UQ-CCSGCentre for Coal Seam Gas
This research seeks to understand the gas flow behaviours incleats, and the main objectives are:β’ To build a LBM model to simulate bubble-water dynamics
at pore scale;β’ To analyse the effects of wettability and capillary pressure
on gas-water flow capacity.
Fig. 1 Schematic diagram of the distribution and force analysis of gas bubble and gas column in capillary tubes (Xiangfang Li et al., 2012).
The gas/water two-phase flow in cleat networks has been acritical issue in coal seam gas (CSG) reservoirs. A keyparameter affecting the flow of gas in coal cleats is the wettingpotential of gas/water (Li et al., 2012; Zhang et al., 2015).However, our understanding of wettability effects on gas flowstill needs further research.
Background
Main objectives
Fig. 2 Schematic diagram of (a) contact angle and (b)capillary imbibition phenomenon (http://www.reservoirengineering.org.uk)
(a) (b)High
wettabilityLow wettability
Jie Yi, Centre for Geoscience Computing, School of Earth Sciences, UQSupervisors: Associate Professor Huilin Xing, Professor Victor Rudolph
Lattice Boltzmann equations
20 kinds of point
To distinguish different points on the fluid/solid interaction
ππππ ππ + πππππΏπΏπΏπΏ, πΏπΏ + πΏπΏπΏπΏ = ππππ ππ, πΏπΏ + 1 β ππ ππππ ππ + πππππΏπΏπΏπΏ, πΏπΏ β ππππ ππ, πΏπΏ + ππππππππ ππ, πΏπΏ β ππππ ππ, πΏπΏ
ππππ
ππππ ππ + πππππΏπΏπΏπΏ, πΏπΏ + πΏπΏπΏπΏ
= ππππ ππ, πΏπΏ + ππππππππ ππ, πΏπΏ β ππππ ππ, πΏπΏ
ππππ+ 1 β 1
2πππππππππππ π 2
ππππ β ππ + ππππ β πππππ π 2
ππππ β πππππ»π»ππ + ππππ πΏπΏπΏπΏ
ππ πΈπΈππ = 5,ππ = 0.2267 ππ πΈπΈππ = 10,ππ = 0.453 ππ πΈπΈππ = 20,ππ = 0.907
Fig. 5 Bubble shapes under different buoyancy force. This model (top) Naoki Takada model (bottom).
Fig. 3 The verification of the wetting boundary condition
Fig. 4 The verification of the Laplace law
Fig. 6 Dynamic behaviour of bubble-water flow in a single cleat with different contact angles: (a) 68Β°, (b) 90Β°, (c) 112Β°
Fig. 7 (a) Schematic illustration of simulation geometry (the red, blue and white are water, gas and solid, respectively); (b) Evolution of
average velocity of bubble with different drag forces
β’ For different contact angles, the gas bubble shape andmovement are significantly different, which means therelative permeability highly depends on wettability of coal.
β’ For bubble-water flowing in a cleat with a narrow throat, thecapillary pressure plays an important role in determining thefluid flow capacity.
β’ These phenomena are likely to have significant impacts ondrainage rates and relative permeability within a coal seam.
Simulation results
Conclusions
The author appreciates the funding provided by the UQ Centre for Coal SeamGas (CCSG) and its industry members APLNG, Arrow Energy, QGC & Santos.
1. Background and research objectives
2. Wettability
5. Simulation results and conclusions
4. Benchmark
Acknowledgements
3. Methodology
CCSG A1 Posters 2016.indd 14 11/08/2016 4:47 PM
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