Geological Sequestration Research Articles

Numerical Simulation of Thermo‐Hydro‐Mechanical‐Chemical Response Caused by CO2 Injection into Saline Geological Formations: A Case Study from the Ordos Project, China

AbstractThermo‐hydro‐mechanical‐chemical (THMC) interactions are prevalent during CO2 geological sequestration (CGS). In this study, a sequential coupling THMC numerical simulation program was constructed, which can be used to explore the following issues of CGS: fluid and heat flow, solute transport; stresses, displacements and rock failures related to geo‐mechanical effects; equilibrium and kinetic chemical reactions; chemical damage to mechanical properties of the rock. Then, the coupling program was applied to the Ordos CGS Project to study the formation response under the multi‐field interaction caused by CO2 injection. The simulation results show that the mechanical process dominates the short CO2 injection period. Specifically, the formation's permeability near the injection well increases by 43%, due to the reduction of effective stress, which significantly promotes the lateral migration of CO2. When the injection rate exceeds 0.15 million tons per year, the cohesion of the reservoir rock is not enough to resist the shear force inside the rock and rock failure may occur. During the subsequent long‐term sequestration period (200 years), the influence of mineral reactions gradually increases. Due to calcite dissolution, the shear modulus of caprock is predicted to decrease by 7.6%, which will to some extent increase the risk of rock failure.

Influence of the grain shape and packing texture on the primary porosity of sandstone: Insights from a numerical simulation

Sandstone is an important carrier of underground hydrocarbon and the geological sequestration of carbon dioxide. Primary porosity is an important parameter used to predict reservoir quality, and it is influenced by the grain shape, grain‐size distribution and grain packing texture. However, few studies have focused on deriving multivariate equations of the grain size, grain‐size distribution and grain packing texture to predict the primary porosity of sandstone. The natural sedimentary process of sandstones was designed and simulated using a discrete element method. The results confirmed that the primary porosity is influenced by roundness, flatness, elongation, grain‐size distribution and grain packing texture; of the attributes, the mean grain size contributes less to the primary porosity of sandstone. Based on 193 simulated sandstone samples with a one‐component grain packing texture, a mathematical model considering roundness, flatness, elongation, grain packing texture and grain‐size distribution was proposed. The maximum, mean absolute and root mean square errors were 0.71, 0.26 and 0.32, respectively. The correlation coefficient between the simulated results and mathematical predicted results was 0.94. Furthermore, the primary porosity was positively correlated with the kurtosis of the grain‐size distribution in sandstone with the same grain shape but different kurtosis. The primary porosity was found to be independent of the mean grain size and mainly affected by the grain packing texture. Moreover, the primary porosity prediction model for sandstones with different grain‐size distribution curves based on the grain packing texture, which was proposed by the author in a previous study, was verified, and the correlation coefficient between the simulated results and predicted results was >0.92. The new mathematical model proposed in this study is a useful supplement for key parameter acquisition in the previous primary porosity prediction model of sandstone with different grain‐size distribution curves and grain packing texture. A mathematical model considering roundness, flatness, elongation, grain packing texture and grain‐size distribution is of great significance for reservoir quality prediction and conducting a quantitative evaluation of the diagenesis.

Simulation study on the evolution of cement plug sealing capability in CO2 geological sequestration wells

