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Theoretical and Experimental Investigation of Interaction between Nanoparticles and Carbonate Porous Media

Dehghan Monfared, Abolfazl | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 49215 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghazanfari, Mohammad Hosseini; Jamialahmadi, Mohammad; Helalizadeh, Abbas; Kazemeini, Mohammad
  7. Abstract:
  8. In recent years, application of silica nanoparticles for wettability alteration of reservoir rocks as an effective approach in enhancing oil recovery from petroleum reservoirs is introduced. However, in this area, lack of fundamental studies to provide a clear understanding about the interaction between these nanoparticles and carbonate rocks (as the predominant reservoir rocks in the world and Iran), which is of particular importance, is sensed. Therefore, the main purpose of this dissertation is to present a mechanistic investigation about the interaction of silica nanoparticles (the most used nanoparticles) with carbonate rock from theoretical and experimental viewpoints. To better understand the involved process, the interaction is evaluated in two conditions of presence/absence of oil. In this regard, the studies are divided into four main parts as: the investigation of static interaction, dynamic interaction, wettability alteration mechanism, and prediction of wetting condition from surface forces. In the first part, an experimental and theoretical study on the amount, possibility, mechanism and nature of silica nanoparticles adsorption onto calcite surfaces is presented. Moreover, to better understand the process in different situations, the interaction energies of particles are calculated using DLVO theory. In dynamic interaction studies, the effect of some parameters; i.e. nanoparticles concentration, flowrate and electrolyte; on the retention of particles in porous media during the nanofluid injection is investigated. Then, the experimental data are simulated by a suitable mathematical model. In the third part, the potential of silica nanoparticles for wettability alteration of oil-wet calcite is evaluated through contact angle measurements. In addition, on the basis of equilibrium and interaction studies for different ions/species presented in the nanofluid-calcite system, a mechanism for wettability alteration is proposed and verified by different tools. In the last part, a small scale study on the relation between wettability and surface forces are presented. This relation is usually described by Frumkin-Derjaguin model in which DLVO theory is utilized for calculating disjoining pressure isotherms. However, preliminary evaluation revealed that application of this theory is not enough for contact angle prediction. To improve the prediction of wettability in the abovementioned system, DLVO theory is modified with a suitable term. Results of static interaction studies revealed that the adsorption of silica nanoparticles onto calcite surface occurs in an endothermic phenomenon and a monolayer coverage is supposed to be predominant. Moreover, it was shown that in addition to intraparticle diffusion, the boundary layer diffusion mechanism contributes in the adsorption process. From electrokinetic investigation and DLVO interaction energy profiles, an unfavorable attachment condition was deduced in which the charge heterogeneity and presence of a secondary energy minimum is responsible for adsorption. In the second part, it was shown that the dynamic adsorption (retention) of silica nanoparticles during transport of nanofluids in the porous media is increased with the increase in nanoparticles concentration or ionic strength and decrease in flow rate. The effect of two earlier parameters is attributed to the increase of chemical potential and the role of hydrodynamic forces in the boundary layer, respectively. The role of later was justified by DLVO theory. Moreover, in this part, the experimental data from dynamic adoption tests was simulated by the addition of a filtration term to so called advection-diffusion equation. To find an appropriate filtration term, on the basis of pervious findings and evidences for adsorption behavior and mechanisms, a two-site adsorption model was proposed. In the third part, the responsible mechanism for wettability alteration was suggested to be the partial release of stearates from oil-wet calcite and their replacement with silica nanoparticles. This mechanism was proposed based on the evaluation of the interaction between ions/species presented in nanofluid-calcite system. Equilibrium reaction calculation provided useful information about the species distributions and determination of the most dominant ions and their performance in the process. The mentioned mechanism was further confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy visualizations. In the fourth part, to improve the prediction of wettability using Frumkin-Derjaguin model, following a surface force analysis, it was concluded that the incorporation of hydrophobic structural interaction in the total disjoining pressure isotherm increased the accuracy of modeling process. This contribution is introduced by considering the hydrophobic forces for an average hydrophobicity assumption on the surface as well as a combination of hydrophobic/hydrophilic forces for different sites covered by stearates/silica nanoparticles. Both approaches resulted in a good agreement between the model and experimental results
  9. Keywords:
  10. Mechanism ; Interaction ; Wettability ; Silica Nanoparticles ; Carbonated Rock ; Structural Forces ; Derjaguin-Landau-Verwey-Overbeek (DLVO)Theory

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