Search for: calcite
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    Dispersivity, collapsibility and microstructure of a natural dispersive loess from Iran

    , Article 16th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2019, 14 October 2019 through 18 October 2019 ; 2020 Sadeghi, H ; Nasiri, H ; Panahi, P. A ; Sadeghi, M ; Sharif University of Technology
    Asian Regional Conference on Soil Mechanics and Geotechnical Engineering  2020
    A new type of collapsible soil was encountered in Southern Iran and caused some serious technical problems including subsidence, collapse and sinkholes during the construction of Zahedan-Chabahar railway. Field observations indicated that in-situ soil contains excessive amount of salts resulting in dispersive features in response to seepage forces in addition to its collapsibility. Therefore, a systematic research plan including field sampling and laboratory testing was carried out to investigate the observed geotechnical features. Results of physio-chemical tests revealed the dominance of Sodium in excess of 70% relative to total dissolved salts, which results in high dispersive potential.... 

    Polyacids for producing colloidally stable amorphous calcium carbonate clusters in water

    , Article Journal of Applied Polymer Science ; November , 2021 ; 00218995 (ISSN) Jia, X ; Basak Kayitmazer, A ; Ahmad, A ; Ramzan, N ; Li, Y ; Xu, Y ; Sun, S ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    As an important precursor of crystalline phases, amorphous calcium carbonate (ACC), especially ultrasmall ACC clusters, have been attracting great interest in fundamental research, materials chemistry, as well as industrial applications. However, it is still challenging to synthesize stable ACC clusters in water that can be isolated and concentrated without severe aggregation. Herein, we report a facile dialysis method for producing colloidally stable ACC clusters that are well dispersed in water with the protection of specific polycarboxylic acids, which could be also easily deprotected by small-molecule acids like sodium citrate. Inherent proto-calcite short-range order is found to be... 

    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
    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... 

    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
    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... 

    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
    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
    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
    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... 

    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
    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... 

    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
    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... 

    The effect of pH and ionic strength on the transport of alumina nanofluids in water-saturated porous media: Experimental and modeling study

    , Article Journal of Thermal Analysis and Calorimetry ; Volume 137, Issue 4 , 2019 , Pages 1169-1179 ; 13886150 (ISSN) Zareei, M ; Yoozbashizadeh, H ; Madaah Hosseini, H. R ; Sharif University of Technology
    Springer Netherlands  2019
    Alumina nanofluids are one of the most useful nanofluids, especially for increasing the thermal conductivity. Due to importance of porous media in the improvement of heat transfer, this study investigates the transport and retention of gamma alumina/water nanofluid in the water-saturated porous media. For this purpose, alumina nanofluids were introduced to the porous media consisting of water-saturated glass beads possessing various pH values (4, 7 and 10) and different ionic strengths (0.001 M of KCl, CaCl2, AlCl3, K2SO4, CaSO4, Al2(SO4)3, K2CO3 and CaCO3). Then the break through curve of each experiment was drawn and modeled by combining classical filtration theory with... 

    On the size-dependent behavior of drop contact angle in wettability alteration of reservoir rocks to preferentially gas wetting using nanofluid

    , Article Journal of Petroleum Science and Engineering ; Volume 178 , 2019 , Pages 1143-1154 ; 09204105 (ISSN) Azadi Tabar, M ; Ghazanfari, M. H ; Dehghan Monfared, A ; Sharif University of Technology
    Elsevier B.V  2019
    Wettability alteration of rock surfaces toward gas wetting have been recognized as a practical approach for maximizing the production from the gas condensate reservoirs. Most of the reported work in this area applied the so called sessile drop contact angle measurement technique to examine the change in wetting state of a surface. However, the size-dependent wetting behavior of drop which could affect the exact determination of wettability and wettability changes was not well discussed in the previous studies. Therefore, in this work, the size dependency of contact angle for four different liquid-solid-gas systems; i.e., water-calcite-air, water-treated calcite-air (nanofluid treated... 

