松辽盆地南部红岗阶地和华字井阶地含片钠铝石砂岩中的黏土矿物特征

Characteristic of clay in dawsonite-bearing sandstones in Honggang terraces and Huazijing terraces of Songliao basin

松辽盆地南部中央坳陷红岗阶地和华字井阶地含片钠铝石砂岩中黏土矿物主要由伊/蒙混层、伊利石和高岭石组成。采用比较岩石学和数值模拟方法,比较红岗阶地青山口组和华字井阶地泉头组含片钠铝石砂岩与对照组砂岩的岩石学特征。研究结果表明:含片钠铝石砂岩中绿泥石缺失,高岭石和伊利石质量分数显著增加;绿泥石溶解和高岭石沉淀作用发生在深大断裂附近,深大断裂是幔源CO2运移的主要通道;CO2充注引起注入点附近砂岩储层中绿泥石溶解和自生高岭石沉淀以及长石的高岭石化;长石等可溶性矿物的溶解,为伊/蒙混层向伊利石转化提供必需的K+,促进伊/蒙混层向伊利石的转化。

Clay minerals consist of illite/smectite, illite and kaolinite in dawsonite-bearing sandstones in Honggang terrace and Huazijing terrace in south of Songliao Basin. The petrology of dawsonite-bearing sandstone and control group from Honggang terrace and Huazijing terrace was investigated by the method of comparative petrology and numerical simulation. The results show that chlorite in dawsonite bearing sandstone is lack, and the mass fraction of kaolinite and illite significantly increases. Dissolution of chlorite and precipition of kaolinite occur in deep fault, which is the main channel of mantel-genetic CO2 influx. Chlorite dissolution, authigenic kaolinite precipition and kaolinization of feldspar are impacted by CO2 injection. CO2 inject leads to dissolubility feldspar dissolution. K-feldspar dissolution mainly provides K＋, which is necessary for illitization of smectite.