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Carbon dioxide has gradually found widespread usage in the field of science and engineering while various efforts have focused on ways to combat the menace resulting from the release of this compound in the atmosphere. A major approach to combating this release is by storage in various geological formations ranging from depleted reservoir types such as saline aquifers to other carbon sinks. In this research study, we reviewed the experimental, modeling, and field studies related to the underground storage of CO2. A considerable amount of research has been conducted in simulating and modeling CO2 sequestration in the subsurface. This review highlights some of the latest contributions. Additionally, the impact of CO2 sequestration on its surroundings due to chemical reactions, adsorption, capillarity, hysteresis, and wettability were reviewed. Some major challenges associated with CO2 injection have also been highlighted. Finally, this work presents a brief history of selected field scale projects such as Sleipner, Weyburn, In Salah, Otway Basin, Snøhvit, Alberta, Boundary Dam, Cranfield, and Ketzin. Thus, this study provides a guide of the CO2 storage process from the perspectives of experimental, modelling, and existing field studies.

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A review of the pressure transient analysis of flow in reservoirs having natural fractures, vugs and/or caves is presented to provide an insight into how much knowledge has been acquired about this phenomenon and to highlight the gaps still open for further research. A comparison-based approach is adopted which involved the review of works by several authors and identifying the limiting assumptions, model restrictions and applicability. Pressure transient analysis provides information to aid the identification of important features of reservoirs. It also provides an explanation to complex reservoir pressure-dependent variations which have led to improved understanding and optimization of the reservoir dynamics. Pressure transient analysis techniques, however, have limitations as not all its models find application in naturally fractured and vuggy reservoirs as the flow dynamics differ considerably. Pollard’s model presented in 1953 provided the foundation for existing pressure transient analysis in these types of reservoirs, and since then, several authors have modified this basic model and come up with more accurate models to characterize the dynamic pressure behavior in reservoirs with natural fractures, vugs and/or caves, with most having inherent limitations. This paper summarizes what has been done, what knowledge is considered established and the gaps left to be researched on.