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Title: Fractures in Subsurface Energy Applications: Coupling Geochemical and Geomechanical Processes
Authors: Spokas, Kasparas
Advisors: Peters, Catherine A
Contributors: Civil and Environmental Engineering Department
Keywords: Carbon Capture and Sequestration
Subjects: Environmental engineering
Issue Date: 2019
Publisher: Princeton, NJ : Princeton University
Abstract: Many engineering applications utilize the subsurface to store fluids, examples include carbon capture and sequestration, hydraulic fracturing, geothermal energy, and deep well disposal. A major risk of utilizing the subsurface are rock fractures that could allow for unwanted upward fluid migration or seismic activity. In this dissertation, I advance the understanding of how coupled geochemical and geomechanical processes affect the risks of leakage and seismicity of fractures, and present a novel geophyiscal signal of geochemical alteration that could be used for monitoring the degradation of fractures. In Chapter 2, reactive-transport modeling is used to demonstrate that the spatial pattern of less reactive mineral, not abundance, controls transmissivity evolution of rock fractures in heterogenous calcite-rich shales subject to reactive flow. Results show a banded mineral pattern creates persistent bottlenecks, prevents channelization, and stabilizes transmissivity. As a consequence, banded mineral variation may limit reactive evolution of fracture transmissivity and increase storage reliability. In Chapter 3, I present a novel two-stage experimental method with flow and mechanical shear to demonstrate that coupled geochemical and geomechanical processes could favorably seal fractures but also increase the likelihood of induced seismicity. During flow of acidic brine in laboratory experiments, reactive minerals selectively dissolved and created a porous layer. This layer collapsed under normal stress, filling the fracture with fine particles and decreasing permeability. However, in the laboratory iv experiments it was also observed that the frictional strength was reduced presumably because the layer of fine particles prevented the formation of interlocking microasperities. In Chapter 4, I use experimental methods to identify and demonstrate a novel seismic wave transmission method to detect signatures of chemical alteration of fracture surfaces. The porous layer that is created from selective mineral dissolution decreases the fracture specific stiffness, slowing the wave velocity, and lowering the maximum wave amplitude. Lastly, in Chapter 5 I broaden the scope of my dissertation and build a bioenergy with carbon capture and sequestration (BECCS) deployment optimization model across the continental United States. This model is used to showcase that the potential future negative emissions potential of BECCS is highly sensitive to the underlying biomass supply.
Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog:
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Civil and Environmental Engineering

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