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    Phase behavior and interfacial tension evaluation of a newly designed surfactant on heavy oil displacement efficiency; effects of salinity, wettability, and capillary pressure

    , Article Fluid Phase Equilibria ; Vol. 396, issue , June , 2015 , p. 20-27 ; ISSN: 03783812 Dehghan, A. A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    This work aims to discuss the results of wide ranges of laboratory investigations to evaluate the performance of a newly-formulated surfactant for heavy oil reservoirs in order to improve the microscopic sweep efficiency after water flooding processes. In the first part, the specific behavior of the formulated surfactant including its salinity tolerance, interfacial tension, and optimum performance window was determined. Then, the application of surfactant solutions in real sandstone reservoir rocks was assessed for both oil-wet and water-wet cases. Besides, the effect of changing the capillary and viscous forces and interfacial tension on the residual phase saturations were characterized.... 

    Interfacial tension and wettability change phenomena during alkali-surfactant interactions with acidic heavy crude oil

    , Article Energy and Fuels ; Vol. 29, issue. 2 , January , 2015 , p. 649-658 ; ISSN: 08870624 Dehghan, A. A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    In this work, a newly formulated sulfonate-based surfactant and two other commercial sulfate-based surfactants with the capability of tolerating harsh underground reservoir conditions, such as high-saline formation water and high temperature, were prepared. Sodium metaborate as an effective alkali compound was also used to provide alkali-surfactant combination. Interfacial tension (IFT) measurements as well as wettability examinations for different salinities and mixture conditions were performed for an extended range of the chemical concentrations. The wettability tests including both contact angle measurements and Amott cell tests were performed on saturated Berea sandstone plug samples... 

    Studying the Mechanistic Behavior of Heavy Oil Displacement Using a Group of Alkalis and Surfactant Mixtures

    , Article Chemical Engineering Communications ; Vol. 202, issue. 3 , May , 2015 , p. 366-374 ; ISSN: 00986445 Dehghan, A. A ; Jadaly, A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    In this study, a mixture-based sulfonate-based surfactant with a novel formula capable of functioning in real oil reservoir conditions was prepared and some microscopic parameters, like its compatibility state, emulsion behavior, interfacial tension, and temperature dependency in the presence of a heavy oil sample, and two of the most popular alkalis were analyzed; then the results were compared with those of a commercial sulfate-based surfactant. The designed surfactant provided an optimum three-phase region in relatively high salinity media; however, its optimum value decreased when adding any alkaline materials; this trend was reversed for the solutions made with the sulfate-based... 

    Monitoring the effect of discontinuous shales on the surfactant flooding performance in heavy oil reservoirs using 2D glass micromodels

    , Article Petroleum Science and Technology ; Vol. 32, issue. 12 , Apr , 2014 , p. 1404-1417 ; ISSN: 10916466 Mohammadi, S ; Kharrat, R ; Masihi, M ; Ghazanfari, M. H ; Saidian, M ; Sharif University of Technology
    Although most heavy oil reservoirs contain discontinuous shaly structures, there is a lack of fundamental understanding how the shaly structures affect the oil recovery efficiency, especially during surfactant flooding to heavy oils. Here, an experimental study was conducted to examine the effect of discontinuous shales on performance of surfactant flooding by introducing heterogeneities to represent streaks of shale in five-spot glass micromodels. Results show that oil recovery in presence of shale streak is lower than in its absence. Based on the authors' observations, the presence of flow barriers causes premature breakthrough of injected fluids and also an unstable displacement front. As... 

    Evaluation of chemicals interaction with heavy crude oil through water/oil emulsion and interfacial tension study

    , Article Energy and Fuels ; Vol. 27, issue. 10 , September , 2013 , p. 5852-5860 ; ISSN: 08870624 Dehghan, A. A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    A newly-designed surfactant was formulated to tolerate the harsh conditions of oil reservoirs, including high salinity of the formation brine and temperature. The specific emulsion and interfacial tension (IFT) behavior of this new surface active agent were investigated by performing emulsion stability tests, emulsion size analysis, and IFT behavior in the presence of four different types of alkalis. Image processing was utilized to analyze the droplet size distribution using microscopic images of the samples. The results show that depending on the composition of the mixtures, the optimum phase region and interfacial tension behavior change considerably. Solutions containing a higher... 

