Lower limit of porosity-permeability structure of tight sandstone gas reservoir and its influence on gas-water distribution——Taking Su 48 and Su 120 blocks in Sulige gas field as examples

Sulige gas field is a typical tight sandstone gas reservoir. The gas and water distribution characteristics are quite complicated, which have a great impact on productivity in the process of gas reservoir development. The lower limit of pore-throat structure and its influence on gas-water distribution in the study area were analyzed by using the experimental data of casting thin section, high pressure mercury injection and phase permeation. The results show that the fractured pores, intergranular pores and inter-crystalline pores of cuttings are mainly developed in Su 48 block. The pore types in Su120 block are mainly of karst and inter-crystalline. In the study area, the lower limit of movable hole throat is 0.0038μm,the thickness of water film is 0.002μm, and the pore throat radius range affected by capillary water is0.0038～0.0500μm. The characteristics of gas-water distribution are mainly controlled by lithology in macroscopic view, and affected by pore-throat distribution microscopically. The influence of reservoir porosity and permeability on gas-water distribution is complicated.