黔北金沙岩孔地区灯影组储层特征与成岩作用

Reservoir characteristics and diagenesis of the Sinian Dengying Formation in the Yankong area,northern Guizhou Province,China

研究黔北金沙县岩孔地区震旦系灯影组白云岩储层特征、多种不同类型的成岩作用以及成岩演化序列。在野外实测剖面的基础上,开展岩石薄片显微鉴定、储集岩物性分析、阴极发光以及原位激光微区痕量元素分析研究。结果表明主要储集岩类型为藻砂屑白云岩、葡萄花边状白云岩、藻粘结白云岩、残余藻砂屑粉晶白云岩和残余砂屑粉晶白云岩;储集空间类型以晶间孔、粒内溶孔、藻格架(溶)孔为主;储层成岩作用具有多类型、多期次改造和叠加的特征,主要的成岩作用有压实压溶作用、胶结充填作用、白云石化作用、溶蚀作用、硅质交代作用和重结晶作用。根据成岩作用的先后顺序,结合成岩环境演化特征,确定岩孔地区灯影组储层的成岩过程经历了(准)同生成岩、早成岩、表生成岩、中-晚成岩4个阶段。

The measured cross section in the Yankong area of northern Guizhou Province are studied by means of microscopic identification of thin sections,analysis of reservoir rock physical properties,cathodoluminescence and in-situ laser micro-area trace element analysis,so as to unravel the characteristics of diagenesis and diagenetic sequence of Sinian Dengying Formation dolomite reservoir.It shows that the main reservoir rock types of the Dengying Formation in the Yankong area are algal dolarenite,grape lace-like dolomite,algal bound dolomite,residual algal arenaceous powder crystal dolomite and residual arenaceous powder crystal dolomite.Intergranular pores,intragranular dissolution pores and algae-frame(dissolution)pores constitute the main storage space types.Reservoir diagenesis of the Dengying Formation is characterized by multiple types,multiple stage transformation and superposition.In fact,the main diagenetic types include compaction,dissolution,cemented filling,dolomitization,dissolution,silica metasomatism and recrystallization.According to the diagenetic sequences and the characteristics of diagenetic environment evolution,the Sinian Dengying Formation reservoir in the Yankong area experienced 4 diagenetic stages.They are(quasi)diagenetic stage,early diagenetic stage,supergene diagenetic stage and middle-late diagenetic stage.