Fundamental Understanding of Oil Adhesion Under Reservoir Conditions (FOilCon).

Growing global demand for oil, diminishing availability of conventional sources and increased sustainability criteria mean enhanced oil recovery (EOR) operations are increasingly deployed to extend reservoir life. This is especially true for mature UKCS fields, and BP has invested £120 million to deploy low salinity water EOR (Claire Ridge Field) to realise an additional 42M barrels of oil over the field life. Despite its increasing use, the geochemical basis of low salinity EOR is still not well understood. Oil wettability is linked to its "ability" to adhere to rock surfaces, which mainly occurs by the interaction of polar oil components with different mineral/grain surfaces. Therefore, understanding how EOR works requires a direct knowledge of the mechanisms controlling these interactions. To date most studies on the topic have been of an indirect nature, where a solution is flown over a core sample and different outputs are measured. More recently, chemical force microscopy (CFM) has been deployed to directly measure the adhesion between organic functional groups (representative of oil molecules) and mineral surfaces, but these measurements have been exclusively done at room temperature and pressure, in other words, well outside the conditions encountered in real reservoirs. This proposal seeks to alleviate this situation by designing, building and deploying a next-generation hydrothermal atomic force microscope (HAFM).

Atomic force microscopy (AFM) has proved to be a key technique in studying a wide variety of phenomena at the nanoscale. This is due to its extremely high vertical (below 1 Å) and lateral (5-10 nm) resolution and its ability to perform studies in solution. Therefore, the AFM can provide quantitative kinetic data at the scale of elementary reactions and also qualitative information on multitude of processes (dissolution, precipitation, etc). Chemical force microscopy is a derivative of conventional AFM, where the tip is functionalised with a specific functional group and then it's approached to a surface, allowing for the measurements of interaction forces, including adhesion. Currently, however, hydrothermal conditions are beyond the range of commercial systems and only a handful of custom systems can reach temperatures of 130 C. The main goal of this grant is to develop a next-generation hydrothermal AFM. The main characteristics of this system will be: 1) Ability to reach 180 C and 20 atm. 2) The addition of XY translation stage, opening the door to study sub-mm crystals. 3) State-of-the-art fluid delivery system and custom-made fluid cell to perform experiments at any pH range desired. Once built, the HAFM will be deployed to study mineral-oil interactions at the nanoscale by means of CFM.

Investigations in oil-mineral surface interactions will be carried out with different functionalised tips, representing a variety of functional groups (as present in crude oil), and will be carried out under solutions of different salinities with the goal of understanding the low salinity effect on reducing oil-surface adhesion.

The application of the proposed instrument can have wide ranging implications in the NERC's strategic research areas of Physics and Chemistry of Earth Materials, and Sediments and sedimentary processes. In addition, the new HAFM, will have a range of applications outside the NERC's remit as well as in industry.

The broader impact of the proposed work is based on the development of a unique UK-based scientific instrument. The capability of the HAFM to perform nanoscopic observations at high temperature/high pressure conditions will open the door for a wide range of studies, from fundamental to applied, and within and outside the realm of Earth Sciences and academia. During the duration of the grant the main beneficiaries will be the Earth Sciences Department and Durham University as well as industry collaborators and contacts (BP, Shell, Chevron, Conoco-Philips), three of whom have provided support letters to the project, and one is in progress. The impact on investigations related to Enhanced Oil Recovery operations will be more important to industry and may lead to a direct application that could benefit UK-based oil producers and consumers. Far reaching consequences of improved oil recovery operations within the UK and Northern Sea will be a decrease in the reliance of oil imports with economic and national security implications.

After the end of the grant, once the HAFM is fully operational, it will be available for use by other interested partners within the UK Earth Sciences community. Outside Earth Sciences, potential beneficiaries within the academic world, will be the materials science/chemistry communities, in fields such as, crystallisation, microporous solids and catalysis. Other research bodies, such as the British Geological Survey or the Atomic Energy Authority could also benefit from the use of the HAFM, in which case the research conducted will have broader and more immediate societal implications. Examples of possible research include dissolution and precipitation of materials used for radioactive waste immobilisation, dissolution and precipitation of CO2 sequestering minerals and development of mineral-based materials for industrial applications.

UK-based industries will also benefit from the use of the HAFM. An additional advantage from using the HAFM is its ability to perform experiments using aggressive (high/low pHs) conditions (and potentially gas environments with minor modifications) will be specially attractive for research-led industries. The list of potential industry beneficiaries could be as long as the types of companies working on materials and processes at hydrothermal conditions but a few examples are: the oil and gas industry, who could use the instrument beyond the proposed research on Enhanced Oil Recovery, as stated on their letters of support, for example to study the performance of materials used in drilling and oil recovery operations as well as in oil cracking and refining. The materials industry could benefit from performing experiments where temperature-related phase transitions are involved or where temperature degradation is of importance on a process, such as catalysis. Another important industrial application is the study of corrosion and scale formation in pipes. Here the potential beneficiaries could extend beyond the traditional oil and gas industry and extend to other fields in the energy sector such as hydrothermal power generation. Use of the HAFM could provide, in some instances, an advantage to UK-based companies over overseas competitors. Finally, additional societal impacts from the use of HAFM in industry will come from consumers benefiting directly from product improvement.