Shallow geothermal energy recovery and storage monitoring using Distributed Fibre Optic Sensing (DFOS) systems– UK Geoenergy Observatories, in Glasgow and Cheshire, UK

Abstract

The transition to renewable energies requires adaptation of existing technologies and the development of new techniques. Geothermal energy could play an important part in the development of “green” energy industries for climate change mitigation and diversification of energy sources. Distributed fibre optic sensing (DFOS) solutions provide flexible, multi-parameter measurements for the exploration and exploitation of the full range of geothermal resources, from shallow borehole, ground source heat to hydrothermal geothermal projects and Enhanced Geothermal Systems (EGS). The UK Geoenergy Observatories are new national facilities for research and innovation in shallow geothermal energy recovery and storage with field test sites in Cheshire and Glasgow, UK.  The Glasgow Observatory facilitates collaborative research to improve understanding of subsurface processes, environmental and induced change related to mine thermal energy storage (MTES). It provides scientific and engineering infrastructure for investigating the shallow, low-enthalpy geothermal energy and thermal storage resources available in abandoned and flooded coal mine workings which underly up to 25% of UK settlements. Borehole monitoring capability includes composite fibre-optic cables for distributed temperature and acoustic sensing (DTS & DAS) behind casing, for passive monitoring or for performing heat pulse tests in active mode, as well as ERT sensors for measuring geoelectrical properties in the wells and surrounding rock mass.  The Cheshire Observatory enables testing, monitoring and quantification of subsurface heat transfer processes, ground behaviour, thermogeology and hydrogeology, providing insights into sustainable operational management and maintenance requirements. The Cheshire Observatory comprises 20 instrumented boreholes drilled to 100m below ground level in the Chester Formation of the Sherwood Sandstone Group aquifer, with associated surface control, monitoring and data management systems. The installed fibre optic monitoring capability includes passive and active DTS, DAS and an advanced heat pulse controller serving multiple boreholes. Here we present an overview of the fibre optic sensing capability deployed at the Glasgow and Cheshire Observatories. Further information on the Glasgow and Cheshire Observatories is available online at: www.ukgeos.ac.uk. To discuss access or ideas for field experiments please contact BGS at:  ukgeosenquiries@bgs.ac.uk