| Abstract |
The Iceland Deep Drilling Project (IDDP) is being carried out by an international industry-government consortium in Iceland, in order to investigate the economic feasibility of producing electricity from supercritical geothermal reservoirs. Producing high enthalpy supercritical fluids at high rates of mass flow requires drilling to depths of 4 to 5 km and reaching temperatures of 450–600°C. While drilling such deep wells is more expensive than conventional geothermal wells drilled to 2 to 3 km depth, modeling suggests that producing superheated steam from a supercritical reservoir could potentially increase power output of geothermal wells by an order of magnitude. To test this concept the consortium plans to drill a deep well in each of three different geothermal fields in Iceland. Drilling the first deep IDDP well is currently underway within the central active rift zone of NE Iceland at Krafla, which lies in a volcanic caldera. A large magma chamber at 3-7 km depth at the center of the caldera is believed to be the heat source of a geothermal system currently supplying steam to a 60 MWe power plant. The plan is to case the IDDP-1 to 3.5km depth and then deepen it to 4.5 km. Several spot cores for scientific studies will be collected between 2400 m and the total depth, which should be reached in early August 2009. After the well heats, it will be flow tested and, if successful, a pilot plant for power production should follow in 2010. The purpose of presenting this paper is to report the initial results from this drilling. Two new wells, 3-4 km deep, will then be drilled during 2010- 2011 in SW Iceland at the Hengill and the Reykjanes geothermal fields, and subsequently deepened into the supercritical zone. In contrast to the fresh water systems at Krafla and Hengill, the Reykjanes geothermal system produces hydrothermally modified seawater on the Reykjanes peninsula, where the Mid-Atlantic Ridge comes on land. The IDDP has engendered considerable international technical and scientific interest, and a large team of international scientists is involved. If these tests of the supercritical regime prove successful, they could lead to major improvements in the economics of high-temperature geothermal resources worldwide. In situations where production is limited by low permeability, supercritical fluids could be particularly attractive targets for engineered geothermal systems. |