The development of broadly applicable storage coefficients for determining CO2 storage resource/capacity estimates has been identified as a critical component for stakeholders to make informed decisions regarding the potential implementation of large-scale CO2 storage. While several evaluations have been conducted to determine CO2 storage resource/capacity estimates, they are the result of different methodologies, and a comparison of the results is often difficult and/or misleading. Thus the development of approaches and methods for developing CO2 storage estimates that can be applied to assessments at a wide range of scales has been identified as crucial to the advancement of broadly applicable and comparable "storage coefficients." At the heart of the matter is the fact that only a fraction of the pore space within any given geological formation will be available or amenable to CO2 storage. The purpose of a storage coefficient is to assign a value to that fraction of a given pore volume in which CO2 can be effectively stored. In order to develop broadly applicable storage coefficients, three methodologies for determining storage resource/capacity in deep saline formations were evaluated: two that can be applied to open systems and one for application in closed systems. In the end, effective storage coefficients were developed for application to deep saline formations at scales ranging from site-specific evaluations to entire formations. Real-world data sets and numerical modeling simulations were used to calculate storage coefficients at the site-specific scale for three lithologies, ten depositional environments, and five structural settings. These results can then be modified and translated into effective storage coefficients that can be applied at the formation scale for the three main lithologies. To develop estimates of effective storage resources for entire basins, estimates for each formation within the basin must be summed. This same methodology can be applied for estimating effective storage resources within state/provincial and national boundaries. In this way, the application of the broadly applicable effective storage coefficients developed by this project can be used to estimate the effective storage resource at levels ranging from site-specific to formation-level, ultimately spanning large sedimentary basins and even entire nations and continents. Introduction In recent years, the concept of mitigating global climate change through large-scale carbon capture and storage (CCS) into geologic media (saline formations, depleted hydrocarbon reservoirs, and unminable coal seams) has gained worldwide attention. Identifying potential geologic sinks for carbon dioxide (CO2) storage and developing reliable estimates of their storage resource/capacity is a critical component of determining the efficacy of CCS. While numerous evaluations have been conducted to develop storage resource/capacity estimates for geologic formations throughout the world, they are the product of several different methodologies, and comparison of the results of one evaluation to another is often difficult and misleading. The IEA Greenhouse Gas Research & Development (R&D) Programme (IEA-GHG) has been working closely with a wide variety of international organizations, including the U. S. Department of Energy (DOE) to develop approaches and methods for developing CO2 storage resource/capacity estimates that can be applied to assessments at the site-specific, local, regional, basin, and country scales. Recently, IEA-GHG and DOE have identified the development of technically robust storage coefficients as being crucial to the advancement of broadly applicable and comparable storage resource/capacity estimates at all scales.

The souring of oil (increasing concentrations of hydrogen sulfide [H 2 S] gas) from reservoirs in the Bakken Formation has been observed in the field. Souring of oil presents challenges including but not limited to health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements. As such, sour oil and gas have lower profit margin (~10% lower price) than traditional sweet Bakken crude.The understanding of causes for souring in the Bakken Formation and its timely identification are essential for determining the best operational practices and mitigation procedures at this formation. This paper will present an outline of the research goals, a current understanding of souring at the Bakken, and initial findings. Over the course of this project, the series of case-oriented uncoupled compositional reservoir simulations were developed to research the most probable mechanism of H 2 S generation in the Bakken Formation. The results of this investigation will be correlated in the future with field data from the Bakken oil field operator and laboratory experiments.

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Carbon dioxide (CO2) storage estimates are a critical component of the decision-making process when considering the implementation of large-scale CO2 storage in the subsurface. In order to compare storage resource/capacity estimates, both the scale of the estimate and the type of estimate must be considered. To date, the classification of resources and commodities has been used almost exclusively for valuable materials that can be economically extracted from the subsurface, e.g., hydrocarbons, metal ore, coal, etc. These industries have benefited from the establishment of classification systems with consistent terms and definitions that have gained international acceptance and allow for systematic accounting and comparison of resources across geological, geographical, and jurisdictional boundaries. As the carbon capture and storage (CCS) industry grows, there is increasing need for an accepted classification system that describes the available CO2 storage resource. While the classification systems used in the mining and hydrocarbon industries have elements that are instructive and sometimes indirectly applicable with respect to CO2, the direct application of those systems is largely insufficient. This is because, in the context of geological CO2 storage, the desired resource is not something to be removed from a subsurface reservoir but rather the accessible pore volume of the reservoir itself. Although much work has been accomplished, particularly by the Carbon Sequestration Leadership Forum (CSLF), and the U.S. Department of Energy (DOE) in the Carbon Sequestration Atlas of the United States and Canada, inconsistencies in definitions related to CCS exist between groups, and a widely accepted set of definitions for discussing CO2 storage resource and capacity has not yet been established. In order to move the CCS industry toward a useful set of definitions and provide a consistent set of terms, an improved classification system has been developed to not only address the level of the assessment but also the scale at which the assessment was made. Introduction Carbon capture and storage (CCS) represents an emerging set of technologies aimed at reducing the amount of anthropogenic carbon dioxide (CO2) that reaches the atmosphere by injecting and storing it in geological formations. Several targets have been identified as amenable to the injection and storage of CO2, most notably oil and gas reservoirs, saline formations, and unminable coal seams. Other potential targets have been proposed for future use, including basalts and organic shales; however, they are not considered for this paper. Within these target formations, a variety of trapping mechanisms must be considered, e.g., physical, solubility, and mineral. Each of the trapping mechanisms varies in its permanence and relevance over different timescales, with physical trapping beneath a low-permeability cap rock the most notable in the short term.

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