Influence of Working Fluids on Coalbed Methane Desorption Capacity and Diffusibility

Gas migration includes desorption, diffusion, and seepage processes. Desorption and seepage are the key processes for coalbed methane extraction. Study of the influence of working fluids on coalbed methane desorption and diffusion capacity is important for developing coal beds. The influence of working fluids on coalbed methane desorption was studied using test samples of coal from Qinshui Basin by employing analytical and experimental equipment developed by the authors of the present work. The experimental results indicate that a 0.5% microemulsion in the working fluid has the greatest impact on coalbed methane desorption capacity, providing for a degree of desorption of 65%, and anionic surfactants have the smallest impact on coalbed methane desorption capacity. Introduction of a working fluid into the coalbed causes water blockage and siltation thereby reducing desorption and diffusion process efficiency. To enhance coalbed methane deliverability, it is advisable to minimize the use of working fluids prone to cause great damage during fracturing operation.