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Seismic methods applied to rock mechanics
27A attempt to locate the flood zone. Traveltime tomography located the flood zone more precisely than amplitude tomography, but both have a role to play in real,heterogeneous reservoir rocks.
941208 High-frequency sparker source for the borehole environment Rechtien, R D; Hambacker, K L; Ballard, R F Geophysics V58, N5, May 1993, P660-669 A simple arc discharge seismic source has been constructed using off-the-shelf components to satisfy the need for a low cost source for shallow subsurface tomography. It produces a seismic pulse with dominant frequency about 1.5kHz and halfpower bandwidth in excess of lkHz. Field evaluation shows it provides a repeatable seismic signature and signal-to-noise ratio of at least 35dB at borehole spacing 33.2m.
941209 High resolution seismic reflections in a potash mine Gendzwill, D J; Brehm, R Geophysics 1/58, N5, May 1993, P741-748 Geophysical methods are preferred to drilling in reconnaissance of salt mines as there is no chance of damaging aquifer contacts. Vertical seismic reflection techniques will resolve more detail than refraction or electromagnetic methods and at much greater penetration than radar. A hammer source can be used but the geophones must be firmly anchored to the rock to record high frequency signals. The method has been applied to a Saskatchewan potash mine. The method, source and receiver arrays, and roof and floor profiles obtained are described.
941210 Vertical open fractures and shear-wave velocities derived from VSPs, full waveform acoustic logs, and televiewer data Lefeuvre, F; Turpening, R; Caravana, C; Born, A; Nicoletis, L Geophysics V58, N6, June 1993, P818-834 Fast and slow shear wave velocities have been derived from a 9-component zero offset VSP in limestone, dolomite, and anhydrite. Data are compared to shear wave velocities from two full waveform acoustic logs. The propagator matrix technique was used to detect and measure azimuthal anisotropy. General fit between the 3 data sets is good. It was suspected that the formations showing birefringence are vertically fractured. The behaviour of the Stoneley waves on the full waveform logs was examined to confirm this. Borehole televiewer data from a nearby well fit fractures indicated by the VSP.
941211 Geological and geophysical investigations at the dam site of Kalamoti (Chios, Greece) (In French) Stournaras, G; Papadopoulos, T; Panagopoulos, A Int Assoc Engng Geol Bull N47, April 1993, P151-158 The construction of the Kalamoti dam on the island of Chios provided an opportunity to evaluate geoelectric and electromagnetic methods for mapping lithological and tectonic boundaries in Neogene formations of the foundations. The marls, marly sandstones, conglomerate, and tuffaceous rocks of the formation and the major discontinuities are illustrated. Fractures indicated by the geophysical tests have been entirely or partially verified during subsequent construction work.
941212 Seismic methods applied to rook mechanics Young, R P ISRM News J V1, N3, June 1993, P4-18 Seismic methods have been widely used in the field in exploration and monitoring and have recently been adopted in the laboratory, with CAT methods used to visualise processes inside test specimens. Concurrent application of these techniques is suggested. Ultrasonic imaging and acoustic emission studies in the laboratory and seismic imaging and induced seismicity studies in the field are described. Thermally induced fracturing, damage evolution, and hydrofracturing of granite samples has been followed. Failure initiation, fracturing, rockbursts, and seismicity have been monitored in underground structures.
941213 Digital filtering techniques for interpreting seismic cone data Baziw, E J J Geotech Engng Div ASCE Vl19, N6, June 1993, P998-1018 In the seismic cone penetration test, seismic waves generated at the surface are recorded using transducers in an electric piezocone. Sensitive, fast-response transducers are required, which show correspondingly noisy time-domain characteristics. A digital filter based on frequency domain filtering using a cross-correlation algorithm is presented to assist in SCPT data interpretation. The method proposed makes use of the computer code PSCrossCor in synthesising cross-correlation filter concepts. Data from three sites are used to compare the effectiveness of this approach and that based on established crossover methods in determining seismic velocities.
941214 Automated surface wave method: field testing Nazarian, S; Desai, M R J Geotech Engng Div ASCE Vl19, N7, July 1993, P10941111 The spectral analysis of surface waves (SASW) technique for determining the shear wave velocity profile and stiffness profile of soil sites and pavements is described. An automated method for the construction of the dispersion curve used in determining the stiffness profile from the field data is presented.
941215 Automated surface wave method: inversion technique Yuan, D; Nazarian, S J Geoteeh gngng Div ASCE V119, N7, July 1993, P11121126 An automated algorithm for determination of the representative dispersion curve from field data in the spectral analysis of surface waves (SASW) method was described in a companion paper. A method is here illustrated for simultaneous determination of shear wave velocity and stiffness profiles from the dispersion curve, using a technique based on the general inverse procedure. This reduces the time and reliance on engineering judgment required if the normal trial and error (forward modelling) approach is used.
