Title: |
Cooling System for Borehole Tools |
Authors: |
Benedict HOLBEIN, Jörg ISELE, Luigi SPATAFORA |
Key Words: |
deep geothermal energy, borehole tools, |
Conference: |
Stanford Geothermal Workshop |
Year: |
2014 |
Session: |
General |
Language: |
English |
Paper Number: |
Holbein |
File Size: |
1237 KB |
View File: |
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The deep geothermal energy has a high potential for the future energy supply. It can be a renewable alternative as base load supplier for heat as well as electricity, but it is still far away from an economical and controllable technology. This is caused by 4 main problems which it faces today: The high drilling costs, the high investment risk, the insufficient predictability of risks and influenced by that the low public acceptance in many regions. The operations in boreholes are aggravated by high pressures, high temperature and corrosive thermal water. Particularly the high temperatures are a big difficulty because standard electronics get damaged when heated up over 70°C. High temperature electronic systems are still not available in an adequate range or very expensive. Since February 2012 a cooling system for borehole tools, serving solutions for the named problems, is being developed at the Institute of Applied Computer Science IAI (Karlsruhe Institute of Technology KIT), With it, it will be possible to investigate boreholes within their complete life cycle, starting with the drilling process and ending with permanent borehole logging during the plant operation. The system is a cooling unit especially designed for down-hole use. It fulfills a thermodynamic cycle process which allows a permanent cooling of tool components which are sensitive-to-heat, like electronic control and data acquisition units which are used i.e. in sensor systems. The cooling system is based on a modular and open design to make it usable with various investigation devices. This way it can be helpful for different problems in the geothermal energy sector. Used with a SPWD (Seismic Prediction While Drilling) tool at the final drilling phase, the aquifer could be located exactly and investment risks could be reduced significantly. With the cooling unit, sensor system for thermal water data could be used in the borehole without time limitations to transfer permanently real-time-data to the surface. This would give the opportunity of direct and contemporary engagement in case of risks or for an effective process control in plants. Since last year, when the development project was presented firstly at the 38th Geothermal Workshop in Stanford, further investigations of the technical aspects as well as project management issues have been worked on. The whole project has become more sophisticated and opportunities for the realization and application have been made available. To make the borehole cooling system ready for these tasks, we´re working on investigations of thermodynamic cycles and heat transfer processes, the engineering of custom built cooling-unit-components for the use under borehole conditions, different possibilities of connections like the integration in drill strings or wire lines, as well as techniques for the data transfer to the surface.
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