INSAR IDENTIFIES SUBSIDENCE RESULTING FROM COALBED METHANE PRODUCTION IN THE SAN JUAN BASIN, COLORADO AND NEW MEXICO

Methane produced from buried coal seams, often called coalbed methane or CBM, is methane that is adsorbed into the solid matrix of coal. It is extracted through the production of large volumes of water from methane bearing coal seams. This leads to a reduction of pore pressure within coal seams leading to the liberation of the methane which can subsequently be produced. One concern stemming from this production method is the potential for subsidence resulting from groundwater withdrawal. Past modeled estimates of subsidence have been minimal and thus have been ignored as a potential negative ramification of CBM production.

Since the late 1980’s, methane has been produced from coal beds, predominantly in the Fruitland Formation, within the San Juan Basin of Colorado and New Mexico. Historically, the San Juan Basin has been the largest producer of CBM in North America, and remains the top producing basin today. This study utilizes Interferometric Synthetic Aperture Radar (InSAR) to quantify the surface response to aquifer depletion in the vicinity of CBM production in the San Juan Basin. Results show that there has been enough groundwater production to result in measurable (several cm) subsidence above the CBM fields. Estimates of both magnitude and aerial extent of the subsidence features resulting from CBM production in the San Juan Basin are presented.