Abstract:

With the adsorption, desorption and seepage of coalbed methane(CBM), coal mass deformation easily leads to coal-gas outburst in the process of production. Taking Tiandiwangpo Mine in Jincheng for example, the experiment of adsorption, desorption and seepage of coalbed methane(CBM) and deformation are simulated under complicated stresses condition. The relationships among pore pressure, desorption quantity and deformation are presented. The relationship expressions are studied. Some novel laws are obtained as follows. (1) At the beginning, desorption quantity increases rapidly over time; then it is stabilized latterly. (2) With the rising of pore pressure, the value of desorption quantity and deformation are increased; the desorption quantity and deformation are in parabolic curve relationship with pore pressure. (3) A minimal pore pressure exists; desorption time will increase with the increasing of pore pressure; the laws of desorption quantity and time will inconsistent when it is smaller than the minimal pore pressure. For the coal sample No.3, the minimal pore pressure is about 1.0 MPa. (4) Desorption quantity and coal mass deformation have a lot to do with loading methods; the result of loading methodⅡ is higher than loading methodⅠabout 13%-77%. The results provide a theoretical basis for security of coalbed methane(CBM) drainage and controlling of coal-gas outburst.

Key words: coalbed methane, desorption, deformation, pore pressure