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

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。

Diagenetic Facies and Micro-pore Structure of Chang 6 Reservoir in Yanchang Formation, Huaqing Area, Ordos Basin

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 diagenetic 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.