Productivity control factors and extraction practice of coalbed methane horizontal well

Abstract：To demonstrate the productivity control factors in coalbed methane （CBM） horizontal wells, based on the method of theoretical analyses, the factors, such as critical desorption pressure, gas saturation and permeability which control CBM horizontal wells＇ productivity were analyzed. Three stages bottom hole pressure （BHP） control method were put forward, the first stage is BHP greater than critical desorption pressure, the second stage is BHP less than critical desorption pressure but greater than 0. 5 times critical desorption pressure, and the third stage is BHP less than 0. 5 times critical desorption pressure. Bottom hole pressure control according to the following principles：the first stage to implement the formation fluid supply capacity,liquid descending amplitude less than 3 m/d;the second stage to implementation of coalbed methane well gas production capacity slowly, liquid descending amplitude 1 m/d;the third stage with stable production, maintenance of bottom hole pressure, when gas production rate decline should descending liquid amplitude 0. 5 m/d. The field application results demonstrate three stages BHP control method can reduce regional pressure, and full improve the CBM well productivity.