APPLICATION OF 2-D MAGNETOTELLURIC DATA IN INVESTIGATION OF GEOTHERMAL ANOMALY IN EBURRU GEOTHERMAL FIELD, KENYA.

抄録

To study the occurrence conditions and locations of geothermal bodies in Eburru geothermal field, Kenya, magnetotelluric investigation was conducted to detect promising zones for geothermal development by studying the detailed subsurface resistivity distribution on parallel profiles. In particular, delineating the locations of faults and fracture systems by studying resistivity discontinuities, and the cap rock zones of geothermal reservoirs by studying low resistivity zones at relatively shallow depths, are important in selecting future drilling targets.MT data analysis was done to derive a dataset suitable for defining the resistivity model of the Earth from the observed MT data. Dimensionality analyses demonstrated that the MT data can be interpreted using two-dimensional approaches, but some localized 3-D effects are seen. The inversion of data into resistivity model was performed using Occam 2D and the resultant 2-D resistivity sections were interpreted as to identify the components of Eburru geothermal system. The four profiles analysed revealed a structure which can be interpreted as potential path way of low resistivity used by geothermal fluid to migrate to the surface. An exploratory well drilled near the structure in Profile 2 confirms the occurrence of high temperature.