Using Digital Rock Analysis to Estimate Flow Properties of Stress-Sensitive Rocks
Open Access
- Author:
- Al Balushi, Faras
- Graduate Program:
- Energy and Mineral Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 08, 2020
- Committee Members:
- Arash Dahi Taleghani, Thesis Advisor/Co-Advisor
Mort D Webster, Program Head/Chair
Gregory R King, Committee Member
Derek Elsworth, Committee Member - Keywords:
- Stress-dependent permeability
Absolute permeability
Digital rock analysis
Finite Element Analysis
Lattice Boltzmann Methods - Abstract:
- In many formations, petrophysical properties such as porosity and permeability evolve as a result of deformations caused by changes in the stress field, which could be due to injection, production or other causes. It is notable that changes in these properties like the nature of stress would be a continuous change so sporadic measurement at few stress points may not be enough to describe the whole scenario. Empirical models derived experimentally are commonly used to describe the response of absolute permeability to changes in the effective stress components. However, these models are limited to few stress components such as uniaxial stress and overburden pressure and few types of formations. Thus, quantifying and understanding the changes in absolute permeability due to changes in different combinations of effective stress components in a fast and cost-efficient manner is desired. In this study, we present a practical workflow to characterize and estimate stress-dependent permeability under any arbitrary stress configuration. An equation of state is proposed to relate the change in rock permeability due to changes in effective stress components only though the three independent strain invariants. In this study, digital rock physics, finite element analysis, and Lattice Boltzmann Methods were utilized to provide a fast estimation of the rock permeability using micro-Computed Tomography images without the need for repetitive laboratory experiments that are costly and laborious. We implemented the workflow on a high and a low permeability sandstone samples. The results show that absolute permeability decreases nonlinearly with increasing strain invariants. In addition, absolute permeability was found to be more stress-sensitive in the sample with low initial permeability. Understanding the variation in absolute permeability influenced by deformation of the microstructure due to changes in effective stress tensor assists in improving the productivity and injectivity in many subsurface engineering problems.