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A field test of an electrodeless arc discharge, borehole seismic source

Journal Article · · Geophysics; (United States)
DOI:https://doi.org/10.1190/1.1443371· OSTI ID:5453003
;  [1]
  1. Southwest Research Inst., San Antonio, TX (United States)

Waveforms generated by an impulsive, 1.2 kJ, seven-conductor wireline electrodeless arc discharge borehole seismic source or sparker at Texaco's Humble, TX field test site were recorded by three borehole senor arrays: two free-hanging hydrophone streamers in in-line boreholes at 82 m and 170 m from the source well and a grouted, three-component geophone string in a borehole 110 m from the source well. A repeatability test of the source, consisting of single firings of the source at a rate of 1 firing per 5 s, showed very clean, very strong, Ricker-like wavelets. Despite a high-degree of attenuation (exact value of Q is not known), the useful frequency passband of the wavelets was from 200 Hz to 1,200 Hz for the data recorded by the 82-m offset hydrophones and 200 Hz to 500 Hz for the 170-m hydrophones. Using 62 single-firing wavelets recorded in the 82-m offset well gave mean and median cross correlations greater than 0.96 with standard deviations less than 0.02. A stack test, consisting of 1,2,4,8,16, and 32-stacked waveforms, confirmed the shape, strong S/N ratio, and high correlations of the sparker output. The 32-stack, which took less than 3 minutes to generate, was recorded by the noisy, near-surface geophones at a raypath distance of nearly 300 m.

OSTI ID:
5453003
Journal Information:
Geophysics; (United States), Journal Name: Geophysics; (United States) Vol. 58:11; ISSN GPYSA7; ISSN 0016-8033
Country of Publication:
United States
Language:
English