Effect of water-cooling shock on fracture initiation and morphology of high-temperature granite: Application of hydraulic fracturing to enhanced geothermal systems

Yi Xue, Shuai Liu, Junrui Chai, Jia Liu, P.G. Ranjith, Chengzheng Cai, Feng Gao and Xue Bai

Applied Energy, 2023, vol. 337, issue C, No S0306261923002222

Abstract: Deep geothermal energy exploitation is primarily accomplished using an enhanced geothermal system (EGS) to extract heat from hot dry rock (HDR). The use of hydraulic fracturing technology to build large-scale fracture networks is essential for improving the EGS heat extraction efficiency. Water-cooling shock on high-temperature rock degrades the mechanical properties of the rock while increasing the fracturing effect of HDR. A thermal–hydraulic–mechanical coupling model is proposed herein to investigate the effect of water-cooling shock on fracture initiation and morphology in HDR hydraulic fracturing. The validity of the coupling model is confirmed using theoretical analytical solutions and physical experimental results, such as hydraulic fracturing experiments on high-temperature granite, as well as analytical solutions for the stress shadow effect and fracture initiation pressure. The numerical simulation is performed using a coupling model to investigate the characteristics of fracture propagation and damage evolution during the HDR hydraulic fracturing process as well as to investigate the fracturing effect of water-cooling shock on high-temperature rock. Finally, the effects of initial rock temperature, in-situ stress, and heat transfer coefficient on fracture morphology are investigated. The results show that the combined effects of tensile strength deterioration water-cooling shock, thermal stress caused by cold shrinkage, and pore water pressure are primarily responsible for the initiation and propagation of hydraulic fractures. The water-cooling shock can considerably reduce the fracture initiation pressure, induce more secondary fractures, and form more complex fracture networks. The initial temperature and heat transfer coefficient of the rock affect the thermal stress and tensile strength deterioration. The formation of an intricate fracture network can be aided by a high initial rock temperature, a large surface heat transfer coefficient, and small in-situ stress differences.

Keywords: Hot dry rock; Hydraulic fracturing; Water-cooling shock; Deterioration of rock mechanics parameters; Thermal–hydraulic–mechanical coupling (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (7)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0306261923002222
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:337:y:2023:i:c:s0306261923002222

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.2023.120858

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 ().