Open Access
ARTICLE
A Numerical Gas Fracturing Model of Coupled Thermal, Flowing and Mechanical Effects
Dan Ma1, 2, Hongyu Duan2, Qi Zhang3, *, Jixiong Zhang1, Wenxuan Li2, Zilong Zhou2, Weitao Liu4
1 State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China University of Mining &
Technology, Xuzhou, 221116, China.
2 School of Resources & Safety Engineering, Central South University, Changsha, 410083, China.
3 Beijing Research Institute of Uranium Geology, Beijing, 100029, China.
4 State Key Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and
Technology, Qingdao, 266590, China.
* Corresponding Author: Qi Zhang. Email: .
Computers, Materials & Continua 2020, 65(3), 2123-2141. https://doi.org/10.32604/cmc.2020.011430
Received 08 May 2020; Accepted 26 June 2020; Issue published 16 September 2020
Abstract
Gas fracturing, which overcomes the limitation of hydraulic fracturing, is a
potential alternative technology for the development of unconventional gas and oil
resources. However, the mechanical principle of gas fracturing has not been learned
comprehensively when the fluid is injected into the borehole. In this paper, a damagebased model of coupled thermal-flowing-mechanical effects was adopted to illustrate the
mechanical principle of gas fracturing. Numerical simulation tools Comsol Multiphysics
and Matlab were integrated to simulate the coupled process during the gas fracturing.
Besides, the damage evolution of drilling areas under several conditions was fully
analyzed. Simulation results indicate that the maximum tensile stress, which occurs in the
upper and lower of the injection hole, decreases with the increase of the tectonic stress
coefficient (TSC). As the TSC increases, shear fractures increase, a crushed area is
gradually formed and the seepage area increases rapidly. The influence of TSC on
fracture expansion is concluded as follows: with the decrease of TSC, the relative width
of fractures decreases whilst the depth increases. It indicates that thermal stress and pore
pressure promote the expansion of tensile fractures but restrain the expansion of shear
fractures. Therefore, a relatively lower injection gas pressure is required to obtain the
same degree of fracturing with a coupled thermal gradient.
Keywords
Cite This Article
D. Ma, H. Duan, Q. Zhang, J. Zhang, W. Li
et al., "A numerical gas fracturing model of coupled thermal, flowing and mechanical effects,"
Computers, Materials & Continua, vol. 65, no.3, pp. 2123–2141, 2020.
Citations