Digital Repository for faculty of Engineering

Abstract

Here asphaltene precipitation in petroleum reservoirs during natural depletion and miscible gas injection is modeled for two distinct and new methods (polymer solution and Scott-Magat theory). The first model is based on the polymer solution theory, which is a combination of Miller's combinatorial term with a modified residual term of the original Flory-Huggins theory. The second one is based on the Scott Magat theory to represent solid-liquid equilibria. The models has also been coupled with Peng Robinson equation of state (PR EOS) to describe the phase behavior of asphaltene compounds in crude oil and predict the amount of asphaltene precipitation during injection of carbon dioxide for the miscible displacement of asphaltic crudes. The model treats asphaltene within crude oil as a single pseudocomponent represented by an average molecular weight and molar volume and solubility parameter . The results of both models show an acceptable and good agreement between the real data (field and experimental) and those of the models. As it can be seen from the obtained results of those of the two models, it seems that application of the lattice or polymer solution theories (based on The Miller's combinatorial term) could give better results that are more close to real data.
وداد بلعيد حميدات (2009)

Abstract

History of project management return to ancient times since the construction of the great projects that immortalized in history like pyramids, Wall of China, the Gardens of Babylon And many more projects that still witness to the civilizations until today. And for certainly, that difficult and complex project needed many equipment, materials, and human resources... And there is no doubt, that it had been using an administrative system in these projects, but so far, no historian has found any documented information about how they did it! Our present time of competition and development in all fields, specially industry, which it’s measurement is the most important criteria for measuring the development of any community, and there is many types of industries, including the construction industry, which has grown clearly on all parts of Libya, whether in infrastructure projects or investment projects. Despite the important role of construction projects in Libya, but it is suffering through it’s life cycle to a many of problems, leading to delay the completion of these projects. And in this thesis a study applied on construction projects to obtain depending on the questionnaire prepared in advance in compliance with elements of the academic view, and then doing the necessary statistical and computer-aided analysis and the use of modern software then discuss the results in details. Thesis includes the explanation and the analysis of findings that has been done for the problems and determines the impact of these problems on construction projects on (duration, cost and quality)
محمد رمضان المشري (2013)

Abstract

It is found in the literature that correlations and methods used in the determination of the lifting capacity for vertical wells cannot be applied directly for calculating the lifting capacity for horizontal well section without modifications. It is therefore necessary to formulate a new experimental technique from which new lifting capacity correlation is deduced which will be applied for the determination of the lifting capacity for the horizontal well section.The phenomena of cuttings concentration accumulated in the bottom of the horizontal section which is present in horizontal wells, does not exist in the vertical sections of the well. This problem makes it necessary to conduct an experimental work in a horizontal well simulator, to exactly simulate the drilling operation in the horizontal section of the well, from which lifting capacity values are determined for different mud formulations containing different cuttings sizes, concentrations and different mud reheology circulation at different flow rates. The objective of this study is to investigate the behavior of whole cleaning in the horizontal well section and to determine the factors effecting the cleaning capacity of the mud in this section. Also to deduce correlations relating the lifting capacity of the mud in the horizontal section of the well with various drilling parameters and mud circulation conditions. This study is conducted in the laboratory using a horizontal well simulator consists of the circulating mud component similar to that present in actual drilling operations. The experimental work used consists of using four muds formulation systems mixed with different cutting sizes and concentrations. The returned cuttings are extracted from mud return line for selected given time increments and accordingly their weights and sizes are determined. It is concluded that there is an optimum cutting size for maximum lifting capacity for each cutting concentrations used. The lifting capacity observed form the experimental results is not only dependent on mud velocity, but it is also dependent on the cutting concentrations used. It was observed that when cleaning the system after each experiment, accumulation of rock cuttings were present in the bottom of the horizontal section of the model. In this study a lifting capacity correlation relating the lifting capacity with mud flow rate, cutting size, cutting concentration, mud density, and mud viscosity is generated for the horizontal section of the well. Therefore it recommended that cleaning of the horizontal section of the well should be conducted frequently (consecutively) after each drilling time increment, which means that the drilling operation is stopped and the mud circulation rate is set to maximum. A maximum mud circulation rate is needed in order to ensure that the cuttings generated by the bit are removed efficiently in the horizontal section. It is therefore recommended during drilling the horizontal section a sequential drilling and cleaning technique should be applied.
عادل محمد جالوتة (2010)

Abstract

Most of the controllers used in industries are of PID type, this is because they have simple structure and their usage is well known among industrial specialists. The tuning of controllers is the crucial issue in the overall control loop design in order to obtain a satisfactory performance response. Over the past decades many tuning techniques were developed to adjust the controller parameters. Most of these techniques have the disadvantages of giving a combination of heavy oscillatory response, large overshoot, and long settling and rise time. This work presents a fuzzy logic-PID scheme, the basic concept behind this scheme is to combine the conventional PID controller with the use of fuzzy logic concept. The PID controller regulates the process, while the fuzzy logic part adjusts the proportional gain of the controller. This scheme will be used to overcome the previous disadvantages and to improve the performance of the conventional controller. The effectiveness of fuzzy logic-PID scheme has been analyzed through computer simulation using MATLAB. The results have been compared with those of Ziegler-Nichols, Chien-Hrones-Reswick, Cohen-Coon, Optimum PID controller and a PID with constant and variable weighting factor. This comparison has shown a considerable improvement in the performance of the transient response for different simulated processes
علي عبدالرحمن بن عاشور (2008)

