延安南部曹凡峪油区长6油层组成岩作用研究

曹凡峪油区延长组长6油层组是曹凡峪地区主要的产油层,通过砂岩薄片、铸体薄片、扫描电镜等分析资料,对曹凡峪地区长6砂岩储层的岩石学特征、成岩作用类型、成岩阶段划分和孔隙演化影响因素进行分析。研究结果表明:长6储层发育细粒长石砂岩,主要成岩作用有压实作用、碳酸盐胶结作用、硅质胶结作用和溶解作用,曹凡峪长6成岩阶段为晚成岩A期早期。将研究区长6储层砂岩划分为5种成岩相,分别为绿泥石膜-方解石胶结-溶蚀孔隙相、方解石胶结-残余孔隙相、硅质胶结-粒间孔隙相、绿泥石胶结-残余粒间孔隙相、绿泥石膜胶结-溶蚀孔隙相。储层孔隙演化的影响因素主要是沉积环境和成岩作用,其中水下分流河道和原生残余粒间孔是研究区最好的储集场所和空间。有利成岩相和沉积环境的结合形成了研究区物性相对较好,产量较高的储层区带,也是下一步勘探的重点。

Chang 6 sandstone diagenesis of Caofanyu in the south of Yanan

Chang 6 reservoir of Upper Triassic is a major oil producing zone in Caofanyu area, Ordos Ba- sin. The article based on the analysis of cast slice, SEM and other test, the characteristics of petrology, type of diagenesis, division of diagenetie stage and the factors of pore evolution are analyzed. The results show that the lithology is mainly fine-frained feldspathic litharenite, types of diagenesis are compaction, carbonate cementation, silicious cementation and dissolution. The diagenetic stage in Chang - 6 Forma- tion is early phase A period mesogenetic stage. Chang 6 sandstones in Caofanyu area are divided into five diagenetic facies, and these are chlorite coating-calcite cementation denudation pore facies, calcite ce- mentation-residual pore facies, siliceous cementation-intergranular pore facies, chlorite coating-residual intergranular pore facies and chlorite coating-Denudation pore facies . The influence factors of reservoir pores mainly include sedimentary facies and diagenesis. Underwater distributary channel and residual intergranular pores are the best reservoir spaces. The relatively high porosity and high permeability reser- voirs which are formed by favorable diagenetic and sedimentary environment facies is the important target for the next step prospecting.