Skip to main content

Unlocking the potential of geothermal energy

Published by , Editor
Energy Global,


In recent years, the global energy industry has experienced a notable surge in geothermal energy projects as the shift towards more sustainable energy sources intensifies.

Geothermal energy is a form of renewable energy derived from the heat stored beneath the Earth's surface, originating from the decay of radioactive isotopes and residual heat from its formation billions of years ago. The heat continuously flows outward towards the surface, where it can be harnessed for various purposes.

The energy source can be used for electricity generation, with geothermal power plants utilising steam or hot water from underground reservoirs to drive turbines, generating electricity. Hot water from geothermal fields can also be used directly for the purpose of heating buildings and industrial processes while geothermal heat pumps, which utilise the relatively stable temperature of the ground, can provide heating, cooling, and hot water for residential and commercial buildings.

A particularly unique benefit of the geothermal energy is the abundance and reliability it provides. Unlike solar or wind power, this renewable energy provides a consistent source of electricity, unaffected by weather conditions or time of day. This positions it as a crucial player in the transition away from fossil fuels, offering a stable and resilient alternative.

The rise in geothermal projects, particularly in Europe and the US, also brings significant potential for economic growth and job creation. Investment in these projects not only fosters technological innovation, but also stimulates local economies, creating employment opportunities and driving sustainable development.

In a recent Wood Mackenzie report, under a net-zero 2050 scenario, it forecasts the potential for more than 20 000 producing wells, requiring an annual investment of around US$60 billion by 2050. The growth in the sector is evident with key projects sanctioned across Europe and North America in particular, where government funding and research grants support the development of new exploration. For example, 2023 saw the UK’s first new deep geothermal project in 37 years come online in Cornwall, England. In the US, Fervo Energy started drilling on its geothermal energy project, Cape Station, in Utah with the work set to deliver 400 MW of continuous carbon-free electricity by 2026.

Evaluating industry challenges

However, amidst its rapid rise, the sector presents a myriad of challenges which are shaping the trajectory of the industry. Currently, one of the main barriers for growth is the cost. Geothermal projects often require substantial upfront investments for exploration, drilling, and infrastructure development which can often be too expensive for investors and developers, especially when compared to more established energy sources. To compete with other flexible low-carbon power generation technologies, CAPEX costs would need to fall by 30 – 60%.

There are also a number of geological uncertainties with geothermal energy, primarily in the exploration and development stages. Identifying, and accurately characterising suitable reservoirs requires extensive geological assessments, which do not always guarantee successful outcomes. Uncertainties regarding reservoir size, temperature, and permeability vary from site to site and are difficult to predict with precision. This can lead to increased project risk, ultimately deterring investment.

Once a geothermal reservoir is accessed, managing its production and re-injection processes becomes crucial to sustain energy extraction and maximise resource recovery. Reservoir engineering techniques are employed to optimise well performance, monitor reservoir behaviour, and prevent issues such as reservoir cooling, mineral scaling, and fluid depletion. Implementing effective reservoir management strategies requires continuous monitoring, data analysis, and adaptive decision-making to maintain reservoir sustainability and longevity.

Geothermal wells are drilled deep into the Earth's crust to access hot reservoirs, with depths ranging from a few hundred metres to several kilometres. Accessing geothermal reservoirs often requires drilling directional wells that can deviate from vertical to reach specific targets which can add complexity to well planning, casing design, and drilling fluid management.

Drilling under such high temperatures and pressures, corrosive fluids, and challenging geological conditions requires specialised equipment and expertise. Wellbore stability, directional drilling, casing design, and cementing operations are critical aspects of geothermal drilling that demand advanced engineering solutions and meticulous planning to mitigate risks and ensure successful well construction.

This presents a unique opportunity to the oil and gas sector, with transferrable skills and technologies available to support the growing sector. Particularly with regards to drilling expertise, the traditional energy market is adept to operating in challenging environments and techniques such as directional drilling and wellbore management which are directly applicable to geothermal exploration and development. The knowledge of reservoir engineering and management gained from the oil and gas sector can also be leveraged to optimise geothermal reservoir performance and maximise energy extraction.

Advanced technologies traditionally adopted in oil and gas wells are also playing an increasingly pivotal role in supporting geothermal projects. Coretrax, a global leader in oil and gas well integrity and production optimisation, has a growing footprint in the geothermal sector, deploying its technology to support projects across the globe.

Driving efficiencies through effective wellbore clean up

During a geothermal drilling campaign in Denmark, an operator required an effective and efficient wellbore clean up solution for multiple casing envelopes.

Working in partnership with a local agent in Germany, Coretrax selected four wellbore cleanup tools – the Hi Pro Non-Rotating Casing Scraper, Hi Pro Casing Brush, SP Magnet and CX-Junk Filter Sub – to be deployed in tandem as a one-trip solution. To deliver greater efficiencies, the technologies were prepared into sub-assemblies at the agent’s site in Germany prior to shipping to ensure reduced rig time while limiting extra handling exposure at the site. The systems were prepared for three casing envelopes – 7 in., 9 5/8 in. and 13 3/8 in. To provide further efficiencies, prior to deployment, Coretrax delivered training to the operator’s personnel which enabled reduced personnel on site, with 24/7 support provided from the company’s base in Aberdeen, the UK.

https://d11onib03523a2.cloudfront.net/media/Figure+1.jpg
Four wellbore clean up tools were selected to deliver a one-trip solution.

