Well Testing And Well Patterns Optimization Research On Fractured Well In Coalbed Methane Reservoir

Based on the desorption, diffusion and seepage migration mechanisms of coalbed methane, two mathematics models were built in coalbed methane reservoir, considering the seepage migration law of vertically fractured well in reservoir. Besides, the effects of the different factors on inter-well interference were simulated and analyzed in the well network development, using the CBM-sim software. The major results of this paper were as follows:(1) Based on bilinear the above mechanisms of coalbed methane, finite conductivity and flow law, a bilinear flow mathematical model for finite conductivity vertically fractured well in coalbed methane reservoir was built. After the model was transformed by the Laplace transform, it was solved with the Stehfest numerical inversion method. Type curves were plotted. The effects of the various parameters on the dimensionless wellbore pressure were studied.(2)Based on trilinear flow law and the mechanisms of the above model, a trilinear flow mathematical model for finite conductivity vertically fractured well was built. The model was was solved with the Stehfest numerical inversion method. Typical well test curves were plotted by using these numerical results. The effects of the various parameters on the dimensionless wellbore pressure and pressure derivative were analyzed.(3) The effects of the control factors on inter-well interference were simulated and analyzed in the well network development by using the CBM-sim software. The impact of the six different factors on gas production was analyzed. These factors include well spacing, porosity, permeability, gas saturation, fracture penetration ratio and the work system.