雪峰山西侧地区下古生界海相白云岩储层的成岩作用

摘要

分析雪峰山西侧震旦系灯影组、寒武系武陵统—芙蓉统海相白云岩的区域分布特征和储层岩石学特征,并结合普通薄片、铸体薄片、碳氧同位素、常量元素、电子探针等资料,定量化研究对储层发育起建设性作用的成岩类型,探讨其纵横向差异.结果表明,研究区白云岩的分布特征明显受相带变化的影响和控制；震旦系灯影组主要为晶粒白云岩、残余颗粒白云岩和藻白云岩,武陵统—芙蓉统则以灰质白云岩、晶粒白云岩和残余颗粒白云岩为主.灯影组与武陵统—芙蓉统白云岩成岩期主要经历了压实压溶、胶结和矿物充填、重结晶、白云岩化、硅化、溶蚀、破裂等作用,其中对形成有利储集空间起积极作用的主要有白云岩化、溶蚀、破裂等.区域对比表明,武陵统—芙蓉统和灯影组白云岩储层在纵向上和平面上存在差异,在区域展布上存在不均一性.研究结果为下一步区块优选提供了一定的依据.%Based on an analysis and discussion on the diagenesis of Lower Paleozoic marine dolomite reservoirs in the study area, the authors acquired a better understanding of the characteristics of these reservoirs. On the basis of oil and gas geological data obtained through the analysis of the Sinian Dengying Formation and the regional distribution characteristics of the Cambrian Wuling - Furon-gian marine dolomite reservoirs, in combination with ordinary thin section, casting thin sections, carbon and oxygen isotopes, major elements, electron microprobe analyses and other data, the authors conducted comprehensive quantitative researches on the types of diage-netic types that played a constructive role in reservoir development, and explored their differences in vertical and horizontal directions. The results show that the distribution characteristics of the dolomite in the study area are significantly affected and controlled by facies change; Sinian Dengying Formation consists mainly grained dolomite, residual particles of dolomite and algal dolomite, whereas Wuling -Furongian System comprises chiefly calcite dolomite, grained dolomite and residual grained dolomite. Dolomite of Dengying Formation and Wuling-Furongian System experienced such diagenetic actions as compaction and dissolution of cement and mineral filling, re-crystallization, dolomitization, silicification, dissolution and rupturing, which all played positive roles in the formation of favorable reservoir space, with dolomitization, dissolution and rupturing being most important- Regional correlation shows that dolomite reservoirs in Wuling-Furongian System and in Dengying Formation are somewhat different in vertical and horizontal directions and assume heterogeneity in regional distribution. The results obtained by the authors provide the basis for further regional block optimization.