The Effects of Secondary Trapping Mechanisms on Geologic Storage of Carbon Dioxide

The goal of this Dissertation is to further the understanding of secondary trapping mechanisms in geologic CO2 storage systems to improve storage design and security. This Dissertation takes the form of three chapters. The objective of the first chapter was to analyze the storage performance of supercritical and brine saturated CO2 injection strategies to determine their advantages and disadvantages on distribution and immobilization of CO2 and pressure buildup. Results showed dissolved CO2 injection was favorable in terms of storage security in all cases as it resulted in smaller areal extents on the caprock and did not migrate appreciably beyond the injection period. However, the distribution of dissolved CO2 was more influenced by formation heterogeneities than supercritical CO2. In cases with high permeability zones, the storage efficiency of dissolved CO2 was less than supercritical CO2. Supercritical CO2 injection was favorable in highly heterogeneous dipping formations where trapping was enhanced. The second chapter presents results from an experimental investigation of hysteresis in residual trapping and relative permeability of CO2 in a CO2/water system at 50°C and 9 MPa in a Berea sandstone core. Three flooding cycles were completed at a constant total volumetric flow rate by incrementally increasing and decreasing the fractional flow rates of supercritical CO2 and water. Results showed the CO2 saturations trapped during wetting-phase imbibition increased with the maximum CO2 saturations reached during each cycle. A linear model with coefficient 0.5 describes the nonwetting trapping relationship. The CO2 relative permeability data can be represented well by making a minor modification to the Van Genuchten-Burdine relative permeability data to account for hysteresis. The third chapter demonstrates a practical approach to optimizing CO2 storage design by determining economically efficient injection strategies that increase storage security through enhanced secondary trapping mechanisms. Optimizations considered 5 different water/CO2 co-injection strategies. These strategies were all compared to a base case of standard supercritical CO2 injection. Results showed SWAG, WAG, and water flush strategies reduced costs and increased secondary CO2 trapping. Dissolved CO2 injection was unable to reduce the cost, but trapped the most CO2 by secondary mechanisms of any method. Ultimately, results may be used to design CO2 injection strategies that take advantage of CO2 trapping behavior at targeted depths

Demonstration of optimization techniques for groundwater plume remediation using iTOUGH2

We examined the potential use of standard optimization algorithms as implemented in the inverse modeling code iTOUGH2 (Finsterle, 1999abc) for the solution of aquifer remediation problems. Costs for the removal of dissolved or free-phase contaminants depend on aquifer properties, the chosen remediation technology, and operational parameters (such as number of wells drilled and pumping rates). A cost function must be formulated that may include actual costs and hypothetical penalty costs for incomplete cleanup; the total cost function is therefore a measure of the overall effectiveness and efficiency of the proposed remediation scenario. The cost function is then minimized by automatically adjusting certain decision or operational parameters. We evaluate the impact of these operational parameters on remediation using a three-phase, three-component flow and transport simulator, which is linked to nonlinear optimization routines. We demonstrate that the methods developed for automatic model calibration are capable of minimizing arbitrary cost functions. An example of co-injection of air and steam makes evident the need for coupling optimization routines with an accurate state-of-the-art process simulator. Simplified models are likely to miss significant system behaviors such as increased downward mobilization due to recondensation of contaminants during steam flooding, which can be partly suppressed by the co-injection of air

Basic Research Needs for Geosciences: Facilitating 21st Century Energy Systems

Executive Summary Serious challenges must be faced in this century as the world seeks to meet global energy needs and at the same time reduce emissions of greenhouse gases to the atmosphere. Even with a growing energy supply from alternative sources, fossil carbon resources will remain in heavy use and will generate large volumes of carbon dioxide (CO2). To reduce the atmospheric impact of this fossil energy use, it is necessary to capture and sequester a substantial fraction of the produced CO2. Subsurface geologic formations offer a potential location for long-term storage of the requisite large volumes of CO2. Nuclear energy resources could also reduce use of carbon-based fuels and CO2 generation, especially if nuclear energy capacity is greatly increased. Nuclear power generation results in spent nuclear fuel and other radioactive materials that also must be sequestered underground. Hence, regardless of technology choices, there will be major increases in the demand to store materials underground in large quantities, for long times, and with increasing efficiency and safety margins. Rock formations are composed of complex natural materials and were not designed by nature as storage vaults. If new energy technologies are to be developed in a timely fashion while ensuring public safety, fundamental improvements are needed in our understanding of how these rock formations will perform as storage systems. This report describes the scientific challenges associated with geologic sequestration of large volumes of carbon dioxide for hundreds of years, and also addresses the geoscientific aspects of safely storing nuclear waste materials for thousands to hundreds of thousands of years. The fundamental crosscutting challenge is to understand the properties and processes associated with complex and heterogeneous subsurface mineral assemblages comprising porous rock formations, and the equally complex fluids that may reside within and flow through those formations. The relevant physical and chemical interactions occur on spatial scales that range from those of atoms, molecules, and mineral surfaces, up to tens of kilometers, and time scales that range from picoseconds to millennia and longer. To predict with confidence the transport and fate of either CO2 or the various components of stored nuclear materials, we need to learn to better describe fundamental atomic, molecular, and biological processes, and to translate those microscale descriptions into macroscopic properties of materials and fluids. We also need fundamental advances in the ability to simulate multiscale systems as they are perturbed during sequestration activities and for very long times afterward, and to monitor those systems in real time with increasing spatial and temporal resolution. The ultimate objective is to predict accurately the performance of the subsurface fluid-rock storage systems, and to verify enough of the predicted performance with direct observations to build confidence that the systems will meet their design targets as well as environmental protection goals. The report summarizes the results and conclusions of a Workshop on Basic Research Needs for Geosciences held in February 2007. Five panels met, resulting in four Panel Reports, three Grand Challenges, six Priority Research Directions, and three Crosscutting Research Issues. The Grand Challenges differ from the Priority Research Directions in that the former describe broader, long-term objectives while the latter are more focused

