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成岩矿物的转化是致密砂岩储层物性变化的主要因素之一。为了探索二者之间的关系以及储层致密化成因,采用薄片观测、扫描电镜分析、阴极发光分析等手段,结合成岩演化过程中的矿物热力学特征和体积变化,探讨了苏里格气田西南部山1段、盒8段砂岩的矿物组成、孔隙特征、矿物转化机制及其对储层孔隙的影响。结果表明:1胶结物以黏土矿物、方解石为主,硅质少量;2绿泥石薄膜可包裹高岭石和石英加大边,偶见放射状绿泥石且孔隙较好;3黏土矿物晶间孔占孔隙比重较高,高岭石伊利石化后的晶间孔隙较发育,其次为溶蚀孔隙;4嵌晶状方解石充填剩余粒间孔隙,并交代石英加大边和伊利石,破坏储层物性。认为中成岩A期的钾长石溶蚀、蒙脱石伊利石化、高岭石伊利石化、黑云母水化都会使得矿物体积变小,属于增孔反应,在一定程度上改善储层孔隙;且胶结作用增加储层的抗压实能力,在一定程度上保护了原生孔隙;故在分析胶结作用对物性的影响时,不能简单地归结为破坏性成岩作用。
The conversion of diagenetic minerals is one of the main factors that change the physical properties of tight sandstone reservoirs. In order to explore the relationship between the two and the genesis of reservoir densification, combining with the thermodynamic characteristics and volume change of the minerals during diagenetic evolution, the observation of thin slices, scanning electron microscopy and cathodoluminescence, Mineral composition, pore characteristics, mineral transformation mechanism and its influence on reservoir porosity of sandstone in Block 1 and Block 8 of Shan. The results show that: (1) The cements are mainly composed of clay minerals and calcite with a small amount of siliceous. 2 Chlorite films can enclose kaolinite and quartz with larger edges and occasionally radial chlorite with better porosity. 3 Clay mineral intergranular pores Accounting for the higher specific gravity of the pores. Intergranular pores developed after the Kaolinite illite, followed by dissolved pores. 4 In-celled calcite filled the remaining intergranular pores and confined quartz to increase the edge and illite to destroy the reservoir physical properties. It is considered that the dissolution of potash feldspar, metamorphism of montmorillonite, illite of montmorillonite, hydration of biotite in meta-diagenesis stage A will make the mineral volume smaller, which belongs to the pore-increasing reaction and will improve the porosity of the reservoir to a certain extent; The effect of increasing the compressive compaction ability of reservoirs protects the primary pores to some extent. Therefore, when analyzing the influence of cementation on physical properties, it can not simply be attributed to destructive diagenesis.