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    Improvement of Collapsible Soils Using Biocementation Method (Case Study of Gorgan Loess)

    , M.Sc. Thesis Sharif University of Technology Aghaie Lahroodi, Mehrdad (Author) ; Haeri, Mohsen (Supervisor)
    Abstract
    Collapsible soils have been encountered in many parts of the world such as Gorgan (a city in North of Iran). In these soils, sudden and large volume changes occur while the water content, loading pressure or both, are passed a threshold limit. One of the serious problems that may occur in the structures constructed on collapsible soils is the catastrophic settlements resulting from increase of water content in the soils. In this research, improvement of mechanical properties of loessial collapsible soil taken from Gorgan has been investigated using biocementation method. There are some microbial processes that can lead to biocementation, which one of them is microbially induced calcite... 

    The Dynamic Behavior of Calcite Cemented Gravelly Sand – A Case Study of Tehran Soil

    , Ph.D. Dissertation Sharif University of Technology Shakeri, Mohammad Reza (Author) ; Haeri, Mohsen (Supervisor) ; Sajjadi, Ali Akbar (Supervisor)
    Abstract
    An understanding of the effect of degree of cementation on static and dynamic behaviour of cemented soils is becoming increasingly important in design and analysis of geotechnical engineering problems. Naturally cemented coarse-grained soils are widely present in many parts of the world. Misunderstanding of the behaviour of such soils could lead to underestimate or overestimate of the soil parameters. Previous studies conducted by Haeri and his co-workers show that most of the alluvial deposit of Tehran, the capital city of Iran, has a soil with cemented nature. The amount and characteristics of the cementation of the deposit varies in different parts from highly cemented in the north to... 

    The Static Behavior of Calcite Cemented Gravely Sand – Tehran Alluvium Case Study

    , M.Sc. Thesis Sharif University of Technology Adl, Mahmoud Reza (Author) ; Haeri, Mohsen (Supervisor)
    Abstract
    An understanding of the effect of degree of cementation on static behavior of cemented soils in becoming increasingly important in design and analysis of geotechnical engineering problems. Naturally cemented coarse-grained soils are widely present in many parts of the world. Misunderstanding of the behavior of such soils could lead to under or overestimate of the soil parameters. Previous studies conducted by Prof. Haeri and his co-workers show that most of the alluvial deposit of Tehran, the capital city of Iran. The amount and characteristics of the cementation of the deposit varies in different parts from highly cemented in the north to non-cemented in the south. This deposit consists of... 

    Constructing Calcite Core by Microbially Induced Calcite Precipitation (MICP) Usable in Oil and Gas Tests

    , M.Sc. Thesis Sharif University of Technology Ali Doust Salimi, Nazanin (Author) ; Yaghmaei, Soheila (Supervisor) ; Bazargan, Mohammad (Supervisor) ; Ghobadi Nejad, Zahra (Co-Supervisor)
    Abstract
    Acidizing is the most widely performed job to remove the formation damage, and enhance the oil recovery. Different models have been introduced to design the optimized condition for acidizing. However, none of them are able to predict the optimum injection flow rate in the actual application. As a result, Calcite cores are extracted from reservoirs for conducting experiments and modifying the present models. Nevertheless, acidizing is an intrusive technique destroying the costly extracted cores. Thus, there is a need to construct calcite cores of various porosities and permeabilities to take advantage of them in acidizing modelling.Microbially induced calcite precipitation is a well-known... 

    Investigation of Interface Phenomena in Low Salinity/Smart Waterflooding by Applying Molecular Dynamics Simulation

    , Ph.D. Dissertation Sharif University of Technology Badizad, Mohammad Hassan (Author) ; Ayatollahi, Shahab (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor) ; Koleini, Mhammad Mehdi (Co-Supervisor)
    Abstract
    Low salinity/smart waterflooding is simple to apply and a promising enhanced oil recovery method in which ion-tuned saltwater is injected into subsurface oil reservoirs. Many aspects of this operation, in particular those pertaining to nano-scale, are not yet fully understood. The present dissertation is an attempt to shed light on the microscopic properties and behavior of rock/brine/oil interfaces throughout low salinity/smart waterflooding. Several simulations were carried out for oil/brine and calcite/brine categories each containing various ions and hydrocarbons compounds. The surface contribution of non-functional oil compounds (aromatics and aliphatics) near brine medium was... 