Basic Research Needs for Geosciences: Facilitating 21st Century Energy Systems

To identify research areas in geosciences, such as behavior of multiphase fluid-solid systems on a variety of scales, chemical migration processes in geologic media, characterization of geologic systems, and modeling and simulation of geologic systems, needed for improved energy systems

Earth Sciences Division Research Summaries 2006-2007

Research in earth and atmospheric sciences has become increasingly important in light of the energy, climate change, and other environmental issues facing the United States and the world. The development of new energy resources other than fossil hydrocarbons, the safe disposal of nuclear waste and greenhouse gases, and a detailed understanding of the climatic consequences of our energy choices are all critical to meeting energy needs while ensuring environmental safety. The cleanup of underground contamination and the preservation and management of water supplies continue to provide challenges, as they will for generations into the future. To address the critical energy and environmental issues requires continuing advances in our knowledge of Earth systems and our ability to translate that knowledge into new technologies. The fundamental Earth science research common to energy and environmental issues largely involves the physics, chemistry, and biology of fluids in and on the Earth. To manage Earth fluids requires the ability to understand their properties and behavior at the most fundamental molecular level, as well as prediction, characterization, imaging, and manipulation of those fluids and their behavior in real Earth reservoirs. The broad range of disciplinary expertise, the huge range of spatial and time scales, and the need to integrate theoretical, computational, laboratory and field research, represent both the challenge and the excitement of Earth science research. The Earth Sciences Division (ESD) of the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab) is committed to addressing the key scientific and technical challenges that are needed to secure our energy future in an environmentally responsibly way. Our staff of over 200 scientists, UC Berkeley faculty, support staff and guests perform world-acclaimed fundamental research in hydrogeology and reservoir engineering, geophysics and geomechanics, geochemistry, microbial ecology, climate systems, and environmental engineering. Building on this scientific foundation, we also perform applied earth science research and technology development to support DOE in a number of its program areas. We currently organize our efforts in the following Division Programs: Fundamental and Exploratory Research--fundamental research in geochemistry, geophysics, and hydrology to provide a basis for new and improved energy and environmental technologies; Climate and Carbon Sciences--carbon cycling in the terrestrial biosphere and oceans, and global and regional climate modeling, are the cornerstones of a major developing divisional research thrust related to understanding and mitigating the effects of increased greenhouse gas concentrations in the atmosphere; Energy Resources--collaborative projects with industry to develop or improve technologies for the exploration and production of oil, gas, and geothermal reservoirs, and for the development of bioenergy; Environmental Remediation and Water Resources--innovative technologies for locating, containing, and remediating metals, radionuclides, chlorinated solvents, and energy-related contaminants in soils and groundwaters; Geologic Carbon Sequestration--development and testing of methods for introducing carbon dioxide to subsurface geologic reservoirs, and predicting and monitoring its subsequent migration; and Nuclear Waste and Energy--theoretical, experimental, and simulation studies of the unsaturated zone at Yucca Mountain, Nevada. These programs draw from each of ESD's disciplinary departments: Climate Science, Ecology, Geochemistry, Geophysics, and Hydrogeology. Short descriptions of these departments are provided as introductory material. In this document, we present summaries of selected current research projects. While it is not a complete accounting, the projects described here are representative of the nature and breadth of the ESD research effort. We are proud of our scientific accomplishments and we hope that you will find this material useful and exciting. A list of publications for the period from January 2006 to June 2007, along with a listing of our personnel, are also appended. Any comments on our research are appreciated and can be sent to me personally