Modelling an unconventional closed-loop deep borehole heat exchanger (DBHE): sensitivity analysis on the Newberry volcanic setting

Doran, H. R. , Renaud, T., Falcone, G. , Pan, L. and Verdin, P. G. (2021) Modelling an unconventional closed-loop deep borehole heat exchanger (DBHE): sensitivity analysis on the Newberry volcanic setting. Geothermal Energy, 9, 4. (doi: 10.1186/s40517-021-00185-0)

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Abstract

Alternative (unconventional) deep geothermal designs are needed to provide a secure and efficient geothermal energy supply. An in-depth sensitivity analysis was investigated considering a deep borehole closed-loop heat exchanger (DBHE) to overcome the current limitations of deep EGS. A T2Well/EOS1 model previously calibrated on an experimental DBHE in Hawaii was adapted to the current NWG 55-29 well at the Newberry volcano site in Central Oregon. A sensitivity analysis was carried out, including parameters such as the working fluid mass flow rate, the casing and cement thermal properties, and the wellbore radii dimensions. The results conclude the highest energy flow rate to be 1.5 MW, after an annulus radii increase and an imposed mass flow rate of 5 kg/s. At 3 kg/s, the DBHE yielded an energy flow rate a factor of 3.5 lower than the NWG 55-29 conventional design. Despite this loss, the sensitivity analysis allows an assessment of the key thermodynamics within the wellbore and provides a valuable insight into how heat is lost/gained throughout the system. This analysis was performed under the assumption of subcritical conditions, and could aid the development of unconventional designs within future EGS work like the Newberry Deep Drilling Project (NDDP). Requirements for further software development are briefly discussed, which would facilitate the modelling of unconventional geothermal wells in supercritical systems to support EGS projects that could extend to deeper depths.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Falcone, Professor Gioia and Doran, Hannah
Authors: Doran, H. R., Renaud, T., Falcone, G., Pan, L., and Verdin, P. G.
College/School:College of Science and Engineering
College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Geothermal Energy
Publisher:Springer
ISSN:2195-9706
ISSN (Online):2195-9706
Published Online:15 February 2021
Copyright Holders:Copyright © The Author(s) 2021
First Published:First published in Geothermal Energy 9:4
Publisher Policy:Reproduced under a Creative Commons license
Data DOI:10.5525/gla.researchdata.1111

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
305200DTP 2018-19 University of GlasgowMary Beth KneafseyEngineering and Physical Sciences Research Council (EPSRC)EP/R513222/1MVLS - Graduate School