    Production of Biodiesel Using Calcite Stone as Support Catalyst

    , M.Sc. Thesis Sharif University of Technology Talebi, Morteza (Author) ; Khorasheh, Farhad (Supervisor) ; Larimi, Afsanehsadat (Supervisor)
    Abstract
    The aim of this study is developing and investigating heterogeneous catalysts based on natural calcite for the transesterification of canola oil and methanol in order to produce biodiesel as a renewable and alternative fuel for fossil fuels. At first calcite was calcined at high temperature to decompose calcium carbonate to calcium oxide. Afterward, Mg-Zr/CaO catalysts were prepared with mass ratio of 2:1 Mg:Zr and different weight percent(2.5, 5,7.5 and 10 wt%) on calcite supported by impregnation method. In order to characterized synthesized catalysts used different analysis such as energy dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy... 

    The effect of calcite cementation on the mechanical behavior of gravely sands

    , Article 14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, 23 May 2011 through 27 May 2011, Hong Kong ; 2011 Adl, M. R ; Sharif University of Technology
    Abstract
    The behavior of a cemented gravely sand is studied using triaxial tests. Undrained tests were performed on saturated specimens, and stress-strain characteristics of the soil, along with volumetric and pore pressure changes, were recognized. Artificially cemented samples are prepared using calcite crystallization as the cementing agent in different percentages. The tests were done in usual range of confining pressures, from 50 to 1200 kPa. The results shows that dilation occurs even at highest confining pressure and least cement content. Also the friction angle of soils increases slightly with cement content, but cohesion intercept increasing is more noticeable  

    Adsorption of silica nanoparticles onto calcite: Equilibrium, kinetic, thermodynamic and DLVO analysis

    , Article Chemical Engineering Journal ; Volume 281 , December , 2015 , Pages 334-344 ; 13858947 (ISSN) Dehghan Monfared, A ; Ghazanfari, M. H ; Jamialahmadi, M ; Helalizadeh, A ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Recently, application of silica nanoparticles (SNP) for enhancing oil recovery during water flooding has been much attended. However, understanding how rock and nanoparticles (NP) interacts through adsorption onto the carbonate reservoir rocks is not well discussed. In this work, adsorption behavior of SNP onto the calcite had been characterized, through kinetic, equilibrium, thermodynamics and electrokinetic studies as well as interaction energy analysis by DLVO theory. Also, field emission scanning electron microscopy (FESEM) was utilized to visualize the adsorption process. It had been found that kinetic behavior of SNP-calcite system followed the pseudo-second order model. Equilibrium... 

    Mechanistic study of wettability alteration of oil-wet calcite: The effect of magnesium ions in the presence and absence of cationic surfactant

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 482 , October , 2015 , Pages 403-415 ; 09277757 (ISSN) Karimi, M ; Al Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Over 60% of the world's discovered oil reserves are held in carbonate reservoirs, which are mostly naturally fractured. Conventional water flooding results in low oil recovery efficiency in these reservoirs as most of them are oil-wet. On account of negative capillary forces, injected brine cannot penetrate simply into an oil-wet matrix of fractured formations to force the oil out. Wettability alteration of the rock surface to preferentially more water-wet state has been extensively studied using both smart water and surfactants separately. This study aims to study the effects of Mg2+ as one of the most important wettability influencing ions on the wetting properties of oil-wet carbonate... 

    Molecular dynamics simulation investigation of hexanoic acid adsorption onto calcite (1014)surface

    , Article Fluid Phase Equilibria ; Volume 387 , 2015 , Pages 24-31 ; 03783812 (ISSN) Ghatee, M. H ; Koleini, M. M ; Ayatollahi, S ; Sharif University of Technology
    Abstract
    In this paper we report the results of classical molecular dynamics (MD) simulation of hexanoic acid adsorption on calcite (101-4) surface plane using Pavese and AMBER force fields for calcite and hexanoic acid, respectively. Pair correlation function, strictly suggests a well-structured adsorption. Density profile indicates the adsorption occurs through double-bonded O atom of the acid head group by direct interaction with Ca atom at calcite surface. Adsorption orientation of H and double-bonded O atoms was found to be as lock and key with respect to calcite surface Ca and O atoms, facilitating an effective adsorption. Adsorption time evolution indicates that O atom adsorption is... 

    Impact of sulfate ions on wettability alteration of oil-wet calcite in the absence and presence of cationic surfactant

    , Article Energy and Fuels ; Volume 30, Issue 2 , 2016 , Pages 819-829 ; 08870624 (ISSN) Karimi, M ; Al-Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    The modification of the surface wetting characteristics in fractured oil-wet carbonate reservoirs, by reversing wettability from oil-wet to water-wet, leads to improved oil recovery. However, in order to obtain a successful oil recovery process, it is crucial to understand the active mechanisms of wettability alteration. This study looks at the effect of sulfate ions as one of the most promising wettability influencing ions on the wetting properties of oil-wet calcite; the effect is studied both with and without the presence of cationic surfactant and possible mechanisms of wettability alteration are explored. A number of analytical techniques were utilized to analyze the mineral surface... 

