Sharif Digital Repository

The purpose of this research project was to improve the performance of TEG liquid membrane in separation of gas mixtures by adding zeolite LTA nanoparticles. Therefore, the NaA zeolite particles with nano size were synthesized with hydrothermal method at optimized condition. The supported liquid membrane with hydrophilic PVDF membrane and triethylene Glycol (TEG) was prepared in two different conditions. In the first one, the pores of the supporting membrane were filled with triethylene Glycol, whereas in the second one the pores were filled with the mixture of triethylene Glycol along with the 5 wt% and 10 wt% zeolite nanoparticles. The performances of prepared membranes were investigated... 

Asphaltene deposition on reservoir rocks occurs during natural depletion as well as miscible injection processes. It causes reduction of effective pore space and consequent impairment of the ability of oil to flow through reservoir. Therefore, deposition of asphaltene causes significant formation damage and wellbore plugging, requiring expensive and difficult cleanup procedures. Thus it is necessary to be able to consider the onset, amount of deposition and also consequent damage of permeability and porosity reduction due to various factors. The objective of current work is to conduct experimental and simulation study of asphaltene deposition dynamics in one of the Iranian reservoirs. In... 

Real modeling of ceramic foam filters, because of their specific tortuosities is not possible and in case of possibility of real modeling of pores in filters, because of restriction of element’s dimensions, the number of elements increases and model can’t be run in a reasonable time with common computers which are accessible nowadays. The common computer simulation of filters in Computational Fluid Dynamic (CFD) and their effect on fluid flow pattern is done by use of permeability properties of porous media. In this research, ceramic foam filters which are used in casting are simulated by Forchhimer and Darcy models. SUT CAST software is used for simulation, because of its ability for... 

In this work, the effect of chemical composition on structural, mechanical, electrical and magnetic properties of nanocrystalline Finemet-type alloys with the composition of Fe73.5Si13.5B9Nb3Cu1 , Fe77Si11B9Nb2.4Cu0.6 and (〖Fe_0.5 Co_0.5)〗_77 Si_11 B_9 Nb_2.4 Cu_(0.6 )was investigated. The samples were prepared by vacuum arc melting of high purity constitution in order to obtain a nanocrystalline structure. The amorphous ribbons were then annealed under vacuum with the same conditions of temperatures and time to compare their properties. The structural and thermal properties of the samples were analyzed using various techniques such as X-ray Diffraction (XRD) and Differential Scanning... 

Relative permeability is an important factor that controls the two phase fluid flow in porous media. The use of carbon dioxide in enhanced oil recovery methods is common. But the question is, how does the carbon dioxide affect the relative permeability curves? In this thesis, the CO2-oil relative permeability is measured in CO2 flooding process with unsteady state method. For this purpose, the core flooding apparatus is used and the results are compared with N2-oil relative permeability in N2 flooding. The results of comparison show that oil relative permeability in CO2 flooding is higher than N2 flooding. Reduction of Interfacial tension and oil viscosity, solubility of CO2 in oil and oil... 

Porous Asphalt or Porous Friction Courses (PFCs) are mainly recommended as surface drainage layers on rainy runway pavements and roads with medium traffic. Characteristic features of porous asphalt mixes are improved permeability, skid resistance and sound attenuation. The purpose of this research is to evaluate the effect of mixture parameters such as binder content, amount of modifier and aggregate gradation on the performance and durability of the porous mixtures. In this research ground tire rubber was used as the modifier. Mechanical properties of these mixes were assessed by determining stone-on-stone condition, Marshall stability, unaged abrasion loss, and aged abrasion loss tests.... 

One of the main parameters in modeling of two phase gas and oil flow is an accurate relative permeability functions. This importance will be more intensified when the miscibility condition approaches. In miscible condition due to reduction of interfacial tension between oil and gas phases, parameters of conventional relative permeability functions will change and this changing affects on production results such as oil and gas recovery and also pressure drop along the core. All of the previous studies could not present a unique and consistent model to show the effect of near miscibility condition on relative permeability curves. In this work, these changing of parameters will be investigated... 

A considerable number of engineering applications deal with flow of fluid(s) through particulate porous media. For certain engineering problems, fluid flow may displace and even dislodge the solid particles from the mass where a fluid-particle flow occurs. The complexity of involving processes which should be studied at the scale of moving particles transforms the analyses of these problems towards a difficult engineering task. Characteristics of solid grains such as size and shape and properties of the flowing fluid(s) such as viscosity and surface tension play essential roles in the behavior of fluid-particle systems. Also, when fluid flows through porous media, secondary processes such as... 

In this project we focused on Simulation of two-phase (gas-oil) flow in 2D anisotropic porous medium on unstructured grids by finite volume method.Since the permeability assumes to be full tensor, common discretization methods for pressure and flux equations couldn’t satisfy continuity conditions then a new method of discretization named continuous flux approximation introduced.In this new method, cell center pressure calculated by directly applying flux continuity conditions to control volume boundaries. In this project a ninepoint scheme is used, it means that for making the flux continuity conditions over each control volume in two dimensions all neighboring cells are involved.The reason... 

Blending different polymers to achieve a compound with modified Physical physical and mechanical properties, has interested researchers for years. Among all, LDPE and HDPE have attracted a great attention for this purpose; specially when a mineral filler like clay is another part of composite. In the related literature, it is proven that small amounts of clay can improve physical and mechanical properties in comparison to virgin blend. Focus of this research is on HDPE/EVA/Clay nanocomposite and its physical and mechanical properties. Having vinyl group, EVA is a compatibilizer that makes clay to disperse better; EVA can also makes the brittle HDPE tougher. At first, HDPE/EVA blend... 

