Application of geological studies to overburden collapse at underground coal gasification experiments

Conference · Mon Aug 01 04:00:00 EDT 1983 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6435666

Ethridge, F G; Alexander, W G; Craig, II, G N; Burns, L K; Youngberg, A D

Detailed geologic and mineralogic studies were conducted on the Hanna, Wyoming, and Hoe Creek, Wyoming, underground coal gasification sites. These studies demonstrate the importance geologic factors have on controlling overburden collapse into the reactor cavity during and after coal gasification and on subsequent environmental problems. Parameters that control the collapse of overburden material into the reactor cavity include: duration of the burn; maximum span of unsupported roof rock; lateral and vertical homogeneity, permeability and rock strength; and thickness of overburden materials. At the Hoe Creek I experiment, a small reactor cavity and a correspondingly short maximum span of unsupported roof rock consisting of fine-grained, low permeability overbank deposits resulted in minimal collapse. At the Hoe Creek II experiment, a significant amount of collapse occurred due to an increased span of unsupported roof rock comprised of poorly consolidated, more permeable channel sandstones and a limited amount of overburden mudstones and siltstones. Roof rock collapse extended to the surface at the Hoe Creek III experiment where the roof rock consisted of highly permeable, poorly consolidated channel sandstones. The unit comprising the reactor cavity roof rock at the Hanna II experimental site is a laterally continuous lacustrine delta deposit, which primarily consists of sandstones with lesser amounts of interbedded siltstones and claystones. Calcite cement has reduced permeability and interstitial waters which probably kept spalling of the roof rock to a minimum. Consequently, roof rock collapse at the Hanna II experiment was much less extensive than at the Hoe Creek II and III experiments.

• Research Organization: Colorado State Univ., Ft. Collins
• OSTI ID: 6435666
• Report Number(s): CONF-8309274-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 67:8
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
COAL DEPOSITS
COAL GASIFICATION
ENVIRONMENTAL EFFECTS
FEDERAL REGION VIII
GASIFICATION
GEOLOGIC DEPOSITS
IN-SITU GASIFICATION
IN-SITU PROCESSING
MECHANICS
MINERAL RESOURCES
NORTH AMERICA
OVERBURDEN
PROCESSING
RESOURCES
ROCK MECHANICS
ROOFS
STABILITY
THERMOCHEMICAL PROCESSES
USA
WYOMING