| Abstract |
Dr.Jörg Isele, Chris Bauer, Stefan Dietze, Benedict Holbein, Luigi Spatafora The ZWERG Project: a Platform for Innovative Logging Tools Analysing the needs of logging tools leads to the discovery that a lot of equipment, concepts and engineering details are similar, no matter of the probes respective service function. The logging truck, the control cabinet, the winch, the wireline cable and the cablehead follow a couple of quasi standards. The tools vary in size, but they all need to dock on the cablehead. They have to be housed in a corrosion resistant and pressure tight shell. Only few tools work without electronics. Those using electronics must ensure enough lifetime for the sensible devices since temperature resistant electronic equipment is very rare. One support is keeping the heat of the reservoir outside by insulation with Dewar flasks. Another one is the provision of a heat sink either for a limited time span with phase change materials or without a time limit by using an active cooling system, based i.e. on the principle of the compression refrigeration machine. The power supplies for the electronics and solutions with sufficient bandwidth for an intensive online communication are only two of many more examples for further features, needed for almost every tool. ZWERG is the German translation of dwarf, the small miners in many tales. The idea of the ZWERG project, running since the year 2010, is to provide a common platform for all kinds of logging jobs. Like a dwarf, ZWERG can bring different tools into the borehole and use them. Of course the machine will need the adoption of specialized equipment, which always is an engineering task. ZWERG is an open source project at its start. Many basics have been developed and evaluated, which will be published on the ZWERG website. The information given is multi layered, as the housing example shows: On the website the equations and rules for the dimensions are listed. Further an estimation for the material is made which goes beyond the suggestion of Inconel alloy 718, which is widely used in the industry. It is also mentioned where that material may be bought in the correct dimensions for a 200°C and 60 MPa environment, which is found in 5km deep wells in Central Europe. In addition an indication of the costs is given. Finally you can find blue prints of construction details like the interface to adjacent devices. The usefulness of the ZWERG platform has been evaluated on the GeoKam project. GeoKam is an online video tool for deep geothermal wells and it is far more than just a mechanical device. Important components are the fast data transmission through a standard wireline cable using software defined radio techniques and the picture compression with the ZWERG HiTES controller (high temperature embedded system). Field tests with GeoKam will take place in 2015 in a borehole near Munich. The toolkit for the ZWERG platform will be enlarged by other devices and new dimensions in diameter etc. A new project called COBOLD (a relative of the dwarfs) will add the important cooling-system without time limit to the tool-kit. In another yet unnamed project, the aim will be to design a water sampling probe able to preserve pressure and temperature of the geothermal water sample until it gets to the lab. The open platform ZWERG is ready for use. If multiple designers use it and publish their experience on the ZWERG website, it will become less difficult to develop a new probe. More affordable borehole probes will enlarge the knowledge that is so important for geothermal industry: What do we find down under our feet and how can work be done in that hardly accessible and rough environment? |