Researchers at Montana State University are building and testing a mesoscale (~1 m-diameter), high-pressure rock test system; developing a biomineralization seal experimental protocol; and creating biomineralization seals in different rock types and under actual field conditions. The integrity of the seals—both within the wellbore and between the wellbore and the geologic formation—is critical in minimizing CO2 leakage through formation fractures or within the wellbore during CO2 injection operations. The project is designed to study biomineralization processes that will be effective at sealing flow or leakage pathways near wellbores in subsurface environments (Figure 1). The concept proposed for enhancing geologic carbon storage is based on the use of engineered microbial biofilms capable of biomineralization. The engineered biomineralization process produces biofilm and mineral deposits that reduce the permeability of geologic media while modifying the geochemistry of brines to enhance CO2 solubility and mineral precipitation. This process can be targeted to the geologic media surrounding carbon storage injection wells to provide long-term sealing of preferential CO2 leakage pathways. Because the fluids involved in biofilm formation and biomineralization are low viscosity aqueous solutions, this technology has the potential to seal small aperture leaks or the porous rock itself, potentially providing a leakage mitigation technique that can address issues problematic for cement use.
The research is investigating whether mineral deposits can be formed at a field scale under conditions that mimic subsurface reservoirs and whether they can be kept uniform over relevant distances. The project is also determining whether sealing in disturbed rock-cement and cement-well bore interfaces can be achieved through biomineral deposits that remain stable when exposed to injection and formation fluids. This project is examining these effects by creating a large, tightly controlled testing facility that replicates actual field conditions and uses it to conduct proof-of-principle testing and methodology development for biomineralization.
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. This research is developing a biomineralization-based technology for sealing preferential flow pathways in the vicinity of injection wells and help to maximize injectivity and containment effectiveness.
This project will benefit carbon storage in geologic reservoirs by analyzing how borehole seal integrity can be improved in multiple geologic reservoir types. Successful project research will advance the development of an optimized protocol for construction and evaluation of biomineralization seals of small aperture leaks at field sites for geologic CO2 carbon storage. Improving wellbore integrity helps ensure the carbon storage programmatic goal of demonstrating 99 percent storage permanence and improves the efficiency of storage operations.
The goals of the project are to use the results from focused laboratory studies to demonstrate that (1) mineral deposits can be formed at a field-relevant scale under environmental conditions appropriate to subsurface reservoirs; (2) the mineral deposition can be kept uniform over relevant distances; (3) the degree of sealing in disturbed rock, cement, and cement-well bore interfaces reaches an acceptable level; and (4) the biomineral deposits remain stable when exposed to brine and supercritical CO2.
The project consists of three primary objectives:
Assemble a mesoscale high-pressure rock test system.
Development of a biomineralization seal experimental protocol.
Creation of biomineralization seals in different rock types and under actual field conditions.
The project will be conducted through applied research into the theoretical and applied aspects of biomineralization for different lithologies and at different conditions (environmental parameters) in multiple geologic reservoir types.
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