CHARACTERISTICS AND MAIN CONTROLLING FACTORS OF TIGHT SANDSTONE RESERVOIR IN THE 4TH SEGMENT OF THE XUJIAHE FOR-MATION,EASTERN AREA OF SICHUAN BASIN
The Xujiahe Formation in the Sichuan Basin serves as a crucial reservoir for tight oil and gas exploration.However,while previous studies have mainly focused on the western-central area of the Si-chuan Basin,the 4th segment of the Xujiahe Formation(T3x4)in the eastern area has received little atten-tion.In particular,understanding its basic reservoir characteristics and controlling factors has remained unclear,thus impeding subsequent research and oil and gas exploration efforts.Through field cross-sec-tion studies and analysis of drilling core samples,rock thin sections,cast thin sections,and scanning elec-tron microscopy,this research delves into the petrology characteristics,pore characteristics,physical characteristics,and primary controlling factors of reservoir development in T3x4 in the eastern area of the Sichuan Basin.The findings reveal that the T3x4 reservoir sandstone in the eastern area mainly comprises medium-coarse-grained feldspar quartz sandstone and lithic quartz sandstone,characterized by a porosity ranging from 2％to 8％(averaging 5.11％)and permeability of(0.01-0.10)X10-3 μm2,indicative of a tight sandstone reservoir.While both diagenesis and sedimentation influence the physical properties of the reservoir,diagenesis is the primary determinant.The original porosity of the T3 x4 reservoir sandstone is 34.58％,with diagenetic compaction reducing it to 6.25％,and cementation further diminishing it to 3.33％.Feldspar and clast dissolution emerge as the primary pore-increasing factors,resulting in a 1.78％increase in pore volume of the reservoir sandstone.The amalgamation of these diagenetic processes under-lies the formation of the T3x4 tight sandstone reservoir.In the study area,medium-coarse-grained sand-stone developed in the primary channel exhibits the most favorable physical properties,with an average porosity of 6.67％.Estuarine bar and sheet sand microfacies sandstone rank second,with an average po-rosity of 6.1％.Conversely,microfacies sandstone in interdistributary bays exhibits poor physical proper-ties,with an average porosity of 3.53％.These research outcomes provide valuable reference and support for the investigation of tight sandstone reservoirs and oil and gas exploration endeavors.
reservoir characteristicscontrolling factorsthe 4th segment of Xujiahe Formationeastern area of Sichuan basin
万方数据
维普
