Hydrocarbon Kitchen Evolution in the Early Cretaceous Bayingebi 2 Formation in the Chagan Depression, Yingen-Ejinaqi Basin, North Central China.

Abstract

The Chagan Depression is an important oil and gas exploration tectonic unit in the Yingen-Ejinaqi Basin, north central China. It has been revealed that the Chagan Depression has abundant oil and gas resources, but the study of hydrocarbon kitchens has not been carried out. The Early Cretaceous Bayingebi 2 Formation has the most important source rocks in the Chagan Depression. In this paper, the Bayingebi 2 Formation was selected to study the hydrocarbon kitchen evolution. The thermal maturity evolution of the source rocks and the locations and geological time of the development of hydrocarbon kitchens were revealed. The results show that the maturity of source rocks in the Bayingebi 2 Formation has reached the maximum during the middle depositional period of the Yingen Formation, and the hydrocarbon generation has ceased since the Late Cretaceous. The source rocks of the Bayingebi 2 Formation in the Chagan Depression have two hydrocarbon kitchens, namely, the western subdepression and the eastern subdepression hydrocarbon kitchens. The western subdepression hydrocarbon kitchen was formed in the Suhongtu 1 Formation depositional period and ended in the Yingen Formation depositional period. The location of the hydrocarbon kitchen was relatively stable and developed in the central and southern parts. However, the eastern subdepression hydrocarbon kitchen developed only during the Yingen Formation depositional period and was located in the north subsag of the Hantamiao sag zone. Finally, the evolution of the hydrocarbon kitchen reveals that oil and gas exploration still needs to be carried out around the western subdepression hydrocarbon kitchen and it may be considered to abandon the exploration in the eastern subdepression.