Well Testing and Reservoir Engineering Studies at the Tendaho Geothermal Field, Ethiopia

Abstract

In this paper the 6 wells drilled in the Tendaho geothermal field are briefly described. Formation temperatures and initial pressures for each well are estimated and a conceptual reservoir model presented. The Tendaho reservoir is divided into a shallow sedimentary reservoir of 220-250oC temperature and a deep one in volcanic basalts, ranging from 220-270oC in temperature. Inflow comes from depth in the east and flows diagonally to the surface, causing reversed temperatures in the present wellfield. Production data analysis indicates permeability-thickness in the range of 3-10 Dm in the shallow reservoir. A wellbore simulator study show that the present wells maintain high flowrates despite either a 5 bars reservoir drawdown or a 20oC reservoir cooling. Both volumetric reservoir assessment and TOUGH2 reservoir model indicate that the present wellfield can sustain 70 kg/s production rate for 20 years.