by Gudmundur Ómar Fridleifsson, Wilfred Allan Elders, Greg Bignall

We propose to hold a science-engineering workshop in Iceland, September 2012, to review the lessons learned from the well IDDP-1 at Krafla, to plan the drilling and scientific study of the IDDP-2 at Reykjanes, and to broaden the scope of international participation. The Iceland Deep Drilling Project (IDDP) is a long term program by an industry-government consortium aimed at investigating very high-temperature, supercritical geothermal systems as a way of improving the economics of energy production. A feasibility study indicated that a well producing naturally occurring, high temperature and pressure, supercritical fluids would produce a power output an order of magnitude greater than that from a 300°C geothermal well. However reaching a supercritical geothermal reservoir requires drilling to depths of 4 to 5 km, with temperatures in the range of 450-600°C. In 2009 a well (IDDP-1) was drilled to test this concept at Krafla in NE Iceland, planned to reach 4.5 km depth. However, drilling had to be terminated at only 2.1 km depth when 900°C rhyolitic magma flowed into the borehole. The borehole was completed as a subcritical well producing from the contact zone of the intrusion. The well proved to be highly productive and is presently the world’s hottest production well. Since November 2011 it has been producing 12 kg/s of dry superheated, at wellhead temperatures of 439-443°C, pressures of 137 bars, and enthalpy of 3150 kJ/kg, and can produce up to 36 MWe. Numerous scientific studies of this well are being undertaken by an international team of scientists. Despite the interesting result of well IDDP-1, the IDDP has not lost sight of the original goal of producing steam from supercritical geothermal fluids. Planning is underway for drilling a second deep well in 2013-14, which will be on the Reykjanes Peninsula in SW Iceland, on the landward extension of the Mid-Atlantic Ridge. The hydrothermal fluid in the Reykjanes geothermal field is modified sea water, so this deep well will be the first opportunity worldwide to sample the root zone of a magma-hydrothermal system similar to those that are the sources of the black smokers on the world-encircling mid-ocean ridges. If the IDDP successfully demonstrates producing energy from very hot, magma-hydrothermal systems, this approach could be applied worldwide, wherever suitable young volcanic rocks occur. This has the advantage of increasing the power output of existing geothermal fields, and extending their resource base and lifetime, without increasing their environmental foot prints.

• An industrial-government consortium is planning to drill a 4.5-5 km deep geothermal well on the Reykjanes Peninsula in SW Iceland, the landward extension of the Mid-Atlantic Ridge. Its aim is to explore for supercritical, 450-600°C, geothermal resources and the consortium is open to participation by the scientific community. As the hydrothermal fluid in the Reykjanes geothermal field is modified sea water, this deep well will be the first opportunity worldwide for scientists to sample and directly study the root zone of a magma-hydrothermal system similar to the sources of the black smokers on the world-encircling mid-ocean ridges.
• To develop the scientific program that takes advantage of this opportunity a workshop is needed that (1) reviews past experience of drilling very hot wells,
• (2) develops the criteria for optimizing the drilling of the well,
• (3) reviews the specifics of the site selection at Reykjanes,
• (4) broadens the scope of international participation and disciplinary range of the science program,
• (5) coordinates strategies for funding both the engineering and science activities, and (6) produces a report to publicize the engineering, technical and scientific opportunities that this deep well will offer. The science program will study the physics and chemistry of the heating zone of a mid-ocean ridge by carrying out studies of water-rock interaction, petrophysical studies, and in situ stress field. Ideally fluid samples and spot drill cores will be obtained over a range of depths and downhole logging tools capable of operating at extreme temperatures will be deployed.

Geothermy, Iceland, Native Hydrogen, Natural Resources, Rifting, Supercritical Fluids, Thermal Regimes

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