San Juan Basin Coal-bed Methane Well Completion Techniques

MAVOR, MATT, Resource Enterprises, Inc., Salt Lake City, UT

Coal-bed methane wells in the San Juan basin Fruitland Formation are typically completed by running and cementing casing through the coal interval followed by jet perforation and hydraulic fracture stimulation. Completion design has a significant effect upon productivity, as illustrated by open-hole cavity completions that are producing significantly greater coal-bed methane gas rates than cased and fractured wells. Cavity completions are installed by top-setting overpressured, relatively high-permeability coal seams with casing and drilling through the coal with formation water. Once total depth is reached, air is injected to increase the well pressure, followed by a rapid blowdown to allow coal, water, sand, and shale to collapse into the well and be produced. This presentation summ rizes these fractured and cavity well completion techniques and quantifies reasons for the productivity differences.

Quantitative analyses concerning the effectiveness of hydraulic fracture stimulations will be presented. The quantitative data and information to be presented on cavity completions have been obtained from the Completion Optimization and Assessment Laboratory (COAL) site located 23 mi southwest of Durango, Colorado. The COAL site is a joint research effort between Amoco Production Company, the Gas Research Institute (GRI), and Resource Enterprises, Inc., to quantify open-hole cavity completion behavior. Sufficient information has been collected from this site to evaluate the reservoir properties and geology, the geometry of the induced cavity, and the effect of the cavity upon coal properties and fluid deliverability. This presentation will be the first time that the data have been dis ussed publicly.

AAPG Search and Discovery Article #91010©1991 AAPG Rocky Mountain Section Meeting, Billings, Montana, July 28-31, 1991 (2009)