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Tehrān, Iran

Esmaeilzadeh P.,University of Tehran | Hosseinpour N.,University of Tehran | Bahramian A.,University of Tehran | Fakhroueian Z.,University of Tehran | Arya S.,NIOC RandD
Fluid Phase Equilibria | Year: 2014

We have studied air-water and oil-water interfacial tensions of systems containing both surfactants and ZrO2 nanoparticles. Anionic surfactant (sodium dodecyl sulfate, SDS), Cationic surfactant (Dodecyl trimethyl ammonium bromide, C12TAB), and nonionic surfactant (Lauryl alcohol 7 mole ethoxylate, LA7) effectively decrease n-heptane-water interfacial tension and air-water surface tension. At water-air interface, inclusion of negatively charged ZrO2 nanoparticles considerably alters the surface activity of SDS molecules and has negligible impact on the surface tension of CTAB and LA7 solutions. At n-heptane-water interface and below the critical micelle concentration (cmc) of the selected surfactants, addition of nanoparticles increases the surface activity of all selected surfactants and reduces the interfacial tension. At and above cmc, nanoparticles have no impact on the interfacial tension. The calculated adsorption energies show that nanoparticles are surface active at oil-water interface with negligible tendency toward adsorption at air-water interface. Inclusion of nanoparticles showed strongest impact on the interfacial behavior of LA7 solutions, resulting in almost constant interfacial tension value in all ranges of surfactant concentration. Dynamic light scattering technique, zeta potential measurement, and centrifugation of the nanofluids are performed to explain the interfacial behavior of nanoparticle-surfactant systems. © 2013 Elsevier B.V. Source

Esmaeilzadeh P.,Iran University of Science and Technology | Fakhroueian Z.,University of Tehran | Bahramian A.,University of Tehran | Arya S.,NIOC RandD
Journal of Nano Research | Year: 2013

This work investigates the effects of nanometric (5-8 nm) ZrO2 nanoparticles on adsorption of two surfactants, SDS (sodium dodecyl sulfate) and C12TAB (dodecyl trimethyl ammonium bromide) into oil/water, air/water and solid/water interfaces. Increasing the concentration of nanoparticles reduces the interfacial tension and surface tension of SDS at low surfactant concentration (< cmc) but it has a minor effect on interfacial and surface tension of C12TAB. Repulsive columbic interactions between SDS molecules and nanoparticles can cause the higher adsorption of surfactant at the oil/water interface. Adsorption of both surfactants on carbonate rock increases by adding nanoparticles to the system. This possibly happened because of the formation of surfactant-nanoparticle negatively charged aggregates that tend to adsorb on positively charged surface layer of carbonate rock. ZrO 2 nanoparticles are surface active at the oil/water interface too, as the results of interfacial tension indicate they can decrease the nheptane/water IFT about 14 units. © (2013) Trans Tech Publications, Switzerland. Source

Mohammadi M.,University of Tehran | Akbari M.,University of Tehran | Fakhroueian Z.,University of Tehran | Bahramian A.,University of Tehran | And 2 more authors.
Energy and Fuels | Year: 2011

Asphaltene precipitation causes several problems during crude oil production, transportation, and refinery processes. Therefore, finding an inhibitor to prevent or delay asphaltene precipitation is of paramount importance. In this work, effects of TiO2, ZrO2, and SiO2 fine nanoparticles in organic-based nanofluids have been investigated to study their potential for stabilizing asphaltene particles in oil. To this end, polarized light microscopy has been applied to determine the onset of asphaltene precipitation by titration of dead oil samples from Iranian crude oil reservoirs with n-heptane in the presence of nanofluids. Results show that rutile (TiO2) fine nanoparticles can effectively enhance the asphaltene stability in acidic conditions and act inversely in basic conditions. It was found that the required amount of n-heptane for destabilizing the colloidal asphaltene is considerably higher in presence of TiO2 nanofluids at pH below 4. The FTIR spectroscopy indicates changes in n-heptane insoluble asphaltene when acidic TiO2 nanofluid is used as inhibitor. According to the results obtained by FTIR spectroscopy, TiO2 nanoparticles can enhance the stability of asphaltene nanoaggregates through formation of hydrogen bond at acidic conditions. This is while other materials used in this experiment, as well as the TiO2 nanoparticles in basic conditions, are unable to form any hydrogen bond - hence their incapability to prevent asphaltene precipitation. Dynamic light scattering (DLS) measurements also have been performed to explain the mechanism of asphaltene precipitation in the presence of nanoparticles. © 2011 American Chemical Society. Source

