Diagenesis and diagenetic facies of Xujiahe Formation in the central west of Sichuan foreland basin

The structure in the Sichuan foreland basin is complicated,so the research on the differences of diagenesis and diagenetic facies in different tectonic zones is very significant to the reservoir prediction.Based on the analyses of sedimentary facies,cast thin slices,rock and mineral logging data,diagenesis of the sandstones in different tectonic zones of Xujiahe Formation have been researched systematically.The conclusion shows that in the thrusting nappe tectonic zone,there are mainly compaction and cataclasis.In the western depression,there are mainly compaction and pressolution,while in the ramp region and the uplift zone,the compaction is relatively weak and the rim agglutination of chlorite the compaction and denudation are relatively develop.The destructive diagenesis is mainly the compaction-pressure solution and cementation.The constructive diagenesis is mainly the rim agglutination of chlorite,denudation and cataclasis.Based on the research of diagenesis,the diagenetic facies is divided,and the diagenetic facies association of Xujiahe Formation sandstone is divided into three types,the diagenetic facies which is beneficial to the reservoir development are compaction-clastation-cementation and cementation-denudation types.