优质白云岩储层形成的重要机制——差异溶蚀作用

Most Important Mechanism of Carbonate Reservoir:Differential Corrosion

碳酸盐岩的溶蚀是指在水-岩作用过程中由于Ca^(2+)、Mg^(2+)流失所导致的岩石的质量亏损。温度、压力、水溶液介质(酸碱度)是影响碳酸盐岩溶蚀的主要因素。在同样条件下,碳酸盐岩因为岩石成分(灰岩和白云岩的相对含量)和结构的差异也会表现出不同的溶蚀速率。碳酸盐岩由于岩石成分和岩石结构的不同所导致的溶蚀速率的差别定义为"差异溶蚀"。结合川东北地区飞仙关组储层的研究,指出岩石结构、成分的非均质性导致的差异性或选择性溶蚀是该区优质储层形成主要原因,灰质云岩是优质储层形成的重要物质基础。

The erosion of carbonate rock refers to its quality decrease due to Ca2＋,Mg2＋ loss in the process of the water-rock interaction. The major effect factors of the carbonate rock corrosion are temperature,pressure,water solution（ pH）. Under the same condition,carbonate rock composition（ the relative content of limestone and dolomite） and structural differences will show different corrosion rate,which is named ＂differential corrosion＂. Based on the reservoir of Feixianguan Formation in Northeast Sichuan area,it is concluded that the heterogeneity of rock components and rock structure leading to differential corrosion or selective corrosion is the most important mechanism of high-quality dolomite reservoir formation. Development of calcite dolomite is the most important material foundation of high-quality dolomite reservoirs.