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    Experimental investigation and modeling of asphaltene precipitation due to Gas Injection

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 31, Issue 1 , 2012 , Pages 89-98 ; 10219986 (ISSN) Moradi, S ; Rashtchian, D ; Ganjeh Ghazvini, M ; Emadi, M. A ; Dabir, B ; Sharif University of Technology
    Asphaltene instability is one of the major problems in gas injection projects throughout the world. Numerous models have been developed to predict asphaltene precipitation; The scaling equation is an attractive tool because of its simplicity and not involving complex properties of asphaltene. In this work, a new scaling model is presented to account for asphaltene precipitation due to gas injection at reservoir conditions. Extensive published data from literature have been used in model preparation. To check predictive capability of the equation, miscible gas injection experiments are conducted for a southwest Iranian oil reservoir. Experimental results show that methane injection has... 

    Phase morphology of polyblends of amorphous polycarbonate and semi-crystalline polyethylene terephthalate

    , Article Iranian Polymer Journal (English Edition) ; Volume 11, Issue 3 , 2002 , Pages 151-157+209 ; 10261265 (ISSN) Frounchi, M ; Mehrabzadeh, M ; Mohseni, S. S ; Sharif University of Technology
    Phase morphology, state of compatibility and various properties of blends of polycarbonate (PC) with bottle-grade and fibre-grade polyethylene terephthalate (BPET and FPET, respectively) were investigated. It was found that these blends have two-phase separated morphology with partial miscibility. Scanning electron micrographs revealed separated domains of PC-rich and PET-rich zones. PC domains appear spherical increasing in size from 2 μm for PC20/FPET80 up to about 5 μm for PC60/FPET40 blend. Further increase in PC content up to 80% caused phase inversion in which FPET appears as finely dispersed domains in continuous PC matrix. Tg of PC-rich phase decreased from 153 deg;C for pure PC down... 

    Micro-model experimental study of fracture geometrical effect on breakthrough time in miscible displacement process

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 3 , 2011 , Pages 1-7 ; 10219986 (ISSN) Kamari, E ; Rashtchian, D ; Shadizadeh, S. R ; Sharif University of Technology
    The miscible displacement process appears to be an increasingly feasible method for the extraction of oil from depleted reservoirs. However, there is a lack of fundamental understanding of how fracture geometrical characteristics impact the oil recovery efficiency in this type of enhanced oil recovery technique. In this work, a series of experimental tests were conducted whereby the n-Heptane as a solvent displaced n-Decane in the glass micro-models having different fracture geometries. It has been observed that the breakthrough time is decreased with increasing the fractures' length. In contrast, breakthrough time is increased when increasing the fractures orientation angle related to flow... 

    Investigation of the minimum miscibility pressure for injection of two different gases into two Iranian oil reservoirs: experimental and theory

    , Article Canadian Journal of Chemical Engineering ; Volume 95, Issue 5 , 2017 , Pages 1014-1020 ; 00084034 (ISSN) Moosazadeh, M ; Keshavarzi, B ; Ghotbi, C ; Sharif University of Technology
    Wiley-Liss Inc  2017
    The results of the minimum miscibility pressure (MMP) determination for miscible injection of CO2 and an associated gas of one of Iranian gas reservoirs into two different oil samples using a slim tube device are presented. For an effective determination of the MMP cell-to-cell slim tube simulation was performed for each case before performing the slim tube experiment and the results were used to determine the pressure intervals in the slim tube experiment. A comparison between the measured MMP values from the slim tube experiments and those calculated by cell-to-cell simulation revealed that the cell-to-cell simulation can be a substitute to slim tube test in cases where time is a primary... 

    Monitoring and characterizing the finger patterns developed by miscible displacement in fractured heavy oil systems

    , Article Industrial and Engineering Chemistry Research ; Volume 52, Issue 31 , July , 2013 , Pages 10853-10863 ; 08885885 (ISSN) Shokrollahi, A ; Majidi, S. M. J ; Ghazanfari, M. H ; Sharif University of Technology
    This work concerns experimentally quantifying finger behavior during miscible displacements in fractured porous media. A series of miscible tests were performed on five-spot fractured micromodels which were initially saturated with heavy crude oil, and the developed finger patterns were quantified using an image analysis technique. The results revealed that the numbers of macro fingers formed is well correlated with the square root of dimensionless time, while the rate of finger initiation is independent of fracture characteristics. The level of bypassed oil linearly decreases with dimensionless distance traveled by front precisely. The transient fractal dimension behavior experiences a... 

