Browsing by Author "Shan, Hsin-Yu"

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Effect of connectivity and wettability on the relative permeability of NAPLs
(2009-02-01)
Chang, Liang-Cheng
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Chen, Hung-Hui
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Shan, Hsin-Yu
;
Tsai, Jui-Pin
;
土木工程學系
The characteristic relationships among relative permeability (K(r)), saturation (S) and capillary pressure (P) of NAPLs are the important constitutive laws to simulate the NAPLs flow in the subsurface. In this study, a micro model was used to obtain the values of permeability, saturation for the multi-phase flow of five fluid-pairs. The perspective micro model allows one to clearly observe the multiphase flow and allow this study to precisely measure the fluid saturation by digital image analysis. The experimental results showed hysteresis phenomenon of relative permeability versus saturation and that was not interpreted by previous studies. By carefully examining the recorded images, this study found that the degree of the connectivity for the micro channel occupied by wetting phase fluid could influence the relative permeability. Therefore, for the same saturation, the relative permeability in the imbibition is higher than that in the drainage. The results of the K(r)-S experiments for five fluid-pairs also showed that the residual saturation of wetting phase fluid decreased with the wettability increasing but increased with the interfacial tension increasing. Those interpretations and experimental results are valuable references for groundwater remediation and oil reservoir development.
Effects of liquid layers and distribution patterns on three-phase saturation and relative permeability relationships: a micromodel study
(2017-12-01)
Tsai, Jui-Pin
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Chang, Liang-Cheng
;
Hsu, Shao-Yiu
;
Shan, Hsin-Yu
;
土木工程學系
In the current study, we used micromodel experiments to study three-phase fluid flow in porous media. In contrast to previous studies, we simultaneously observed and measured pore-scale fluid behavior and three-phase constitutive relationships with digital image acquisition/analysis, fluid pressure control, and permeability assays. Our results showed that the fluid layers significantly influenced pore-scale, three-phase fluid displacement as well as water relative permeability. At low water saturation, water relative permeability not only depended on water saturation but also on the distributions of air and diesel. The results also indicate that the relative permeability-saturation model proposed by Parker et al. (1987) could not completely describe the experimental data from our three-phase flow experiments because these models ignore the effects of phase distribution. A simple bundle-of-tubes model shows that the water relative permeability was proportional to the number of apparently continuous water paths before the critical stage in which no apparently continuous water flow path could be found. Our findings constitute additional information about the essential constitutive relationships involved in both the understanding and the modeling of three-phase flows in porous media.
Experimental study on imbibition displacement mechanisms of two-phase fluid using micro model
(2009-12-01)
Chang, Liang-Cheng
;
Tsai, Jui-Pin
;
Shan, Hsin-Yu
;
Chen, Hung-Hui
;
土木工程學系
This study applies a transparent micro model and digital image analysis to the experimental study of the displacement mechanisms for water and air in porous media during imbibition process, and examines the displacement formulas. This study conducts experiments following Lenormand's assumptions as closely as possible. Various displacement mechanisms were observed, and their images were recorded. The displacement mechanisms in imbibition are mainly snap-off, In type imbibition and piston-type motion. The experimental fluid displacement images and associated capillary pressure were then used to verify the displacement formulas. This experimental study shows that, when snap-off occurred, the experimental capillary pressures were close to the Lenormand's estimation of critical capillary pressures where enough surrounding area of the throat was saturated. When I1 and I2 type imbibitions occurred, the experimental capillary pressures were also close to the Lenormand's estimation of critical capillary pressures where enough connecting throats were saturated. The In type imbibition and its associated piston-type motions are the main processes to increase the wetting phase fluid saturation. For the pore-throat distribution applied in this study, snap-off can facilitate the occurrence of In type imbibition and its associated piston-type motion; therefore, snap-off is an important displacement mechanism in facilitating the increase of the wetting phase fluid saturation in the imbibition process. To summarize, this study provides valuable experimental support and suggestions for Lenormand's displacement formulas, which are the basis for many related experimental and numerical studies.
Joint Impact of Scaling and Hysteresis on NAPL Flow Simulation
(2009-12-01)
Chen, Hung-Hui
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Chang, Liang-Cheng
;
Shan, Hsin-Yu
;
Tsai, Jui-Pin
;
土木工程學系
The hysteresis of capillary pressure versus saturation (P-S) relation is an important constitutive relation in multiphase flow, since the P-S relation is widely used to predict P-S relations in the simulation of the non-aqueous phase liquids (NAPLs). This work examined the performance of the scaling rule on predicting the P-S relationship and then studied the joint impact of the scaling and hysteresis on the multiphase NAPL flow simulation. Various experimental P-S values of distinct fluid pairs were compared with the scaled P-S curves using the scaling rule. The comparison indicated that the prediction of P-S is more accurate when the water-air P-S curve is used to scale other P-S curves. The joint impact of the scaling and hysteresis on the NAPLs flow simulation was then investigated by numerical simulation studies. The NAPL simulator was used to simulate the outcome of several scenarios based on a system with water-NAPL-air in a hypothetical sand tank. For both gasoline and trichloroethylene, the difference of the injected NAPL volume between no hysteretic and hysteretic simulations over a given time period was the smallest when the water-air P-S curve was used to scale other P-S curves. Simulation results of this study are valuable references for predicting the distribution of NAPLs.
The application of system dynamics to water resources sustainable use for the Kaopin river basin
(2005)
Yang, Chao-Chung
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Shan, Hsin-Yu
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Lee, Han-Keng
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Hsu, Shao-hua
;
Chen, Tze-Wei
The demand for water in Kaopin river basin has increased significantly in recent years owing to industrial growth and increasing living standards. This situation not only raises the crisis of water deficit but also brings serious problem of water pollution. Hence, any suitable strategy is required to consider simultaneously the effect between water quantity and water quality. A system dynamics model is including the critical feedback structures in the system. Simulating the model shows the effect of the system structure on policy interventions. Therefore, system dynamics is well-suited to analyzing problems whose behavior is governed by feedback relationships and which have a long-term time horizon. Finally, this study addressed two major problems: 1) water deficit, 2) water pollution and then makes the appropriate strategy to avoid the huge impact between water deficit and water pollution and also prohibit the time delay of strategy.