CO2 geological sequestration technology injects CO2 into the target geological formation through a borehole. Usually, cement plugs are used to seal the well after finishing the injection. Ensuring the plugs' sealing capability is the focus after CO2 sequestration, which is also directly related to the final result of the sequestration. Since the cement's mechanical and poroperm behavior under corrosion has yet to be fully considered, this paper developed a 3D finite element model of the plug-formation, which considers the changes of the corrosion zone. This paper simulates the micro-annulus propagation on the bonding surface, quantifies the effects of corrosion time and corrosion environment on the propagation characterivdstics, and discusses the effects of potential changes in bonding strength and corrosion zone Poisson's ratio after corrosion on the plugs' sealing. The simulation results show that: with the increase of corrosion time, the plug is more prone to radial deformation, the micro-annulus propagation pressure decreases as a power function, and the micro-annulus axial propagation distance is longer. Compared with the liquid-phase corrosion environment, the micro-annulus is more easily propagated in the gas-phase corrosion environment, the micro-annulus aperture is larger, and the propagation distance is longer. When the bond strength and corrosion zone Poisson's ratio decrease after corrosion, the plug's sealing capability will weaken further. In CO2 sequestration wells, following the general abandonment requirements is not appropriate. Improving the cement formulation to reduce the corrosion rate, enhancing the cement's strength after corrosion, and extending the plug length will help maintain the plug's long-term sealing. This study explains the effect of CO2 chemical attack on the plug's sealing. The results have important implications for controlling the long-term sealing capability of CO2 geological sequestration wells.

Wetting transition and fluid trapping in a microfluidic fracture

Immiscible fluid-fluid displacement in confined geometries is a fundamental process occurring in many natural phenomena and technological applications, from geological CO2 sequestration to microfluidics. Due to the interactions between the fluids and the solid walls, fluid invasion undergoes a wetting transition from complete displacement at low displacement rates to leaving a film of the defending fluid on the confining surfaces at high displacement rates. While most real surfaces are rough, fundamental questions remain about the type of fluid-fluid displacement that can emerge in a confined, rough geometry. Here, we study immiscible displacement in a microfluidic device with a precisely controlled structured surface as an analogue for a rough fracture. We analyze the influence of the degree of surface roughness on the wetting transition and the formation of thin films of the defending liquid. We show experimentally, and rationalize theoretically, that roughness affects both the stability and dewetting dynamics of thin films, leading to distinct late-time morphologies of the undisplaced (trapped) fluid. Finally, we discuss the implications of our observations for geologic and technological applications.

Composite confining systems: Rethinking geologic seals for permanent CO2 sequestration

Permanent containment is paramount for geologic carbon sequestration. Petroleum experience proves the possibility but also creates bias—to date, carbon storage projects have used seals similar to those of producing petroleum accumulations—thick, laterally extensive, effectively impermeable layers. These work for CO2, but may not be present where needed, nor optimal for sequestration. We introduce the concept of composite confining systems, defined here as multi-layer stratigraphic systems of discontinuous barriers with no a priori requirements for continuity or minimum capillary entry pressure. We explore the concept through physical analog modeling, geologic characterization and full-scale numerical modeling. We find that barriers need only offer enough capillary entry pressure contrast to divert the flow of CO2 and that barrier frequency and barrier area are the key variables in retarding vertical migration. Data from Southern Louisiana Miocene deltaic deposits shows ∼5–15 mudstone barriers/100 m of section, with average mudstone lengths of over 1 km and aspect ratios ∼2:1, giving effective ratios of vertical to horizontal permeability (kv/kh) of ∼0.0005. Full-scale reservoir models show that these systems can completely arrest vertical migration of industrial-scale volumes of CO2 (10's of megatons) within a few 10's of meters of stratigraphic section. Unlike more conventional petroleum seals and traps, which retain CO2 in a concentrated, mobile state, composite confining systems disperse and immobilize it via migration-assisted trapping. The greatest risks to performance of composite confining systems are the same as for conventional seals–the potential shortcuts across stratigraphic barriers, e.g., legacy wells, fluid escape pipes and permeable faults that focus flow.

