Safe CO2 Research Articles

Environmentally friendly production of petroleum systems with high CO2 content

Natural gas hydrates represents a huge source of energy. At the same time substantial leakages of natural gas from hydrates contributes significantly to climate changes. One of the most important reasons for these natural gas fluxes is leakage of seawater in to the hydrates from seafloor, through fracture systems. Hydrate dissociates if surrounding seawater is less than hydrate stability limit. Another interesting aspect of natural gas hydrates is the potential for safe CO2 storage. These different aspects of hydrates in natural sediments put demands on thermodynamic models. In addition to accurate description of pressure temperature hydrate stability there also a need to describe hydrate dissociation in concentration gradients towards surrounding water or surrounding gas as two examples. In this work we present new experimental data and an extensive thermodynamic model for hydrate. In contrast to conventional thermodynamic models for hydrate the model is consistent since all thermodynamic properties are derived from the Gibbs free energy. In this work we examine mixtures of CH4, C2H6, N2, CO2 from the China Sea and some synthetic mixtures, using this model. Maximum CO2 content in these mixtures are 60 mol% and the rest is dominated by CH4. Agreement between experimental data and model calculations are generally good and average deviations are below 5.5% for all the systems and conditions examined. Another aspect of the model is the ability for incorporation of effects of mineral surfaces. Specifically it is illustrated that adsorption of water on rust dominates liquid water drop out from gas as compared to water dew-point. Production of natural gas with such high CO2 content requires a strategy for CO2 separation and storage. It is proposed that the CH4 is separated from the C2H6, CO2 and N2 and cracked to H2 and CO2 using steam. Thermodynamic analysis indicates a significant potential for safe CO2 storage in natural gas hydrate and H2 as the only export product.

Molecular insights into the synergistic inhibition mechanisms of antifreeze protein and methanol on carbon dioxide hydrate growth

The formation of CO2 hydrates during CO2 transportation and deep-sea injection poses a significant risk of pipeline blockage. Combining kinetic (KHIs) and thermodynamic hydrate inhibitors (THIs) serves as a promising efficient and economical strategy to mitigate this issue, whose performance and microscopic mechanisms yet are still poorly understood. This study employs molecular dynamics simulations to explore the effects of the combination of winter flounder antifreeze protein (wf-AFP) as a KHI and methanol as a THI on CO2 hydrate growth. We find that methanol and wf-AFP exhibit an intriguing synergistic inhibition performance on hydrate growth. In the AFP-only system, AFP serves as a spatial hindrance near the hydrate growth interface. However, in the AFP + methanol system, AFP changes its position due to the attractive force of methanol. Part of the AFP fragment remains on the hydrate interface, while the rest surrounds the CO2 droplet. Methanol, in addition to disrupting the water structure, combines with AFP to act as a double barrier to CO2 dissolution into the aqueous solution, thereby significantly reducing the gas source for hydrate growth. These findings provide molecular-level insights into hydrate inhibition mechanisms and guide the design of efficient inhibitors for safe CO2 transportation and injection.

Integrated battery thermal management and CO2 control in electric buses using recirculated air and waste heat recovery

In recent years, electric vehicles (EVs) have significantly progressed due to their environmental protection and energy-saving advantages. However, maintaining indoor thermal comfort and effective battery thermal management are critical considerations for EVs. Unlike conventional vehicles, EVs cannot use waste heat and depend on heat pump systems for winter heating and summer cooling. This research proposes a novel system to reduce the energy consumption of heat pump systems by using recirculated air while addressing the challenges of battery temperature management and maintaining safe CO2 concentrations in the cabin. The primary objectives of this research are threefold: first, to ensure passenger comfort through an integrated approach that includes cabin CO2 concentration safety; second, to recover heat from recirculated cabin air to save energy and control battery temperature; and third, to comprehensively analyze the performance of the Electric Vehicle Thermal Management System (EVTMS) using precise Computational Fluid Dynamics (CFD) analysis and mathematical modeling. This study will significantly enhance the understanding of energy consumption related to CO2 concentration control; an aspect previously overlooked in the literature. It will develop a battery temperature management strategy that leverages bus exhaust heat. These contributions will aid in achieving both passenger comfort and battery stability in electric buses, providing practical insights for the design and optimization of thermal management systems for future electric buses.