    Bubble in flow field: A new experimental protocol for investigating dynamic adsorption layers by using capillary pressure tensiometry

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 460, issue , 2014 , p. 369-376 Lotfi, M ; Bastani, D ; Ulaganathan, V ; Miller, R ; Javadi, A ; Sharif University of Technology
    For many years the model of a dynamic adsorption layer (DAL) is well established as explanation for the behavior of rising bubbles in surfactant solutions. This model explains the velocity profile and the evolution of the shape of a rising bubble based on the hypothesis of the balance between the drag force and the structure of the adsorbed layer governed by Marangoni convection. However, direct measurements of interfacial properties of the bubble during rising are a real challenge. Here we present a new experimental protocol called "bubble in flow field" suitable for direct measurements of dynamic interfacial properties of a bubble surface using the capillary pressure tensiometry under... 

    Spotlight on kinetic and equilibrium adsorption of a new surfactant onto sandstone minerals: A comparative study

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 50 , May , 2015 , Pages 12-23 ; ISSN: 18761070 Arabloo, M ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
    This paper presents a state of the art review of adsorption models for a new plant-based surfactant adsorption onto sandstone minerals. The adsorption data at both kinetic and equilibrium modes were obtained from batch experiments. Four adsorption kinetic models, five two-parameter, and six three-parameter equilibrium models were used for interpretation of the obtained data. Among the two and three-parameter isotherm models applied, the Jovanovic and the Khan isotherms showed the best fit, respectively. And the pseudo-second order model presented a better fit than other kinetic models. Finally, a computer-based modeling approach was developed and used for predicting the kinetics of... 

    Numerical simulation of surfactant flooding in darcy scale flow

    , Article Petroleum Science and Technology ; Vol. 32, Issue. 11 , 2014 , Pages 1365-1374 ; ISSN: 10916466 Morshedi, S ; Foroughi, S ; Beiranvand, M. S ; Sharif University of Technology
    One of the methods that is used nowadays in enhanced oil recovery is surfactant flooding. The main mechanisms of surfactant flooding in reservoir consist of reduction of interfacial tension between water and oil and modification of rock wettability. In this study, the authors simulate the surfactant injection process in Darcy scale and in one-dimensional, multicomponent, multiphase state, and effects of physical phenomena such as adsorption, dispersion, convection, and exchange between fluids and solids are considered. Wettability alteration of reservoir rock due to presence of surfactant in injected fluid is detected in relative permeability and capillary pressure curves. First, the authors... 

    Modification of rock/fluid and fluid/fluid interfaces during MEOR processes, using two biosurfactant producing strains of Bacillus stearothermophilus SUCPM#14 and Enterobacter cloacae: A mechanistic study

    , Article Colloids and Surfaces B: Biointerfaces ; Vol. 117 , May , 2014 , pp. 457-465 ; ISSN: 09277765 Sarafzadeh, P ; Zeinolabedini Hezave, A ; Mohammadi, S ; Niazi, A ; Ayatollahi, S ; Sharif University of Technology
    During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding... 

    A novel approach for preparation of CL-20 nanoparticles by microemulsion method

    , Article Journal of Molecular Liquids ; Vol. 193, issue , May , 2014 , pp. 83-86 Bayat, Y ; Zarandi, M ; Zarei, M. A ; Soleyman, R ; Zeynali, V ; Sharif University of Technology
    2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) as one of the high energy cage nitramines has been used in various propellants and explosive formulations. The performance of energetic materials depends on its particle size and shape. Therefore, in this research, microemulsion method has been applied for the preparation of CL-20 nanoparticles via oil in water (O/W) microemulsions. The optimized formulation contains water 45%, n-butyl acetate 20.5%, sodium dodecyl sulfate (SDS, as anionic surfactant) 6.5% and 2-propanol (as co-surfactant) 26.5%. CL-20 nanoparticles that were obtained by microemulsion method are spherical with an average diameter of 25 nm, based on TEM image.... 

    Marangoni instabilities for convective mobile interfaces during drop exchange: Experimental study and CFD simulation

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 441, issue , 2014 , pp. 846-854 ; ISSN: 09277757 Javadi, A ; Karbaschi, M ; Bastani, D ; Ferri, J. K ; Kovalchuk, V. I ; Kovalchuk, N. M ; Javadi, K ; Miller, R ; Sharif University of Technology
    The inflow pattern of liquid into a droplet is studied experimentally using a surface active dye and compared with results of CFD simulations. The results show visual agreement between experiments and simulations. The CFD simulations show also good agreement with the surface tension measured by drop profile analysis tensiometry (PAT). The inflow of the surfactant induces a Marangoni instability caused by the local arrival of the surfactant at the drop surface. The onset of this Marangoni instability observed experimentally has a delay of about 10. s when compared with the simulation results. Different scenarios are discussed, including a boundary layer barrier, a kinetic-controlled... 

