数字岩心技术在致密砂岩储层含油饱和度评价中的应用

基于适用于纯砂岩储层的阿尔奇公式计算的致密砂岩储层含油饱和度精度低．适用性差。将多点地质统计学和以自相关函数为基础的数字图像重构技术进行结合，形成能够描述储层复杂孔隙结构特征的低渗透储层数字岩心建模技术，应用建立的数字岩心，通过数值模拟，研究了储层孔隙结构类型、泥质质量分数和地层水矿化度等因素对阿尔奇公式中饱和度指数和胶结指数等参数的影响。研究认为，储层粒间孔隙、裂缝孔隙和孤立的溶孔隙等因素对阿尔奇参数影响巨大．裂缝孔隙度和地层水电阻率增大会导致胶结指数和饱和度指数减小．孤立溶蚀孔隙度和泥质质量分数增加会导致胶结指数和饱和度指数增大。利用孔隙结构特征参数与饱和度指数、胶结指数的关系，建立变参数的阿尔奇公式可提高饱和度计算精度．

Application of digital core technology in oil saturation appraisal of tight sandstone reservoir

The accuracy of oil saturation calculated using Archie equation which is based on clean sandstone is low and the applicability is poor. Multipoint geostatistics is combined with digital image reconfiguration technology based on auto-correlation function to establish digital core modeling teehnology of complex pore structure. Using the digital core established, this paper numerically simulates the influences of pore structure types, shale content and formation water salinity on the saturation and cement exponents in Archie equation. The analysis results show that the intergranular pore, fracture pore and insulated dissolved pore affect Archie parameters greatly. The increasing of fracture and formation water resistivity leads to the decreasing of cement exponent and saturation exponent. But the increasing of insulated dissolved pore and shale content is totally opposite. By establishing the pore structure characteristics and the relationship between saturation and cement exponents, the aceuraey of saturation can be improved using the varying parameter Archie equation.