Researchers at Clemson University and its partners are evaluating the feasibility of using wellbore deformations to assess the changing conditions of geologic storage formations, confining zones, and well boreholes (Figure 1). Wellbores can deform in response to the injection or recovery of fluid. In extreme cases, the deformation is catastrophic and the well can be compromised. In routine cases, the small elastic deformation that accompanies injection or recovery has the potential to be an important diagnostic tool that can be used to improve the efficiency and safety of carbon storage. Wellbores can potentially deform during carbon storage operations, and effective monitoring of this process can be used to detect early precursors to fracturing within the injection formation, induced faulting, and failure of wellbore seals so they can be addressed before becoming catastrophic. These results will improve the characterization of geologic storage formations, confining zone compressibility, and pressure-dependent permeability, in addition to the distribution of structural deformation and other stratigraphic or structural differences in multiple geologic formation types. The results will improve well borehole characterization, including improvements in the understanding of the bond and integrity between the well casing, the cemented or grouted well annulus (the space between the well casing and the perimeter of the borehole), and the geologic formation itself.
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. The project performs work to address the need for additional research to further evaluate the role that wellbore and storage formation integrity plays in the geologic storage of CO2.
This project benefits carbon storage in geologic formations by developing a new technique that will improve both geologic formation characterization and in situ monitoring. This new technique could also improve the characterization of geologic storage formations, confining zone compressibility, and pressure-driven permeability, as well as the distribution of structural deformation (i.e., fractures) and other heterogeneities in a wide range of geologic formation types.
Moreover, the new technique will improve the understanding and mechanical characterization of the well bore itself, including the bonds between the well casing, grout or cement, and the geologic formation. If used during carbon storage operations, wellbore deformation has the potential to detect the precursors to hydraulic fractures in either the geologic storage formation or the wellbore annulus. This research will demonstrate the ability to monitor and interpret wellbore displacements and will thus improve the safety and effectiveness of carbon storage while reducing its costs, which forwards the Carbon Storage Program goals of demonstrating 99 percent storage permanence and improving the efficiency of storage operations.
The objective of this project is to evaluate the feasibility of measuring and interpreting wellbore deformations under conditions anticipated for geologic carbon storage, with the ultimate goal of establishing the necessary background for a field demonstration. This will be accomplished by developing the knowledge required to anticipate the mechanical response, interpret the results of deformation measurements, and develop the equipment to take the required field measurements.
The project consists of three primary goals:
Characterization of wellbore deformation under conditions anticipated for use in geologic carbon storage.
Development of identification and evaluation techniques for interpreting the results of simultaneous measurements of displacement and pressures during well testing or operation.
Evaluation of the capabilities of downhole instruments.
The project is being conducted by applying a broad range of expertise in theoretical and applied aspects of hydromechanical well testing, geomechanics, model inversion, and instrumentation. Deliverables include reports and journal papers describing simulation, interpretation, and instrumentation required for the proposed technique.
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