RISK ASSESSMENT OF TECTONIC STRUCTURES - RELATED TO RESERVOIR LEAKAGE AT TENDAHO RESERVOIR; AFAR DEPRESSION, NE ETHIOPIA
Ten parameters were considered for the risk assessment of the tectonic structures (unforeseen geological conditions during the feasibility stage) related to the reservoir leakage: Tectonic Parameters – tectonic status Ts, tectonic regime Trr, tectonic history Th, aerial extent Ex, cross cut index Cci; and External Parameters – hydrogeology G, proximity P, relative position Ps, elevation difference Ed and hydraulic pressure Hp. Semi-quantitative and qualitative approaches of simple averaging, pairwise comparison and analytic hierarchy processing were applied to analyze the risk level of the tectonic structures. Tectonic structures, which are very close to the proposed reservoir, formed by extensional tectonic activities, higher aerial extent and cross cut index, are very high risks concerning the reservoir leakage. The risk of the reservoir leakage was estimated for the worst and average scenarios as 25.4m3/s and 2.4m3/s, respectively.