Tenaris: the leading edge of geothermal well casing design

With over 30 years of experience in the business worldwide, the company has recently been selected to supply casing for two strategic geothermal projects in Europe.

Casing design solutions

Within the wide range of products that the company offers for industrial solutions, Tenaris manufactures and supplies pipes for geothermal applications, which use water or steam at around 250°C. In recent years, there has been increasing interest in medium-enthalpy projects, characterized by temperatures between 70 and 120°C (158 to 248 °F) and generally used for district and industrial heating.

In this context, the company has over 30 years of experience in the geothermal business worldwide, in countries such as Italy, Iceland, Indonesia, Japan, and others, providing customers with specific products, proprietary steel grades, and comprehensive support from well design up to on-site installation.

"Relevant thermo-mechanical loads and cycles characterize geothermal wells. The compression resistance of the connection used for well casing becomes a critical parameter to withstand thermal expansion and cycling. Casing sizes depend on the fluids that they produce. In the case of wells producing steams, typically, the completion is tubbiness to maximize the passage area of the well. While in the ones producing water, we use a shallow tubing connected to an Electric Submersible Pump (ESP)," said Raffaello Zambetti, Tenaris Well Design Solutions Manager.

Two leading projects

Recently, Tenaris has been selected to supply casing for two geothermal projects in Europe. These projects leverage the constant renewable source of energy to reduce the dependence on fossil fuels.

Northwest Romania has been pursuing a transition towards renewable sources. Several wells have been completed to increase the energy extracted from deep geological formations. The company has been awarded the complete tubular supply of the most recent well, expected to be drilled in the first half of 2021. For this project, Tenaris will supply the TenarisHydril Wedge 511® connection, an integral true-flush technology that achieves higher production rates while still granting the clearance needed for a smooth installation. 

"The TenarisHydril ER is a high-performance coupled connection most frequently used for geothermal applications. It has been used for over 20 years in geothermal projects with zero failures reported in more than 500 wells, providing both easy stabbing and fast make-up, while maintaining 100% compression and tension efficiency," clarified Paolo Novelli, Tenaris Technical Sales Senior Manager.

On the other hand, Tenaris also investigated the most cost-effective solution for the geothermal well, which exhibited acids and other corrosive agents, for a spa project in Western Europe. For the 9 5/8" production string, the selected answer was casing with internal coating, which provides exceptional resistance to corrosion. The TenarisHydril Wedge 563® connection was chosen thanks to its Recess Free Bore (RFB) configuration that allows a Corrosion Barrier (CB) ring to ensure the coating continuity connection area.

"We have been supplying casing to geothermal operators for more than 30 years, and we want to continue supporting them with newly developed, tailored solutions for geothermal applications to maximize the safety and efficiency of their operations," pointed Paolo Novelli.

Dopeless® technology: a solution to extreme conditions

Geothermal energy can be one of the most reliable, sustainable, and affordable types of renewable energy. Drilling operations entail several challenges for OCTG and connections, presenting high bottom-hole temperatures (exceeding 300°C), thermal cycles challenging compression resistance, and high well-head steam pressure in complex corrosive environments. 

As a solution, Tenaris provides connections with high compression resistance and corrosion-resistant steel grades with high yield strength. 

With its Dopeless® technology, connections are supplied RunReady™, and there is no need to use running or storage compounds, simplifying handling and yard operations. 

TenarisHydril Wedge and Blue® connections offer an extensive range of product solutions to meet the needs of drilling and completion operations across all applications. Dopeless® technology is an industrially applied coating that simplifies pipe handling and running while minimizing environmental footprint. 

Dopeless® production lines are located in the United States, Mexico, Argentina, the UK, Italy, Kazakhstan, Romania, and Indonesia. Additionally, 11 self-contained units have been deployed worldwide, capable of supporting the application of the technology wherever needed.

Benefits of the Dopeless® technology

  • Reduced running time up to 25 %.
  • Zero discharge and reduced risk.
  • Offshore 10 % savings on total pipe cost.
  • Reduce the risk of make-up problems, increasing the reliability of the running.

From the center of the Earth

According to the International Renewable Energy Agency (IREA), Geothermal is a type of renewable energy taken from the Earth's core. It comes from the heat generated during the original formation of the planet and the radioactive decay of materials. This thermal energy is stored in rocks and fluids in the center of the globe. Water or steam carries the geothermal energy to the Earth's surface. 

Depending on its characteristics, it can be used for heating and cooling purposes or be harnessed to generate clean electricity. However, high or medium temperature resources are needed for electricity, usually located close to tectonically active regions.

The slow decay of radioactive particles in the Earth's core is a process that happens in all layers and which produces geothermal energy.

The four primary layers of the Earth from where geothermal energy comes are:

  • An inner core of solid iron that is about 1,500 miles in diameter.
  • An outer core of hot molten rock called magma that is about 1,500 miles thick.
  • A mantle of magma and rock surrounding the outer core that is about 1,800 miles thick.
  • A crust of solid rock forms the continents and ocean floors 15 to 35 miles thick under the continents and 3 to 5 miles thick under the oceans.

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