Thesis (doctoral)--Rheinisch-Westfälische Technische Hochschule Aachen, 1994.

Thesis (doctoral)--University Fridericiana Karlsruhe, 2002.

Produced water is formed in underground formations and brought up to the surface along with crude oil during production. It is by far the largest volume byproduct or waste stream. The most popular preference to deal with produced water is to re-inject it back into the formation. Produced water re-injection (PWRI) needs a treatment before injection to prevent formation blockage. Due to the increase of produced water during oil production in the west of Kuwait, an effluent treatment and water injection plants were established and commissioned in 2004 so that produced water could be used for re-injection purposes. It is estimated that oil wells in the west of Kuwait produce 15 to 40 % of produced water. The main aim of this treatment train is to reduce not only the oil-in-water amount to less than 10 ppm, but also total suspended solids to 5 ppm which is the maximum allowable concentration for re-injection and disposal. Furthermore, with respect to the upper limit for injection, the maximum number of particles between 5 and 8 microns is 200 in 0.1 ml. In practice the number is found to exceed this limit by 10 times...

It is estimated that the shallow reservoirs of Ugnu, West Sak and Shraeder Bluff in the North Slope of Alaska hold about 20 billion barrels of heavy oil. The proximity of these reservoirs to the permafrost makes the application of thermal methods for the oil recovery very unattractive. It is feared that the heat from the thermal methods may melt this permafrost leading to subsidence of the unconsolidated sand (Marques 2009; Peyton 1970; Wilson 1972). Thus it is necessary to consider the development of cheap non-thermal methods for the recovery of these heavy oils. This study investigates non-thermal techniques for the recovery of heavy oils. Chemicals such as alkali, surfactant and polymer are used to demonstrate improved recovery over waterflooding for two oils (A:10,000cp and B:330 cp). Chemical screening studies showed that appropriate concentrations of chemicals, such as alkali and surfactant, could generate emulsions with oil A. At low brine salinity oil-in-water (O/W) emulsions were generated whereas water-in-oil (W/O) emulsions were generated at higher salinities. 1D and 2D sand pack floods conducted with alkali surfactant (AS) at different salinities demonstrated an improvement of oil recovery over waterflooding. Low salinity AS flood generated lower pressure drop, but also resulted in lower oil recovery rates. High salinity AS flood generated higher pressure drop, high viscosity emulsions in the system, but resulted in a greater improvement in oil recovery over waterfloods. Polymers can also be used to improve the sweep efficiency over waterflooding. A 100 cp polymer flood improved the oil recovery over waterflood both in 1D and 2D geometry. In 1D geometry 1PV of polymer injection increased the oil recovery from 30% after waterflood to 50% OOIP. The tertiary polymer injection was found to be equally beneficial as the secondary polymer injection. It was also found that the combined application of AS and polymer did not give any major advantage over polymer flood or AS flood alone. Chemical EOR technique was considered for the 330cp oil B. Chemical screening studies showed that microemulsions could be generated in the system when appropriate concentrations of alkali and surfactant were added. Solubilization ratio measurement indicted that the interfacial tension in the system approached ultra-low values of about 10-3 dynes/cm. The selected alkali surfactant system was tested in a sand pack flood. Additionally a partially hydrolyzed polymer was used to provide mobility control to the process. The tertiary injection of ASP (Alkali-Surfactant-Polymer) was able to improve the oil recovery from 60% OOIP after the waterflood to almost 98% OOIP. A simple mathematical model was built around viscous fingering phenomenon to match the experimental oil recoveries and pressure drops during the waterflood. Pseudo oil and water relative permeabilities were calculated from the model, which were then used directly in a reservoir simulator in place of the intrinsic oil-water relative permeabilities. Good agreement with the experimental values was obtained. For history matching the polymer flood of heavy oil, intrinsic oil-water relative permeabilities were found to be adequate. Laboratory data showed that polymer viscosity is dependent on the polymer concentration and the effective brine salinity. Both these effects were taken into account when simulating the polymer flood or the ASP flood. The filtration theory developed by Soo and Radke (1984) was used to simulate the dilute oil-in-water emulsion flow in the porous media when alkali-surfactant flood of the heavy oil was conducted. The generation of emulsion in the porous media is simulated via a reaction between alkali, surfactant, water and heavy oil. The theory developed by Soo and Radke (1984) states that the flowing emulsified oil droplets clog in pore constrictions and on the pore walls, thereby restricting flow. Once captured, there is a negligible particle re-entrainment. The simulator modeled the capture of the emulsion droplets via chemical reaction. Next, the local water relative permeability was reduced as the trapping of the oil droplets will reduce the mobility of the water phase. This entrapment mechanism is responsible for the increase in the pressure drop and improvement in oil recovery. The model is very sensitive to the reaction rate constants and the oil-water relative permeabilities. ASP process for lower viscosity 330 cp oil was modeled using the UTCHEM multiphase-multicomponent simulator developed at the University of Texas at Austin. The simulator can handle the flow of three liquid phases; oil, water and microemulsion. The generation of microemulsion is modeled by the reaction of the crude oil with the chemical species present in the aqueous phase. The experimental phase behavior of alkali and surfactant with the crude oil was modeled using the phase behavior mixing model of the simulator. Oil and water relative permeabilities were enhanced where microemulsion is generated and interfacial tension gets reduced. Experimental oil recovery and pressure drop data were successfully history matched using UTCHEM simulator. / text

