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Title: Seismic wave propagation in anisotropic waveguides
Author: Lou, Min
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1992
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The thesis studies the propagation of guided-waves in crack-induced anisotropic media, and exploits the potential applications of guided-waves in production seismology by crosshole seismic surveys. Firstly, by extending Crampin's technique for calculating surface-waves dispersion, we present a procedure for determining the dispersion and amplitude/depth distribution of guided-waves in multilayered anisotropic media. By using the developed techniques, we study the propagation behaviour of guided-waves in crack-induced anisotropic waveguides. Our studies have shown that: (a) almost any interface, or combination of interfaces, will support the propagation of guided-waves in crosshole seismic surveys, if signals at appropriate frequencies, amplitudes, and polarizations can be generated in one well and recorded at appropriate levels in neighbouring wells; (b) in crack-induced anisotropic waveguides, the distinct families of Rayleigh and Love modes of guided-waves in isotropic waveguides combine into a single family of Generalized modes with 3-D elliptical particle motions; (c) guided-waves are very sensitive to the internal properties and geometry of waveguide, and such guided-wave characteristics vary substantially for different crack orientations, crack densities, crack saturations, and crack aspect ratios. Guided-waves have been clearly identified from a shallow crosshole survey at the Conoco Borehole Test Facility (CBTF) and, in many circumstances, have dominant energy in the seismograms. We have demonstrated that guided-waves in crosshole surveys have two potential applications: continuity tests of plane-layered reservoirs; and monitoring Enhanced Oil Recovery (EOR) operations for thin-layered sedimentary reservoirs. Finally, we have modelled the propagation of guided-waves in two particular waveguides: a crack-controlled channel which may be formed in hydraulic fracturing in geothermal reservoirs; and an active fault zone. The study of such guided-waves is useful in understanding the fracture structure and distribution in geothermal reservoirs, and in delimiting a fault zone or monitoring the stress and fracture development inside an active fault zone.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available