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Seismic Interferometrypp, A Novel Exploration Tool

Stan Sansone

Zero phase seismic data has been, and is today, a goal geophysicists find an easy and adequate reference when interpreting seismic data. A patented and patent pending seismic exploration approach utilizing a technique described as Dual Frequency Seismic Interferometry© (1991-2004 U.S Patents 5,231,252, 5,335,208, 5,545,858 & Patents Pending) to collect and analyze exploration seismic data information is deployed and analyzed. Field experiments performed in 1991 and 1997 using receiver platforms and a two-transducer receiver to mimic a two-beam interferometer indicate that an analog earth propagating seismic information can be split using the two different transducers at some common point of observation. Seismic information recorded in such a way show remarkable sensitivities, as evidenced by the subtle trace and wavelet variations. Variations of 1 Hz, or a minuet fraction of the harmonic, are measurable. Variations between the two recorded wave fronts or beams are very subtle, and can lead to a diagnostic measure of phase information. Results indicate that principles of Interferometry, so valuable in material analysis, structural analysis, microscopy and surveying in the optical part of the wave spectrum may prove to be just as valuable in the acoustic and seismic portions of the wave spectrum. Interferometry is a tool whereby a wavefront is split using division of wavefront or division of amplitude. Interference was first observed by Robert Hooke (1635-1703) and studied by Newton (Newton’s rings). Interferometry and more specifically the Interferometer was discovered by Michelson in 1987 and as a result became America’s first Nobel laureate in physics. Interferometer is an instrument that utilizes interference phenomena for precise determinations of wavelength, frequency, spectral fine structure, indices of refraction and very small displacements. Interferometry also provides a measure of phase and is suggested to be a fundamental and arguably the most important parameter potentially containing more information than the parameters of amplitude and frequency. Amplitude is used as a direct detection tool (Chevron, Ostrander). Likewise, frequency is also used as a direct detection tool (BP, Partyka). It is suggested that phase may also be used as a direct detection tool, Phase Versus Offset-PVO©.