941216 Method to derive dips from bedding boundaries in borehole images Antoine, J N; Delhomme, J P SPE Form Eval I,'8, N2, June 1993, P96-102 Electrical imaging tools with dense arrays of electrodes and high vertical sampling rates can provide detailed images of borehole walls. Using a pattern recognition algorithm which extracts the bedding boundary traces on each image and a
941208 High-frequency sparker source for the borehole environment Rechtien, R D; Hambacker, K L; Ballard, R F Geophysics V58, N5, May 1993, P660-669 A simple arc discharge seismic source has been constructed using off-the-shelf components to satisfy the need for a low cost source for shallow subsurface tomography. It produces a seismic pulse with dominant frequency about 1.5kHz and halfpower bandwidth in excess of lkHz. Field evaluation shows it provides a repeatable seismic signature and signal-to-noise ratio of at least 35dB at borehole spacing 33.2m.
941209 High resolution seismic reflections in a potash mine Gendzwill, D J; Brehm, R Geophysics 1/58, N5, May 1993, P741-748 Geophysical methods are preferred to drilling in reconnaissance of salt mines as there is no chance of damaging aquifer contacts. Vertical seismic reflection techniques will resolve more detail than refraction or electromagnetic methods and at much greater penetration than radar. A hammer source can be used but the geophones must be firmly anchored to the rock to record high frequency signals. The method has been applied to a Saskatchewan potash mine. The method, source and receiver arrays, and roof and floor profiles obtained are described.
941210 Vertical open fractures and shear-wave velocities derived from VSPs, full waveform acoustic logs, and televiewer data Lefeuvre, F; Turpening, R; Caravana, C; Born, A; Nicoletis, L Geophysics V58, N6, June 1993, P818-834 Fast and slow shear wave velocities have been derived from a 9-component zero offset VSP in limestone, dolomite, and anhydrite. Data are compared to shear wave velocities from two full waveform acoustic logs. The propagator matrix technique was used to detect and measure azimuthal anisotropy. General fit between the 3 data sets is good. It was suspected that the formations showing birefringence are vertically fractured. The behaviour of the Stoneley waves on the full waveform logs was examined to confirm this. Borehole televiewer data from a nearby well fit fractures indicated by the VSP.
941211 Geological and geophysical investigations at the dam site of Kalamoti (Chios, Greece) (In French) Stournaras, G; Papadopoulos, T; Panagopoulos, A Int Assoc Engng Geol Bull N47, April 1993, P151-158 The construction of the Kalamoti dam on the island of Chios provided an opportunity to evaluate geoelectric and electromagnetic methods for mapping lithological and tectonic boundaries in Neogene formations of the foundations. The marls, marly sandstones, conglomerate, and tuffaceous rocks of the formation and the major discontinuities are illustrated. Fractures indicated by the geophysical tests have been entirely or partially verified during subsequent construction work.
941212 Seismic methods applied to rook mechanics Young, R P ISRM News J V1, N3, June 1993, P4-18 Seismic methods have been widely used in the field in exploration and monitoring and have recently been adopted in the laboratory, with CAT methods used to visualise processes inside test specimens. Concurrent application of these techniques is suggested. Ultrasonic imaging and acoustic emission studies in the laboratory and seismic imaging and induced seismicity studies in the field are described. Thermally induced fracturing, damage evolution, and hydrofracturing of granite samples has been followed. Failure initiation, fracturing, rockbursts, and seismicity have been monitored in underground structures.
941213 Digital filtering techniques for interpreting seismic cone data Baziw, E J J Geotech Engng Div ASCE Vl19, N6, June 1993, P998-1018 In the seismic cone penetration test, seismic waves generated at the surface are recorded using transducers in an electric piezocone. Sensitive, fast-response transducers are required, which show correspondingly noisy time-domain characteristics. A digital filter based on frequency domain filtering using a cross-correlation algorithm is presented to assist in SCPT data interpretation. The method proposed makes use of the computer code PSCrossCor in synthesising cross-correlation filter concepts. Data from three sites are used to compare the effectiveness of this approach and that based on established crossover methods in determining seismic velocities.
941214 Automated surface wave method: field testing Nazarian, S; Desai, M R J Geotech Engng Div ASCE Vl19, N7, July 1993, P10941111 The spectral analysis of surface waves (SASW) technique for determining the shear wave velocity profile and stiffness profile of soil sites and pavements is described. An automated method for the construction of the dispersion curve used in determining the stiffness profile from the field data is presented.
941215 Automated surface wave method: inversion technique Yuan, D; Nazarian, S J Geoteeh gngng Div ASCE V119, N7, July 1993, P11121126 An automated algorithm for determination of the representative dispersion curve from field data in the spectral analysis of surface waves (SASW) method was described in a companion paper. A method is here illustrated for simultaneous determination of shear wave velocity and stiffness profiles from the dispersion curve, using a technique based on the general inverse procedure. This reduces the time and reliance on engineering judgment required if the normal trial and error (forward modelling) approach is used.
941216 Method to derive dips from bedding boundaries in borehole images Antoine, J N; Delhomme, J P SPE Form Eval I,'8, N2, June 1993, P96-102 Electrical imaging tools with dense arrays of electrodes and high vertical sampling rates can provide detailed images of borehole walls. Using a pattern recognition algorithm which extracts the bedding boundary traces on each image and a