辽东湾地区古近系砂岩成岩作用与孔隙演化

Diagenesis and porosity evolution of the paleogene sandstone reservoirs in Liaodongwan Area

辽东湾地区古近系砂岩储层为近岸水下扇、(扇)三角洲和浊积扇的长石砂岩和岩屑长石砂岩.岩石主要经历了压实、胶结、溶蚀和交代等成岩作用,溶蚀作用主要为有机质热成熟演化形成的有机酸和黏土矿物转化脱出的水对易溶物质的溶蚀.成岩阶段可分为早成岩A期,早成岩B期和中成岩A期.中成岩A期又分为中成岩A1亚期和A2亚期,中成岩A1亚期是溶蚀作用发生的主要时期.孔隙类型包括原生孔隙和次生孔隙,次生孔隙主要由碳酸盐胶结物、长石及部分岩屑溶蚀形成.次生孔隙在现今埋深2000～2500m的砂岩中最发育,其形成主要受成岩演化阶段控制.

The Paleogene sandstone reservoir in Liaoodngwan area is arkose and lithic arkose.The sandstones undergo numerous diagenetic processes,such as compaction,cementation,dissolution and metasomasis.The dissolution is mainly some matter being dissolved by the organic acids formed in the thermal evolution of organic matter and the water dehydrated in the transformation of the clay mineral.The diagenesis stage can be divided into early diagenesis 'A',early diagenesis 'B' and middle diagenesis 'A',and the middle diagenisis 'A' can further be divided into middle diagenesis 'A1' and middle diagenesis 'A2'.The dissolution took places mainly in the middle diagenesis 'A1'.The pores consist of primary pores and secondary ones,and the secondary pores are mainly generated from the dissolution of carbonate cement,feldspar and cuttings.The secondary pores mostly developed in the sandstones buried in 2000-2500m currently,and its distribution is controlled mainly by diagenesis.