Migration models of pulverized coal flowing with fluid and its production in CBM channels for the coal reservoirs

The mathematical models of fluid mechanism in porous medium was developed based on the two phase liq- uid+ solid flow theory. Then the pulverized coal migration flowing with fluid was established for coalbed methane (CBM) channels in coal reservoirs. The pressure and velocity of fluid flow and coal concentration were given out based on numerical solution. The results show that the maximum coal concentration results with high fluid flow rate are near wellbore. The coal production in CBM channels is high due to the high water flow rate and pressure drop during the initial production. However,it is low resulted with the reduced water production and pressure drop between coal reservoir and bottom hole during the resistant period. The maximum coal concentration increases from 0. 112% up to 0. 608% when pressure drop is from 2. 05 MPa to 3. 05 MPa. And the enhanced diameters of CBM channels are bene- ficial to the decrease of coal concentration. The increased diameter of channel from 0. 30 mm up to 0. 90 mm leads to the decreased coal concentration from 0. 759% to 0. 160% . The pulverized coal migration flowing with fluid is predicted accurately in CBM channels,which will provide the reasonable basis for calculating coal production and designing coal control.