The Iceland Deep Drilling Project (IDDP): An investigation of the supercritical geothermal regime

An international industrial consortium has initiated a program in Iceland of deep drilling into very high-temperature geothermal resources. The aim is to investigate the technology and economics of producing energy from geothermal systems at supercritical conditions. The IDDP will drill a series of wells to depths of 4 to 5 km in order to reach temperatures of 400–600°C. Today, geothermal wells in Iceland typically are about 2.5 km in depth and produce steam and water at about 300°C, or less, enough to generate about 4-7 megawatts of electricity. It is estimated that producing steam from a well reaching temperatures >450°C, and at a rate of 0.67 cubic meters a second, could generate 40-50 MWe. If this test of the concept is successful, it could lead to major improvements in the development of high-temperature geothermal resources worldwide.
The consortium funding this deep drilling project consists of three leading Icelandic power companies, Hitaveita Sudurnesja Ltd., Landsvirkjun, Orkuveita Reykjavikur, together with Orkustofnun (the National Energy Authority) and Alcoa Inc. (an international aluminum company). The three power companies financed a pre-feasibility study for the project that was completed in 2003. Each of the three power companies is committed to drill, at their own cost, a 3.5-4.0 km deep well in a geothermal field that they operate. The design of these wells will permit them to be deepened to 4.5-5.0 km by the IDDP, funded by the consortium. In addition, the International Continental Scientific Drilling Program (ICDP) and the US National Science Foundation (NSF) is funding the acquisition of rock and fluid samples for scientific studies.
The first deep IDDP well will be drilled in the latter part of 2008 in the Krafla geothermal field near the northern end of the central rift zone of Iceland, within a volcanic caldera that has had recent volcanic activity. Two new wells, about 4 km deep, will then be drilled at the Hengill and the Reykjanes geothermal fields during 2009-2010, and subsequently deepened. In contrast to the fresh water systems at Krafla and Hengill, the Reykjanes geothermal system produces hydrothermally modified seawater on the Reykjanes peninsula, in southern Iceland, where the Mid-Atlantic Ridge comes on land in southern Iceland. Processes at depth at Reykjanes should be similar to those responsible for black smokers on ocean spreading centers.
The IDDP has engendered considerable international industrial and scientific interest. In preparation for investigating the data and samples that will be recovered by deep drilling, research is underway on samples from existing wells in the target geothermal fields, and on exposed "fossil" geothermal systems that have conditions believed to be similar to those that will be encountered in deep drilling by the IDDP. The details of Krafla’s geology, and the drilling and fluid handing strategy, are described in accompanying papers at this conference.