Heat Flow Action and Its Control on Natural Gas Migration and Accumulation in Mud-Fluid Diapir Areas in Yinggehai Basin

The Yinggehai basin is a young but high geotemperature basin that was developed in the Cenozoic at the northern continental margin of South China Sea. Its high geotemperature and heat flow fields are mainly located in the mud-fluid diapir structure areas in the center of the basin. The development and evolution of the mud-fluid diapir, especially the upwelling of heat flow in the Late Pliocene, is closely related with the migration and accumulation of natural gas and carbon dioxide. The local invasion of heat flow, whose distribution is inhomogeneous in different zones and formations, leads to the migration and accumulation of hydrocarbon and carbon dioxide sourced from crust and mantle to hold the same characteristics. While the upwelling of heat flow in mud-fluid diapir areas is the main factor that influences the migration, accumulation and reservoir formation of hydrocarbon gas, especially carbon dioxide. The time and paths of migration and accumulation differences between crust-sourced and mantle-sourced non-hydrocarbon gas and hydrocarbon gas are the keys to the accumulation and reservoirs formation. Based on the geochemical characteristics and migration and accumulation features of non-hydrocarbon and hydrocarbon gas, we can study and predict the model of their migration and accumulation to provide the references for natural gas exploration.