SYSTEM APPROACH TO AIR‐GUN ARRAY DESIGN *

To specify intelligently a nondynamite source in a marine seismic data‐collection system, it is important to use all known parameters of the system—source, receiver, and recording‐system characteristics. A technique has been developed to design the far‐field pressure pulse of an air‐gun array by taking these parameters into account.

Important source variables to consider are interaction among guns in the array and the depth of the array. Near‐field pressure signatures of individual guns, which are relatively unaffected by boundaries, have been used to‘construct’the far‐field pressure pulse of the array by considering these variables. Comparison between constructed pulses and measured far‐field pulses shows substantial agreement.

Streamer depth and recording‐system bandpass should also be considered when designing an air‐gun array. Comparison of far‐field pressure pulses for several bandpasses clearly shows the importance of considering this variable; e.g., the initial pulse is severely attenuated when a high‐cut filter is used. Likewise, an additional filtering effect due to the streamer's proximity to the surface should be taken into account.

Design of an air‐gun array using the principles just outlined are illustrated by an example.