| Abstract |
The Tendaho geothermal field is located in the Afar triangle (Northern Afar) about 650km northeast of Addis Ababa within Dupti cotton plantation. The Afar triangle is an area of active extensional tectonics and basaltic magmatism from which the Gulf of Aden, the Red Sea, and the Ethiopian rift systems radiate. Normal faults and open fissures are the principal elements of the Afar tectonics. In the Tendaho geothermal field, three deep (1811m-2100m) and three shallow (466m-516m) exploratory wells were drilled, four of which (one deep and three shallow wells) were found to be potentially productive. These productive wells supply sufficient steam to produce about 3 MWe. The main objective of the present study is to assess the genetic relationship of the deep and shallow Tendaho geothermal wells with the hot springs present in and around the project area. A plot of Cl-HCO3-SO4 has indicated that waters from the deep Tendaho geothermal wells are a Na-Cl, neutral-to-alkaline geothermal water, whereas the waters from Alalobeda hot springs have similar composition with slightly higher content of SO4. Application of various solute geothermometers has demonstrated that the average reservoir temperature of the deep Tendaho geothermal wells is in the range of about 220 C-270 C. Similarly, the temperatures of Alalobeda hot springs are in the range 150 C-220 C. The waters from the deep Tendaho wells were found to be in equilibrium with the reservoir rocks at a relatively higher temperature of about 240 C compared to the Alalobeda hot springs. |