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Fundamental Studies to Enable the Environmentally Conscious Application of Hydraulic Fracturing in Shale Formations

Final Report Summary - FRACCINGFUNDAMENTALS (Fundamental Studies to Enable the Environmentally Conscious Application of Hydraulic Fracturing in Shale Formations)

Shale gas has enabled a transformation of the US economy, with the creation of jobs not only in the energy sector, but also in manufacturing. The latter has been possible via the availability of large amounts of natural gas. In addition to socio-economical benefits, shale gas in the US has led to significant reductions in the environmental footprint, because the availability of natural gas has allowed the substitution of coal-fired power plants with natural gas ones. However, the exploration and production of shale gas can also lead to several environmental risks. Of particular interest to the wide public are induced seismicity, large use of fresh water, fugitive emissions, as well as increased traffic and potential spills that could lead to environmental contamination.
The project fracking fundamentals focused on the fundamental physical phenomena that are related to the production of shale gas, and that could also potentially be responsible for environmental contamination. The project was instrumental for enabling Prof. Striolo to establish his research group within the Chemical Engineering Department of University College London. Prof. Striolo's group is currently made up of 6 full time PhD students, 1 part-time PhD student, and 2 post-doctoral researchers. Prof. Striolo also co-supervises two other post-doctoral researchers. Much of the research currently conducted within this group has been positively influenced by the Career Integration Grant 'Fraccing Fundamentals'. It is important to point out that, after being awarded this CIG in 2014, Prof. Striolo has become the coordinator of two Horizon 2020 research consortia: ShaleXenvironmenT, a 3M euro investment from 2015 to 2018, and Science4CleanEnergy, a 10M euro investment started in 2017. ShaleXenvironmenT had the goal of assessing the environmental impact of shale gas exploration and production, with focus on the European landscape. As such, the ShaleXenvironmenT consortium can be considered as the natural development of the 'fraction fundamentals' grant. Science4CleanEnergy extends the R&D activities to several sub-surface geo-energy operations, including unconventional hydrocarbons, geo-thermal energy and carbon sequestration. The progression in scope and investment is a manifestation of the success of the initial investment supported by 'fraccing fundamentals'. The websites for these projects are:
https://shalexenvironment.org
http://science4cleanenergy.eu
The project 'fraccing fundamentals' was not supported by a dedicated website because much of the research results it delivered was aligned with those of the two consortia just mentioned. However, Prof. Striolo's website is available at:
http://www.ucl.ac.uk/chemeng/people/academic-staff/alberto-striolo
The results achieved over the past 4 years target many stakeholders:
1. Wide public. Several outreach events were organised during the last 4 years. Of particular interest are (a) the 'Shaleology' forum (https://shalexenvironment.org/2018/10/31/shaleology-forum-2018/) and (b) the Summer Challenge 'Engineering Solutions from Nature' (http://science4cleanenergy.eu/the-summer-challenge-engineering-solutions-from-nature-2018-is-underway/). Shaleology has been a yearly event, which brought together experts from Europe, Australia and North America to discuss issues related with the environmental footprint of shale gas. Speakers represented academia, government agencies and the private sector. Attendees included from students, practitioners, general public, and scientists. The Summer Challenge brought to UCL up to 20 under-represented pre-university students each summer. The goal was to attract these students to entertain university degrees in STEM. Approximately 30% of the students who completed the Summer Challenge applied to UCL for their university education, which is considered a great success.

2. Industry. Prof. Striolo has become Deputy Head of the Chemical Engineering Department at UCL for Enterprise. As such, his role is to enhance contacts and collaborations between academia and industry. The success of the 'facing fundamentals' project, as well as that of the consortia ShaleXenvironmenT and Science4CleanEnergy allowed him to secure strong collaborations with industry in the energy sector. The research conducted in his group within the realm of the 'fraccing fundamentals' project has been instrumental, for example, to establish a 'Knowledge Transfer Partnership' with BP: one post-doctoral researcher, co-advised by Prof. Angelos Michaelides and Prof. Striolo, is transferring to BP the know how developed at UCL on how to study interfacial fluids of interest to unconventional hydrocarbons. Prof. Striolo has also been able to establish productive collaborations with Halliburton, in a project directly related to understanding fluid transport in shale formations.

