End-fire Vertical Marine Seismic Source Array

摘要

The paper is based upon an original idea that beaming the seismic source energy within the vertical angles of the explorationrninterest, source-generated interference can be reduced. The study emanates from previous on-shore work by Pan AmericanrnPetroleum (S. T. Martner, et. al.) and Atlantic Richfield (Elias Z. Ata, et.al.)rnThis new seismic source design significantly improves signal-to-noise ratio by enhancing signal in the presence of sourcegeneratedrninterference such as water-bottom reverberations, scatter, surface ghosting and the like, that are otherwise difficult,rnif not impossible to remove completely in data processing.rnThe current use of air-gun sub-arrays are mainly designed to attenuate bubble oscillation and are ineffective in reducingrnsource-generated interference resulting from geological complexities located above the exploration objectives. Although endfirernsource arrays have been used in land seismic surveys the same was never designed nor used in marine seismic surveysrndue to the popularity and predominance of air-gun sub-arrays. This current proposal involves the use of individual air-guns inrna near-vertical deployment whereby the topmost gun is fired first followed by guns located below with pertinent time delaysrnthat correspond to the sea-water velocity. Such end-fire source array will reinforce the downward propagating pressure wavernby constructive interference while attenuating all other wave propagation by destructive interference. Such destructiverninterference is physical, i.e., superimposing rarefaction upon pressure, thereby eliminating further propagation of suchrnpressure wave in water. Depending upon the exploration objectives a source array can be designed to beam source energyrntowards intended targets while avoiding beaming such energy in any other direction.rn(Copyright 2011, Offshore Technology Conference.)