Abstract

Reinforced concrete slabs are among the most common structural elements, but despite the large number of slabs designed and built, the details of the elastic and plastic behavior of slabs are not always appreciated or properly taken into account. The problem for the designer is to decide which method is most appropriate for a given slab. It must be determined whether the chosen method satisfies strength and serviceability requirements and whether the solution is economical from both a design and construction point of view. The purpose is to examine different methods of two-way slab design and compare the results to assess the relative merits of design methods. However, commercially available finite element softwares are not designed for this task as most of them have been developed to be used as verification rather than design tools. 'Home-written' software can be designed to achieve this task, however it may suffer from serious drawbacks such as bugs, lack of user friendliness, lack of generality, and unproven reliability.
ماجد يوسف زقوت (2009)

Abstract

Structural analysis is the mathematical calculation of forces, stresses, and deflections within structures, either as part of the design of those structures or as a tool in understanding the performance of existing structures. There are two broad classes of analysis: classical methods and matrix methods. The distinction is based on theory: classical methods were developed to analyze particular types of simple structures and provide answers by means of analytical formulation; matrix methods which are more general and systematic so that they can be conveniently handle structures of any size and complexity, and are computer-oriented using matrix computations. Both approaches, however, are based on the same three fundamental relations: equilibrium, constitutive, and compatibility. The solutions are approximate when any of these relations are only approximately satisfied. Finite element analysis, which originated as an extension of matrix analysis to surface structures (e.g., plates and shells), has now developed to the extent that it can be applied to structures and solids of practically any shape or form. The application of these methods usually requires an understanding on the part of the analyst of the structural analysis principals. The objective of this thesis is to give comparative study of the methods applied in the structural analysis: Classical, Matrix, and Finite-Element.
مالك أحمد النفاتي (2009)

Abstract

The average recovery factor calculated for the whole reservoir is higher than the average recovery factor calculated from averaging the individual well recovery factor. The integrated recovery factor calculated from each well should be compared with recovery factor calculated for the reservoir as a whole using the material balance equation or the volumetric methods as a basis for the calculations. The difference between the two values is anindication of an inadequate well spacing for the reservoirIf (Np/N) each ≈ (Np/N)whole the distribution of the wells for the reservoir is adequate .If (Np/N) each < (Np/N)whole the distribution of the wells in the reservoir is inadequate .This indication of excess in number of wells .If (Np/N) each > (Np/N)whole the distribution of the wells in the reservoir is inadequate .This indication of the reservoir needs infill wells to be drilled.The number of infill wells depends on the relationship between recovery factor and number of wells. The infill wells location in the reservoir should be at high hydrocarbon pore volume and also it should be located in the trend of the easiest permeability path of oil movement.It was concluded that the number of wells existing in the Sharara field is not adequate therefore we recommend to increase the number of the wells as per the method enclosed in this study. The results of this study indicate that the calculated oil production decline rate constant is different from well to another which is an indication of variations of water influx into the reservoir.
مختار محمد غدير (2008)

Abstract

The contribution of this thesis is to improve the understanding of flame dynamics in the gas turbine combustor. The dynamic of diffusion flame or the flicker of a flame, as they are called in the research community is an important physical parameter associated with the characteristics of a combustion process. The flicker frequency of a flame reflects its oscillation of radiation, pressure and other characteristics, and plays an important role in flame structure, radiation field and energy efficiency. In addition, flickering frequency could be an indication of flame instability. It is therefore important to be able to measure the flicker of a flame in order to achieve an in depth understanding of the fundamental aspects of combustion processes and to develop a technique suitable for advanced flame monitoring in electrical power generation, gas turbine, boiler, and etc... To understand the phenomena related to thermoacoustic, a simple Rijke-type tube combustor was built and studied. Extensive experimental results, as well as theoretical analyses related to the Rijke tube is presented in this project. The results, attributable to both the analyses and the experiments, help explain all the phenomena affecting the acoustic pressure in the combustor. The conclusion is that there are three separate yet related physical processes affecting the acoustic pressure in the tube. To understand this parameter, a simple system was built and studied. Extensive experimental results are presented in this project to measure a flicker signal. In order to begin to understand what flicker parameter is, it was necessary to collect and analyze the light signal produced by light cell from burner which operates on diffusion flame, the chosen method for data collection was a light data acquisition system, the acquired light signal was then analyzed with Lab VIEW software, the software’s main feature is that it was capable of defining the light signal in many parameters, the most important of which were: power spectrum, cross correlation and the light wave shape. The power spectrum gave a concise presentation of the main frequencies which constituted the flicker signals, and their relative amplitudes. this was very helpful in determining the frequency of the diffusion flame (flicker signal).flame height and flame lift off also have been studied in this project. Finally applied this technique and all this Procedures at alkhoms power plant gas turbine combustor and then we compare the results with other technique like CCD camera and Photomultiplier we option the same results with cheaper devices
محمد عمران محمد (2013)