Novel Applications of Nanoparticles for Future Enhanced Oil Recovery
Authors: Bennetzen Martin Vad , Mogensen Kristian 
Published: May 2016

Abstract
During the last decades nanotechnology has proven to be applicable to a variety of different technological and research areas such as material design, biomedicine and electronics. The cross disciplinary research during the past decade has also revealed that nanotechnology possesses great promise for enhanced oil recovery applications.
Nanoparticles are small particles characterized by a diameter of 1–1000 nm and a very large area-to-volume ratio where the surface can be modified by conjugation or grafting to various kinds of molecules. Moreover, the material of the nanoparticle core can be selected to obtain specific physical properties. One example here of is to design nanoparticles of a super-paramagnetic material to enable flow manipulation via an external magnetic field. The fact that ultra-small nanoparticles can flow through narrow pores and pore-throats and that core/surface properties can be modified for a specific purpose via standard chemistry, makes them ideal candidates for various EOR applications. Consequently, research related hereto has been steadily intensified.
In the present paper we present a thorough review of the current research and development within the field of nanotechnology-based EOR, where nanoparticles are used to target various aspects of EOR processes. For instance nanoparticle-based EOR approaches have been developed to promote wettability alteration, viscosity reduction of oil, stabilization of foam or emulsions and interfacial tension reduction – in some cases involving application of an external electric or magnetic field. Nanoparticles have likewise been developed for flow assurance and well performance improvement by e.g. inhibiting hydrate and wax deposition. Finally, nanoparticles have shown potential in upstream applications and reservoir characterization (e.g. nano sensors).
Based on an extensive, critical and in-depth review of technical papers we will discuss opportunities and challenges, e.g. related to environmental issues, associated with nanoparticle-based EOR applications for the oil and gas industry. Moreover, we will provide a practical framework for designing tailor-made nanoparticles for targeted applications for the oil and gas industry by means of surface chemistry and superparamagnetic properties of nanoparticles.

Introduction
Innovation in oil exploration and enhanced oil recovery (EOR) technologies will be required to meet future demand of hydrocarbon fuels, and hence the O&G industry will inevitably have to focus on development of new technologies to increase the oil recovery of currently producing reservoirs as well as unconventional oil and gas resources – via research and technological innovation. Nanotechnology and nanoparticles provides a promising approach to such innovation.
Nanotechnology and applications of nanoparticles have revolutionized different sciences and industries and it possesses significant potential in the oil and gas industry as well in the fields of EOR, exploration, drilling fluid design, molecular separation, refining, water treatment etc. which we will describe below. The significant advantage of nanoparticles is that they can be tailor-made in a flexible manner using combinatorial chemical approaches and provides therefore an approach to transcend the current EOR technology.
In this paper we will describe different applications of NPs and notably also present concepts developed at Maersk Oil Research and Technology Centre based on which numerous patent applications have been filed.