Nonlinear Well Log Resolution Enhancement via Modified Van Cittert Method
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Solution Overview
Problem
Existing well logging techniques, particularly linear deconvolution, fail to effectively enhance resolution in high-contrast formations and often produce unstable artifacts due to nonlinear tool responses, lacking the ability to match resolutions at preselected values like 2 ft. or 4 ft.
Innovation Solution
A modified Van Cittert nonlinear enhancement method is employed, which includes a vertical processing module for iterative 2D forward modeling and radial inversion, using relaxation factors and Gaussian filters to stabilize and match resolutions at predetermined values, avoiding the need for subsequent smoothing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear deconvolution is used to enhance resolution, then vertical resolution is improved and resolution matching at preselected values is achieved, but unacceptable artifacts are produced in high-contrast formations due to nonlinear tool response
Solution Approach 1:
The patent transitions from linear deconvolution parameters to nonlinear deconvolution parameters, specifically using iterative nonlinear techniques that adapt to the actual tool response characteristics in high-contrast formations. This involves changing the mathematical model from linear to nonlinear to match the physical reality of induction tool response, thereby eliminating artifacts while maintaining resolution enhancement and matching capabilities.
2Reliability
If nonlinear enhancement techniques are used to reduce artifacts, then robustness in high-contrast formations is improved, but instability occurs due to large corrections required in each iteration
Solution Approach 1:
The patent implements feedback mechanisms through iterative nonlinear deconvolution where each iteration uses the results from the previous iteration to adjust and refine the enhancement. The process continuously monitors convergence and adjusts correction magnitudes, applying feedback control to prevent instability while maintaining the robustness needed for high-contrast formation processing.
Solution Approach 2:
The patent applies partial corrections in each iteration rather than full corrections, using controlled adjustment factors that prevent excessive changes. This approach applies just enough correction to improve the log quality while avoiding the instability that would result from aggressive, full-strength corrections at each step.
3Reliability
If conventional nonlinear enhancement is used, then artifacts are reduced, but the ability to match resolutions at preselected fixed values is lost
Solution Approach 1:
The patent creates a universal nonlinear deconvolution framework that simultaneously achieves multiple functions: artifact reduction in high-contrast formations, resolution enhancement, and resolution matching at preselected fixed values. The methodology integrates these previously separate capabilities into a single unified process that handles all three objectives through the same nonlinear iterative algorithm with appropriate constraints.
Data Source
AI summary
A technique for processing well logs performs a nonlinear resolution enhancement of raw well logs. The nonlinear enhancement procedure uses a modified Van Cittert nonlinear enhancement technique that avoids instabilities that can arise using Van Cittert techniques. The nonlinear enhancement can provide resolution matched results at a predetermined resolution.