FORMATION CONDITIONS AND INTERNAL FEATURES OF DEEP BASIN GAS ACCUMULATIONS

Deep basin gas accumulation (DBGA) has been followed with wind interests by petroleum geologists since the being put forward of the concept DBGA (deep basin gas trap by J. A. Masters)and the breakthrough of accumulation mechanism,especially its enormous reserves. Deep basin gas accumulations are distinct from normal ones in origin mechanism,genetic features and distribution rules. The formation and distribution of DBGAs are restricted by tight sand reservoirs with low porosity,low permeability and high saturation of water. The fundamental features of DBGAs are the overturning of formation fluids and occurring of abnormal pressures. DBGAs are distinguished from normal ones in their basic principles,general characteristics and genetic sequences. DBGA is discussed thoroughly in the paper to expect to be useful for the exploration of DBGA in China.