Study on fracture evolution model of the enhanced geothermal system under thermal-hydraulic-chemical-deformation coupling

Journal article (2023)

Authors

Jiayan Ji China University of Petroleum - Beijing
Xianzhi Song China University of Petroleum - Beijing
G. Song China University of Petroleum - Beijing
Fuqiang Xu China University of Petroleum - Beijing
Yu Shi Southwest Jiaotong University, China University of Petroleum - Beijing
Zehao Lv Petrochina Research Institute of Petroleum Exploration and Development
Shuang Li China University of Petroleum - Beijing
Junlin Yi China University of Petroleum - Beijing
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Published Date

2023

Language

English

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Abstract

The fractures are the main flow and heat transfer channel for fluids in deep high-temperature enhanced geothermal systems (EGS). The deformation of the fracture controlled by reactive flow is a common phenomenon during geothermal development, which might lead to a reduction in the system's thermal performance and operating life. While most previous research focuses on the influence of fracture deformation on system heat extraction performance, conversely the fracture deformation mechanism caused by the reactive flow is ignored. In this paper, a coupled thermal-hydraulic-chemical-deformation (THCD) model is established to investigate the fracture deformation mechanism. The deformation behavior of quartz and anorthite is compared, and the Damkohler number (Da) is adopted to explore the reaction mechanism. Meanwhile, the influence mechanism of concentration and temperature on fracture deformation is also analyzed. Results show that the Da at the fracture surface is 10−12 -10−8, which means that the deformation of the fracture is controlled by the reaction rate. Compared with the concentration, the influence of temperature on fracture deformation is complex, and there is an inflection point. The inflection point is governed by the mineral reaction kinetics. These results provide significant references for the efficient heat extraction of the EGS.