Initial conditions of wells OW-906A, OW-908, OS-910A and OW-914 and a simple natural state model of Olkaria Domes geothermal field, Kenya

Abstract

The Greater Olkaria geothermal area is divided into seven sectors. Currently, three sectors are generating about 202 MWe and production drilling for the Domes has been completed. Plans are now at an advanced stage to set up a 140 MWe power plant in the Olkaria Domes field. Systematic analysis of downhole temperature and pressure profiles, injection, fall-off and discharge tests has given the basis for a conceptual reservoir model for the Domes. The reservoir is two phase with the temperature following the boiling point curve; logging revealed temperatures of over 300°C in most of the wells at a depth of about 2000 m. The conceptual model shows that the Domes field has an upflow zone near wells OW-909, OW-910, OW- 915 and OW-915. Fluid flow appears to be generally from northeast to southwest and well OW-902 seems to have been drilled in an outflow zone. Well test analysis indicate transmissivities in the range 1.5-4.6 × 10-8 m3/Pa.s and effective permeabilities of 3.1-5.9 mD in the reservoir, with negative skin being observed in most of the wells. Injectivities of the wells range from 3.5 to 3.6 (L/s)/bar.