Copyright by Zheng Xue 2015 The Dissertation Committee for Zheng Xue Certifies that this is the approved version of the following dissertation: Stability and Rheology of High Internal Phase CO2-in-Water Foams and Stability and Transport of Polymer Grafted Nanoparticles Committee: Keith P. Johnston, Supervisor John Ekerdt Chun Huh Kishore Mohanty Guihua Yu Stability and Rheology of High Internal Phase CO2-in-Water Foams and Stability and Transport of Polymer Grafted Nanoparticles by Zheng Xue, B.E. Dissertation Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin August, 2015 Dedication To my dearest Xiaodan Wei, and my beloved parents Meie Song and Weitang Xue, for their love, support and encouragement. Acknowledgements I am indebted to Professor Keith P. Johnston for his guidance, scrutiny and dedication throughout the course of this work. I am deeply grateful to be guided to the fascinating area of colloids and interface science, and the exciting projects for applications in oil & gas industry. His hard work and scientific contributions are invaluable to this dissertation. I wholeheartedly enjoyed the achievements we made as a team. I am also deeply grateful to all the help and mentoring from my committee members. I would like to thank Dr. Kishore Mohanty for his excellent graduate class of Reservoir Engineering, and his dedication, insight and encouragement; Dr. Chun Huh, Dr. Steve Bryant, Dr. John Ekerdt and Dr. Guihua Yu for their help, guidance and uncountable insightful discussions. I would also like to acknowledge all the help I received from my colleagues, in particular, the great mentorship from Dr. Hitesh Bagaria, Dr. Yunshen Chen, and Dr. Jiannan Dong; and the discussions and support from all the group members Amro Elhag, Yunping Fei, Will Hardin, Robert Stover, Andrew Worthen; and the experimental work of my undergraduate research advisees Victoria Cheng, Susheela Nayak and Robert Isaiah. v Stability and Rheology of High Internal Phase CO2-in-Water Foams and Stability and Transport of Polymer Grafted Nanoparticles Zheng Xue, Ph.D. The University of Texas at Austin, 2015 Supervisor: Keith P. Johnston In an effort to reduce the water consumption in hydraulic fracturing by using foam based fracturing fluids, the stability and rheology of ultra-dry supercritical CO2-in- water foams were investigated in terms of bulk phase viscosity, interfacial tension, and interfacial rheology. The foam morphology and long term stability was studied in situ with high pressure microscopy. Foams with up to 0.98 CO2 volume fraction and apparent viscosities of hundreds of centipoise were stabilized for hours to days by increasing the viscoelasticity of the interface and the continuous phase. The interfacial shear viscosity and compression elasticity were enhanced with either mixture of oppositely charged surfactant and nanoparticles (with and without high molecular weight polyelectrolyte) or viscoelastic surfactant alone which formed wormlike micelles. The increased interfacial viscoelasticity leads to a rigid foam film as characterized by high Boussinesq number and Marangoni number. Thus, the drainage of the foam film was suppressed due to the immobile interface and the high continuous phase viscosity, as described by the Reynolds drainage equation. The resulting thick film as well as the elastic interface decreases the rate for coalescence and Ostwald ripening. Consequently, foams with fine texture of ~20 µm bubbles were produced and stabilized for hours. vi Nanoparticles that can be transported through porous rock at high salinity and high temperature are expected to have a large impact on the wellbore diagnostics, electromagnetic tomography and enhanced oil recovery. A series of stable anionic and zwitterionic polymers in high salinity brine at high tempeartures were identified and synthesized. Furthermore, when covalently tethered to the nanoparticles via “grafting to” or “grafting through” approach, the obtained polymer grafted nanoparticles exhibited colloidal stability in high salinity brine for over 1 month, and also low static adsorption to silica microspheres at 1mg/m2. The silica microspheres were used to mimic mineral surfaces. The remarkable colloidal stability and low adsorption on mineral surfaces was attributed to electrosteric repulsion exerted by the charged and extended polyelectrolyte chains on the nanoparticle surface. vii Table of Contents List of Tables ...........................................................................................................x List of Figures ....................................................................................................... xii Chapter 1: Introduction ............................................................................................1 1.1 Motivation for ultra dry foams ..................................................................1 1.2 Background on the stability of foams .......................................................3 1.3 Motivation for the design of magnetic particle dispersions ....................11 1.4 Background on the colloidal stability at high salinity ............................12 1.5 Objectives ...............................................................................................13 1.6 Dissertation outline .................................................................................14 Chapter 2: Viscosity and Stability of Ultra-High Internal Phase CO2-in-Water Foams Stabilized with Surfactants and Nanoparticles with or without Polyelectrolytes .......................................................................................................................18 2.1 Introduction .............................................................................................18 2.2 Experimental ...........................................................................................22 2.3 Results and discussion ............................................................................27 2.4 Conclusions .............................................................................................49 Chapter 3: Ultra Dry Carbon Dioxide-in-Water Foams with Viscoelastic Aqueous Phases ............................................................................................................50 3.1 Introduction .............................................................................................50 3.2 Experimental ...........................................................................................55 3.3 Results and discussion ............................................................................60 3.4 Conclusions .............................................................................................76 Chapter 4: Iron Oxide Nanoparticles Grafted with Sulfonated Copolymers are Stable in Concentrated Brine at Elevated Temperatures and Weakly Adsorb on Silica .......................................................................................................................78 4.1 Introduction .............................................................................................78 4.2 Experimental ...........................................................................................81 4.3 Results and discussion ............................................................................86 viii 4.4 Conclusions ...........................................................................................106 Chapter 5: Effect of Grafted Copolymer Composition on Iron Oxide Nanoparticle Stability and Transport in Porous Media at High Salinity ..........................107 5.1 Introduction ...........................................................................................108 5.2 Experimental .........................................................................................111 5.3 Results and discussion ..........................................................................119 5.4 Conclusions ...........................................................................................136 Chapter 6: Iron Oxide Nanoparticles Grafted with Sulfonated and Zwitterionic Polymers: High Stability and Low Adsorption in Extreme Aqueous Environments ..............................................................................................138 6.1. Introduction ..........................................................................................138 6.2. Results and discussion .........................................................................140 6.3. Conclusion ...........................................................................................148 Chapter 7: Conclusions and Proposed Work .......................................................150 7.1 Conclusions ...........................................................................................150 7.2 Recommendations .................................................................................152 Appendices ...........................................................................................................154 Appendix A .................................................................................................154 Appendix B .................................................................................................155 Appendix C .................................................................................................167 Bibliography