Development And Main Controlling Factors Of Reservoir In The Jialingjiang Formation,Southern Sichuan Basin

South Si Chuan Gasfield developed multiple favorable traps,such as Maliuchang,Ziliujing and Lingyinsi,in the Jialingjiang Formation in southern Sichuan.At present,the proved reserves of the Jialingjiang Formation are less than one-third of the resources of the traps,which reveals that the natural gas of the Jialingjiang Formation in southern Sichuan has a good prospect of exploration and development.Therefore,it is of great significance to clarify the development and distribution of the reservoirs of the Jialingjiang Formation for further exploration in southern Sichuan Basin.Based on the theory of carbonate sedimentology,carbonate reservoir geology and sequence stratigraphy,this paper makes full use of drilling and logging,core and thin section data to study the sequence,sedimentary facies,reservoir characteristics and diagenesis of the Jialingjiang Formation in southern Sichuan Basin,and further analyzes the development,distribution and main control factors of the reservoirs.The results show:(1)the Jialingjiang Formation can be divided into two third-order sequences,six fourthorder sequences and sixteen fifth-order sequences;(2)the Jialingjiang Formation is mainly developed eight subfacies(open subtidal zone,with restricted lagoons,restricted terraces,granular beaches,evaporated lagoons and evaporated terrace subfacies);(3)the Jialingjiang Formation is developed with shoal reservoirs and restricted terrace reservoirs,of which shoal reservoir is the main type and restricted terrace reservoir less development.The lithology of shoal reservoirs are grain limestone and grain dolomite,and the main reservoir space is intergranular solution hole and intragranular solution hole(mold hole).The rock types of limited Taiping reservoir are micritic dolomite and gypsiferous dolomite,and the main reservoir space is intergranular hole,intergranular solution hole and gypsum mold hole;(4)the main diagenesis types of the reservoir are compaction,pressure dissolution,cementation,dissolution,dolomitization,and rupture.Based on the analysis of diagenesis,diagenesis sequence and reservoir pore evolution model are established;(5)the shoal is the material basis of reservoir development,which is controlled by sequence and sedimentary paleogeomorphology,mainly developed vertically in the middle and lower part of highstand system tract,and mainly distributed in the plane above Luzhou paleouplift.Diagenesis is the key to the further evolution of granular beach into reservoirs.The main destructive diagenesis of shoal reservoir is compaction,pressure dissolution and cementation,the main constructive diagenesis is dissolution and dolomitization,and the fractures produced by structural movement further improve the reservoir performance.