Digital Repository for faculty of Engineering

Abstract

Formation damage caused by inappropriate drilling, completion, work over and production schemes are a major cost to the oil and gas industry worldwide. Many potential pay zones have been misdiagnosed as nonproductive and payout on investment has often been delayed. The reservoir rock and resident fluids are essentially in a state of physicochemical and thermodynamic equilibrium. Disruptions in this equilibrium due to changes in pressure, temperature and fluid chemistry around the well bore region can create barriers to flow and yield lower production rates.Scale deposition is one of the most serious oil field problems primarily when two incompatible waters are involved .Two water types are called incompatible if they interact chemically and precipitate minerals when mixed .Typical examples are sea water, with high concentration of ,and formation water, with high concentration of ,and .Mixing of these types of water could cause CaSO4,BaSO4,and SrSO4 scales.In this research we analyzed pressure transient for different oil wells in Amal Field. The collected data as well as reservoir rock and fluids properties and well bore conditions and configuration was being inserted into MINITAB program to formulate mathematical model which can predict total skin in oil wells .We observed that model gives good results when we compared St calculated from build up test with St calculated from the model. A Mathematical Model was developed in this study which can be used by the production engineer in any sandstone reservoir in order to predict the possibility of damage forming in the well.The model can also be utilized to define the parameters causing the damage in the well from which adjustment can be made to reduce the chance of forming damage in the well bore.
عبد المحسن عاشور مقام (2008)

Abstract

Glass fiber reinforced plastic (GRP) pipes, are widely used in many of industrial applications, such as oil industries and petrochemicals plants to transport a wide range of different liquids like fresh water, sea water, lubricant oils, acids and caustic etc. This related to their lightness, corrosion resistance, strength durability, high tensile strength, low density, and ease of installation, so that selected as better than traditional metal pipes in such applications. But the internal surfaces of these pipes can be exposed to slurry erosion due to the impact of sand particles mixed with fluids at high velocity leads to create, catastrophic failure, which limits the useful life of pipes and their efficiency. Therefore the erosion is a critical parameter for design, selection and operation of hydraulic transportation system. This thesis has studied experimentally the Slurry erosion wear behavior of GRP pips at various parameters such as impact angles, and velocity of particles. Jet type erosion tester was used as rig and sand used as solid particle mixture with water. The results clearly indicated that the factors contribute to wear of Pipes. The erosion rate or weight loss increased as time, and velocity of solid particles increased, the effect of impact angles shifts from ductile behavior to brittle behavior depending on the value of erosion efficiency. The comparison between predicted and experimental results shows agreement within ±7% for Epoxy and ±8% for Polyester.
خالد عيسي المحجوبي (2013)

Abstract

In order to ensure the promise of anytime-anywhere communication to the customers, Mobile operators must be able to support a large number of users over a large coverage area. So Coverage and Capacity are important issues in the planning process for Third Generation (3G) mobile networks. The planning process aims to allow the maximum number of users sending and receiving adequate signal strength in a cell. In Code division multiple access (CDMA), the Coverage and capacity are not independent of each other as in GSM, it is interference-limited system, meaning that if the traffic increases, the serving cell radius decreases, hence the term cell breathing occurs. This work studies the capacity and coverage of a macrocell CDMA network. The cell breathing effect is studied and a new criteria to link Capacity and Coverage is developed, it is named by Capacity-Coverage Product; CCP. Different designations of CCP formula are given. The influencing of various system parameters on this CCP are studied. Knowing this CCP, the capacity and coverage become straight to estimate. The user distribution is very important issue. Most of previous studies treat user distribution as uniform. This thesis considers the case of non uniform user distributions where a more realistic distribution is chosen. A new interference distribution factor is initiated. The impact of this factor on the capacity and coverage is studied. Existing of Hotspot regions of traffic will cause coverage shrinkage. Installation of hotspot microcells BS inside existing macrocell BS is one possible solution to such situations. In this work a microcell is introduced within the macrocell and a new system parameters are obtained such that the coverage and performance are maintained while the capacity is increased.
محمد عبدالرزاق العالم (2007)

Abstract

In practical environment most of physical systems that are existed, have nonlinear behavior. In most cases the accuracy of these systems, and their responses aren’t acceptable. Therefore to improve the performance of these systems, a modern control methodology must be applied. In the case of nonlinear systems most problems can be divided into two basic types of nonlinear control problems; nonlinear regulation and nonlinear tracking problems. Due to existing of high nonlinearities parts in theses nonlinear systems the use of classical linearization methods don’t provide an acceptable level of accuracy and therefore these problems have gained a great attention in recent years; and there are numbers of methods can be found to solve these nonlinear problems, such as trail and error, feedback linearization, Robust control, Adaptive control, Gain-scheduling and…etc. In This thesis the feedback linearization is choose as a control methodology to solve these problems; The central idea of the feedback linearization approach is to algebraically transform a nonlinear system dynamics into a (fully or partly) linear one, so that linear control techniques can be applied. This differs entirely from conventional linearization (i.e., Jacobian linearization [4]) in that feedback linearization is achieved by exact state transformations and feedback, rather than by linear approximations of the dynamics.
فرج على عبدالسلام بشير (2008)

