THE IMPACT OF PERMEABILITY AND WELL SPACING ON WELL PRODUCTIVITY IN A COALBED METHANE RESERVOIR

The production mechanism of gas from coalbed methane (CBM) reservoir is considered as complex and difficult to analyze. The gas is adsorbed in inner surface of the coal matrix (seam) and usually contain water its fracture. In CBM reservoir, permeability and well spacing are parameters affecting the response of coal-seams reservoirs. Higher permeability will increase fluid flow in coal cleat (fracture), while smaller well spacing may increase the pressure decline of the reservoir. The two phenomena accelerate the gas desorption time from the coal-seams. This paper presents a simulation experiment, intended to study the impact of permeability on gas and water production in coalbed methane reservoir. The results show that the permeability have a significant effect on initial water rate, cumulative gas and water produced. While the well spacing has no effect on initial rate and a little effect on peak gas rate.