Repurposing a Geothermal Exploration Well as a Deep Borehole Heat Exchanger: Understanding Long-Term Effects of Lithological Layering, Flow Direction, and Circulation Flow Rate

In the drive to achieve net-zero carbon emissions, decarbonisation of heating is essential. This can be facilitated by geothermal energy, but drilling wells associated with high risks and costs. The use preexisting (e.g., exhausted hydrocarbon or failed exploration boreholes) offsets this cost while potentially turning liabilities into assets. Newcastle Science Central Deep Geothermal Borehole (NSCDGB) a well that was drilled target Carboniferous Fell Sandstone Formation at 1418.5 1795 m depth. However, low hydraulic conductivities prevented development as conventional “wet” abstraction well; therefore, new alternative methods are being explored. work investigates repurposing NSCDGB deep borehole heat exchanger (DBHE), focusing on sustainable operation system in long term employing constant load designed contribute local buildings network. Numerical modelling undertaken using OpenGeoSys software analyse thermal performance system. Both homogeneous heterogeneous models were developed compare influence lithological layering contrast (nonstratified) subsurface geological model. Results from simulations DBHE depth 922 show 50-kW supported for lifetime 25 years. corresponds 65-kW building when coupled pump coefficient 4.33. Thus, could meet up 72% demand adjacent urban sciences building. Rather than purely hypothetical case study, considers real existing borehole, cluster which make heat. Heterogeneity, has been considered first time site, exhibits minor impact comparison simulation results. Flow direction mass flow rate also exhibited small effects performance, whereas if repurposed increased depths, increased. study coaxial site considering long-term rate, heterogeneity, direction. evaluates feasibility an exploratory UK used low-carbon source space heating, thus converting potential “green energy”