A Study on Maturation Evolution of Lower Silurian Marine Hydrocarbon Source Rocks and Thermal History in the Southern Jianghan Basin

Abstract

AbstractThe data from typical boreholes in the southern Jianghan basin were modeled using the geothermal history simulation system of hydrocarbon‐bearing basin, and the thermal history and burial history were reconstructed. Based on the thermal history, maturation evolution of the Lower Silurian source rocks was modeled. The results show that the basin was in a stable stage before Indosinian movement, the paleo‐heat flow was between 50 mW/m2 and 55 mW/m2. After Indosinian period, the heat flow was elevated in the whole basin. In Yanshan period (155 Ma or so), the heat flow reached the maximum values of ~72 mW/m2 at 155 Ma in the north of the Qianbei Fault, the heat flow reached the maximum values of ~76 mW/m2 at 40 Ma in the south of the Qianbei Fault. Since the late Himalayan epoch, the Jianghan basin was subjected to a deposition withering period accompanied by a cooling episode. In early Triassic, the maturation of source rocks in Zhijiang, Dangyang and Mianyang depression area first reached oil generation threshold. The maturation of source rocks increased rapidly during early Jurassic to early Cretaceous. The maturation was higher in the north of the Qianbei Fault than in the south. Based on this, in late Cretaceous, the maturation of source rocks in the east area were higher than in the west area. The thermal evolution of source rocks terminated in the late Neogene. The heat flow history and Lower Silurian source rocks maturation evolution was calculated, which provides the basic data for source rocks evolution, hydrocarbon generation and expulsion prediction.