Formation processes of gas condensate reservoirs in the Baiyun Depression: Insights from geochemical analyses and basin modeling

The petroleum phase in a petroleum reservoir and the formation process of gas condensate reservoirs became a hotspot in petroleum geoscience. This study recovered the petroleum migration processes in the western sag of the Baiyun Depression based on the geochemical analyses and basin modeling to illustrate the formation processes of gas condensate reservoirs in the Baiyun Depression. The geochemical parameters of light oil and natural gases indicated that they originated from the Enping Formation. Basin modeling indicated that the Enping source rocks in the western sag were mature after 13.8 Ma. The petroleum migrations in the Enping and Zhuhai Formations were vertical, and the lateral migration occurred in the Lower Zhujiang Member. The petroleum generation–migration and temperature–pressure conditions mostly controlled the petroleum phase. The Enping source rocks produced some amount of oil in the oil window and generated considerable amount of gas later. Continuous gas charging increased the gas–oil ratio, and the light oil dissolved in the gas. With the increase in temperature and pressure, the oil reservoir eventually turned into a gas condensate reservoir. The gas condensate reservoir formation was mainly related to petroleum generation–migration–accumulation processes in the western sag. This study could contribute to petroleum exploration and development in the Baiyun Depression and some similar basins.