四川盆地北部阆中地区茅口组二段白云岩储层特征及主控因素OA

The second member of Maokou Formation(Mao2 member)in Sichuan Basin develops beach facies dolo-mite reservoirs,and several gas wells get high commercial production.However,exploration level of this interval is low in Langzhong area.Core and thin section observation and geochemical analysis are performed to study reservoirs distribution characteristics,diagenesis,pores evolution process and main controlling factors of reservoirs.The re-sults show that Mao2 member mainly develops fine-medium crystalline dolomite reservoirs,and reservoir spaces are mainly dolomite intergranular(dissolved)pores and residual pores in quasi-syngenetic karst system,being general-ly Class Ⅱ and Ⅲ fractured-porous reservoirs.Dolomite reservoirs mainly experienced the processes of syngenetic-quasi-syngenetic submarine cementation and dolomitization,quasi-syngenetic exposure and dissolution,dolomitiza-tion in shallow burial period,and structural fracturing,expansion and cementation filling in medium-deep burial period.The key factor to reservoir development is high-energy grain beach superimposed with quasi-syngenetic ex-posure and dissolution.Large-scale dolomitization in early stage of diagenesis is conducive to pores preservation,while capability to increase storage through burial dissolution and structural fracturing in closed system in middle-late stage of diagenesis is limited.The research provides effective support for next-step optimization of exploration targets in Mao2 member of Langzhong area.