Simulations on the micro-seepage rules of gas and water based on micro-CT/CFD and the related contrastive analysis
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ORIGINAL PAPER
Simulations on the micro-seepage rules of gas and water based on micro-CT/CFD and the related contrastive analysis Lei Qiu 1,2 & Gang Zhou 1,2 & Wenzheng Zhang 1,2 & Weibo Han 1,2 Received: 29 March 2018 / Accepted: 8 August 2019 # Saudi Society for Geosciences 2019
Abstract This study first employed micro-computed tomography technique for scanning the gas-fat coal sample; then, using Avizo software, coal’s micro-pore structure model was established; finally, seepage behaviors of gas and water in the coal under a pressure of 3 MPa were simulated. Through comparison, it can be concluded that both gas pressure and water pressure decreased gradually along the seepage direction; at a same seepage length, water’s maximum seepage pressure significantly exceeded that of gas; gas’s velocity flow lines were overall fuller than water’s flow lines; using a same pore model, gas’s migration velocity far exceeded that of water; In terms of mass flow rate, water exceeded gas. The effluent mass flow rate at the outlet was smaller than the influent mass flow rate at the inlet. Overall, with the increase in the seepage length, gas and water’s mean seepage pressures and mass flow rates all decreased gradually, while their mean seepage velocities fluctuated greatly. Since the pores at the different coal cross-sections were developed to different degrees, the heterogeneity of the coal structure meant that the cross-sectional area of the pore channel varied irregularly along the seepage direction. The fitting curve can be reduced to three classes: logistic linear regression curve, Boltzmann function curve, Exp Dec curve, or poly curve. Keywords Micro-CT . Digital core . Micro-pore model . Optimal segmentation threshold . Comparison of seepage behaviors between gas and water Flammable and combustible coal-mine gas can very easily lead to accidents in coal mines, which can cause a large number of injuries and fatalities (Aguado and Nicieza 2007; Sheng et al. 2013; Zhang et al. 2018; Zhou et al. 2017); furthermore, it is generally recognized as the main cause of death in coal mines. Coal and gas outbursts have always been the main type of accident in China’s mines, while the law of gas seepage is an important factor that affects coal and gas outbursts (Fan et al. 2018; Li 2010; Wold et al. 2008; Zhou et al. 2018b). In the past few decades, many academics have conducted a great deal of Editorial handling: F. Dai * Gang Zhou [email protected] 1
College of Mining and Safety Engineering, Shandong University of Science and Technology, Qingdao 266590, China
2
State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China
research on the occurrence mechanism of coal and gas outbursts’ several aspects including theory, experiments, and numerical simulations and have achieved insightful results. In terms of theoretical research, Litwiniszyn (1985); Meng et al. (1996); Zhou et al. 2
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