Numerical-model developments for stimulation technologies in the Eastern Gas Shales Project

Technical Report · Tue Jan 01 00:00:00 EST 1980

OSTI ID:6353031

Barbour, T G; Maxwell, D E; Young, C

These efforts were directed towards the development of a numerical tensile failure model that could be used to make a parameter sensitivity study of the EGSP wellbore stimulation methods for gas recovery in Devonain shales, calculations were performed using the NTS Multi-Frac Mineback Experiments as the geometry, boundary conditions and material properties of the models. Several major accomplishments were achieved during this task. These include: development of a Crack and Void Strain (CAVS) tensile failure model for one-dimensional fracture analysis using the one-dimensional geometries available in SAI's STEALTH 1-D finite-difference code; modification of the original CAVS tensile failure criteria to improve its representation of multiple fracture development by introducing a logic that adjusts the material's tensile strength (both for crack initiation and crack propagation) according to the degree of cracking that has occurred; adding a submodel to CAVS to allow for cracking propping when a crack is reclosed and to require energy to be expanded during this process; adding a submodel to CAVS to allow for crack pressurization when a crack void strain is in communication with the fluid pressure of the borehole; and performing a parameter sensitivity analysis to determine the effect that the material properties of the rock has on crack development, to include the effects of yielding and compaction. Using the CAVS model and its submodels, a series of STEALTH calculations were then performed to estimate the response of the NTS unaugmented Dynafrac experiment. Pressure, acceleration and stress time histories and snapshot data were obtained and should aid in the evaluation of these experiments. Crack patterns around the borehole were also calculated and should be valuable in a comparison with the fracture patterns observed during mineback.

• Research Organization: Science Applications, Inc., Fort Collins, CO (USA)
• DOE Contract Number: AM21-78MC08216
• OSTI ID: 6353031
• Report Number(s): DOE/MC/08216-1378; ON: DE83008489
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
58 GEOSCIENCES
BLACK SHALES
CRACK PROPAGATION
FRACTURE PROPERTIES
PARAMETRIC ANALYSIS
EXPLOSIVE FRACTURING
MATHEMATICAL MODELS
NATURAL GAS WELLS
C CODES
COMPUTER CODES
DEVONIAN PERIOD
S CODES
WELL STIMULATION
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHATTANOOGA FORMATION
COMMINUTION
ENERGY SOURCES
FOSSIL FUELS
FRACTURING
FUELS
GEOLOGIC AGES
GEOLOGIC FORMATIONS
MATERIALS
MECHANICAL PROPERTIES
OIL SHALES
PALEOZOIC ERA
STIMULATION
WELLS
030900* - Natural Gas- Artificial Stimulation
Plowshare- (-1989)
580300 - Mineralogy
Petrology
& Rock Mechanics- (-1989)