Application of Geospatial Technologies in the Selection of Suitable Geothermal Well Sites

Abstract

The study applied geospatial techniques to establish favorable areas for geothermal well siting in the Eburru Volcanic Area, Nakuru County. The study’s main objective was to apply remote sensing and Geographic Information Systems (GIS) to select suitable sites for geothermal wells. The specific objectives of the study involved the use of GIS multi-criteria evaluation and weighting of the distinct data layers (factor maps) for development of a final geothermal well suitability map. A suitability map was created by weighting and overlaying geothermal factors from three disciplines, namely: geology (faults, eruption centers, and dykes), geochemistry (altered grounds, fumaroles, hot grounds) and thermal factors (satellite land surface temperature, heat loss measurements). Environmental constraints such as built up areas, forest cover and riparian area (lake) were buffered, overlaid and filtered over the combined suitability map to establish a final suitability model. The methodology employed a multi-criteria approach using weighted overlay analysis, Boolean logic methods that supports conventional field based well site selection methods such as geology, geophysics and geochemistry. The results of the final suitability map was a classification of the study area into three primary regions namely; most suitable area, moderately suitable area and the least suitable area. Areas near Eburru trading centre, Thome (Northern region) and Badlands rift axis were found to be most suitable. The central and western regions of the study area were deemed to be moderately suitable. North Eastern zones (near Gilgil and Kikopey towns were found to be the least suitable. The study recommended the adoption of the technique in well siting activities.