STUDY ON THE NATURAL GAS ACCUMULATION MODELS AND STRUCTURE OF THE YINGGEHAI BASIN

The Yinggehai Basin was developed on the base of the seaward extended part of the Red River Rift zone controlled by the double mechanisms of mantle-uplift extension and strike slipping along the Red River Rift.It has rift-depression dual structure.The evolution of the Yinggehai Basin has experinced rift and depression formation two stages.During different evolutionary stages,thermal subsidence and the Red River rifting played different parts.The Yinggehai Basin has the central diapir zone and the Yingdong slope zone two natural gas accumulation models.The activities of diapir heat flow provided accumulation places and dynamic conditions for the accumulation of natural gas in the central of the basin,and the natural gas in high-pressure compartments released upward many times by the way of outpouring flowing and then accumulated.On the other hand,the natural gas pools in the Yingdong slope zone were the results of natural gas generated in the deep part of the basin migrated to the slope zone driven by solution convection mechanism and then accumulated in reservoir-cap well-matched positions.