    Potential application of silica nanoparticles for wettability alteration of oil-wet calcite: A mechanistic study

    , Article Energy and Fuels ; Volume 30, Issue 5 , 2016 , Pages 3947-3961 ; 08870624 (ISSN) Dehghan Monfared, A ; Ghazanfari, M. H ; Jamialahmadi, M ; Helalizadeh, A ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    Oil recovery from carbonate reservoirs can be enhanced by altering the wettability from oil-wet toward water-wet state. Recently, silica nanoparticle (SNP) suspensions are considered as an attractive wettability alteration agent in enhanced oil recovery applications. However, their performance along with the underlying mechanism for wettability alteration in carbonate rocks is not well discussed. In this work, the ability of SNP suspensions, in the presence/absence of salt, to alter the wettability of oil-wet calcite substrates to a water-wet condition was investigated. In the first step, to ensure that the properties of nanofluids have not been changed during the tests, stability analysis... 

    Bonding, structural and thermodynamic analysis of dissociative adsorption of H3O+ ion onto calcite (10 1 ¯ 4) surface: CPMD and DFT calculations

    , Article Journal of Molecular Modeling ; Volume 23, Issue 12 , 2017 ; 16102940 (ISSN) Ghatee, M. H ; Koleini, M. M ; Sharif University of Technology
    Abstract
    We used density functional theory (DFT) and Car-Parrinello molecular dynamics (CPMD) simulation to investigate the adsorption and bond formation of hydronium ion (H3O+) onto a (10 1 ¯ 4) calcite surface. For surface coverage of 25% to 100%, the nature of H3O+ interaction was explored through electron density and energetics in the context of bond critical points. The adsorbate–adsorbent structure was studied by simulation of pair correlation function. The results revealed that dissociation into water molecule(s) and proton(s) complements H3O+ ion(s) adsorbtion. The H2O molecule adsorbs onto the surface via its O atom, and interacts with surface calcium in a closed-shell mode; the H+ ion makes... 

    Wettability alteration modeling for oil-wet calcite/silica nanoparticle system using surface forces analysis: contribution of DLVO versus non-DLVO interactions

    , Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 43 , 2018 , Pages 14482-14492 ; 08885885 (ISSN) Dehghan Monfared, A ; Ghazanfari, M. H ; Kazemeini, M ; Jamialahmadi, M ; Helalizadeh, A ; Sharif University of Technology
    American Chemical Society  2018
    Abstract
    In this work, application of silica nanoparticles for wettability alteration of initially oil-wet calcite was investigated through analysis of surface forces and DLVO theory. Doing so, the wettability and zeta potential of calcite surfaces were measured through the sessile drop method and an in-house experimental setup, respectively. Primary evaluation indicated that incorporating DLVO terms in the Frumkin-Derjaguin model was not sufficient to describe the wettability in an oil-wet calcite/nanofluid system. Sensitivity analysis showed that calculating the double-layer interaction using constant potential-constant potential boundaries along with structural hydrophobic forces (non-DLVO... 

    Predicting the rock wettability changes using solutions with different pH, through streaming potential measurement

    , Article Journal of Petroleum Science and Engineering ; Volume 167 , 2018 , Pages 20-27 ; 09204105 (ISSN) Rahbar, M ; Pahlavanzadeh, H ; Ayatollahi, S ; Manteghian, M ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    The high reactivity of the carbonate rocks at various pH makes it difficult to evaluate the wettability, hence to find the recovery mechanisms behind modified waterflood in carbonate reservoirs. More recently, the streaming potential measurement is introduced as a method of electrokinetic phenomena more relevant to the subsurface systems. Regarding few experimental studies and in order to improve our understanding on streaming potential measurement, the electrokinetic studies on quartz and calcite surface were conducted as a function of pH in the range of 1.5–11.5 using an in-house novel setup of streaming potential measurement. High sensitivity of streaming potential coupling coefficient to... 

