Research

• Geomechanical Property Characterization
• Effect of CO2 Injection on the Poromechanical Response of Sedimentary Rocks
• Caprock Response for Subsurface Storage
• Self-Healing Response of Clay-Rich Mudrocks
• Geobarrier
• Serpentinization and Natural Hydrogen
• Fiber Optics Sensing
• Temporary Cement Plugs for Natural Gas Storage
• Multiphase Flow Response
• CO2 Enhanced Oil Recovery in Shale Reservoirs

We conduct geomechanical property characterization across a wide range of geomaterials, from high-permeability reservoir rocks to ultra-tight mudrocks and caprocks. Our laboratory measures compressibility, elastic and inelastic deformation, strength, permeability, and coupled hydro-mechanical parameters using triaxial, oedometer, core-flooding, and innovative experimental techniques. We measure drained and undrained responses, Biot coefficient, stress-dependent poromechanical properties, and time-dependent response. Based on these measurements, we establish porosity–permeability relationships and constitutive relationships, supporting applications in geoenergy systems.

Publications

• Kim, K., Espinoza, D. N. (2025). Determination of the Biot Coefficient and Permeability of Tight Rocks through Analysis of Time-dependent Partially Drained Response. Rock Mechanics and Rock Engineering, 1-23.
• Kim, K., Makhnenko, R. Y. (2020). Coupling between poromechanical behavior and fluid flow in tight rock. Transport in Porous Media, 135(2), 487-512.

During CO2 injection, multi-physical processes occur, affecting the mechanical stresses, pore pressures, temperature, and chemistry of the participating subsurface rocks and pore fluids. These processes are coupled, meaning that changes in each aspect do impact the others mutually. Thus, the interdependent factors need to be understood as a combined system, while it should also incorporate the time-dependent response, as CO2 is projected to be stored for thousands of years. Experimental techniques are introduced to characterize the poroviscoelastic and hydraulic behavior of reservoir rock with CO2 treatment tests conducted under high-pressure conditions. The hydro-mechanical-chemical constitutive model is adopted to address the coupled response of subsurface rock, with additional studies to investigate the impact of the duration of CO2 injection. The experimental techniques developed in this study are utilized for reporting the poromechanical and hydraulic properties of various sedimentary rocks.

Publications

• Kim, H., Kim, K., Makhnenko, R. Y. (2025). Hydro‐mechanical‐chemical behavior of sedimentary rock during CO2 injection. Journal of Geophysical Research: Solid Earth, 130(12), e2025JB032279.
• Kim, K., Makhnenko, R. Y. (2022). Short-and long-term responses of reservoir rock induced by CO2 injection. Rock Mechanics and Rock Engineering, 55(11), 6605-6625.
• Kim, K., Makhnenko, R. Y. (2021). Changes in rock matrix compressibility during deep CO2 storage. Greenhouse Gases: Science and Technology, 11(5), 954-973.
• Tarokh, A., Makhnenko, R. Y., Kim, K., Zhu, X., Popovics, J. S., Segvic, B., Sweet, D. E. (2020). Influence of CO2 injection on the poromechanical response of Berea sandstone. International Journal of Greenhouse Gas Control, 95, 102959.
• Kim, K., Vilarrasa, V., Makhnenko, R. Y. (2018). CO2 injection effect on geomechanical and flow properties of calcite-rich reservoirs. Fluids, 3(3), 66.

Coupling Geomechanical–Breakthrough Behavior

Caprock integrity during gas injection is governed by a strongly coupled geomechanical–breakthrough process, yet deformation and fluid breakthrough are often treated as separate problems. This study aims to establish a fundamental understanding of the coupled process by directly relating short- and long-term deformation, porosity evolution, and permeability change to fluid breakthrough behavior. The work explicitly evaluates the roles of stress history (overconsolidation ratio and loading path), pore-fluid chemistry (oil versus brine systems), and injected gas type (CO2, H2, CH4) on time-dependent deformation, strength, and permeability evolution. The objective is to resolve how stress history and fluid–rock interactions control the hydromechanical response across the breakthrough transition in clay-rich caprocks and shales.

