In order to understand production decline law of fractured-vuggy carbonate gas reservoirs more accurate-ly,Blasingame production decline models for triple-porosity single-permeability and triple-porosity dual-permeabili-ty of deviated wells are established assuming that top and bottom boundaries of gas reservoirs and outer boundaries are closed,and reservoir thickness is horizontally uniform.Models are solved by mathematical method of Laplace transformation to obtain bottom hole pressure solution,which is substituted into conversion equation to obtain pro-duction declination solution,and then obtain production solution in real space through numerical inversion.Blasin-game production decline curves of deviated wells with triple-porosity single-permeability and triple-porosity dual-permeability are plotted and compared,and parameters sensitivity is analyzed for production decline curves of devi-ated wells with triple-porosity dual-permeability.The results show that the position of production decline curve of tri-ple-porosity dual-permeability is lower than that of single-permeability in initial stage,with shallower interporosity flow concave.The higher the fracture permeability ratio is,the deeper the interporosity flow concave is,and the low-er the curve position is.The larger the interporosity flow coefficient is,the earlier the interporosity flow occurs,with curve position shifting leftward.The higher the elastic storativity ratio of matrix is,the wider and deeper the interpo-rosity flow concave of matrix-to-fracture is,and the narrower and shallower the interporosity flow concave of vug-to-fracture is.The longer the well length and the larger the deviation angle of deviated well are,the higher the position of production decline curve is,with curve shifting leftward.Combined with field case well interpretation,triple-po-rosity dual-permeability model of deviated well has better fitting effect and more reliable interpretation result than triple-porosity single-permeability model.Established single-permeability and dual-permeability models and plotted Blasingame production decline curves can predict production decline law of deviated wells in carbonate gas reser-voirs.
关键词
碳酸盐岩气藏/斜井/双渗/Blasingame产量递减曲线/敏感性分析
Key words
carbonate gas reservoirs/deviated well/dual-permeability/Blasingame production decline curve/sensitivity analysis
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