Comprehensive Evaluation Of Gas Accumulation In Shaximiao Formation In Western Sichuan

Based on the comprehensive study of traditional petroleum geology and the guidance of oil and gas distribution threshold theory,this paper conducts a comprehensive evaluation study on the formation of natural gas reservoirs in the Shaximiao Formation in the western Sichuan area,which improves the accuracy and optimization of the prediction and optimization of exploration targets rationality.Using fluid inclusion analysis technology,erosion recovery technology and other technologies,based on previous research results,combined with seismic data,drilling data and physical property data,through typical gas reservoir anatomy,the structure and sedimentation characteristics,tectonic evolution characteristics and the characteristics of the transmission system,the gas accumulation mode,the accumulation control factors,the favorable accumulation zones and the characteristics of the accumulation differences are studied.By the natural gas accumulation model and the control factors of natural gas accumulation in the Shaximiao Formation in the western Sichuan area,a reasonable natural gas accumulation evaluation system was established,and comprehensive natural gas accumulation evaluation was conducted in each zone using reasonable natural gas evaluation standards and corresponding control function elements.The study shows that the whole early and middle stage of Yanshan movement is dominated by nearly SN-direction compression,with NE-SW conjugate translational reverse faults developed,and the EW oriented tectonic belt is formed from north to south;And lateral compression,the formation of structural belts,the development of SN-thrust faults,and the overall uplift in the western Sichuan area during the Himalayan movement;Pingluoba,Baimamiao,and Guanyinsi structures have good sand matching relationships and good reservoir connectivity;The Shaximiao Formation gas reservoir has two stages of oil and gas charging.The early charge reservoir has been damaged.The accumulation time is mainly concentrated in the end of the Yanshan movement and the early Himalayan movement.Hydrocarbon inclusions should represent the late stage affected by tectonic movements,and then hydrocarbon accumulation after adjustment;The accumulation process of Shaximiao Formation in western Sichuan is generally a model of “structural control direction,fault sand control migration,reservoir control accumulation,evolution control adjustment”.According to the combination of "CMFS" and "CDMS",the three-level favorable exploration areas can be divided in the southwestern Sichuan area and the northwest Sichuan area.Thenatural gas reservoirs of Shaximiao Formation in southwestern Sichuan are mostly controlled by factors such as lithology,structure,and faults,and the structures are mostly inherited ancient structures,and the gas reservoirs are weakly adjusted.The natural gas reservoirs in the Shaximiao Formation in the northwestern Sichuan area are mostly controlled by lithology and structure,and there are few faults.Therefore,there is a large difference in reservoir formation between the southern and northern Sichuan Basin.