Hydraulic fracturing experiments in Devonian shale and pre-fractured hydrostone. Final report

Technical Report · Wed Sep 30 04:00:00 EDT 1981

OSTI ID:6478899

Blanton, T L

Devonian shale reservoirs in the Appalachian Basin are naturally fractured reservoirs, and constructive interaction with the natural fracture system is critical to the success of any stimulation treatment. To be effective hydraulic fractures should cross and connect the natural fracture system, but it is possible that arrest, diversion, or offset could occur inhibiting fracture growth and proppant placement. The purpose of this study has been to perform laboratory experiments that allow examination of hydraulic fracture propagation in pre-fractured material under triaxial states of stress. Tests have been run on naturally fractured blocks of Devonian shale as well as blocks of hydrostone in which planar fractures have been created. Specific objectives were to (1) qualitatively examine the effect of natural fractures on morphology of hydraulic fractures in Devonian shale and (2) determination under what combination of stresses and angle of approach a hydraulic fracture will cross a pre-existing fracture. In tests on pre-fractured hydrostone the hydraulic fracture was able to cross the pre-fracture only at high angles of approach and under high horizontal differential stresses. In most cases either the pre-fracture opened and fracturing fluid was diverted down the pre-fracture or the hydraulic fracture was arrested by the pre-fracture and continued to grow in the other direction. Tests in Devonian shale blocks showed the strong influence of pre-existing fractures. Diversion of fracturing fluid, fracture arrest, and branching were observed in the hydraulically fractured blocks. The implication of theory and experiment for hydraulic fracturing in the field is that symmetrical, double-winged, vertical fractures are rare occurrences innaturally fractured reservoirs. It would be more likely to have fractures with wings diverted at different angles or with truncated wings of different lengths. 24 figures, 4 tables.

• Research Organization: Department of Energy, Morgantown, WV (USA). Morgantown Energy Technology Center
• DOE Contract Number: AM21-78MC08216
• OSTI ID: 6478899
• Report Number(s): DOE/MC/08216-1331; ON: DE83006486
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030900* -- Natural Gas-- Artificial Stimulation
Plowshare-- (-1989)
58 GEOSCIENCES
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
APPALACHIA
BENCH-SCALE EXPERIMENTS
BITUMINOUS MATERIALS
BLACK SHALES
CARBONACEOUS MATERIALS
CHATTANOOGA FORMATION
COMMINUTION
COMPARATIVE EVALUATIONS
DATA
DEVONIAN PERIOD
DIMENSIONS
ENERGY SOURCES
EXPERIMENTAL DATA
FAILURES
FOSSIL FUELS
FRACTURED RESERVOIRS
FRACTURES
FRACTURING
FUELS
GEOLOGIC AGES
GEOLOGIC FORMATIONS
HEIGHT
HYDRAULIC FRACTURES
HYDRAULIC FRACTURING
INFORMATION
LENGTH
MATERIALS
NORTH AMERICA
NUMERICAL DATA
OIL SHALES
PALEOZOIC ERA
STRESSES
TIME DEPENDENCE
USA