WorldWide Drilling Resource

19 WorldWide Drilling Resource ® FEBRUARY 2018 Record Depth Achieved in Finland Adapted from Information by Numa Numa played an integral role in the success of drilling Finland’s deepest hole in Otaniemi, Espoo, Finland, by drilling to 15,092 feet for the country’s latest geothermal venture. The project required drilling two boreholes for a new geothermal plant; the first hole would be used for pumping water through the bedrock belowground which wi l l act l ike an underground heat exchange. The heated water will then be forced back up the second borehole to a heat plant system on the surface. The plant is expected to produce up to 40 megawatts of geothermal heat, which is up to 10% of the district’s heating demand. The geothermal project used multistage, telescopic drilling to reach its goal. The first stage maximized Numa’s Patriot 185 hammer and 26-inch retained bits with PCD carbide to drill to 900 feet. The second stage used a 17.638-inch PCD bit to drill to 9600 feet where the hole was cemented. To make a sure strict hole diameter was maintained throughout the drilling process, the third stage used a Numa Patriot 125 hammer specially fitted with fully-retained PCD drill bits ranging from 12-12.5 inches until the final depth of 15,092 feet was achieved. Overall, Numa’s down-the-hole (DTH) products delivered an average penetration rate of 33-82 feet per hour, drilling up to 980 feet per day in the hardest rock formations in the country. The company’s products achieved the record-breaking depth in only a few short months, 70% less time than other deep hole drilling methods. As with many deep hole drilling projects, keeping a consistent hole diameter and verticality were critically important. The project required Numa to design and manufacture many customized drilling components including custom porting and adapters to facilitate proper air lift. Special stabilizers were also provided by Numa to support verticality of the drilling process. Numa President Ralph Leonard said, “Successful deep hole drilling has been the forte of Numa products for many, many years. Whether it is drilling to 17,600 feet in West Texas, or 15,092 in Finland, Numa has the DTH technology, expertise, and service to get the job done right.”