Quantifying Fracture Dynamics in Clean Energy: A Novel Fractal Perspective

¹ State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
² Mechanics and Civil Engineering Institute, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
³ WA School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, Kalgoorlie, WA 6430, Australia

^* Corresponding author: theoye@cumt.edu.cn

Abstract

Geothermal energy, as an emergent source of power, has consistently been a focal point of scholarly investigation both domestically and internationally, with a particular emphasis on the prediction and assessment of its extraction efficiency. In common geothermal extraction projects, the seepage behavior of water within the fractures for the geothermal reservoirs significantly impacts the efficiency of resource extraction. This study introduces an interdisciplinary fractal model for geothermal extraction. An enhanced fractal theory, tailored for geothermal reservoirs, is proposed, employing four innovative fractal parameters— fracture fractal dimension, fracture tortuosity fractal dimension, fracture roughness parameter, and maximum fracture length—to quantitatively characterize the fracture structure. This refined fractal theory is applied to geothermal reservoir extraction under the complex thermal-hydromechanical coupling. The findings indicate that the proposed structural parameters effectively characterize the micro-macro interactions during the geothermal extraction process. Significant evolution of these fractal parameters is observed throughout the extraction process. Furthermore, there is an inverse relationship between geothermal extraction efficiency and two key fractal parameters—fracture tortuosity fractal dimension and fracture roughness parameter—while the reservoir stress is directly proportional to these parameters.