    Synthesis and polymorph controlling of calcite and aragonite calcium carbonate nanoparticles in a confined impinging-jets reactor

    , Article Chemical Engineering and Processing - Process Intensification ; 2020 Adavi, K ; Molaei Dehkordi, A ; Sharif University of Technology
    Elsevier B.V  2020
    In this article, a confined-impinging-jets reactor (CIJR) was designed and tested successfully for the synthesis of calcium carbonate nanoparticles using the reactive precipitation method. The proposed CIJR comprised of two opposed nozzles placed in a cylindrical chamber. Effects of various operating and design parameters such as supersaturation, feed flow rate, nozzle diameter, reactor diameter, operating temperature, and surface-active agents on the mean particle size, particle size distribution, and the polymorphs of calcium carbonate nanoparticles were investigated carefully. By changing the supersaturation, reactor diameter, jets velocity, operating temperature, and the nozzle diameter,... 

    Stick-slip behavior of sessile drop on the surfaces with irregular roughnesses

    , Article Chemical Engineering Research and Design ; Volume 160 , 2020 , Pages 216-223 Azadi Tabar, M ; Shayesteh, M ; Shafiei, Y ; Ghazanfari, M. H ; Sharif University of Technology
    Institution of Chemical Engineers  2020
    In this work, sessile drop and low-bond axisymmetric drop shape analysis methods were coupled to provide some new aspects on stick-slip behavior as well as stick time of a drop on calcite surfaces. Slightly hydrophobic calcite surfaces typified with three irregular roughnesses were used to create irregular surfaces to mimic defects for the water-calcite-air systems. Polishing papers of 200, 600, and 1200 grit and a polishing machine were used to prepare surfaces. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transform infrared, and atomic force microscopy techniques were employed to evaluate the chemical and physical properties of surfaces. A model was developed to predict... 

    Compare numerical modeling and improved understanding of dynamic sessile drop contact angle analysis in Liquid-Solid-Gas system

    , Article Journal of Petroleum Science and Engineering ; Volume 184 , 2020 Azadi Tabar, M ; Ghazanfari, M. H ; Dehghan Monfared, A ; Sharif University of Technology
    Elsevier B.V  2020
    Dynamic contact angle measurement; as a standard method for surface wettability analysis, is usually conducted through the analysis of sessile drops formed following the low rate injection of fluid from beneath through a drilled hole via an injection needle. However, understanding/characterizing the changes of drop contact angle from the point where the flat solid surface begins is not well discussed yet. Moreover, during the evaluation of size-dependent behavior of contact angle of millimeter-scale drops, the effect of the drilled hole is ignored. In this regard, in the current study, the experimental and thermodynamic characterizations of the sessile drop advancing contact angle... 

    Characterization and calcination behavior of a low-grade manganese ore

    , Article Materials Today Communications ; Volume 25 , 2020 Cheraghi, A ; Becker, H ; Eftekhari, H ; Yoozbashizadeh, H ; Safarian, J ; Sharif University of Technology
    Elsevier Ltd  2020
    Characterization and calcination behavior of a low-grade manganese ore, as a part of Mn ferroalloys production, was studied by XRF, ex-situ XRD, in-situ XRD, and SEM-EDS techniques. Calcination experiments were carried out at and up to 900 °C (1173 K) in air and argon atmospheres. The samples were in particles and powder forms. The results indicated that both quartz and calcite phases in the ore exhibit a bimodal spatial distribution; as relatively large regions and finely distributed in the Mn- and Fe-containing phases. By Rietveld analysis of the in-situ XRD data, the reactions occurring upon heating during the calcination process were deduced. Thermal decomposition and reactive diffusion... 

    Microorganisms’ effect on the wettability of carbonate oil-wet surfaces: implications for MEOR, smart water injection and reservoir souring mitigation strategies

    , Article Journal of Petroleum Exploration and Production Technology ; Volume 10, Issue 4 , 2020 , Pages 1539-1550 Jahanbani Veshareh, M ; Ayatollahi, S ; Sharif University of Technology
    Springer  2020
    In upstream oil industry, microorganisms arise some opportunities and challenges. They can increase oil recovery through microbial enhanced oil recovery (MEOR) mechanisms, or they can increase production costs and risks through reservoir souring process due to H2S gas production. MEOR is mostly known by bioproducts such as biosurfactant or processes such as bioclogging or biodegradation. On the other hand, when it comes to treatment of reservoir souring, the only objective is to inhibit reservoir souring. These perceptions are mainly because decision makers are not aware of the effect microorganisms’ cell can individually have on the wettability. In this work, we study the individual effect... 

