The German Continental Deep Drilling Program (KTB)
GeoForschungs-Zentrum Potsdam
Dr. Rolf Emmermann
Chairperson：
Now I'd like to call upon Professor and Doctor Rolf Emmerman. He's going to talk about KTB and ICDP. Dr. Emmermann is the Scientific Executive Director of GeoForschungsZentrum Potsdam, and he's also the Professor of Giessen University. And he is responsible for the German Continental Deep Drilling project and he is currently the coordinator of the International Continental Drilling Program, ICDP.
Dr. Emmermann：
Thank you Mr. Chairman for your kind introduction and for the invitation.
(Fig.1)
The German Continental Deep Drilling Program, the KTB, was designed to study the properties and processes of the deeper continental crust by means of a super deep borehole targeted to reach the present day brittle-ductile transition in a normal continental crust. The program was carried out in distinct phases： the phase of concept definition, the phase of pre-site studies and site selection, followed by a pilot phase which consisted of drilling of a pilot borehole to 4 kilometers, and a one year logging and experimenting program in the pilot hole. The main borehole was started 1990 and completed after 4 years at a depth of 9,100 meters with a bottom hole temperature of about 270 degrees. In the final phase, which started in 1996, both boreholes are used as a deep crust laboratory.
(Fig.2,3,4,5)
The KTB which was completely financed by the German Ministry for Research and Technology - was carried out in close cooperation with the German industry. Actually this project can be regarded as a very fruitful symbiosis between fundamental geo-scientific research and technology development. This Figure shows the drill site when the pilot hole was drilled. We used a conventional drill rig leased from the industry. However, this rig was modified with a high-speed top-drive rotary system, and using thin-kerfed diamond core bits, a basement penetration of 4,000 meters, was achieved with a core recovery of almost 100%, so we had excellent material for the study of the rocks as a result of the pilot phase.
(Fig.6)
Well, the pilot phase had a number of important implications for the technical and also the scientific planning of the main borehole. One was that it was seen as absolutely mandatory to drill as vertically as possible in the main borehole in order to reach the envisaged depth. Therefore a self-steering automated vertical drilling system was developed, and continuously improved during the main phase and with this new technology, which could be used to 7,500 meters, the borehole was absolutely vertical. The deviation at 7 km depth is less than 10 meters.
(Fig.7)
The next Figure shows the casing scheme of the main borehole.
(Fig.8,9) The most important technical decision was not to convert a heavy drill rig from the industry, but rather to build a new one. However, by using proven existing components, this is the result - within one year a new drill rig could be designed and constructed which is the biggest land-based drill rig. It has a height of 84 meters; it is electrically driven; fully automatic and can be handled by 3 people. It has a number of new developments including an automatic pipe handling system.
