Seismic Migration Post-Critical Reflection Muting
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Solution Overview
Problem
Seismic imaging through migration faces challenges with artifacts caused by post-critical energy reflections at interfaces with rapid changes in seismic wave velocity, particularly at high-contrast boundaries like salt or carbonate layers, which are difficult to remove using conventional time-consuming muting methods.
Innovation Solution
A method that involves constructing a velocity model, determining the critical angle for an interface based on seismic wave velocities, calculating the angle between the normal vector and the arrival direction vector, and attenuating the wavefield when this angle exceeds the critical angle, using a weighted approach to smoothly transition from unattenuated to attenuated portions, thereby reducing artifacts in seismic images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional muting methods are used to remove post-critical reflections, then artifacts are reduced, but processing time increases significantly
Solution Approach 1:
The patent changes the parameter space from time-domain muting to angle-domain filtering. By calculating the angle of incidence for each ray and comparing it to the critical angle, the method selectively attenuates post-critical reflections based on angular parameters rather than temporal parameters, achieving artifact removal without the computational overhead of time-domain muting
Solution Approach 2:
The patent replaces the mechanical time-domain muting process with an angular filtering mechanism. Instead of applying time-based windows or gates to mute post-critical energy, the system calculates ray angles, determines critical angles from velocity models, and applies attenuation based on angular relationships, substituting a more efficient computational approach
2Object-generated harmful factors
If time-domain muting is applied to remove post-critical energy, then artifact reduction is achieved, but data processing complexity increases
Solution Approach 1:
The patent transforms the problem from time-domain to angle-domain by introducing angular parameters (incident angle, critical angle). This parameter transformation simplifies the identification and removal of post-critical reflections, as the angular relationship provides a clear geometric criterion for distinguishing valid from invalid energy without complex time-domain analysis
Solution Approach 2:
The patent segments the wavefield into pre-critical and post-critical components based on angular criteria. By calculating the angle of incidence for each ray and comparing it to the critical angle, the method divides the energy into two distinct categories that can be processed differently, with post-critical energy being attenuated and pre-critical energy being preserved
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 artifacts from seismic images by accurately identifying and attenuating post-critical reflections, enhancing data processing efficiency and accuracy in seismic imaging.
Implementation Method 1
When the incident angle is less than the critical angle, part of the energy is reflected and part transmitted. At the critical angle, the transmitted wave travels parallel or along the interface. Beyond the critical angle, the energy is reflected.
Data Source
AI summary
A method for processing seismic data includes obtaining a velocity model, determining a critical angle for an interface represented in the velocity model based on a ratio between velocity of the seismic wave on first and second sides of the interface, determining an orientation of a normal vector extending normal to a location of the interface, determining an orientation of an arrival direction vector of a wavefield at the location of the interface, calculating an angle between the normal vector and the arrival direction vector, determining that the angle between the normal vector and the arrival direction vector is greater than the critical angle at the location, and attenuating the wavefield associated with the location in response to determining that the angle between the normal vector and the arrival direction vector is greater than the critical angle at the location.