Geosphere in Underground Coal Gasification

Daniel J. Daly, Gerald H. Groenewold, Craig R. Schmit, James M. Evans

The feasibility of underground coal gasification (UCG), the in-situ conversion of coal to natural gas, has been demonstrated through 28 tests in the United States alone, mainly in low-rank coals, since the early 1970s. Further, UCG is currently entering the commercial phase in the United States with a planned facility in Wyoming for the production of ammonia-urea from UCG-generated natural gas. Although the UCG process both affects and is affected by the natural setting, the majority of the test efforts have historically been focused on characterizing those aspects of the natural setting with the potential to affect the burn. With the advent of environmental legislation, this focus broadened to include the potential impacts of the process on the environment (e.g., subside ce, degradation of ground water quality). Experience to date has resulted in the growing recognition that consideration of the geosphere is fundamental to the design of efficient, economical, and environmentally acceptable UCG facilities. The ongoing RM-1 test program near Hanna, Wyoming, sponsored by the U.S. Department of Energy and an industry consortium led by the Gas Research Institute, reflects this growing awareness through a multidisciplinary research effort, involving geoscientists and engineers, which includes (1) detailed geological site characterization, (2) geotechnical, hydrogeological, and geochemical characterization and predictive modeling, and (3) a strategy for ground water protection.

Continued progress toward commercialization of the UCG process requires the integration of geological and process-test information in order to identify and address the potentially adverse environmental ramifications of the process, while identifying and using site characteristics that have the potential to benefit the process and minimize adverse impacts.

AAPG Search and Discovery Article #91033©1988 AAPG Rocky Mountain Section, Bismarck, North Dakota, 21-24 August 1988