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Image: Presenting the Summer 2015 work at AGU, December 2015. With mentor, Dr. Bill Carey, on the left.
Statement:
Statement:
While working with Bill Carey at Los Alamos National Laboratory (LANL) in the summer of 2015, I contributed to the Department of Energy (DOE) managed the Regional Carbon Sequestration Partnership (RCSP) that develops techniques to characterize promising C02 storage sites, efficient and durable technology for injection, and suitable regulation for future C02 storage. Within the RCSP, the Montana State UniversityBozeman led Big Sky Carbon Sequestration Project (BSCP) focuses on potential C02 storage sites throughout the Midwestern United States, including the 750 square mile Kevin Sunburst Dome in Montana. BSCSP intends to produce and then re-inject 1 million tonnes of CO₂ from the reservoir, in efforts to study the effects on the reservoir and watershed, the surrounding environment, and the local community.
While working with Bill Carey at Los Alamos National Laboratory (LANL) in the summer of 2015, I contributed to the Department of Energy (DOE) managed the Regional Carbon Sequestration Partnership (RCSP) that develops techniques to characterize promising C02 storage sites, efficient and durable technology for injection, and suitable regulation for future C02 storage. Within the RCSP, the Montana State UniversityBozeman led Big Sky Carbon Sequestration Project (BSCP) focuses on potential C02 storage sites throughout the Midwestern United States, including the 750 square mile Kevin Sunburst Dome in Montana. BSCSP intends to produce and then re-inject 1 million tonnes of CO₂ from the reservoir, in efforts to study the effects on the reservoir and watershed, the surrounding environment, and the local community.
My work at LANL involved characterizing the strength of Potlach anhydrite, the sealing rock formation that acts as a barrier preventing CO2 from migrating out of the Duperow Formation reservoir. We conducted dry, ambient temperature and pressure, uniaxial compression (UC) experiments on six anhydrite samples – three cored vertically and three cored horizontally. Our goal was to determine the Young’s modulus (E) – the extent of shortening that results from compression, Poisson’s ratio (υ) – the ratio of axial strain to lateral strain that accompanies shortening, and uniaxial compressive strength (UCS) - maximum stress a material endures before irreversible failure (fracture) of the rock. These are three common variables used in geomechanical engineering, and will be used in future fluid flow and geomechanical models to assess the capacity of the Potlatch anhydrite to trap sequestered CO₂ in the Kevin Dome.
My work at LANL involved characterizing the strength of Potlach anhydrite, the sealing rock formation that acts as a barrier preventing CO2 from migrating out of the Duperow Formation reservoir. We conducted dry, ambient temperature and pressure, uniaxial compression (UC) experiments on six anhydrite samples – three cored vertically and three cored horizontally. Our goal was to determine the Young’s modulus (E) – the extent of shortening that results from compression, Poisson’s ratio (υ) – the ratio of axial strain to lateral strain that accompanies shortening, and uniaxial compressive strength (UCS) - maximum stress a material endures before irreversible failure (fracture) of the rock. These are three common variables used in geomechanical engineering, and will be used in future fluid flow and geomechanical models to assess the capacity of the Potlatch anhydrite to trap sequestered CO₂ in the Kevin Dome.
Primary tasks and responsibilities:
Primary tasks and responsibilities:
I learned very quickly that you must be flexible and ingenuitive when working in a major research institution as experiments can often delayed due to unforeseen circumstances. The experiments were delayed a month as arrangements were made to use the load frame in the Materials Science division laboratory. During that time, I assisted the LANL microfluidic group as we developed a novel technique of laser etching fracture and pore networks in shale. I programed the etcher to create a series of engravings at various speeds and powers and learned how to operate the laser profilometer to measure depths of each engraving. I input and processed profilometer data in MatLab to assess the width, depth, and roughness of each engraving. After data analyses, I would test other parameters to properly etch simple fracture and pore geometries in efforts to calibrate an etching technique that would result in the smoothest and deepest fractures possible for microfluidic experiments.
