Experience of Exploiting Icelandic Geothermal Reservoirs

Abstract

Geothermal reservoir engineering studies have been pursued for years in Iceland, concurrently with the utilization of the various geothermal fields. This ha been essential in order to understand the responses of the reservoirs to exploitation, and to sustain and increase their production to meet a growing demand. The importance of geothermal energy has grown steadily in the past decades relative to other primary energy resources, providing at present about 40 percent of the total energy consumed in Iceland. In this article the mature experience gained form exploiting Icelandic geothermal reservoirs is reviewed. The geological setting of the hydrothermal systems is described as well as its relation to the axial rift zones, which constitute the land expression of the Mid-Atlantic Ridge rifting system. Several field examples are presented, demonstrating the effects that exploitation has on temperature and pressure in the reservoirs. Some effects of volcanic activity on the geothermal reservoirs are discussed. Such influences are unavoidable where the geothermal potential depends on magma as a heat source. Recent reinjection field experiments and their effects on the characteristics of production wells are described.