Carbon capture and storage (CCS) has been identified as an urgent, strategic and essential approach to reduce anthropogenic CO2 emissions, and mitigate the severe consequences of climate change. CO2 storage is the last step in the CCS chain and can be implemented mainly through oceanic and underground geological sequestration, and mineral carbonation. This review paper aims to provide state-of-the-art developments in CO2 storage. The review initially discussed the potential options for CO2 storage by highlighting the present status, current challenges and uncertainties associated with further deployment of established approaches (such as storage in saline aquifers and depleted oil and gas reservoirs) and feasibility demonstration of relatively newer storage concepts (such as hydrate storage and CO2-based enhanced geothermal systems). The second part of the review outlined the critical criteria that are necessary for storage site selection, including geological, geothermal, geohazards, hydrodynamic, basin maturity, and economic, societal and environmental factors. In the third section, the focus was on identification of CO2 behaviour within the reservoir during and after injection, namely injection-induced seismicity, potential leakage pathways, and long-term containment complexities associated with CO2-brine-rock interaction. In addition, a detailed review on storage capacity estimation methods based on different geological media and trapping mechanisms was provided. Finally, an overview of major CO2 storage projects, including their overall outcomes, were outlined. This review indicates that although CO2 storage is a technically proven strategy, the discussed challenges need to be addressed in order to accelerate the deployment of the technology. In addition, beside the necessity of technoeconomic aspects, public acceptance of CO2 storage plays a central role in technology deployment, and the current ethical mechanisms need to be further improved.

The Bunter Sandstone formation in the UK Southern North Sea has been identified as having the potential to store large volumes of CO2. Prior to injection, CO2 is captured with certain amounts of impurities, usually less than 5%vol. The dissolution of these impurities in formation water can cause chemical reactions between CO2, brine, and rock, which can affect the reservoir quality by altering properties such as permeability. In this study, we explored the effect of CO2 and impurities (NO2, SO2, H2S) on reservoir permeability by measuring changes in grain size distributions after a prolonged period of 9 months, simulating in situ experimental conditions. It was found that the effects of pure CO2 and CO2-H2S are relatively small, i.e., CO2 increased permeability by 5.5% and CO2-H2S decreased it by 5.5%. Also, CO2-SO2 slightly decreased permeability by 6.25%, while CO2-NO2 showed the most pronounced effect, reducing permeability by 41.6%. The decrease in permeability showed a correlation with decreasing pH of the formation water and this equally correlates with a decrease in geometric mean of the grain diameter. The findings from this study are aimed to be used in future modelling studies on reservoir performance during injection and storage, which also should account for the shifts in boundaries in the CO2 phase diagram, altering the reservoir properties and affecting the cost of storage.

Carbon capture and storage (CCS) is a climate change mitigation method in which anthropogenic carbon dioxide (CO2) is captured from large point sources and stored in geological formations, in the ocean, or through mineral carbonation. CO2 can be injected and stored for a variety of reasons, including permanent disposal or enhanced oil recovery in certain oil fields. The main objective of this paper is to assess the advances made in CO2 storage projects globally. This study reviews the major companies/businesses that are involved in CCS deployment. The study also presents the alternative for the sequestration of CO2 into the geological formations through existing major projects. It explains their progress, structural and faulting configuration, CO2 transportation and injection, potential CO2 source(s), estimation of the storage capacity, etc. This study also highlights the monitoring programs that are used in different operating projects and the status of active projects. The study suggests that CCS faces further deployment challenges due to the heterogeneity and complexity of rock formations, high cost of deployment, possibility of formation damage during injection and potential for migration and leakage of CO2. Additionally, inappropriate strategy for CO2 injection may lead to wellbore integrity problems, formation of hydrates, and inadequate pressure control. More researchparticularly, geological evaluation before injection and storageis apparently needed.

Formation damage has the potential to impair and weaken reservoir productivity and injectivity, causing substantial economic losses. Oil and gas wells can be damaged by various mechanisms, such as solid invasion, rock–fluid incompatibilities, fluid–fluid incompatibilities, and phase trapping/blocking, which can reduce natural permeability of oil and gas near the wellbore zone. These can happen during most field operations, including drilling operations, completion, production, stimulation, and enhanced oil recovery (EOR). Numerous studies have been undertaken in recent years on the application of nanotechnology to aid the control of formation damage. This review has found that nanotechnology is more successful than traditional materials in controlling formation damages in different phases of oil and gas development. This is facilitated by their small size and high surface area/volume ratio, which increase reactivity and interactivity to the adjacent materials/surfaces. Furthermore, adding hydrophilic nanoparticles (0.05 wt %) to surfactants during EOR alters their wettability from 15 to 33%. Wettability alteration capabilities of nanoparticles are also exemplified by carbonate rock from oil-wet to water-wet after the concentration of 4 g/L silica nanoparticles is added. In addition, mixing nanoparticles to the drilling fluid reduced 70% of fluid loss. However, the mechanisms of impairment of conductivity in shale/tight formations are not consistent and can differ from one formation to another as a result of a high level of subsurface heterogeneity. Thus, the reactivity and interaction of nanoparticles in these shale/tight formations have not been clearly explained, and a recommendation is made for further investigations. We also recommend more nanotechnology field trials for future research because deductions from current studies are insufficient. This review provides more insights on the applications of nanoparticles in different stages of oil and gas development, increasing our understanding on the measures to control formation damage.

Nanomaterials have been used in the oil and gas industry to improve thermal stability, rheology properties, and reactivity through fluid dispersion into the formation. Nanomaterials in producing wells can control formation damage near the wellbore regions. Foreign fluid invasion to the reservoir rock during drilling, fracturing, completion, enhanced oil recovery, and workover causes an interaction with the rock formation and fluids. This results in formation damage such as clay swelling and deflocculation, solid particle invasion, and asphaltene precipitation, all of which reduce production and lead to significant economic losses. In this review, we present the application of nanomaterials to oilfields as a way of optimizing production with minimal formation damage near the wellbore regions. Also, this review presents how the laboratory experiments from nanomaterials were upscaled to oilfields. The different types of nanomaterials used to control formation damage across producing fields around the world were investigated. This study has shown that nanomaterials are more effective than traditional materials to be used in oilfields for controlling formation damage during various stages of oil and gas development and it recommends that the effect of the relationship between nanoparticle size and type should be explored for effective application. However, because formation damage is caused for a variety of reasons, this work points out that many types of nanomaterials need to be combined to achieve multipurpose mitigation. Furthermore, more research concerning the dispersion of nanoparticles in cement slurry and fracturing fluid should be undertaken.

Carbon capture and storage has been identified as an important and viable technology for climate change mitigation. The technology allows CO 2 generated from largescale sources, such as power plants and other heavy industries, to be captured and stored in deep geological formations. However, when CO 2 is stored in geological formations, there are possibilities of formation damage, which may reduce injectivity and storage capacity. In this study, formation damage during CO 2 injection and storage is reviewed through different experimental studies. The study has shown that the interaction between CO 2 , formation water, and rock minerals often results in mineral dissolution and precipitation, which affect reservoir permeability and porosity, which could possibly cause formation damage, compromising the reservoir storage capacity. This study also reveals that formation damage could be caused by the precipitation of sulfate scales, salt, and carbonate minerals. Additionally, in several studies, rock minerals were observed to dissolve and create free particles that were transported to occupy pore spaces along the fluid flow path, reducing permeability and impacting CO 2 injectivity and storage. It is worth noting that the reviewed experiments present short-term effects of formation damage on geological formations, while in reality, CO 2 storage is a long-term project, thus eliciting the need for more studies in that regard.

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