Dual-scale insights of two-phase flow in inter-cleats based on microfluidics: Interface jumps and energy dissipation

Abstract

Cleat serves as the primary flow pathway for coalbed methane (CBM) and water. However, few studies consider the impact of local contact on two-phase flow within cleats. A visual generalized model of endogenous cleats was constructed based on microfluidics. A microscopic and mesoscopic observation technique was proposed to simultaneously capture gas-liquid interface morphology of pores and throat and the two-phase flow characteristics in entire cleat system. The local contact characteristics of cleats reduced absolute permeability, which resulted in a sharp increase in the starting pressure. The reduced gas flow capacity narrowed the co-infiltration area and decreased water saturation at the isotonic point in a hydrophilic environment. The increased local contact area of cleats weakened gas phase flow capacity and narrowed the co-infiltration area. Jumping events occurred in methane-water flow due to altered porosity caused by local contact in cleats. The distribution of residual phases changed the jumping direction on the micro-scale as well as the dominant channel on the mesoscale. Besides, jumping events caused additional energy dissipation, which was ignored in traditional two-phase flow models. This might contribute to the overestimation of relative permeability. The work provides new methods and insights for investigating unsaturated flow in complex porous media.

Keywords

Inter-cleat / Microfluidics / Two-phase flow / Dual-scale / Interface jump / Inertial effect

Acknowledgements

The authors are grateful for the financial support from the National Natural Science Foundation of China (No. 42102127) and the Postdoctoral Research Foundation of China (No. 2024 M751860).

References

[1] Zhang XM, Chen BYY, Zheng ZZ, Feng QH, Fan B. New methods of coalbed methane production analysis based on the generalized gamma distribution and field applications. Appl Energy 2023;350:121729.

[2] Zhang R, Cheng YP, Yuan L, Zhou HX, Wang L, Zhao W. Enhancement of gas drainage efficiency in a special thick coal seam through hydraulic flushing. Int J Rock Mech Min Sci 2019;124:104085.

[3] Xue Y, Ranjith PG, Gao F, Zhang ZZ, Wang SH. Experimental investigations on effects of gas pressure on mechanical behaviors and failure characteristic of coals. J Rock Mech Geotech Eng 2023; 15(2):412-28.

[4] Li R, Wang SW, Lyu SF, Xiao YH, Su DM, Wang JC. Dynamic behaviours of reservoir pressure during coalbed methane production in the southern Qinshui Basin. North China Eng Geol 2018;238:76-85.

[5] Sun FR, Liu DM, Cai YD, Qiu YK. A micro-macro coupled permeability model for gas transport in coalbed methane reservoirs. Energy 2023;284:128604.

[6] Xiao ZY, Wang G, Wang CS, Jiang YJ, Jiang F, Zheng CC. Permeability evolution and gas flow in wet coal under non-equilibrium state: Considering both water swelling and process-based gas swelling. Int J Min Sci Technol 2023; 33 (5):585-99.

[7] Li H, Liu W, Lu J, Lu Y, Shi S, Wang Z, Ye Q, Jia Z. Effect of microwave-assisted acidification on the microstructure of coal: XRD, 1H-NMR, and SEM studies. Int J Min Sci Techno 2023; 33(7):919-26.

[8] Song WH, Yao J, Ma JS, Sun H, Li Y, Yang YF, Zhang L. Numerical simulation of multiphase flow in nanoporous organic matter with application to coal and gas shale systems. Water Resour Res 2018; 54(2):1077-92.

[9] Jeong GS, Lee J, Ki S, Huh DG, Park CH. Effects of viscosity ratio, interfacial tension and flow rate on hysteric relative permeability of CO₂/brine systems. Energy 2017;133:62-9.

[10] Goodarzian S, Sorbie KS. Correct relative permeability data from steady-state experiments for capillary end effects. Geoenergy Sci Eng 2023;224:211626.

[11] Hemmati N, Borazjani S, Yang S, Badalyan A, Genolet L, Behr A, Zeinijahromi A, Bedrikovetsky P. Laboratory validation of steady-state-transient test to determine relative permeability and capillary pressure. Fuel 2022;321:123940.

[12] Zhou X, Sheng JL, Ye ZY, Yang XL. Two-phase flow visualization experiments in variable-aperture fractures: The correlation between flow structure, displacement efficiency and relative permeability. Int J Rock Mech Min Sci 2024;176:105693.

[13] Shen J, Qin Y, Wang GX, Fu XH, Wei CT, Lei B. Relative permeabilities of gas and water for different rank coals. Int J Coal Geol 2011; 86(2-3):266-75.

[14] Zhang JZ, Gao SS, Xiong W, Ye LY, Liu HX, Zhu WQ, An WG, Han DH, Lin BC. A New model of gas-water two-phase seepage based on Newton’s law of motion. Heliyon 2024; 10(20):e39179.

[15] Sun XX, Yao YB, Ripepi N, Liu DM. A novel method for gas-water relative permeability measurement of coal using NMR relaxation. Transp Porous Medium 2018; 124(1):73-90.

[16] Yang YF, Sun W, Sun H, Zhang L, Zhong JJ, Zhang KQ, Yao J. Pore scale characterization of gas-water flow in heterogeneous layered sandstone. Energy & Fuels 2013.

[17] Zhao YX, Wu Y, Han SB, Xue SB, Fan GW, Chen ZW, Elabd A. Water sorptivity of unsaturated fractured sandstone: Fractal modeling and neutron radiography experiment. Adv Water Resour 2019;130:172-83.

[18] Yang S, Li HX, Suo S, Wu Z. Viscous-dependent fingering dynamics of gas invading into multi-fluids. Adv Water Resour 2024;191:104757.