van Buchem F.S.P.,French Institute of Petroleum | van Buchem F.S.P.,Maersk Oil | Allan T.L.,CSIRO | Laursen G.V.,Statoil | And 9 more authors.
Geological Society Special Publication | Year: 2010

A regional sequence stratigraphic model is proposed for the Oligo-Miocene Asmari and Pabdeh Formations in the Dezful Embayment of SW Iran. The model is based on both new detailed sedimentological observations in outcrops, core and well logs, and an improved high-resolution chronostratigraphic framework constrained by Sr isotope stratigraphy and biostratigraphy. A better understanding of the stratigraphic architecture distinguishes four, geographically separated types of Asmari reservoirs. Three Oligocene sequences (of Rupelian, early Chattian and late Chattian age) and three Miocene sequences (of early Aquitanian, late Aquitanian and early Burdigalian age) have been distinguished, representing a period of 15.4 Ma. The stratigraphic architecture of these sequences is primarily controlled by glacio-eustatic sea-level fluctuations, which determined the distribution of carbonates, sandstones and anhydrites in this sedimentary system. Tectonic control became important in the Burdigalian with a regional tilt down towards the NE. The lithological heterogeneity, the complex geometries, and both early and late diagenetic alterations are the basis for a classification of four main stratigraphic reference types for the Asmari Reservoirs: Type 1, sandstone dominated; Type 2, mixed carbonate-siliciclastic; Type 3, mixed carbonate-anhydrite; and Type 4, carbonate dominated. The sequence stratigraphic model predicts how and when these types change laterally from one to another. © The Geological Society of London 2010. Source

Nazari Moghaddam R.,University of Tehran | Nazari Moghaddam R.,Heriot - Watt University | Bahramian A.,University of Tehran | Fakhroueian Z.,University of Tehran | And 2 more authors.
Energy and Fuels | Year: 2015

Nanofluids have been recently proposed as new chemical agents for enhanced oil recovery from oil reservoirs. Various nanofluids have been studied in that regard and reported in the literature, verifying the capability of nanostructured materials in enhancing the oil recovery through alteration of rock wettability. In this study, the impacts of different nanofluids of zirconium dioxide (ZrO2), calcium carbonate (CaCO3), titanium dioxide (TiO2), silicon dioxide (SiO2), magnesium oxide (MgO), aluminum oxide (Al2O3), cerium oxide (CeO2), and carbon nanotube (CNT) on the wettability of carbonate rocks were investigated. A series of preliminary contact angle evaluations were performed to screen the nanoparticles. The performances of the selected nanofluids were evaluated by spontaneous imbibition and core flooding experiments. Results of spontaneous imbibition tests and coreflooding experiments confirm the active roles of CaCO3 and SiO2 nanoparticles for enhancing oil recovery. In addition, the effect of nanofluid injection on rock surface wettability was examined by drainage capillary pressure measurement. It is shown that the irreducible water saturation and the entry capillary pressure were both increased after treatment by CaCO3 nanaofluid. Moreover, the structural disjoining pressure gradient is proposed to be the responsible mechanism for changing wettability. Both experiments and theoretical calculations prove that disjoining pressure of the nanoparticles layer near the contact point can be high enough to remove oil from the surface. © 2015 American Chemical Society. Source

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