致密砂岩储集层渗透率预测修正方法

Modified Methods of Permeability Prediction for Tight Sandstone Reservoirs

致密砂岩储集层孔喉细小、孔喉关系复杂,现有的渗透率预测模型常应用于常规砂岩或碳酸盐岩储集层,不能很好地预测致密砂岩储集层的渗透率。选取鄂尔多斯盆地长6—长8油层组的10块致密砂岩岩心,基于矿物分析和扫描电镜等实验,分析了样品的矿物组成与孔喉结构特征;基于高压压汞实验,对8类典型渗透率预测模型的特征参数进行了修正,建立了适用于致密砂岩储集层的渗透率预测修正方法,并对模型进行了优选与适应性评价。研究表明,修正的Pittman模型、Winland模型、Dastidar模型和K-T模型对致密砂岩储集层渗透率具有较好的预测效果;而修正的Purcell模型、Swanson模型、Thomeer模型和W-A模型的预测效果较差。

Tight sandstone reservoir is featured with tiny pore throat and complicated pore throat structure.The available models for reser⁃voir permeability prediction are generally used for conventional sandstone or carbonate reservoirs,which cannot get good permeability pre⁃diction results of tight sandstone reservoirs.10 core samples of tight sandstone obtained from Chang 6-Chang 8 members in Ordos basin are selected and the mineral compositions and pore throat structures of the samples are analyzed based on experiments of mineral analysis and SEM.On the basis of high⁃pressure mercury injection experiment,the paper modifies the parameters for 8 typical reservoir permeabili⁃ty prediction models,establishes modified methods suitable for permeability prediction of tight sandstone reservoirs and carries out model optimization and adaptability evaluation.The results show that the good prediction results for tight sandstone reservoirs can be obtained from the modified Pittman model,Winland model,Dastidar model and K⁃T model,but the prediction results from the modified Purcell mod⁃el,Swanson model,Thomeer model and W⁃A model are relatively poor.