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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
    Abstract
    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
    Abstract
    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... 

    Monitoring the influence of dispersed nano-particles on oil-water relative permeability hysteresis

    , Article Journal of Petroleum Science and Engineering ; Vol. 124, issue , December , 2014 , p. 222-231 ; ISSN: 09204105 Parvazdavani, M ; Masihi, M ; Ghazanfari, M. H ; Sharif University of Technology
    Abstract
    In recent years, polysilicon nanoparticles are used to enhance the oil recovery through the water injection process in oilfields. The contributing mechanisms are the reduction of interfacial tension and wettability alteration which lead to improving or decreasing the oil phase relative permeability and can be traced by change of relative permeability curves. However, profound understanding of the effect of dispersed nano-silica particles on the hysteretic behavior of relative permeability curves remains a controversy topic in the literature.The current study illustrates the influence of dispersed silica particles on hysteretic trend of two-phase curves of oil-water relative permeability.... 

    Effect of time and temperature on crude oil aging to do a right surfactant flooding with a new approach

    , Article Proceedings of the Annual Offshore Technology Conference ; Vol. 2, issue , 2014 , p. 1136-1142 ; ISSN: 01603663 ; ISBN: 9781632663870 Heidari, M. A ; Habibi, A ; Ayatollahi, S ; Masihi, M ; Ashoorian, S ; Sharif University of Technology
    Abstract
    Dilute Surfactant flooding has been recognized as one of the significant processes in chemical flooding. Many oil reservoirs became appropriate candidates for surfactant/water flooding when screening criteria was developed. Injected surfactant tried to mobilize the residual oil that was trapped in interstice. The main contributing mechanism to enhance oil recovery by surfactant flooding was defined as rock wettability alteration. Wettability is one of the substantial parameters to choose the best approach for a successful surfactant flooding in which tiny change in wettability will lead to improve oil recovery fundamentally. In this experimental study the effect of different aging time and... 

    Index for characterizing wettability of reservoir rocks based on spontaneous imbibition recovery data

    , Article Energy and Fuels ; Vol. 27, issue. 12 , November , 2013 , p. 7360-7368 ; ISSN: 08870624 Mirzaei-Paiaman, A ; Masihi, M ; Standnes, D. C ; Sharif University of Technology
    Abstract
    An index for characterizing wettability of reservoir rocks is presented using slope analysis of spontaneous imbibition recovery data. The slope analysis is performed using the known exact analytical solution to infinite acting period of counter-current spontaneous imbibition. The proposed theoretically based wettability index offers some advantages over existing methods: (1) it is a better measure of the spontaneous imbibition potential of rock (because the magnitude is directly proportional to the imbibition rate); (2) there is no need for forced displacement data; (3) there is no need for waiting until the spontaneous imbibition process ceases completely; and (4) the data needed to run the... 

    Investigation of the effect of water based nano-particles addition on hysteresis of oil and-water relative permeability curves

    , Article Society of Petroleum Engineers - SPE International Oilfield Nanotechnology Conference 2012 ; June , 2012 , p. 267-277 Parvazdavani, M ; Masihi, M ; Ghazanfari, M. H ; Sherafati, M ; Mashayekhi, L ; Sharif University of Technology
    Abstract
    It has been shown that one kind of poly silicon particles with sizes ranging from 10-500 nm, can be used in oilfields to enhance the oil recovery of water injection by 15-20%. The contributing mechanism might be reducing the interfacial tension which appears through improving relative permeability of the oil-phase. However, fundamental understanding of how hysteretic behavior of relative permeability curves affected by nanosilica particles remains a topic of debate in the literature. In this study, water as well as water dispersed nanosilica particles floods was performed on sandstone rock sample saturated by light crude oil supplied from one of Iranian oil reservoir, and the relative... 

    The impacts of aqueous ions on interfacial tension and wettability of an asphaltenic-acidic crude oil reservoir during smart water injection

    , Article Journal of Chemical and Engineering Data ; Vol. 59, issue. 11 , 2014 , pp. 3624-3634 ; ISSN: 00219568 Lashkarbolooki, M ; Ayatollahi, S ; Riazi, M ; Sharif University of Technology
    Abstract
    The use of adjusted/optimized saline water categorized into two different classes namely smart water (SW) and low salinity (LoSal) water injection has been proposed for more oil recovery from specific types of oil reservoirs. There are possible mechanisms concerning SW flooding that have been proposed in the literature, some of them are still subject to more examination. In this study, an experimental investigation is performed to determine the influence of type and amount of salt to the surface properties including interfacial tension (IFT) and contact angle (CA) of aqueous solution + acidic and asphaltenic crude oil + carbonate rock systems. For this purpose, the concentration of different... 

