Genetic Mechanism Analysis on Oolitic Reservoir of Lower Triassic Feixianguan Formation in the Shunan Area,Sichuan Basin

Through research on the oolitic reservoir of Feixianguan Formation in the Shunan Area,Sichuan Basin,it is indicated that the main reservoir spaces of oolitic reservoir are moldic pore and intragranular dissolved pore,which is formed by meteoric water leaching.The reservoir development in the upper part of Oolitic Beach,with obvious characteristics of separated layer stimulation.Combining the study of palaeogeomorphology,eustatic sea level change,palaeoclimate and diagenetic evolution,it is calculated that the mode of origin of oolitic reservoir is syngenetic karst,reservoir is formed by meteoric water leaching.Oolitic beach at the chapada of palaeogeomorphology provided material basis for the reservoir formation and evolution,and controlled the distribution of reservoir.Paleogeomorphology,eustatic sea level change and palaeoclimate determined the intensity of syngenetic karst,and dominated reservoir quality.Subjacent karst and tectonic disruption play a role in improving reservoir performance,but is limited in effect.