Coupled thermo-hydro-mechanical analysis of stimulation and production for fractured geothermal reservoirs

Sanbai Li, Xia-Ting Feng, Dongxiao Zhang and Huiying Tang

Applied Energy, 2019, vol. 247, issue C, 40-59

Abstract: Commercial development of enhanced geothermal systems in low-permeability rocks relies on fracturing treatments to create complex-fracture networks and an appropriate circulation strategy to maintain high flow rates at sufficiently high temperatures. However, it remains challenging to model complex-fracture propagation and heat energy extraction as a whole. This paper develops a fully coupled thermo-hydro-mechanical model to simulate reservoir stimulation and heat production in naturally fractured geothermal reservoirs. The proposed model is validated against a widely used model, TOUGH2, concerning heat sweep in a vertical fracture. This model is then applied to study multi-staged fracturing and geothermal extraction related to a doublet of horizontal wells. The hydro-geomechanical properties are chosen from the Soultz geothermal reservoir at a depth of approximately 3600 m. Numerical results demonstrate that: (1) mixed tensile and shear fracturing can constitute an important stimulation mechanism for naturally fractured geothermal reservoirs; (2) well interlinked, zigzag artificial fractures between injection and production wells readily lead to channeling flow; (3) keeping a segment of horizontal wells open and placing them further apart are beneficial to the formation of sufficiently diffuse flow pathways; (4) increasing well spacing tends to improve thermal performance; however, for the case of a one-stage opening, the improvement of heat sweep efficiency is not significant; and (5) an alternating circulation scheme could achieve superior thermal performance. This study establishes an effective modeling workflow for the design and optimization of naturally fractured geothermal reservoirs, and provides an integrated modeling framework for evaluating recoverable energy potential from geothermal reservoirs.

Keywords: Enhanced geothermal system; Hydraulic fracturing; Thermo-hydro-mechanical model; Complex-fracture propagation; Shear stimulation (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (37)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0306261919306695
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:247:y:2019:i:c:p:40-59

Ordering information: This journal article can be ordered from
http://www.elsevier.com/wps/find/journaldescription.cws_home/405891/bibliographic
http://www.elsevier. ... 405891/bibliographic

DOI: 10.1016/j.apenergy.2019.04.036

Access Statistics for this article

Applied Energy is currently edited by J. Yan

More articles in Applied Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().