Interpretation of Interference Test Data from Olkaria North East Field

Abstract

A multi-well interference test was conducted in the Olkaria N.E. geothermal Jield from November 1993 to April 1994. The test involved three production and three observation wells. The pressure drawdown in OW-707 was 0.2 bars after 125 days while in OW-724 was 0.47 bars after 104 days which is an indication of lateral communication between wells in this part of Olkaria N.E. Jield. The high transmissivity (kh) calculated for the reservoir using line source solution for the analytical inJnite acting model suggest the existence of high permeability flow channels through which fluids are transmitted within the reservoir. The pressure response in OW-707 suggest that the double porosity model might give a good match to the data. The storativity values from this tests were one to two orders of magnitude higher than those from type-curve matching of single well pressure buildup and suggest that part of the shallow reservoir comprises of two-phase boiling zones. Superposition of the pressure drawdown response in the monitoring wells indicated that the ivells were in communication with apressure support boundaiy.