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通过对永安镇油田沙四段砂岩储层中6口井的薄片、电镜及X衍射分析,研究了该储层中自生粘土矿物的分布产状、构成因素和成岩特征。根据自生粘土矿物在孔隙壁和孔隙喉道中的位置及分布状态,可将其分为孔隙分散粘土、孔隙衬边粘土和孔隙桥接粘土3种。研究区内自生粘土矿物的成岩相可划分为早成岩A期、B期及晚成岩A期和B+C期。在4个不同的成岩时期,自生粘土矿物的组合形式也不同。其垂向演化可以划分为3个带,即浆脱石带、I/S混层带和伊利石带。不同的转化带,自生粘土矿物的分布产状也不同,其中孔隙桥接粘土对孔隙度和渗透率影响最大。自生粘土矿物的存在,既可导致微粒的迁移,吸收或释放某些阳离子形成不溶沉淀物,堵塞孔隙喉道,改变储层孔隙结构,又可影响测井结果。为了减少自生粘土矿物对储层特性和测井结果的影响,文中提出了一些保护油层的措施。
By analyzing the thin-section, electron microscopy and X-ray diffraction of six wells in the sandstones of the fourth member of Yong’an Town in Oilfield, the distribution and composition of authigenic clay minerals and their diagenetic characteristics were studied. According to the location and distribution of authigenic clay minerals in pore walls and pore throats, it can be divided into three types: pore-dispersed clay, pore-bound clay and pore-bridged clay. Diagenetic facies of authigenic clay minerals in the study area can be divided into A, B and late diagenetic stages A and B + C. In four different diagenetic periods, the combination of authigenic clay minerals is also different. Its vertical evolution can be divided into three zones, ie, serotectonic zone, I / S mixed zone and illite zone. In different transformation zones, the origin and distribution of authigenic clay minerals are also different. Among them, the pore-bridged clay has the greatest influence on the porosity and permeability. The existence of authigenic clay minerals can lead to the migration of particles, absorb or release some cations to form insoluble precipitates, block the pore throats, change the pore structure of reservoirs and affect logging results. In order to reduce the impact of authigenic clay minerals on reservoir characteristics and logging results, some measures to protect the reservoir are proposed in this paper.