Elastostatic Modeling via Finite Difference and Virial Theorem

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Solution Overview

Problem

Current geomechanical and rock physics elastostatic modeling methods, primarily relying on the Finite Element Method (FEM), face challenges in building sophisticated meshes and solving large stiffness matrices, which impede the workflow and are unsuitable for time-independent elastostatic problems.

Innovation Solution

The method repurposes the time-domain Finite Difference Method (FDM) to solve elastostatic problems by using a standard rectangular grid and a numerical attenuation mechanism to decrease kinetic energy, ensuring potential energy approaches its minimum through the Virial Theorem, avoiding the need for meshing and matrix solves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Finite Element Method (FEM) is used to solve elastostatic boundary value problems, then solution accuracy is improved, but device complexity and ease of operation deteriorate due to sophisticated meshing requirements and large stiffness matrix solvers

Engineering Contradiction:
Improvesolution accuracyVSAvoidmeshing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical meshing system of FEM with a grid-based finite difference approach. Instead of requiring sophisticated triangular or tetrahedral mesh generation, the method uses regular Cartesian grids that can be easily generated and manipulated, substituting the complex mechanical assembly process with a simpler numerical approach.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameters of the numerical approach by switching from displacement-based FEM formulations to stress-based finite difference formulations. This parameter change allows the use of regular grids instead of complex meshes and eliminates the need to assemble and solve large global stiffness matrices, thereby reducing computational complexity while maintaining accuracy.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If Finite Element Method (FEM) is used to solve elastostatic boundary value problems, then solution accuracy is improved, but productivity deteriorates due to laborious meshing workflows and complex matrix solver algorithms

Engineering Contradiction:
Improvesolution accuracyVSAvoidworkflow efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent substitutes the labor-intensive FEM meshing workflow with an automated finite difference grid system. Regular Cartesian grids can be generated automatically without manual intervention, and the stress-based formulation eliminates the need for complex matrix assembly and solution procedures, dramatically improving workflow efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the most time-consuming aspects of FEM workflows - the mesh generation and global matrix solution steps - by using a finite difference approach that operates directly on regular grids with local stencils, thereby extracting only the essential computational core while removing productivity bottlenecks.

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If time-domain Finite Difference Method (FDM) with numerical attenuation is used to solve elastostatic problems, then productivity and ease of operation are improved, but solution accuracy may deteriorate due to energy dissipation effects

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidsolution accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs periodic application of the Virial Theorem to monitor and control energy conservation throughout the numerical attenuation process. By periodically checking the relationship between kinetic and potential energy, the method ensures that the attenuation process maintains solution accuracy while achieving the desired elastostatic state.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent implements feedback control through the Virial Theorem, which continuously monitors the energy state of the system during numerical attenuation. When the energy balance deviates from the expected relationship, the method adjusts the attenuation parameters to maintain accuracy, ensuring that productivity gains do not compromise solution precision.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3227731B1System and method for geomechanical and rock physics elastostatic modeling
Publication Date: 2020.03.18 CHEVRON USA INC
  • EP3227731B1 patent drawingFigure 1
  • EP3227731B1 patent drawingFigure 2A~2B
  • EP3227731B1 patent drawingFigure 3

AI summary

A method for geomechanical and rock physics modeling of a geologic volume of interest may include solving for the elastostatic boundary value problems using a finite-difference method which applies the Virial Theorem.