基于岩性分类的混积页岩油饱和度计算方法

Calculation Method of Oil Saturation of Mixed Shale Based on Lithology Classification

准噶尔盆地吉木萨尔凹陷二叠系芦草沟组混积页岩油甜点岩性种类多、矿物成分复杂、非均质性强,基于常规测井的参数利用阿尔奇公式计算含油饱和度精度低。以研究区岩心、岩石薄片、测井资料为基础,采用岩心刻度测井、聚类分析、数据挖掘及分布交会的方法,依据岩性主成分将20余类岩性归类为9类岩性,挖掘常规测井敏感参数,构建了混积页岩油常规测井岩性识别标准;基于页岩油甜点七性关系及阿尔奇公式饱和度主控因素认识,明确了5类页岩油甜点优势岩性,分岩性确定孔隙度模型和岩电参数;采用密闭取心资料分析含油饱和度并结合岩电参数反算求得地层水电阻率,构建了混积页岩油不同岩性的含油饱和度计算模型。应用到混积页岩油有效厚度储层含油饱和度的计算,将计算的含油饱和度与岩心分析含油饱和度对比,平均误差为2.06%,符合储量标准小于5.00%的要求,为混积页岩油常规测井高精度含油饱和度的计算提供新的思路和方法。

The mixed shale oil sweet spot of Permian Lucaogou formation in Jimsar sag,Junggar basin has many lithology types,complex mineral composition and strong heterogeneity,and the accuracy of oil saturation calculated with conventional logging by Archie formula is low.On the basis of core,thin section and logging data in the study area,more than 20 lithologies are classified into 9 lithologies according to lithology principal components by core calibration logging,cluster analysis,data mining and distribution intersection,and the sensitive parameters of conventional logging are excavated to establish the lithology identification standard of conventional logging of mixed shale oil.Based on the seven relationships of shale oil desserts and the main controlling factors of saturation of Archie formula,the dominant lithology of 5 types of shale oil desserts is defined,and the porosity model and petroelectric parameters are determined by lithology.The oil saturation calculation model for different lithologies of mixed shale oil is established by using closed coring analysis and inverse calculation of formation water resistivity combined with rock electrical parameters.Applied to the calculation of effective thickness oil saturation of mixed shale oil,the average error between calculated oil saturation and core analysis oil saturation is 2.06%,which is higher than 5.00%of the reserve standard.Which provides a new idea and method for calculating high-precision oil saturation in conventional logging of mixed shale oil.