Systems and Methods for Optimizing Low Frequency Output from Airgun Source Arrays

Abstract

Systems and methods for optimizing low frequency output of marine sources are described. The marine source arrangements and associated methods disclosed herein seek to fully frequency lock bubbles emitted by airguns in close proximity to one another. In this manner, larger effective bubble volumes can be achieved, thus increasing low frequency output.

What is claimed is: 
     
         1 . A method for increasing low frequency output of a marine source array, comprising:
 providing a plurality of airguns;   identifying a largest effective bubble volume for the marine source array;   arranging at least some of the airguns in such a way to achieve the largest effective bubble volume upon activation of the airguns; and   activating the airguns.   
     
     
         2 . A method according to  claim 1 , further comprising identifying a desired ratio between the largest effective bubble volume and the total source volume. 
     
     
         3 . A method according to  claim 1 , wherein identifying the largest effective bubble volume comprises assessing factors that limit usage of the total source volume of the marine source array. 
     
     
         4 . A method according to  claim 1 , further comprising arranging at least some of the airguns to achieve higher frequencies relative to the frequency output of the largest effective bubble volume. 
     
     
         5 . A method according to  claim 4 , wherein the higher frequency output is used to flatten the spectrum of the source array. 
     
     
         6 . A method according to  claim 1 , the method being carried out during one of a towed marine seismic survey, a vertical seismic profiling survey, a seabed seismic survey and a borehole seismic survey. 
     
     
         7 . A method for increasing low frequency output of a marine source array, comprising:
 providing a plurality of airguns;   arranging the airguns in close proximity to one another; and   activating the airguns to fully frequency lock the bubbles emitted by the airguns.   
     
     
         8 . A method according to  claim 7 , wherein the marine source array has a total source volume, and wherein activating the airguns achieves an effective bubble volume of at least 50% of the total source volume. 
     
     
         9 . A method according to  claim 7 , wherein the marine source array has a total source volume, and wherein activating the airguns achieves an effective bubble volume of 100% of the total source volume. 
     
     
         10 . A method according to  claim 7 , wherein arranging the airguns comprises arranging the airguns in a hexagonal manner. 
     
     
         11 . A method according to  claim 7 , the method being carried out during one of a towed marine seismic survey, a vertical seismic profiling survey, a seabed seismic survey and a borehole seismic survey.