Reservoir characteristics and controlling factors in the 4th member of the Xujiahe Formation in the Xinchang structural zone, western Sichuan

With the aid of core observation, thin section examination, CL and SEM, the present paper deals with petrology, reservoir space types and physical properties, and the effects of sedimentary environments, diagenesis, tectonism on reservoir potential of the reservoir rocks in the Xujiahe Formation in the Xinchang structural zone, western Sichuan. The diagenetic processes of the reservoir rocks in the study area include compaction, cementation, dissolution and replacement. The favourable reservoir rocks occur in the medium-to fine-grainded sandstones with moderate to good sorting and low matrix contents. The reservoir space types contain intergranular and intragranular solution openings. The distributary channels and channel mouth bars are believed to be favourable sites, and secondary porosity and fissures may improve the reservoir quality of the reservoir rocks in the study area.