Hydrocarbon Generating Mechanism And Potential In Kongnan Area Of Huanghua Depression

On the basis of theory and methods of petroleum geology and geochemistry, this paper analyzes the mechanisms and resources of Mesozoic and Cenozoic source rocks in the area of Kongnan. Dark mudstones and shales of Ek2 are recognized as the main source rocks by means of comprehensive source-rock evaluation and oil-source correlation. It is indicated from simulation experiment of oil generation and expulsion that Ek2 shales and mudstones are different in oil generation and expulsion efficiency. Comparing with the mudstones, the shales are lower at low mature stage (Ro<1.0%), but equivalently more than 90%at mature stage (Ro>1.0%). Based on hydrocarbon generation mechanism study of saline or semi-saline lacustrine source rocks, two stages of hydrocarbon generation is classified, and one is immature-lower mature oil generation stage, and the other is thermal kerogen degradation stage. It is indicated that the shales are strong in hydrocarbon generation but weaker in expulsion at the early stage. Both shales and mudstones, however, are potential in immature-lower mature oil. This paper re-evaluates the resource potential of Kongnan area and shows that it has the resource potential of immature oil. Thus, the resource of the target area is substantially increased. In the end, this paper takes Kongnan buried hill tectonic belt, Cangshi nose like structure and Xiaoji-Wumaying tectonic belt as future exploration targets.