Wavefield Separation in 3D Dual Sensor Towed Streamer Data
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Solution Overview
Problem
Current methods for separating upgoing and downgoing wavefield components in 3D dual sensor towed streamer seismic data fail to properly handle aliased energy in the cross-streamer direction, leading to incorrect scaling and separation of wavefield components.
Innovation Solution
The method involves transforming pressure records and vertical particle velocity records into the inline wavenumber domain and applying series of scaling filters calculated for different cross-streamer wavenumber ranges, allowing for accurate separation of upgoing and downgoing wavefield components without explicit trace interpolation, utilizing the cyclic properties of the FFT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wavefield separation methods are used in 3D dual sensor towed streamer data, then processing is simplified, but aliased energy in the cross-streamer direction causes incorrect scaling and separation of wavefield components
Solution Approach 1:
The patent divides the cross-streamer wavenumber range into multiple segments (positive and negative wavenumber ranges) and applies different scaling filters to each segment. This segmentation allows proper handling of aliased energy by treating different wavenumber regions separately, resolving the contradiction between maintaining simple processing and achieving accurate wavefield separation.
Solution Approach 2:
The patent changes the scaling filter parameters based on the cross-streamer wavenumber range. Different scaling filters are applied for positive and negative wavenumber ranges, with the filters being calculated using specific wavenumber ranges as parameters. This parameter change enables accurate scaling of wavefield components while managing the complexity through systematic parameter variation.
2Reliability
If trace interpolation is used to handle aliased energy, then spatial aliasing is reduced, but computational complexity and processing time increase
Solution Approach 1:
The patent extracts and handles aliased energy separately by applying different scaling filters to different wavenumber ranges. Instead of using computationally intensive trace interpolation, the method extracts the aliased component through the scaling filter operation and processes it independently, reducing processing time while maintaining reliability in handling aliased energy.
3Ease of operation
If a single scaling filter is applied to all wavenumbers, then processing is simple, but wavefield components cannot be correctly separated when aliased energy is present
Solution Approach 1:
The patent applies different scaling filters to different local regions of the wavenumber spectrum (positive and negative cross-streamer wavenumber ranges). Each local region receives a scaling filter tailored to its specific wavenumber characteristics, enabling accurate wavefield component separation while maintaining ease of operation through localized processing rather than global complexity.
Data Source
AI summary
Pressure records and vertical particle velocity records from dual sensor towed streamer data are transformed to the inline wavenumber domain. A series of scaling filters are applied to the transformed vertical particle velocity records at each inline wavenumber, wherein each of the series of scaling filters is calculated for a different cross-streamer wavenumber range and in blocks of inline traces in which all seismic events are approximately linear. The pressure spectrum and the scaled vertical particle velocity spectrum are combined to separate upgoing and downgoing wavefield components. The separated upgoing and downgoing wavefield components are inverse-transformed back to the time-space domain.