Analysis of synthetic data was performed to determine the most cost-effective tomographic monitoring system for a geologic carbon sequestration injection site. Artificial velocity models were created that accounted for the expected velocity decrease due to the existence of a CO₂ plume after underground injection into a depleted petroleum reservoir. Seismic events were created to represent induced seismicity from injection, and five different geophone arrays were created to monitor this artificial seismicity. Double-difference tomographic inversion was performed on 125 synthetic data sets: five stages of CO₂ plume growth, five seismic event regions, and five geophone arrays. Each resulting velocity model from tomoDD—the double-difference tomography program used for inversion—was compared quantitatively to its respective synthetic velocity model to determine an accuracy value. The quantitative results were examined in an attempt to determine a relationship between cost and accuracy in monitoring, verification, and accounting applications using double-difference tomography. While all scenarios resulted in little error, no such relationship could be found. The lack of a relationship between cost and error is most likely due to error inherent to the travel time calculation algorithm used. / Master of Science

Recent studies suggest that continental flood basalts may be suitable for geologic carbon sequestration due to fluid-rock reactions that mineralize injected CO₂ on relatively short time-scales. Flood basalts also possess a permeability structure favorable for injection, with alternating high-permeability (flow margin) and low-permeability (flow interior) layers. However, little information exists on the behavior of CO₂ as it leaks through fractures characteristic of the flow interior, particularly at conditions near the critical point for CO₂. In this study, a two-dimensional 5 × 5 m model of a fracture network is built based on high-resolution LiDAR scans of a Columbia River Basalt flow interior taken near Starbuck, WA. Three-phase CO₂ flow is simulated using TOUGH3 (beta) with equation of state ECO2M for 10 years simulation time. Initial conditions comprise a hydrostatic pressure profile corresponding to 750-755 m below ground surface and a constant temperature of 32° C. Under these conditions, the critical point for CO₂ occurs 1.5 meters above the bottom of the domain. Matrix permeability is assumed to be constant, based on literature values for the Columbia River Basalt. Fracture permeability is assigned based on a lognormal distribution of random values with mean and standard deviation based on measured fracture aperture values and in situ permeability values from literature. In order to account for fracture permeability uncertainty, CO₂ leakage is simulated in 50 equally probable realizations of the same fracture network with spatially random permeability constrained by the lognormal permeability distribution. Results suggest that fracture permeability uncertainty has some effect on the distribution of CO₂ within the fractures, but network geometry is the primary control in determining flow paths. Fracture permeability uncertainty has a larger influence on fluid pressure, and can affect the location of the critical point within ~1.5 m. Uncertainty in fluid pressure was found to be highest along major flow paths below channel constrictions, indicating permeability at a few key points can have a large influence on fluid pressure distribution. / Master of Science / Geologic carbon sequestration (GCS) is a means of reducing greenhouse gas emissions using currently available technology. It consists of trapping carbon dioxide (CO<i>2</i>) released by the burning of fossil fuels at a large emitter, such as a coal fired power plant, and injecting it deep beneath the earth’s surface for permanent storage. This research builds on an increasing body of evidence that suggests that the Columbia River Basalt Group (GRBG), a large lava formation located in the northwestern United States, may be a suitable target for GCS. This is largely because CO<i>2</i> reacts with basalt rocks within a few years of injection to form stable minerals, after which it is permanently immobilized. This basalt province also contains alternating layers of rock, some of which have high permeability, meaning that they can accept CO<i>2</i> injections, and some of which have low permeability, meaning that they would block CO<i>2</i> rising from the injection layers. Layers with low permeability are called confining layers, and in the CRBG, they contain fractures that formed when the lava initially cooled. While some information about these fractures is known, it is impossible to know how easily fluid might flow through them at any given point (permeability) at the depths of interest for GCS. This study seeks to quantify the effects of that uncertainty, by building a model of CO<i>2</i> flow through a CRBG fracture set, and running that same model 50 times with all variables held constant, except the exact location of permeability values within the fracture network. Chemical reactions are not considered, so this model represents behavior in the network very soon after CO<i>2</i> is injected, before minerals start to form. The results of this model suggest that uncertainty in permeability values within fractures influences predictions of fluid pressure within the confining layer. This is important, because fluid pressure has a large influence on whether or not CO<i>2</i> will leak through the confining layer. This research will be useful in informing the model design of future researchers attempting to simulate GCS efforts in the CRBG and similar geologic formations.

