强非均质性碳酸盐岩气藏储渗体精细描述及高效开发技术攻关与实践OA

Accurate identification and characterization of reservoir-seepage units(RSUs)can reveal the matching relation between static geological elements and production dynamic characteristics,and thus improve the development benefits of highly heterogeneous carbonate gas reservoirs in production plateau.Therefore,this study investigated the gas reservoir in the fourth member of the Upper Sinian Dengying Formation(Deng-4 Member)in the platform-margin belt of the GM block,Anyue Gasfield,Sichuan Basin.Guided by the concept combining production dynamic characteristics and static geological understanding(dynamic-static combination for short),the RSUs were finely characterized,and the development flow units(DFUs)were thoroughly analyzed,based on the identification and classification of RSUs,as well as seismic,geological,and production data.Furthermore,the remaining producible reserves in different DFUs in the study area were systematically evaluated.The following research findings are obtained.(i)Three types of RSUs are identified:Type Ⅰ,dominated by fractured-vuggy reservoirs with high flow conductivity;Type Ⅱ,primarily composed of vuggy reservoirs with pore-throat structure;and Type Ⅲ,mainly consisting of isolated porous reservoirs.Types Ⅰ to Ⅲ rank in a descending order of reservoir and flow capacity,and Types Ⅰ and Ⅱ are defined as high-quality RSUs.(ii)High-quality RSUs show remarkable heterogeneity of spatial distribution,and their development scale is a key geological determinant for high and stable production of gas wells.(iii)The study area is divided into four Type Ⅰ,one Type Ⅱ,and two Type Ⅲ DFUs,according to the characteristics and dynamic responses of RSUs.The remaining producible reserves are mainly enriched in the Type Ⅱ and Ⅲ DFUs.It is concluded that,the differentiated development strategy based on"categorized optimization and targeted measures"is an effective option to address the geological element and production performance complexities in highly heterogeneous gas reservoirs;the closed-loop research approach incorporating update of geological models,integration of engineering technologies,and continuous optimization of dynamic-static combination is crucial to ensure efficient development of such reservoirs.