MONITORING SURFACE RESPONSE TO COAL BED METHANE PRODUCTION IN THE POWDER RIVER BASIN, WYOMING USING InSAR

Interferometric Synthetic Aperture Radar (InSAR) has been used to document surface displacements resulting from a wide range of anthropogenic and non-anthropogenic causes. InSAR allows for the delineation of such features with a spatial resolution that is orders of magnitude greater than traditional leveling techniques as well as the most rigorous Global Positioning System (GPS) studies. Areas as large as 100 x 100 kilometers can be evaluated with a vertical resolution (representing deformation) of less than 1 cm. One of the more recent applications of InSAR is the evaluation of subsidence resulting from groundwater withdrawal. InSAR has proven an invaluable tool in assessing aquifer system response to groundwater use in the arid west as well as other locations.

This study documents surface deformation resulting from Coal Bed Methane (CBM) production from within the Powder River Basin in Eastern Wyoming. CBM production involves the pumping of large volumes of water (as much as 68,000,000 barrels per month basin wide) in order to liberate methane trapped in buried, saturated, coal seams. This work documents multiple sites within the Powder River Basin where several centimeters of surface subsidence has occurred over areas as large as 200 square kilometers. These results may have implications both to improvements in CBM production as well as regulating water use in the region.