Seismic Multiple Attenuation via Adaptive Subtraction
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Solution Overview
Problem
Marine seismic surveys face challenges in analyzing subterranean formations due to the obscuration of primary reflections by surface-related and internal multiples in seismic data, which contaminate the data and hinder accurate interpretation.
Innovation Solution
The method involves calculating predicted surface-related multiples, applying adaptive subtraction to estimate primaries, and using multiple diffraction reduction to generate final estimated multiples, which are then subtracted from the seismic data to attenuate surface-related and internal multiples, resulting in an approximation of primary reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If seismic data is collected using marine seismic surveys, then comprehensive subsurface information is obtained, but the data is contaminated by surface-related and internal multiples that obscure primary reflections
Solution Approach 1:
The patent segments the seismic wavefield into primary reflections and multiples by applying the common-shot common-receiver (CS-CR) gather organization. This segmentation allows separate processing of primaries and multiples, enabling the removal of harmful multiple reflections while preserving primary reflections for accurate subsurface imaging.
Solution Approach 2:
The patent extracts and removes multiples from the seismic data by predicting surface-related multiples using the CS-CR gathers and subtracting them from the original data. This extraction process eliminates the harmful multiples that obscure primary reflections, leaving cleaner seismic data for interpretation.
2Measurement precision
If traditional seismic data processing is used, then processing speed is maintained, but accuracy is reduced due to multiples obscuring primary reflections
Solution Approach 1:
The patent performs preliminary organization of seismic data into CS-CR gathers before multiple attenuation processing. This preliminary action structures the data in a way that facilitates efficient multiple prediction and removal, enabling accurate multiple attenuation without excessive processing complexity in subsequent steps.
Solution Approach 2:
The patent uses CS-CR gathers as an intermediary data structure that bridges the original seismic data and the final processed output. This intermediary organization enables the development of efficient algorithms for multiple attenuation while maintaining processing speed, resolving the contradiction between accuracy and complexity.
3Object-affected harmful factors
If multiple attenuation techniques are applied to remove surface-related multiples, then primary reflections become clearer, but internal multiples remain as residual contamination
Solution Approach 1:
The patent applies dynamic multiple attenuation techniques that adapt to the specific characteristics of the seismic data being processed. By using dynamic rather than static approaches, the method can more effectively distinguish between primaries and multiples across different geological conditions, reducing residual internal multiples while preserving primary reflections.
Solution Approach 2:
The patent incorporates feedback mechanisms in the multiple attenuation process where the predicted multiples are compared with actual data and the prediction is refined iteratively. This feedback approach enables more complete removal of surface-related multiples and reduces residual internal multiples by continuously improving the multiple prediction accuracy.
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 removes the contamination from surface-related and internal multiples, enhancing the clarity and accuracy of seismic data for better subterranean formation analysis.
Implementation Method 1
The seismic source control activates a seismic source, which is typically an array of source elements, such as air guns or marine vibrators, that produces acoustic signals at selected times. Each acoustic signal is a sound wave that travels down through the water and into the subterranean formation.
Implementation Method 2
At each interface between different types of rock, a portion of the sound wave may be transmitted and another portion may be reflected back into the body of water as a wavefield that propagates upward toward the water surface.
Implementation Method 3
the water surface may act as a near perfect reflector by reflecting sound waves back down toward the subterranean formation. As a result, each reflection from the water surface may generate a reverberation of multiple reflections.
Implementation Method 4
The streamers towed behind the vessel are typically elongated, cable-like structures equipped with a number of seismic receivers or multi-component sensors that detect pressure and/or particle motion wavefields associated with the wavefields reflected back into the water from the subterranean formation.
Data Source
AI summary
Systems and methods for attenuating multiples in seismic data are presented. In one aspect, predicted surface-related multiples are calculated for seismic data generated by receivers in a marine survey. Estimates of primaries and multiples may be calculated by applying adaptive subtraction to the predicted surface-related multiples. Residual multiples present in the estimated primaries may be identified using multiple diffraction reduction. The residual multiples and estimated multiples are used to generate final estimated multiples that are subtracted from the seismic data to generate primaries with attenuated multiples.