Joint 1D inversion of MT and TEM data from Menengai geothermal field, Kenya

Abstract

With an estimated geothermal potential of 10,000 MWe, Kenya has so far managed to develop slightly above 200 MWe and additional 280 MWe are on course. The Menengai volcanic system and caldera on the East African Rift is in a very strategic position for tapping geothermal energy. Understanding the resistivity structure of Menengai geothermal field should give a good understanding of the subsurface and enhance the possibility for the exploitation of this abundant geothermal resource. The subsurface was imaged using resistivity methods namely: MT and TEM. The resistivity structure of Menengai revealed four major resistivity layers. These layers are: a high-resistivity surface layer extending to a depth of about 300 m below the surface; a low-resistivity anomaly considered to be the cap-rock of the Menengai geothermal system, with a layer thickness of more than 700 m; a high-resistivity core which runs from a depth of 1600-3000 m, which is interpreted as the reservoir; and further below it, a low-resistivity zone which is interpreted to be the heat source. Temperature measurements from a well drilled to a depth of 2100 m correlated very well with the resistivity structure of Menengai.