Iceland Deep Drilling Project (IDDP): Drilling Targets for Supercritical Fluid

Abstract

This paper on the IDDP is one in a series of five in this conference volume. The primary objective of the IDDP is to find supercritical hydrous fluid at drillable depths, at 450-600?C, and to study its potential energy and chemical compositions. This is to be accomplished by drilling to depths of 5 km or less. Cemented casings to 3.5-4 km depth are necessary to case off the upper part of the hydrothermal system at subcritical condition. In this paper we discuss the background for the drill site selection in the Krafla, Nesjavellir and Reykjanes high-temperature geothermal fields. During 2001-2002, available data on surface and subsurface geology, geophysics, geochemistry and environmental aspects of the three fields of concern has been evaluated in a feasibility study. Four to six potential drill sites have been considered in each of the high temperature fields. The priority order for the recommended drill site for the first IDDP well is Nesjavellir, Krafla, Reykjanes. The reason for this priority order is mostly the desire to encounter supercritical fluid at as shallow a depth as possible, and to obain supercritical fluid as dilute as possible. The same order also has technical and cost benefits, while the international science community may just as well like to see the wells drilled in the reverse order. A decision on whether to drill the first well remains to be made.