Management Of Displaced Waters From Geological Carbon Dioxide Co2 Sequestration Within The Wyoming Rock Springs Uplift

The geological CO2 sequestration project at the Wyoming Rock Springs Uplift site is anticipated to result in the injection of 127.5 million tonnes (1.7 million tonnes per year) of CO2 per well into the Tensleep/Weber Sandstone and Madison Limestone formations over a 75 year period (Surdam et al., 2009). Large amounts of water must be extracted from the formations in order to maintain reservoir forces under fracture pressure limits. Sequestration of CO2 within the two aquifers would require approximately 75 million tonnes (1 million tonnes per year) of saline water to be removed from the reservoirs. An obvious challenge for this project is to determine how to manage the displaced water in order to prevent adverse environmental impacts. Therefore, the potential impacts of the displaced water on surface waters, soils, and vegetation ecosystems, where large amounts of displaced waters are utilized, were assessed in this study. Water treatment technologies were investigated to determine possible processes that might be implemented to reduce the salt content of the displaced water that would allow for other uses. Reverse osmosis (RO) and multi-stage flash (MSF) processes were considered the most promising desalination technologies, with RO more cost-efficient compared to MSF based on historical data. Consequently, it is imperative that possible scenarios be developed whereby the treated waters can be utilized for beneficial uses, which include: industrial--power plants or water treatment plants, oil and gas industry, and soda ash production; agricultural--irrigation and livestock; ecological--enhanced in-stream flow or fisheries, wetlands or artificial wetlands, injection for aquifer storage or recovery and recreation areas; domestic--drinking water, dust abasement, fire-fighting and vehicles wash; and others--mineral extraction.

Developing effective management strategies for greenhouse gases, such as carbon dioxide (CO2), is receiving growing interest as concerns over their role(s) in affecting global climate change develop. Geologic sequestration has been identified as one possible avenue for storing CO2, which would otherwise have been discharged to the atmosphere. The Rock Springs Uplift (RSU) in southwestern Wyoming has been identified as a candidate site for geologic sequestration of CO2. The RSU site contains two deep saline aquifers into which CO2 can be injected and stored: The Weber Sandstone and Upper Madison Limestone Formations. Sequestration of CO2 into these two formations is expected to displace approximately 700,000 gallons per day of highly saline water (avg. total dissolved solids ~95,000 mg L−1). For geologic sequestration to be successful, or even a practical option at the RSU site, the displaced water must be managed in such a way so that the carbon balance (CO2 sequestered - CO2 produced during treatment) is favorable and economics affordable. Three distinct water treatment alternatives were developed for managing and facilitating the beneficial reuse of the displaced water at the RSU site and included: desalination using forward osmosis, desalination using mechanical distillation and disposal using wind-aided evaporation. A present worth cost calculation for each alternative was developed which included the capital cost and the yearly operation and maintenance cost. The carbon footprint expected from each alternative was also evaluated. Both the present worth cost and carbon footprint should be considered when determining the most appropriate treatment alternative for this water.

This book investigates geological CO2 storage and its role in greenhouse gas emissions reduction, enhanced oil recovery, and environmentally responsible use of fossil fuels. Written for energy/environmental regulators at every level of government (federal, state, etc.), scientists/academics, representatives from the power and fossil energy sectors, NGOs, and other interested parties, this book uses the characterization of the Rock Springs Uplift site in Wyoming as an integrated case study to illustrate the application of geological CO2 storage science, principles, and theory in a real-world scenario.

This dissertation addresses a seismic reservoir characterization study and time-lapse feasibility of reservoir monitoring of carbon dioxide using seismic data, via rock physics models, global and local nonlinear inversions. It also aims to investigate the value of data integration, the relative impact of elastic and electrical rock physics model parameters on inverted petrophysical properties, and the feasibility of using resistivity data from time-lapse electromagnetic survey to monitor the displacement of carbon dioxide in the subsurface. This study focuses on the identification of target storage and sealing lithologies for a future carbon dioxide (CO2) monitoring project at the Rock Springs Uplift (RSU), Wyoming, USA. Seismic reservoir characterization aims to estimate reservoir rock and fluid properties such as porosity, fluid saturation, lithology, which are important properties for hydrocarbon exploration as well as carbon dioxide sequestration and monitoring projects. These petrophysical properties affect elastic attributes which in turn, affect the seismic response. Estimating reservoir properties therefore constitutes an inverse problem. Geophysical inverse problems are challenging because of the noise in recorded data, the nonlinearity of the inverse problem, the nonuniqueness of the solutions, etc. Depending upon the complexity of the problems, we can either use a local or a global optimization scheme to solve the specific problem. In this dissertation, we use a multilevel parallelization of a global prestack waveform inversion to three-dimensional seismic data with sparse well-information, to estimate subsurface elastic attributes like P-, S-wave velocity and density. This study contributes to the inversion of 3D large seismic data volume in an efficient computational time while providing high-resolution structural images of the subsurface compared to amplitude-variation-with-offset/angle (AVO/AVA) inversion. Following prestack waveform inversion, we use rock physics models to relate elastic attributes to reservoir properties and apply a local nonlinear least squares inversion scheme based on the trust-region algorithm, to invert elastic attributes for petrophysical properties like porosity and volumetric fractions of minerals. We apply this approach on well log data to validate the method, followed by applying it to the volumes of inverted elastic attributes obtained from prestack waveform inversion, to provide reservoir characterization away from the well. Because a carbon dioxide sequestration project is planned at the Rock Springs Uplift, we also investigate the feasibility of a time-lapse reservoir monitoring for the area using seismic data, by simulating the pressure and fluid effects on elastic velocities and synthetic seismograms. In the final part of this dissertation, we investigate the value of data integration by combining elastic and electrical attributes in a joint petrophysical inversion for reservoir rock and fluid properties. We illustrate the methodology using well log data sets from the Barents Sea and the Rock Springs Uplift, and show that the estimation of reservoir properties can be improved by combining multiple geophysical data. Despite the geological information we might have on a study area, there is often uncertainty in the choice of an adequate rock physics model and its input parameters not only at the well location, but also in areas with sparse well control. This study therefore helps understand the impact of such model parameters on inverted petrophysical properties and how it could affect reservoir interpretation. Next, we use a simple sharp interface model in order to provide a preliminary assessment of the extent of the CO2 plume, and thus address potential leakage risks. We also simulate the spatial distribution of CO2 after injection and compute corresponding resistivity datasets at different spatial resolutions, which we invert for water saturation. This synthetic study helps investigate the ability of monitoring the CO2 displacement using geophysical data.