Multi-criteria suitability analysis for optimal siting of a geothermal well: case study of the greater olkaria geothermal area (goga)

Abstract

In this study, the focus was on the applications of Geographical Information Systems (GIS) as a decision support system in geothermal resource exploration in the Greater Olkaria Geothermal Area (GaGA). The main objective of the project was to demonstrate how GIS can be applied in Geothermal well siting, making use of data sets from three key Geo-scientific fields- geological, geochemical and geophysical disciplines. Specific objectives included the determination of key factors in each of the geo-scientific fields that will be used in generation of suitability maps for each of the three fields. The three individual suitability maps were then integrated in ArcGIS 10.1 and used to generate the final geothermal well-site suitability map. The methodology employed included determination of various factors for each of the three involved Geo-Scientific fields and a criterion for suitability was determined for each of the factors. Results of all factors for each of the disciplines were overlaid and a suitability map for each of the three fields was generated. The final Suitability map for geothermal well siting was obtained from the results of integration of the three suitability maps. 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. The results of the study were compared with results obtained by current exploration methods employed by KenGen at Olkaria. On numerous occasions, current methods have led to siting and consequent drilling of dry wells. The studied approach aimed at avoiding location and drilling of dry wells as it was inclusive of a more thorough approach at exploration stage as opposed to the current methods employed by Kengen. The study recommends adoption of this criteria by the management at KenGen as it guarantees accuracy and an easier decision making process for sustainable location of well sites by effectively making use of GIS as decision support system.