Title:

The Science Program of the Iceland Deep Drilling Project (IDDP): a Study of Supercritical Geothermal Resources.

Authors:

Wilfred A. Elders, and Guğmundur Ó Friğleifsson

Key Words:

Supercritical fluids, enhanced geothermal resources, magma energy, deep drilling, Iceland.

Geo Location:

Krafla, Iceland

Conference:

World Geothermal Congress

Year:

2010

Session:

39. Iceland Deep Drilling Project

Language:

English

Paper Number:

3903

File Size:

1843KB

View File:

Abstract:

The main goal of this development and research program in Iceland is to investigate interaction of high-temperature, supercritical (400-600 oC) hydrothermal fluids with basaltic crust in Iceland, where the Mid-Atlantic Ridge emerges from the ocean. The Iceland Deep Drilling Project (IDDP) is a long-term collaboration between a consortium of Icelandic power companies and the Icelandic government, together with two international partners, formed to investigate the economics of deeper, hotter, geothermal resources. The consortium agreed that the operators on the Reykjanes, Hellisheidi, and Krafla geothermal fields would each fund the drilling of a well 3 to 4 km deep and that the IDDP would fund the deepening these wells to >4 km deep, to reach temperatures >450oC with the basic aim of exploring supercritical hydrothermal fluids as a possible energy source. Supercritical fluids have high enthalpy and greatly enhanced rates of mass transfer and chemical reaction.
Drilling the first deep well commenced in 2008 in the Krafla geothermal field within a volcanic caldera in the central active rift zone of NE Iceland. Volcanic eruptions and rifting last occurred there in 1974-85. The IDDP-1 well was drilled and cased to 800 m depth in November 2008 before the winter snows. Drilling resumed in the spring of 2009 and in mid-April had reached 2 km This was followed by more than two months of problems, hole caving, getting stuck, twist offs, cement jobs, side tracks and a failed spot coring attempt. The reason for this caving leading to drilling problems became clear on June 24th at 2104 m depth when rhyolitic magma, with an estimated temperature of 1050 oC, flowed into the drill hole. It was decided not to continue drilling and the well was completed with a cemented production casing and a hanging slotted liner set a few meters above the quenched magma. At the time of writing, a tracer test is underway to check connectivity with wells neighboring wells and surface valves have been installed in preparation for a flow test to evaluate the fluid chemistry, steam production, and potential-power output.
Depending on the result of this flow test of well IDDP-1, future possibilities might include the creation of the worlds hottest Enhanced Geothermal System (EGS), for example by injecting water into an adjacent well and producing superheated steam from the magma. An advantage of such a strategy would be that any acidic magmatic gases might be neutralized by injecting suitably treated water.

Two new wells, ~4 km deep, will then be drilled at the Hengill and the Reykjanes geothermal fields during 2011-2012, 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, in southern Iceland. This presents an ideal situation to study high-temperature magma-hydrothermal systems analogous to those responsible for the black smokers at submarine divergent plate margins, but at greater depth and temperature than has been possible so far by the ocean drilling program.
The IDDP has engendered considerable international scientific interest and its initial results will be reported in a number of papers at the World Geothermal Congress. The US National Science Foundation and the International Continental Scientific Drilling Program are jointly funding obtaining cores and samples for scientific studies


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