archives@tulane.edu / Enhanced oil recovery (EOR) and oil spill remediation (OSR) in porous media both share a common theme in that they can both be modeled as a system comprising of two immiscible liquid phases and a solid porous phase. EOR seeks to improve the recovery of crude oil from existing oil reserves, while OSR improves ecological sustainability. In this thesis two novel techniques with the potential of improving the recovery of non-aqueous phase liquid (NAPL) that is trapped in a water filled random porous media. In the first project, an oil-soluble surfactant was studied to enhance crude oil mobilization in a cryolite-packed miniature bed. The cryolite packed bed provided a transparent, random porous medium for observation at the microscopic level. In the first part of the project, oil-soluble surfactants; Span 80 and Eni-surfactant (ES) were dissolved directly into the crude oil. The porous medium was imbued with the crude oil (containing the surfactants), and deionized water was the flooding phase, in this experiment, the system containing ES had the best performance. Subsequently, Sodium Dodecyl Sulfate (SDS), a hydrosoluble surfactant was used to solubilize the ES, with the SDS acting as a carrier for the ES to the contaminated porous media. Finally, the SDS/Eni-Surfactant micellar solutions were used in oil-removal tests on the packed bed. Grayscale image analysis was used to quantify the oil recovery effectiveness for the flooding experiments by measuring the white pixel percentage in the packed bed images. The SDS/ES flooding mixture had a better performance than the SDS alone. Furthermore, a model liquid hydrocarbon (n-hexadecane) was used to gain insight on the mobilization of non-aqueous phase liquids (NAPLs) trapped in porous formations, important for both EOR and oil spill remediation in porous media. Food-grade surfactants lecithin from soy and tween 80 were compared to commercial dispersant Corexit 9500A, for their ability to mobilize the hydrocarbon originally trapped in a water-filled cryolite porous medium. Red dye was added to the n-Hexadecane to improve visualization, and the aqueous phase incorporated different ratios of the surfactants Lecithin and Tween 80 to seek synergistic benefits when the two surfactants are combined. Visual-microscopic flooding experiments carried on a miniature packed bed produced images which were then analyzed using grayscale image analysis. It was determined that a ratio 40:60 by weight of Lecithin to Tween 80 has the best performance in the mobilization of n-hexadecane from the porous media. Furthermore, any (non-optimal) mixture of lecithin and tween 80 exhibited a better (synergistic) performance in n-Hexadecane recovery from the porous media than when applying either surfactant separately. Finally, applying the video-microcapillary technique utilized in the first two projects, but with a slight modification, the effect of temperature change on a highly viscous oil phase flowing through a water-filled porous media was studied. The glass microcapillary was coated externally with a thin film of Indium Tin Oxide (ITO) to render it electrically conductive. When an electric current is applied to the outside of the coated capillary, the temperature of the capillary can be elevated. The tapered region of the capillary is filled with cryolite to form a random porous media and flow experiments were conducted in this region. Applying this technique, we studied the flow pattern of a highly viscous oil displacing an aqueous phase in a porous media at 60, 70, 80, 90, and 100oC. Also, we observed capillary fingering, continuous, and Haines jump flow patterns, with capillary fingering and Haines jump more prominent at 10-3 capillary number, while flow at 10-2 exhibited continuous flow pattern. Chapters 2 and 3 of this dissertation include content in peer-reviewed journal articles published by the author.1,2 / 1 / Chike George Ezeh

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Wave interaction with a rubble-mound breakwater has been studied experimentally in the thesis. The breakwater may contain multi-layer anisotropic but homogeneous media. Fluid outside the porous layer field is assumed to incompressible and viscous,and the flow field is irrational. The study applies the velocity potential to describe the wave field with small amplitude incident wave. Under the consideration of linearity, Analytical solution is solved from boundary value program by the method of separation of variables. It bases on dispersion equation. Try to find the range and position of the complex eigenvalues in each porous column and to solve the velocity potential in the field by numerical methods. Wave reflection, transmission, and energy dissipation with a rubble-mound breakwater have been investigated experimentally, and consider the wave close linear wave theory, the wave steepness smaller than 0.035. Three different sizes of grain are used to construct the porous base, they are 16mm, 25mm, and 35mm, respectively. Single and double layers of porous base are considered. Some of the reflection coefficient are convergence, but they are the unreasonable results. Maybe the trouble is in the process of the computation with determination of .eigenvalues. When the wave has long period, the double-layer porous model reduces more wave energy, when the wave has short period, the single-layer porous and the smaller porous material model can disappears more wave energy. The characteristic of internal resistance in the porous has the difference along with the wave period. When the model crest is higher than the sea level, the consumption of wave energy are more when it is shorter along with the wave period. As a submerged breakwater, the effect for disappears wave energy to be limited.

