The Olkaria qeothermal field has been under continuous development since 1970. A feasibil-itv study, completed in 1976, after six wells had been drilled and tested, indicated that development of the Olkaria field was feasible. Thefeasihilitv study was followed by production drill in o and the construction of three 15 ih generating units. The first unit was brought on stream in 3uly 1981, the second in December, 1932, and the third unit is scheduled to be completed in early 1955. The current output of 19 productive wells is equivalent to 46 the. 9 is t r i o u t i o n of fumaroles and resistivitv surveys indicate an areal extent of some 80 kin2 for the 9 l k a r i a geothermal field. Gas chemist r y of fumaroles indicates comparable under mound temperatures over the whole field, ZO0-25OoC. The capacity of the resource has been estimated to he 500-1000 MY, electric for a production Period of 25 years. Most of the drilling has been confined to a s m d l l part of the geothermal field. The maximum recorded downhole temperature is 339OC and temperatures follow the boil in a point curve with depth. A thin steam zone at 240OC is observed in the top of the reservoir at approximately 600-700 m depth. The reservoir fluid is dilute, of the sodium chloride type, contains chloride in the range of 200-7W oom. The reservoir rocks consist of a sequence of near horizontal lava s and tuffs of t r a c h y t i c composition, but basaltic andesites have also been identified. The drilled rocks at Qlkaria are of relatively low permeability, the average yield of sells being equivalent to about 2.5 Exploratory drilling is presently in progress in the Olkaria field, the aim being to locate new production areas Within the field. Three holes have been completed and the forth and last hole under the present plan is being drill e d .

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