Repurposing Oil &amp; Gas Wells and Drilling Operations for Geothermal Energy Production

Pilko, Robert M.; Hart-Wagoner, Nicole Rita; Horn, A.J. Van; Scherer, Joseph A.

doi:10.4043/31090-ms

Cited by 4 publications

(1 citation statement)

References 21 publications

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“…By doing so, an existing asset is leveraged while also aiding in climate change mitigation. Several studies [15][16][17][18][19][20][21][22][23] have investigated the possibility of repurposing an existing borehole for geothermal heat extraction by using a closed-loop deep borehole heat exchanger (DBHE). According to [24], flow rate and geothermal gradient are key parameters in repurposing oil and gas wells for geothermal energy extraction.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2023

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

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Section: Introductionmentioning

confidence: 99%

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

et al. 2023

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Benefits and Risks of Geothermal Energy

kanna I

2024

Encyclopedia of Renewable Energy, Sustainability and the Environment

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Estimation of Geothermal Electric Power Production from Mature Oil Fields

Negre

Andjar

Muller-Shernetsky

et al. 2022

Day 4 Thu, November 03, 2022

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Geothermal energy development is of critical importance to meet the global challenge of energy transition. This work demonstrates that existing oil and gas industry tools can be used to evaluate the potential of geothermal energy production from mature oilfields using the heat contained in the produced fluids. This can contribute to a decarbonation strategy and be profitable since most of the costs (drilling, pumps…) are already supported by oil production operations. The only additional costs consist in surface facilities to convert thermal energy into electricity. The aim of the study is to evaluate the potential of a mature oil field to generate electricity and predict the evolution of energy potential with time considering the current development plan for the field. This plan was designed to maximize oil production in the field and did not consider possible electricity cogeneration from geothermal energy. The study was conducted in a sector of a mature oilfield including 15 producers currently producing about 10,000 barrels of liquid per day and with a 97% water-cut. A workflow was created to estimate the potential of electricity generation considering current and forecast liquid production rates, the nature of the secondary working fluid used in the Organic Rankine Cycle (ORC) and the minimum ejection temperature limits, defined by the operator, to avoid difficulties in surface separation processes. This paper describes the surface process used for thermal energy to electricity conversion, and presents the workflow used to estimate electricity generated from simulation results considering uncertainty tied to some fluids and rocks parameters.

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Repurposing Oil & Gas Wells and Drilling Operations for Geothermal Energy Production

Cited by 4 publications

References 21 publications

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

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

Benefits and Risks of Geothermal Energy

Estimation of Geothermal Electric Power Production from Mature Oil Fields

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