四川盆地丹凤场地区二叠系茅口组岩溶储层主控因素和有利区评价OA

The lack of systematic research on Maokou Formation karst reservoirs in Danfengchang area of Sichuan Basin constrains the progress of oil and gas exploration and development,and urgently needs determination of reser-voir development characteristics and main controlling factors of productivity.Based on cores,logging and seismic data,the rock types,reservoir space,properties,distribution and main controlling factors of karst reservoirs are an-alyzed,and reservoir favorable areas are divided by areally overlapping main controlling factors.The results show that karst reservoir of Maokou Formation is mainly composed of bioclastic limestone and algal limestone,with reser-voir space dominated by vugs,intergranular dissolved pores,structural fractures and dissolution fractures,being ultra-low porosity-ultra-low permeability reservoir.Karst reservoir is divided as upper member and lower member.Upper reservoir mainly developed in Mao3 member and Mao2a sub-member,while lower reservoir mainly devel-oped in Mao2b sub-member.With maximum thickness up to 19 m,upper reservoir is superior to lower reservoir in scale.The development of karst reservoirs is mainly controlled by 3 factors,including development degree of high-energy grain-beach,karst paleogeomorphology types and faults assemblage styles.Among them,faults assemblage style has major impact on reservoir karstification.2 types of favorable areas are defined.Class Ⅰ favorable area has the best exploration potential,and high-production wells mainly distribute in this area,located 200～1 000 m away from fault.Class Ⅱ favorable area has certain exploration potential.The research can effectively guide further explo-ration and development in this area.