Crude Oil Adsorbates on Calcite and Quartz Surfaces Investigated by NMR Spectroscopy

Abstract

The research presented here is part of a larger research project named "Wetting in porous media, a multi method approach to measurement, imaging and modelling". The main focus in papers 1-4 has been to study mechanisms responsible for wettability alteration on reservoir minerals and then to study how surface wettability affects the distribution of immiscible fluids in porous media. Nuclear Magnetic Resonance (NMR) has been the main analytical tool. The thesis consists of two parts. Chapters 1-5 contains an introduction to the field, the theoretical concepts behind the research, the applied methods and materials, the main results and the conclusions drawn from this work. The second part contains the research papers that were published as a result of the work presented in this thesis. Papers 1-4 can be found after the bibliography. i I would like to acknowledge the excellent guidance provided by John Georg Seland. His teachings, his patience and in general his supervision has been second to none. I would also like to thank my co-supervisors Willy Nerdal and Per Fotland for their professional input when needed. When I started this project I had never operated an NMR spectrometer. I would therefore like to thank the rest of the NMR group at the Department of Chemistry as well (NilsÅge, Josè, Jarl, Olav and Christian) for including me and for advices along the way. I would like to give a special thank you to Christian for the way he taught me how to operate the spectrometers. The Department of Chemistry at the University of Bergen will always be a special place for me. Yes, it was the place i went to school for nearly a decade, but it was also the place where i met my fiancè. I was sitting in that office both when I was told that the bid on our first house was accepted and I was sitting there when Sarah Marie called to tell me that i had to come home because it was time to go to Haukeland to meet our son. My dearest Sarah Marie, the finishing touches on this thesis has been applied during weekends and during the late hours of the night, which I know has put extra responsibility on you. Thank you so much for your continued support and patience throughout this entire process. This would have been impossible without you. My dearest Eiliv, you are currently too young to realize that I have been working when I should have been with you. I promise that will change now. This is for you.

Chemical Composition and Structure of Adsorbed Material on Pore Surfaces in Middle East Reservoir Rocks

“…In a recent study, Ataman et al demonstrated, using density functional theory (DFT) and XPS in a study with pure calcite, that carboxylate interacts more strongly with calcite than alcohols, water and aldehydes, and that the presence of side groups on these molecules influences their adsorption behavior. Our results are in excellent agreement with that work and with the results of a more recent NMR investigation of crude oil adsorbates on calcite, where carboxylate adsorption was demonstrated to be responsible for wettability alteration …”

Wettability Alteration and Enhanced Oil Recovery Induced by Proximal Adsorption of Na+ , Cl− , Liu1, Wani2, Alhassan3 et al. 2018Phys. Rev. Applied515270View full textAdd to dashboardCite

“…MD simulations confirmed that alcohols with molecular mass greater than that of methanol could displace water at the calcite surface [49,50]. Also, recent experiments showed that organic acids adsorb directly onto the calcite surface [51]. In the oil-wet initial state, since oil contacts the calcite surface, ions solvated in brine do not necessarily contact the oil phase (see the schematic diagram in Fig.…”

Debunking the Impact of Salinity on Crude Oil/Water Interfacial Tension

“…A principal surface-active material within the crude oil phase has been reported to be asphaltenes that can diffuse into the oil/water interface and form a rigid solid-like interface. , Formation of a rigid interfacial film by asphaltenes at the oil/water interface has been recognised as the main mechanism of stable water in crude oil (W/O) emulsions. Also, asphaltenes can diffuse into the oil/water interface and decrease the oil/water interfacial tension through interacting with the water molecules. , Carboxylic acids are distinctive surface-active materials inside the crude oil with the ability to diffuse into the oil/water interface and decrease the interfacial tension. , Formation of the lamellar liquid crystalline phase at the oil/water interface has been suggested as the mechanism of stable W/O emulsions by carboxylic acids. − Moreover, asphaltenes and carboxylic acids were reported as the main compounds of crude oils affecting the initial wettability state of the oil reservoirs after the migration of the oil from the source rock. − Thus, proposing methods to remove these surface-active materials (asphaltenes and carboxylic acids) from the rock surface leading to wettability improvement would be desirable, as it would improve oil recovery.…”