Thermal evolution characteristics of source rocks of the Upper Paleozoic in Tabamiao Block in Ordos Basin, China

Coal formation of Taiyuan Formation and Shanxi Formation are source rocks in the northern part of Ordos Basin, and studying on its thermal maturity history is an important reference to forecast gas filling process and favorable target areas. On the basis of source rocks evaluation and 1D and 2D modeling of coal formation in the studying area, thermal evolution history modeling of source rocks in single well and 2D profile and plane of studying area was made using BasinMod software. The results showed that: source rocks entered into hydrocarbon generation threshold in Middle Triassic, continued to bury to the greatest depth (about 4 000 m) from Middle Jurassic to the late stage of Early Cretaceous, the vast majority of natural gas are generated at this stage,and only a small amount of natural gas produced after tectonic uplift of formation in the late stage of Early Cretaceous; cumulative hydrocarbon generation of Taiyuan Formation and Shanxi Formation reached 2 200×10⁸m³/km², which controlled present distribution of natural gas.