低孔低渗储层中岩电参数的修正

摘要

The lithological electrical parameters in Archie formula are relative as opposed to fixed and isolated.The li-thological electrical experimental results obtained from 28 pieces of hydrophilic sandstones show that the lithological elec-trical parameters in low porosity samples are distinctly different from those in high porosity samples.The relationship be-tween formation factor and porosity is not the Archie linear relation,but a quadratic function relationship.The cementation index,which is not a fixed value,is a function of porosity.The saturation index is greatly influenced by the salinity of for-mation water,and increases with the increasing of formation water salinity.Based on the lithological electrical experimental results of the research area,the electrical parameter values in low porosity and high porosity rock are confirmed separately, and the common Archie formula is corrected and optimized.In the comparison of the water saturation and irreducible water saturation calculated by the revised model in reservoir section of study area,the absolute error reduced to 3.40%,showing that the water saturation calculated by the modified rock electrical parameters is more accurate,and can be used for the quantitative evaluation of actual logging.%阿尔奇公式中的岩电参数并不是固定的、孤立的。通过28块亲水性砂岩的岩电实验结果得出，低孔隙样品的岩电参数明显不同于中高孔隙样品，地层因素与孔隙度在双对数坐标下并不满足经典的阿尔奇线性关系，呈二次函数关系，胶结指数为孔隙度的函数，不为固定值；另外饱和度指数都受地层水矿化度的影响较大，并且随地层水矿化度的增大而增大。根据研究地区的岩电实验结果，分别确定了低孔隙度和中高孔隙度下岩电参数的取值，修正并优化了常用的阿尔奇公式。通过修正后的模型在研究地区油层段计算的含水饱和度与束缚水饱和度的比较中，绝对误差降低到3.40％，表明经修正后的岩电参数计算的含水饱和度更加精准，可用于实际的测井定量评价。