    An experimental study on mechanical behavior of a calcite cemented gravelly sand

    , Article Geotechnical Testing Journal ; Volume 41, Issue 3 , May , 2018 , Pages 494-507 ; 01496115 (ISSN) Shakeri, M. R ; Haeri, S. M ; Shahrabi, M. M ; Khosravi, A ; Sajadi, A. A ; Sharif University of Technology
    ASTM International  2018
    Abstract
    In the study presented herein, a simple method for laboratory calcite cementation of a reconstituted gravelly sand was presented. This method was used to prepare cemented gravelly sand specimens, which have similar natural characteristics to alluvial deposit of the city of Tehran. The formation and distribution of calcite bonds, as well as the effectiveness of the presented calcite cementation method in increasing interparticle cohesion, as observed in weakly to moderately cemented soil in Tehran, were evaluated by means of chemical analysis, X-ray diffraction technique, and unconfined compressive strength tests. The cementation technique was used to prepare triaxial specimens with calcite... 

    Effects of low salinity water on calcite/brine interface: a molecular dynamics simulation study

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 537 , January , 2018 , Pages 61-68 ; 09277757 (ISSN) Koleini, M. M ; Fattahi Mehraban, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    Calcite is among the most abundant minerals organizing the oil reservoir formation and therefore its surface properties play a central role in the increase of the oil recovery efficiency. The effect of low-salinity water in carbonate rocks reveals that brine composition and salinity can improve the oil recovery in carbonates through wettability alteration. However, the specific mechanism for wettability changes that leads to improved oil recovery in calcite is not well understood. To obtain deeper insights at atomic level into the understanding the characteristics of the calcite-water interface, we performed classical molecular dynamics simulations in the presence of different ions in brine... 

    Mechanism of nanostructured fluorapatite formation from CaO, CaF2 and P2O5 precursors by mechanochemical synthesis

    , Article Progress in Reaction Kinetics and Mechanism ; Volume 43, Issue 3-4 , 2018 , Pages 201-210 ; 14686783 (ISSN) Nikonam Mofrad,, R ; Sadrnezhaad, S. K ; Vahdati Khaki, J ; Sharif University of Technology
    Science Reviews 2000 Ltd  2018
    Abstract
    We determined the mechanism of mechanochemical synthesis of fluorapatite from CaO, CaF2 and P2O5 by characterisation of the intermediate compounds. We used atomic absorption spectroscopy, X-ray diffraction, field emission scanning electron microscopy, FTIR spectroscopy and transmission electron microscopy to find the transitional compounds. Investigation of the binary and ternary powder mixtures revealed the appearance of H3PO4, Ca(OH)2, Ca2P2O7 and CaCO3 as the intermediate compounds. At early stages of the milling, conversions of P2O5 to H3PO4 and CaO to Ca(OH)2 occurred in the wet atmosphere. Later, a combination of Ca(OH)2 and H3PO4 formed Ca2P2O7 while the unreacted CaO was converted to... 

    An atomistic insight into the implications of ion-tuned water injection in wetting preferences of carbonate reservoirs

    , Article Journal of Molecular Liquids ; Volume 293 , 2019 ; 01677322 (ISSN) Koleini, M.M ; Badizad, M. H ; Ghatee, M. H ; Ayatollahi, S ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    The efficiency of water flooding methods is known to improve by applying ion-tuned water injection. Although there is a consensus that such improvement happens through reversing reservoir wettability characteristics to more water-wet state, the true impact of ions is still ambiguous among contradictory debates. The well-known molecular dynamics (MD) simulation techniques would shed light on such ambiguities to gain deep atomic-scale understanding of the process. Results from MD simulations show that the presence of Na+ and Cl¯ ions leads to the formation of an electrical double layer in adjacency of calcite surface while Mg2+ ions dominantly make complexes with hydrocarbons throughout the... 

    Wettability alteration of oil-wet carbonate porous media using silica nanoparticles: Electrokinetic characterization

    , Article Industrial and Engineering Chemistry Research ; Volume 58, Issue 40 , 2019 , Pages 18601-18612 ; 08885885 (ISSN) Dehghan Monfared, A ; Ghazanfari, M. H ; Sharif University of Technology
    American Chemical Society  2019
    Abstract
    Application of nanoparticles for wettability alteration offers a practical approach to resolve some surface-related problems encountered in the nowadays technological process. Examples are underground/subsurface engineering implications, including the enhanced oil recovery from the oil-wet carbonate reservoirs. However, the common wettability evaluating techniques such as contact angle and flotation cannot be representative of the dynamic phenomena occurring at the pore scale and hence are unable to give accurate information about the process. Therefore, in the present work, the electrokinetic evaluations are utilized to explore the wettability alteration of initially oil-wet carbonate rock...