Investigating the impact of deep groundwater flow on closed-loop geothermal systems, with direct application to repurposed infrastructure
Supervisor: Dr Christopher S Brown and Dr Isa Kolo
School: Engineering
Industry Partner: Dr Sean Watson, Senior Engineer Geologist at TownRock Energy
Description:
Geothermal resources have the potential to aid in decarbonisation of heat in the UK, specifically through the exploitation and low-cost repurposing of existing infrastructure, such as hydrocarbon wells. Therefore, through novel, innovate solutions these past carbon producing assets can be turned into carbon reducing assets in an attempt to curb emissions.
In this study, the repurposing of hydrocarbon wells as deep coaxial borehole heat exchangers (DCBHEs) will be explored with the purpose of contributing a low-cost, carbon neutral, heat source to nearby surface demand. DCBHEs operate through circulating fluid in a closed-loop system consisting of two concentric pipes. Cold fluid is circulated within the annulus, exchanging heat through conduction of the borehole wall with subsurface, warming with depth, before being advected to the surface.
The study will develop detailed numerical models of DCBHEs, incorporating a fully heterogeneous subsurface geological model, focusing on the repurposing of the 3 km deep Knutsford-1 borehole in the Cheshire Basin. This is an ex-exploration well, providing further novelties associated to deep, regional groundwater flow and how this will impact any geothermal operation. This will present unique opportunities to characterise the influence of groundwater flow on closed-loop systems and evaluate if they can i) prolong the resource lifetime, b) enhance thermal performance and c) help establish optimal production conditions. Minimal research has been undertaken in past studies on such systems with a dominant regional groundwater system at depth.
Work in this internship will be undertaken on OpenGeoSys, paraview, MATLAB, QGIS, among other software. Training will be provided by supervisors who have strong expertise in the matter. Further support will be provided by co-supervisor Sean Watson of TownRock Energy (TRE) who is a leading expert in characterising hydrocarbon wells for repurposing as geothermal assets. TRE are currently involved in investigating the potential for deep geothermal projects across the UK, including the Cheshire Basin; therefore, there is an opportunity for the research output to inform best practices adopted in industry and to further the knowledge base of the use of DCBHEs in the UK. The work from this study is also expected to contribute to publications and presentations.
Relevant publications:
Watson et al., 2020. Repurposing hydrocarbon wells for geothermal use in the UK: The onshore fields with the greatest potential. Energies.
Brown et al., 2023. Investigating scalability of deep borehole heat exchangers: Numerical modelling of arrays with varied modes of operation. Renewable Energy.