3. Decision Makers. The development of technologies useful for the quantification of the environmental impact of shale gas is essential for providing information to decision makers. Prof. Striolo has established useful connections with the Environment Agency in the UK to ensure that the academic discoveries can have an impact on the society at large.

4. Future generations. In the last 4 years, Prof. Striolo has graduated 4 Ph.D. students, two of whom were trained in the general areas of interest to the 'fracking fundamentals' project. In addition, Prof. Striolo has trained numerous masters-level students, and has also introduced the post-graduate taught masters program 'Global Management of Natural Resources', which he now directs at University College London (https://www.ucl.ac.uk/prospective-students/graduate/taught-degrees/global-management-natural-resources-msc). This program now attracts ~25 students each year. The students learn about risks and opportunities related to a number of natural resources, including shale gas.

5. Academics. Prof. Striolo has been a prolific author, who has widely disseminated his research outputs. Since 2014 he has published over 40 peer-reviewed journal articles, many of which (15) directly related to the 'fraccing fundamentals' project. The results from some of these contributions are discussed in details below.

In the following the main research results are discussed. The results were presented in peer-reviewed journal articles, listed in Section A (Dissemination Measures). The numbers refer to those in Section A, where full bibliographic details are provided.

a. Reviews for the state of the art and suggestions for further studies (1, 5, 7, 10). In these papers, Prof. Striolo and his collaborators have outlined the current state of understanding regarding the behaviour of fluids confined in the narrow pores typically found in shale formations. The main reason for these studies is that it has become apparent that when fluid molecules are confined in pores that are of size comparable to a few times the molecular diameter, the fluid properties change significantly compared to those known for bulk systems. For example, liquids could become solids, mutual solubility between insoluble fluids could change, and transport properties change. All these effects become particularly important for shale gas production, as in shale formations many pores are of size comparable to that of fluid molecules. In these papers (1, 5, 7, 10), several fundamental questions were raised, and in particular the need of synergistically coupling experiments and computational studies for securing progress.

b. Transport mechanisms were discovered (2, 3, 5, 6, 8, 12, 13). In these papers Prof. Striolo and his group documented new mechanisms by which fluid mixtures can be transported within narrow pores. In some cases, it was found that one component of a mixture can preferentially adhere to the pore surface, acting as a 'molecular lubricant' for the other chemical components - this is important for developing new enhanced oil recovery strategies, for example. In other cases, it was found that water-water attractions are so strong that water can form 'molecular bridges' across the pore volume: when these bridges are perpendicular to the direction of imposed motion, transport can be reduced - this could explain why the productivity from shale formations fast decreases a few months after hydraulic fracturing is completed. In pores completely filled with water, Prof. Striolo was able, for the first time, to identify peculiar transport mechanisms for selected guest molecules (e.g. methane), and he developed a theoretical framework to describe such transport. As a whole, these results are important not only for shale gas production, but also for separations, catalysis, and other operations within the Chemical Engineering discipline.

c. Confinement effects on solubility were quantified (4, 15). Prof. Striolo reported that confinement can strongly enhance the solubility of methane in water, and decrease that of hydrogen sulphide in water. These fundamental studies were able to identify the molecular reasons for these observations (creation of nano-scale cages that can host methane and disruptions of the hydration shell around hydrogen sulphide, respectively), which is important for designing new membranes and separation processes. From the point of view of the environmental risks connected with shale gas, these results are important because they could be useful for predicting the transport of gases across long distances in the sub-surface.

d. Confinement effects on chemical reactions (9, 14). Using simulations, Prof. Striolo and his co-workers showed that it is possible that confinement shifts the equilibrium composition of the CO2 methanation reaction. The importance of this finding is due to the fact that it suggests the possibility that hydrocarbons can be obtained in the sub-surface without the need of organic sources. Experimental verifications are required to further test this intriguing possibility.

For further details, please contact Prof. Striolo at the Department of Chemical Engineering, University College London: phone +44 (0) 20 7679 3826; email: a.striolo@ucl.ac.uk