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Friday 17 Mar 2017A License to Engineer

Tim Harper -

Harrison Building, HAR170 14:00-15:00


Engineered constructions, processes and operations require licenses. This usually involves regulatory bodies and any other interested parties, the latter representing the ‘social licence’. There can be a tendency amongst engineers to focus on satisfying the regulatory bodies without sufficiently careful attention to pre-empting any possibility of a negative public perception.

The seminar will contrast the licensing of two types of subsurface construction. The first of these activities concerns high-level nuclear waste (HLW) disposal, which is unprecedented. Such constructions must be safe for 104-105 years or more. In the early years, the waste is heat-emitting. There is no experience, thus no performance history available to statistically evaluate the risk of toxic material escaping to the biosphere. Exemplified by the US HLW disposal experience, a programme of site investigation typically takes decades with licensing a primary objective. Experiments to evaluate the safety can be conducted only at spatial and time scales which are very small compared to operating conditions and these tests are confined to isolated aspects of the coupled system. The second subsurface activity, hydraulic fracturing, is a means of completing an oil or gas well which involves the creation of a single crack in low permeability rock around a wellbore. Treating wells by hydraulic fracturing started as full-scale experimental trials with little concern for licensing and has since been practised for more than 65 years. Most of us have benefitted from the process, such as by heating our homes and cooking using the extracted fluids. The experience base is >106 hydraulically fractured wells. After more than 50 years of quiet progress, hydraulic fracturing has recently become a scapegoat or bÍte noir in the eyes of many. It has been banned in countries such as Scotland and France. Public opinion in England appears to be turning against the process. This may reflect a combined failure of both operators and government to pre-empt this threat, despite the extensive and largely successful experience base. Paradoxically, only trivial questions remain to be satisfied before the US HLW disposal site is licensed.

Tim Harper

Tim Harper has a PhD in rock mechanics for research in flow in fractured rock, and an MSc in Structural Geology and Rock Mechanics, from Imperial College. He has worked for a US consultancy, including on the foundations of a US nuclear power plant. He initiated and managed a technical service and research team concerned with the productivity of oil and gas wells for BP, later being involved in the engineering of an oil field in Colombia subject to active faulting. He was joint recipient of the Royal Academy of Engineering’s MacRobert award for engineering innovation in 1992 and has given a Friday Evening Discourse at the Royal Institution. After BP he formed a small geomechanical consultancy. Dr Harper is an Honorary Research Fellow of the university. His current research interests are hydraulic fracturing in shale and characterisation of the mechanical state of rock, including long-range interaction, stress history and stress memory.

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