Theory and analytical solutions to wellbore problems with hardening/softening Drucker-Prager models

Recognizing and quantifying the elasto-plastic nature of underground formations is critical for various subsurface operations such as drilling, stimulation, production, injection, and storage. In the case of geological CO2 storage, for instance, it is key to identify storage sites characteristics and pumping parameters that lead to safe and perennial CO2 trapping. In this work, we investigate different rock hardening/softening behaviors with the Drucker-Prager model: cohesion hardening/softening, friction hardening/softening, and their combination, jointed hardening/softening. Our focus is to solve the elasto-plastic deformation analytically in the vicinity of a wellbore. The three hardening/softening formulations predict different mechanical responses and stress-paths for solving the same wellbore problem with excavation. The analytical solutions for 2D axisymmetric problems with different hardening laws are provided in this study and verified with corresponding numerical results. This approach can be used to interpret field observations and calibrate experimental data with more comprehensive models. These new laws are implemented and benchmarked in GEOS, an open-source advanced numerical simulator of subsurface formations. This study enhances our understanding of subsurface rock's elasto-plastic behavior and offer analytical references for interpretating experimental measurements and developing numerical simulations for solving wellbore problems.

Comprehensive Measurement, Monitoring, Verification Planning Enables Safe CO2 Storage, Risk Reduction, and Operating Cost Optimisation

Comprehensive Measurement, Monitoring, Verification Planning Enables Safe CO2 Storage, Risk Reduction, and Operating Cost Optimisation

Strategies for CO2 Laser Use in Laryngeal Microsurgery: A Systematic Review.

We aim to systematically review the literature addressing perioperative practices for optimal use of the CO2 laser in laryngeal transoral laser microsurgery (TOLMS), with a focus on safety. A systematic review of publications indexed in Medline, Embase, and EBM reviews-Cochrane Central Register of Controlled Trials which evaluated perioperative strategies for the use of CO2 laser in laryngeal TOLMS was conducted. Records obtained from the search strategy were assessed for eligibility in a 2-step process by 2 independent researchers using the Covidence software. Among 2143 identified records, 103 were included in this study. The majority of studies (n = 25) focused on the use of the CO2 laser in oncologic resection, while 20 addressed the treatment of vocal cord paralysis, 16 discussed the treatment of pediatric or congenital pathologies, 11 detailed the management of benign lesions, and 31 studies tackled other surgical indications. Strategies for safe CO2 TOLMS were highly heterogeneous across studies and included preoperative measures (ie, related to the environment, staff preparation, patient protection, and ventilation), intraoperative precautions (ie, protection of nontarget structures, technical considerations, topical and systemic medications), and postoperative strategies (ie, related to airway protection, oral intake, vocal rest, hospitalization duration, drug regimen, and consultant follow-up). The results provided in this study can be used as a framework to guide the creation of laser safety protocols across institutions, guide quality improvement initiatives, the development of simulation training activities, and as a tool to facilitate resident teaching and skill assessment.