    Impact of rock mineralogy on reservoir souring: A geochemical modeling study

    , Article Chemical Geology ; Volume 555 , November , 2020 Li, H ; Zhang, L ; Liu, L ; Shabani, A ; Sharif University of Technology
    Elsevier B. V  2020
    The petroleum industry suffers from reservoir souring phenomena, which has negative impacts on production facilities, health, and environment. Injection of incompatible water into the reservoir (waterflooding), which is considered as an enhanced oil recovery (EOR) method, is one of the most common causes of reservoir souring. In general, injected brine, especially seawater, contains high amounts of sulfate ion (SO42−). A high concentration of sulfate in the presence of sulfate-reducing bacteria (SRB) leads to the microbial reservoir souring. During this phenomenon, sulfide, specifically hydrogen sulfide gas (H2S) appears in the producing fluid of the reservoir. In this paper, a coupled... 

    Static and dynamic behavior of foam stabilized by modified nanoparticles: Theoretical and experimental aspects

    , Article Chemical Engineering Research and Design ; Volume 158 , 2020 , Pages 114-128 Suleymani, M ; Ashoori, S ; Ghotbi, C ; Moghadasi, J ; Kharrat, R ; Sharif University of Technology
    Institution of Chemical Engineers  2020
    Gas flooding is a practical secondary scenario for enhanced oil recovery. Channeling and fingering of the injected gas are the major problems facing this technique. These challenges can be mitigated by the injection of gas as foam. However, foam stability influences the overall efficiency of the process, which could be improved by nanoparticles (NPs). This work provides a theoretical and experimental analysis of the NPs wettability effects on foam behavior, in both static and dynamic states. The treated calcite (CaCO3) NPs along with a cationic surfactant (HTAB) were used for this purpose. By comparison of theoretical and experimental data, it was shown that the foam stability in the... 

    Using molecular dynamic simulation data of calcite in a wide pressure range to calculate some of its thermodynamic properties via some universal equations of state

    , Article Molecular Physics ; Volume 106, Issue 21-23 , 2008 , Pages 2545-2556 ; 00268976 (ISSN) Akbarzadeh, H ; Shokouhi, M ; Parsafar, G. A ; Sharif University of Technology
    Molecular dynamics, MD, simulation of calcite (CaCO3) is selected to compare the p-v-T behaviour of some universal equations of state, UEOS, for the temperature range 100 K ≤ T 800 ≤ K, and pressures up to 3000 kbar. The isothermal sets of p-v-T data generated by simulation were each fitted onto some three- and two-parameter EOSs including Parsafar and Mason (PM), Linear Isotherm Regularity (LIR), Birch-Murnaghan (BM), Shanker, Vinet, Baonza and Modified generalized Lennard-Jones (MGLJ) EOSs. It is found that the MD data satisfactorily fit these UEOS with reasonable precision. Some features for a good UEOS criteria such as temperature dependencies of coefficients, pressure deviation,... 

    Atomistic insight into the behavior of ions at an oil-bearing hydrated calcite surface: implication to ion-engineered waterflooding

    , Article Energy and Fuels ; Volume 35, Issue 16 , 2021 , Pages 13039-13054 ; 08870624 (ISSN) Badizad, M. H ; Koleini, M. M ; Greenwell, H. C ; Ayatollahi, S ; Ghazanfari, M. H ; Sharif University of Technology
    American Chemical Society  2021
    This research provides an atomistic picture of the role of ions in modulating the microstructural features of an oil-contaminated calcite surface. This is of crucial importance for the rational design of ion-engineered waterflooding, a promising technique for enhancing oil recovery from carbonate reservoirs. Inspired by a conventional lab-scale procedure, an integrated series of molecular dynamics (MD) simulations were carried out to resolve the relative contribution of the major ionic constituent of natural brines (i.e., Na+, Cl-, Mg2+, Ca2+, and SO42-) when soaking an oil-bearing calcite surface in different electrolyte solutions of same salinity, namely, CaCl2, MgCl2, Na2SO4, MgSO4, and...