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Analytical solutions of fractal-hydro-thermal model for two-phase flow in thermal stimulation enhanced coalbed methane recovery

ABSTRACT
Thermal stimulation is a useful supplementary mining technique for the enhancement of coalbed methane (CBM) recovery. This technique couples the temperature change with gas-water two-phase flow in the mining process. Many integer dimension hydro-thermal models have been proposed but cannot well describe this coupling because two-phase flow and heat conduction are usually non-linear, tortuous and fractal. In this study, a fractal-hydro-thermal coupling model is proposed to describe the coupling between heat conduction and two-phase flow behaviors in terms of fractional time and space derivatives. This model is analytically solved through the fractal travelling-wave method for pore pressure and production rate of gas and water. The analytical solutions are compared with the in-situ CBM production rate. Results show that our proposed fractal-hydro-thermal model can describe both heat and mass transfers in thermal stimulation enhanced CBM recovery.
KEYWORDS
PAPER SUBMITTED: 2018-06-20
PAPER REVISED: 2018-09-10
PAPER ACCEPTED: 2018-11-15
PUBLISHED ONLINE: 2019-04-14
DOI REFERENCE: https://doi.org/10.2298/TSCI180620132S
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