Title:

Constant Viscosity Versus Temperature-Dependent Viscosity: Consequences for the Numerical Modeling of Enhanced Geothermal Systems

Authors:

Rita Esuru OKOROAFOR, Adam J. HAWKINS and Roland N. HORNE

Key Words:

fractures, geomechanics

Conference:

Stanford Geothermal Workshop

Year:

2020

Session:

Enhanced Geothermal Systems

Language:

English

Paper Number:

Okoroafor

File Size:

2699 KB

View File:

Abstract:

In an Enhanced Geothermal System (EGS), channeled-flow conditions in the subsurface can lead to premature thermal breakthrough due to the concentration of circulating fluids through “channels” of relatively low heat transfer area. Therefore, adequate modeling of EGS thermal performance requires proper accounting of spatial aperture variations within the two-dimensional plane of one or more target fractures. In the case of cold fluid injection, poroelastic effects and nonuniform temperature distributions can cause opening/closure of the fluid-filled aperture which can further affect thermal performance. In this study, a numerical experiment investigated the impact of thermo-hydro-mechanical coupling on EGS thermal performance. These effects were investigated for a single, heterogeneous fracture of nonuniform aperture and the evolution of the fracture aperture during cold water injection was simulated. In one scenario, constant water viscosity was assumed for the duration of the simulation while in another scenario, the variation of viscosity with changes in temperature was considered. The objective was to examine the impact of constant viscosity assumption in modeling EGS. From the study, it was observed that spatial aperture variations worsen flow channeling due to the thermal stresses and thus the predicted thermal performance of the EGS was impaired compared to the case where the thermal stresses were not taken into consideration. Moreover, the degree of impairment in the predicted EGS thermal performance was more significant in the case with temperature dependent viscosity than in the case of constant viscosity.


ec2-54-208-168-232.compute-1.amazonaws.com, you have accessed 0 records today.

Press the Back button in your browser, or search again.

Copyright 2020, Stanford Geothermal Program: Readers who download papers from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the original publisher.


Attend the nwxt Stanford Geothermal Workshop, click here for details.

Accessed by: ec2-54-208-168-232.compute-1.amazonaws.com (54.208.168.232)
Accessed: Friday 29th of March 2024 12:33:30 AM