Influence of High-rank Coal Reservoir Sensitivity on Coalbed Methane Wells Production

In order to realize the efficient exploitation of coalbed methane in high- rank coal reservoir,the velocity sensitivity and stress sensitivity of Sihe No. 3 coal seam were experimented and analyzed. Based on the engineering,the influence of high- rank coal reservoir sensitivity on coalbed methane wells production was analyzed. The experimental results showed that,high- rank coal reservoir had the feature of velocity sensitivity,the permeability could reduce to 50% of initial value to the maximum extent,directional flooding would also reduce permeability,the minimum reduce to 62. 1% of initial value,the higher the clay content of the reservoir was,the lower the permeability decreasing amplitude would be. The high- rank coal reservoir had a strong stress sensitivity and existed apparent irreversibility; when the net confining pressure increased from 2 MPa to 5 MPa,the permeability decreased as 20% ~ 50% of the initial permeability,after the buck boost,the permeability could not resume to the initial level,the maximum of irreversible damage rate was more than 50%,the lower the reservoir permeability was,the stronger the stress sensitivity would be. The coalbed methane wells production process should follow continuous,slow and stable principle,especially in initial stage.