    Improvement of fractional flow model for miscible displacement process: An experimental investigation in single fractured porous medium

    , Article Journal of Porous Media ; Volume 16, Issue 3 , 2013 , Pages 255-266 ; 1091028X (ISSN) Kamari, E ; Shadizadeh, S. R ; Rashtchian, D ; Sharif University of Technology
    Most of the reservoirs in Iran are heterogeneous fractured carbonate reservoirs. Heterogeneity causes an earlier breakthrough and an unstable front, which leads to a lower recovery. In this study, a series of experiments was conducted whereby the n-Heptane displaced n-Decane in glass micromodels having different fracture geometries. Experimental data from image analysis of miscible displacement processes are used to modify the fractional flow equations by a heterogeneity factor. It is shown that the heterogeneity factor in the modified equations can be expressed as a function of fracture length and orientation  

    Evaluation of Different Water and Gas Injection Scenarios for Improving Recovery of One of the Iranian South West Reservoirs

    , M.Sc. Thesis Sharif University of Technology Fallah Tafty, Mona (Author) ; Masihi, Mohsen (Supervisor)
    Increasing the global demand for energy and decreasing the production rate of oil reservoirs have forced the oil companies to focus on enhanced oil recovery (EOR) extensively. This paper summarizes the design, reservoir simulation, and results of different gas injection scenarios in one of the Iranian complex oil reservoirs. This complex reservoir is located in the south west of Iran and is made up of sandstone, limestone, and dolomite layers. It is an under saturated reservoir with no gas cap but with a strong aquifer. Oil production has started in 1977, but due to strong aquifer the production is still in the plateau period. In this study, by simulation, it is estimated that natural... 

    Experimental and Simulation Studies of Oil Recovery Via Immiscible and Near Miscible Simultaneous Water and CO2 Injection in an Iranian Reservoir

    , M.Sc. Thesis Sharif University of Technology Seyyedsar, Mehdi (Author) ; Taghikhani, Vahid (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor)
    A simultaneous water and CO2 injection study using sandstone cores with 21°API Sarvak (Azadegan field) oil has performed to evaluate oil recovery under four injection modes: secondary immiscible, secondary near-miscible, tertiary immiscible, and tertiary near-miscible. It is demonstrated that swag injection (secondary and tertiary) is an effective method for the recovery of significant amount of oil or residual oil from water-flooded porous media, but there is always some bypassing (at the pore level) of the oil due to topological effects, water-shielding and dead-end pores. In non-homogeneous porous medium, oil recovery is depending to SWAG ratio in immiscible and near-miscible conditions.... 

    Experimental study of asphaltene precipitation behavior during miscible carbon dioxide injection

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 14 , July , 2014 , pp. 1523-1530 ; ISSN: 15567036 Alizadeh, A ; Nakhli, H ; Kharrat, R ; Ghazanfari, M. H ; Aghajani, M ; Sharif University of Technology
    Many reservoir and production engineers face asphaltene precipitation as a major problem during miscible carbon dioxide flooding projects. Experimental studies regarding asphaltene precipitation are therefore employed to assist in selecting appropriate facilities and proper operation schemes. During this study, a series of high pressure, high temperature experiments are designed and performed to analyze asphaltene precipitation behavior of an Iranian light reservoir crude at reservoir conditions due to natural production and miscible CO2 gas injection. For both sets of experiments, two different temperature levels (including reservoir temperature) are selected to investigate the role of... 

    Intelligent model for prediction of CO2 - Reservoir oil minimum miscibility pressure

    , Article Fuel ; Volume 112 , 2013 , Pages 375-384 ; 00162361 (ISSN) Shokrollahi, A ; Arabloo, M ; Gharagheizi, F ; Mohammadi, A. H ; Sharif University of Technology
    Multiple contact miscible floods such as injection of relatively inexpensive gases into oil reservoirs are considered as well-established enhanced oil recovery (EOR) techniques for conventional reservoirs. A fundamental factor in the design of gas injection project is the minimum miscibility pressure (MMP), whereas local sweep efficiency from gas injection is very much dependent on the MMP. Slim tube displacements, and rising bubble apparatus (RBA) are two main tests that are used for experimentally determination of MMP but these tests are both costly and time consuming. Hence, searching for quick and accurate mathematical determination of gas-oil MMP is inevitable. The objective of this... 

