Now showing items 1-20 of 456

    • Detection Of Subsurface Fractures And Permeable Zones By The Analysis Of Tube Waves 

      Beydoun, W. B.; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      In Vertical Seismic Profiling tube waves are generated by compressional waves impinging on subsurface fractures or permeable zones. The amplitude of tube waves is dependent upon the formation permeability, the length of ...
    • The Effects Of High Pressure-High Temperature On Some Physical Properties Of Ocean Sediments 

      Morin, Roger; Silva, Armand J. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      A series of laboratory experiments was conducted with four ocean sediments, two biogenic oozes and two clays. Permeability and thermal conductivity were directly measured as a function of porosity and the testing program ...
    • Acoustic Character Of Hydraulic Fractures In Granite 

      Paillet, Frederick I. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      Hydraulic fractures in homogeneous granitic rocks were logged with conventional acoustic-transit-time, acoustic-waveform, and acoustic-televiewer logging systems. Fractured intervals ranged in depth from 45 to 570m. and ...
    • Determination of Shear Wave Velocities in "Slow" Formations 

      Cheng, C. H.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      Direct determination of formation shear wave travel time is impossible in "slow" formations where the shear wave velocity is lower than the borehole fluid (mud) velocity. However, the Stoneley waves in these formations are ...
    • Effects of Casing on Full Waveform Acoustic Logs 

      Tubman, Kenneth M.; Cheng, C. H.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      A general expression is derived for the dispersion relations and the impulse response of a radially layered borehole. The. model geometry consists of a central fluid cylinder surrounded by an arbitrary number of solid ...
    • Seismic Waves in a Borehole - A Review 

      Toksoz, M. N.; Cheng, C. H.; Willis, M. E. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      The propagation of seismic waves in an open borehole is reviewed. The principal wave types are the refracted P and S waves and the two guided waves - pseudo-Rayleigh and Stoneley. The dispersion properties of the guided ...
    • Inversion Of Travel Time For Velocity 

      Willis, M.E. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      Common source velocities and borehole compensated (BC) estimates have been used to obtain formation velocity estimates from full waveform acoustic logs (Willis and Toksoz, 1982). With both of these methods the ...
    • Frequency and Scale Effects in the Optimization of Acoustic Waveform Logs 

      Paillet, Frederick L. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      Previously formulated scaling laws relating acoustic waveforms in boreholes to frequency, tool size and borehole diameter were investigated by repeated logging of the same test interval with different frequencies, and ...
    • Finite Difference Synthetic Acoustic Logs 

      Stephen, R. A.; Pardo-Casas, F.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      Synthetic seismograms of elastic wave propagation in a fluid-filled borehole were generated using both the finite difference technique and the discrete wavenumber summation technique. The latter is known to be accurate for ...
    • Approximate Effects of Off-Center Acoustic Sondes and Elliptic Boreholes Upon Full Waveform Logs 

      Willis, M. E.; Toksoz, M. N.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      Full waveform acoustic well logging has become instrumental to hydrocarbon exploration because of its ability to determine in situ velocity information for P and S waves as well as the attenuation (or absorption) of seismic ...
    • P And S Wave Velocity Determination 

      Willis, M. E.; Toksoz, M.N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)
      There are three general methods that can be used to determine formation velocities from full waveform logs. The first approach is to make use of the data from the entire waveform. This type of velocity analysis is performed ...
    • Dispersion Curves and Synthetic Microseismograms in Unbonded Cased Boreholes 

      Tubman, Kenneth M.; Cole, Stephen P.; Cheng, C. H.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      The dispersion relations and impulse response. are calculated for a geometry consisting of an arbitrary number of coaxial annuli surrounding a central cylinder. The annuli may be either solid or fluid. The formulation ...
    • Determination of Formation Properties in Cased Boreholes Using Full Waveform Acoustic Logs 

      Tubman, Kenneth M.; Cheng, C. H.; Toksoz, M. Nafi (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      Wave propagation in bonded and unbonded cased boreholes is examined through the calculation cif synthetic full waveform acoustic logs. The models consist of a central fluid borehole surrounded by a number of fluid and solid ...
    • The Study of Wave Propagation in a Borehole Using the Finite Difference Method 

      Pardo-Casas, Federico; Cheng, C. B.; Stephen, Ralph A. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      Synthetic microseismograms of elastic wave propagation in a fluid-filled borehole were generated using both the finite difference technique and the discrete wavenumber summation technique. For the finite difference ...
    • Full Waveform Acoustic Logging - Where We Are, Where We Are Going 

      Toksoz, M. Nafi; Cheng, C. H.; Garcia, Gilles (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      We have now completed the second year of the Full Waveform Acoustic Logging Consortium. During these two years, we have developed a good understanding of seismic wave propagation in a borehole through both theoretical ...
    • Applications of Finite Difference Synthetic Acoustic Logs 

      Stephen, R. A.; Pardo-Casas, F. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      Finite difference synthetic acoustic logs are suitable for studying wave propagation in vertically varying boreholes and in boreholes with continuously varying properties. Snapshots for the traditional smooth bore in a ...
    • Application of Full Waveform Acoustic Logging Data to the Estimation of Reservoir Permeability 

      Mathieu, F.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      Development of borehole geophysics has recently focused on reservoir characterization. Within this effort, extensive full waveform acoustic surveys have demonstrated a correlation between the occurance of open fractures ...
    • Nullerical Studies of Body Wave Amplitudes in Full Waveform Acoustic Logs 

      Zhang, Jinzhong; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      The amplitudes of P and S head waves in a full waveform acoustic log microseismogram are studied numerically as a function of borehole and formation parameters. The technique used is contour integration around the respective ...
    • Analysis of Full Waveform Acoustic Logging Data in "Soft" Formations 

      Barton, C.; Cheng, C. R.; Toksoz, M. N. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      Direct recording of formation shear wave travel time is not possible in "soft" formations where the shear velocity is lower than the borehole fluid velocity. The borehole Stoneley wave is quite sensitive to changes in ...
    • Determination of Shear Wave Velocity and Attenuation From Waveforms in Low Velocity Formations 

      Toksoz, M. Nafi; Wilkens, R. H.; Cheng, C. H. (Massachusetts Institute of Technology. Earth Resources Laboratory, 1984)
      In boreholes where formation shear velocity is lower than borehole fluid velocity neither refracted shear waves nor pseudo-Rayleigh waves can propagate. When frequency response of the sonde does not extend to low frequencies ...