Reservoir Static Modelling towards Safe CO2 Storage in Depleted Oil Reservoirs of ‘CRK’ Field, Niger Delta, Nigeria

Geological carbon storage (GCS) is gradually gaining acceptance as the technology of highest repute for the mitigation against greenhouse gas effect. This involves the injection and long-term or permanent storage of carbon dioxide (CO2) in subsurface geological formations. The development of a robust 3D reservoir model then becomes necessary to understand the facies changes and the petrophysical properties distribution of candidate CO2 storage reservoirs. This study attempts the use of static modelling technique to investigate the depleted oil and gas reservoirs of ‘CRK’ field in the Niger Delta sedimentary Basin as a potential CO2 storage site. Using an integrated approach of 3D seismic and a suit of well logs from the study area, two reservoir sands (D10C0 and D6200) were mapped. 3D static modelling of discrete and continuous property distribution of the reservoirs revealed the reservoirs are composed majorly of clean sands with water saturation ranging from 8 to 75%. The average porosity and permeability values are between 20 to 29% and 250 to 890mD respectively. A theoretical storage capacity of 24.85Mt is estimated for the two reservoirs combined, while the median effective storage capacity is 6.22Mt. Comparison of the results obtained in the study with recommended standard values show the reservoirs are suitable for CO2 storage. The property models constructed can serve as primary input for dynamic simulation of the oilfield in future studies.

Impact of CO2 sequestration on pressure systems in saline aquifer: Simulation of differential pressure evolution in the caprock-reservoir

CO2 sequestration in the saline aquifer is one of the most promising means of geological sequestration, and the realization of safe CO2 sequestration without leakage is the common goal of sequestration projects. Mature continental sedimentary basins typically have a long drilling and production history, and several wellbores inevitably penetrate the saline aquifer. These wellbores have been identified as risky locations for CO2 leakage. Scale-up CO2 injection can cause large-scale perturbations to the saline aquifer pressure system, affecting the sealing integrity of wells within the sequestration site. Considering that differential pressure is a key driver of wellbore leakage, this paper establishes and validates a three-dimensional cap-reservoir model to simulate the evolution of the differential pressure between the cap-reservoir due to CO2 sequestration. The simulation results show significant differences in the magnitude and rate of pressure buildup in the cap and reservoir during injection and in the rate of overpressure dissipation after stopping injection. These differences caused the dynamic evolution of the interlayer pressure difference. They formed peaks in the injection and stopping stages, and the peak in the injection stage was higher than in the stopping stage. The peak decreases as an exponential function with increasing distance from the injection well. In the constant rate injection mode, the peak rises linearly with increasing injection rate, and the effect of injection temperature on the peak can be neglected. A sensitivity analysis of reservoir hydrogeological parameters was done. From the perspective of controlling differential pressure, an ideal saline aquifer should be characterized by deep burial, low salinity, high permeability, and large effective pore space. This study is significant for CO2 sequestration site optimization and CO2 leakage risk control.

Potential secondary seals within overburden: Observation from the CO2 storage sites Aurora and Smeaheia, northern North Sea

This study evaluates potential secondary seals within the overburden in two CO2 storage sites, Aurora and Smeaheia within the Horda Platform area, of the northern North Sea. Secondary sealing intervals provide for safe and reliable CO2 storage as they prevent injected fluids from migrating into the atmosphere in the case of primary seal failure. This study analyzes the possible fate of the CO2 plume in the case of primary seal failure for the Aurora and Smeaheia CO2 storage sites by evaluating the secondary caprock and sealing potential of polygonal fault systems within the overburden intervals using structural reliability methods. Our findings suggest that a ductile secondary caprock is present in the overburden intervals of the storage sites, which could act as a secondary seal in the case of primary seal failure. The trapped hydrocarbon leaked from the Troll field within this ductile unit indicating a good secondary sealing potential. The study also reveals the presence of polygonal fault systems in the entire study area, but their frequency and orientation vary between layers. However, polygonal fault systems are not structurally stable, posing a risk of fault-parallel flow within the overburden interval. Nonetheless, the ductile clay-rich secondary caprock provides a seal for the polygonal fault systems within the interval. Due to either erosion or non-deposition, the ductile rock interval is not present in the east of the study area. As such, the critical risk for the Alpha structure in the Smeaheia injection site is the Vette fault and the efficiency of the primary Draupne caprock. Moreover, the crucial factor in the western Aurora site is the connectivity between the depleted Troll reservoirs and the CO2-injected pressurized reservoirs underneath. Based on our qualitative assessment, it is concluded that the overburden interval in the Horda Platform has adequate secondary sealing potential to hold and accumulate CO2 in the case of primary seal failure. Still, further numerical simulations are recommended to quantify our findings for both the Aurora and Smeaheia sites.

