Copper addition to palladium increases both activity and selectivity in the selective hydrogenation of 1,3-butadiene to n-butenes. The bimetal catalyst (Cu/Pd:2/1(atomic)) hydrogenates the diene to virtually 100% conversion without significant n-butene isomerization or butane formation. While at moderate conversions monometallic palladium is quite selective for n-butene production, 1-butene is quickly isomerized and saturated at higher conversions resulting from butadiene's inability to monopolize the active surface at lower partial pressures. Copper also promotes higher trans-2-butene selectivity and modifies the rate dependence on 1,3-butadiene from zero to negative order. These results suggest a donor "ligand" effect in which copper changes the palladium's electronic character. The apparent activation energy for 1,3-butadiene hydrogenation over palladium is 14.9 $\pm$ 0.2 kcal/mol.

In this thesis, we study two fundamental problems in the theory and experiment of interfaces in simple and complex fluids. The first problem concerns the critical behavior of the thickness of interface of simple fluids in two dimensions of space. We study this problem using both theory and computer simulations. In our theoretical study of this problem, the equilibrium interface is assumed, in accord with current ideas, to consist of an intrinsic interface of the non-classical van der Waals type broadened by capillary wave fluctuations. It is shown that the interfacial thickness exhibits a crossover with change of critical exponent from capillary wave behavior at low temperatures to intrinsic structure behavior at temperatures extremely close to the critical temperature. The location of the crossover temperature is determined by a critical amplitude ratio. In our computer simulation study of this problem, the interfacial thickness between two two-dimensional Lennard-Jones fluid phases is determined by using the method of molecular dynamics. Within statistical uncertainty, the results for the interfacial thickness are found to be consistent with the prediction of the non-classical van der Waals theory of the intrinsic interface. The second problem studied in this thesis concerns the wetting behavior of three-component surfactant systems. In a three-phase equilibrium system, the middle phase either wets or does not wet the interface between the upper and lower phases. In this work, we perform a systematic experimental search for wetting transitions between wetting and nonwetting behaviors in three-component systems water/n-alkane/C$\sb{\rm i}$E$\sb{\rm j}$, where C$\sb{\rm i}$E$\sb{\rm j}$ denotes the surfactant polyoxyethylene alcohol C$\sb{\rm i}$H$\sb{\rm 2i+1}$(OC$\sb2$H$\sb4$)$\sb{\rm j}$OH. It is found that two systems, water/n-hexadecane/C$\sb6$E$\sb2$ and water/n-octadecane/C$\sb6$E$\sb2$, exhibit a wetting transition lying at least 10$\sp\circ$C below the upper critical temperature, and one system, water/n-tetradecane/C$\sb6$E$\sb2$, exhibits a wetting transition lying 4.3$\sp\circ$C below the upper critical temperature.

A mathematical model is proposed for studying the dynamic behavior of drillstrings, focusing on the lower section of the drillstring known as the bottom-hole assembly or "BHA". In parallel, a comprehensive assessment of existing concepts and techniques for addressing drillstring dynamics is undertaken. Accounting for stiffness, damping, and inertial properties of the BHA and by incorporating appropriate excitations and boundary conditions, the dynamic characteristics of the BHA can be analyzed. The representation of the BHA stiffness is influenced by the underlying beam formulation assumptions, the stress-stiffening effect of axial loads, the elastic properties of the various materials used in the BHA, and the effective stiffnesses of special BHA components with complex geometries. Damping in the BHA involves both internal structural damping and damping resulting from its interaction with the surrounding viscous drilling fluid. Damping for the structure is accounted for using recent damping data leading to a smooth damping function which involves the vibration frequency and the drilling fluid density. Inertial properties of the BHA include its mass and the added mass effects of the fluid, both inside and outside the BHA, which is displaced through its motion. Frequency response characteristics for the structure are developed assuming a monochromatic exciting force. Both damped and undamped responses are simulated using a transfer function representation developed by modal superposition techniques. Sensitivity studies are performed to determine appropriate grid spacing for specific BHA problems of interest. Parameter studies reflect the influence of fluid added mass, weight-on-bit, boundary conditions, and the location of the excitation force. Excitation mechanisms for actual drilling assemblies are studied leading to a response superposition procedure which fully accounts for the behavior of BHA in drilling operations. Topics for further research are recommended.

