Maximal Inscribed Sphere Analysis for Rock Property Estimation

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Solution Overview

Problem

Current methods for interpreting rock formation images to infer mechanical properties are inadequate, particularly in predicting stress paths and grain crushing conditions in porous sandstones, which are crucial for reservoir behavior forecasting.

Innovation Solution

The use of morphological analysis on X-ray CT images to derive microstructural parameters such as grain size distribution and characteristic intergranular contact radius, allowing for improved prediction of failure envelopes and post-yield hardening behavior by incorporating these parameters into existing micromechanical models.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional porosity-based methods are used for mechanical property estimation, then the interpretation process is simple, but the prediction accuracy of mechanical properties and stress paths is insufficient

Engineering Contradiction:

Improveprediction accuracy of mechanical propertiesVSAvoidcomplexity of image analysis method

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The method segments the rock image into distinct components (grains, pores, contacts) and analyzes each separately. By dividing the complex rock structure into manageable segments, the method extracts specific microstructural parameters (grain size, shape, contact area) that directly control mechanical behavior, thereby improving prediction accuracy without requiring overly complex overall analysis

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method transitions from traditional 2D porosity measurements to 3D microstructural characterization using X-ray CT imaging. By adding the third dimension and analyzing volumetric properties (grain volume, pore volume, spatial distribution), the method captures the true microstructural complexity that controls mechanical behavior, significantly improving mechanical property estimation

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of information

If pore space imaging is used for analysis, then the void structure is well characterized, but the mineral grain portion information is insufficient for predicting grain crushing and compaction

Engineering Contradiction:

Improveinformation about mineral grain portionVSAvoidease of image interpretation

Core Design Contradiction:

Loss of informationVSEase of manufacture

Solution Approach 1:

Instead of analyzing only the pore space as traditional methods do, the method inverts the approach by focusing analysis on the solid mineral grain portion. By segmenting and characterizing the grains themselves (their size, shape, contact areas, and spatial arrangement), the method directly obtains the information needed to predict grain crushing and compaction behavior that was previously missing from pore-based analyses

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS9892321B2Using maximal inscribed spheres for image-based rock property estimation

Publication Date: 2018.02.13 NEW ENGLAND RES

AI summary

A method for analyzing a rock sample comprises analyzing a three dimensional image of the rock sample using maximal inscribed sphere analysis to determine proxies for at least one of grain size distribution, mean grain size and standard deviation of grain size. The proxy or proxies are used to determine at least one mechanical property of the rock formation.