During carbon dioxide (CO₂) sequestration, CO₂ injection suffers from viscous fingering and low sweep efficiency. In addition, the lower density of CO₂ compared to in-situ brine leads to the possibility of sequestered CO₂ rising up through the relatively permeable path in the cap rock and being emitted back out to the atmosphere. This research proposes a mechanism of CO₂-in-brine emulsion stabilization by surface-coated nanoparticles as a potential cure for these problems. This mechanism is studied in detail by conducting a series of core floods to investigate the interactions between nanoparticles and the surroundings such as fluids and rock surfaces during nanoparticle transport in sedimentary rocks. The experiments presented here use n-octane as a low-pressure analog fluid to supercritical CO₂ as they share several key characteristics. Comparisons of pressure drop and CT images from drainage displacement experiments with and without nanoparticles show that nanoparticle-stabilized emulsions were generated in-situ in highly permeable and homogeneous Boise sandstones tested in this study. Roof snap-off is proposed as the key mechanism for generating the emulsions. The imbibition experiment presents a case where Roof snap-off does not occur. The pressure drop for the control experiment and the nanoparticle experiments confirmed that without Roof snap-off nanoparticles do not affect the dynamics of the displacement except for the viscosity increase of the aqueous phase. However, it was inferred from the saturation profiles and effluent concentration history that nanoparticles were traveling faster than the aqueous phase in which they were dispersed and accumulating at the main displacement front. Inaccessible pore volume is proposed as a mechanism responsible for the accelerated transport of nanoparticles. The single-phase flow experiments demonstrate the accelerated transport of nanoparticles in porous media that was invoked to explain observations during imbibition displacement. During these experiments, tracer and nanoparticles were simultaneously injected into a porous medium and their effluent concentrations were monitored using a UV-Vis detector. The results show that nanoparticles traveled faster than the tracer in Boise and Berea sandstones studied in this research. Two-site model developed by Zhang (2012) was used to fit the data. Simulations suggested that the two-site model could replicate the overall shape of the experimental data when a slug of nanoparticle dispersion was injected, but it was not able to accurately predict the leading edge and the trailing edge of the effluent concentration history, where nanoparticles appeared before tracer due to accelerated transport. To account for the enhanced transport of nanoparticles, a modified two-site model with an acceleration factor, E, is proposed. The resulting fit matched the experimental data better than the original two-site model. / text

Microfluidic droplets are a powerful tool for screening large populations of cells, molecules, and biochemical reactions. Droplet systems are able to encapsulate, incubate, screen, and sort millions of samples, providing access to large number statistics that make searching for rare events feasible. Initial development of the microfluidic devices and methods has attracted applications in biology, biochemistry, and material science, but the set of tools remains incomplete. Efforts are required to develop micro-scale droplet analogs for all bulk-scale bench top procedures and instruments. The droplet analogs must be versatile, robust, and process samples rapidly. / Engineering and Applied Sciences

The ability of surface-treated silica nanoparticles to stabilize oil/water emulsions presents us with many interesting avenues of study. The goal of this research is to assess the ability of a dispersion of specially surface-treated nanoparticles to stabilize an oil/water emulsion of prescribed internal structure created by flow within a fracture. We hypothesize that for a set of conditions (nanoparticle concentration, salinity, aqueous to organic phase ratio) a critical shear rate exists. That is, for flow rates that exceed this critical shear rate, an emulsion can be created. Flow experiments were conducted within fractured Boise sandstone and cement cylinders. The Boise sandstone core (D = 1 in and L = 12 in) was cut down its length and propped open to a specific aperture with beads. The fracture was saturated with dodecane then displaced with nanoparticle dispersion, and vice versa while pressure drop across the fracture was recorded. Class H cement cylinders (D = 1 in and L = 3 in) were allowed to set, then failed in compression to create a rough-walled fracture along their length. These fractured cement cylinders were then sealed and encased in epoxy to isolate the fractures. CT scans of the encased fractures were used to determine the aperture width, which is utilized when calculating the shear rate inside of the fracture maintained during an experiment. A dispersion of surface-modified silica nanoparticles and decane were coinjected into both the Boise sandstone and cement fractures and the pressure drop was measured across the fractures at a variety of shear rates. The effluent of each experiment was collected in sample tubes. Observation of the effluent and pressure drop data both support our hypothesis of emulsion generation being possible once a critical shear rate has been reached. Alteration of the injected phase ratio and increased residence time of the two phases inside of a fracture both affect the amount of emulsification occurring within the fractures. Increasing the residence time of both phases within a fracture allows for more opportunities for emulsification to occur, resulting in a greater amount of emulsion to be generated. Injection of high or low volumetric ratios of nanoparticle dispersion to organic phase results in little amounts of emulsion generation; however, between the nanoparticle dispersion to organic phase ratios of 0.25:1 and 2:1 significant amounts of emulsion are generated. / text

