Research On Coupling Theory Of Horizontal Borehole And Coalbed Methane Reservoir

A pinnate horizontal well mathematics model was given in coalbed methane reservoir, considered the coupling of well bore and reservoir. The model based on the coupling theory of horizontal well in oil reservoir and the storage migration mechanisms of coalbed methane. Besides, a corresponding reservoir simulator was developed. The major study of this paper includes:(1) A three-dimensional, dual-porosity, pseudo-steady, non-equilibrium sorption, two-phase mathematical model was built, included complex processes of desorption, diffusion and seepage during the exploiting procedure of coalbed methane. The model was numerical solved with IMPES method. And the result was compared with CMG software's.(2) Both horizontal well and pinnate horizontal well mathematics models were built in coalbed methane reservoir, considered the coupling of well bore and reservoir. The models were solved by numerical difference method. And the effect of simulation parameters to gas production was studied, with the emphasis on the branch number and angle.(3) Based on the character of low permeability coalbed methane reservoir, a two-phase, 3-D flow model considering the starting pressure gradient of dual-porosity media was established. The model was solved by numerical difference method. And the effect of gas phase's starting pressure gradient to gas and water production was studied.