Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues

Westaway, Rob

doi:10.1144/qjegh2016-016

Cited by 8 publications

(7 citation statements)

References 60 publications

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“…The geothermal potential of hydrocarbon wells has been investigated by several authors, with pilot projects implemented worldwide and pre-feasibility studies carried out (e.g., [18][19][20][21][22][23][24]). Although offshore hydrocarbon fields offer geothermal energy potential (e.g., [19,23,25]), 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 (e.g., from Iceland).…”

Section: Repurposing Hydrocarbon Wells and Technology Optionsmentioning

confidence: 99%

Repurposing Hydrocarbon Wells for Geothermal Use in the UK: The Onshore Fields with the Greatest Potential

2020

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One potential opportunity for the decarbonisation of heat supply in the UK is the repurposing of onshore hydrocarbon wells for the production and/or storage of geothermal heat. This paper reports an investigation into the most favourable candidate sites for such repurposing, taking into consideration the available thermal energy outputs and technological options for heat use. A GIS mapping model was generated, combining public domain data on onshore wells and production data from onshore fields, provided by the UK Oil and Gas Authority, with available subsurface temperature data. This model has thus integrated information on location, depth, operational status, and bottom-hole temperature for onshore hydrocarbon wells with production rates from onshore fields in the UK. Of the 2242 onshore hydrocarbon wells thus reported, 560 have the potential to be repurposed, 292 of which are currently operating. Using aggregated water production data for all operating wells in each field, the fields with the greatest potential for geothermal repurposing are ranked. Two of these, the Wytch Farm and Wareham fields, are selected for more detailed analysis. Wytch Farm, the largest onshore oilfield in western Europe, produces water at ~65 °C that might yield a feasible thermal power output of ~90 MW. If an end use could be found where it might substitute for burning of natural gas, the value of this output would be ~£90,000 per day or ~£30 million per year. However, this field is located in a protected landscape where local development would be restricted by planning regulations. The Wareham field is not in a protected landscape, but the low temperature, ~44 °C, and low flow rate limit the scope of potential end uses. Nonetheless, these and the other highly ranked fields have potential heat outputs that are significant compared with other geothermal heat projects, thus offering the possibility of making useful contributions to the decarbonisation of UK energy use.

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Section: Repurposing Hydrocarbon Wells and Technology Optionsmentioning

confidence: 99%

Repurposing Hydrocarbon Wells for Geothermal Use in the UK: The Onshore Fields with the Greatest Potential

2020

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“…TS can be estimated as ~10 °C and , c and  as ~1000 kg m -3 , ~4186 J kg -1 °C -1 , and ~0.45 mPa s, respectively, so qB was ~1.7 l s -1 but D was not specified. Westaway (2016) estimated D as ~40 mm from a photograph of the pipe used in this prototype test, which implies V ~1.4 m s -1 , suggesting Re ~120,000. The flow was thus highly turbulent; from Moody (1944) for very smooth pipe fD would be ~0.018.…”

Section: Produced Water Treatment and Associated Costsmentioning

confidence: 92%

Deep Geothermal Single Well heat production: critical appraisal under UK conditions

Westaway

2018

QJEGH

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The idea of Deep Geothermal Single Well (DGSW) heat production has existed for many years, but with no consensus regarding its potential applicability: proponents have made claims regarding thermal outputs that appear exaggerated, whereas detractors have stated that the concept can never be economic unless the capital cost of drilling has already been discounted. However, because this technology offers the potential of delivering geothermal heat projects 'off the shelf' with a minimum of site-dependent research, the possibility exists of achieving cost-effective solutions. The present study sets out to investigate this topic subject to environmental and subsidy regimes applicable in the UK; the results might also be useful for other jurisdictions. Under these conditions, the variant of the technology with greatest potential for cost effectiveness is the hcDGSW, or conductive DGSW with heat production via heat pump. Analytic modelling enables the physics of the heat-exchange processes within a hcDGSW to be approximated. It is thus established that this option can indeed be cost-effective under the current UK subsidy regime for deep geothermal heat, provided boreholes are deep enough and in localities where the geothermal gradient is high enough. The environmentally optimum operational mode (optimizing savings in CO2e emissions) involves heat production at a lower rate than the economically optimum mode (maximizing profit). If such projects are subsidized from public funds, then a particular operational mode might be specified, maybe as a compromise between these optima. After the 20 year duration of the subsidy, the technology might well no longer be economic, but the infrastructure might be easily repurposed for seasonal heat storage, thus offering the potential of making a significant long-term contribution to sustainable future heat supply. These preliminary results indicate that more detailed appraisal of this technology variant is warranted. Introduction Most deep geothermal heat production projects are based around the concept of well doublets, in which production of thermal water from one well is balanced by injection of the water (after heat is supplied from it to the heat load) in a second well. The injection of water serves two purposes: it avoids the drawdown in hydrostatic pressure that would result in the geothermal reservoir rocks if only a production well were in operation; it also avoids the need for treatment of the produced water before surface disposal, which in many circumstances would otherwise be necessary. Typically one or both of the injection and production wells are deviated so they reach the geothermal reservoir some distance (up to ~2 km; e.g., Smit, 2012) apart. Over time a project of this type gradually extracts heat from the reservoir rocks surrounding the production well; heat production usually takes place far faster than the associated 'thermal recharge' by upward heat flow from the Earth's interior. The cold thermal front emanating from the injection well will therefore eventuall...

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“…Robert Gordon University in Aberdeen which uses 66 boreholes of 200 m depth to balance such interseasonal cooling and heating demand (Singh et al, 2019). Future research has to reveal if the Midland Valley geology is suitable for heat storage, but the use of redundant onshore hydrocarbon wells for heat storage could reduce construction costs significantly (Westaway, 2016).…”

Section: Heat Storagementioning

confidence: 99%

Low-carbon GeoEnergy resource options in the Midland Valley of Scotland, UK

Heinemann

Alcalde

Johnson

et al. 2019

SJG

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Scotland is committed to be a carbon-neutral society by 2040 and has achieved the important initial step of decarbonising power production. However, more ambitious measures are required to fully decarbonise all of the electricity, transport and heating sectors. We explore the potential to use the low-carbon GeoEnergy resources and bio-energy combined with Carbon Capture and Storage (BECCS) in the Midland Valley area to decarbonise the Scottish economy and society. The Midland Valley has a long history of geological resource extraction, and as a result, the geology of the region is wellcharacterised. Geothermal energy and subsurface energy storage have the potential to be implemented. Some of them, such as gravity and heat storage, could re-use the redundant mining infrastructure to decrease investment costs. Hydrogen storage could be of particular interest as the Midland Valley offers the required caprock-reservoir assemblages. BECCS is also a promising option to reduce overall CO 2 emissions between 1.10-4.40 MtCO 2 /yr. The Midland Valley has enough space to grow the necessary crops, but CO 2 storage will most likely be implemented in North Sea saline aquifers. The studied aspects suggest that the Midland Valley represents a viable option in Scotland for the exploitation of the majority of low-carbon GeoEnergy resources.

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Repurposing of disused shale gas wells for subsurface heat storage: preliminary analysis concerning UK issues

Cited by 8 publications

References 60 publications

Repurposing Hydrocarbon Wells for Geothermal Use in the UK: The Onshore Fields with the Greatest Potential

Repurposing Hydrocarbon Wells for Geothermal Use in the UK: The Onshore Fields with the Greatest Potential

Deep Geothermal Single Well heat production: critical appraisal under UK conditions

Low-carbon GeoEnergy resource options in the Midland Valley of Scotland, UK

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