胡尖山油田延长组长6段三角洲前缘致密砂岩储层特征及其主控因素

Characteristics and main controlling factors of tight sandstone reservoir in delta front facies in Chang 6 member of Yanchang Formation,Hujianshan oilfield

采用粒度分析、真空浸渍铸体薄片分析、扫描电镜检测、压汞测试、黏土矿物X射线衍射和常规物性分析等方法探究胡尖山油田延长组长6段三角洲前缘致密砂岩储层特征及其主控因素。结果表明:长6段储层致密砂岩主要为岩屑长石砂岩和长石岩屑砂岩,岩石成分成熟度和结构成熟度均较低;主要孔喉组合为残余粒间孔+长石溶孔+晶间孔的小孔-微细喉道组合,孔隙度和渗透率均值分别为10.70%,0.69×10^(-3)μm^(2);孔渗相关性较好,为低孔特低孔-特低渗超低渗小孔微细喉道型储层,渗透率主要由数量较少的微孔、中孔贡献,孔隙度主要由数量较多的微米孔贡献;强烈的压实、泥质、碳酸盐胶结作用是长6段储层致密的主要原因;水下分流河道等优势沉积相带和溶蚀作用是储层形成的主控因素。

The characteristics and main controlling factors of tight sandstone reservoirs of Chang 6 member,Yanchang Formation in Hujianshan Oilfield have been studied by particle size analysis,thin section,scan-ning electron microscopy detection,mercury intrusion testing,X-ray diffraction,and conventional physical property analysis.The results showed that the tight sandstone of Chang 6 member was mainly detritus feld-spar sandstone and feldspar detritus sandstone.The maturity of rock composition and structure was relatively low.The main pore throat assemblage included intergranular pore,feldspar dissolution pore and intercrystal-line pore.Average porosity and permeability were 10.70%and 0.69×10^(-3)μm^(2)respectively.The tight sand-stone of Chang 6 member in Hujianshan Oilfield was an ultra-low porosity,ultra-low permeability reservoir.There was a positive correlation between porosity and permeability.Permeability was mainly contributed by a small number of micropores and mesopores,while porosity was mainly contributed by a large number of mi-cron pores.The mechanism of reservoir densification included compaction and argillaceous,carbonate cemen-tation.The underwater distributary channel facies was the dominant sedimentary facies for the formation of high-quality reservoir.Dissolution was one of the main controlling factors for the formation of the reservoirs.