    Investigation of the microscopic displacement mechanisms and macroscopic behavior of alkaline flooding at different wettability conditions in shaly glass micromodels

    , Article Journal of Petroleum Science and Engineering ; Vol. 122, issue , August , 2014 , pp. 595-615 ; ISSN: 09204105 Mehranfar, A ; Ghazanfari, M. H ; Sharif University of Technology
    Abstract
    Among various chemical methods, alkaline flooding has a great potential for enhancing heavy oil recovery, especially for reservoirs which contain acidic crude oil. However, fundamental understanding about microscopic displacement mechanisms and macroscopic behavior during alkaline floods at different wettabilities is not well understood, especially in five-spot shaly models. In this work several alkaline floods are performed on a glass micromodel containing randomly distributed shale streaks at different wettability conditions. Various mechanisms responsible for enhancing heavy oil recovery during alkaline flooding are investigated at different wettability conditions. These mechanisms... 

    Dewetting of evaporating thin films over nanometer-scale topographies

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Vol. 90, issue. 1 , July , 2014 ; ISSN: 15393755 Akbarzadeh, A. M ; Moosavi, A ; Moghimi Kheirabadi, A ; Sharif University of Technology
    Abstract
    A lubrication model is used to study dewetting of an evaporating thin film layer over a solid substrate with a nanometer-scale topography. The effects of the geometry of the topography, the contact angle, the film thickness, and the slippage on the dewetting have been studied. Our results reveal that the evaporation enhances the dewetting process and reduces the depinning time over the topography. Also it is shown that the depinning time is inversely proportional to the slippage and increasing the contact angle may considerably reduce the depinning time, while the film thickness increases the depinning time  

    Interaction of 3D dewetting nanodroplets on homogeneous and chemically heterogeneous substrates

    , Article Journal of Physics Condensed Matter ; Vol. 26, Issue. 22 , 2014 ; ISSN: 09538984 Asgari, M ; Moosavi, A ; Sharif University of Technology
    Abstract
    Long-time interaction of dewetting nanodroplets is investigated using a long-wave approximation method. Although three-dimensional (3D) droplets evolution dynamics exhibits qualitative behavior analogous to two-dimensional (2D) dynamics, there is an extensive quantitative difference between them. 3D dynamics is substantially faster than 2D dynamics. This can be related to the larger curvature and, as a consequence, the larger Laplace pressure difference between the droplets in 3D systems. The influence of various chemical heterogeneities on the behavior of droplets has also been studied. In the case of gradient surfaces, it is shown how the gradient direction could change the dynamics. For a... 

    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
    Abstract
    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 physicochemical evaluation of modified HZSM-5 catalyst utilized for production of dimethyl ether from methanol

    , Article Petroleum Science and Technology ; Vol. 32, issue. 8 , Feb , 2014 , pp. 904-911 ; ISSN: 10916466 Pedram, M. Z ; Kazemeini, M ; Fattahi, M ; Amjadian, A ; Sharif University of Technology
    Abstract
    A number of HZSM-5 catalysts modified with 5 wt% Mg, Na, Zr, and Al as well as others modified with 5-60 wt% Zn prepared by wet impregnation. These materials were characterized by the NH3-TPD, XRF, and XRD analyses and tested in a slurry reactor to determine their activities in dehydration of methanol solution in kerosene. Reactions were carried out at 230°C and 19 bar for 4 h of residence time in the reactor. Results showed that in the first series, the catalyst modified with Zr and in the second series, the one modified with 10 wt% Zn led to the highest methanol conversion. It was deduced that elimination of strong acid sites and partial replacement of active cations in the HZSM-5 zeolite... 

    Steganographic schemes with multiple q-ary changes per block of pixels

    , Article Signal Processing ; Vol. 108, issue , 2014 , pp. 206-219 Gholampour, I ; Khosravi, K ; Sharif University of Technology
    Abstract
    A family of matrix embedding steganographic schemes for digital images is investigated. The target schemes are applied to blocks of n pixels in a cover image. In every block, at most m pixels are allowed to change with q-ary steps. We have derived some upper bounds on the embedding efficiency of these schemes for different values on m. It is also shown that these upper bounds approach the general upper bound on the embedding efficiency of q-ary steganography. For the case of q=3, we have shown that there is no feasible optimum member of the family for m=2, although for m=1, a well-known example exists. Instead, for m=2, a new close-to-bound scheme in the family is presented which exploits... 