Effects of CO 2 phase state on the seismological properties of porous materials: implications for seismic monitoring of volcanic hazards and sequestered carbon

Abstract Time-lapse seismic monitoring is a key component in the geological sequestration of greenhouse gases. Currently, a lack of understanding of the influence of injected CO 2 on rocks’ geophysical signatures is reported. Using a novel ultrasonic experimental system, we measured the variations in the longitudinal (P) and transverse (S) elastic wave speeds of a CO 2 -saturated porous medium at different pressure and temperature conditions around the CO 2 critical point. The results show that both P- and S-wave speeds, corrected to seismic frequencies, decreased by more than 4.5% across the CO 2 gas to liquid and gas to supercritical states, primarily as a consequence of CO 2 density increase. This study provides a-20 firm basis for the use of seismological methods in monitoring sequestered CO 2 ; although the abruptness, and hence remote seismic detectability, depends on which phase boundary is crossed. Further, these measurements also allow us to compare observations to frequency-dependent wave propagation theory. The observed wave speeds mostly align with those calculated at 1 MHz using the Biot theory for both CO 2 and H 2 O saturated states. However, the observed and calculated wave speeds diverge above the phase transition in some of the tests, possibly due to the kinetics of the phase transition within a porous medium. As such, aside from the direct utility in providing information on the expected seismic responses, the CO 2 provides a highly tunable fluid that can be advantageous for experimental studies.

Mapping existing wellbore locations to compare technical risks between onshore and offshore CCS activities in Texas

AbstractCarbon dioxide capture and geologic storage (CCS; geologic sequestration) is a promising technology for reducing anthropogenic greenhouse gas emissions to the atmosphere from industrial point sources. Aspects of CCS have been investigated for over two decades, and many large‐ and small‐scale geologic storage field demonstration projects are now underway globally. Interest in offshore CCS has been increasing in recent years (e.g., European Union, Australia, Japan, and the United States). Deep geologic storage in offshore settings is analogous to onshore CCS activities in many respects (i.e., geologic and geotechnical aspects), but is distinct from previously explored seabed sediment CO2 storage) or deep marine dissolution). Given the large subsurface geologic storage volumes available in offshore settings, much discussion of offshore CCS is focused on the benefits and risks of such activity compared to onshore settings. Similar to onshore settings, existing (legacy) wells likely present the most direct migration pathway and largest risk of noncontainment in offshore settings. As part of current studies to evaluate geologic storage options in offshore settings along the Texas coast and greater Gulf of Mexico (GoM), mapping of the geographic distribution and ages of wells in a region containing coastal counties and extending 30 miles offshore Texas indicates that both well spatial density and well age decrease moving from onshore to offshore. Results suggest reduced risk of leakage owing to more rigorous and documented well completion and abandonment practices for these generally younger wells (although many are decades old). A result of decreased well density is that larger areas are available for leasing for CCS projects that avoid legacy wells altogether (> 1 mile from any existing well). The one‐mile designation is used as an arbitrary convention, and while it is recognized that this is smaller than a typical area of review (AoR) for permitting, each site will have a different AoR radius for consideration. The combination of large subsurface storage volumes under control of a single landowner and reduced risks from legacy wells makes offshore CCS attractive in the GoM. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Combined machine-learning and optimization models for predicting carbon dioxide trapping indexes in deep geological formations

Emissions of carbon dioxide (CO2) are a major source of atmospheric pollution contributing to global warming. Carbon geological sequestration (CGS) in saline aquifers offers a feasible solution to reduce the atmospheric buildup of CO2. The direct determination of the trapping efficiency of CO2 in potential storage formations requires extensive, time-consuming simulations. Machine-learning (ML) models offer a complementary means of determining trapping indexes, thereby reducing the number of simulations required. However, ML models have to date found it difficult to accurately predict two specific reservoir CO2 indexes: residual-trapping index (RTI) and solubility-trapping index (STI). Hybridizing ML models with optimizers (HML) demonstrate better RTI and STI prediction performance by selecting the ML model’s hyperparameters more precisely. This study develops and evaluates six HML models, combining a least-squares-support-vector machine (LSSVM) and a radial-basis-function neural network (RBFNN) with three effective optimizer algorithms: genetic (GA), cuckoo optimization (COA), and particle-swarm optimization (PSO). 6810 geological-formation simulation records for RTI and STI were compiled from published studies and evaluated with the six HML models. Error and score analysis reveal that the HML models outperform standalone ML models in predicting RTI and STI for this dataset, with the LSSVM-COA model achieving the lowest root mean squared errors of 0.00421 and 0.00067 for RTI and STI, respectively. Sensitivity analysis identifies residual gas saturation and permeability as the most influential input variables on STI and RTI predictions. The high RTI and STI prediction accuracy achieved by the HML models offers to reduce the uncertainties associated with CGS projects substantially.