Solvent-Free Method for Masking the Bitter Taste of Azithromycin Dihydrate Using Supercritical Fluid Technology

ABSTRACT Introduction and purpose The unpleasant extremely bitter taste of the orally administered broad-spectrum antibiotic azithromycin decreases patient compliance, especially in pediatrics. This issue can be overcome by decreasing drug interaction with the tasting buds using insoluble polymers at salivary pH (6.8 -7.4), like the cationic polymer Eudragit EPO. Supercritical fluid technology is a green synthesis method for preparing pharmaceutical preparations that replace organic solvents with safe supercritical CO2. This study aimed to mask the bitter taste of azithromycin using the supercritical fluid method and a pH-sensitive Eudragit EPO polymer. Methods: A foaming process was investigated for preparing a formulation (TEST), which comprises treating the polymer with supercritical carbon dioxide (CO2) fluid to prepare a taste-masked dosage form without employing organic solvents or flavors. Results: The use of the supercritical technique at 40 °C and 10 MPa for two hours allowed the manufacturing of solvent-free polymeric foam with azithromycin dispersions; the average calculated percentage of apparent volume change was 62.5 ± 5.9% with an average pore diameter of 34.879 Å. The formulated sample showed low drug release in simulated salivary fluid while keeping its crystalline nature. Moreover, clinical studies on healthy subjects showed that the formula successfully masked azithromycin's bitter taste. Conclusions: Overall, it has been shown herein that the supercritical fluid technology foaming method is promising in masking the bitter taste of bitter ingredients.

Assessing the hidden dangers of volcanic CO2 exposure: a critical review of health impacts.

Volcanic eruptions pose significant health risks to inhabitants of affected regions, with volcanic gases, including carbon dioxide (CO2), being a notable concern. This review examines the implications of long-term exposure to volcanic CO2 emissions on public health, highlighting the shift in understanding from acute to chronic health effects. Recent studies have underscored the need to reevaluate the adverse health impacts of CO2 beyond acute toxicity symptoms. While previous guidelines deemed an indoor (residential) acceptable long-term exposure range (ALTER) of ≤3,000 parts per million (ppm) in residential housing areas, emerging evidence suggests that even concentrations within the range of 3,000 to 1,000 ppm may induce deleterious health effects. International agencies now advocate for lower safe indoor CO2 levels (600-1,000 ppm), necessitating a reassessment of public health strategies in volcanic areas. This review argues for increased awareness among local and public health authorities about the chronic toxicity of CO2 exposure and emphasizes the importance of safeguarding populations from the adverse health effects induced by CO2 exposure.

A flashing flow model for the rapid depressurization of [formula omitted] in a pipe accounting for bubble nucleation and growth

Flashing flow is encountered in many industrial systems involving nozzles, valves and decompression of vessels and pipes. In the context of CO2 capture and storage (CCS), the design of safe and efficient CO2 transportation systems requires accurate flashing models, e.g., for safety analysis of pipe fractures and to predict the mass flow through relief valves. We propose a homogeneous flashing model (HFM) for flashing flow accounting for the underlying physical phenomena of the phase change: bubble nucleation, coalescence, break-up and growth. Homogeneous nucleation is modeled using classical nucleation theory and heterogeneous nucleation is approximated with constant rates of bubble creation and mass transfer from liquid to vapor. The flashing flow model is fitted for CO2 pipe depressurization data at various initial conditions. We find that the same, constant model parameters can be applied for the whole set of depressurization cases considered, as opposed to the conventional homogeneous relaxation model which typically is tuned on a case-by-case basis. For depressurization paths where the fluid state passes close to the critical point, we demonstrate that an accurate description of the flashing process along the length of the pipe can only be achieved when both homogeneous and heterogeneous nucleation are accounted for.