    Investigating the efficiency of MEOR processes using Enterobacter cloacae and Bacillus stearothermophilus SUCPM#14 (biosurfactant-producing strains) in carbonated reservoirs

    , Article Journal of Petroleum Science and Engineering ; Volume 113 , January , 2014 , Pages 46-53 ; ISSN: 09204105 Sarafzadeh, P ; Niazi, A ; Oboodi, V ; Ravanbakhsh, M ; Hezave, A. Z ; Ayatollahi, S ; Raeissi, S ; Sharif University of Technology
    Microbial enhanced oil recovery (MEOR) process is divided into two main categories, namely in-situ and ex-situ techniques. It utilizes reservoir microorganisms or specially selected bacteria to use their metabolites for more oil recovery from depleted oil reservoirs. In the present study, the potential of two biosurfactant-producing strains of Enterobacter cloacae and Bacillus stearothermophilus SUCPM#14 were investigated on tertiary oil recovery efficiency in carbonated cores using different designed injection protocols. The required operational time, process cost and proper selection of bacterial formulation during the MEOR process were the main objectives of this study. The results of... 

    Investigation of wettability alteration through relative permeability measurement during MEOR process: A micromodel study

    , Article Journal of Petroleum Science and Engineering ; Vol. 120, issue , 2014 , p. 10-17 Khajepour, H ; Mahmoodi, M ; Biria, D ; Ayatollahi, S ; Sharif University of Technology
    Microbial Enhanced Oil Recovery (MEOR) as a tertiary process employs microorganisms and their metabolites to reduce the residual oil saturation of the reservoir mainly through interfacial tension (IFT) reduction and wettability alteration. In spite of its great potential and the mentioned advantages, application of MEOR has been limited because of the lack of practical convincing experimental results. In this study, the effects of MEOR process on wettability changes and the reduction of residual oil saturation have been examined by providing microscopic visualization of two phase flow in transparent glass micromodels. Biosurfactant producing bacterial strain (Enterobacter cloacae) was... 

    Statistical screening of medium components for recombinant production of Pseudomonas aeruginosa ATCC 9027 rhamnolipids by nonpathogenic cell factory pseudomonas putida KT2440

    , Article Molecular Biotechnology ; Vol. 56, issue. 2 , 2014 , p. 175-191 Setoodeh, P ; Jahanmiri, A ; Eslamloueyan, R ; Niazi, A ; Ayatollahi, S. S ; Aram, F ; Mahmoodi, M ; Hortamani, A ; Sharif University of Technology
    Rhamnolipids (RLs) produced by the opportunistic human pathogen Pseudomonas aeruginosa are considered as potential candidates for the next generation of surfactants. Large-scale production of RLs depends on progress in strain engineering, medium design, operating strategies, and purification procedures. In this work, the rhlAB genes extracted from a mono-RLs-producing strain of P. aeruginosa (ATCC 9027) were introduced to an appropriate safety host Pseudomonas putida KT2440. The capability of the recombinant strain was evaluated in various media. As a prerequisite for optimal medium design, a set of 32 experiments was performed in two steps for screening a number of macro-nutritional... 

    Prediction of Surfactant Retention in Porous Media: A Robust Modeling Approach

    , Article Journal of Dispersion Science and Technology ; Vol. 35, issue. 10 , Sep , 2014 , p. 1407-1418 Yassin, M. R ; Arabloo, M ; Shokrollahi, A ; Mohammadi, A. H ; Sharif University of Technology
    Demands for hydrocarbon production have been increasing in recent decades. As a tertiary production processes, chemical flooding is one of the effective technologies to increase oil recovery of hydrocarbon reservoirs. Retention of surfactants is one of the key parameters affecting the performance and economy of a chemical flooding process. The main parameters contribute to surfactant retention are mineralogy of rock, surfactant structure, pH, salinity, acidity of the oil, microemulsion viscosity, co-solvent concentration, and mobility. Despite various theoretical studies carried out so far, a comprehensive and reliable predictive model for surfactant retention is still found lacking. In this... 

