Digital Rock Physics for Accurate Permeability Estimation
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Solution Overview
Problem
Current methods for estimating rock formation properties, such as permeability and porosity, in subsurface formations are limited by the need for extensive laboratory tests and are prone to errors due to indirect measurements and contamination, especially in complex formations like shales and tight gas sandstones.
Innovation Solution
Integration of logging tool data with digital rock physics using CT and SEM imaging to calculate porosity, absolute permeability, relative permeability, and capillary pressure, allowing for more accurate and direct estimation of rock properties by correlating in-situ fluid properties with digital rock samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive laboratory tests are conducted to measure rock properties, then measurement precision is improved, but loss of time increases significantly
Solution Approach 1:
The patent performs digital rock physics simulations and CT/SEM imaging on rock samples before conducting extensive laboratory tests. This preliminary digital characterization allows for pre-estimation of rock properties and identification of key parameters, reducing the need for time-consuming physical experiments while maintaining measurement precision.
Solution Approach 2:
The patent creates digital copies of rock samples through CT and SEM imaging, then performs virtual experiments on these digital replicas. This digital twin approach allows for rapid iteration and analysis without repeatedly handling physical samples, significantly reducing laboratory analysis time while preserving measurement accuracy.
2Device complexity
If indirect measurement methods are used to estimate rock properties, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces digital rock physics as an intermediary between simple logging tool measurements and complex laboratory analyses. The digital models serve as a bridge, translating indirect logging measurements into accurate rock property estimates through virtual experiments, thereby maintaining precision without requiring complex physical measurement systems.
Solution Approach 2:
The patent replaces complex mechanical laboratory testing systems with digital simulation systems. By substituting physical permeability and porosity measurements with digital rock physics simulations based on CT/SEM images, the system achieves comparable or superior precision while using simpler, non-invasive imaging technology.
3Measurement precision
If rock samples are retrieved for laboratory analysis, then measurement precision is improved, but contamination from non-in-situ conditions increases
Solution Approach 1:
The patent creates digital copies of rock samples through CT and SEM imaging that preserve the in-situ rock structure and properties. These digital replicas can be analyzed repeatedly without physical manipulation, eliminating contamination risks associated with sample retrieval, handling, and storage while maintaining measurement precision.
Solution Approach 2:
The patent performs digital imaging and initial analysis of rock samples immediately upon retrieval, before any potential contamination can occur. By conducting preliminary digital characterization first, the system captures the authentic in-situ state of the rock, and subsequent laboratory tests can be targeted more efficiently.
4Reliability
If controlled laboratory experiments are conducted on multiple rock samples, then reliability of rock property estimates is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The patent develops a universal digital rock physics framework that can analyze multiple rock sample types (sandstones, shales, carbonates) using the same CT/SEM imaging and simulation methodology. This multi-functional digital approach replaces the need for sample-specific laboratory protocols, improving reliability across diverse formations while simplifying operational procedures.
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 reduces the need for time-consuming laboratory analyses, enhances the accuracy of permeability and porosity estimates, and provides a more representative understanding of rock properties, especially in complex formations, by directly measuring and simulating rock properties at in-situ conditions.
Implementation Method 1
a computer tomographic (CT) scanner
Implementation Method 2
scanning electron microscope (SEM) images
Data Source
AI summary
The present invention relates to a method and system for integrating logging tool data and digital rock physics to estimate rock formation properties. A rock sample from a logging tool such as a sidewall plug or large enough cutting can be extracted by the logging tool at approximately the same well bore location that the logging tool measures fluid properties. The rock samples thus obtained is scanned using a CT scanner, scanning electron microscope or other suitable scanning device. The resulting scanned rock image can be segmented and rock properties comprising porosity, absolute permeability, relative permeability, capillary pressure and other relevant rock properties are calculated. The resulting digital calculations are integrated with logging tool data and rock property estimates to improve the accuracy and timeliness of the logging tool data.