VAM® 21 has once again gone beyond standard applications to meet the requirements needed to extract hot fluid from geothermal wells. The premium connection was recently installed in two of Geo Dipa Energi’s geothermal wells in the Dieng Plateau in Indonesia withstanding temperatures of up to 330°C.
Exploiting the heat
Geothermal wells allow reaching underground resources to extract geothermal heat to the surface. The brine retrieved reaches elevated temperatures (in most extreme cases up to 400°C) which is used to feed turbines on power-station facilities that generate electricity. Geothermal energy is also suitable for direct-use applications such as district heating or cooling (low enthalpy geothermal). For both applications, ensuring well integrity and connection sealability are key.
Well integrity is a crucial aspect that must be maintained throughout the well’s lifecycle. The casing, especially, must be able to withstand all internal and external loads including invariable factors found in geothermal environments such as high-temperatures, high-strength rock, highly-fractured formations, corrosive fluid and wide range of pressures. The choice of a corresponding connection capable of withstanding such loads is therefore of equal importance.
VAM® 21 has been designed to sustain high levels of compression and to ensure sealability to both liquid and gas under combined loads at elevated temperatures. This is of utmost importance in geothermal applications since the extremely high temperatures of the fluid (250 to 400°C) induce high levels of compression on the production string and on its connections.
In addition to its qualification up to 240°C for critical oil and gas applications (such as HPHT wells) as per API 5C5:2017 CAL-IV, VAM® 21 has also been qualified up to 350°C under thermal cycles as per TWCCEP (Thermal Well Casing Connection Evaluation Protocol) for geothermal applications. VAM® 21 has a large product range capable of covering typical geothermal production casing sizes.
Geo Dipa Energi Case Study
Proving its high performance, VAM® 21 has been selected for geothermal projects around the globe, for instance for the city of Munich’s Geothermal Heating Plant in Germany, the Lake Assal Geothermal Project in Djibouti and for a deep geothermal project in the east of France.
More recently, Indonesia’s second biggest state-owned geothermal operator Geo Dipa Energi wished to install TWCCEP-qualified premium connections in one of their geothermal wells located in the Dieng geothermal area of the Dieng Plateau and chose VAM® 21 for the project.
Dieng wells produce water and vapor at temperatures ranging from 275°C up to 330°C, applying severe compression loads on production casing throughout its lifetime due to thermal cycles. For this project, it was therefore crucial that the premium connection selected complied with the TWCCEP protocol with an Application Severity Level (ASL) of a minimum of 290°C. VAM® 21 met Geo Dipa Energi’s requirements thanks to its resistance to high temperatures and to very high thermal-induced tension and compression cycles in cemented conditions. Thus, a production string of 13 3/8 68.00# and 72.00# L80 VAM® 21 was installed.
“We are very satisfied with the results obtained with VAM® 21 in our Dieng well”, says Yudi Hartono, Geo Dipa Energi Drilling Manager. “VAM® 21 was ran quickly and efficiently with zero rejects.” Additional tests were carried out in order to confirm well integrity. After the cementing job of the tie-back, a MFC (Multi Finger Caliper) and a CBL (Cement Bond Log) were ran to evaluate cement quality and VAM® 21’s resistance to the well’s temperature. Both tests presented great results, confirming VAM® 21’s reliability for geothermal wells. In total, VAM® 21 will be installed in 20 Geo Dipa wells.
Rising to the challenge
As the number of geothermal projects increase around the world, VAM® 21 is ready to face each customer’s specific challenges, providing the safest and most cost-effective solution possible.