黄河口凹陷BZ34区古近系沙一二段储集层成岩相与有利储层预测

Reservoir Diagenetic Facies and Favorable Reservoir Prediction of the Member 1 and 2 of Palaeogene Shahejie Formation in BZ34 Area of Huanghekou Depression

通过铸体薄片、扫描电镜、电子背散射、阴极发光等技术手段结合物性资料以及沉积(微)相划分,对研究区沙一二段储集层成岩作用类型及点(薄片)、线(单井)、面(平面展布)成岩相分布及有利储层分布进行了研究。结果表明:研究区沙一二段受同沉积火成岩喷发和水解的影响,广泛发育栉壳状白云石、钾长石钠长石化、石英溶蚀等碱性条件下发生的成岩作用,同时层状分布的火山岩对于下覆地层起到了保护作用,减弱了下覆地层的压实作用;此外,受后期酸性流体的影响,研究区也发育诸如长石、岩屑溶蚀等酸性条件下发生的成岩作用,沙一二段储层发育溶蚀孔,占比达到56.7%(均值)。采用"(微相)砂体部位+主体成岩现象+孔隙类型"的复合命名方式,对薄片、单井及平面区域进行了成岩相的命名和划分,共划分为三类:水下分流水道砂体侧翼细粉砂岩-菱铁矿胶结-低孔成岩相、三角洲前缘-中细砂岩-欠压实-白云石包壳-溶孔相、火山熔岩远端凝灰质中细砂岩-凝灰质胶结-致密相。欠压实-白云石包壳-溶孔相在测井响应上具有DT低、RD与RS间隔幅度较大、CNCF与RHOZ较为接近或交叉的特点;菱铁矿胶结-低孔成岩相具有DT高、RD与RS较为接近、CNCF与RHOZ间隔幅度较大的特点,测井解释的油层、油水同层与欠压实-白云石包壳-溶孔相具有较好的匹配关系。三角洲前缘-中细砂-欠压实-白云石包壳-溶孔相为有利储层发育区带。

To study the diagenesis,diagenetic facies（ point,line,plane） and favorable reservoirs of of Es1- 2,casting thin sections,scanning electron microscope（ SEM）,electron backscatter differaction（ EBSD）,cathode luminescence（ CL）,physical properties data and sedimentary microfacies analysis have been applied to the sampled drilling wells. The result indicates that： influenced by synsedimentary volcanic eruption and hydrolysis,diagenesis in alkaline condition took place in Es1- 2reservoir,forming ctenoid dolomite,potassium feldspar albitization and quartz dissolution. Meanwhile the layered igneous rock protected the underlying stratum by weakening the compaction. Besides,diagenesis in acid condition followed,such as dissolving feldspar and debris. Dissolved pore accounts for 56. 7% percentage（ average value） in Es1- 2reservoir. Adopting composite naming way as the diagenetic facies of casting thin section,single well and planar region are named following the ＂（ microfa-cies） sandstone position ＋ main diagenesis phenomenon ＋ pore types＂,and classified into three types： the underwater distributary channel sand body flank-fine-silt sand-siderite cementation-low porosity facies,the delta front-medium-fine sand-undercompaction-dolomite involucrum-dissolved pore facies and the distal volcanic lavatufaceous medium-fine sand-tufaceous cementation-tight facies. The identification of oil reservoir and oil-water reservoir by well logging interpretation matched the undercompaction-dolomite involucrum-dissolved pore facies.In this research,the most prospected reservoir favors the delta front-medium-fine sand-undercompaction-dolomite involucrum-dissolved pore facies.