain content and carbonate cement content are low.