Analysis on occurrence state of deep coalbed methane in Junggar basin

A relatively high gas production rate has been obtained through the tests on deep coalbed methane in Baijiahai uplift in the hinterland of Junggar Basin.Through the analysis on CBM production tests in Baijiahai area and combined with such analytical chemical tests as coal core gas content, isothermal adsorption and coal petrology, it is determined that the occurrence state of deep coalbed methane in Junggar Basin is mainly free gas, followed by adsorbed gas.It is found out that the amount of free gas accounts for 53.9% of the total gas.By conducting the inverse of isothermal adsorption curves, flat desorption curve is obtained, and the desorption of adsorbed gas is very difficult.Methane adsorbed is only 3-4 m³ with 12 MPa decompression and drainage.On this basis, a new idea for the deep CBM exploration in Junggar Basin is put forward combining CBM and conventional gas organically mainly for free gas, followed by adsorbed gas.