Numerical study on the influence of temperature on CO2-ECBM

CO2-ECBM can not only improve the production of CBM, but also contribute to CO2 geological sequestration, which has multiple economic effects. In this paper, COMSOL simulation software was used to conduct numerical simulation studies on the 3# coal seams in Qinshui Basin. A fully coupled model of coal deformation, gas flow and migration, and thermal transfer was established to evaluate the effect of temperature on the production of CBM by CO2 injection. The results indicates that temperature is a key factor affecting CH4 production and CO2 storage. Increasing injection temperature can significantly accelerate the process of gas displacement and the CO2 storage is more sensitive to temperature than the CH4 production. In contrast, both the CH4 production and the CO2 storage decrease with the increase of initial temperature of coal seam and the permeability will decrease faster. With the increase of injection time, the effective influence radius of displacement increases, but the increment of influence radius decreases gradually. The lower the initial temperature of the coal seam, the larger the influence radius, the influence radius increases as a whole with the increase of time. Low Young's modulus or high Poisson's ratio can effectively increase CO2 storage and CH4 production.

Design, construction, and validation of an in-situ groundwater trace element analyzer with applications in carbon storage

It is estimated that carbon emissions should reach net-zero by 2050 to meet important climate targets. Carbon capture is likely necessary to reach these targets, requiring a long-term storage solution such as geological carbon sequestration. However, as with any subsurface activity, leakage can occur, potentially impacting groundwater quality near the storage site. Rapid detection is essential to mitigate damage to this resource. Since CO2 will acidify groundwater, the concentrations of acid soluble minerals and associated cations will increase. Thus, an in-situ, real-time element analysis system based on laser-induced breakdown spectroscopy (LIBS) is under development to monitor these elements. The system splits the traditional LIBS system into a miniature, all-optical sensor head built around a passively Q-switch laser fiber coupled to a control unit. Previous work has validated the LIBS technique for use at high pressure as well as the split system design. In this work, a fieldable prototype sensor is developed and tested in an onsite monitoring well where trace elements concentrations (approx. 0–3 ppm) were tracked over 20 days. These concentrations varied in response to local rainfall, diluting with increased rain, demonstrating the ability of a LIBS-based sensor to track trace elements under real-world conditions.

A State-of-the-Art Review on Technology for Carbon Utilization and Storage

Carbon capture utilization and storage (CCUS) technologies are regarded as an economically feasible way to minimize greenhouse gas emissions. In this paper, various aspects of CCUS are reviewed and discussed, including the use of geological sequestration, ocean sequestration and various mineral carbon mineralization with its accelerated carbonization methods. By chemically reacting CO2 with calcium or magnesium-containing minerals, mineral carbonation technology creates stable carbonate compounds that do not require ongoing liability or monitoring. In addition, using industrial waste residues as a source of carbonate minerals appears as an option because they are less expensive and easily accessible close to CO2 emitters and have higher reactivity than natural minerals. Among those geological formations for CO2 storage, carbon microbubbles sequestration provides the economic leak-free option of carbon capture and storage. This paper first presents the advantages and disadvantages of various ways of storing carbon dioxide; then, it proposes a new method of injecting carbon dioxide and industrial waste into underground cavities.

