TTI Seismic Data Analysis Using Simultaneous Inversion
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Solution Overview
Problem
Accurate analysis of seismic data in anisotropic media, such as Tilted Transversely Isotropic (TTI) formations, is challenging due to directional dependence on wave propagation and poor data quality, leading to errors in estimating anisotropic parameters.
Innovation Solution
The method involves simultaneous inversion of P-wave velocity (V0) and Thomsen parameters (ε and δ) using a Very Fast Simulated Annealing (VFSA) technique, which processes walkaway VSP data to determine optimal values for a TTI model, improving seismic data processing and reducing errors in anisotropic media analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional seismic data processing methods are used in anisotropic media, then the processing is simpler, but the accuracy of anisotropic parameter estimation deteriorates
Solution Approach 1:
The patent transforms the complex anisotropic inversion problem into a simpler isotropic velocity analysis problem by changing the parameter space. Specifically, it uses coordinate transformation and parameter substitution to convert TTI parameter estimation into effective velocity analysis, which can be solved using well-established isotropic methods. This resolves the contradiction by maintaining high measurement precision through parameter transformation while avoiding the complexity of direct anisotropic inversion.
Solution Approach 2:
The patent replaces the complex mechanical inversion process with a more efficient mathematical transformation approach. Instead of directly inverting anisotropic parameters through complex optimization algorithms, it substitutes the problem with velocity analysis in transformed coordinates, utilizing standard seismic processing techniques. This substitution maintains accuracy while significantly reducing computational complexity.
2Measurement precision
If walkaway VSP survey is used to determine anisotropic parameters, then direct measurement is possible, but data quality is poor leading to estimation errors
Solution Approach 1:
The patent introduces an intermediary transformation step between raw VSP data and final anisotropic parameter estimation. By using coordinate transformation and effective velocity analysis as an intermediate process, it converts poor-quality direct measurements into more reliable parameter estimates. This intermediary process filters out data quality issues while preserving the essential anisotropic information.
Solution Approach 2:
The patent implements an iterative feedback mechanism where initial velocity models are refined through repeated analysis of VSP data. The process uses feedback from velocity analysis to progressively improve parameter estimates, allowing the system to overcome initial data quality limitations through iterative refinement and convergence to accurate anisotropic parameters.
3Measurement precision
If TTI model analysis is performed in dipping formations, then accurate subsurface imaging is achieved, but the analysis becomes computationally complex
Solution Approach 1:
The patent segments the complex TTI analysis problem into manageable components by separating vertical and horizontal velocity analysis. It divides the dipping formation analysis into stacked velocity analysis segments that can be processed independently and then combined. This segmentation maintains imaging accuracy for dipping formations while reducing overall computational complexity through modular processing.
Solution Approach 2:
The patent adds a transformation dimension to the analysis by introducing coordinate system changes and effective velocity concepts. Instead of directly analyzing TTI parameters in the original coordinate system, it transforms the problem into a different dimensional space where standard velocity analysis techniques apply. This dimensional transformation simplifies the analysis while preserving the accuracy needed for dipping formation imaging.
Data Source
AI summary
At least some of the disclosed systems and methods employ one or more seismic receivers that gather seismic data from a plurality of positions in a borehole that penetrates a formation. Further, at least some of the disclosed systems and methods employ a memory to store the gathered seismic data. Further, at least some of the disclosed systems and methods employ logic that inverts the seismic data for simultaneous determination of asymmetric axis velocity (V0) and Thomsen parameters, epsilon (ε) and delta (δ), in a tilted transversely isotropic (TTI) model.