Browsing by Author "Chen, Hung-Hui"

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Effect of connectivity and wettability on the relative permeability of NAPLs
(2009-02-01)
Chang, Liang-Cheng
;
Chen, Hung-Hui
;
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.
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
;
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.