There have been significant advances in the research of nanoparticle technologies for formation evaluation and reservoir engineering operations. The target applications require a variety of different retention characteristics ranging from nanoparticles that adsorb near the wellbore to nanoparticles that can travel significant distances within the porous medium with little or no retention on the grain substrate. A detailed understanding of the underlying mechanisms that cause nanoparticle retention is necessary to design these applications. In this thesis, experiments were conducted to quantify nanoparticle retention in unconsolidated columns packed with crushed Boise sandstone and kaolinite clay. Experimental parameters such as flow rate, injected concentration and sandpack composition were varied in a controlled fashion to test hypotheses concerning retention mechanisms and enable development and validation of a mathematical model of nanoparticle transport. Results indicate nanoparticle retention, defined as the concentration of nanoparticles remaining attached to grains in the porous medium after a volume of nanoparticle dispersion is injected through the medium and then displaced with brine, is a function of injected fluid velocity with higher injected velocities leading to lower retention. In many cases nanoparticle retention increased nonlinearly with increasing concentration of nanoparticles in the injected dispersion. Nanoparticle retention concentration was found to exhibit an upper bound beyond which no further adsorption from the nanoparticle dispersion to the grain substrate occurred. Kaolinite clay was shown to exhibit lower retention concentration [mg/m2] than Boise sandstone suggesting DLVO interactions do not significantly influence nanoparticle retention in high salinity dynamic flow environments. / text

This study investigates peculiarities of the filtration combustion (FC) of the gaseous fuel-air mixtures in a porous inertia media (PIM). Combustion wave velocities and temperatures were measured for hydrogen-air, propane-air and methane-air mixtures in the PIM at different mixture filtration velocities. It is shown that the dependences of the combustion wave velocities on the equivalence ratio are V-shaped, It was further confirmed that the FC in the PIM has more contrasts than similarities with the normal homogeneous combustion. One of the interesting observations in the present study, which is not common in normal homogenous combustion, is the shifting of the fuel-air equivalent ratio at the minimum combustion wave velocity from the stoichiometric condition (¢ = 1). For a hydrogen-air mixture, the fuel-air equivalence ratio at the minimum combustion velocity shifts from the stoichiometric condition to the rich region, while for the propane-air and methane-air mixtures the fuel-air equivalence ratio at the minimum combustion velocity shifts toward fuel-leaner conditions. The measured maximum porous media temperatures in the combustion waves are found to be weakly dependent on the mixture filtration velocities. In general, the effects of the mixture filtration velocities on the measured maximum porous media temperatures are not significant.

Two experiments were performed to investigate the interaction of a combustion wave with porous media. The first experiment was performed in a 1.22m long, 76mm wide, and 152mm high horizontal channel with a nitrogen-diluted stoichiometric methane-oxygen mixture at initial pressures of 20-50kPa. A layer of 12.7mm diameter ceramic-oxide spheres was placed along the bottom to partially obstruct the channel, leaving a gap of free space above. For a fixed gap height the bead layer thickness had very little effect on explosion propagation. For a fixed bead layer thickness the explosion propagation was strongly influenced by the gap height. For example, a 31% nitrogen diluted mixture at room temperature resulted in DDT for a gap height of 38mm at initial pressures of 30-50 kPa, but not for 109mm over the same pressures. The gap above the bead layer permits DDT as long as the gap height is larger than one detonation cell width. Propagation of the detonation wave over the bead layer is possible if the gap height can accommodate at least two detonation cells. For a 38mm gap, velocity measurements and sooted foil imprints indicate that the detonation undergoes successive failure and re-initiation, referred to as “galloping” in the literature. In the second experiment, the head-on collision of a combustion front with a layer of 3 and 12.7mm diameter ceramic-oxide spheres was investigated in a 61cm long, 76.2mm diameter vertical tube for a nitrogen-diluted stoichiometric ethylene-oxygen mixture at initial pressures of 10-100kPa. Four orifice plates were placed at the ignition end to accelerate the premixed flame to a “fast-flame” or a detonation wave. For fast-flames pressures recorded at the bead layer face were up to five times the reflected CJ detonation pressure. This explosion iv developed by two distinct mechanisms: a) shock reflection off the bead layer face and b) shock transmission into the bead layer and subsequent explosion therein. The measured explosion delay time (time after shock reflection from the bead layer face) was found to be independent of the incident shock velocity. Thus, it was shown that explosion initiation is not the direct result of shock reflection but is more likely due to the interaction of the reflected shock with the trailing flame. The bead layer was found to be very effective in attenuating the explosion and isolating the tube endplate. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-08-15 17:57:22.213

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