    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
    Abstract
    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... 

    Low temperature synthesis of carbonate-free barium titanate nanoscale crystals: Toward a generalized strategy of titanate-based perovskite nanocrystals synthesis

    , Article Journal of the American Ceramic Society ; Vol. 97, issue. 7 , 2014 , pp. 2027-2031 Ashiri, R ; Moghtada, A ; Shahrouzianfar, A ; Ajami, R ; Sharif University of Technology
    Abstract
    Synthesis temperature and purity of perovskite materials are key challenges facing the scientific community. This work aims to address these challenges by developing an innovative low temperature synthesis pathway for preparation of carbonate-free perovskite nanocrystals. The method is based on an ultrasound-Assisted wet chemical processing method. Nanocrystals are characterized and observed by X-ray diffraction (XRD), field-emission scanning electron microscopy and high-resolution transmission electron microscopy techniques. XRD studies show that very fine BaTiO3 nanocrystals (<11 nm) free from any by-products such as BaTi2O5 and BaCO3 are synthesized at 50°C. Moreover, the method developed... 

    Characterization of the effect of disturbance on the hydro-mechanical behavior of a highly collapsible loessial soil

    , Article Unsaturated Soils: Research and Applications - Proceedings of the 6th International Conference on Unsaturated Soils, UNSAT 2014 ; Vol. 1, issue , 2014 , p. 261-266 Haeri, S. M ; Khosravi, A ; Ghaizadeh, S ; Garakani, A. A ; Meehan, C. L ; Sharif University of Technology
    Abstract
    Highly collapsible loessial soils are characterized by an open void structure that can experience significant settlement upon loading. In the field, these partially saturated Aeolian deposits are particularly susceptible to wetting-induced collapse. Due to difficulties in preparing undisturbed specimens from highly collapsible soils, previous studies have generally performed laboratory tests on reconstituted specimens with different water contents and densities, and the effect of disturbance on the initial state of the soil was ignored. Disturbance in highly collapsible soil specimens may significantly affect the natural composition of the soil matrix, the non-homogeneous distribution of... 

    A generalized multi-layer information hiding scheme using wet paper coding

    , Article 2014 11th International ISC Conference on Information Security and Cryptology, ISCISC 2014 ; 2014 , p. 210-213 Bidokhti, A ; Ghaemmaghami, S ; Sharif University of Technology
    Abstract
    Multi-layer schemes have been proposed for steganography. Also some authors have combined these methods with the idea of wet paper codes and gained higher embedding efficiency. This paper proposes a generalized multi-layer method for wet paper embedding. First, the cover bits are divided into blocks and, by combining these bits in groups of 3, a pyramid is formed. Next, the secret message is embedded through a layer-by-layer procedure. The proposed method has higher embedding efficiency in some cases and provides more flexibility for choosing the embedding payload, especially in lower payload conditions  

    Investigating the role of ultrasonic wave on two-phase relative permeability in a free gravity drainage process

    , Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 763-771 Keshavarzi, B ; Karimi, R ; Najafi, I ; Ghazanfari, M. H ; Ghotbi, C ; Sharif University of Technology
    Abstract
    In this work, the process of free gravity drainage under the influence of ultrasonic waves was investigated. A glass bead pack porous medium was used to perform free fall gravity drainage experiments. The tests were performed in the presence and absence of ultrasonic waves, and the data of recovery were recorded versus time under both conditions. The wetting phase relative permeability curves were obtained using the data of recovery versus time, based on the Hagoort backward methodology. Subsequently, using the wetting phase relative permeability curve, the relative permeability of non-wetting phases were calculated by performing history matching to the experimental production data. The... 

    Index for characterizing wettability of reservoir rocks based on spontaneous imbibition recovery data

    , Article Energy and Fuels ; Volume 27, Issue 12 , November , 2013 , Pages 7360-7368 ; 08870624 (ISSN) Mirzaei Paiaman, A ; Masihi, M ; Standnes, D. C ; Sharif University of Technology
    2013
    Abstract
    An index for characterizing wettability of reservoir rocks is presented using slope analysis of spontaneous imbibition recovery data. The slope analysis is performed using the known exact analytical solution to infinite acting period of counter-current spontaneous imbibition. The proposed theoretically based wettability index offers some advantages over existing methods: (1) it is a better measure of the spontaneous imbibition potential of rock (because the magnitude is directly proportional to the imbibition rate); (2) there is no need for forced displacement data; (3) there is no need for waiting until the spontaneous imbibition process ceases completely; and (4) the data needed to run the... 

    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
    2013