Two often used permeability models, which are based on logarithmic mean of relaxation time distribution and irreducible water, were examined. The model based on irreducible water was found to be more suitable than the model based on mean value of relaxation time distribution when oil is present. The NMR response of North Burbank with partial saturation of air and water is different from those of other sandstones. The increase in the amplitude of the microporosity part of the relaxation time distribution after desaturation was observed for North Burbank. The clay lining a pore is diffusionally coupled with the large pores when 100% water saturated. After desaturation with air, the water in the microchannel is isolated and relaxes like water in an isolated micropore. It is generally believed that when the rock is water-wet, there is tendency for water to occupy the small pores and contact the majority of the rock surface. Water is typically relaxed by contact with grain surface, but oil at the center of the pore has no access to these surfaces and therefore can only relax by bulk processes. According to this study, $T\sb1$ distributions under partial saturation with brine/Soltrol followed the above behavior. However, for $T\sb2$ distributions, we found the Soltrol peaks for chlorite-coated North Burbank and highly shaly sandstones were broadened and shortened to shorter relaxation times due to diffusion and internal gradients effects. The diffusion effect can be supported by the same observation in 100% S$\rm\sb{w}$ condition. This suggests even if oil is prevented from contacting the grain surface, oil will not necessarily relax as a bulk oil in water-wet system.

Asphaltenes are the polydisperse fraction of heavy organics from petroleum whose phase behavior is important in petroleum production and processing because of its potential to precipitate and plug tubulars. The molecular framework used in this work is that van der Waals (dispersion) interactions dominate asphaltene phase behavior in oil. Using a proposed reservoir fluid fractionation method and an equation of state (EOS) asphaltene characterization method that requires only ambient condition titration data, the Statistical Associating Fluid Theory (SAFT) EOS was extended to model/predict asphaltene phase behavior in oil. Studies on model asphaltene systems (polystyrene-hexane, polystyrene-toluene-ethane, long-chain and short-chain n-alkanes, and phenanthrene-decane-methane mixtures) show that SAFT can describe the phase behavior of fluids dominated by molecular size and shape interactions. Comparison between predicted and experimental asphaltene stability and oil bubble point curves of a recombined oil and a model live oil measured in this work show good agreement. The asphaltene stability and the bubble point measurements for the two oils were made under reservoir conditions as functions of pressure, temperature, and dissolved gas concentration. Both theory and experiment show significant temperature effects on asphaltene stability and the asphaltene instability onset pressures are nearly linear functions of dissolved gas concentration at each temperature. Furthermore, both SAFT-calculated and experiment derived mixture solubility parameters/refractive indices along the asphaltene instability curves are nearly constant at each temperature. A SAFT investigation into the effects of asphaltene polydispersity shows that the lower molecular weight (MW) asphaltenes (including resins) play a significant role in stabilizing higher MW asphaltenes in oil, despite the inclusion of only dispersion interactions in the model. Resin's stabilizing effects on (polydisperse) asphaltene is greatest in the region of incipient asphaltene instability. In n-alkane titrations, SAFT shows that the heaviest asphaltenes will precipitate first, followed by the precipitation of smaller asphaltenes on further oil dilution. The ability to calculate changes in asphaltene MW distribution may be useful in deposition models.

