关键词: 川中地区, 上三叠统, 须四段, 砂体成因, 河道砂体, 油气运移通道

Abstract: The sand body in the forth member of Xujiahe Formation of Upper Triassic in the central Sichuan Basin has the features of large thickness and continuous sedimentation,where sedimentary facies belongs to deltaic deposit in the proximity of source area.There are different accommodation space and sedimentary supply in the sediment stage.The sand body in the forth member of Xujiahe Formation consists of three vertical superposed types of the regressive model,channel model and transgress model from bottom to top.The channel sand body has the best physical property.The interface between channel sand body and regressive sand body is unconformity and thus shows the mosaic relation,which is favorable for natural gas migration.In addition,the channel sand body is characterized by wide-ranging distribution and high-porosity and can provide the sufficient space for oil-gas enrichment.The reservoirs in the transgress sand body on the top become tight and turn into favorable cap rock,which promotes the channel sand body becoming the favorable position of oil-gas enrichment in the central Sichuan Basin.

Key words: central Sichuan Basin, Upper Triassic, the forth member of Xujiahe Formation, sand body genesis, channel sand body, oil-gas migration pathway