P And S Wave Velocity Determination

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 either in the frequency domain (i.e. f-k analysis or the two station method) or in the time domain (I.e. velocity spectral analysis). The second approach is to identify the P wave pulses on individual traces and to determine delay times between traces. In conventional acoustic logging this technique has been used successfully to determine the compressional wave velocities. The third approach' is to use the phase velocity of the gUided waves (Pseudo-Rayleigh) to determine the shear velocity. Each of these approaches have certain advantages and limitations depending on the tool characteristics (number of records, frequency response), formation properties (high or low shear velocity), and computation times required. The effect of these parameters upon each method of velocity determination is presented

Elastic wave propagation in a highly scattering medium - a diffusion approach

The principle of conservation of energy, in the form of the equation of radiative transfer, is used to treat the case of strong scattering of elastic waves. If the medium is isotropic, if all the energy present has been scattered many times, and if the time and distance scales of the problem are long compared to the time and distance scales of the scattering process, then the average flow of energy is described by the diffusion equation with an additional term representing linear dissipation to heat. Model seismic experiments using holes drilled in aluminum plates as scatterers confirm the applicability of the formalism. The diffusion formalism qas been successfully applied to lunar seismograms and to some Earth data. The results of studies of lunar seismograms show that the zone of strong scattering on the Moon is confined to a near surface zone.           ARK: https://n2t.net/ark:/88439/y064280 Permalink: https://geophysicsjournal.com/article/102 &nbsp