International Journal of Greenhouse Gas Control最新文献

Previous work demonstrated Ca₂Fe₂O₅ (C₂F) can react in a blast furnace gas (BFG) with $P_{\text{CO}}/P_{C{O}_2}$ ratio of ∼1, despite of its reduction to CaO + Fe requiring a ratio of ∼3. This is possible due to the interaction with carbonation and the formation of other iron containing phases. Here, the proposed calcium and chemical looping combustion using C₂F was examined using process modelling in ASPEN Plus and MTDATA. The low chemical potential of oxygen in C₂F allows CO/H₂ combustion to be endothermic in the lower temperature carbonator (particularly when reducing to Fe_xO), leading to a more exothermic reaction during oxidation in the higher temperature calciner. In this scheme, the heat of BFG combustion is chemically pumped from the lower temperature carbonator to the higher temperature calciner using the looping material, reducing the energy use in the calciner by around 40 kW/mol-BFG compared to the calcium looping alone or to the calcium copper looping. The reincorporation of CaO and Fe/Fe_xO into C₂F would allow the calcination temperature to be lowered to 770 °C (compared with calcium looping, which requires ∼ 900 °C), and the system can be entirely autothermal.

Many studies on CO₂ injection monitoring focus on fault stability risks due to increased pore pressure. However, the temperature of the injected fluid can also significantly impact the near-wellbore region through cooling-induced strain, stress changes, and fracturing, necessitating tailored monitoring strategies. This study evaluates the potential for near-well monitoring by examining the magnitude of strain and associated failure scenarios in reservoir formations down to approximately 2.6 km, where injected CO₂ may cause temperature decreases of around 80 °C. The combined effects of pore pressure and cooling on stress path and elastic-inelastic strain are assessed using laboratory triaxial test data and selected well logs. The impact of cooling was simulated directly via uniaxial strain tests or indirectly through multistage tests with Acoustic Emission (AE) monitoring. An analytical approach based on the Mohr-Coulomb failure criterion is employed to evaluate the stress path relative to the failure criteria. Results indicate that shallow, uncemented sands and weakly cemented sandstones predominantly exhibit elastic expansion in response to injection. In contrast, deep, stiff sandstones can experience cooling-induced contraction, inelastic damage, and even fracturing. The findings are further discussed in relation to well-based monitoring techniques, including fibre optics and other methods.

Amine scrubbing processes for post-combustion CO₂ capture have been extensively studied and significantly improved via various novel designs. However, the amine scrubbers implemented nowadays were usually not optimized according to a number of different evaluation criteria. This is often due to the fact that, for high dimensional design spaces, the rigorous simulation runs needed to facilitate process optimization always calls for huge numbers of simulation software accesses and overwhelming iterative calculations. Therefore, in this study, the well-trained surrogate model was adopted to replace its rigorous counterpart for the purpose of ensuring efficient optimization runs in practical applications. In current study, two objectives, i.e., the specific equivalent work and the CO₂ capture level, were both rapidly and effectively optimized in various practical scenarios with different flue gas CO₂ concentrations. The corresponding operational parameters and utility consumptions were also easily obtained without additional effort. The computation results obtained so far showed that the proposed surrogate-assisted approach can be utilized to significantly reduce the computational load in practice.

Successful carbon injection operations depend critically on the management of risks, like induced seismicity. Here, we consider the bowtie risk management framework to organize pre-screening efforts around a prospective CO₂ injection operation near Trüllikon, Switzerland. First, potential barriers/threats are appraised via a literature review of the regional seismotectonics, hydrogeology, and nearby induced seismicity cases – which suggests a natural propensity for earthquakes because of the proximity to the Neuhausen Fault and a lack of effective underlying hydrogeological barriers. Next, we engineer barriers to fault reactivation by quantifying the fault slip potential. The closest (∼700 m) and most susceptible (∼3.0 km) portions of the Neuhausen Fault would require ∼1.7 MPa and ∼0.47 MPa for reactivation, respectively. The most susceptible (unknown) faults are normal slip (168° strike) that require ∼0.23 MPa for reactivation. Injection simulations indicate pressure changes on Neuhausen Fault segments of 0.01–0.05 MPa – values that are 1–2 orders-of-magnitude smaller than those needed for fault reactivation. These engineered barriers limit the potential for fault reactivation. However, if these barriers prove totally ineffective, we have also designed a traffic light protocol as a reactive mitigation measure. Forecast estimates of nuisance, damage, and fatalities are used to infer the last-possible stopping-point based on a comparison with operation-ending risks encountered at Basel and St. Gallen. This indicates a red- and yellow-lights of M_W ∼2.0 and M_W ∼0.0, respectively. We synthesize these disparate pre-screening analyses to recommend performance targets for real-time seismic monitoring. Future CO₂ operations will likely find our approach helpful for designing effective risk management.

CO₂ pipelines in CCUS frequently operate under unstable conditions due to transient factors, such as fluctuations in gas flow at the pipeline's starting and ending points. In this study, a one-dimensional transient flow model of CO₂ pipeline containing impurities is proposed, which is capable of coupling the hydraulic and thermal factors in the flow process to achieve the hydraulic calculation along the pipeline in the slow transient process. The engineering simulation software OLGA is used to test and verify the model, the result of which shows the model produces comparable calculation results with improved computational stability. The model is used to investigate the effects of the slow transient conditions and three capture methods on the pipeline, and the results show that: (1) the fluctuations in the outlet flow have different effects along the pipeline., (2) the existence of the gas distributing and gathering points has different effects on the upstream and downstream, (3) there is a big difference in the content and type of impurities under the different capture methods, which greatly affects the CO₂ pipeline operation under the slow transient conditions.

