Micro-scale simulation of bubble-water flow in coal seams by the lattice Boltzmann method
Jie Yi A , Huilin Xing A , Tianwei Sun B and Victor Rudolph AA Centre for Geoscience Computing, School of Earth Sciences, The University of Queensland.
B Leading Petro-tech Co., Ltd.
The APPEA Journal 56(2) 608-608 https://doi.org/10.1071/AJ15114
Published: 2016
Abstract
The production of coal seam gas initially requires pumping and removing significant amounts of water to sufficiently reduce the hydrostatic pressure in the subsurface, so that methane can desorb from the matrix and diffuse into the cleat systems; majority of the methane molecules gather into nucleation or bubbles. During the depression, the flow pattern of gas in cleats changes from bubble flow to slug flow, and finally forms circular flow. The significance of the bubble flow process—during which the liquid phase is continuous while the gas phase exists as small bubbles randomly distributed within the liquid—has not been emphasised because of its complexity.
In this study, a free energy based two-phase lattice Boltzmann model is used to simulate the gas bubble/water flow behaviour in micro-cleats of a coal seam gas reservoir. The model was validated by comparison with analytical results based on dimensionless numbers, and good agreement was found in general. The influences of bubble shape, bubble size, and coal surface wettability on gas water two-phase flow in micro-cleats are discussed.
The simulation results indicate that the bubble size and wettability of gas have significant impacts on the flow capacity of both gas and water. A decrease of the water flow rate is observed when large bubbles occur, and the gas flow rate decreases when the gas wettability becomes stronger. The bubble flow process significantly influences the drainage of water and the further gas production.
Jie Yi is a PhD candidate at the School of Earth Sciences at the University of Queensland, researching multiphase flow dynamics at the pore scale using the Lattice Boltzmann method. She has a MSc (petroleum engineering) from China University of Petroleum and a BE (petroleum engineering) from China University of Geosciences. Her research interests include modern gas well tests and multiphase flow. |
Huilin Xing is Deputy Director and Principal Research Fellow of the Centre for Geoscience Computing at the University of Queensland. He received his PhD in computational mechanics and engineering in 1995 at Harbin Institute of Technology (China), and then worked at the Institute of Physical and Chemical Research (RIKEN) in Japan for Earth Simulator before coming to UQ in 2002. He has been working on advanced computational model and software development for simulating large-scale non-linear multi-physical (thermo-hydro-mechanical-chemical) coupled geo-science and engineering issues across different scales spanning from pore to lab and field scales. |
Tianwei Sun is a senior research engineer in Leading Petro-Tech Company, China, that focuses on the research of borehole reservoir geophysics. Previously, he worked with Schlumberger as a Production Stimulation Engineer for two years. Sun’s research interest includes hydraulic fracturing, microseismic monitoring, and reservoir modeling in unconventional resources. He holds BS degrees double major in petroleum engineering and mathematics from University of Tulsa , US. |
Victor Rudolph received his PhD from the University of Natal in 1985. He is Head of the ENtri research group, which combines the expertise ofUQ’s environmental engineering and chemical engineering divisions in its focus on energy environment engineering. His present research projects are in the fields of gasification of coal in a compartmented fluid bed reactor, mixing and circulation in a fluid bed with a draft tube, liquid and gas, flow near the raceway in a blast furnace, fundamental standpipe studies, etc. |
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