Enabling site-specific well leakage risk estimation during geologic carbon sequestration using a modular deep-learning-based wellbore leakage model

Amid growing climate concerns, geologic carbon sequestration (GCS) is a promising technology for mitigating net carbon emissions by storing CO2 in reservoirs. Oil and gas brownfields are an attractive option for CO2 storage, but these sites have many historical wellbores from petroleum production that can provide potential leakage pathways for CO2 or formation brine. Therefore, risk management of GCS operations requires an assessment of potential well leakage. Due to the high uncertainty of subsurface systems, stochastic approaches are ideal for quantifying the range of risk behaviors, but they must be computationally efficient in the face of complex physics. Here, we develop a new deep learning wellbore model to predict the leakage of CO2 and brine through wellbores. Full physics numerical simulations were used to generate data sets. A complex regression problem was divided into sub-problems of classification and regression to improve model performance. Feature analysis quantifies the impact of each feature on model prediction and enables us to select only effective features for model training. The model shows high predictive performance across a wide range of geologic and injection conditions and well attributes. A case study illustrates how the model is applied to assess well leakage in GCS operations.

Influence Factors and Feasibility Evaluation on Geological Sequestration of CO2 in Coal Seams: A Review.

The geological sequestration of CO2 in coal seams holds significant implications for coalbed methane development and greenhouse gas mitigation. This paper examines the principles, influencing factors, and evaluation methods for geological CO2 sequestration in coal seams by analyzing relevant domestic and international findings. Suitable geological conditions for CO2 sequestration include burial depths between 300 and 1300 m, permeability greater than 0.01 × 10-3 μm2, caprock and floor strata with water isolation capabilities, and high-rank bituminous coal or anthracite with low ash yield. Geological structures, shallow freshwater layers, and complex hydrological conditions should be avoided. Additionally, the engineering conditions of temperature, pressure, and storage time for CO2 sequestration should be given special attention. The feasibility evaluation of CO2 geological storage in coal seams necessitates a comprehensive understanding of coalfield geological factors. By integrating the evaluation principles of site selection feasibility, injection controllability, sequestration security, and development economy, various mathematical models and "one vote veto" power can optimize the sequestration area and provide recommendations for rational CO2 geological storage layout.

A novel method to estimate the Stress-Dependent Kozeny-Carman constant of Low-Permeability, clastic sedimentary rocks

The stress-dependent permeability of low-permeability sedimentary rocks has seized attention because of the growing need for fossil fuels, geological carbon sequestration, and radioactive waste disposal. The Kozeny-Carman equation (K-C equation) is a well-known model for predicting the permeability of sedimentary rocks. The Kozeny-Carman constant (K-C constant, ckc) in the K-C equation accounts for the shape of the pores and the complexity of the pore conduit geometry in rocks. The pore structure of rocks varies owing to compaction at different burial depths. Therefore, the ckc is stress-dependent, a key parameter for understanding the stress-dependent permeability of rocks. However, measuring the stress-dependent ckc in low-permeability rocks is challenging. The present study proposes a novel approach for measuring the stress-dependent ckc of low-permeability rocks. The key elements of the proposed approach are (1) utilizing the Klinkenberg slip factor to evaluate the pore structure of rocks under stress, and (2) measuring rock porosity and permeability simultaneously under stress. This study amended the existing apparatus to fulfill the aforementioned purpose. Silty sandstone and clayey siltstone were selected to illustrate the novel ckc measurement method. The measured ckc values were compatible with the measurement results of documented sandstones and mudstones (most stress-independent). Interestingly, the ckc increased with increasing effective confining stress but started to decrease when the applied stress exceeded a certain critical value. Finally, we provide a synthetic case demonstrating the importance of considering stress-dependent ckc for permeability prediction under stress. If we neglect the stress dependence of ckc, the prediction of permeability using the K-C equation can induce errors up to several orders of magnitude.

