Study On Dynamic Characteristics Of Horizontal Well Pressure And Yield In Shale Gas Reservoir

As an un-conventional energy, shale gas has widely concerned by the global societies because of its enormous geological reserves. Meanwhile, the exploration and development of shale gas also attaches more attention in our country. Shale gas reservoirs are obviously different from the conventional ones because of its unique characteristics on geological properties, gas storage methods and the micro migration law. At present, the pressure dynamic analysis model and production rate decline model for shale gas wells are mostly based on the conventional dual porosity flow model, which usually ignores the process of adsorption diffusion. In this paper, a transient seepage mathematical model considering the features of shale gas reservoir is established, and obtained the continuous point source solution by applying some corresponding mathematical methods. Based on the seepage flow model, attaining the shale gas horizontal well’s and multiple-fractured horizontal one’s pressure dynamic model and production decline model, which can provide an important theoretical basis for the development of shale gas reservoirs. Four main results and understanding through research are getting in this paper:(1) Finding shales belong to low porosity and low permeability tight gas reservoir, and the storage of shale gas is related to the internal and external environment, and the diffusion processes of desorbed gas on the micro pore wall surface diffusing to the matrix pores is different from the free gas diffusing in the matrix pores.(2) Attaining the shale gas horizontal well pressure dynamic analysis model and production decline model by combining with the boundary conditions, and obtained the continuous point source solution by utilizing some corresponding mathematical methods. Then drewing the type curves of dimensionless pseudo-pressure and dimensionless production for a horizontal well in shale gas reservoir, and analysis some sensitive parameters for the pressure dynamic and production decline.(3) Attaining the shale gas multi-stage fractured horizontal well pressure dynamic analysis model and production decline model based on shale gas horizontal well model, and drewing the type curves of dimensionless pseudo-pressure and dimensionless production for a multi-stage fractured horizontal well in shale gas reservoir. Then analyze some sensitive parameters for the pressure dynamic behaviors and production decline properties.(4) By comparing the dynamic pressure distribution and the trend of production decline before and after hydraulic fracturing, the result shows that the type curves of dimensionless pseudo-pressure and dimensionless production tend to have a same trend. But the growth rate of dimensionless pseudo-pressure becomes smaller and the decline rate of dimensionless production becomes slower after hydraulic fracturing.