Effect of Hydrophobic and Hydrophilic Metal Oxide Nanoparticles on the Performance of Xanthan Gum Solutions for Heavy Oil Recovery.

Laura Corredor,Maen Husein,Brij Maini

doi:10.3390/nano9010094

Abstract

Recent studies revealed higher polymer flooding performance upon adding metal oxide nanoparticles (NPs) to acrylamide-based polymers during heavy oil recovery. The current study considers the effect of TiO2, Al2O3, in-situ prepared Fe(OH)3 and surface-modified SiO2 NPs on the performance of xanthan gum (XG) solutions to enhance heavy oil recovery. Surface modification of the SiO2 NPs was achieved by chemical grafting with 3-(methacryloyloxy)propyl]trimethoxysilane (MPS) and octyltriethoxysilane (OTES). The nanopolymer sols were characterized by their rheological properties and ζ-potential measurements. The efficiency of the nanopolymer sols in displacing oil was assessed using a linear sand-pack at 25 °C and two salinities (0.3 wt % and 1.0 wt % NaCl). The ζ-potential measurements showed that the NP dispersions in deionized (DI) water are unstable, but their colloidal stability improved in presence of XG. The addition of unmodified and modified SiO2 NPs increased the viscosity of the XG solution at all salinities. However, the high XG adsorption onto the surface of Fe(OH)3, Al2O3, and TiO2 NPs reduced the viscosity of the XG solution. Also, the NPs increased the cumulative oil recovery between 3% and 9%, and between 1% and 5% at 0 wt % and 0.3 wt % NaCl, respectively. At 1.0 wt % NaCl, the NPs reduced oil recovery by XG solution between 5% and 12%, except for Fe(OH)3 and TiO2 NPs. These NPs increased the oil recovery between 2% and 3% by virtue of reduced polymer adsorption caused by the alkalinity of the Fe(OH)3 and TiO2 nanopolymer sols.

Highlights

Water-soluble polymers have been used in enhanced oil recovery (EOR) due to their ability to improve sweep efficiency by controlling water mobility, reducing water permeability in swept zones and contacting unswept zones of the reservoir [1]
The performance of all nanopolymer sols was evaluated by conducting heavy oil recovery tests in linear sand-packs
The colloidal stability of the NPs dispersed in DI water and Xanthan gum (XG) solution was evaluated by the ζ-potential measurements

Summary

Introduction

Water-soluble polymers have been used in enhanced oil recovery (EOR) due to their ability to improve sweep efficiency by controlling water mobility, reducing water permeability in swept zones and contacting unswept zones of the reservoir [1]. Hydrolyzed polyacrylamide (HPAM) and xanthan gum are the most commonly used polymers for EOR [2]. Xanthan gum (XG) is a high molecular anionic polysaccharide produced by bacterium Xanthomonas campestris during the fermentation of a cellulosic backbone [3]. XG solution properties have been studied over the past 50 years. XG exhibits two conformational states: an ordered helix conformation and a disordered coil conformation [13]. The conformation of the XG molecules depends on the ionic strength of the solution and the temperature. In the presence of salts, XG molecules adopt a rigid rod like structure (ordered conformation) because the negatively charged pyruvate molecules wrap

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