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Articles 1 - 12 of 12
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Dynamic Modeling And Analysis Of Oscillatory Bioreactors, Yongchun Zhang
Dynamic Modeling And Analysis Of Oscillatory Bioreactors, Yongchun Zhang
LSU Doctoral Dissertations
Dynamic modeling of bioreactors is a challenging problem. The complexity of first principle models also make model validation and analysis very difficult and model-based controller design practically intractable. This thesis has focused on finding an effective tool for model dynamic analysis, construction of low-dimension model and simple and effective controller design. The validity of a biochemical reactor model often is evaluated by comparing transient responses to experimental data. Dynamic simulation can be rather inefficient and ineffective for analyzing bioreactor model. Bifurcation analysis is found to be a powerful tool for obtaining a more efficient and complete characterization of the model …
High Resolution Modeling Of Transport In Porous Media, Guangli Liu
High Resolution Modeling Of Transport In Porous Media, Guangli Liu
LSU Doctoral Dissertations
This dissertation presents research on the pore-level modeling of transport in porous media. The focus of this work is on high-resolution modeling, a rigorous approach that represents detailed geometry and first-principle physics at the streamline scale. Three major topics are presented in this dissertation: an efficient approach for solving Stokes flow in essentially arbitrary disordered porous media, high-resolution versus network simulations of dispersion phenomena, and a stochastic model for solving interfacial mass transfer from source spheres in porous media. First an approach was developed for solving the Stokes flow problem in a comparatively large, very heterogeneous two-dimensional porous media with …
Numerical Studies Of Reactive Polymer Flows In Porous Materials, Honggao Liu
Numerical Studies Of Reactive Polymer Flows In Porous Materials, Honggao Liu
LSU Doctoral Dissertations
This dissertation presents a new numerical model of reactive polymer flow in heterogeneous porous media. A moment representation of the log-normal polymer molecular weight distribution is used to model polymer as a multi-component species. Three leading moments are used to simulate the polymer transport and reaction processes in a two-dimensional porous medium. A new operator splitting technique that allows the moment equations for polymerization to be incorporated into a finite-difference transport model is developed. The novelty of this approach is the use of two different dependent variables (for the transport versus reaction parts of the problem). It is significant from …
The Effects Of Local Hydrodynamics On Mass Transfer In Disordered Porous Media, Gang Guo
The Effects Of Local Hydrodynamics On Mass Transfer In Disordered Porous Media, Gang Guo
LSU Doctoral Dissertations
Interfacial mass transfer in disordered media was studied experimentally and numerically. The dissolution of solid benzoic acid spheres in packed columns showed the existence of spatial variations in mass transfer coefficients in monodisperse and polydisperse packings at the same overall Peclet number. The concept of a local Peclet number (single-particle average) was introduced to quantify the effect of local hydrodynamics on local mass transfer. Correlations between Sherwood number and Peclet number having the form Shi=A·(xiPe)m were used to quantify data from various sites in each packing. These experiments also showed that the exponent m varies …
Analysis Of Diagnostic Testing Of Sustained Casing Pressure In Wells, Rong Xu
Analysis Of Diagnostic Testing Of Sustained Casing Pressure In Wells, Rong Xu
LSU Doctoral Dissertations
Over 8,000 wells in the Gulf of Mexico exhibit sustained casing pressure (SCP). SCP is defined as “any measurable casing pressure that rebuilds after being bled down, attributable to cause(s) other than artificially applied pressures or temperature fluctuations in the well”. The Minerals Management Service (MMS) regulations consider SCP hazardous and, in principle, require its elimination. In some cases the agency may allow continuing production at a well with SCP by granting a temporary “departure” permit. The departure permits are based on diagnostic tests involving pressure bleed-down through a 0.5-inch needle valve followed by closing the valve and recording pressure …
Mechanism Of The Nicofe Ternary Alloy Deposition, Yun Zhuang
Mechanism Of The Nicofe Ternary Alloy Deposition, Yun Zhuang
LSU Doctoral Dissertations
Electrodeposited NiCoFe ternary alloys are of interest for their magnetic and thermophysical properties. The reaction rates and resulting composition and current efficiency are often determined empirically, due to a lack of understanding of the electrodeposition mechanism and coupled mass transport. Therefore, the effects of electrolyte concentration, bulk pH and solution agitation are studied over a wide range of applied current densities to investigate the interrelated behavior of the partial reaction rates. The Fe rate during alloy deposition is independent of Co2+ and Fe2+ bulk concentrations, but is enhanced compared with its single metal rate. Both catalytic and inhibiting effects are …
Log-Derived Cation Exchange Capacity Of Shaly Sands : Application To Hydrocarbon Detection And Drilling Optimization, Gamze Ipek