Lateral vibrations are widely recognized as the leading cause of drill-string failures in oil well operations. The finite elements method formulation is used for the mathematical modelling. Due to the erratic nature of the forces at the drill-bit, a stochastic dynamics approach is followed. Both the method of statistical linearization, and the Monte Carlo method are used to analyze the system dynamics. Numerical results pertaining to data obtained by measurement while drilling tools are presented. The significance of the present study, over studies available in the literature, hinges upon the computational efficiency of the adopted piecewise linear model of the drill-string---well formation interaction and the derivation of information on the probability density function, and the power spectrum of the erratic drill-string motion. It is expected that this study will enhance the interest in using stochastic dynamics techniques in drilling system analysis and design.

The research presented was used to develop the surfactant/foam process for aquifer remediation. The surfactant/foam method was designed to address the problem of removing dense non-aqueous phase liquids (DNAPLs) spread throughout a somewhat heterogeneous aquifer. The developmental research included demonstrating the effectiveness of the surfactant/foam process and determining the effects that various parameters had on the technique. Parameters tested included the effects of different contaminants on foam, the effects of varying surfactant solution formulation, the effects of flow rate and slug size, and the effect of temperature on the process. The final design utilized a 4% surfactant solution at its optimal salinity, 11,500 ppm NaCl with trichloroethylene at room temperature and 10,250 ppm NaCl with field DNAPL at 12$\sp\circ$C. Trichloroethylene was used as a representative DNAPL for the laboratory work. Foam was generated with pressure regulated air injection rather than a rate constrained gas injection. This method allowed a high gas flow rate when little foam was present, and a lower, more maintainable, flow rate as foam was generated. The process was tested in several experiments in layered sandpacks in a two-dimensional model. The permeability ratios of the sand layers ranged from 7:1 to 20:1. Packings included both a high permeability sand overlying a low permeability sand and the opposite configuration. The experiments resulted in complete removal of TCE from the sandpacks after one to two pore volumes (PV) of surfactant injection. In contrast, surfactant floods without foam in the same packs required between 13 PV and 28 PV, depending on the sands' arrangement and permeability ratio. The surfactant/foam process was also tested in a larger scale two-dimensional model. Foam was successfully propagated across the eight foot length of the layered sandpack. A field demonstration was then carried out in a fifteen by twenty foot well pattern. The preliminary field results indicate that the surfactant/foam process recovered more DNAPL from the site than had been present initially due to contaminant migration into the well pattern. The final DNAPL saturation at the field site was approximately 0.0003 in the volume swept.

The deposition of material that has precipitated out of solution can cause problems that plague a variety of engineering and biological processes. Scale formation in cooling towers, boilers, and oil/gas operations are prevented with chemical inhibitors such as nitrilotris (methylene phosphonic acid). The release of this phosphonate from solid material is studied with batch and dynamic flow experiments. The corresponding observations can be incorporated into SqueezeSoft(TM), a computer program, written by the Rice University Brine Chemistry Consortium. This work attempts to examine SqueezeSoft(TM)'s ability to identify the placement of inhibitor during a squeeze treatment and the corresponding reactions that occur. SqueezeSoft(TM) has been found to correctly predict the profile of inhibitor injected into a column packed with core material. Because this program is based on theory and not on empirical findings, it can be expanded to other more general applications.

Petroleum refining processes provide the daily requirements of energy for the global market. Each refining process produces wastes that have the capacity to harm the environment if not properly disposed of. The treatment of refinery waste is one of the most complex issues faced by refinery managers. Also, the hazardous nature of these wastes makes them rather costly to dispose of for the refineries. In this thesis, system analysis tools are used to design a program that allows for the selection of the optimal control, minimization and treating options for petroleum refinery waste streams. The performance of the developed model is demonstrated via a case study. Optimal mitigation alternatives to meet the emission reduction targets were studied by evaluating their relative impact on the profitable operation of the given facility. It was found that the optimal mitigation steps was to reduce emission precursors by conducting feed switches at the refinery. In all cases, the optimal solution did not include a capital expansion of the emission control facilities and equipment.

No description available.