A simple geochemical prospecting method for geothermal resources in flat areas

Abstract In this paper a relatively inexpensive and efficient strategy for geothermal exploration by using geochemical prospecting tools to determine the placement of initial exploratory well(s) is proposed. The method involves categorizing the hierarchy of thermal manifestations from which the presence of a buried thermal anomaly can be identified in a given geothermal area, and then locating the centre of the thermal anomaly. This is done by using simple, easy to obtain data on the depth, temperature, and some common chemical parameters determined in wells of the shallow unconfined aquifer, from which thermal gradients can be calculated if the temperature of the local rainfall is known. The proposed strategy was applied by the author in Yemen; on a national scale in 2001–2006 ( Minissale et al., 2007 ), and a local scale in 2007–2010 in the Dhamar region ( Minissale et al., 2013 ). In the paper about the Dhamar area, briefly summarized here, how the placement of its first exploratory well was determined is described. The methodology proposed is particularly effective and convenient in developing countries, such as those located along the African Rift, e.g. Zambia and Malawi, where geothermal exploration is still in its infancy, and where waiting for expensive geophysical investigations might postpone the development of geothermal resources for decades.