New pressure-transient analysis of fractured well for coalbed methane

Coalbed methane is mostly adsorbed in the matrix of coal seam. The process for extracting coalbed methane from matrix of coal seam to the well is pressure reducing-desorption-diffusion-flowing, which is much more complicated than that of extracting conventional gas. Most coalbed methane reservoirs in China are primarily low permeable to very low permeable and do not produce water. In China, recovery of coalbed methane can only be achieved through fracturing, so the testing of fractured well for coalbed methane is very important. In this paper, the single-phase flow of coalbed methane in coal matrix and cleats is studied using non-equilibrium isotherm adsorption model. The effect fracture face damage skin factor on pressure-transient performance and the effects of six parameters on pressure-transient performance are also considered in the new mode.