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Optimal Geological Environments for Carbon Dioxide Disposal in Saline Aquifers in the United States

Description: Recent research and applications have demonstrated technologically feasible methods, defined costs, and modeled processes needed to sequester carbon dioxide (CO{sub 2}) in saline-water-bearing formations (aquifers). One of the simplifying assumptions used in previous modeling efforts is the effect of real stratigraphic complexity on transport and trapping in saline aquifers. In this study we have developed and applied criteria for characterizing saline aquifers for very long-term sequestration of CO{sub 2}. The purpose of this pilot study is to demonstrate a methodology for optimizing matches between CO{sub 2} sources and nearby saline formations that can be used for sequestration. This project identified 14 geologic properties used to prospect for optimal locations for CO{sub 2} sequestration in saline-water-bearing formations. For this demonstration, we digitized maps showing properties of saline formations and used analytical tools in a geographic information system (GIS) to extract areas that meet variably specified prototype criteria for CO{sub 2} sequestration sites. Through geologic models, realistic aquifer properties such as discontinuous sand-body geometry are determined and can be used to add realistic hydrologic properties to future simulations. This approach facilitates refining the search for a best-fit saline host formation as our understanding of the most effective ways to implement sequestration proceeds. Formations where there has been significant drilling for oil and gas resources as well as extensive characterization of formations for deep-well injection and waste disposal sites can be described in detail. Information to describe formation properties can be inferred from poorly known saline formations using geologic models in a play approach. Resulting data sets are less detailed than in well-described examples but serve as an effective screening tool to identify prospects for more detailed work.
Date: February 1, 1999
Creator: Hovorka, Susan D.
Partner: UNT Libraries Government Documents Department

Characterization of bedded salt for storage caverns -- A case study from the Midland Basin, Texas

Description: The geometry of Permian bedding salt in the Midland Basin is a product of interaction between depositional facies and postdepositional modification by salt dissolution. Mapping high-frequency cycle patterns in cross section and map view using wireline logs documents the salt geometry. Geologically based interpretation of depositional and dissolution processes provides a powerful tool for mapping and geometry of salt to assess the suitability of sites for development of solution-mined storage caverns. In addition, this process-based description of salt geometry complements existing data about the evolution of one of the best-known sedimentary basins in the world, and can serve as a genetic model to assist in interpreting other salts.
Date: June 13, 2000
Creator: Hovorka, Susan D. & Nava, Robin
Partner: UNT Libraries Government Documents Department

Testing efficiency of storage in the subsurface: frio brine pilot experiment

Description: Can we demonstrate that subsurface storage is an effective method of reducing emissions of CO2 to the atmosphere? The Frio Brine Pilot Experiment is designed to test storage performance of a typical subsurface environment in an area where large-volume sources and sinks are abundant, near Houston, Texas, USA. We employed extensive pre-experiment characterization and modeling to identify significant factors that increase or decrease risk of leakage from the injection zone. We then designed the experiment to focus on those factors, as well as to test for presence or absence of events that are not expected. A fully developed reservoir model of heterogeneous reworked fluvial sandstones of the Frio Formation documents three-dimensional compartmentalization of the injection horizon by faulting associated with salt-dome intrusion and growth. Modeling using the TOUGH2 simulator showed that a significant source of uncertainty for subsurface performance of injected CO2 is residual CO2 saturation during storage. If initial displacement of water during injection is efficient and capillary effects create the expected residual saturation of 30 percent CO2, the volume occupied by the plume will be limited, and long-term storage can be expected even in an open system. If, however, during injection, CO2 moves out from the injection well along high-permeability pathways, it may not contact most pores, and residual saturation will have a smaller effect on storage. Our experiment is therefore designed to monitor plume geometry and CO2 saturation near the injection well and closely spaced observation well. Leakage out of the injection zone as a result of well engineering or other flaws in the seal is also monitored in the sandstone immediately overlying the injection zone and at the surface using multiple techniques. Permitting strategies include cooperation among two State agencies, as well as Federal NEPA assessment, because of the innovative aspects of the experiment.
Date: June 30, 2004
Creator: Hovorka, Susan D.; Doughty, Christine & Holtz, Mark
Partner: UNT Libraries Government Documents Department

Capacity investigation of brine-bearing sands of the Fwwm formation for geologic sequestration of CO{sub 2}

Description: The capacity of fluvial brine-bearing formations to sequester CO{sub 2} is investigated using numerical simulations of CO{sub 2} injection and storage. Capacity is defined as the volume fraction of the subsurface available for CO{sub 2} storage and is conceptualized as a product of factors that account for two-phase flow and transport processes, formation geometry, formation heterogeneity, and formation porosity. The space and time domains used to define capacity must be chosen with care to obtain meaningful results, especially when comparing different authors' work. Physical factors that impact capacity include permeability anisotropy and relative permeability to CO{sub 2}, brine/CO{sub 2} density and viscosity ratios, the shape of the trapping structure, formation porosity and the presence of low-permeability layering.
Date: May 1, 2001
Creator: Doughty, Christine; Pruess, Karsten; Benson, Sally M.; Hovorka, Susan D.; Knox, Paul R. & Green, Christopher T.
Partner: UNT Libraries Government Documents Department

National Uranium Resource Evaluation: Seguin Quadrangle, Texas

Description: From Introduction: "The Seguin Quadrangle, Texas, was evaluated to a depth of 1500 m (5,000 ft) to identify geologic units and delineate areas that exhibit characteristics favorable for the occurrence of uranium deposits. Each geologic environment was categorized as favorable, unfavorable, or unevaluated for uranium deposits, based on recognition criteria obtained from the study of significant uranium districts worldwide (Mickle and Matherws, eds.1978)."
Date: July 1982
Creator: Droddy, Marvin J. & Hovorka, Susan D.
Location Info:
Partner: UNT Libraries Government Documents Department

TheU-Tube: A Novel System for Acquiring Borehole Fluid Samplesfrom a Deep Geologic CO2 Sequestration Experiment

Description: A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase (supercritical CO2-brine) fluid from 1.5 km depth. The datasets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydro-geochemical issues affecting CO2 sequestration in brine-filled formations. While the basic premise underlying the U-Tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO2. A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO2. The U-Tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO2 plume, and on-site analysis revealed rapid changes in geochemical conditions.
Date: March 17, 2005
Creator: Freifeld, Barry M.; Trautz, Robert C.; Kharaka, Yousif K.; Phelps, Tommy J.; Myer, Larry R.; Hovorka, Susan D. et al.
Partner: UNT Libraries Government Documents Department