Researchers at the Colorado School of Mines and the Lawrence Berkeley National Laboratory are analyzing CO2 trapping data sets to verify models that simulate CO2 trapping mechanisms in heterogeneous porous reservoirs at an intermediate to large scale. The basic processes of CO2 trapping are not easily understood through field testing, so a set of multi-scale laboratory tests will be conducted to further analyze CO2 trapping mechanisms. The focus of this research will be to analyze capillary (Figure 1) and dissolution trapping (Figure 2) mechanisms since they are considered to be the most relevant processes facilitating permanent CO2 storage in the absence of geologic structural traps; the efficiency of capillary and dissolution trapping mechanisms is considered to be strongly affected by the heterogeneity of the storage formation. Capillary trapping involves CO2 being isolated in pore-space bubbles surrounded by formation water, and dissolution trapping involves CO2 being dissolved in the formation fluid. This project will supplement previous research with multi-phase injection flow experiments conducted at various scales. Small-scale experiments will identify the fundamental trapping processes in homogeneous systems and provide supplemental data for use in intermediate- and large-scale models to capture the capillary and dissolution trapping processes in storage media with pore-scale heterogeneities.
The overall goal of the Department of Energy’s (DOE) Carbon Storage Program is to develop and advance technologies that will significantly improve the effectiveness of geologic carbon storage, reduce the cost of implementation, and prepare for widespread commercial deployment between 2020 and 2030. Research conducted to develop these technologies will ensure safe and permanent storage of carbon dioxide (CO2) to reduce greenhouse gas (GHG) emissions without adversely affecting energy use or hindering economic growth. Geologic carbon storage involves the injection of CO2 into underground formations that have the ability to securely contain the CO2 permanently. Technologies being developed for geologic carbon storage are focused on five storage types: oil and gas reservoirs, saline formations, unmineable coal seams, basalts, and organic-rich shales. Technologies being developed will work towards meeting carbon storage programmatic goals of (1) estimating CO2 storage capacity +/- 30 percent in geologic formations; (2) ensuring 99 percent storage permanence; (3) improving efficiency of storage operations; and (4) developing Best Practices Manuals. These technologies will lead to future CO2 management for coal-based electric power generating facilities and other industrial CO2 emitters by enabling the storage and utilization of CO2 in all storage types. The DOE Carbon Storage Program encompasses five Technology Areas: (1) Geologic Storage and Simulation and Risk Assessment (GSRA), (2) Monitoring, Verification, Accounting (MVA) and Assessment, (3) CO2 Use and Re-Use, (4) Regional Carbon Sequestration Partnerships (RCSP), and (5) Focus Area for Sequestration Science. The first three Technology Areas comprise the Core Research and Development (R&D) that includes studies ranging from applied laboratory to pilot-scale research focused on developing new technologies and systems for GHG mitigation through carbon storage. This project is part of the Core R&D GSRA Technology Area and works to develop technologies and simulation tools to ensure secure geologic storage of CO2. It is critical that these technologies are available to aid in characterizing geologic formations before CO2-injection takes place in order to predict the CO2 storage resource and develop CO2 injection techniques that achieve optimal use of the pore space in the reservoir and avoid fracturing the confining zone (caprock). The program’s R&D strategy includes adapting and applying existing technologies that can be utilized in the next five years, while concurrently developing innovative and advanced technologies that will be deployed in the decade beyond. Laboratory investigations dealing with CO2 injections and flow patterns have been conducted on a small-scale in homogeneous reservoirs. More research is needed to further evaluate CO2 injection and flow modeling in heterogeneous reservoirs, so more accurate containment estimates can be made for the geologic storage of CO2. This project aims to advance the knowledge of CO2 flow modeling and trapping mechanisms in heterogeneous reservoirs. This project will benefit carbon storage in geologic reservoirs by providing greater insight into how CO2 can be trapped by capillary and dissolution mechanisms in heterogeneous formations. The new data set generated by these intermediate-scale simulations could also improve existing trapping mechanism simulation modeling, as current data sets have only evaluated trapping mechanisms in homogeneous micro-scale media. More precise modeling will improve the understanding and characterization of heterogeneous geologic reservoirs associated with CO2 injection. This research will demonstrate the ability of heterogeneous reservoirs to contain CO2 in a more effective manner, which could also reduce the cost of carbon storage operations. These benefits will support the Carbon Storage Programmatic goals of demonstrating 99 percent storage permanence, improving efficiency of storage operations and enhancing the ability to predict geologic storage capacity to within +/- 30 percent. Goals/Objectives
The objective of this project is to improve the understanding of how CO2 trapping mechanisms are affected by the heterogeneity of the reservoir formation, with the ultimate goal of improving larger-scale trapping mechanism models. The findings of this work will contribute towards the objectives of NETL’s Carbon Storage Program research to develop technologies that cost-effectively and safely store and monitor CO2 in geologic formations and to ensure storage permanence. Developed approach and technologies in this project specifically contribute to the Carbon Storage Program’s effort of supporting industries’ ability to predict geologic storage capacity to within +/- 30 percent. This will be accomplished by conducting laboratory experiments focusing on flow in heterogeneous media to improve the understanding of the fundamental processes of CO2 trapping mechanisms. The project will consist of three primary objectives:
Generation of a comprehensive data set using intermediate-scale test tanks to simulate multi-phase flow for the purpose of investigating the effect of capillary trapping in heterogeneous reservoirs.
Generation of a comprehensive data set using intermediate-scale test tanks to simulate the dissolution of partially soluble fluids to analyze the effect of dissolution trapping in heterogeneous reservoirs.
Evaluation of whether or not existing modeling codes can mimic the processes observed in the test tanks.
The project will be conducted by applying previous expertise in theoretical and applied aspects of multi-phase fluid flow to evaluate the effects of preferential flow and intra-layer mixing in heterogeneous reservoirs. Once the research is completed, a comprehensive data set that can be used to improve predictive tools for CO2 storage will be generated.
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