The Hi-Pro Casing Scraper has six blades specially aligned on the body to provide maximum contact with the casing inner diameter (ID) while running-in and reciprocating the string while the Hi Pro Casing Brush has two specially designed brush sleeves. The body provides absolute safety and security by locking each brush segment onto an integral part of the brush. Both systems provided full 360° coverage for the operator, with the non-rotating brushes and blades and self-centralising stabilisers ensuring no additional wear or damage to the casing while rotating the string.

https://d11onib03523a2.cloudfront.net/media/Figure+2.jpg
The Hi Pro Casing Brush has two specially designed brush sleeves to deliver full coverage.

The SP Magnet has a minimum of 10 high-strength magnet strips to maximise the surface catchment area and continually captures ferrous materials from the moment it passes the rotary table until it is recovered back to surface. With a large carrying capacity, the system’s high strength magnets are temperature resistant so could withstand the high temperatures of the well. For additional assurances, the CX-Junk Filter Sub allowed the removal of non-metallic debris – as the circulation slows, the denser materials drop over the lip and into the filter cup.

During the project, challenging hole conditions meant the 7 in. liner was unable to reach the designated depth but, following a run with the wellbore clean up assembly for the 13 3/8 in. x 9 5/8 in. section the operator subsequently ran the 7 in. liner successfully before a second wellbore clean up trip was performed in the 7 in., 9 5/8 in. and 13 3/8 in. and the well was successfully displaced from water-based mud to water. The combination of Coretrax’s technology and effective pre-planning delivered significant rig time savings for the operator, with additional wells within the field now underway.

Enhanced safety with advanced circulation

Geothermal wells operate under high temperatures, making it crucial to maintain circulation of drilling fluids to cool the drill bit and carry cuttings to the surface during the drilling phase. Circulation tools help to ensure a consistent flow of drilling fluid throughout the drilling process, preventing the well from becoming blocked or compromised. Circulation technology also supports with temperature control, ensuring that overheating is prevented while supporting proper circulation to prevent formation damage.

https://d11onib03523a2.cloudfront.net/media/Figure+3.jpg
Geothermal wells operate under high temperatures, making it crucial to maintain circulation of drilling fluids.

Coretrax recently supported a geothermal campaign in New Mexico when a US operator was planning to drill a closed-loop geothermal land well which had bottom hole temperatures estimated at 400°C. The extreme heat had potential to cause equipment failure so a reliable method to ‘stage’ in the hole to cool down the temperature sensitive measurement while drilling (MWD) technology and other directional tools was required.

Staging is a common practice for high temperature wellbores to prevent MWD failures which normally involves pumping conventionally though the bit. However, this traditional approach would have resulted in the motor rotating the bit and causing possible damage in the cased and upper granite section. During the drilling of the granite section, multiple bit runs were required to reach tagging depth.

https://d11onib03523a2.cloudfront.net/media/Figure+4.jpg
DAV MX downhole circulation bypass tool uses smart darts to provide fast circulating options.

The company’s DAV MX downhole circulation bypass tool uses smart darts to provide fast circulating options, and has activated at depths greater than 31 000 ft, so was chosen as the most effective system for the project. The system was placed within the drill string to provide assurances and could be activated if required, providing versatility and contingency to the operator. The technology was deployed with a split flow dart (SFD) which splits the flow, directing a small percentage to the bottom hole assembly (BHA) below the tool and diverting a large portion of the flow out through the open circulating sub which provides effective cooling to the BHA and borehole, whilst allowing a higher flow rate in casing.

The SFD enables a limited flow through the motor and bit so as not to have it rotating at high RPMs whist simultaneously achieving a high flow rate downhole to sufficiently cool the BHA and borehole. This results in significant time savings during application, less casing wear, a functioning MWD and no damage to the drill bits. The application of the DAV MX effectively reduces bottom hole temperature and reduces circulating time while maintaining the integrity of casing and drill bits.

Accelerating a net-zero future

The rise of geothermal energy projects marks a pivotal moment in the global energy transition. While it presents immense opportunities for clean and reliable power generation, addressing the associated challenges will require concerted efforts from governments, industry stakeholders, and the scientific community. By navigating these challenges effectively, the industry can unlock the full potential of geothermal energy and accelerate the transition towards a sustainable future.

 

 

For more news and technical articles from the global renewable industry, read the latest issue of Energy Global magazine.

Energy Global's Autumn 2024 issue

Dive into the latest renewable energy insights in the Autumn issue of Energy Global, out now! The issue starts with an insightful guest comment from Cristiano Spillati, Managing Director at Limes Renewable Energy where he discusses the need for European renewable energy suppliers to accelerate the rate of the energy transition. This is followed by a regional report from Cornwall Insights on the battery energy storage industry in Australia. This issue explores key topics including offshore wind subsea cables, offshore wind support vessels, digitalisation, wind turbine components, and more!

Read the article online at: https://www.energyglobal.com/special-reports/31102024/unlocking-the-potential-of-geothermal-energy/

You might also like

 
 

Embed article link: (copy the HTML code below):