المستودع الرقمي لـجامعة طرابلس

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

Lexical competence can be defined as one's ability to use words differently and fully. This study is an attempt to investigate the effective techniques for testing the lexical competence in foreign language teaching. The study consists of four chapters. Chapter one is an introduction to the study. It focuses on the background of the study, and the problem of the study as well as the purpose and the hypotheses of the study. Chapter two deals with the definitions, characteristics, types and methods for testing lexical competence were given. This chapter also focuses on the testing language skills and what to test in testing learners' lexical competence. Chapter three is the practical part of the study. It includes subjects of the study and data for the study. The data consisted of the students' test and the teachers' questionnaire with their analysis and results. Chapter four is concerned with the concluding remarks that have been drawn from the study. Some recommendations on the appropriate use of testing vocabulary are also suggested in order to overcome the teachers and the student’s problems for techniques in testing and teaching lexical competence.
حميدة علي الباوندي (2015)

Abstract

Managerial accounting plays an important role in organizations through providing information which helps the management in carrying out its duties and achieving it's goals efficiently and effectively .The thesis discusses and covers the main reasons behind the weakness of planning , control and performance evaluation processes in today's modern business environment , where this weakness is mainly caused by the managerial accountant not using modern information technology (I T) in providing necessary information needed by management , which resulted in an ineffective planning and control and a weak performance evaluation, despite the fact that One of the main objectives of managerial accounting in modern business environment is to provide necessary information for planning , control and performance evaluation processes .This concept lead the researcher to choose the subject of the thesis in an attempt to figure out the positive impact of using IT in providing information for the purpose of planning , control and performance evaluation.The thesis also targets the classical role of the managerial accounting , where it stands today in a modern business environment using widely IT facilities and relying on its out comes .
أمين عبد الله محمد الدرناوي (2009)

Abstract

Mixed chromium oxides with some divalent metals such as Fe, Co, Ni, Zn,Cd and Hg were prepared by two ways:- Coprecipitation of carbonates of the intended metals then calcination of the precipitates. Calcination of ground mixtures of oxy salts that are easilydecomposable.The produced mixed oxides were characterized using X- ray diffraction and the results were matched with those of A.S.T.M (Americation society of testing materials) and agreement was observed with the patterns of the intended compounds. The particle size was calculated from the profile of the diffraction peaks. Thermal behavior (TGA and DTA) was investigated and the thermodynamics and kinetics factors were calculated. The D.C. electrical conductivity was measured at room temperature and higher temperatures from where the activation energy of conduction was calculated. The materials prepared proved to behave as semiconductors in the investigated range of temperature.
حنان علي عبد السلام الشنطة (2009)

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)