Experimental Study On Multi-phase Flow Of Air, Water And LNAPL In Porous Media Based On 2-D Porous Media Network Model

The rapidly development of the petroleum industry as well as the widely use of petroleum products has kept the pace for decades. Some accidental leakage and spillage of these oil-oriented products namely Light Non-Aqueous Phase Liquids (LNAPL) happens from time to time and lead to soil and groundwater contamination. These problems are of great concern. Study on soil remediation and clean techniques have been widely carried on. However, an effective soil remediation measures can be successfully implemented only when the multi-phase flow behavior in microscopic porous media is concluded.The purpose of this study is to simulate the multi-phase flow distribution and migration behavior in porous media. Air, distilled water and n-hexadecane constitute the designated multi-phase flow while n-hexadecane was selected as a representative LNAPL. A 2-D micro-model namely network model was used to represent the porous media. By using network model and Visualization techniques, multi-phase in the micro structure can be clearly observed. Phase trap, snap-off and multi phase migration can be clearly identified. The multi phase transportation principle can therefore be analyzed and then clarified. This research could be concluded as follow:1. Development of the 2-D micro porous network modelQuartz sand was select as a representative porous media, the structure was studied and the feature was used to design the micro model. Glass was selected as the hydrophilic material while PDMS was selected as a hydrophobic one. Micro models of different coordination number and different material were then developed. These models were later used as porous media models in discussing multi-phase flow behavior in porous media.2. Visualization approach in micro-model analyzing techniqueA visualization setup including a stereo microscope, Moticam? system, and a computer as well as the accessory was used to acquire the image and analyze the test result. The visualized test result will provide direct support to analyze multi-phase flow behavior in porous media. The experiment afterward was done using this approach. 3. Multiphase distribution mechanics in micro porous structureMulti-phase flow behavior in porous media was first introduced through detailed mechanic discussions. A batch of experiments was then carried out to verify the discussion result. The major factors influence the phase distribution in porous media in the designated test condition are 1) coordination number of the porous structure, 2) wetting characteristic of the phase and the flowing channel, and 3) distribution of interfacial tension at the phase interface.4. Multiphase migration principle in micro porous structurePhase saturation and phase conductivity in porous structure was discussed and the determination approach was clarified. A batch of experiments was then carried out so as to further the discussion. The phase residue saturation was directed determined by coordination number of the porous structure. LNAPL snap-off happens only when the coordination is greater than 2. The function of the phase saturation and the function of conductivity are negative correlated.