Origin and distribution of mud diapirs in the Yinggehai basin and their relation to the migration and accumulation of natural gas

Abstract：Mud diapirs are characteristic anomalous seismic-geologic bodies in the Yinggehai basin on the northern margin of the South China Sea and have the less compact, abnormally high-pressure and -temperature and low-density and -velocity geophysical characteristics. They show pronounced zoning and are distributed en echelon in a nearly N-S direction along the northwest trend of the basin. The origin and distribution of the mud diapirs were controlled mainly by the combined action of the great abnormally high-temperature and -pressure potential energy produced by rapid subsidence of the basin and inequilibrium between the filling-compaction of rapidly deposited sediments and fluids squeezed out and the dextral strike-slip extension of regional basin-controlling faults in the late stage. The natural gas and CO2 migration and accumulation were effectively controlled by the effective combination of the upward intrusion of the late-stage mud-diapir thermal fluids and their accumulation conditions.