雪峰山西侧重点白云岩储层成岩、储集特征及质量影响因素

Lithogenic and accumulation characteristics as well as quality affecting factors of Middle-Upper Cambrian strata and Sinian Denying Formation dolomite reservoirs on the western side of the Xuefeng Mountain

雪峰山西侧地区下古生界中—上寒武统和震旦系灯影组白云岩是潜在的重要油气储集层。作为主要目的层段,本区的白云岩类型主要包括结晶白云岩、残余颗粒白云岩、灰质白云岩和藻白云岩四大类。白云岩储层总体上均属于低—特低孔、低—特低渗储层。影响储层发育的成岩事件包括重结晶作用、白云岩化作用、溶蚀作用、破裂作用等。研究表明,白云岩结晶程度可以影响其初始孔隙的发育程度,具粉晶—细晶结晶程度的白云岩具有最好的孔渗性。白云岩化作用的强弱对储层物性具有较为直接的影响。最佳白云岩储层中主要储集空间包括晶间孔隙(包括剩余晶间孔和晶间溶蚀孔)、次生溶孔、洞和裂缝。总体上,较强的白云岩化作用、一定程度的重结晶、较发育的微裂缝、较好的区域渗透性、晚期压溶缝合线发育和晚期较大构造缝不发育等因素有利于白云岩储层的发育。

Middle-Upper Cambrian strata and Sinian Denying Formation dolostones on the western side of the Xuefeng Mountain constitute important potential reservoirs. Reservoir characteristics are described based on petrologic, mineralogical, and petrophysical analysis. The lithfacies include mainly crystalline dolostones, remnant grained dolostones, calcareous dolostones, and algal dolostones. Depositional facies and various types of diagenetic alterations have caused considerable deterioration and heterogeneity in the target reservoirs. The carbonates have been subjected to extensive diagenetic actions such as recrystallization, dolomitization, dissolution, cal- cite cementation, and fracturing. Fine crystalline dolomites have higher porosity than microdolomites and coarse crystalline dolomites. There is a clear relationship between porosity and degree of dolomitization in the target strata, suggesting that dolomitization enhances porosity. Porosity in the target layers includes intercrystalline （remnant and sohition-enlarged）, secondary, vuggy, and fracture types. In general, dolomitization, recrystallization, fracturing, regional open environment, and late stylolites caused by pressure dissolution are beneficial to the development of high-quality reservoirs.