Angle Domain Common Image Gathers from Reverse Time Migration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current seismic data processing methods, particularly reverse time migration (RTM), are computationally intensive and struggle to accurately and efficiently compute angle domain common image gathers (ADCIG) in complex environments, such as subsalt exploration, due to instability in direction vector based methods and high computational costs of local plane wave decomposition methods.
Innovation Solution
A direction vector based method that calculates characteristic wavefields using first or second-order acoustic wave equations, decomposes wavefields into directional components centered on propagation angles, and forms ADCIG using a cross-correlation imaging condition, stabilizing the process and reducing computational costs by applying a wavefield decomposition algorithm over an angle interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direction vector based methods are used to compute ADCIG, then computational efficiency is improved, but accuracy and stability deteriorate in complex environments
Solution Approach 1:
The patent introduces characteristic wavefields as an intermediary between the seismic data and the ADCIG formation process. These characteristic wavefields are calculated using wave equation solvers and serve as a stable foundation for subsequent angle decomposition, replacing the unstable direct direction vector methods while maintaining computational efficiency through the use of predefined time steps and angle intervals.
Solution Approach 2:
The patent segments the wavefield into characteristic wavefields corresponding to different propagation directions. By decomposing the full wavefield into directional components using the characteristic wavefields, the method enables stable and efficient computation of ADCIG without requiring complex local plane wave decomposition, thus resolving the contradiction between efficiency and stability.
2Measurement precision
If local plane wave decomposition methods are used to compute ADCIG, then accuracy is improved, but computational cost increases significantly
Solution Approach 1:
Instead of performing complete local plane wave decomposition at every point, the patent applies partial decomposition using characteristic wavefields at predefined time steps and angle intervals. This partial action maintains sufficient accuracy for ADCIG formation while dramatically reducing computational cost by avoiding the exhaustive decomposition required by traditional methods.
Solution Approach 2:
The patent changes the parameter space by working in the characteristic wavefield domain rather than directly in the spatial domain. By transforming the problem into characteristic coordinates and using angle interval-based decomposition, the method achieves accurate ADCIG with reduced computational complexity compared to traditional parameter-based decomposition approaches.
3Reliability
If RTM is applied to complex environments like subsalt exploration, then imaging capability is improved, but computational intensity increases
Solution Approach 1:
The patent performs preliminary calculation of characteristic wavefields using wave equation solvers before the ADCIG formation step. By pre-computing these characteristic fields at predefined time steps and using them for subsequent angle decomposition, the method reduces the overall computational intensity of RTM in complex environments while maintaining enhanced imaging capability.
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 produces accurate and computationally affordable ADCIG, is robust for complex wavefields, and can be applied to more complex models like anisotropic and elastic propagation, while maintaining efficiency comparable to the Poynting vector method.
Implementation Method 1
applying a wavefield decomposition algorithm on the characteristic source and receiver wavefields to obtain corresponding directional source and receiver wavefields, the wavefield decomposition algorithm decomposing wavefield amplitude of a wavefield in an angle interval centered on a propagation angle of the wavefield
Implementation Method 2
forming ADCIG by applying an image condition to the obtained directional source and receiver wavefields
Data Source
AI summary
The present disclosure describes methods and systems, including computer-implemented methods, computer program products, and computer systems, for modeling angle domain common image gathers (ADCIG) from reverse time migration (RTM). One computer-implemented method includes calculating seismic source and receiver wavefields based on seismic data, calculating characteristic source and receiver wavefields from the seismic source and receiver wavefields, calculating propagation angles for the characteristic source and receiver wavefields, applying a wavefield decomposition algorithm on the characteristic source and receiver wavefields to obtain corresponding directional source and receiver wavefields, the wavefield decomposition algorithm decomposing wavefield amplitude of a wavefield in an angle interval centered on a propagation angle of the wavefield, and forming ADCIG by applying an image condition to the obtained directional source and receiver wavefields.