Geological carbon storage (GCS), particularly within deep saline aquifers, is considered a promising and efficient approach for sequestering significant volumes of anthropogenic CO₂. Computational models play a crucial role in assessing the feasibility of GCS, as they contribute to risk assessment, delineation of area of review, short-term and long-term monitoring design, regulatory compliance, decision-making, project planning and optimization. Currently, there are numerous applications for Class VI permits with accompanied GCS modeling results with various levels of implementation of best practices that the industry and academia has developed over the past several years. It is, therefore, necessary to document the established practices, with the aim of creating a more unified approach for modeling CO₂ behavior in aquifers. This study provides an overview of practices and workflows for reservoir modeling, particularly focusing on CO₂ storage in saline aquifers, with a specific attention to the United States regulations, including those set by the Environmental Protection Agency (EPA). We focus on technical challenges and potential solutions for creating reasonably accurate and scientifically robust GCS dynamic models within aquifers, while considering factors like hydrodynamics, geology, thermophysics, geochemistry, and geomechanics. Our goal is to provide a valuable resource to both industry stakeholders and academic researchers, enhancing the understanding of GCS dynamic modeling implementations and directing future research and development efforts in line with Class VI permit objectives.

The utilization of subsurface geologic media for carbon capture and storage through mineralization has been recognized as a reliable approach. However, less attention has been given to anhydrite rock type for CO₂ mineralization and storage. Anhydrite-rich rock formations, commonly found in various geological settings, have the potential to serve as natural carbon sinks through the mineralization of CO₂. Therefore, this study aims to investigate the mechanisms and potential of anhydrite-CO₂-brine interactions for carbon storage. The experimental approach involved exposing anhydrite-rich rock to supercritical CO₂-brine environments under varying conditions of fluid composition. Mineral transformation of an outcrop anhydrite-rich rock sample in static reactor under subsurface conditions of elevated temperature (60 °C) and pressure (104 bar), in the absence and the presence of SrCl₂ was conduct for a one-month period. Mineralogical and geochemical analyses, including, solution analyses, X-ray fluorescence, X-ray diffraction, micro-computed tomography, and mechanical properties were conducted to examine the changes in the composition and rock structure resulting from the interactions. The experimental reactions revealed that anhydrite undergoes mineral transformation upon exposure to supercritical CO₂-saturated brine to form stable minerals including calcite, dolomite, magnesite, and strontianite, which contributes to the potential for long-term storage of CO₂ in the subsurface geologic media. The efficiency and extent of carbon mineralization were found to be influenced by brine composition. These findings contribute to the understanding of the potential of these formations for carbon storage, opening avenues for further research and the development of effective carbon capture and storage strategies.

Fine-grained lithologies above CCS reservoirs cannot automatically be assumed to be mineralogically stable, or high quality top-seals to highly pressured CO₂ as saline aquifer have previously contained hydrostatically pressured water. We have investigated the mineralogy, pore systems and surface area characteristics of the Lower Cretaceous Rodby Shale, the caprock to the Captain Sandstone at the UK's planned Acorn/Goldeneye CCS site. Rodby Shale core was logged and analysed by XRD, light microscopy, and SEM. Grain size was measured using laser particle size analysis. Mercury intrusion porosimetry and nitrogen adsorption analysis were used to characterise the pore network. The Rodby is smectite-rich and contains abundant calcite as well as quartz silt with small quantities of chlorite and plagioclase. Calcite was sourced from benthic microfossils, locally recrystallised to create a pore-filling cement. The mean pore throat and pore body diameter are about 17 nm putting the Rodby in the mesopore range and suggesting a predominance of slit-like pores. There are three lithofacies in the Rodby Shale: (i) high surface area clay-rich shale, (ii) low surface area calcite-rich shale, (iii) intermediate surface area quartz-rich. if the second lithotype encountered CO₂, then the resulting calcite dissolution would lead to increasing surface area of the remaining shale. The Rodby Shale has good potential to be an effective barrier for CO₂ escape, based on assessments of diffusion rate and post-breakthrough advection rate as well as stability and sealing assessments.

This review describes the main geological and geomechanical aspects of CO₂-injection projects in the Brazilian Pre-Salt reservoirs, focusing on the storage potential and geomechanical aspects of CO₂ injection. The Pre-Salt reservoirs in the Santos Basin offer favorable conditions for CCS due to their geological characteristics and existing infrastructure. The thick evaporite caprock, primarily composed of halite, acts as an efficient seal against CO₂ migration. The ${\text{CO}}_2$-injection in the Pre-Salt has been active since 2010, with significant amounts of CO₂ already stored in the reservoirs. The volumetric assessment estimates the static storage capacity of the Pre-Salt reservoirs to be over 3.3 Gt of CO₂, considering only the four fields currently undergoing injection. Geomechanical constraints, including the maximum injection pressure and caprock integrity, are crucial considerations for safe CCS operations. The high stress regime and the hydrostatic state of the caprock minimize the risk of fracturing during injection. Furthermore, dynamic storage capacity calculations indicate the feasibility of injecting CO₂ into Pre-Salt reservoirs. This review provides insights into the current state and future prospects of CO₂-injection projects in the Brazilian Pre-Salt, contributing to the development of sustainable carbon mitigation strategies in the region.