Effect of CO2 injection on the poromechanical and multiphase flow characteristics of subsurface rock

Geologic carbon storage has a great potential in reducing atmospheric CO2 emissions by permanently sequestering large volumes of carbon dioxide in reservoir formations sealed with tight rock. 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, including two-phase flow, with CO2 treatment tests conducted under high-pressure conditions. Berea sandstone is selected to represent silica-rich rock, while Apulian and Indiana limestones are chosen as calcite-rich rock. This study investigates the effect of CO2 treatment on the compressibility, time-dependent response, and relative permeability. The compressibility is measured for the selected materials and their composing minerals. By comparing pristine and CO2 treated specimens, experiments reveal that the compressibilities of sandstone, quartz, and calcite minerals do not change, while the limestone’s response can be affected by creating new connected and non-connected pores. Then, the effect of CO2 treatment on the time-dependent response is investigated. In contrast to the compressibility measurements, it is reported that the treatment significantly promotes the time-dependent behavior of the sandstone and limestones. It is argued that the mechanism for the effect of CO2 treatment is different for sandstone and limestones, where the dissolution of calcite is the main reason for the changes in the properties of the latter ones, while the generation of microcracks due to stress corrosion is the main mechanism for silica-rich rock. The hydro-mechanical-chemical constitutive model is adopted to address the coupled response of subsurface rock, with investigation of the impact of duration of CO2 injection. The importance of considering the chemical aspect in the constitutive equations is highlighted by comparing the hydro-mechanical and hydro-mechanical-chemical coupling for the porosity change. Moreover, the multiphase flow response of water and CO2 is experimentally studied with the impact of CO2 treatment. A novel method to determine the degree of saturation for the relative permeability curve is introduced, and additional measurements of the microscale properties are conducted for the capillary pressure, wettability, and surface roughness. The experiments show that CO2 treatment alters the relative permeability curve by increasing the permeability and maximum CO2 saturation for the limestones, while no significant effect is observed for the sandstone. Furthermore, the experimental techniques developed in this study are utilized for reporting the poromechanical and hydraulic properties of two shales and one granite representing the sealing layers for CO2 storage. Ultra-low permeability of the sealing formations is accurately measured in a few month-long experiments and is coupled to the mechanical and pore network characteristics of the rock. By establishing the porosity-permeability relationship, the findings reveal that the exponent value for tight rock is significantly larger than that of porous rock, which is often misused. This implies that for tight rock, a small increase in porosity can result in a considerable change in permeability, which is crucial for the sealing layers. In summary, this thesis provides a comprehensive experimental workflow aimed at characterizing the poromechanical and hydraulic response of representative rock types during CO2 injection, where the time-dependent and chemical effects are also considered.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Kim, Kiseok

Contributors dc:contributor

• Makhnenko, Roman Y
• Valocchi, Albert J
• Popovics, John S
• Olson, Scott M
• Whittaker, Steven G

• Geologic Carbon Storage
• Carbon Storage
• Poromechanics
• Poroelasticity
• Poroviscoelasticity
• Compressibility
• Permeability
• Relative permeability
• Time-dependent deformation
• Saturation
• Hydro-Mechanical-Chemical coupling
• Hydro-Mechanical coupling
• Capillary pressure
• Residual saturation
• Porosity-permeability relationship
• Calcite dissolution
• Particle rearrangement
• Stress corrosion

Statement dc:rights

• Copyright 2022 Kiseok Kim

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115940

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115940