Gas Water Distribution Model and Control Factors in Low Permeability High Water Saturation Sandstone Gas Reservoirs

The complexity of gas water distribution in the low permeability sandstone gas reservoir is decided by the reservoir characteristics of low porosity,low permeability,strong heterogeneity.The complicated structure and collocation of pore throats results in the complexity of gas-water distribution in low permeability high water saturation sandstone gas reservoirs.The reasons for the complicated structure and collocation of pore throats are analyzed thoroughly,and the cause of high water saturation is explained.Combined with the gas-water distribution of the Xujiahe Group reservoir,three gas water distribution models were concluded.Among the three models,the model of gas-water distribution controlled by reservoir unit is the primary one in the areas of plain structure and strong heterogeneity.Then the main factors of controlling gas water distribution were analyzed from macro scale to micro scale,all to part according to the reservoir characteristics of gas water distribution,structure,and heterogeneity: the area structure background dominates the macro distribution of gas water,the reservoir heterogeneity controls the partial distribution,and the space match between pore types and throat structures affect the micro differentiation of gas and water.