Digital Rock Image Correction for Expanded Porosity
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Solution Overview
Problem
Conventional laboratory methods for characterizing rock samples struggle to accurately determine original porosity and permeability due to deformation caused by gas expansion when samples are brought to the surface, leading to overestimation of these properties and difficulties in replicating the native state of the sample.
Innovation Solution
The method involves using high-resolution X-ray microtomography and software-based processing to identify and correct expanded porosity by 'filling in' enlarged pores with grain structures from unexpanded regions, creating a digital rock image representative of the original formation, and estimating rock properties like permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laboratory physical recompaction techniques are used, then sample deformation is addressed, but the sample cannot be returned to its original condition and measurement precision deteriorates
Solution Approach 1:
The patent creates a digital copy (virtual model) of the rock sample's pore structure through X-ray microtomography scanning, allowing analysis and measurement without physically altering the sample. This digital replica enables repeated measurements and simulations while preserving the original sample's expanded state, eliminating the need for physical recompaction that fails to restore original conditions.
Solution Approach 2:
The patent replaces mechanical physical recompaction techniques with computational methods. Instead of applying physical forces to compact the sample, the invention uses image processing algorithms and numerical simulations to analyze pore structure and estimate permeability from the digital model, thereby avoiding mechanical alterations that cannot fully restore the sample.
2Ease of operation
If rock cores are retrieved from downhole environment, then sample accessibility is improved, but gas expansion causes deformation and over-estimation of porosity and permeability
Solution Approach 1:
The patent performs X-ray microtomography scanning of the sample immediately upon retrieval from the downhole environment, before any significant deformation or gas expansion occurs. This preliminary digital documentation captures the sample's initial state, allowing later analysis to reference the original configuration before expansion artifacts develop.
Solution Approach 2:
By creating a digital twin of the sample's pore structure through high-resolution scanning, the patent preserves the original state information for analysis. The digital model can be processed to identify and correct expansion-related artifacts, separating true porosity from expansion-induced voids, thereby recovering accurate original properties without needing to physically restore the sample.
3Measurement precision
If high-resolution X-ray microtomography and software processing are used, then measurement precision is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent employs X-ray microtomography technology that serves multiple functions: it captures the sample's pore structure, identifies expanded regions, and provides data for both porosity calculation and permeability simulation. This multi-functional approach consolidates what would otherwise require separate imaging and analysis systems into a unified workflow, managing complexity through integration.
Solution Approach 2:
The software processing pipeline is designed to automatically identify expanded pore regions, segment the pore network, and compute permeability estimates without requiring extensive manual intervention or complex user configuration. The algorithms self-adjust parameters and selectively analyze regions based on detected expansion patterns, reducing the operational complexity burden on the user despite the sophisticated underlying computations.
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 allows for accurate estimation of rock properties as a function of depth, reducing errors and providing corrected porosity values that enhance hydrocarbon estimation and field reserve optimization, while minimizing financial risk.
Implementation Method 1
The sample is scanned using high resolution X-ray microtomography to produce an initial scanned image of the sample
Data Source
AI summary
Methods and systems for conditioning expanded porosity, including a method that includes creating a disconnected pore structure by reducing the pore sizes of a rock sample's scanned image, identifying expanded pores within the rock sample and generating an expanded pore image from the expanded pores. The method further includes combining the expanded pore image with the scanned image to create an expansion mask, generating a grain conditioning volume based on at least one unexpanded region of the rock sample, combining the grain conditioning volume with the expansion mask to generate a fill volume image, combining the fill volume image with the scanned image to create an unexpanded volume image, and generating and presenting to a user a formation log using a model generated based upon the unexpanded volume image.