    On the determination of CO2-crude oil minimum miscibility pressure using genetic programming combined with constrained multivariable search methods

    , Article Fuel ; Volume 173 , 2016 , Pages 180-188 ; 00162361 (ISSN) Fathinasab, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier Ltd 
    In addition to reducing carbon dioxide (CO2) emission, the high oil recovery efficiency achieved by CO2 injection processes makes CO2 injection a desirable enhance oil recovery (EOR) technique. Minimum miscibility pressure (MMP) is an important parameter in successful designation of any miscible gas injection process such as CO2 flooding; therefore, its accurate determination is of great importance. The current experimental techniques for determining MMP are expensive and time-consuming. In this study, multi-gene genetic programming has been combined with constrained multivariable search methods, and a simple empirical model has been developed which provides a reliable estimation of MMP in a... 

    Oil-Gas MMP Determination in Enhanced Oil Recovery Methods by Experimental Method of Vanishing Interfacial Tension

    , M.Sc. Thesis Sharif University of Technology Fathinasab, Mohammad (Author) ; Taghikhani, Vahid (Supervisor) ; Ayatollahi, Shahabodin (Supervisor)
    Minimum miscibility pressure (MMP) is a key parameter for successful gas injection process in the oil reservoirs for more oil recovery. This parameter is critically dependent on the reservoir condition such as temperature, reservoir and injection gas composition. There are many techniques used in the literature for MMP measurement. Vanishing interfacial tension (VIT) has been proposed recently and was used successfully to predict the MMP through pendant drop technique. This technique is used in this study to measure the MMP for Nitrogen/Carbon dioxide and water in oil emulsion fluids; then compare it to the original crude oil without water droplets. This would demonstrate the effects of... 

    Empirical Study of Minimum Miscibility Pressure Determination of CO2 and Associate Gas in Iranian Off-shore Oil

    , M.Sc. Thesis Sharif University of Technology Esmaeili Rad, Farnaz (Author) ; Tghikhani, Vahid (Supervisor) ; Ghotbi, Cyrus (Supervisor) ; Badakhshan, Amir (Supervisor)
    The main EOR method after heat recovery is gas injection. Minimum miscibility pressure is one of the parameters that affect gas injection. This project includes computational and laboratory sections to estimate the MMP. The MMP were estimated during the injection of CO2, Ga, Gb and methane gases into two oil samples. In the computational part of the project, MMP is estimated through cell to cell simulation and using Peng_Robinson equation of state. Also, the MMP is measured by using slim tube apparatus which is used so widely in the industry. According to the results, CO2 has the lowest miscibility pressure among other gases. It was miscible into oil even at pressures near the bubble... 

    Investigation the Minimum Miscibility Pressure for Crude oil with Different Asphaltene Content using Vanishing Interfacial Tension Method

    , M.Sc. Thesis Sharif University of Technology Hemmati-Sarapardeh, Abdolhossein (Author) ; Ayatollahi, Shahab (Supervisor) ; Masihi, Mohsen (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor)
    Interfacial Tension (IFT) as a main parameter for gas flooding efficiency in oil reservoirs depends highly on pressure, temperature, and composition of the reservoir fluids. Therefore, it is important to measure this parameter at real reservoir condition for successful field development plan. In this study, an axisymmetric drop shape analysis (ADSA) has been utilized to measure the equilibrium IFTs in crude oil-CO2 as well as crude oil-N2 systems at different temperatures and pressures. Moreover, minimum miscibility pressures (MMP) and first-contact miscibility pressures (Pmax) of crude oil/CO2 and crude oil/N2 systems at different temperature levels are determined by applying vanishing... 

    Modeling and Simulation of Miscible Flow through Fractured Porous Media Using Random Walk Method

    , M.Sc. Thesis Sharif University of Technology Fayazi, Amir (Author) ; Ghazanfari, Mohammad Hossein (Supervisor)
    Miscible displacement in fluid flowing through a porous medium plays an important role in many environmental and industrial applications; for instance, miscible displacements in enhanced oil recovery processes and pollutant spreading in groundwater. A large number of numerical approaches have been developed to solve the advection-dispersion equation that describes the behavior of miscible displacement in porous media. Most of these numerical models suffer from numerical dispersion. Random walk seems to be an effective method to overcome this problem especially in heterogeneous media. Here, a random walk model was developed and used for simulating miscible displacement in heterogeneous porous... 

