Investigation of equivalent porous medium permeability in networks of discontinuous fractures

Technical Report · Fri Apr 01 04:00:00 EST 1983

OSTI ID:5472384

Long, J C.S.

The purpose was to determine when a fracture system behaves as a porous medium and when it does, what is the appropriate permeability tensor for the medium. A volume of fractured rock can be said to behave like a representative volume of an equivalent porous medium when (1) there is an insignificant change in the value of the equivalent permeability with a small addition or subtraction to the test volume and (2) an equivalent permeability tensor exists which predicts the correct flux when the direction of a constant gradient is changed. A two-dimensional fracture system model was developed. The density, size, orientation, and location of fractures in an impermeable matrix are random variables in the model. Simulated flow tests through the models measure directional permeability, k/sub g/. The modeling techniques were applied to data from the Atomic Energy of Canada Ltd.'s Underground Research Laboratory facility in Manitoba, Canada. The permeabilities of models with uncorrelated length and aperture were smaller than for correlated models. A Monte Carlo type study showed that analysis of steady state packer tests would consistently underestimate the mean aperture. Finally, extension of the model to three dimensions is discussed where fractures are discs randomly located in space. 90 references, 90 figures, 22 tables.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5472384
• Report Number(s): LBL-16259; ON: DE84003040
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
DATA
DENSITY
FAILURES
FINITE ELEMENT METHOD
FLUID FLOW
FRACTURES
INFORMATION
MATERIALS
MATHEMATICAL MODELS
MATHEMATICS
NUMERICAL DATA
NUMERICAL SOLUTION
PERMEABILITY
PHYSICAL PROPERTIES
POROUS MATERIALS
REGRESSION ANALYSIS
ROCKS
STATISTICS
TENSORS
THEORETICAL DATA