I learned very quickly that you must be flexible and ingenuitive when working in a major research institution as experiments can often delayed due to unforeseen circumstances. The experiments were delayed a month as arrangements were made to use the load frame in the Materials Science division laboratory. During that time, I assisted the LANL microfluidic group as we developed a novel technique of laser etching fracture and pore networks in shale. I programed the etcher to create a series of engravings at various speeds and powers and learned how to operate the laser profilometer to measure depths of each engraving. I input and processed profilometer data in MatLab to assess the width, depth, and roughness of each engraving. After data analyses, I would test other parameters to properly etch simple fracture and pore geometries in efforts to calibrate an etching technique that would result in the smoothest and deepest fractures possible for microfluidic experiments.
Sample preparation and testing:
Sample preparation and testing:
I soon equipped the anhydrite core samples with strain gages for the uniaxial tests and learned fundamental electrical engineering concepts to understand how bridges and strain gages operate to properly detect stress through changes in resistivity. I assembled terminal pads, soldered leads, programmed the Instron load frame to complete the experiment at strain rates of 6.84 mm per second, and set up data acquisition. After deformation, I used the SEM and optical microscopy to characterize microdeformation. I found no evidence for the formation of slickenlines, mullions, or alignment of cleavage planes or pressure twinning that would suggest recrystallization processes during pre-failure stress buildup. Using optical microscopy, I studied whether grain and compositional contact affected how the anhydrite broke and found these had little to no effect on fracture network propagation. Through optical microscopy and X-Ray diffraction analyses, I confirmed that the bulk material was anhydrite and dolomite. These microscopic observations are key to understanding fracture propagation and geomaterial responses on a reservoir scale.
I soon equipped the anhydrite core samples with strain gages for the uniaxial tests and learned fundamental electrical engineering concepts to understand how bridges and strain gages operate to properly detect stress through changes in resistivity. I assembled terminal pads, soldered leads, programmed the Instron load frame to complete the experiment at strain rates of 6.84 mm per second, and set up data acquisition. After deformation, I used the SEM and optical microscopy to characterize microdeformation. I found no evidence for the formation of slickenlines, mullions, or alignment of cleavage planes or pressure twinning that would suggest recrystallization processes during pre-failure stress buildup. Using optical microscopy, I studied whether grain and compositional contact affected how the anhydrite broke and found these had little to no effect on fracture network propagation. Through optical microscopy and X-Ray diffraction analyses, I confirmed that the bulk material was anhydrite and dolomite. These microscopic observations are key to understanding fracture propagation and geomaterial responses on a reservoir scale.
Conclusions, Impact
Conclusions, Impact
Through analyzing the stress and strain data, I calculated an average UCS of 150.62 MPa, elastic moduli of 90.20 GPa, and a Poisson's ratio of 0.32. These three variables are critical to developing future geomechanical models that better assess the caprock properties and capabilities. I compared our parameters to those reported for other reservoirs assessed for CO2 sequestration both within and outside of the RCSP project. The Kevin Dome anhydrite is comparable to seals of other RCSP reservoirs including the dolostone and siltstone Eau Claire Formation of the Illinois Basin. The Potlach anhydrite is stronger and stiffer than the Gothic and Chimney rock shales of Paradox Basin. The anhydrite exhibits a higher UCS than the anhydrite caprock of the Permian Zechstein sequence capping potential CO₂ storage sites in the Netherlands and North Sea. These are several favorable characteristics of the Potlatch anhydrite that could potentially contribute to the Kevin Dome’s suitability for sequestering CO₂, although other variables still remain unknown to us at this time that also impact suitability (e.g. permeability, chemical compatibility, faulting, etc.).
Through analyzing the stress and strain data, I calculated an average UCS of 150.62 MPa, elastic moduli of 90.20 GPa, and a Poisson's ratio of 0.32. These three variables are critical to developing future geomechanical models that better assess the caprock properties and capabilities. I compared our parameters to those reported for other reservoirs assessed for CO2 sequestration both within and outside of the RCSP project. The Kevin Dome anhydrite is comparable to seals of other RCSP reservoirs including the dolostone and siltstone Eau Claire Formation of the Illinois Basin. The Potlach anhydrite is stronger and stiffer than the Gothic and Chimney rock shales of Paradox Basin. The anhydrite exhibits a higher UCS than the anhydrite caprock of the Permian Zechstein sequence capping potential CO₂ storage sites in the Netherlands and North Sea. These are several favorable characteristics of the Potlatch anhydrite that could potentially contribute to the Kevin Dome’s suitability for sequestering CO₂, although other variables still remain unknown to us at this time that also impact suitability (e.g. permeability, chemical compatibility, faulting, etc.).
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