Spalling and the development of a hydraulic fracturing strategy for coal. Final report, January 1987-February 1991

Technical Report · Mon Apr 01 00:00:00 EST 1991

OSTI ID:5737468

Khodaverdian, M; McLennan, J D; Jones, A H

For commercial development of a large fraction of the United States' coal gas reservoirs, it is important to induce long, highly conductive hydraulic fractures, which intersect the coal seams. To date, high treatment pressures are often observed, resulting in screenout, inadequate length and sometimes out-of-zone growth. Many mechanisms have been proposed to rationalize high treatment pressures. These include poroelasticity, complex fracture geometries and systems, coal spalling, tip plugging, and wellbore failure. Two different approaches were used for identification of high treatment pressure mechanisms in coal. These were laboratory hydraulic fracturing experimentation and post-shut-in pressure decline analysis of field data. The first approach involved hydraulic fracturing of 11 in. {times} 11 in. {times} 15 in. coal blocks under various saturation conditions and far-field stresses. The second approach involved analysis of post-shut-in pressure decline curves for several stimulation records in COMPAS-II database. The conclusions arrived at from two approaches suggest that restricted entry at or near the wellbore is a major cause of high treatment pressures in coal. The laboratory tests further identified two major mechanisms as the causes of the near-wellbore constriction. These are: (1) plugging of the fracture at or near the wellbore, and (2) pore (cleat) pressure buildup around the wellbore.

• Research Organization: Terra Tek, Inc., Salt Lake City, UT (United States)
• OSTI ID: 5737468
• Report Number(s): PB-92-132968/XAB; TR-91-111; CNN: GRI-5087-214-1460
• Resource Relation: Other Information: See also PB91-159517. Sponsored by Gas Research Inst., Chicago, IL
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
01 COAL, LIGNITE, AND PEAT
COAL SEAMS
HYDRAULIC FRACTURING
METHANE
MATERIALS RECOVERY
BENCH-SCALE EXPERIMENTS
COAL DEPOSITS
COAL MINING
COMPUTERIZED SIMULATION
FRACTURE MECHANICS
FRACTURE PROPERTIES
FRAGMENTATION
HYDRAULIC FRACTURES
MECHANICAL PROPERTIES
PLUGGING
PORE PRESSURE
PRESSURIZATION
ROCK MECHANICS
TEST FACILITIES
ALKANES
FAILURES
FRACTURES
FRACTURING
GEOLOGIC DEPOSITS
HYDROCARBONS
MANAGEMENT
MECHANICS
MINERAL RESOURCES
MINING
ORGANIC COMPOUNDS
PROCESSING
RECOVERY
RESOURCES
SIMULATION
WASTE MANAGEMENT
WASTE PROCESSING
030300* - Natural Gas- Drilling
Production
& Processing
012033 - Coal
Lignite
& Peat- Underground Mining- Mine Environment- (1987-)