Dissolution Of A Nonaqueous Phase Liquid In Saturated Porous Media

The transport and dissolution of residual non-aqueous phase liquids (NAPLS) trapped in water saturated porous media is a problem pertinent to both environmental and petrochemical industries. In this work we have quantitatively examined the complete dissolution of residual entrapped NAPL at the pore-scale in three dimensions using refractive index matching techniques along with planar laser induced fluorescence. The results yielded pore-scale information regarding ganglia volume, surface area, and position over time at various Capillary numbers. We found that with increasing Capillary numbers, the time for total dissolution decreased. In addition, it appears that large ganglia exhibit fractal area to volume scaling. We were also able to examine the distributions of the ganglia in the direction of flow over time. The use of low-frequency flow pulsations as a removal technique was also examined. A two dimensional micro model was used for these studies. We found that for this system, lower frequencies and higher amplitudes were more effective in NAPL removal due to breakup and mobilization. We also examined the effect of increasing amplitude and continuous versus pulsed stimulation. In addition, mass transport in the presence of a surfactant was also enhanced due to flow pulsation with lower frequencies and higher amplitudes again being most effective.

This monograph provides state-of-the-art theoretical and computational findings from investigations on physical and chemical dissolution front instability problems in porous media, based on the author’s own work. Although numerical results are provided to complement theoretical ones, the focus of this monograph is on the theoretical aspects of the topic and those presented in this book are applicable to a wide range of scientific and engineering problems involving the instability of nonlinear dynamic systems. To appeal to a wider readership, common mathematical notations are used to derive the theoretical solutions. The book can be used either as a useful textbook for postgraduate students or as a valuable reference book for computational scientists, mathematicians, engineers and geoscientists.

Porous media, and especially phenomena of transport in such materials, are an impor1ant field of interest for geologists, hydrogeologists, researchers in soil and fluid mechanics, petroleum and chemical engineers, physicists and scientists in many other disciplines. The development of better numerical simulation techniques in combination with the enormous expansion of computer tools, have enabled numerical simulation of transport phenomena (mass of phases and components, energy etc. ) in porous domains of interest. Before any practical application of the results of such simulations can be used, it is essential that the simulation models have been proven to be valid. In order to establish the greatest possible coherence between the models and the physical reality, frequent interaction between numericians, mathematicians and the previously quoted researchers, is necessary. Once this coherence is established, the numerical simulations could be used to predict various phenomena such as water management, propagation of pollutants etc. These simulations could be, in many cases, the only financially acceptable tool to carry out an investigation. Current studies within various fields of applications include not only physical comprehension aspects of flow and energy or solute transport in saturated or unsaturated media but also numerical aspects in deriving strong complex equations. Among the various fields of applications generally two types of problems can be observed. Those associated with the pollution of the environment and those linked to water management. The former are essentially a problem in industrialized countries, the latter are a major source of concern in North-Africa.