    The impact of surfactants on wettability change and level of water imbibition in relation to EOR in carbonate reservoirs

    , Article Petroleum Science and Technology ; Volume 31, Issue 20 , 2013 , Pages 2098-2109 ; 10916466 (ISSN) Zangeneh Var, A ; Bastani, D ; Badakhshan, A ; Sharif University of Technology

    An experimental investigation of surfactant flooding as a good candidate for enhancing oil recovery from fractured reservoirs using one-quarter five spot micromodels: The role of fracture geometrical properties

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 35, Issue 20 , 2013 , Pages 1929-1938 ; 15567036 (ISSN) Kianinejad, A ; Ghazanfari, M. H ; Kharrat, R ; Rashtchian, D ; Sharif University of Technology
    Surfactant flooding is known to lower the interfacial tension and, hence, reduces capillary forces responsible for trapping oil. Despite numerous experimental studies, little is known about the role of fracture geometrical properties on oil recovery efficiency during surfactant floods, especially in five-spot systems. In addition, application of sodium dodecyl sulfate for oil recovery in fractured media is not discussed well. In this study, two types of surfactant solutions have been injected into micromodels, which were initially saturated with crude oil, having different length, orientation, and distribution of fractures under oil-wet conditions. Precise analyses of continuously recorded... 

    Controlled growth of hollow polyaniline structures: From nanotubes to microspheres

    , Article Polymer (United Kingdom) ; Volume 54, Issue 21 , 2013 , Pages 5586-5594 ; 00323861 (ISSN) Pirhady Tavandashti, N ; Ghorbani, M ; Shojaei, A ; Sharif University of Technology
    Homogeneous and fairly monosized microspherical structures of polyaniline has been synthesized using a simple soft template method with β-naphthalene sulfonic acid (β-NSA) as both the surfactant and dopant, and ammonium persulfate (APS) as the oxidant at 2-5 C. The morphology of PANI-NSA was successfully controlled from nanotubes to microsphere, by changing the synthesis conditions (i.e. pH, the concentration of surfactant and monomer, and temperature). Some mechanistic aspects of the formation of nanotubes and hollow spheres have been discussed precisely based on SEM, TEM, DLS, FTIR and UV-visible results. Moreover, synthesis was performed under acidic environment to obtain further... 

    Highly efficient hydroxyapatite/TiO2 composites covered by silver halides as E. coli disinfectant under visible light and dark media

    , Article Photochemical and Photobiological Sciences ; Volume 12, Issue 10 , 2013 , Pages 1787-1794 ; 1474905X (ISSN) Azimzadehirani, M ; Elahifard, M ; Haghighi, S ; Gholami, M ; Sharif University of Technology
    TiO2-based photocatalysts are seen as the most common agents for the photodegradation of bacteria. In this study, AgCl/TiO2, hydroxyapatite(Hp)/AgCl/TiO2, AgI/TiO2, and Hp/AgI/TiO2 were prepared by the deposition-precipitation method on P25 TiO2 nanoparticles and were characterized by XRD, SEM, FT-IR, EDX and BET methods. The prepared composites showed high efficiency for the inactivation of Escherichia coli (E. coli) bacteria under visible light and in dark media with different catalyst amounts of 12 and 24 mg, respectively. In less than 30 min, AgI/TiO2, prepared by the combination of cationic surfactant and PVPI2, disinfected 1 × 107 colony-forming units of E. coli completely. However,... 

    Thermal conductivity of mixed nanofluids under controlled pH conditions

    , Article International Journal of Thermal Sciences ; Volume 74 , 2013 , Pages 63-71 ; 12900729 (ISSN) Iranidokht, V ; Hamian, S ; Mohammadi, N ; Shafii, M. B ; Sharif University of Technology
    Just a few investigations have been conducted to study the mixed nanofluids(MNs), which contain more than one type of nanoparticles, despite considerable advances in the field of nanofluids thermal conductivity. In present research, by combining different volume fractions of various nanoparticles, the variation of mixed nanofluids thermal conductivity was considered. The mentioned nanofluids have different fabrication cost. First, the effect of each specific nanoparticle presence in the base fluid on the thermal conductivity of nanofluid was surveyed both experimentally and theoretically. Then, the thermal conductivities of two MNs, one consisted of a metallic nanoparticle (high thermal...