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disjoining-pressure
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Morphology of nanodroplets on structured surfaces
, Article Journal of Physics D: Applied Physics ; Volume 46, Issue 21 , May , 2013 ; 00223727 (ISSN) ; Moosavi, A ; Sharif University of Technology
2013
Abstract
We report different morphologies of nanodroplets over various topographical features of the supporting substrates. The effects of different parameters such as the profile of the disjoining pressure, droplet size and the geometrical parameters are studied and discussed. Also, the effects of a coating layer on the surface of the substrate are determined. It is demonstrated that the nanodroplets at some positions are not stable and gradually move to more stable positions so that the system has less energy. For grooves this results in a series of morphology diagrams of the nanodroplets over the grooves as a function of the grooves' width and the liquid volume
Investigation of rock and fluid interactions during engineered water flooding in dolomite reservoir rocks
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; 2020 ; Masihi, M ; Safekordi, A. A ; Ayatollahi, S ; Sadeghnejad, S ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
Engineered water (EW) flooding is one of the enhanced oil recovery (EOR) techniques in carbonate reservoirs. In this method, the wettability of reservoir rock is altered by controlling the amount of various ions in the injected brine. The thermodynamics of wettability is related to the surface interactions and stability of water film on a rock surface. It can be identified by calculating disjoining pressure isotherms. In this study, core flooding tests, contact angle and zeta potential measurements along with the disjoining pressure isotherm calculation by the DLVO theory were used to investigate the wettability alteration of dolomite rock. Four brines include reservoir formation water...
Dynamics of electrostatic interaction and electrodiffusion in a charged thin film with nanoscale physicochemical heterogeneity: Implications for low-salinity waterflooding
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 650 , 2022 ; 09277757 (ISSN) ; Mahani, H ; Niasar, V ; Sharif University of Technology
Elsevier B.V
2022
Abstract
The slow kinetics of wettability alteration toward a more water-wetting state by low-salinity waterflooding (LSWF) in oil-brine-rock (OBR) systems is conjectured to be pertinent to the electrokinetic phenomena in the thin brine film. We hypothesize that the nanoscale physicochemical heterogeneities such as surface roughness and surface charge heterogeneity at the rock/brine interface control further the dynamics of electrodiffusion and electrostatic disjoining pressure (Πel), thus the time-scale and the magnitude of the low salinity effect (LSE). In this regard, film-scale computational fluid dynamics (CFD) simulations were performed. The coupled Poisson-Nernst-Planck (PNP) equations were...
Three Dimensional Simulation of Morphology of Nanodroplets Near and on Structured Substrates
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Mesoscopic hydrodynamic equations are solved employing a VOF based method to investigate the equilibrium shape of nanodroplets positioned over various topographic geometries of the supporting substrate for three-dimensional systems. By taking into account liquid-liquid and liquid-solid interactions a complex distribution for inter-molecular forces over the substrates (the disjoining pressure) is observed. In this research we show that motion of nanodroplets not only caused by contact angle difference in drplets two sides, but also depend on disjoining pressure parameters.Geometries with increasing complexities, from wedges to three dimensional edges and wedges, were explored with the main...
Coarsening dynamics of dewetting nanodroplets on chemically patterned substrates
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 86, Issue 1 , July , 2012 ; 15393755 (ISSN) ; Sharif University of Technology
2012
Abstract
Mesoscopic hydrodynamic equations are solved to investigate coarsening dynamics of two interacting nanodroplets on chemically patterned substrates. The effects of different parameters such as the surface chemical pattern, the slip length, the profile of the disjoining pressure, the size of the droplets, and the contact angles on the coarsening are studied. Our results reveal that the presence of a chemical heterogeneity can enhance or weaken the coarsening dynamics depending on the pattern type and positions of the droplets on the substrate. Also increasing the contact angles to values larger than a critical value may qualitatively change the coarsening process, and the profile of the...
Dynamic Simulation of Wettability Alteration Induced by Low-Salinity-Effect: Study of Phenomena within Thin Water Film
, M.Sc. Thesis Sharif University of Technology ; Mahani, Hassan (Supervisor) ; Joekar Niasar, Vahid (Co-Supervisor)
Abstract
Recent experimental studies have demonstrated that the lowering of brine could alter the wettability of the oil-brine-rock systems from an oil-wetting state toward a more water-wetting state. This so-called “Low-salinity effect” (LSE) is one of the main effects of the enhanced oil recovery technology based on low-salinity waterflooding. “Double layer expansion” (DLE) in the thin brine film is proposed as the principal mechanism of this phenomenon. Nonetheless, the role of the electrical behavior of the oil/brine and rock/brine interfaces on the kinetics and dynamics of this process is not well understood. Moreover, since most of the previous works have either dealt with a thin film at...
Coarsening dynamics of nanodroplets on topographically structured substrates
, Article Journal of Physics Condensed Matter ; Volume 25, Issue 4 , 2013 ; 09538984 (ISSN) ; Moosavi, A ; Sharif University of Technology
2013
Abstract
Employing a biharmonic boundary integral method with linear elements, coarsening dynamics of nanodroplets on topographical step heterogeneity is investigated. It is shown that the step height and droplet configuration have an influential effect on the dynamics. Increasing the step height slows down the process while locating the droplets close to the step boosts the coarsening rate. Considering a slip boundary condition enhances the dynamics and reveals a transition in the droplet migration direction. Our results reveal that increasing the surface wettability weakens the dynamics. Various types of the disjoining pressure over the step are also considered and their effects on the coarsening...
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 ; Ashoori, S ; Ghotbi, C ; Moghadasi, J ; Kharrat, R ; Sharif University of Technology
Institution of Chemical Engineers
2020
Abstract
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...
The impact of the electrical behavior of oil-brine-rock interfaces on the ionic transport rate in a thin film, hydrodynamic pressure, and low salinity waterflooding effect
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 620 , 2021 ; 09277757 (ISSN) ; Mahani, H ; Niasar, V ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Wettability alteration is the principal low-salinity-effect (LSE) in many oil-brine-rock (OBR) systems. Our recent experimental results have demonstrated that wettability alteration by low salinity is slow. It is expected that the electrical behavior of oil/brine and rock/brine interfaces and the water film geometry control both the transient hydrodynamic pressure, and the time-scale of ionic transport in the film, thus the kinetics and degree of wettability alteration. In this paper, the electro-diffusion process induced by the imposed ionic strength gradient is simulated by solving Poisson-Nernst-Planck equations in a water film bound between two charged surfaces, using a finite...
Mechanistic Investigation of Enhanced Oil Recovery by Engineered Water Using Computational Fluid Dynamics at Pore Scale
, Ph.D. Dissertation Sharif University of Technology ; Ayatollahi, Shahaboddin (Supervisor) ; Mahani, Hassan (Supervisor)
Abstract
Despite the proven advantage of the engineered water flooding technique, a coherent and mechanistic understanding of the fundamental phenomena occurring at pore scale is lacking. Most of the available simulation models have a phenomenological approach and have limited predictive capability. One of the key questions is how to justify and relate large (Darcy) scale observations to effects and phenomena that essentially occur at much smaller scales (i.e. pore and molecular level). Furthermore, two-phase flow dynamics and the effect of complex interplay between wettability, capillary number, and ions dispersion in a heterogeneous porous medium on the trapping and mobilization of oil at pore...