| dc.description.abstract | This project describes the analysis carried out in the Olobanita well-field, Nakuru county,
Kenya, using geophysical surveys and geologic logs with an aim of investigating the
geometry and lithology responsible for collapsing of boreholes in the Olobanita well field.
This has been a major setback in an effort to provide water from the ground water rich basin.
In this case therefore, the project employ geophysical surveys and geologic logs to
explicitly investigate and characterize the subsurface responsible for the drilling menace
recently encountered by Zhonghao Overseas Construction Engineering Company Ltd.
Geophysical surveys used include, Vertical electrical sounding (VES), Electrical resistivity
imaging (ERI) and ground magnetic measurements. The vertical electrical sounding was done
using the SYSCAL R2 equipment in the Schlumberger electrode configuration, electrical
resistivity imaging involved the SYSCAL R1 switch 72 resistivity equipment and magnetic
measurements utilized the proton precession magnetometer.
Results obtained from the geophysical survey were then analysed and related to borehole
log information of Olobanita well-field, this has revealed some correspondence between
lithostratigraphic units and resistivity values.
From the results obtained it is true that the prominent fault systems within the basin
alongside the heterogeneity of the ground coupled with the soft loose volcano-sediments are
greatly responsible for the collapsing of freshly drilled boreholes in the area. Finally several
recommendations are made to reduce or to completely avoid caving in of boreholes during
and after drilling | en |
