Natural-state model update of Olkaria Domes geothermal field

Abstract

The Olkaria Domes geothermal field is located at the southeast edge of the Greater Olkaria geothermal area (GOGA). The area is bound approximately by the Ol’Njorowa gorge to the west and a ring of domes to the east and south of the field. The Olkaria Domes field is a high-temperature field with most of the wells producing two-phase fluid. This report aims at discussing and updating the natural-state model of the Olkaria Domes field reservoir, incorporating data from recently drilled wells. Several 3-D natural-state numerical models of the entire GOGA geothermal system have been developed, the first in 1987 by G.S. Bödvarsson and K. Pruess. Downhole profiles of temperature and pressure in the wells were interpreted to obtain the natural state of the reservoir in the wells’ locale. Previous work was incorporated and an inclusive model developed that forms the basis of a simple numerical model for the natural state that could provide the standard, pre-exploitation natural state of the Olkaria Domes field reservoir. In this report, the main focus will be on updating the natural-state model of the Olkaria Domes field, equivalent to the undisturbed formation before exploitation of the resource began. Previous models have been developed, the latest completed in 2012 by the Mannvit/ÍSOR/Vatnaskil/Verkís consortium.