Abstract

CHEN, Wangang et al. Solution and type curves for the seepage model of the water-bearing coalbed with leakage recharge. Earth Sci. Res. J. [online]. 2017, vol.21, n.1, pp.17-21. ISSN 1794-6190.  https://doi.org/10.15446/esrj.v21n1.63003.

To analyze the effects of the leakage recharge of the aquifer on the initial dewatering of coalbed methane wells, the mathematical seepage model of water in the coalbed considering the aquifer leakage was established by using the leakage coefficient according to the unsteady seepage theory. The model was solved after Laplace transform and the Stehfest numerical reverse inversion was used to obtain the solution in right space. Then, the log-log type curves of pressure and pressure derivative were created with new combinations of parameters. Based on the natural seepage mechanism, the influence of aquifer leakage on curve shape was judged. It is found that the radial flow ends earlier as the leakage coefficient increases. Moreover, it was proposed to obtain reservoir permeability, skin factor, and leakage coefficient by using type curve matching. The type curves are useful for quantitatively evaluating the level of leakage, thereby guiding the adjustment of the following production system for CBM wells.

Keywords : Coalbed methane (CBM); Formation water; Leakage; Well test analysis.

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