Spalling and the development of a hydraulic-fracturing strategy for coal. Annual report, October 1989-September 1990
Laboratory hydraulic fracturing experiments were performed on coal blocks from a mine near Marion Center, PA, in order to identify the responsible mechanisms for the high treatment pressures in coal. Tests were performed on saturated as well as unsaturated blocks containing lined and unlined wellbores. Wellbore lining would prevent pore pressure buildup around the wellbore; it would also prevent blockage of fracture entrance by coal particles. For some of the blocks, the 'in-fracture' pressures were directly measured by placing horizontal boreholes, instrumented with pressure measuring probes, across the fracture path. Test results have indicated that the high treatment pressures observed are principally near wellbore effects. These include poroelastic effects around the wellbore and plugging of the fracture entrance at or near the wellbore. Furthermore, these tests have shown that the hypothesized mechanisms associated with fracture tip (e.g., tip plugging and collapse) and multiple parallel fracturing are not the primary causes of the high treatment pressures on a laboratory scale.
- Research Organization:
- Terra Tek, Inc., Salt Lake City, UT (USA)
- OSTI ID:
- 5790530
- Report Number(s):
- PB-91-159517/XAB; TR-91-48; CNN: GRI-5087-214-1460
- Resource Relation:
- Other Information: See also PB90-233818. Sponsored by Gas Research Inst., Chicago, IL
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COAL SEAMS
HYDRAULIC FRACTURING
STRESS RELAXATION
BENCH-SCALE EXPERIMENTS
BOREHOLES
COAL
COAL DEPOSITS
COAL MINING
COMPRESSION STRENGTH
ELASTICITY
FRACTURE PROPERTIES
FRACTURING
MECHANICAL PROPERTIES
METHANE
POROSITY
PRESSURE MEASUREMENT
RESERVOIR PRESSURE
ROCK MECHANICS
TEST FACILITIES
WELL CASINGS
ALKANES
CARBONACEOUS MATERIALS
CAVITIES
COMMINUTION
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC DEPOSITS
HYDROCARBONS
MATERIALS
MECHANICS
MINERAL RESOURCES
MINING
ORGANIC COMPOUNDS
RELAXATION
RESOURCES
TENSILE PROPERTIES
012031* - Coal
Lignite
& Peat- Underground Mining- Strata Mechanics & Control- (1987-)