鄂尔多斯盆地子洲-清涧地区上古生界山32段储层砂岩成岩作用

鄂尔多斯盆地子洲-清涧地区上古生界山 32段砂岩储层以石英砂岩为主,其次为岩屑质石英砂岩和岩屑砂岩.目前储层正处于晚成岩阶段B期,成岩作用类型包括压实作用、胶结作用、交代作用和溶蚀作用,机械压实作用、压溶作用和自生黏土矿物的胶结作用是低孔低渗储层形成的主要原因,成岩晚期的溶蚀作用大大改善了砂岩储层的储集空间.根据成岩作用的特点,将研究区山 32段划分出5个成岩相:压实压溶相、弱压实-硅质胶结相、弱压实-自生黏土矿物胶结相、弱压实-碳酸盐胶结相、弱压实-溶蚀相.压实压溶相储层物性最差;弱压实-硅质胶结相、弱压实-自生黏土矿物胶结相和弱压实-碳酸盐胶结相储层的孔隙度、渗透率总体也很低;弱压实-溶蚀相储层的储集空间最发育、连通性最好,孔隙类型以粒间孔、粒间溶孔、粒内溶孔为主.

Diagenesis of Sandstones Reservoir in the Upper Palaeozoic Shan 32 of Zizhou-Qingjian Area,Ordos Basin

The standstone reservoir in the Upper Paleozoic Shan^32 of Zizhou-Qingjian area is domoninated first by quartz sandstone and next by lithic sandstone and lithoclastic quartz sandstone. The reservoir , now in the late diagenetic phase B , has already experienced compaction, cementation, metasomatic alteration, recrystallization and corrosion. The mechanical compaction in the early diagenetic phase and the ferruginous carbonate cementation in the late diagenetic phase are mainly responsible for the poor poroperm characteristics. Among the five diagenetic facies zones in the study area, the reservoir physical property of compaction and pressolution diagenetic facies is worst and that of weak compaction-siliceous cementation, weak compaction-hydrosialite cementation and weak compaction-carbonate cementation diagenetic facies is worse. However, the standstone reservoir of corrosion cementation has the best physical property, owning intergranular pores, intercrystal pores and all kinds of emposieu.