The Yingqiong Basin is a Cenozoic high-temperature and high-pressure basin with rapid subsidence

usually accompanied by the development of thermal fluid diapirs.This formed a unique hydrocarbon migration system

with the diapirs and fractures caused by the pressure release of deep strata functioning as the major transporting pathways of natural gas in the basin.The research distinguished 2 types of migration systems in the Yingqiong Basin:the high-pressure-diapir system and the fracture system

based on 3D seismic coherence analysis and curvature analysis along the formation.The spatial distribution characteristics of these two systems and their evolution processes have been investigated

and the relationship between the overpressured migration systems and the gas charging

dissipating and accumulating in the study area is analyzed by geochemical means such as natural gas isotopes and inclusions.The results indicate that

in spatial distribution

the two types of migration systems are characterized by stepwise development from deep to shallow:the former usually develops in the central depression zone of the Yinggehai Basin and the latter mainly distributes in the margin of thermal fluid diapirs and the high-pressure strata in the subsidence center proximity part of the steep slopes.According to the evolution history

the diaper migration system consists of five stages (types):pressurization

puncture

equilibrium

release and collapse

and at each stage the gas accumulation style features deep gas charging

shallow gas accumulating

simultaneous deep and shallow accumulating

flank accumulating

and accumulation destruction respectively.The fracture migration system originates from either high pressure or certain deformation processes

characterized with early gas accumulation in shallow strata and later gas accumulation in deep ones.