Re-purposing Hydrocarbon Wells for Geothermal Use in the UK: a Preliminary Resource Assessment

Abstract

This paper presents the findings of a research project funded by the EPSRC National Centre for Energy Systems Integration and supported by industrial partners. The use of geothermal energy for heating is increasing worldwide to meet demand and emissions targets. In the UK, heat represents ~50% of total energy demand. With summer 2018 being the joint hottest on record in the UK, geothermal cooling systems may also soon be in high demand. Agriculture is another heavy energy consumer and greenhouse gas emitter and is exposed to fluctuating energy prices; geothermal heating/cooling can play a key role in decarbonising this sector. Despite the potential of geothermal energy, the high technical and economic risk at the exploration stage limits development. One way to reduce this risk is to target well-characterised hydrocarbon reservoirs; this can also substantially reduce drilling costs. Although offshore hydrocarbon fields offer significant geothermal energy potential, it is likely that only electricity generation would be appealing in such remote environments and exclusively for in-project utilisation, unless interconnecting export grids become available. This study therefore focuses on onshore hydrocarbon fields. Around 2000 wells have been drilled onshore in the UK. There are currently 230 onshore Petroleum Exploration and Development Licenses and 120 sites with 250 operating wells. From this inventory, this study identifies the most favourable candidate sites for geothermal repurposing, taking into accountinfrastructure longevity issues of ageing/abandoned fields. It also discussed the current UK regulatory framework, which does not contemplate retrospective repurposing of hydrocarbon wells for geothermal use.