The Powder River Basin: Hydrogeology of Coalbed Natural Gas Production
and Airborne Lidar Terrain Mapping

Roberto Gutierrez, principal investigator; John R. Andrews, Alan R. Dutton, Tiffany L. Hepner, and Rebecca C. Smyth; Amy Neuenschwander and John Schutz (The University of Texas at Austin Center for Space Research)

Production of natural gas from coal beds (CBNG) has proved to be a significant addition to U.S. natural gas resources, accounting for about 8 percent of the 2002 production of dry gas. A large percentage of this production comes from the Powder River Basin in Wyoming and Montana. BEG researchers are now working with one of the basin's technology leaders, Marathon Oil Company, to apply their skills in lidar high-resolution topographic mapping to achieve the greatest production having the least surface and environmental impact on the basin.

In May 2002, BEG transported its ALTM 1225 lidar mapping system to the Powder River Basin and conducted hundreds of miles of airborne lidar and ground Global Positioning System (GPS) surveys. Data generated from the surveys were used to construct high-resolution, detailed 3-D maps called digital elevation models (DEM's) that are currently being used to evaluate and plan a multitude of CBNG operations. Project hydrologists are using the DEM's to delineate surface drainage features, design reservoirs and containment ponds, and model water retention and ground recharge to manage produced groundwater. These DEM's have become an excellent tool for project engineers as they plan drilling locations and design roads, surface facilities, and pipelines with minimal environmental impact. Planning results and maps are also used by landmen to communicate with landowners and by surface hydrologists to communicate with government permitting agencies. The value and wide usability of lidar-generated DEM's have made them an indispensable tool for development of CBNG reserves.

By the summer of 2004, BEG had mapped 650 square miles of the Powder River Basin. Working with UT-CSR, we then generated a comprehensive, township-based series of terrain-only and all-points DEM's for the study area. This series of DEM's incorporate all the lidar data collected in 2003 and 2004; they have a 5-ft horizontal resolution and 0.5-ft vertical accuracy. In addition, the lidar point data have been formatted and parsed into 1-mile sections to allow project geologists and engineers to import them easily into CAD software for engineering applications. An important aspect of the 2004 work was the development of adaptive filtering techniques for the classification of lidar point data into terrain and nonterrain categories. These semiautomated filtering algorithms are fast and effective and proved crucial in generation of accurate terrain-only topography. This research is funded by Marathon Oil Company.

 

For more infomation, please contact Jeff Paine. Telephone 512-471-1260; e-mail jeff.paine@beg.utexas.edu.

September 2005