Spatial Variation of San Juan Basin Fruitland Coalbed Methane Pressure Dependent Permeability: Magnitude and Functional Form

The San Juan basin Fruitland coalbed methane (CBM)<br>resource is the most significant CBM play discovered in the<br>world to date and comprises areas within both Colorado and<br>New Mexico of the United States. It contains three distinctly<br>different performance areas within the 6,800 mile2 (17,600<br>km2) enclosed by the Fruitland outcrop. Two of these areas are<br>considered in this topic: “Fairway” and “Colorado Type II”.<br>Explaining well performance in these areas has required the<br>examination of a mechanism whereby coal permeability<br>increases over time. Field data and pressure transient analysis<br>(PTA) for Fairway wells have revealed that coal permeability<br>does increase over time and is an exponential function of<br>reservoir pressure depletion.