    Pore Scale Experimental Investigation of Increasing the Efficiency of EOR Methods in Heavy Oil Fractured Reservoirs Using Ultrasonic Wave Technology

    , M.Sc. Thesis Sharif University of Technology Seydi, Mahdi (Author) ; Ghotbi, Siroos (Supervisor) ; Ghazanfar, Mohammad Hossein (Co-Advisor) ; Taghikhani, Vahid (Co-Advisor)
    Nowadays, application of ultrasonic wave technology as a novel method of enhancing oil recovery and also gas and oil well stimulation is prevailing. Not only this method is environment friendly, but also it is economic. Although the application of this method is proved to be of outstanding positive influences in field operations. In this study, it is intended to investigate the effect of ultrasonic waves on the rate and final recovery of miscible and immiscible injection of fluids as Enhanced Oil Recovery (EOR) methods by using the Micro model apparatus and Although the effect of the waves on fluid flow through the porous media can be studied. The results of this work are a good guidance to... 

    PLA/PVAc Nano-Blends for Barrier Films: Effect of Gamma Irradiation

    , M.Sc. Thesis Sharif University of Technology Razavi, Mohammad (Author) ; Forounchi, Massoud (Supervisor) ; Dadbin, Susan (Supervisor)
    Oxygen barrier properties of poly (lactic acid) (PLA) films were improved by blending it with hydrolyzed poly (vinyl acetate). Poly (vinyl acetate-co-vinyl alcohol) with vinyl alcohol contents of 0, 5, 10 and 15% was prepared using acid-catalyzed hydrolysis of poly (vinyl acetate). The Blend films of PLA/poly (VAc-co-VA) containing 0, 5, 10 and 15% of the copolymer with various degree of hydrolysis was prepared by solution-casting method. Effect of gamma irradiation on the films was examined by exposing them to radiation doses of 0, 20, 35 and 50 kGy. The films remained colorless and transparent after irradiation. Morphology of the samples characterized by optical microscopy displayed not... 

    Random walk simulation of miscible flow through heterogeneous 2D porous media considering dispersion tensor

    , Article Chemical Engineering Science ; Volume 132 , August , 2015 , Pages 81-92 ; 00092509 (ISSN) Fayazi, A ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier Ltd  2015
    Most of numerical approaches describing the behavior of miscible displacement in porous media through the solution of advection-dispersion equation suffer from numerical dispersion. Random Walk (RW) method is a good candidate to overcome this problem especially in heterogeneous media. In addition, how treating dispersion coefficient as a tensor might affect the accuracy of RW simulation results is not well understood. Here, a RW model was developed and used for simulating miscible displacement experiments performed on heterogeneous micromodels including single fracture/flow barrier. Dispersion coefficient was treated as a tensor and a hybrid scheme was used for velocity interpolation. The... 

    Determination of minimum miscibility pressure in N2–crude oil system: A robust compositional model

    , Article Fuel ; Volume 182 , 2016 , Pages 402-410 ; 00162361 (ISSN) Hemmati Sarapardeh, A ; Mohagheghian, E ; Fathinasab, M ; Mohammadi, A. H ; Sharif University of Technology
    Elsevier Ltd 
    Nitrogen has been valued as an economical alternative injection gas for gas-based enhanced oil recovery (EOR) processes. Minimum miscibility pressure (MMP) is the most important parameter to successfully design N2 flooding. In this communication, a data bank covering wide ranges of thermodynamic and compositional conditions was gathered from open literature. Afterward, a rigorous approach, namely least square support vector machine (LSSVM) optimized with coupled simulated annealing (CSA) was proposed to develop a reliable and robust model for the prediction of MMP of pure/impure N2–crude oil. The results of this study showed that the proposed model is more reliable and accurate than the... 

    Gas-oil relative permeability at near miscible conditions: an experimental and modeling approach

    , Article Scientia Iranica ; Volume 20, Issue 3 , 2013 , Pages 626-636 ; 10263098 (ISSN) Parvazdavani, M ; Masihi, M ; Ghazanfari, M. H ; Sharif University of Technology
    Reliable relative permeability curves of oil-gas systems are important for successful simulation and modeling of gas injection, especially when the miscibility condition approaches. In this work, the relative permeability of a CO2-light oil system has been measured under different conditions, using the Civan and Donaldson (1989) [13] method. Dolomite and sandstone core samples were used in the experiments. The minimum miscibility pressure was calculated using an empirical correlation, as well as slim-tube simulation. Due to some controversial assumptions of the Civan and Donaldson method, such as immiscible and incompressible displacement, history matching was used for predicting the...