Airgun Source Array Low Frequency Output Optimization
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Solution Overview
Problem
The low frequency output of marine airgun seismic source arrays is limited by the resonance frequency of the largest airgun bubble volume, which is inversely proportional to the cube-root of the airgun chamber volume, making it challenging to achieve significant low frequency source output without increasing the total gas volume.
Innovation Solution
The solution involves designing a source array where all or some airguns are activated to generate an effective bubble energy by fully frequency locking airgun bubbles, releasing the largest quantity of high pressure gas into one location, and optimizing the arrangement of airguns to maximize low frequency output, such as by increasing the firing pressure and rearranging the airguns to achieve a larger effective bubble volume relative to the total source volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the largest airgun bubble volume is increased to decrease bubble frequency and increase low frequency output, then the low frequency source output is improved, but the total gas volume required increases substantially
Solution Approach 1:
Multiple airguns are clustered together in close proximity (separated by less than one metre) so their bubbles coalesce into one non-spherical bubble, creating a combined bubble volume effect without requiring proportionally more total gas. The clustered airguns act as a single integrated source with enhanced low frequency output.
Solution Approach 2:
The source array is divided into a cluster of smaller airguns that collectively produce the low frequency output, rather than using a single large airgun. This segmentation allows achieving the same low frequency effect with distributed, manageable components.
2Power
If airguns are clustered closely together to create a combined bubble, then the low frequency output is enhanced, but the complexity of arranging and positioning the airguns increases
Solution Approach 1:
Multiple airguns are merged into a single functional cluster unit with standardized spacing (less than one metre), simplifying the overall system design while achieving enhanced low frequency output through the combined bubble effect.
3Manufacturing precision
If the airgun chamber volume is increased to achieve maximum destructive interference of bubble amplitude, then the spectral flatness is improved, but the low frequency output remains limited by the resonance frequency
Solution Approach 1:
The invention prioritizes merging multiple airguns into a clustered configuration that coalesces bubbles, thereby enhancing low frequency output. This approach accepts some trade-off in spectral flatness optimization while achieving the primary goal of improved low frequency source output.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly increases the low frequency output of the source array, allowing for a larger effective bubble volume, which enhances the seismic data acquisition capabilities by improving the detection of subsurface formations and hydrocarbon deposits without increasing the total gas volume.
Implementation Method 1
The low frequency output of marine airgun seismic sources is limited by the resonance frequency of the largest airgun bubble volume in the source array. This oscillation frequency, also referred to as the fundamental bubble frequency, is given by the well-known Rayleigh-Willis formula
Implementation Method 2
the clustered airguns are typically separated by less than one metre, and where the airgun bubbles coalesce into one non-spherical bubble
Data Source
AI summary
A technique provides a source design and method for increasing low frequency output of a marine source array. The approach comprises providing a plurality of airguns. At least some of the airguns are activated to generate an effective bubble energy. The effective bubble energy may be optimized through use, preparation and/or arrangement of the airguns.