The Fluid Characteristics of Three Exploration Wells Drilled at Olkaria-Domes Field, Kenya

Abstract

Exploration drilling in Olkaria-Domes Field began in 1998 and three wells were drilled to completion. These were wells OW-901, OW-902 and OW-903. A mixed type sodium bicarbonate - chloride- sulphate water with dilute chloride concentration (chloride ~178-280 ppm) was discharged. The pH of fluids discharged tended to alkali (8.68 to 10.69) as sampled at atmospheric pressure. Carbon dioxide gas concentration in steam on average was high relative to that of the Olkaria East Field. A less mineralised water component is thought to exist in this field due to the wells being shallowly cased. Solute geothermometry offer a good estimate of temperatures where dilute fluids inflow into the wells between 1000m to 1200m. Gas geothermometry approximate to the deep temperature in the reservoir though these were less than measured temperatures at well bottom. Down hole temperatures ranged from ~240 0 C to ~ 340 0 C were encountered in the three wells. The well fluids have low to medium enthalpy.