Characteristics Of Tectono-thermal Evolution Of Carboniferous-permian In Songliao Basin

Now the oil and gas production in the shallow layer of Songliao basin is decreasing and the exploration difficulty is increasing.In order to find more oil and gas reservoirs and enhance the reserves of oil and gas resources in China,deep oil and gas exploration in Songliao Basin plays an important role,and the study of basin thermal history and Carboniferous-Permian source rock thermal evolution history is of great significance for deep oil and gas exploration.This paper studies the sedimentary characteristics and geological significance of the Carboniferous-Permian strata in the periphery of Songliao Basin by field geological survey,microscopic observation and major and micro analysis.On the basis of previous studies,the denudation thickness of songliao Basin in geological period is recovered by using various means such as vitrinite reflectance method,fission track method,Easy%Ro method and basin simulation software,and then the burial history,tectonic thermal evolution history and maturity history of Carboniferous-Permian of Upper Paleozoic in different tectonic units of Songliao Basin are recovered.The results show that the mudstone provenance of yangjiagou Formation in Upper Permian is mainly acidic island arc provenance,and the source rock type is sedimentary rock.The sedimentary period is warm and humid continental or freshwater environment,the paleoclimate is warm and humid,the Redox condition is reduction condition,and the tectonic setting is mainly continental island arc and active continental margin.The present ground temperature at 1000 m,2000m and 3000 m in songliao Basin is between 10～60℃,50～100℃and 70～150℃,respectively.The present geothermal gradient is 28.7～62.3℃/km,and the average geothermal gradient is 39.6℃/km.The present geothermal heat flow is 44.3 ～94.9m W/m2,and the average geothermal heat flow is 70.6m W/m2,belonging to the middle-temperature basin.The Carboniferous-Permian strata in the Songliao Basin experienced the highest palaeogeothermal temperature or the greatest burial depth in different geological periods,and even the highest palaeogeothermal temperature or the greatest burial depth in different locations of the same tectonic unit.For example,the Carboniferous-Permian strata in Well Ren 11 in the northeast uplift experienced the highest paleogeothermal temperature of 337℃,which reached in the early Triassic.The maximum paleotemperature of the Carboniferous-Permian strata in well Beican-1 in the northern dumping area was 159℃,which was reached in the late Cretaceous.Combining the previous research and the analysis of the thermal evolution history of Songliao Basin in this paper,the area around the Mingshui terrace in the northeast of the central depression,the south of Sanzhao Sag in the central depression and the well Zhuangshen 1 in the northwest of the southeast uplift area are classified as the type I favorable areas for hydrocarbon generation.The western part of the suiling anticlinal zone,the eastern part of the central depression and the western part of the southeast uplift zone are divided into the favorable areas of type II for hydrocarbon generation.This study provides guidance and help for the exploration of deep oil and gas resources in Songliao Basin,and is of great significance for the prediction of the favorable oil and gas areas of Carboniferous-Permian in Songliao Basin.