Elastic waves through a simulated fractured medium
- Schlumberger-Dol Research, Ridgefield, CT (United States)
- Schlumberger Cambridge Research, Cambridge (United Kingdom)
Ultrasonic velocities were measured on a block composed of lucite plates with roughened surfaces pressed together with a static normal stress to simulate a fractured medium. The measurements, normal, parallel, and oblique to the fractures, show that for wavelength much larger than the thickness of an individual plate, the block can be modeled as a particular type of transversely isotropic (TI) medium that depends on four parameters. This TI medium behavior is the same as that of an isotropic solid in which are embedded a set of parallel linear slip interfaces, specified by (1) the excess compliance tangential to the interfaces and (2) the excess compliance normal to the interfaces. At all static stress levels, the authors inverted the data for the background isotropic medium parameters and the excess compliances. The background parameters obtained were basically independent of stress level and agreed well with the bulk properties of the lucite. The excess compliances decreased with increasing static closing stress, implying that increasing static stress forces asperities on either side of a fracture into greater contact, gradually eliminating the excess compliance that gives rise to the anisotropy. A medium with such planes of excess compliance has been shown, theoretically, to describe the behavior of a medium with long parallel joints, as well as a medium with embedded parallel microcracks.
- OSTI ID:
- 5931063
- Journal Information:
- Geophysics; (United States), Journal Name: Geophysics; (United States) Vol. 58:7; ISSN GPYSA7; ISSN 0016-8033
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
ACOUSTIC DETECTION
ACOUSTIC MEASUREMENTS
ATTENUATION
CHARGED PARTICLE DETECTION
DATA ANALYSIS
DETECTION
FUNCTIONS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
RADIATION DETECTION
RESPONSE FUNCTIONS
SEISMIC SURVEYS
SEISMIC WAVES
SONIC LOGGING
SOUND WAVES
SURVEYS
ULTRASONIC WAVES
WAVE PROPAGATION
WELL LOGGING