Reservoir Characteristics And Main Controlling Factors Of Feixianguan Formation In Xuanhan-Daxian Area, Northeastern Sichuan

Repeatedly summaries and analysis of predecessors' research results,this paper through carefully observing the core and the field profiles,combining with seismic,well logging,sedimentary cycle and data of reservoir to study the Feixinguan formation,reservoir characteristics and main control factors.The results showed that Feixianguan formation conformable contact with the underlying Changxing formation and overlying Jialingjiang formation.It can be divided into four members from bottom to top.The first-second member is characteristic by platform margin beach deposits.The third member is restricted platform deposits and the fourth member evolution of evaporite sedimentary environment.In the same time,Feixianguan formation has different facies.Different area has different distributions of lithologic,and the stratigraphic distribution is closely related to sedimentary facies.Great strata thickness in deep-water areas,and thin strata thickness in shallow water.According to the reservoir characteristics analysis,the main reservoir rock types in Feixianguan formation are residual oolitic dolomite,oolitic dolomite,residual arenite dolomite,arenite dolomite,granulated sugar dolomite and crystalline dolomite.The reservoir space types mainly include intercrystalline pores,intercrystalline dissolved pore,intergranular dissolved pore,mold hole,cave,cracks,and a small amount of intracrystalline solution pores.The total average porosity is seven point seven percent,which is given priority to five percent to ten percent and greater than ten percent.The total average permeability is 108.801× 10-3?m2,which is given priority to greater than 1×10-3?m2.Pores are focused on macroporous and throat is given priority to with coarse throat.Porosity and permeability has a good positive correlation,and the reservoir density has negative correlation between the porosity and permeability,instructions for the reservoir pore type.Reservoir is mainly affected by sedimentary facies,diagenesis,tectonic movement and the matching of multiple factors.The favorable sedimentary facies control advantageous rock type and its distribution.The occurrence of tectonic activity will promote favorable diagenesis in rock.Favorable diagenesis will lead to the formation and evolution of the pores of the rock.The matching of multiple factors will lead to easier form high quality reservoirs.Through the analysis of the diagenetic stages and diagenetic environment establishing porosity evolution model of different rocks types that are advantageous to the reservoir development.It includes grain beach dolomite,grain beach limestone and putty crystal to powder crystal dolomite.The results show that the development of pores in grain beach dolomite is the best after Exposure to seafloor-buried karst environment,and the reservoir quality also the best.Carefully researching Feixianguan reservoir characteristics in different zone,on the basis of carbonate reservoirs evaluation standard in Sichuan basin,to evaluate each parts reservoir and classify different types of reservoirs.At the same time,in combination with sedimentary background,the study area is divided into favorable reservoir distribution area and the relative favorable reservoir distribution area.The favorable reservoir distribution area mainly in the line of Maobao area to Dawan area to Puguang area on the plane.its sedimentary faciesis platform edge exposed grain beach facies.The relative favorable reservoir distribution area mainly in the platform edge grain beach facies of Laojun area and the grain beach in the restricted platform facies zone on the east of Puguang area.