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• E-ISSN: 1365-2478

## DEVELOPMENT OF MORE EFFICIENT AIRGUN ARRAYS: THEORY AND EXPERIMENT*

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• Source: Geophysical Prospecting, Volume 30, Issue 6, Nov 1982, p. 752 - 773
• DOI:
• Published online: 27 Apr 2006

### Abstract

A

Source strength of an airgun array may be increased by:

• —  utilizing higher pressure,
• —  increasing total array volume,
• —  employing more guns,
• —  improving gun efficiency.

One measure of gun efficiency is “specific source strength”, *, defined as source strength per unit quantity of air used. Typical units are MPa m/l. Most developments are directed toward increasing gun pressure and/or gun volume to increase source strength of the array. These efforts require that more air compressors be installed onboard the ship. Consequently, a larger ship may be needed for the additional compressors, guns, and auxiliary equipment.

A development program was initiated in 1976 to increase source strength of the array without using a larger ship. New guns were designed and built—one for 41.4 MPa and 7.37 liter (6000 p.s.i./450 in3) operation and another with 13.8 MPa and 4.92 liter (2000 p.s.i./300 in3) capability. Experiments were conducted with these new guns (and existing guns) over a range of pressures from 13.8 to 41.4 MPa (2000 to 6000 p.s.i.).

Design of the new guns was aided by a mathematical model. The model relates physical dimensions of the airgun to acoustic pressure in the water. It consists of four nonlinear differential equations relating

• —  shuttle motion,
• —  bubble pressure,
• —  chamber pressure,

The last equation is the “free‐bubble‐oscillation equation” and represents the ideal case of a pressurized bubble released instantaneously in water. The three other equations modify this ideal case; the four equations together model an airgun of the type manufactured by Bolt Associates, Inc.

/content/journals/10.1111/j.1365-2478.1982.tb01337.x
2006-04-27
2020-03-31

References

1. Giles, B. F. and Johnston, R. C.1973, System approach to airgun array design, Geophysical Prospecting21, 77–101.
2. Johnston, R. C.1980, Comparison of 2000 and 6000 p.s.i. airguns: Theory and experiment, Geophysical Prospecting28, 700–715.
3. Keller, J. B. and Kolodner, I. I.1956, Damping of underwater bubble oscillations, Journal of Applied Physics27, 1152–1161.
4. Safar, M. H.1976, The radiation of acoustic waves from an airgun, Geophysical Prospecting24, 756–772.