| Abstract |
At the Karlsruhe Institute of Technology an inspection system is being developed for geothermal boreholes. The aim is to transfer live pictures from a 4000 m borehole via a wireline to the earth’s surface. At this depth, temperatures of up to 165°C and pressures up to 60 MPa can be expected, so that the mechanics and the electronics are under severe load conditions. In addition, the corrosive thermal water, possible shocks in operation, the friction between the borehole probe and the borehole wall and sometimes poor visibility have to be taken into account. Since February 2013 [1] investigations from the GeoKam project have been carried out in the area of the mechanical components and first solutions could be developed. The work can be divided into two areas: a) the housing, which is exposed to the pressure, temperature, the corrosive thermal water, the shock and friction and b) the core, which is protected by the housing and only exposed to high temperatures. The extreme environmental conditions, which act on the body, only allow a limited choice of metallic materials. Due to the necessity of a camera, also transparent ceramics are required in addition to metals. The combination between metal and ceramic demands a suitable jointing technology, which seals the housing and can withstand high pressure. Because of the high temperatures in the core affecting the camera, the camera electronics, the transmitting electronics and the power supply, these components must be protected by the use of a cooling and insulation. The insulation has to be transparent in the area of the camera. Since the beginning of the investigations some solutions for the problems mentioned above have already been developed and some prototypes for first attempts will manufactured in 2014. This paper reports on the status of development. [1] Activities earlier than that have been reported last year: Isele J., Holbein B., PROCEEDINGS, Thirty Eighth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 11-13.2013, SGP-TR-198 |