Assessment of steel corrosion during geological carbon sequestration

W artykule przedstawiono tematykę związaną z korozją stali podczas geologicznej sekwestracji dwutlenku węgla. Ma to związek z tworzeniem się środowiska korozyjnego w obecności wody w środowisku CO2. Następuje wówczas pogorszenie się właściwości stali w wyniku jej reakcji z otaczającym środowiskiem i przechodzeniem wolnego metalu w związki, co wpływa w znacznym stopniu na bezpieczeństwo pracy urządzeń oraz stan rur stalowych. Opracowaną procedurę symulacji zjawiska korozji, metodykę badań, analiz i oceny korozji zweryfikowano testami laboratoryjnymi. Do testów zastosowano próbki stali L-80 (13Cr) wycięte z rury eksploatacyjnej. Natomiast środowisko korozyjne stanowił wilgotny czysty dwutlenek węgla o zawartości wody destylowanej wynoszącej 5000 ppm. Testy korozji przeprowadzono dla dwóch temperatur (40°C i 80°C) i dwóch ciśnień (8 MPa i 20 MPa), umożliwiających uzyskanie CO2 w fazie nadkrytycznej. Na podstawie wykonanych fotografii powierzchni stali nie stwierdzono widocznej korozji. Po testach korozji powierzchnie kuponów miały nadal charakter metaliczny, błyszczący. Wyznaczone na podstawie ubytku masy wartości szybkości korozji także nie wykazały procesu korozji stali w środowisku zawilgoconego CO2 dla zadanych warunków T i P. Dodatkowo wykonane obrazowanie i analiza powierzchni stali pod mikroskopem optycznym pozwoliły na zaobserwowanie początku tworzenia się korozji ogólnej (równomiernej) i wżerowej (miejscowej). Określono wielkości charakteryzujące wżery (średnią i maksymalną głębokość). Głębokość powstałych wżerów była rzędu od 0,00569 mm do 0,017 mm. Największą głębokość uzyskano w teście 4 (T = 80°C i P = 20 MPa). Na tej podstawie wyznaczono wartości szybkości korozji oraz wykonano dodatkową teoretyczną analizę głębokości korozji po 1 roku, 10, 50 i 100 latach. Pozwoliła ona stwierdzić, że niebezpieczna głębokość wżerów dla stali L-80 (13Cr) pojawi się po okresie 10 lat.

Optimal displacement of immiscible two-phase fluids in a pore doublet

Multiphase fluid flow in a pore doublet is a fundamental problem and is important for understanding the transport mechanisms of multiphase flows in porous media. During the displacement of immiscible two-phase fluids in a pore doublet, the transport process is influenced not only by the capillary and viscous forces, but also the channel geometry. In this paper, a mathematical model is presented of the two-phase fluid displacement in a pore doublet considering the effects of capillary force, viscous force, and the geometric structure. This leads to a new and more general analytical solution for the pore doublet system, and it is found that the displacement process is dominated by the capillary number, viscosity, and radius ratios. Also, the optimal displacement is defined, which refers to the wetting fluids in the two daughter channels breaking through the branches simultaneously (i.e., both having the same breakthrough time). Also, the critical capillary number corresponding to the optimal displacement is obtained, which is related to the radius ratio of the two daughter channels and the viscosity ratio of the two immiscible fluids. Finally, analytical results are presented for the displacement in the pore doublet, which can be used to explain and understand the preferential flows in porous media, such as for improving oil recovery from porous media; these are usually observed in oil recovery, groundwater pollution, and the geological sequestration of carbon dioxide.

Physical and chemical effects of H2O on mineral carbonation reactions in supercritical CO2

Mineral carbonation through reaction with supercritical CO2 (scCO2) is the ultimate pathway to permanent carbon storage for geological sequestration. Whether and how much H2O is required for the scCO2-mineral interaction to proceed readily, and the role of H2O in the reaction have been actively researched topics. We designed and built a novel in situ Raman reactor to study the carbonation product during brucite [Mg(OH)2]-scCO2 interaction, and investigated the role of free H2O by comparing the products in neat, H2O, and formamide (FM) conditions. We introduced FM to provide a physical polarity environment similar to that of H2O but without the chemical protonation effect. We further evaluated the role of structural H2O by conducting experiments with periclase (MgO). The in situ Raman analysis revealed the occurrence of brucite carbonation both in the presence of H2O and FM, demonstrating the effect of polarity in the reaction; in contrast, carbonation of periclase only occurred in H2O-saturated scCO2. The lack of carbonation of periclase with the presence of FM was attributed to the difficulty of magnesite mineralization, as CaCO3 was able to form in the CaO-FM-scCO2 system. Post-experimental X-ray diffractometry and Fourier-transform infrared spectrometry of the products showed that brucite carbonation yielded nesquehonite and hydromagnesite in H2O and FM, respectively; whereas periclase-scCO2 interaction in H2O produced a mixture of the two products. Rate calculations suggested that the carbonation reaction was much faster in H2O; nonetheless, 40–50% carbonation was still achieved in the Mg(OH)2-FM-scCO2 system after 330 h. Overall, our results showed that the brucite-scCO2 reaction could proceed without H2O under certain conditions – the polarity effect of H2O/FM was large enough to break the Mg–OH and MgO–H bonds and promote the carbonation process.