Publications

• Park, S., Choi, H., Kim, K. (2026). Pore Fluid Effects on the Consolidation and Creep Behavior of Clay-Rich Mudrocks: Experimental Study on Brine/Oil Saturated Kaolinite. (Under Review).
• Park, S., Park, H., Choi, H., Kim, K. (2026). The Effect of Stress History on the Hydraulic Properties and Geomechanical Behavior of Caprock During CO2 Breakthrough. (Under Review).

Fractures in clay-rich geomaterials compromise the long-term performance of engineered barriers and natural seals in both civil infrastructure and subsurface energy systems. Yet many of these materials possess an intrinsic capacity for self-healing—fractures close over time through swelling, particle disintegration, and mechanical re-bonding. The mechanisms driving this process remain poorly understood, particularly under varying stress, saturation, and fluid conditions. A multiscale understanding – linking micro-scale processes to bulk mechanical and hydraulic recovery – is essential but remains undeveloped. This project aims to develop a predictive framework for fracture self-healing in clay-rich materials by integrating multiscale experiments with constitutive modeling.

Publications

• Park, S., Bakeshova, A., Kim, K. (2026). Characterizing Permeability Evolution During Self-Sealing in Kaolinite Mudrocks Using a Bi-Exponential Model. (Under Review).
• Bakeshova, A., Park, S., Meehan, N. D., Kim, K. (2026). Self-Sealing Response in Kaolinite Mudrock Fractures: Implications for CO2 Storage and Unconventional Reservoirs. (Under Review).

This study explores engineered precipitation-induced sealing barriers as an alternative strategy. Although precipitation has traditionally been treated as an operational impairment because it reduces permeability and restricts flow, it can instead be used as a controllable mechanism to deliberately occlude pore space and construct low-permeability barriers for subsurface containment. By separately injecting two incompatible ionic solutions that precipitate upon contact, in-situ mineral formation can be localized within a designed mixing zone, producing a low-permeability geo-barrier.
The central research question is how the coupled reaction–transport–poromechanical processes control the formation rate, thickness, hydraulic conductivity, and long-term integrity of the precipitation layer. The goal is to establish predictive relationships between injection conditions and geobarrier properties, enabling design criteria for durable engineered geo-barriers.

Publications

• Kim, D., Awarke, M., Younis, R., Kim, K. (2026). Spatiotemporal Dynamics of Geo-barrier Formation: Permeability and Thickness Evolution under Transverse Mixing and Precipitation. (Under Review).
• Cao, W., Younis, R. M., Kim, K., Lu, J. (2025). Structure and permeability of Barite precipitation layers formed by transverse mixing in Berea sandstone: Direct observations and modeling. Geophysical Research Letters, 52(23).

How does serpentinization affect the poromechanical properties of olivine-rich rocks?

Serpentinization is expected to modify the poromechanical properties of olivine-rich ultramafic rocks through coupled hydration reactions, solid volume expansion, and fluid–rock interaction. This reaction generates hydrogen while progressively altering stiffness, strength, pore structure, and fracture connectivity. Such reaction-driven rock-matrix evolution can change effective stress response, permeability structure, and crack development, with important consequences for fluid transport and deformation in subduction environments.
This study seeks to systematically investigate how serpentinization controls the poromechanical behavior of olivine-rich rocks by quantifying reaction-induced changes in elastic properties, compressibility, porosity, permeability, and fracture networks. Laboratory experiments are designed to simulate serpentinization under controlled temperature, pressure, and fluid conditions. Multiscale mechanical/flow testing and high-resolution imaging are used to track the coupled evolution of deformation and pore structure as reaction progresses.
The objective is to establish a framework that links serpentinization extent to evolving hydromechanical properties, and to clarify how reaction-driven microstructural changes influence fluid migration and poromechanical response in ultramafic rocks.

Publications

• Lawal, U., Kim, K. (2026). Poromechanical and Crack Evolution of Olivine Rich Rock During Serpentinization. (Under Review).