Analysis On Hydrocarbon Accumulation Process Of Cambrian Marine Oil And Gas In The Eastern Slope Of Central Sichuan Paleo-uplift

The Central Sichuan Paleo-uplift in Sichuan Basin has great exploration potential.Because of the great discovering of Anyue and other large gas fields in Central Sichuan,the key area of oil and gas exploration will be gradually transferred to the slope of paleo-uplift.However,the exploration degree of paleo-uplift area zone is low,the diagenesis is complex and lack of well drilling,also the accumulation process of Cambrian reservoir is not clear yet.Therefore,it is of great significance to study the reservoir forming process in the eastern slope area of the Central Sichuan Paleo-uplift for the next petroleum in the Paleo-uplift slope.This paper analyzes the tectonic evolution history of the eastern slope area of the Central Sichuan Paleo-uplift by using regional seismic and logging data to recover the erosion amount of each tectonic movement and the distribution of Cambrian karst topography.In this paper,the erosion amount of carbonate formation of marine faces is recovered by the spectrum analysis method and the clastic rock formation of land faces is recovered by the mudstone acoustic wave method.This paper inverts the regional tectonic evolution process by 3dmove software and discusses the forming process of the slope and the structural control of the reservoir in the study area.The Petro Mod was used to simulate the hydrocarbon generation history,thermal history and burial history of the source rocks,and the favorable areas of Cambrian reservoir in the eastern slope of Central Sichuan Paleo-uplift was discussed by combining with the accumulation periods.The results of the restoration of structural evolution of the study area shows that the study area has experienced three stages: slope formation stage corresponding to Tongwan Episode II to Caledonian,slope adjustment stage corresponding to Hercynian to Indosinianand and slope finalization stage corresponding to Yanshanian to nowadays.The results of karst topography restoration show that the karst highland of Longwangmiao formation is located in the west of the study area,and the karst highland of Xixiangchi formation is located in the north of the study area,which is a favorable zone for the development of Cambrian high-quality reservoirs.Combining the simulation results of hydrocarbon generation history of source rocks with the results of the homogenization temperature of fluid inclusions shows that the Cambrian reservoir in the study area experienced five stages of accumulation.The five stages of hydrocarbon accumulation correspond to oil reservoirs from Early Silurian to middle Silurian,oil reservoirs from early Triassic to Middle Triassic,wet gas reservoirs from Middle Triassic to early Jurassic,dry gas and cracking gas reservoirs from Middle Jurassic to early Cretaceous,and cracking gas reservoirs during the Yanshan and Himalayan periods.The favorable areas of high-quality reservoirs were predicted by recovering the distribution of karst topography.Combining with the position of high-quality reservoir and the position where structural high point of the reservoir was forming in the accumulation period,the upper slope zone of the west of the study area is regarded as the favorable exploration areas of gas reservoirs today.