Abstract

In spite of their widely-spread use across the globe, the domestic solar water heaters are still subject to essential, technical difficulties that need to be deeply studied. Such technical impediments are latent in how appropriate to each other the different, mutually-dependent components of the system are; and how appropriate they are to the prevailing meteorological conditions of the application site which is still under research and development. This thesis presents a clear-cut, straightforward mathematical model that determines the basic factors influencing such systems, and, in specific, discusses the optimum design month as well as the optimum tilt angle of the solar collector, bearing in mind the contribution of the energy obtained to meet the targeted load. Furthermore, the study considers the required thermal capacity that should be provided by the solar collector. To avoid assumptions that could be unjustified in practice, and to get as precise results as possible, the study was thoroughly based on normalized mathematical parameters. In the case where the total demand for energy used in water heating is to be fully satisfied by the solar energy system, provided that the required temperature of the heated water is 45oC and consumption is 100 (litre/day) per person for a given house, the results of the study concluded that according to the climate information of Tripoli city, 32.68°N latitude, the optimum design month is December, the optimum tilt angle is 75°, and the solar collector area fulfilling the following specifications: Glazed type, Fr () = 0.58, and Fr UL= 4.00 (W/m2oC) is 2.83 square meters. On the other hand, the results suggest an optimum tilt angle of 50°, which is the same angle obtained by the traditional technique, and solar collector area of 1.6 square meters if up to 80% of demand is to be covered by solar energy.
علاء بلقاسم العلوني (2010)

Abstract

In this study, seepage phenomena through the foundation of Megenin dam are investigated. Most of the recorded dam’s failure around the world are related to seepage problems. Therefore to avoid failure of earth dams due to seepage, settlement, and piping, continuous field observations are essential. The Megenin dam is a 38 m high rock fill dam. A concrete cut-off wall and grout curtain were constructed below the dam body to prevent reservoir seepage through the foundation.The dam was constructed in 1972, for two main purposes; first to control floods for the cultivated fields downstream and to protect Tripoli city, secondly to collect water for irrigation. On 15thMay 2003 during the 3rd filling, the water level in the reservoir reached 271.86 m, while seepage water was observed in the wadi bed downstream of the main dam. This phenomena were also observed in previous times. The Piezometric water level was much higher compared to that previously measured. To assess the seepage phenomena and the impact on dam safety, the folowing were applied: the technique of ground penetrating radar survey (GPR), piezometric analysis, and temperature field evaluation. Constructed a flow net model for the dam.The results of the study showed that: GPR profiles describe critical zones in the dam site. Identify the water seepage paths from dam reservoir to down stream of dam.Determine the amount of total water seepage capacity through the dam foundation (Q= 0.08 Ɩ / s ).The essential points to avoid any problem that may occur in the future in Megenin dam due to seepage problems.
ناجي محمد شكشم (2009)

Abstract

In this thesis, the formulation of curved mixed finite strip element for cylindrical shells was developed utilizing the cubic –B3 spline function .Which is referred to in this thesis as a mixed finite strip method.The curved shell element is divided into a number of longitudinal curved strips and each strip element has two nodal line with four knot amended splines in addition to the existing of interference between the first and last ends amended splines in the whole three elementals .At each nodal line and each knot six degree of freedom in the form of three displacement components and three Moments or stress couples .These formulations are applied through selected two types of cylindrical shell roofs , which are circular cylindrical roofs and north light roofs.A software is developed to validate results and it can be used to handle one of boundary condition (simple- simple). The results obtained from the numerical formulation were compared with the analytical solution, where the accuracy and the convergence results were studied for different problems.
وداد إمحمد الصالحي (2010)

Abstract

In this thesis, we present a method for the design of multidimensional digital filters. This method is based on the use of genetic algorithm (GA). GA algorithm is proposed to optimize the coefficients of magnitude frequency response of digital filter design. GA algorithm is used to minimize a cost function representing the difference between the frequency response magnitudes of an ideal and obtained digital filters. Two types of filters namely, Finite Impulse Response (FIR) and Infinite Impulse Response (IIR) are implemented.The digital FIR filter exhibits a wide transition bands and ripples in the pass band which are considered as disadvantages in digital image processing. Therefore, the only way to obtain a steep transition FIR is to use high order which translates to high cost. An alternative way to avoid high cost filters is to use IIR digital filters. Such digital filters can provide steeper transition bands with lower order than equivalent FIR digital filters. Although FIR digital filters have the disadvantages of high cost in term of hardware realizations, they have the advantage of stability and linear phase. Since IIR digital filters have infinite impulse response, they are prone to unstability. Linear phase which is easy to obtain in FIR digital filters is hard to come by IIR digital filters. The low cost and fast filtering make the IIR digital filters attractive. The proposed GA is utilizing for the design of stable IIR filter with near linear phase constraints. Experimental results are presented for 1-D and 2-D digital IIR filter. From the magnitude-frequency response, the convergence of the proposed approach will be able to obtain global minima in a faster time.
ميسون محمد الزرقاني (2010)