THERMOCASE® VIT
Optimizing geothermal heat efficiency
Geothermal closed-loop systems provide the operator with the ability to harness heat from virtually any location on the globe. These systems offer flexibility in selecting the fluid used, which can be water or other options like supercritical CO2 which help optimize the heat extraction and consequently enhance power output. These systems usually need a single well and can be based on a “pipe-in-pipe” solution, with Vallourec THERMOCASE® vacuum-insulated tubing (VIT) as the key component.
• Once it has been heated up, the fluid travels up the THERMOCASE® VIT and exits at the surface, where it is used to power turbines or directly for district heating.• THERMOCASE® VIT’s best-in-class insulation and high-service temperature, make it a central component of the downhole heat exchanger.
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• To maximize efficiency, the cool fluid is injected in the annulus between the THERMOCASE® VIT and the casing pipe and gets heated up while flowing down the well. • Once it has been heated up, the fluid travels up the THERMOCASE® VIT and exits at the surface, where it is used to power turbines or directly for district heating. • THERMOCASE® VIT’s best-in-class insulation and high-service temperature, make it a central component of the downhole heat exchanger. |
Case Study
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INCREASED POWER GENERATION WITH THERMOCASE® VITWhile closed-loop systems offer advantages including reduced costs and greater heat extraction, they require special tubing. A geothermal operator planned to use an existing unproductive geothermal well in California, USA, for closed-loop testing. The initial casing size was 9-5/8” with an open hole depth of 2,500 meters and a downhole temperature of 160°C. After consulting Vallourec, an optimized design was created using 4.5” x 3.5” THERMOCASE® VIT for a total depth of 1,500m. Vallourec adapted the VIT design to include centralizing fins and clamps, allowing fiber optic cabling to be run downhole for instrumentation. Thanks to the THERMOCASE® VIT system, generated power is expected to increase from 0.6MW to 4MW electric. |
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