Downhole pressure and temperature measurement tool: design, prototyping, and validation for geothermal applications

Date

2025-3-6

Author

HIDIROĞLU, İNANÇ ALPTU

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Geothermal energy is a crucial renewable energy source due to its sustainability and environmental benefits. Accurate pressure and temperature measurements in geothermal reservoirs are essential for optimizing energy production, monitoring fluid dynamics, and ensuring long-term system efficiency. While advanced downhole measurement tools are commercially available, Türkiye has not yet developed its system for reservoir monitoring. This study investigates the feasibility of developing a domestically produced downhole measurement tool and evaluates its performance under operational conditions to establish its reliability and accuracy in geothermal reservoirs. The research follows a structured methodology, beginning with an extensive literature review to define key design parameters. The tool was modeled using SolidWorks for 3D mechanical design, and its thermal and structural behavior was analyzed using COMSOL Multiphysics. Simulations were performed to evaluate heat insulation, mechanical integrity, and material performance under high-temperature conditions. After manufacturing, experimental validation was conducted through laboratory tests, comparing real-world performance with computational predictions. The final prototype successfully operated at 145°C and 3000 psi, achieving a measurement accuracy of ±0.1°C and ±0.1 bar. Simulation results and experimental data verified the tool's reliability for geothermal applications in low and medium enthalpy reservoirs. Additionally, material selection was optimized, and stainless steel, Teflon, and PEEK were evaluated for their high-temperature resistance. The comparison between the experimental data and COMSOL simulation results revealed strong agreement, validating the thermal model’s accuracy. The tool’s internal temperature response exhibited a characteristic thermal lag, effectively captured by the simulation, which confirmed the success of the insulation design. The tool was also simulated under wellbore descent conditions and demonstrated the capability to maintain thermal stability and measurement accuracy at depths up to 1100 meters in 200°C geothermal environments. This study presents a pioneering step in Türkiye’s domestic geothermal technology development by providing a cost-effective and customizable solution for reservoir monitoring; it represents a foundational step in Türkiye’s domestic development of geothermal measurement tools by integrating CAD modeling, computational simulations, and experimental validation into a unified framework. The modular electronic board designed for this tool includes additional capabilities, such as solenoid valve control, which can facilitate the development of a more advanced tool for pressure-temperature measurement and fluid sampling. Furthermore, while initially designed for geothermal applications, the tool’s dimensions and pressure resistance allow for potential applications in petroleum and natural gas wells.

Subject Keywords

Geothermal energy, Geothermal reservoirs, Pressure and temperature measurement, Downhole logging tool, COMSOL simulation, Experimental validation, Thermal management

URI

https://hdl.handle.net/11511/114106

Collections

Graduate School of Natural and Applied Sciences, Thesis