元坝地区雷口坡组古岩溶储层特征

Characteristics of Leikoupo Triassic Paleokarst Reservoir in YuanBa Region

元坝地区雷口坡组为风化壳段,原始沉积的岩性以微晶、砂屑白云岩为主,夹薄层微晶灰岩和砂屑微晶灰岩。通过对研究区8口井岩芯观察、岩石薄片、阴极发光以及电子探针等测试手段,综合分析和研究风化壳岩溶储层特征。研究表明元坝地区雷口坡组在沉积后先后经历了沉积-埋藏、抬升暴露-风化剥蚀、再埋藏三个演化阶段,致使雷口坡组经受了多期次、多类型成岩作用的影响。通过孔隙度渗透率分析表明,元坝地区雷口坡组碳酸盐岩基质为低孔、低渗致密储层,不具储集性,油气主要储集在裂缝及未充填溶洞中。

Leikoupo Triassic Group in Yuanba Region is weathered crust.Original deposit lithology is mainly microcrystalline dolomite and doloarenite,micrite and psammitic micrite in laminated layer.By comprehensively analyzing the character of weathered crust karst reservoir bed in the area,it showed that Leikoupo Triassic Group in Yuanba Regoin went through three evolution stages after deposit：deposit-burying,uplift to exposure-weathering and reburying,which makes Leikoupo Triassic Group be affected by multiple times and types of diagenesis.Porosity permeability analysis indicated that carbonate rock matrix in Yuanba Regoin Leikoupo Triassic Group was low-porosity and hypotonic dense reservoir without reserved property, and the oil gas was mainly reserved in cracks and unfilled solution cavity.