In situ carbon storage potential in a buried volcano

Abstract In situ mineral carbonation in porous and permeable mafic and ultramafic volcanic rocks is proposed to be a promising process that can contribute toward safe and permanent CO2 sequestration. Here, we investigated a partially buried Late Cretaceous composite volcano located offshore the central West Iberian margin as a proxy for potential in situ mineral carbonation in volcanic edifices on continental margins worldwide. Based on seismic data, geochemistry, and petrophysical properties, deterministic scenarios for permanent carbon storage were estimated. Overall analysis of the nature of the volcano and its internal architecture revealed that this single edifice has the potential to store 1.2–8.6 Gt CO2 in newly formed carbonate mineral assemblages. Results suggest that ancient, buried volcanoes on continental margins constitute auspicious sites for safe carbon storage, with a total storage capacity of hundreds of gigatonnes of CO2.

Carbon Capture, Utilization, and Storage in Saline Aquifers: Subsurface Policies, Development Plans, Well Control Strategies and Optimization Approaches—A Review

To mitigate dangerous climate change effects, the 195 countries that signed the 2015 Paris Agreement agreed to “keep the increase in average global surface temperature below 2 °C and limit the increase to 1.5 °C” by reducing carbon emissions. One promising option for reducing carbon emissions is the deployment of carbon capture, utilization, and storage technologies (CCUS) to achieve climate goals. However, for large-scale deployment of underground carbon storage, it is essential to develop technically sound, safe, and cost-effective CO2 injection and well control strategies. This involves sophisticated balancing of various factors such as subsurface engineering policies, technical constraints, and economic trade-offs. Optimization techniques are the best tools to manage this complexity and ensure that CCUS projects are economically viable while maintaining safety and environmental standards. This work reviews thoroughly and critically carbon storage studies, along with the optimization of CO2 injection and well control strategies in saline aquifers. The result of this review provides the foundation for carbon storage by outlining the key subsurface policies and the application of these policies in carbon storage development plans. It also focusses on examining applied optimization techniques to develop CO2 injection and well control strategies in saline aquifers, providing insights for future work and commercial CCUS applications.

CO2 Viscosification for Mobility Alteration in Improved Oil Recovery and CO2 Sequestration

Recently there have been significant advances in the viscosification of CO2 using a low concentration of oligomers. The new engineered molecules do not adsorb onto rock. This paper studies the effects of different CO2-enhanced viscosity levels in subsurface aquifers and reservoirs. The study was conducted using numerical modeling and simulation tools in homogeneous, heterogenous, fractured, and unfractured media. The viscosity enhancement of CO2 varied from 2- to 20-fold. The simulations included homogeneous, layered, and fractured domains in 2D and in 3D for improved oil recovery. The results showed that in unfractured, homogenous, and layered media, a 10-fold viscosity increase leads to significant increases in oil recovery. In a fractured medium with a highly connected fracture network, a 20-fold viscosity enhancement may have a considerable effect in delaying breakthrough and improving oil recovery. Simulations were performed in a compositional three-phase flow based on higher-order discretization. The algorithm included Fickian diffusion, which may add to oil recovery performance when there is a sufficient surface area between the CO2-rich phase and the oil phase. In CO2 sequestration, an increase in the viscosity of CO2 and consequent mobility control promotes CO2 dissolution in the aqueous phase. Due to the increase in the density of the aqueous phase from CO2 dissolution, the CO2 is carried away from the cap rock to the bottom of the formation. This work is of particular importance in improved oil recovery and in safe CO2 sequestration due to solubility trapping and mitigation of pressure increase. The higher-order numerical scheme used in this simulation guarantees a level of accuracy not obtained in traditional simulators.

