鄂尔多斯盆地华庆地区延长组长6储层成岩相及微观孔隙结构

摘要

鄂尔多斯盆地华庆地区延长组长6储层物性差、非均质性强.利用铸体薄片、扫描电镜、X衍射、物性、高压压汞等分析测试手段,深入分析了超低渗储层成岩作用、成岩相及其微观孔隙结构特征.结果表明:发育的优势储集成岩相主要有水云母胶结-残余粒间孔+长石溶蚀相、长石溶蚀+水云母胶结-残余粒间孔相、长石溶蚀+绿泥石膜胶结-残余粒间孔相等.不同类型成岩相的微观孔隙结构特征不同,孔喉比和配位数与最大进汞饱和度和退汞效率有很好的对应关系,即孔喉比越小,配位数越大,则最大进汞饱和度和退汞效率越大,如水云母胶结-残余粒间孔+长石溶孔相；反之,孔喉比越大,配位数越小,最大进汞饱和度和退汞效率越小,如长石溶孔+绿泥石膜胶结-残余粒间孔相.%The physical property of Chang 6 reservoir was poor with strong heterogeneity in Yanchang Formation, Huaqing area, Ordos Basin. In this paper, casting thin sections, SEM, X-ray diffraction, physical properties , high pressure mercury injection and other analytical testing methods were used to analyze the diagenesis, diagenetic facies and micro-pore structure of the low permeability reservoir deeply. The results showed that; main reservior diagenetic facies were the hydromica cementation-integranular pore and feldspar dissolution diagenetic facies, feldspar dissolution and hydromica cementation-integranular pore facies, feldspar dissolution and chlorite cementation-integranular pore facies. The features of microscopic pore structures of various types of diagenetic phases were different. And the pore-throat ratio and coordination number with mercury injection saturation and mercury withdrawal efficiency had a good correspondence. That is, the smaller the pore-throat ratio was, the greater the coordination number was, and the greater the mercury injection saturation and mercury withdrawal efficiency were, such as the hydromica cementation-integranular pore and feldspar dissolution diage-netic facies; otherwise, the greater the pore-throat ratio was, the smaller the coordination number was, and the smaller the mercury injection saturation and mercury withdrawal efficiency were, such as the feldspar dissolution and chlorite cementation-integranular pore facies.