Ocean-Bottom Cable Seismic Multiple Attenuation via Wavefield Extrapolation
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Solution Overview
Problem
Current methods for attenuating multiple reflections in ocean bottom cable (OBC) seismic data are inadequate, as they differ significantly from towed streamer surveys, and existing Wavefield Extrapolation Multiple Modeling (WEMM) methods do not effectively account for the unique sensor configurations and source-receiver depth differences in OBC surveys.
Innovation Solution
The proposed solution involves separating the wavefield into up/down components on both the source and receiver sides, using WEMM to extrapolate and predict multiples, and then adaptively subtracting these predictions from the seismic data to isolate the primary signal, with the option to combine methods for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If WEMM is applied to predict surface multiples in OBC seismic data, then multiple attenuation is achieved, but the method must account for unique OBC sensor configurations and source-receiver depth differences that differ from streamer surveys
Solution Approach 1:
The patent applies local quality by making the wavefield extrapolation process specific to OBC geometry. The methodology uses separate up-going and down-going wavefield extrapolations tailored to the ocean-bottom cable configuration, where sources are in water and receivers are on the seabed. This localized adaptation ensures accurate multiple prediction for OBC's unique source-receiver depth differences and dual-sensor setup.
Solution Approach 2:
The patent segments the wavefield into up-going and down-going components for separate extrapolation. This segmentation allows the method to handle the complex OBC geometry by treating upward and downward propagating waves independently, then combining results to predict surface multiples accurately without being constrained by streamer survey assumptions.
2Measurement precision
If two types of sensors (hydrophones and geophones) are used in OBC surveys to capture both pressure and displacement, then data quality is improved, but the processing methodology becomes more complex compared to single-sensor streamer surveys
Solution Approach 1:
The patent achieves universality by developing a wavefield extrapolation methodology that simultaneously handles both hydrophone (pressure) and geophone (displacement) data. The up-going and down-going wavefield separation and extrapolation processes are designed to work with dual-sensor OBC configurations, making the method applicable to both sensor types without requiring separate processing streams.
Solution Approach 2:
The patent applies parameter changes by transforming the dual-sensor data into unified up-going and down-going wavefield components through extrapolation. This transformation converts the complex dual-parameter measurement (pressure and displacement) into a standardized wavefield representation that can be processed using consistent extrapolation operators, simplifying the overall processing despite the dual-sensor input.
3Loss of information
If sources and receivers are at different depths in OBC surveys, then subsurface imaging capability is improved, but existing streamer survey methods are not directly applicable
Solution Approach 1:
The patent applies preliminary action by performing up-going and down-going wavefield extrapolation before multiple subtraction. This preliminary wavefield separation and extrapolation prepares the data specifically for OBC's source-receiver depth configuration, creating accurate multiple predictions that account for the vertical separation between water-column sources and seabed receivers, enabling effective multiple attenuation tailored to this geometry.
Solution Approach 2:
The patent uses inversion by reversing the traditional streamer approach. Instead of assuming sources and receivers at similar depths (streamer model), the methodology inverts the assumption to handle sources in water and receivers on the seabed (OBC model). The wavefield extrapolation is performed in the opposite direction from conventional streamer processing, adapting the physics to match OBC's inverted source-receiver configuration.
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 effectively attenuates surface multiple reflections, enhancing the quality of seismic data by isolating the primary signal and reducing noise, thereby improving the accuracy of subsurface structure interpretation in OBC surveys.
Implementation Method 1
Wavefield Extrapolation Multiple Modeling (WEMM) to predict multiples for seismic data recorded by dual sensors on the ocean bottom cables
Implementation Method 2
separating the wavefield into up/down wavefield on the source-side, the receiver-side or both
Data Source
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AI summary
Methods for attenuating multiple reflections using Wavefield Extrapolation Multiple Modeling, wherein the wavefield is separated into up/down wavefield on either source-side or receiver-side; wherein WEMM is used to extrapolate and predict multiples, which are attenuated from OBC seismic data.