Air-gun Array Spatial Distribution Optimization for Directivity Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern marine seismic exploration using tuned air-gun arrays faces challenges with strong directivity in source signatures, which degrades imaging quality and is exacerbated by low signal-to-noise ratios, particularly in the vicinity of ghost and interference notches, limiting the effective frequency bandwidth and take-off angle width.
Innovation Solution
A method to reduce air-gun source directivity by optimizing the spatial distribution of air-guns, involving adjusting the spacing and depth locations of air-guns within specific ranges to maximize an objective function that correlates with effective take-off angle width, and synchronizing firing times across different depths to align downgoing primaries, thereby reducing inline directivity and compensating for ghost and interference notches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a tuned air-gun array is used to achieve higher peak-to-bubble ratio and better absolute energy, then the source signature has strong directivity which degrades imaging quality
Solution Approach 1:
The patent applies local quality by optimizing the spatial distribution of individual air-guns within the array. Each air-gun's position (inline location and depth) is specifically adjusted to control the spatial distribution of acoustic energy, thereby reducing directivity while maintaining the overall power of the array. The objective function evaluates the spatial distribution effects on ghost and interference notches at different locations.
Solution Approach 2:
The patent changes physical parameters of the air-gun array by adjusting spacing between adjacent air-guns (3-5m) and horizontal spacing (1-3m). These parameter changes optimize the spatial distribution to reduce directivity effects. The optimization process adjusts inline locations and depth locations to maximize the objective function while maintaining constraints on spacing parameters.
2Object-generated harmful factors
If directivity-targeted source signature deconvolution is used to attenuate directivity effect, then processing complexity increases and performance depends on signal to noise ratio
Solution Approach 1:
The patent applies preliminary action by reducing directivity at the source through optimized spatial distribution before the seismic data is acquired. By pre-optimizing the air-gun array configuration to minimize directivity effects, the need for complex post-acquisition deconvolution processing is reduced. This prevents directivity problems rather than correcting them later, simplifying the overall processing workflow.
3Object-generated harmful factors
If air-gun spacing is reduced to improve spatial distribution, then interference between air-gun wave fields increases and collision risk increases
Solution Approach 1:
The patent optimizes spacing parameters within specific ranges: spacing between adjacent air-guns is controlled at 3-5m and horizontal spacing at 1-3m. These parameter values are determined through optimization to achieve uniform spatial distribution while avoiding strong interference between wave fields and reducing collision risk. The objective function evaluation guides the selection of optimal spacing parameters that balance distribution uniformity with interference avoidance.
Data Source
AI summary
A method for reducing inline directivity of an air-gun source signature by optimizing spatial distribution of air-guns is provided according to the present application, which relates to a field of design and optimization of an air-gun source. An evaluation standard in the air-gun distribution in an air-gun array direction is proposed. By a combination optimization along both the inline and depth directions, a design scheme having evidently broader effective bandwidth and effective take-off angle width than a design scheme of a conventional source is obtained, with which the directivity of the air-gun source signature can be reduced.