LSU Doctoral Dissertations
Researchers at Louisiana State University, LSU, have introduced several petrophysical models expressing the electric properties of shaly sands. These models, to be used for hydrocarbon detection, are based on the Waxman and Smits concept of supplementing the water conductivity with a clay counterions conductivity. The LSU models also utilize the Dual Water theory, which relates each conductivity term to a particular type of water, free and bound, each occupying a specific volume of the total pore space. The main difference between these models and the other shaly sand models is that the counterion conductivity is represented by a hypothetical sodium …
Experimental Evaluation Of Control Fluid Fallback During Off-Bottom Well Control In Vertical And Deviated Wells, Fernando Sebastian Flores-Avila
Experimental Evaluation Of Control Fluid Fallback During Off-Bottom Well Control In Vertical And Deviated Wells, Fernando Sebastian Flores-Avila
LSU Doctoral Dissertations
This study measured the liquid fallback during simulated blowout conditions. The purpose of the study was to establish a basis for developing a procedure for controlling blowouts that relies on the accumulation of liquid kill fluid injected while the well continues to flow. The results from experiments performed with air, water, 10.5 ppg and 12.0 ppg mud in an experimental 48 ft flow loop at 0°, 20°, 40°, 60° and 75° deviation angles from the vertical, as well as results from full-scale experiments performed with natural gas and water based drilling fluid in a vertical 2787-foot deep research well, are …
Numerical Reservoir Characterization Using Dimensionless Scale Numbers With Application In Upscaling, Djuro Novakovic
Numerical Reservoir Characterization Using Dimensionless Scale Numbers With Application In Upscaling, Djuro Novakovic
LSU Doctoral Dissertations
Dimensionless space provides a tool for analyzing the behavior of complex systems described by mathematical relationships. The limited application of dimensionless variables in numerical reservoir simulation and experimental design motivated the development of a complete set of dimensionless scaling groups. Inspectional analysis yielded 8 dimensionless groups completely describing the flow system. Further analysis of fluid interaction reduced the number of dimensionless groups to 7. The newly developed dimensionless equations and groups were used for analytical and numerical reservoir characterization, quantifying the behavior of differential and difference equations employed in fluid flow in three-dimensional porous media. The behavior of the dimensionless …
Thermal Rheological Analysis Of Cure Process Of Epoxy Prepreg, Liangfeng Sun
Thermal Rheological Analysis Of Cure Process Of Epoxy Prepreg, Liangfeng Sun
LSU Doctoral Dissertations
The cure process of epoxy prepreg used as composite pipe joints was studied by means of differential scanning calorimetry (DSC), Bohlin Rheometer and other techniques. Isothermal DSC measurements were conducted between 110 and 220 oC, at 10 oC intervals. The results show that the complete cure reaction could be achieved at oC. The isothermal cure process was simulated with the four-parameter autocatalytic model. Except in the late stage of cure reaction, the model agrees well with the experimental data, especially at high temperatures. To account for the effect of diffusion on the cure rate, a diffusion factor was introduced into …
Numerical Study Of Water Coning Control With Downhole Water Sink (Dws) Completions In Vertical And Horizontal Wells, Solomon Ovueferaye Inikori
Numerical Study Of Water Coning Control With Downhole Water Sink (Dws) Completions In Vertical And Horizontal Wells, Solomon Ovueferaye Inikori
LSU Doctoral Dissertations
Approximately 2.5 billion dollars is spent annually to solve the problem of produced water in oil and gas wells. Downhole Water Sink (DWS) technology is one industry solution to control water coning in oil wells. DWS technology involves the segregated production of oil and water through separate completions with zonal isolation packer. However, several problems have been experienced in the application of the technology in watered-out oil wells. This study identified two factors that could aid in a better modeling of the technology in old vertical wells – inclusion of capillary transition pressures and relative permeability hysteresis. It also identified …
Analytical Model To Control Off - Bottom Blowouts Utilizing The Concept Of Simultaneous Dynamic Seal And Bullheading, Victor Gerardo Vallejo-Arrieta
Analytical Model To Control Off - Bottom Blowouts Utilizing The Concept Of Simultaneous Dynamic Seal And Bullheading, Victor Gerardo Vallejo-Arrieta
LSU Doctoral Dissertations
The current methods for off - bottom control of blowouts involve pumping kill fluid into the well through an injection string. These are the dynamic kill and the momentum kill. The dynamic kill, which is based on the steady state system analysis approach, and the momentum kill, that is loosely based on the Newton's Second Law of Motion, have been used extensively in off-bottom control of actual blowouts. A comprehensive study of these two concepts was performed. The review included an analytical analysis of the published design techniques for both of these methods. The application of these techniques to several …