Because of higher hydrogen demand in recent years, study of hydrogen separation from gas mixtures is highly regarded. Because of some parameters such as high surface to volume ratio and ability to withstanding high pressure, polymeric hollow fiber membranes have a good potential of hydrogen recovery. So in this study, fabrication of single-layer and dual-layer hollow fiber membranes have been investigated. Selective polymer that used in both single and dual layer membranes is polyethersulfone. Membranes were fabricated by dry-wet phase inversion method and effects of extrusion rates and their ratio, composition and temperature of polymer solution, composition of bore fluid, coating and air... 

Circular polarization (CP) is one of the common polarization types used in wireless systems for frequency identification (RFID), global positioning (GPS) and wireless local area networks (WLAN), since it can provide greater flexibility in orientation angle between transmitter and receiver, and better mobility and weather penetration than the linearly polarized antennas. Magnetic permeability in ferrites can be tuned by external magnetic field ; So ferrites can be good candidates for new reconfigurable CP antenna technology. In this project, we will consider circularly polarized slot antenna with a wide axial ratio beamwidth that consists of a normally magnetized ferrite substrate mounted... 

Continuous approximation of pressure and flux fields is one of main goals of simulating flow in porous media. To compute the pressure field in heterogeneous and anisotropic media using minimum memory and time, it is necessary to use a conservative flux-continuous scheme. Nowadays, one of the most efficient approaches to minimize the solving time of large-scale problems is parallel computing. In this research, a parallel algorithm for flux-continuous multi-point flux approximation (MPFA) scheme with full pressure support (FPS) is designed and implemented on unstructured triangular grids by cell-centered approach. In this work, 2D single phase flows are investigated. The results are presented... 

In wireless communication systems increasing the gain of antennas is seminal to increase in coverage and data transmission rate, and reducing the possible errors. One of the main factors for improving the antenna gain is matching the polarizations of the transmitter and the receiver antennas. Towards this end, both the transmitter and the receiver antennas should have the same axial ratio, specific direction and polarizations. As far as the flexibility of the direction angle between the transmitter and the receiver is concerned, the so-called circular polarization is preferred do the linear polarization. The antennas with circular polarizations are prominently utilized in satellites,... 

Fracture and Matrix permeability systematically change because production time of gas and oil reservoirs is very long and pore pressure, temperature and in-situ stresses continously change in reservoirs.This parameters have an important role in determination and development of wells according to the permeability distribution.The main factors in determination of fracture permeability values is normal and shear stiffness that parameters such as roughness, opening, closure, aperture and asperities influence this factor.In this thesis, we try to investigate the influence of this parameters on fracture permeability according to the normal and shear stresses.Also we want to investigate the... 

In this study, simulation of two-phase water-oil compressible flow in naturally fractured reservoirs is studied. The studied reservoir has a 1D and horizontal ge-ometry that its properties such as porosity and permeability are homogeneous.Dual Porosity and Dual Porosity-Dual Permeability models are employed for simulation of reservoir. Reservoir descriptive equations are conservation of mass and momentum. Conservation of momentum equation is simplified by Darcy law and two-phase fluid flow is simulated with Black-oil model. Discretization of equations is done by finite volume method. In order to solve the equations of two-phase compressible fluid flow, the so-called IMPES (Implicit Pressure... 

Characteristic of the reservoir, including the important discussion in the oil industry, is widely practiced in the modeling, simulation and EOR. One of the methods fordetermining the specifications of the reservoir is geostatistical technique. This means that a large number of realizations of the reservoir model to assess the uncertainty in reservoir descriptions of performance predictions should be made.However flow simulation of all these realizations is very difficult due to cost and time calculations.To mend the problem, we use ranking realization that finally a minor number of realizations are selected and flow simulation is used to them.In this project, we use streamline simulation to... 

Aphron drilling fluids or CGA fluids are the wellknown updated drilling fluids in recent years.this kind of drilling fluids can control the mud loss into the formation and thus reduce formation damage and drilling costs. its structure consists of two phase fluid (gas and liquid) that the aphrons are the micro bubbles with 10 to 100 micrometer diameter that have strong stability in liquid phase compared to foamy drilling fluids. Generally aphron drilling fluids are made of base drilling fluid and surfactants, for more stability, mixed surfactant-polymer additive is so beneficial. in the last two decades, the Lattice-Boltazmann method is introduced for computational fluid dynamic area and... 

In this thesis, two types of two-phase flow are studied in one dimension. The first type is oil-gas two-phase flow which is miscible and compressible. The second one is oil-water two-phase flow which is immiscible and incompressible. Oil wet and water wet conditions are studied in the second type of flow. Two approaches, i.e. double porosity and double porosity-double permeability, are used to study naturally fractured reservoirs. In these approaches, the matrix and fracture are modeled as two separate media that exchange mass via a transfer function. Black oil model is applied to simulate the fluid system. The governing equations consist of the conservation of mass equations for each... 

Acidizing efficiency depends on various factors such as formation properties, reservoir and stimulation fluid types and injection scenario. Among these factors, heterogeneity of reservoir’s formation (layered reservoirs and permeability variation versus depth) strongly affect acidizing performance. Accordingly, applying a reliable technique that distribute stimulation fluid uniformly is essential. The aim of carbonate matrix acidizing is to improve fluid flow specially in low permeability zones. Stimulation fluid cannot enter into the low permeability layer due to existence of high permeability layers which are in contact with low permeability ones. So, the stimulation fluid should be...