济阳坳陷特低渗透油藏地质多因素综合定量分类评价

Comprehensively Quantitative Reservoir Classification and Evaluation Based on Geological Multivariate Analysis of Extra-low Permeability Reservoirs in Jiyang Depression

在定量表征特低渗透油藏开发效果及地质特征的基础上,探讨特低渗透油藏开发效果主控地质因素。应用灰色关联分析法对济阳坳陷特低渗透油藏开展地质多因素综合定量分类评价,形成了一套以开发效果表征特低渗透油藏综合特征、从单井到区块基于灰色关联分析的特低渗透油藏地质多因素综合定量分类评价方法。研究结果表明,济阳坳陷特低渗透油藏主要为滩坝砂、浊积岩、砂砾岩沉积,具有埋藏深度大、粒度细、分选较好、孔喉微细、单层厚度薄、分布零散、比储量丰度低、流动性差的地质特点。定义累积产油差表征开发效果以反映特低渗透油藏综合特征,其主控地质因素为油层厚度层数比、砂岩厚度层数比、平均粒径、采油段中深、渗透率、孔隙度、比储量丰度。通过地质多因素综合定量分类评价,将济阳坳陷特低渗透油藏分为3类：Ⅰ类综合评价分数大于0.6,累积产油差大于4 500,开发效果最好;Ⅱ类综合评价分数0.4-0.6,累积产油差-2 500到4 500,开发效果中等;Ⅲ类综合评价分数小于0.4,累积产油差小于-2 500,开发效果差。利用不同区块已有开发数据检验,分类评价结果与实际生产情况一致性良好。Ⅰ类、Ⅱ类特低渗透油藏应该作为现阶段特低渗透油藏直井、水平井优先开发的对象。

On the basis of quantitative characterization of development effect and geological features of extra-low permeability reservoirs,the main controlling geology factors of development effect are analyzed.And the grey correlation analysis is used to classify and evaluate the extra-low permeability reservoirs in Jiyang Depression comprehensively and quantitatively together with geological multivariate analysis.Finally,it forms a comprehen-sively quantitative classification and evaluation method based on geological multivariate analysis for extra-low permeability reservoir.The key technologies of this method are the use of development effect to characterize comprehensive feature of extra-low permeability reservoir,the application of grey correlation analysis,and research transiting from single well to blocks.The result shows that sedimentary facies of extra-low permeability reservoirs in Jiyang Depression are mainly beach-bar sands,turbidites and sandy conglomerates.And extra-low permeability reservoirs have the geological characteristics of great burial depth,fine and uniform size,slim pore throat,single-layer thin thickness and scattered distribution,low ratio reserve abundance and poor fluidity.The item of cumulative production deviation is defined to characterize development effect,and it is used to reflect comprehensive features of extra-low permeability reservoirs,and it’s main controlling geological factors are thick-ness layer ratio of oil layer,thickness layer ratio of sandstone,mean grain size,reservoir middle-depth,perme-ability,porosity and ratio reserve abundance.Extra-low permeability reservoirs in Jiyang Depression can be gen-erally divided into 3 different types based on comprehensively quantitative reservoir classification and evaluation. As for typeⅠ,the comprehensive evaluation score is greater than 0. 6 and cumulative production deviation is greater than 4,500,and it has the best development effect.The comprehensive evaluation score of typeⅡran-ges from 0. 4 to 0. 6 and cumulative production deviation varies between -2,500 and 4,500,and it has medi-um development effect.The comprehensive evaluation score of type Ⅲis less than 0. 4 and cumulative produc-tion deviation is less than -2,500,and its development effect is worse.By making full use of development data in the study area to test the result,it is found that classification and evaluation result is in accordance with actu-al production.TypeⅠand typeⅡof extra-low permeability reservoirs should be the preferential object for devel-opment and production of vertical well and horizon well at present.