| Abstract |
At the International Geothermal Centre (GZB) in Bochum R&D work has been under way during the past years to investigate and optimize drilling technologies for geothermal applications. Amongst others drilling with Coiled Tubing has been investigated and followed up on in numerous projects worldwide together with industry partners. Today, especially horizontal drilling of laterals to improve or gain access to geothermal reservoirs is a number one topic. Geothermal stimulation in more or less competent rock has to be realized without the detrimental side effects of “fraccing” , which are going through the general public right now.Therefore, horizontal drilling technologies as a potential substitute or solution for stimulation gain new and greater momentum, especially for the geothermal industry. This drilling of laterals to connect 2 vertical boreholes or simply produce large surface areas in a reservoir may very efficiently be done with the use of Coiled Tubing drilling technologies. This drilling method, which uses a continuous drill string from a spool / coil, rather a set of jointed pipes screwed together, has already been partly proven in the oil & gas field during the past 30 + years.However, newest developments in engineered materials, BHA assemblies, directional drilling, DTH hammers, may be Laser and other drilling technologies, do call for a more adapted, better, and broader use of this technology. That´s why GZB in Bochum has been designing, setting up and currently bringing into service a first CT drilling demonstrator rig for limited depth applications. This unit, intended for scientific work, testing and real drilling, especially with the use of composite coils, will help to improve horizontal drilling for the application in geothermal reservoirs. Furthermore, new drilling technologies like DTH hammers, potentially Laser or other thermal drilling applications, directional tools etc. will be tested and developed on the CT drilling demonstrator in Bochum. A brief introduction of coiled tubing drilling, the set up and possibilities and first results of the CT demonstrator will be presented. |