קולוקוויום בחוג לגאופיזיקה: The coupling between formation heterogeneity, flow, and strain types in injection-induced deformation of porous media
Yaniv Edery, Technion
Zoom: https://tau-ac-il.zoom.us/j/89059154709?pwd=u4Gphpi2sUOcLmQNlI9jPzVwblPdiX.1
Abstract:
The injection of pressurized fluids into the underground, commonly utilized in industrial processes such as carbon storage, geothermal energy production, and hydraulic fracturing, can induce seismic activity and deform the porous structure of the underground rocks. While pore pressure typically induces expansion, experimental studies suggest that under confined conditions—relevant to many injection operations into aquifers—fluid injection may lead to compaction of the porous medium. However, the coupling of flow and deformation exhibits a rich, dynamic range for the deformation type that has not been previously explored in porous structures, ranging from localized compaction to dilation and fracturing.
We investigate injection-induced compaction localizations in a granular porous medium by tracking both the global and local deformation and monitoring the applied pressure and flux. For that, we developed a method to chemically sinter Poly(methyl methacrylate) (PMMA) grains to simulate rock-like conditions.
We employ refractive index-matching fluids to track the deformation by fluorescent imaging of fluorescently labeled beads that are embedded in the porous structure during the pressurized flow [1]. We find that porous structures, primarily compacted by uniform stress at the boundary, exhibit highly non-uniform deformation patterns, amounting to shear fracture and dilation due to the coupling with the flow and pressure distribution.
The results demonstrate continuous elasto-plastic compaction at the global scale, which follows the mean effective stress. Surprisingly, this global compaction is punctuated by abrupt strain localizations that couple compaction and shear. These localizations are triggered by sudden pore collapses, followed by the shearing and rearrangement of adjacent regions, primarily upstream, due to stress gradients imposed by fluid flow.
This shear-induced rearrangement temporarily reduces stiffness, driving further compaction and stiffness recovery over time. Furthermore, while the flow condition should induce 1D compaction, we observe considerable dilation transverse to the flow, which moderates the measured permeability reduction, producing a discrepancy between the stress-strain hysteresis and the stress-permeability hysteresis. We also show that under radial conditions, these compaction-dilation events may result in tensile fractures [2]. Our findings underscore the complexity and rich physical dynamics of injection-induced compaction localization, revealing the emergence of non-axial strains in what initially appears to be a one-dimensional problem.
[1] Arnold Bachrach and Yaniv Edery. Technique for studying in high resolution poromechanical deformation of a rocklike medium. Phys. Rev. E, 108(2):L022901, August 2023.
[2] Shaimaa Sulieman, Martin Stolar, Ludmila Abezgauz, Shouceng Tian, and Yaniv Edery. Investigating the permeability evolution of artificial rock during ductile and brittle deformation under pressurized flow.arXiv preprint arXiv:2309.02231, 2023.
A.B. acknowledges The Nancy and Stephen Grand Technion Energy Program (GTEP) for supporting this research. YE and AB acknowledge the support of the MOST-RIF Cyprus-Israel Scientific Research Program (grant no. 0007592). YE and ES acknowledge the support of the Israel Science Foundation (grant no. 3774/24).
מארגן האירוע: ד"ר אריאל ללוש
