Thermal History Reconstruction of Mesozoic Source Rocks in Western of Suhongtu Depression,Inner Mongolia,Northern China
Qi Kai
Ren Zhanli
Cui Junping
Chen Zhipeng
Ren Wenbo
Abstract：Suhongtu depression,located in the northeastern of Yin'e basin (Yingen-Ejinaqi basin),is a Mesozoic faulting-subsiding basin with large oil and gas resources.75 vitrinite reflectance data from 7 wells in the study area are used to analyze the degree of thermal evolution of Mesozoic source rocks.The thermal evolution degree of source rocks in Yingen Formation is in immature to low mature stage.The vitrinite reflectance (Ro)data distribute in 0.6%—1.2% at the bottom of Suhongtu For-mation,and they are generally greater than 1 .1% at the bottom of Bayingebi Formation in the center of the sag.The results of Mesozoic and Cenozoic thermal history show that the present-day geothermal gradient is 34 ℃/km,and approximately 40.6—46.7 ℃/km in Late Cretaceous.The temperature gradient was 40—42 ℃/km (135—110 Ma)and increased to 46—50 ℃/km (110—103 Ma).Especially,during the deposition period of Yingen Formation (100—95 Ma),the geothermal gradient reached the maximum at about 48—53 ℃/km.From the beginning of Wulansuhai Formation,the geothermal gradient gradually in-creased to 40—46 ℃/km (92—80 Ma)and decreased to a present-day value of 34 ℃/km (80—0 Ma)ultimately.The higher geothermal field has played an important role in controlling oil and gas generation and accumulation since the Early Cretaceous, and the source rocks have reached the maximum thermal evolution stage at the end of the sedimentary period of the Wulansuhai Formation.
Keywords：thermal history reconstructionthermal evolution of source rockvitrinite reflectanceMesozoic-CenozoicYin'e basinpetroleum geologytectonics
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 1957-1971 )