CT Image Segmentation for Rock Physics Modeling
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Solution Overview
Problem
Existing methods for estimating material properties of porous media, such as subsurface rock formations, require extensive laboratory and well measurements, which are time-consuming and costly, and do not efficiently utilize CT images for real-time analysis.
Innovation Solution
A method that involves creating three-dimensional tomographic images of rock samples, segmenting them into pore space and rock grains using gray scale thresholds, estimating porosity, and modeling petrophysical parameters to determine relationships between these parameters through statistical best fit, allowing for real-time estimation without extensive laboratory measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional thin section preparation and digitization methods are used, then measurement precision of material properties is improved, but loss of time and productivity deteriorate due to extensive laboratory preparation
Solution Approach 1:
The patent uses CT scanning to create digital 3D copies of rock samples, replacing the need for physical thin section preparation. The digital models can be repeatedly analyzed without additional sample preparation time, maintaining measurement precision while eliminating time-consuming laboratory procedures.
Solution Approach 2:
The patent replaces mechanical thin section preparation and optical microscopy with computer-based CT imaging and numerical simulation. This substitution eliminates manual preparation steps while providing equivalent or superior measurement capabilities through automated image analysis and physics-based modeling.
2Reliability
If extensive laboratory measurements are performed to establish rock physics transforms, then reliability of parameter relationships is improved, but device complexity and cost increase
Solution Approach 1:
The patent enables the rock formation sample to provide its own structural information through CT scanning. The 3D pore structure and grain architecture are directly captured from the sample itself, eliminating the need for separate laboratory measurements and complex calibration procedures to establish parameter relationships.
Solution Approach 2:
The patent extracts the essential structural information directly from CT images through image processing and segmentation. By extracting pore space, grain, and connectivity information directly from the digital model, the method eliminates the need for extensive physical measurements while maintaining reliability through direct observation of sample architecture.
3Measurement precision
If multiple three-dimensional representations are generated and averaged, then measurement precision is improved, but productivity deteriorates due to computational overhead
Solution Approach 1:
The patent performs preliminary segmentation and classification of pore space and grains from the CT image before generating multiple representations. By pre-processing the image data to identify and label different phases, the subsequent generation of multiple 3D models and their analysis becomes more efficient, maintaining precision while improving productivity.
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
Enables rapid and accurate estimation of petrophysical properties like porosity, permeability, and resistivity directly from CT images, facilitating real-time characterization of subsurface formations during drilling operations.
Implementation Method 1
devices for generating CT images of samples such as drill cuttings have become available. Such CT image generating devices (CT scanners) typically produce three-dimensional gray scale images of the samples analyzed in the scanner.
Implementation Method 2
The image is segmented into pixels each representing pore space or rock grains. a) determining an initial gray scale threshold for each of pore space and rock grain; b) allocating each pixel in the image to pore space or rock grain for each pixel meeting threshold criteria
Data Source
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AI summary
A method for estimating a relationship between physical properties of a porous material from a sample thereof includes making a three dimensional tomographic image of the sample of the material. The image is segmented into pixels each representing pore space or rock grains. The image is divided into sub-volumes. A porosity is estimated for each sub-volume. At least one petrophysical parameter is modeled from the image of each sub-volume. A relationship between the porosity and the at least one modeled petrophysical parameter is determined by, e.g., a best-fit statistical method. The relationship and the modeled petrophysical parameter for each sub-volume are stored in a computer or displayed.