Fracture conductivity of a bauxite-propped geothermal system

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Publication Type thesis
School or College College of Engineering
Department Chemical Engineering
Author Stoddard, Trevor Ryan
Title Fracture conductivity of a bauxite-propped geothermal system
Date 2013-12
Description Enhanced Geothermal Systems (EGS) are geothermal resources that are developed through hydraulic stimulation. Inadequate permeability and production from natural fractures and pores can be overcome via injection of cold water below fracturing pressure, by conventional hydraulic fracturing, or by some cyclic combination of these processes. At low injection rates or where thermal fracturing is being exploited, shearing of pre-existing weaknesses and potentially developing virgin fractures is envisioned to provide permeable, self-propped pathways. Alternatively, injection at pressures substantially above the minimum principal stress can also hydraulically connect, reopen, or create fractures and also possibly induce shearing (as known from microseismic monitoring). The heat from this artificially fractured reservoir is subsequently transferred to the injected fluid and extracted through a production well. Conventional steam turbines or a binary cycle power plants can be employed for electric generation. The technical challenges in developing EGS reservoirs are substantial and include controlling fracture direction and morphology, establishing an adequate heat transfer surface area, and maintaining conductivity. The latter was the focal point of investigation. It is commonly assumed that that the induced fractures will fail by shear and be self-propping. If tensile fractures are generated, they need to be explicitly held open by proppant (and it needs to be ensured that the proppant is not produced back into the wellbore). The conductivity of bauxite-propped fractures over extended periods of time and at elevated temperatures were measured in laboratory tests in order to assess the temporal and thermal dependency of conductivity in a typical surrogate fracture.
Type Text
Publisher University of Utah
Subject EGS; Geothermal; Proppant
Dissertation Institution University of Utah
Dissertation Name Master of Science
Language eng
Rights Management Copyright © Trevor Ryan Stoddard 2013
Format Medium application/pdf
Format Extent 19,821,887 bytes
Identifier etd3/id/2636
ARK ark:/87278/s6671ncz
Setname ir_etd
Date Created 2014-01-14
Date Modified 2018-03-27
ID 196211
Reference URL