Role of site characteristics in the control of underground coal gasification
Underground Coal Gasification (UCG) offers many potential economic and environmental advantages. Offsetting these advantages is the substantial lack of ability to control the UCG process. For example, only three elements of external process control have been utilized. These are: (1) injected gas composition, (2) injected gas flow rate, and (3) product gas pressure. Variation of these independent variables in UCG tests has resulted in mixed indications of their effectiveness. This study indicates other possible elements of control based on the results of recent field tests and modeling efforts. These elements are associated with the selection of the specific site where the process is conducted and with the design of the test itself. The results of previous UCG field tests have indicated that the conditions that exist in the coal seam and overburden before the start of the combustion process may dominate all other factors. These conditions are the geotechnical characteristics, such as faulting and groundwater hydrology, as well as the details of the test layout, well completions, and linking method. Evidence exists to support the thesis that these preignition conditions can be dominant factors in process control of in-situ operations. The data from recent UCG tests have been analyzed with respect to the effect of the site geotechnical characteristics and the test design. The results of this analysis indicate that geologic faulting, coal seam permeability distributions, well completions, and coal strength are important elements of control in the process behavior. Attempts to influence Hanna IVB by varying external process parameters could not overcome these effects. Similar results have been observed in other UCG tests.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6529477
- Report Number(s):
- SAND-80-2664C; CONF-810607-7; ON: DE81023305
- Country of Publication:
- United States
- Language:
- English
Similar Records
Results of the fourth Hanna field test
Overburden characterization and post-burn study of the Hanna IV, underground coal gasification site, Wyoming, and comparison to other Wyoming UCG sites
Related Subjects
010404* -- Coal
Lignite
& Peat-- Gasification
BOREHOLE LINKING
COAL DEPOSITS
COAL GASIFICATION
COAL SEAMS
CONTROL
FIELD TESTS
FLOW RATE
GASIFICATION
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC STRUCTURES
GEOLOGY
IN-SITU GASIFICATION
IN-SITU PROCESSING
MATHEMATICAL MODELS
MINERAL RESOURCES
PERMEABILITY
PRESSURE CONTROL
PROCESS CONTROL
PROCESSING
RESOURCES
TESTING
THERMOCHEMICAL PROCESSES
WELL COMPLETION
WELL SPACING