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Swept impact seismic technique (SIST)
Park, Choon Byong Miller, Richard D. Steeples, Don W. Black, Ross A.
Park, Choon Byong
Miller, Richard D.
Steeples, Don W.
Black, Ross A.
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Abstract
A coded seismic technique is developed that can result in a higher signal-to-noise ratio than a conventional single-pulse method does. The technique is cost-effective and time-efficient and therefore well suited for shallow-reflection surveys where high resolution and cost-effectiveness are critical A low-power impact source transmits a few to several hundred high frequency broad-band seismic pulses during several seconds of recording time according to a deterministic coding scheme. The coding scheme consists of a time encoded impact sequence in which the rate of impact (cycles/s) changes linearly with time providing a broad range of impact rates. Impact times used during the decoding process are recorded on one channel of the seismograph. The coding concept combines the vibroseis swept-frequency and the Mini-Sosie random impact concepts. The swept-frequency concept greatly improves the suppression of correlation noise with much fewer impacts than normally used in the Mini-Sosie technique. The impact concept makes the technique simple and efficient in generating high-resolution seismic data especially in the presence of noise. The transfer function of the impact sequence simulates a low-cut filter with the cutoff frequency the same as the lowest impact rate. This property can be used to attenuate low-frequency ground-roll noise without using an analog low-cut filter or a spatial source (or receiver) array as is necessary with a conventional single-pulse method. Because of the discontinuous coding scheme, the decoding process is accomplished by a "shift-and-stacking" method that is much simpler and quicker than cross-correlation. The simplicity of the coding allows the mechanical design of the source to remain simple. Several different types of mechanical systems could be adapted to generate a linear impact sweep. In addition, the simplicity of the coding also allows the technique to be used with conventional acquisition systems, with only minor modifications.
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This is the published version, also available here: http://dx.doi.org/10.1190/1.1444095.
Date
1996-11-01
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Society of Exploration Geophysicists
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Citation
Park, Choon Byong., Miller, Richard D., Steeples, Don W., Black, Ross A. "Swept impact seismic technique (SIST)" GEOPHYSICS(1996),61(6):1789. http://dx.doi.org/10.1190/1.1444095