Coupling Amino Acid with THF for the Synergistic Promotion of CO2 Hydrate Micro Kinetics: Implication for Hydrate-Based CO2 Sequestration

CO2 capture and sequestration are broadly recognized as the most effective technology for reducing CO2 emissions and mitigating global climate change. In this regard, hydrate-based CO2 sequestration (HBCS) has been proposed as an effective method for long-term safe and stable CO2 sequestration. It is a promising technology for reducing the concentration of CO2 in the atmosphere and achieving carbon neutrality. However, one major challenge related to HBCS technology is the lack of understanding of how to improve the formation kinetics of CO2 hydrate effectively. Herein, in this study, we identified the synergistic promotion effect on CO2 hydrate formation when a low-dose thermodynamic promoter (tetrahydrofuran, THF) is coupled with an environment-friendly kinetic promoter (l-methionine, l-Met). Based on the kinetic experiments and the morphological observation, 0.6 mol % THF coupled with 0.1 wt %l-Met yields the optimal CO2 gas uptake. In situ Raman spectra reveal the mechanism of the observed two-step growth behavior at the molecular level, where low-dose THF promotes the initial CO2-THF sII hydrate nucleation and growth in the solution and l-Met promotes the subsequent CO2 sI hydrate growth along the surface of the reactor. Our study unveils the underlying synergistic mechanism when thermodynamic and kinetic promoters are coupled for CO2 hydrate formation. The results provide guidance for the identification and use of novel bio-friendly thermodynamic and kinetic promoters and are beneficial to a series of sustainable hydrate-based technologies when fast CO2 formation is required.

Safe CO2 threshold limits for indoor long-range airborne transmission control of COVID-19

CO2-based infection risk monitoring is highly recommended during the current COVID-19 pandemic. However, the CO2 monitoring thresholds proposed in the literature are mainly for spaces with fixed occupants. Determining CO2 threshold is challenging in spaces with changing occupancy due to the co-existence of quanta and CO2 remaining from previous occupants. Here, we propose a new calculation framework for deriving safe excess CO2 thresholds (above outdoor level), Ct, for various spaces with fixed/changing occupancy and analyze the uncertainty involved. We categorized common indoor spaces into three scenarios based on their occupancy conditions, e.g., fixed or varying infection ratios (infectors/occupants). We proved that the rebreathed fraction-based model can be applied directly for deriving Ct in the case of a fixed infection ratio (Scenario 1 and Scenario 2). In the case of varying infection ratios (Scenario 3), Ct derivation must follow the general calculation framework due to the existence of initial quanta/excess CO2. Otherwise, Ct can be significantly biased (e.g., 260 ppm) when the infection ratio varies greatly. Ct can vary significantly based on specific space factors such as occupant number, physical activity, and community prevalence, e.g., 7 ppm for gym and 890 ppm for lecture hall, indicating Ct must be determined on a case-by-case basis. An uncertainty of up to 6 orders of magnitude for Ct was found for all cases due to uncertainty in emissions of quanta and CO2, thus emphasizing the role of accurate emissions data in determining Ct.

Low Subcritical CO2 Adsorption-Desorption Behavior of Intact Bituminous Coal Cores Extracted from a Shallow Coal Seam.

