砂岩中碱性溶蚀研究进展

火山物质和长石碱性溶蚀形成的绿泥石、浊沸石、钠长石、伊利石等碱性自生矿物，是砂岩储层研究的重点，而碱性溶蚀本身却常被忽略。通过对碱性溶蚀机理、控制因素及成岩特征的分析，发现砂岩中发育石英颗粒碱性溶蚀、火山物质水解溶蚀、蒙脱石伊利石化导致的钾长石溶蚀、高岭石伊利石化导致的钾长石溶蚀和斜长石钠长石化5种碱性溶蚀作用，它们常与酸性溶蚀先后叠加发生，不易直接确定碱性溶蚀的类型和规模，常被忽略或误判为酸性溶蚀。依据碱性溶蚀与其伴生胶结物的成因关系，分析了部分含油气储层的碱性溶蚀类型及溶蚀规模，我国含油气盆地碱性溶蚀十分普遍，前4种碱性溶蚀形成的次生孔隙分别可达2%~7%, 5%~10%, 1.32%, 1.63%。 

Advance in alkaline dissolution of sandstone

Alkaline authigenic minerals such as chlorite, laumontite, albite, and illite formed by alkaline dissolution of volcanic materials and feldspar are the focus of sandstone reservoir research, but alkaline dissolution itself is often ignored. Through analysis of the alkaline dissolution mechanism, controlling factors and diagenetic characteristics, it is found that alkaline dissolution includes five types: alkaline dissolution of quartz grains, hydrolysis and dissolution of volcanic materials, K-feldspar dissolution caused by illitization of montmorillonite, K-feldspar dissolution caused by illitization of kaolinite, and albitization of plagioclase. As alkaline dissolution is often superimposed with acid dissolution, it is difficult to directly determine the type and scale of alkaline dissolution and is often ignored or misjudged as acid dissolution. Based on the genetic relationship between alkaline dissolution and its associated cements, the type and scale of alkaline dissolution of some sandstone reservoirs are analyzed. Alkaline dissolution is very common in the petroliferous basin of China, and the secondary pores formed by the first four kinds of alkaline dissolution can reach 2%-7%, 5%-10%, 1.32% and 1.63%, respectively.