Scaling CO2–brine mixing in permeable media via analogue models

Supercritical ${\rm CO}_2$ injection and dissolution into deep brine aquifers allow its sequestration within geological formations. After injection, ${\rm CO}_{2}$ gas phase is buoyancy-driven over the denser aqueous brine, reaching an apparent gravitational stable distribution. However, ${\rm CO}_2$ dissolution in brine propels convection since the mixture is even denser than the underlying brine. This process still needs to be characterised comprehensively. Here, we investigate the irreversible mixing of dissolved ${\rm CO}_2$ in brine through laboratory-scale numerical experiments utilising the Hele-Shaw model (Letelier et al., J. Fluid Mech., vol. 864, 2019, pp. 746–767) and a fully miscible two-fluid system. In this scenario, mixing the less dense fluid – mimicking ${\rm CO}_{2}$ gas phase – with the heavier fluid – representing aqueous brine – catalyses cabbeling-powered convection. Our numerical simulations recover the laboratory results in porous media by Neufeld et al. (Geophys. Res. Lett., vol. 37, issue 22, 2010, L22404) and may explain the scaling law obtained by Backhaus et al. (Phys. Rev. Lett., vol. 106, issue 10, 2011, 104501) in Hele-Shaw cells. More remarkably, we show that the mass flux between the two analogue fluids, characterised by the Sherwood number $ {{Sh}}$ , obeys the universal scaling law $ {{Sh}}\sim {{Ra}}\, \vartheta _{scalar}$ , with $ {{Ra}}$ the Rayleigh number and $\vartheta _{scalar}$ the mean scalar dissipation rate. This paper sheds light on the fluid dynamics and solubility trapping in geological carbon sequestration.

Assessing the viability of CO[formula omitted] storage in offshore formations of the Gulf of Mexico at a scale relevant for climate-change mitigation

We investigate the feasibility of industrial-scale geological carbon sequestration as an effective climate change mitigation technology. We do so by performing numerical simulations of coupled multiphase flow and geomechanics on a representative field-scale geological model in the Gulf of Mexico that could become a typical CO2 storage site. We use our representative model to investigate two potential hazards associated with large-scale CO2 storage: (1) The potential that CO2 might migrate to shallower formations and (2) The potential that CO2 injection might induce seismicity due to destabilization of pre-existing faults. At our study location, we find that extensive distribution of clay minerals in fault zones in combination with large fault throws result in widespread occurrence of low-permeability faults that prevent migration of CO2 outside of the injection interval. Low-permeability faults act as flow barriers and can result in reservoir compartmentalization and pore pressure build-up. For our field-scale geological model, we find that the risk of induced seismicity is controlled by the choice of the injection location with respect to pre-existing low-permeability faults. Our model results indicate that industrial-scale CO2 storage in the Gulf of Mexico is feasible, but that a priori reservoir characterization and the choice of injection location are crucial to mitigate the potential occurrence of induced seismicity and CO2 migration to shallower formations.

Review on Experimental Investigation into Formation Damage during Geologic Carbon Sequestration: Advances and Outlook

Review on Experimental Investigation into Formation Damage during Geologic Carbon Sequestration: Advances and Outlook