Airgun Array Seismic Data Reconstruction via Multi-Frequency Approach
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Solution Overview
Problem
Seismic surveys using time-distributed airgun arrays introduce frequency notches in the source spectrum, leading to side-lobes and difficulties in data processing, especially when signal-to-noise levels are low or spatial reconstruction is challenging, limiting the effectiveness of deconvolution and spatial reconstruction methods.
Innovation Solution
A multi-frequency approach is employed to convert time-distributed seismic data into impulsive data by using multiple frequencies around notch frequencies, allowing for the elimination of notches and simultaneous source separation and reconstruction, without the need to vary the time-distribution sequence from shot to shot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If time-distributed airgun array firing is used, then peak energy is reduced and environmental impact is minimized, but frequency notches are introduced into the source spectrum causing side-lobes and processing difficulties
Solution Approach 1:
The patent applies parameter changes by modifying the time distribution sequence parameters (delays, intervals) of airgun firings to optimize the balance between peak energy reduction and spectral quality. By adjusting these temporal parameters, the method reduces notching effects while maintaining environmental benefits.
Solution Approach 2:
The patent implements dynamics by making the time distribution sequence variable rather than fixed. The sequence is adapted dynamically based on survey conditions, source configuration, and desired spectral characteristics, allowing optimization of both environmental impact and data quality.
2Loss of information
If deconvolution of distributed sequence is attempted, then signal in notches can be recovered, but noise is amplified and errors are introduced
Solution Approach 1:
The patent applies preliminary action by pre-planning and optimizing the time distribution sequence before data acquisition to minimize notching effects. This prevents the need for aggressive deconvolution operations that would amplify noise, thereby maintaining signal recovery capability without compromising reliability.
3Loss of information
If spatial reconstruction is attempted, then information from neighboring sources can be used to reconstruct missing frequencies, but the method is difficult where source sampling interval results in spatially aliased data
Solution Approach 1:
The patent applies parameter changes by optimizing the spatial arrangement and sampling interval parameters of airgun sources. By adjusting these parameters, the method ensures adequate spatial sampling that prevents aliasing while enabling effective spatial reconstruction of missing frequencies.
4Manufacturing precision
If airgun array is tuned to form impulsive source signature, then broadband spectral output is achieved, but peak energy is high and environmental damage occurs
Solution Approach 1:
The patent applies periodic action by using repeated, time-distributed firings of airguns in the array. Instead of single high-energy impulsive shots, the method uses multiple lower-energy firings distributed over time, maintaining spectral quality through cumulative effects while reducing peak energy and environmental impact.
Data Source
Figure 1
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Figure 4a~4b
AI summary
Acquiring seismic data using time-distributed sources and converting the acquired data into impulsive data using a multiple-frequency approach. The methods are performed in frequency-source location domain, frequency-wavenumber domain, or frequency-slowness domain. The methods are applicable to single source acquisition or simultaneous source acquisition.