This thesis investigated the perception of salt taste in two novel strategies for inclusion of NaCl in liquid foods: water-in-oil (w/o) emulsions and mucoadhesive biopolymer solutions. The major factors influencing w/o emulsion stability and perception were evaluated and a response surface model was developed. The amount of dispersed aqueous phase was the most significant factor affecting stability and perception. NaCl stabilized the emulsions and depressed salt sensory perception at elevated concentrations due to its interaction with the emulsifier polyglycerol polyricinoleate. Future research should elaborate events during oral processing of w/o emulsions. Biopolymer mucoadhesive character and concentration effects were also investigated. Mucoadhesion did not enhance salt taste. Above c*, there was a significant depression of sensory intensity, enhanced in polymers with hyperentanglements in solution. The depressive concentration effect may mask the effects of mucoadhesion. Future research should also inspect the influence of thickened hydrocolloid microstructure on perception. / The Advanced Foods and Materials Network

In the last decade processes known as living/controlled radical polymerizations (L/CRP) have been developed which permit the synthesis of high-value specialty polymers. Currently, the three processes that have demonstrated the most potential are: reverse addition fragmentation chain transfer polymerization (RAFT), atom transfer radical polymerization (ATRP) and stable free radical polymerization (SFRP). While each process has their strengths and weaknesses with regard to specific polymers and architecture, the viability of these systems to industrial scale production all lie in the ability to perform the polymerization in a water based system because of process, environmental and economic advantages. The most effective method of controlling the polymerization of vinyl acetate in bulk has been RAFT. We have developed a miniemulsion RAFT polymerization using the xanthate methyl (ethoxycarbonothioyl)sulfanyl acetate. The miniemulsion is stabilized with 3 wt% sodium lauryl sulfate, initiated with the azo-based water-soluble VA-060. The main focus of this research was adapting ATRP to a miniemulsion system. It was determined that ionic surfactants can be successfully employed in emulsion-based ATRP. The cationic surfactant cetyltrimethylammonium bromide provides excellent stability of the latex over a range of surfactant loadings (allowing the particle size to be easily manipulated), at temperatures up to 90 C, for a wide variety of ATRP formulations. A new method of initiation was developed for reverse ATRP, using the redox pair hydrogen peroxide/ascorbic acid. This nearly eliminated the induction period at the start of the polymerization, increased the polymerization rate 5 fold and, surprisingly, enabled the formation of well-controlled polymers with a number-average molecular (Mn) weight approaching 1 million (typically ATRP is limited to ~200 000). The ability to control the particle size and the number of polymer chains (through the target Mn) over a wide range of values allowed us to determine that ATRP is influenced by compartmentalization effects. The knowledge gained from our work in L/CRP was used to develop the surfactant-free SFRP of styrene. A multi-stage approach was adopted starting from dilute styrene/water solutions to favor the formation of the alkoxyamine and short chain SG1-oligomers (stage one) before the addition of the majority of the styrene (stage two). / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2007-09-14 12:09:32.266

This thesis is an investigation into the development of amidine and guanidine based compounds to be employed as switchable surfactants. The surface activity of these molecules can be triggered by reaction with a benign gas, CO2. The ultimate application of these surfactants was to be used as emulsifying and demulsifying agents of crude oil and water emulsions. Synthesis and characterization of the following desired bases: N’-octyl-N,N-dimethylacetamidine (1), 2-octyl-2-imidazoline (2), 1-methyl-2-octyl-2-imidiazoline (3), N’-(4-heptylphenyl)-N,N-dimethylacetamidine (4), N’-(4-(octyloxy)phenyl)-N,N-dimethylacetamidine (5), N’-(4-(methyloxy)phenyl)-N,N-dimethylacetamidine (6), and N-octyl-N',N',N",N"-tetramethylguanidine (7) was carried out. Their solubility in water was quantified with NMR spectroscopy. All bases were reacted with CO2 and H2O to form bicarbonate salts, of which in situ characterization was achieved by IR and NMR spectroscopy. Percent conversion to the protonated forms at elevated temperatures was determined using NMR spectroscopy. A direct correlation between switchability and basicity was observed, as the strongest bases possessed the largest conversions to the protonated species, even at higher temperatures. The enthalpy of protonation was determined for each base through calorimetry experiments. These compounds were tested as demulsifying surfactants of crude oil and water emulsions. Demulsifying ability was determined to differ greatly with the head group structure of the various surfactants. / Thesis (Master, Chemistry) -- Queen's University, 2009-10-27 16:56:13.631