Dr Olivia Milton-Thompson
Job: Project Geochemist
Employer: SLR Consulting
PhD Thesis: Developing a risk assessment model using fuzzy logic to assess groundwater contamination from hydraulic fracturing
PhD Supervisors: Professors Akbar Javadi and Zoran Kapelan
Hydraulic fracturing is a viable method for extracting a wealth of natural gas from shale rock and has recently begun production in the UK. The process took off in the US but brought with it controversial debates over environmental protection. To feel confident in applying this technique to an apprehensive population in the UK, it is important to consider the science and engineering involved in the process. This project focuses on assessing the risks to groundwater contamination to help determine if the process is sufficient for use in the UK and the most suitable locations.
The project highlights the potential contaminant pathways for gas reaching aquifers during the stages of an active well’s life. These pathways are developed from conceptual models and quantified using event tree analysis. The over-arching theme has focused on well integrity issues during well stimulation and production. The event tree branches are quantified using failure probability values from literature, fuzzy logic inputs for geological and well construction properties and fuzzy fault tree analysis. Fuzzy fault trees are developed using expert knowledge to understand cement failure in a gas well over time. Expert opinions were gathered from academics and industry in Canada. The event tree branches leading to contamination are quantified to obtain a probability of contamination. A fuzzy inference system is developed to understand the changes in risk to groundwater for a producing well using a mathematical model developed on the understanding of gas migration during well integrity failure. The risk model is built and validated using well data and expert opinions from British Columbia, Canada. Final discussions focus on how this can be applied to a UK context.
In September 2018, Olivia spent 3 months at the University of British Columbia (UBC) in Canada working within the Energy and Environment Research Initiative (EERI) under Dr Aaron Cahill and the BC Oil and Gas Commission (BCOGC). She collaborated with MSc and PhD students within the EERI group to improve understanding of gas migration and well construction; academics within the mechanical engineering departments to develop cement failure fault trees; and Dr Laurie Welch at the BCOGC to obtain data from wells in BC. Canada is the main case study for her research project.
Olivia obtained her BSc from Durham University in Chemistry and her MSc from Cranfield University in Environmental Water Management. A dissertation was undertaken at Durham University in aromatic trifluoromethylation and the MSc thesis at Cranfield focused on the application of barley straw to reduce algal growth in reservoirs.
Before undertaking the MSc, Olivia worked as a laboratory analytical chemist at Huntingdon Life Sciences focusing on analytical methods such as LCMS, GC and HPLC. A summer placement as a research assistant at the University of Nevada, Reno in the Environmental Chemistry department ensured her interest in hydraulic fracturing where Olivia undertook work on inorganic contamination from fracking from the Pennsylvania Wells in the USA.
Keywords: Hydraulic fracturing, groundwater contamination, fuzzy logic, fault tree analysis, event tree analysis, risk assessment.
WISE 2017 Summer School Presentation: Olivia_Milton-Thompson_Jun17
June 2017 Poster: Olivia Milton-Thompson Jun17