[19] Wang CG, Zhang JD, Zang YX, Zhong RZ, Wang JG, Wu Y, Jiang YJ, Chen ZW. Time-dependent coal permeability: Impact of gas transport from coal cleats to matrices. J Nat Gas Sci Eng 2021;88:103806.

[20] Du YJ, Mehmani A, Xu K, Kelly S, Balhoff M, Torres-Verdín C. Microfluidic diagnostics of the impact of local microfracture connectivity on hydrocarbon recovery following water injection. Water Resour Res 2020; 56(7): e2019WR026944.

[21] Eliebid M, Mohamed A, Arshadi M, Gong YB, Piri M. Steady-state relative permeability measurements in rough-walled fractures: The effects of wettability and aperture. Chem Eng Sci 2024;298:120402.

[22] Zhang H, Papadikis K, Shaw SJ. A two-dimensional study on the impact of pore space connectivity on the immiscible two-phase flow in a water-wet, water-oil system under steady state conditions. Int J Multiph Flow 2022;150:104026.

[23] Su XB, Yao S, Song JX, Wang Q, Li F. The discovery and control of slug flow in coalbed methane reservoir. J Petrol Sci Eng 2019;172:115-23.

[24] Chen YF, Fang S, Wu DS, Hu R. Visualizing and quantifying the crossover from capillary fingering to viscous fingering in a rough fracture. Water Resour Res 2017; 53(9):7756-72.

[25] Zhang Z, Qin Y, Fu XH, Yang ZB, Guo C. Multi-layer superposed coalbed methane system in southern Qinshui Basin, Shanxi Province. China J Earth Sci 2015; 26(3):391-8.

[26] Jia L, Li KW, Shi XH, Zhao LP, Linghu JS. Application of gas wettability alteration to improve methane drainage performance: A case study. Int J Min Sci Technol 2021; 31(4):621-9.

[27] Zhang YB, Li QG, Hu QT, Zhai C, Song MY, Xu JZ, Deng YZ, Liu P, Sun Y, Shi JL, Hu LP. Pore wetting process characterization of Equal-Sized granular coals by using LF-NMR technology. Fuel 2022;313:122670.

[28] Lyu SF, Chen XJ, Shah SM, Wu XM. Experimental study of influence of natural surfactant soybean phospholipid on wettability of high-rank coal. Fuel 2019;239:1-12.

[29] Han W. Occurrence and production mechanism of coal fines in coalbed methane wells of Shizhuang Block, Qinshui Basin. China University of Mining and Technology; 2021. Doctoral dissertation.

[30] Qin XJ, Cai JC, Wang G. Pore-scale modeling of pore structure properties and wettability effect on permeability of low-rank coal. Int J Min Sci Technol 2023; 33(5):573-84.

[31] Yan FZ, Zeng T, Yang MM, Peng SJ, Gao CJ, Yang YD. Study on pore-crack evolution and connectivity of coal subjected to controlled electrical pulse based on CT scanning technology. Energy 2024;296:131200.

[32] Wang YX, Al Shakhshir S, Li XG. Development and impact of sandwich wettability structure for gas distribution media on PEM fuel cell performance. Appl Energy 2011; 88(6):2168-75.

[33] Zhang YB, Zhang BY, Yang SQ, Zhong ZG, Zhou HP, Luo XP. Enhancing the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect with sodium dodecyl sulfate surfactant. Int J Min Sci Technol 2021; 31 (6):995-1002.

[34] Haines W. The hysteresis effect in capillary properties and the mode of moisture distribution associated therewith. J Agric Science 1929;20:1-7.

[35] Moebius F, Or D. Interfacial jumps and pressure bursts during fluid displacement in interacting irregular capillaries. J Colloid Interface Sci 2012; 377(1):406-15.

[36] Zhang JC, Chen SJ, Ji ST, Feng F, Aleksey AK, Zaki MM. Imaging dynamic water invasion behavior in microfractures based on microfluidics. J Cent South Univ 2022; 29(12):3986-4001.

[37] Sun ZH, Carlos SJ. Haines jumps: Pore scale mechanisms. Phys Rev E 2019; 100 (2-1):023115.

[38] Ferrari A, Lunati I. Inertial effects during irreversible meniscus reconfiguration in angular pores. Adv Water Resour 2014;74:1-13.

[39] Moebius F, Or D. Inertial forces affect fluid front displacement dynamics in a pore-throat network model. Phys Rev E 2014; 90(2):023019.

[40] Morrow NR. Physics and thermodynamics of capillary action in porous media. Ind Eng Chem 1970; 62(6):32-56.

[41] Zhang Z, Yan DT, Yang SG, Zhuang XG, Li GQ, Wang G, Wang XM. Experimental studies on the movable-water saturations of different-scale pores and relative permeability of low-medium rank coals from the Southern Junggar Basin. J Nat Gas Sci Eng 2020;83:103585.

[42] Zhang XY, Wu CF, Liu SX. Characteristic analysis and fractal model of the gaswater relative permeability of coal under different confining pressures. J Petrol Sci Eng 2017;159:488-96.

[43] Zhang JY, Feng QH, Zhang XM, Wen SM, Zhai YY. Relative permeability of coal: A review. Transp Porous Medium 2015; 106(3):563-94.

[44] Chen SJ, Zhang JC, Yin DW, Cheng XZ, Jiang N. Relative permeability measurement of coal microchannels using advanced microchip technology. Fuel 2022;312:122633.

[45] Beltrán A, Hernández-Díaz D, Chávez O, García A, Mena B, Zenit R. Experimental study of the effect of wettability on the relative permeability for air-water flow through porous media. Int J Multiph Flow 2019;120:103091.