Micro-CT Rock Analysis for Subterranean Formation Integrity
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Solution Overview
Problem
Subterranean formations subjected to repeated loading and unloading forces experience changes in permeability and porosity, leading to potential fracturing during oil or gas extraction processes, making it challenging to operate wells safely and efficiently.
Innovation Solution
The use of micro-computed tomography (micro-CT) and rock mechanics testing to assess the characteristics of subterranean formations by imaging rock samples before and after triaxial shear tests, allowing for the determination of permeability and porosity changes, and informing operational strategies to maintain the formation within an elastic regime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If repeated loading and unloading forces are applied during injection and depletion processes, then fluid extraction efficiency is improved, but the subterranean formation becomes prone to fracturing and permeability changes
Solution Approach 1:
The patent applies preliminary action by performing micro-CT imaging and rock mechanics testing before actual injection and depletion operations to establish baseline elastic limits and permeability characteristics. This advance characterization allows operators to set safe pressure thresholds and operational parameters that prevent formation fracturing while maintaining extraction efficiency.
Solution Approach 2:
The patent implements feedback by using micro-CT imaging to monitor pore structure changes and rock mechanics testing to measure permeability variations in real-time or near-real-time during injection and depletion cycles. This feedback loop enables dynamic adjustment of operational parameters to keep the formation within its elastic regime, preventing permanent damage while optimizing fluid extraction.
2Measurement precision
If micro-CT imaging and rock mechanics testing are performed repeatedly to monitor formation changes, then measurement precision of permeability and porosity is improved, but operational time and complexity increase
Solution Approach 1:
The patent applies copying by creating detailed digital 3D models of the pore structure from micro-CT imaging data. These digital twins can be repeatedly analyzed and simulated without requiring physical sampling or repeated imaging, allowing extensive permeability and porosity characterization to be performed on computational copies rather than requiring continuous physical measurement of the actual formation.
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 enables safer, more reliable, and efficient well operations by predicting and mitigating permeability and porosity changes, reducing the likelihood of fracturing and ensuring continuous fluid flow.
Implementation Method 1
a sample of a subterranean formation is imaged using a micro-CT scanner to determine the characteristics of the pores and pore throats in the sample
Implementation Method 2
several non-destructive triaxial shear tests can be performed on the sample in a sequence. During each triaxial shear test, a triaxial load force can be applied to the sample for a period of time and subsequently removed from the sample
Implementation Method 3
portions of the subterranean formation may be subjected to loading forces during an injection process. As another example, portions of the subterranean formation may be subjected to unloading forces during a depletion process. Repeated loading and unloading forces can lead to increases and decreases in the effective stress in the poroelastic media of the subterranean formation
Data Source
AI summary
A computer system obtains a first set of micro-computed tomography (micro-CT) data representing a rock sample obtained from a subterranean formation that includes gas-bearing sandstone. The system obtains a plurality of second sets of micro-CT data in a sequence, each representing the rock sample after a performance of a corresponding triaxial shear test on the rock sample. Performing each triaxial shear test includes applying a triaxial load force to the rock sample, and removing the triaxial load force from the rock sample. The system estimates, based on the first micro-CT data and the plurality of second sets of micro-CT data, one or more characteristics of the underground formation, including a permeability of the underground formation and/or a porosity of the underground formation. The system causes one or more resource extraction operations to be performed on the underground formation based on the one or more characteristics of the underground formation.