Digital Rock Analysis REV Determination via Phase Partitioning

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Solution Overview

Problem

Current methods for determining the representative elementary volume (REV) in digital rock analysis are subjective, prone to errors, and fail to accurately characterize anisotropic and heterogeneous materials, especially in multiphase fluid flow simulations.

Innovation Solution

The system employs high-resolution focused ion beam and scanning electron microscopy coupled with high-performance computing to analyze the porosity structure of samples, using phase-based partitioning and statistical analysis of subvolume parameters to determine the REV, enabling accurate characterization of multiphase flow properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional REV determination methods are used, then the process is simpler, but the results are subjective and prone to errors

Engineering Contradiction:
ImproveREV determination accuracyVSAvoidanalysis system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates digital copies (virtual models) of rock samples through high-resolution scanning and imaging, allowing REV determination to be performed on digital representations rather than physical samples. This enables repeated, consistent analysis without subjective physical measurements, resolving the contradiction between measurement precision and complexity by automating the analysis process through computational methods.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces manual, subjective REV determination methods with automated computational algorithms that analyze digital rock models. Statistical metrics and automated classification systems substitute for human judgment, eliminating subjectivity and errors while managing complexity through software-based solutions.

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

2Measurement precision

If high-resolution microscopy and high-performance computing are used, then REV determination accuracy is improved, but the computational resources and time required increase

Engineering Contradiction:
ImproveREV determination accuracyVSAvoidanalysis time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary high-resolution scanning and digital model creation once, then reuses these digital models for multiple REV determination analyses. This preliminary action captures all necessary detail upfront, allowing subsequent statistical analyses to be performed efficiently on the existing digital data without repeated physical scanning, thus reducing overall time loss.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent analyzes multiple subvolumes and statistical metrics beyond the minimum required, using excessive computational effort to ensure robust REV determination. By performing more analyses than strictly necessary (multiple statistical tests, multiple subvolume classifications), the system achieves higher confidence and accuracy in REV identification, justifying the additional computational time through more reliable results.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If statistical analysis of multiple subvolumes is performed, then REV determination reliability is improved, but the computational complexity increases

Engineering Contradiction:
ImproveREV determination reliabilityVSAvoidanalysis method complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the digital rock model into multiple subvolumes and performs independent REV analysis on each segment. This segmentation allows statistical comparison across multiple regions, improving reliability by ensuring the REV determination is consistent throughout the entire sample rather than relying on a single potentially anomalous region.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses statistical feedback from multiple subvolume analyses to iteratively refine REV determination. By comparing results across subvolumes and using statistical metrics to guide further analysis, the system automatically adjusts and converges on the correct REV, improving reliability through self-correcting computational feedback loops.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach provides a robust and objective method for determining the REV, ensuring accurate representation of larger volumes and improved accuracy in multiphase fluid flow simulations by identifying the length scale at which distribution moments converge, thus addressing the limitations of existing methods.

Implementation Method 1

high resolution focused ion beam and scanning electron microscope

Methodology Applied
Scientific EffectFocused ion beam: Ion Beam

Implementation Method 2

high resolution focused ion beam and scanning electron microscope

Methodology Applied
Scientific EffectScanning electron microscopy: Scanning Probe Microscopy

Data Source

PatentUS9080946B2Digital rock analysis systems and methods with multiphase flow REV determination
Publication Date: 2015.07.14 HALLIBURTON ENERGY SERVICES INC
  • US9080946B2 patent drawing
  • US9080946B2 patent drawing
  • US9080946B2 patent drawing

AI summary

The pore structure of rocks and other materials can be determined through microscopy and subject to digital simulation to determine the properties of multiphase fluid flows through the material. To conserve computational resources, the simulations are preferably performed on a representative elementary volume (REV). The determination of a multiphase REV can be determined, in some method embodiments, by deriving a porosity-related parameter from a pore-matrix model of the material; determining a multiphase distribution within the material's pores; partitioning the pore-matrix model into multiple phase-matrix models; and deriving the porosity-related parameter from each phase-matrix model. The parameter's dependence on phase and saturation can then be determined and analyzed to select an appropriate REV size.