This study focuses on improving fundamental understanding of low, subcritical CO2 adsorption-desorption behavior of bituminous coals with the aim to evaluate the utility of shallow-depth coal seams for safe and effective CO2 storage. Comprehensive data and a detailed description of coal-CO2 interactions, e.g., adsorption, desorption, and hysteresis behavior of intact bituminous coals at CO2 pressures <0.5 MPa, are limited. Manometric sorption experiments were performed on coal cores (50 mm dia. and 30- or 60-mm length) obtained from a 30 m deep coal seam located at the Upper Silesian Basin in Poland. Experimental results revealed that the adsorption capacities were correlated to void volume and equilibrium time under low-pressure injection (0.5 MPa). The positive deviation, observed in the hysteresis of adsorption-desorption isotherm patterns, and the increased sample mass at the end of the tests suggested CO2 pore diffusion and condensation. This behavior is vital for assessing low-pressure CO2 injection and storage capabilities of shallow coal seams where confining pressure is much lower than that of the deeper seams. Overall, CO2 adsorption depicts a type II adsorption isotherm and a type H3 hysteresis pattern of the IUPAC classification. Experimental results fitted better to the Brunauer-Emmett-Teller model than the Langmuir isotherm model. CO2 adsorption behavior of intact cores was also evaluated by characteristic curves. It was found that Curve I favored physical forces, i.e., the presence of van der Waals/London dispersion forces to describe the coal-CO2 interactions. However, analysis of Curve II indicated that the changing pressure-volume behavior of CO2 in the adsorbed phase, under low equilibrium pressures, cannot be ignored.

CO2 Reaction-Diffusion Experiments in Shales and Carbonates

The evaluation of caprock integrity and reservoir efficiency is critical for safe CO2 geological storage management. It is therefore important to investigate geochemical reactions between CO2-rich fluids and host rocks and their contribution in retaining CO2 at depth. This study deals with diffusive reaction experiments on shales and carbonate samples cored from an offshore structure in the Malaysian basin, a potential target for CO2-enhanced gas recovery. The aim is to evaluate the CO2 reaction front velocity in a typical shaly caprock and the mineral response of the reservoir. Rock samples were characterized in terms of texture, chemistry, and mineralogy by X-ray diffraction, electron microscopy (SEM), microanalysis (EDS), infrared spectroscopy (FT-IR), rock geochemistry (XRF), and mercury injection capillary permeability (MICP). Performed analyses show mineralogical alteration induced by CO2 as it penetrated into the samples. Carbonate dissolution and weathering of pyrite to form secondary carbonates belonging to siderite-ankerite series were observed along two reaction fronts. Estimated diffusion coefficients of CO2 are two orders of magnitude lower than CO2(aq) molecular diffusion in pure water and from half to an order of magnitude lower than diffusivity computed on unaltered sample, highlighting the important effect of gas–water–rock reactions on the CO2(aq) diffusivities in shales and carbonates. Results obtained in this study provide an insight regarding the effect of geochemical reactions on CO2 transport and represent a further discussion point on the diffusion coefficients.

Insights into the interaction of a shale with CO2

Abstract. Caprock formations, such as shales, play a key role in safe underground CO2 storage since they serve as a hydromechanical barrier that prevents migration of the injected CO2 to the surface. While their hydromechanical response is important to ensure their sealing capacity, interaction with the injected CO2 involves additional thermo–hydro–chemo–mechanical (THCM) phenomena that may threaten the long-term integrity of the caprock. The low-transport properties of shales make them a suitable caprock material, but at the same time challenging to study due to the very long timescales (months/years) that are required for the various THCM processes to manifest. In this work, the long-term multiphysical interaction of the Opalinus Clay shale with liquid and supercritical CO2 is studied in 3D with live X-ray tomography. Three-dimensional analysis reveals the localised response of the coupled THCM processes that is often indistinguishable with conventional lab testing protocols. To improve spatial and temporal resolution while applying field-representative pressure and temperature conditions, small-sized samples are studied. Long-term injection of liquid CO2 resulted in significant fissuring of calcite-rich zones that were for the first time visualised and quantified from the X-ray images. Additionally, a re-arrangement of the pre-existing micro-fissures in the clay matrix was observed. The volumetric response during direct exposure of an Opalinus Clay sample to supercritical CO2 revealed an initial swelling at pre-fissured zones and initiation of new micro-fissures at areas of direct contact with the anhydrous CO2 due to pore water evaporation. Advanced 3D image analysis showed an increasing CO2 uptake in the caprock material with time, suggesting potential CO2 trapping in the material.