Reservoir space and diagenesis evolution in the Chang 4+5 reservoir of Jing'an oilfield

The Chang 4+5 reservoir of the Jing'an oilfield is studied for petrology,reservoir space,pore throat,diagenesis and evolution characteristics by using casting thin section,scanning electron microscope,cathodoluminescence and X-ray diffraction analysis.The results show that the sandstone reservoir in the study area is characterized by low compositional maturity,medium textural maturity,intergranular pores and feldspathic dissolved pores,fine pore throat,poor sorting,high displacement pressure and median pressure,and low mercury withdrawal efficiency.Clay filling is often seen in reservoir pores such as authigenic quartz,augmented feldspar,and chlorite,etc.Pore-throat combination pattern in the study area is featured by tiny pore-fine throat.The diagenesis of reservoir rock involves compaction,cementation,metasomatism and denudation.Complex diagenetic evolution process had exerted significant influence on petrophysical properties.