Resistivity structure of Paka geothermal prospect in Kenya

Abstract

The resistivity structure of the Paka prospect was studied in order to give a structural image of the underground from data taken at the surface. Electrical resistivity is strongly affected by geothermal processes. An increased fluid content due to fracturing and the development of more conductive alteration clay minerals, can give rise to electrical resistivity contrasts which, with reliable mapping, can increase the chances of discovering geothermal resources and define the extent of a geothermal reservoir. This is done through imaging the controlling structures of geothermal systems, and locating the characteristic permeable fracture zones. Due to the presence of hot rocks and saline hot waters, geothermal areas tend to have low resistivity. In this report about the Paka prospect, indications are of the existence of a high-temperature geothermal system assuming the resistivity structure is in equilibrium with the alteration mineralogy and present day rock temperatures. It is presumed that the reservoir zone, which is expected to consist mostly of resistive minerals such as chlorite and epidote, will exhibit temperatures above 230ºC.