低孔渗泥质砂岩有效介质三水导电模型的应用

APPLICATION OF THE EFFECTIVE MEDIUM THREE-WATER CONDUCTIVE MODEL FOR LOW POROUS AND PERMEABLE SHALY SAND

针对大庆扶杨低孔渗泥质砂岩储层微孔隙发育、束缚水饱和度大、粘土附加导电作用强的特点,基于三水概念和有效介质对称各向异性导电理论,建立了低孔渗泥质砂岩有效介质三水导电模型。通过研究模型求解含水饱和度方法,表明模型导出的关于可动水孔隙度函数在零至有效孔隙度区间内存在一个局部极小值,且该极小值点对应的孔隙度随骨架渗滤指数、微孔隙水渗滤指数、骨架渗滤速率、微孔隙渗滤速率及其他参数的变化而变化,为保证迭代收敛,采用牛顿和二分结合的混合迭代算法,试算结果表明其收敛。通过岩心实验,给出了微孔隙水和粘土水饱和度确定方法以及渗滤指数和渗滤速率值。利用该模型处理了实际井资料,并将处理结果与试油结果进行对比,表明本文建立的模型可提高大庆扶杨低孔渗泥质砂岩储层评价精度,满足油田勘探开发的需要。

Since Daqing Fuyang shaly sand reservoirs with low porosity and permeability are characterized by more capillary porosity,higher irreducible water saturation,stronger clay access conduction,an effective medium three-water conductive model for low porous and permeable shaly sand has been proposed,based on concept of three water,symmetrical anisotropic effective medium theory.By solving t effective medium three-water conductive model for low porous and permeable shaly sand,it is shown that,there is a local minimum of the function for free water porosity derived from the model in the range from zero to effective porosity,and the free water porosity corresponding to the minimum varies with percolation exponent or water percolation rate as well as other parameters.Therefore,in order to ensure the iteration convergence,we adopt a hybrid algorithm with Newton and bisection methods.The calculated result shows that the hybrid algorithm for obtaining free water porosity is convergent.Furthermore,we employ sample experimental data from low resistivity reservoirs to confirm the model for clay bound water saturation,percolation exponent and percolation rate.The interpretation results for log data of Daqing in China using the proposed method are given,and are compared with test results.It is shown that the water saturation calculated with the model is reasonable.The proposed model can improve the accuracy of the evaluation for Daqing FuYang shaly sand reservoirs with low porosity and permeability,and meet the needs of exploration and development for Daqing oil field.