With the right geology, design, and maintenance, geothermal wells for district heating can last for decades – making them a secure, long-term asset in the transition to low-carbon heating.
Why lifetime matters
For municipalities, utilities, and investors, one of the first questions about geothermal district heating is: How long will the wells last?
The answer is important because drilling wells is one of the largest CAPEX items in a geothermal project, so a long lifetime directly improves the return on investment.
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Typical lifespan of geothermal wells
With proper design, execution, and maintenance, production and reinjection wells in geothermal district heating can operate for 30 years or more. Some systems – like those in the Paris Basin, France, and Thisted, Denmark – have been in continuous operation for over 35 years, with wells still performing reliably.
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What determines a well’s lifetime?
Several factors influence how long geothermal wells remain productive:
- Geological conditions
- Stable, permeable reservoirs with benign water chemistries are less prone to problems such as scaling or pressure loss.
- Consistent injection temperatures and pressure conditions support stable output over decades.
- Well design and construction
- Correct casing, cementing, and material selection prevent corrosion and wellbore collapse.
- Screens or perforations are designed to maximise flow while preventing sand or debris ingress.
- Operation and maintenance
- Reinjection of cooled water maintains reservoir pressure and temperature.
- Regular maintenance — such as cleaning pumps, removing scale, and monitoring chemistry — extends well life.
- Monitoring and early intervention
- Continuous measurement of temperature, flow rate, and pressure helps detect changes early.
- Minor issues caught early are easier and cheaper to fix than major failures.
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When wells need intervention
Even with good management, wells may require workovers after 10–20 years to restore performance. This can include:
- Removing scaling from well screens.
- Re-lining or re-casing sections of the well.
Such interventions are routine and typically extend the operational life of the well significantly.
Furthermore, replacement of the electrical submersible pump (ESP) in the production well should be expected every 3-5 years.
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The bigger picture – system lifetime
While wells are long-lived, other parts of the geothermal system – such as surface heat exchangers, pumps, and heat pumps – have their own lifespans, usually 20–40 years depending on the component. Coordinated replacement planning ensures that wells and surface equipment continue to work seamlessly together.
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Examples of long-lived wells
- Paris Basin, France – Multiple wells still operating after more than 35 years, thanks to careful reinjection and monitoring.
- Thisted, Denmark – In service since 1984, demonstrating that well lifetimes can exceed 40 years.
- Reykjavik, Iceland – Deep wells supplying the capital’s heating system for decades, with periodic upgrades to pumps and casing.
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