Integrated exploration strategy for locating areas capable of high gas rate cavity completion in coalbed methane reservoirs
In 1993, the San Juan Basin accounted for approximately 605 Bcf of the 740 Bcf of all coalbed gas produced in the United States. The San Juan {open_quotes}cavitation fairway{close_quotes} in which production occurs in open-hole cavity completions, is responsible for over 60% of all U.S. coalbed methane production. Perhaps most striking is the fact that over 17,000 wells had penetrated the Fruitland formation in the San Juan Basin prior to recognition of the coalbed methan potential. To understand the dynamic cavity fairway reservoir in the San Juan Basin, an exploration rationale for coalbed methan was developed that permits a sequential reduction in total basin exploration area based on four primary exploration criteria. One of the most significant criterion is the existence of thick, thermally mature, friable coals. A second criterion is the existence of fully gas-charged coals. Evaluation of this criterion requires reservoir geochemical data to delineate zones of meteoric influx where breaching has occurred. A third criterion is the presence of adequate reservoir permeability. Natural fracturing in coals is due to cleating and tectonic processes. Because of the general relationship between coal cleating and coal rank, coal cleating intensity can be estimated by analysis of regional coal rank maps. The final criterion is determining whether natural fractures are open or closed. To make this determination, remote sensing imagery interpretation is supported by ancillary data compiled from regional tectonic studies. Application of these four criteria to the San Juan Basin in a heuristic, stepwise process resulted in an overall 94% reduction in total basin exploration area. Application of the first criterion reduced the total basin exploration area by 80%. Application of the second criterion further winnows this area by an addition 9%. Application of the third criterion reduces the exploration area to 6% of the total original exploration area.
- Research Organization:
- Alabama Univ., University, AL (United States); Gas Research Inst., Chicago, IL (United States); Environmental Protection Agency, Washington, DC (United States); Mine Safety and Health Administration, Arlington, VA (United States); Alabama Geological Survey, University, AL (United States); US Department of Energy (USDOE), Washington DC (United States)
- DOE Contract Number:
- FG03-93ER81502
- OSTI ID:
- 106785
- Report Number(s):
- CONF-950572-; ON: DE95014457; TRN: 95:006491-0003
- Resource Relation:
- Conference: Intergas `95: international unconventional gas symposium, Tuscaloosa, AL (United States), 15-19 May 1995; Other Information: PBD: [1995]; Related Information: Is Part Of Intergas `95: International unconventional gas symposium. Proceedings; PB: 576 p.
- Country of Publication:
- United States
- Language:
- English
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