With rising concentrations of CO₂ in the Earth's atmosphere causing concern about climate change, many solutions are being presented to decrease emissions. One of the proposed solutions is to sequester excess CO₂ in geological formations such as basalt. The deep subsurface is known to harbor much of the microbial biomass on earth and questions abound as to how this deep life is going to respond to the injection of CO₂. Many studies have used model microorganisms to demonstrate the ability of microbes to aid in the safe, permanent sequestration of CO₂ in the subsurface. The objective of this research is to characterize the microbial community present in the basalts at the Wallula pilot carbon sequestration well prior to the injection of CO₂ and then perform laboratory studies to determine how the native microbial community will respond to carbon sequestration conditions. Six samples were collected from the Wallula pilot well prior to the injection of CO₂ into the system. The microorganisms in these samples were characterized by pyrosequencing of 16S rRNA genes, revealing a community dominated by the Proteobacteria, Firmicutes, and Actinobacteria. The organisms detected were related to microbes known to metabolize hydrogen, sulfur, and single carbon compounds. These microorganisms may be stimulated in formations located at the fringe of the pool of injected CO₂. Laboratory studies revealed that the native microbial community suffered a two order of magnitude loss of population upon exposure to CO₂ under carbon sequestration conditions. The community also shifted from being dominated by Proteobacteria prior to CO₂ exposure to being dominated by Firmicutes after exposure. Specifically, the genus Alkaliphilus, which was previously undetected, appeared after CO₂ exposure and became dominant. The dominance of Alkaliphilus, along with other rare organisms which did not compose a majority of the population prior to the introduction of CO₂ to the system, indicates that members of the rare biosphere may be better adapted to changing environmental conditions specific to CO₂ sequestration than other indigenous cells. Thus, the rare biosphere should be examined closely as part of any environmental study, as these minority microorganisms may be the first indication of perturbation or impact. / Graduation date: 2013

Location is a critical component of business decisions. A firm's location decision may be influenced not only by market forces, such as the location of input suppliers, output processors and competitors, but also by government policies if such policies impact their expected profits and are applied non-uniformly across space. Likewise, a firm may adjust its business strategy, including opening and closing establishments and laying off employees as responses to changes in environmental regulations. In certain polluting industries, location decisions may include choosing potential storage sites for geologic carbon sequestration or finding landfills for industrial solid waste. There is extensive literature discussing the effects of environmental regulations or agglomeration economies on firm location decisions but few studies analyze the interactive effect of environmental regulations and agglomeration economies across regions in the United States. The potential consequences of changes in environmental regulations may include loss of polluting establishments, jobs, and income. Geological carbon sequestration offers long term storage opportunities to mitigate greenhouse gases (GHGs). Incorporating environmental risk into economic assessments of geological sequestration choices is crucial for finding optimal strategies in using alternative carbon storage sites with limited capacity. This dissertation consists of three essays that address the above issues. The first essay examines the interactive effects of air quality regulation and agglomeration economies on polluting firms' location decisions in the United States. Newly available annual (1989-2006) county-level manufacturing plant location data for the United States on seven pollution intensive manufacturing industries are applied in the analysis. Conditional Poisson and negative binomial models are estimated, an efficient GMM estimator is also employed to control for endogenous regulatory and agglomeration variables. Results indicate that births of pollution intensive manufacturers are deterred by stricter environmental regulation; and are attracted by local agglomeration economies. County attainment/nonattainment designations can impose heterogeneous impacts over space and across industries. The magnitude of the regulatory effect depends on the level of local agglomeration. Urbanization economies offset the negative impacts of environmental regulation, whereas localization economies can reinforce or offset the negative impacts of environmental regulation, depending on the industry. The second essay analyzes the effect of changes in regulatory environmental standards on the total stocks of establishments and local jobs and income Results indicate the effects vary across counties in the United States. When the standards were raised to 80 percent of the current level, from 2007 to 2009, the affected counties would lose a total of 326 establishments, 14,711 jobs with $705 million U.S. dollars of income each year. At the national economy level, the impacts of tightening environmental regulations are relatively small. The third essay constructs a dynamic optimization framework that deals with optimal utilization of alternative nonrenewable resource sites (geological formations) with possible negative externalities. We apply the model to an optimal usage problem of alternative long term CO₂ geologic storage sites for carbon. The storage sites are different in terms of capacity and potential leakage after CO₂ injection; the problem is determining the minimum cost for storing a fixed amount of CO₂ (sequestered) within a certain time period. Analytical solutions show the decision rule depends on the discount rate, storage capacities, marginal CO₂ storage costs, and environmental damage costs associated with CO₂ leakage from alternative sinks. The framework provides critical information about the optimal timing of switching from one resource sequestration site to another. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Feb. 1, 2013 - Feb. 1, 2015