Well test analysis of HGP-A

Abstract

Since the successful initial flashing on July 2, 1976, HGP-A has undergone five flash discharge tests with the longest duration of 42 days. Production records including wellhead pressure and temperature, production rate and steam quality were kept for drawdown analysis. After two of the discharge tests, Kuster pressure bomb was lowered to the bottomhole repeatedly to record pressure data for buildup analysis. Initial analysis of the drawdown and the buildup tests indicates the Kapoho Geothermal Reservoir where HGP-A is located seems to be tight in formation with possible severe mud damage in the well. The Reservoir also appears to be a liquid dominated system but with two phase flow during the discharge of HGP-A. Evidence of this claim will be presented in this paper. The pressure drawdown and buildup analysis were performed with the traditional single phase petroleum reservoir engineering techniques as modified when necessary. Attempts will be made in this paper to indicate the validity of this approach to a two-phase production formation.