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利用扫描电镜和常规酸敏实验等岩矿测试手段,分析了川中某气田须家河组富含伊利石的低渗透砂岩储层的酸化效果,系统对比了酸化流动实验前后伊利石微观结构特征的变化。常规酸敏实验结果表明,盐酸酸敏程度为中等偏强,土酸酸敏程度为强。伊利石经过盐酸酸化后,晶形基本无变化。伊利石经过土酸酸化后,出现了不同程度的溶蚀:半充填孔隙的片状伊利石被溶蚀后倒塌,附着在岩石颗粒上,增大了储层孔隙体积;晶体遭受部分溶蚀,晶形模糊;酸化后产生的微粒物质附着于伊利石表面。土酸酸化破坏了岩心的原生结构。通过毛管流动孔隙结构仪测试酸化前后孔隙结构参数,表明酸化后储层有效喉道大小没有得到明显改善。
The acidification effects of illite-rich low-permeability sandstone reservoirs in Xujiahe Formation of a gas field in central Sichuan Basin were analyzed by means of rock and mine tests such as scanning electron microscopy and conventional acid-sensitive experiments. The microstructural characteristics of illite were compared systematically Variety. Conventional acid-sensitivity test results show that the acid sensitivity of hydrochloric acid is moderately strong, strong acid soil acidity. After the illite was acidified by hydrochloric acid, the crystal form was almost unchanged. After the acidification of illite, different degrees of corrosion appeared: the sheet-like illite with semi-filled pores collapsed after being dissolved and adhered to the rock particles, which increased the pore volume of the reservoir; the crystal was partially dissolved and the shape of the crystal was blurred; The acidified particles are attached to the surface of the illite. Soil acidification destroyed the core structure of the core. The pore structure parameters before and after acidification were measured by capillary flow pore structure analyzer, which showed that the effective throat size of the reservoir did not improve obviously after the acidification.