RESERVOIR DIAGENESIS OF SHIHEZI 8 MEMBER, YANCHANG OIL AND GAS REGION IN ORDOS BASIN

In this paper, the petrological characteristics, diagnesis type and diagenetic-stage classification, and their impact on pore are studied for Shihezi 8 Member of Yanchang oil and gas region based on some data of thin section, casting thin section, SEM and X-refraction. Results show that: (1) this reservoir is mainly composed of lithic quartz sandstone with a higher composition maturity and a lower texture maturity; (2) diagenesis mainly include compaction, cementation and dissolution; (3) it is basically in late diagenetic stage B, partly in late diagenetic stage C; (4) the compaction from early diagenetic stage A to late diagenetic stage B and the metaomatic alteration in late diagenetic stage A are the two important factors which can make physical property poorer; (5) the packing and cementation are other factors; and (6) the cementation and dissolution around chlorite rim are the other factors which can make physical property better.