Reservoir Characteristics And Favorable Area Prediction Of Qixia Formation In Shuangyushi Area,Northwest Sichuan

In this paper,the carbonate rocks of the Middle Permian Qixia Formation in the shuangyushi area of Northwest Sichuan Province are taken as the research object,guided by the theories of petroleum geology,sedimentology,reservoir geology,etc.,and on the basis of previous studies,we make full use of drilling,logging,seismic,core and field profile data as well as slice analysis,scanning electron microscopy,physical properties,mercury intrusion,X-ray diffraction and other analysis and testing methods In the study area,the sedimentary microfacies,reservoir characteristics,main controlling factors of reservoir development and prediction of favorable exploration areas of Qixia Formation are systematically studied,and the following aspects are obtained:(1)According to field profile observation,drilling core description,logging and seismic data,it is identified that Qixia Formation in the study area mainly develops platform margin facies belts and numerous subfacies and microfacies types.On the basis of correlation of sedimentary facies profiles,plane distribution characteristics and longitudinal evolution analysis of sedimentary facies in Lianjing,the evolution of transgression-regression cycle of Qixia Formation of Middle Permian in Pisuoshi area of northwest Sichuan was further revealed,and the sedimentary model of "multi-beach wide and gentle platform margin" was established.(2)The reservoir rocks of Qixia Formation in shuangyushi area,Northwest Sichuan are mainly grain dolomite,grain dolomite and grain limestone,among which grain dolomite and grain dolomite pores are the most developed.The main reservoir spaces are mainly intergranular pores,intergranular dissolution pores and dissolution pores,followed by fractures,with a small number of intergranular dissolution pores and intergranular dissolution pores,which belong to low,ultra-low porosity and ultra-low permeability reservoirs.(3)The reservoir of Qixia Formation in shuangyushi area of Northwest Sichuan is mainly affected by sedimentary microfacies and diagenesis,and fractures also effectively improve the permeability of the reservoir.Among them,the platform margin-detritus beach subfacies are the basis of high-quality reservoir development,dolomitization,dissolution and fracture are the key factors of reservoir formation.(4)According to the above research results,combined with sedimentary microfacies,reservoir thickness,source cap conditions and trap data,three types of favorable areas are selected: type I area is the preferred exploration and development area;type II area is the exploration and development area,and type III area is the exploration risk area,of which type I area and type II area should be the key areas for the next exploration and development.