RESEARCH ON DIFFERENT ACUMULATION CHRACTER OF GAS POOL FOR THE FIRST MEMBER OF SHAXIMIAO FORMATION IN THE DATACHANG AREA OF SOUTH SICHUAN
For the obvious selective accumulation characteristics of shallow low-pressure gas reservoir of Datachang in the south of Sichuan,the use of oil and gas accumulation of secondary migration theory is used to analyze the low-pressure gas reservoir of Shaximiao Formation in this area.The differences in oil and gas accumulation in the layer section are controlled by structures,reservoir properties,migration pathways,blocking conditions,which formed a combination of factors and the matching conditions.The accumulation of oil and gas possesses following characters:① Main channel sand body in the high part of structure connects with boundary faults at depth.② Sand body of main river channel sedimentation pinch out upwards with well developed small faults and fissures under the sand bodies.③ Stacked channel sand bodies lie in the channel of oil and gas migration.It is thought that the formation and accumulation of gas and oil in the first Member of Shaximiao Formation were controlled by structures,physical property of reservoir,migration channel and shelter conditions.