Elastic Earth Model Perturbation Estimation in Reverse Time Migration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing seismic imaging technologies, such as reverse time migration (RTM), are limited by their acoustic wave equation approach, which fails to accurately model subsurface parameters like velocity, impedance, and density when dealing with both pressure and shear wavefields, restricting their application to real seismic data.
Innovation Solution
The implementation of an elastic Earth model equation that uses the full elastic Zoeppritz PP-amplitude versus angle equation or its approximations to generate angle gathers, allowing for the extraction of elastic model perturbations and enabling imaging of both pressure and shear wavefields, thereby overcoming the acoustic wave equation limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the acoustic wave equation is used in RTM, then the imaging process is simpler and computationally more efficient, but the accuracy of subsurface parameter modeling is reduced because it cannot account for both pressure and shear wavefields
Solution Approach 1:
The patent transitions from the acoustic wave equation to the elastic wave equation, changing the fundamental physical parameters from acoustic impedance alone to multiple elastic parameters including P-wave velocity, S-wave velocity, and density. This parameter change enables the simultaneous modeling of both pressure and shear wavefields, thereby improving subsurface parameter accuracy while maintaining computational feasibility through the use of angle gathers and perturbation theory.
2Ease of operation
If the acoustic approximation of Zoeppritz equation is used, then the processing is more straightforward, but the application is limited to acoustic or pressure waves only, restricting its use with real seismic data that includes both pressure and shear wavefields
Solution Approach 1:
The patent employs the full elastic Zoeppritz equation which serves multiple functions: it can model PP reflections, PS conversions, SP conversions, and SS reflections within a unified framework. This multi-functionality allows the same equation to handle both pressure and shear wavefields, making the processing method versatile and applicable to real seismic data while maintaining reasonable computational complexity through angle gather analysis.
Data Source
AI summary
An Earth model of a subsurface is created from acquired seismic data by migrating at least one of the incident wavefields and reflected wavefields to generate angle gathers for the seismic data and identifying for the subsurface an elastic Earth model equation for the incident wavefields and the reflected wavefields in the acquired seismic data. The elastic Earth model is a function of reflection angle between the incident wavefields and reflected wavefields and elastic parameters and is fit to the generated angle gathers through perturbation in the elastic parameters. The generated perturbations are used to create the Earth model of the subsurface.