Experimental study on the effect of salinity on coalbed methane desorption-diffusion

Coalbed methane occurs mainly as adsorbed state in the cleat and matrix pores of the coal. To study the effect of liquids with different salinity on methane desorption-diffusion process, crushed coal particles of seam 3 from Sihe mine were selected as test samples to conduct desorption test after injecting 3 liquids of different salinity into the samples. The results show that all the initial desorption pressure is close to 1.4 MPa, the desorption rate, and early desorption amount are less than 30% of the total amount of desorption, mainly concentrated in late desorption, recovery rate and the initial desorption pressure of source water and formation water are lower than those of the distilled water, and with fluid salinity increase, the desoption rates and recovery rates are slightly reduced.