流动单元在潮坪相碳酸盐岩储层中的应用:以川西气田雷四3亚段为例

Application of Flow Unit in Tidal Flat Carbonate Reservoir: A Case of the Upper Part of the Fourth Member of Leikoupo Formation in the Western Sichuan Gas Field

四川盆地川西气田雷四3亚段潮坪相碳酸盐岩储层经历了复杂的沉积、成岩及多期岩溶作用改造,纵横向非均质性强,储层流动单元划分研究比较薄弱。通过岩心、岩屑、薄片和测井资料,总结不同沉积微相的测井响应模式,分析岩相与储集空间类型、物性之间的关系,并筛选出岩相敏感测井曲线;优选储层品质参数(RQI)和岩相敏感测井曲线自然伽马(GR)、深侧向电阻率(RD)等参数利用聚类分析将川西气田雷四3亚段潮坪相碳酸盐岩储层划分为3类流动单元,储层岩性特征和物性特征的结合,形成了综合考虑岩相、孔渗特征、储集空间类型等参数的流动单元划分标准及采用多参数聚类、判别分析快速划分流动单元的方法。该方法既考虑了储层形成的原生沉积作用,又兼顾了该类储层多期岩溶作用改造后的物性变化,岩相、物性和储集空间类型的综合能有效避免流动单元划分的多解性。将流动单元宏观上渗流特征用微观孔隙结构进行对比验证。结果表明:该方法对川西气田雷四3亚段潮坪相碳酸盐岩储层流动单元划分具有较好的应用效果,可为储层品质评价、提高储层评价的精度和开发方案的制定提供依据。

The tidal flat carbonate reservoir in the upper part of the fourth member of Leikoupo Formation of West Sichuan Gas Field in Sichuan Basin has experienced complex sedimentation and multi stage post diagenetic karstification,with strong vertical and horizontal heterogeneity,and the study on the division of reservoir flow units is relatively weak.Based on core,cuttings,thin sections and logging data,summarize logging response models of different sedimentary microfacies,the relationship was analyzed between lithofacies and reservoir space types and physical properties,and screen out lithofacies sensitive logging curves.The tidal flat facies Carbonate rock reservoir in the upper part of the fourth member of Leikoupo Formation of West Sichuan Gas Field was divided into three types of flow units by cluster analysis based on the optimization of reservoir quality index(RQI),natural gamma logging curve(GR),deep lateral resistivity logging curve(RD)and other parameters.The combination of lithological characteristics and physical characteristics of the reservoir,comprehensive consideration of lithofacies,porosity and permeability characteristics,reservoir space type and other parameters,formed the flow unit division standard,and a method was proposed for rapid division of flow units by using multi parameter clustering and discriminant analysis.The proposed method not only considers the primary sedimentation of reservoir formation,but also takes into account the physical property changes of this type of reservoir after multi-phase karstification.The combination of lithofacies,physical property and reservoir space type can effectively avoid the multi solution of flow unit division.The macroscopic seepage characteristics of flow units were compared with the microscopic pore structure.The research results show that the proposed method has a good application effect on the division of flow units of tidal flat carbonate reservoirs in the upper part of the fourth member of Leikoupo Formation of West Sichuan Gas Field,and can provide a basis for reservoir quality evaluation,improving the accuracy of reservoir evaluation,and formulating development plans.