3D Inversion of Deep Resistivity Measurements
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Solution Overview
Problem
Current methods for generating accurate 3D models of subsurface formations using resistivity measurements are limited by the complexity of accurately determining horizontal and vertical resistivity, anisotropy, and other petrophysical properties, which affects the precision of well operations and drilling processes.
Innovation Solution
A system that applies nonlinear minimization operations, including constrained and unconstrained transformations, to generate inverted 3D models of subsurface formations, utilizing initial formation parameters and inversion variables to improve the accuracy and robustness of formation parameter determination, allowing for more precise drilling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional resistivity measurement methods are used to generate 3D formation models, then the basic formation parameters can be obtained, but the accuracy and precision of determining horizontal resistivity, vertical resistivity, and anisotropy are limited
Solution Approach 1:
The patent segments the formation model into discrete 3D pixels or volume elements, allowing independent inversion of resistivity parameters for each voxel. This segmentation enables accurate determination of horizontal and vertical resistivity components and anisotropy ratios for each pixel, resolving the measurement precision limitation while managing complexity through systematic processing of divided units
Solution Approach 2:
The patent transitions from conventional 1D or 2D resistivity interpretations to full 3D inversion, adding the vertical dimension and lateral variability simultaneously. This dimensional expansion allows simultaneous determination of horizontal resistivity, vertical resistivity, and anisotropy parameters throughout the formation volume, achieving comprehensive accurate characterization despite increased computational complexity
2Adaptability or versatility
If accurate 3D formation models with multiple formation parameters are generated, then better well operations and drilling strategies can be developed, but the computational complexity and processing requirements increase
Solution Approach 1:
The patent transforms the inversion problem by changing parameters through constrained nonlinear transformations. It applies transformation functions to map inversion variables to formation parameters (horizontal resistivity, vertical resistivity, anisotropy ratios), allowing the system to handle multiple parameters simultaneously while managing computational complexity through parameter transformation rather than direct multi-parameter inversion
Solution Approach 2:
The patent introduces transformation functions and intermediate variables as mediators between raw resistivity measurements and final formation parameters. These intermediary transformation steps decouple the complex multi-parameter inversion into manageable sequential operations, enabling versatile 3D modeling with horizontal and vertical resistivity, anisotropy, and other petrophysical properties while controlling computational complexity
Data Source
AI summary
A method includes setting a value of a formation parameter for a subsurface formation and creating an initial three-dimensional (3D) model of the subsurface formation based on the formation parameter. The method also includes applying a constrained transformation to one or more inversion variables of the initial 3D model to create a variable-constrained 3D model of the subsurface formation and applying an unconstrained minimization operation to the variable-constrained 3D model to generate a first transformed 3D model. The method also includes inverting the first transformed 3D model to generate a first inverted 3D model of the subsurface formation.