RESERVOIR RESPONSE AND BEHAVIOR TO FTVE YEARS OF EXPLORATION OF ALBAY, PHILIPPINES THE BACON-MANITO GEOTHERMAL PRODUCTION FIELD

Abstract

Large scale exploitation of the Bacon-Manit0 geothermal production field commenced after commissioning the first 110-MWe power plant
(BacMan 1) in September 1993 and the 20-MWe Cawayan modular plant (J3acMan 2) in March 1994.The BacMan 1 power plant utilizes fourteen
production wells and the separated brine is injected into three injection wells located northwest of the production sector. The BacMan 2 modular plant in Cawayan is supported by four production wells and two injection wells in the southwest portion of the field. The other 20-MWe Botong modular plant was commissioned in April 1998, utilizing the remaining
production wells dnlled in the BacMan 2 area. The five-year behavior of the entire BacMan field is shown in various parameters as pressure,
temperature, and enthalpy. The field is divided into six sectors, each responding distinctively to production. There is a wide range of pressure
drawdown measured across the field, indicating non-uniform field-wide permeability distribution. The measured pressure decline closely agrees with the enthalpy rise in most production wells. The pressure trend also infers the degree and direction of recharge to the production sector. The enthalpy increase favors a rise in the field steam supply and a reduction in the brine flow. No direct connection between the production and reinjection sectors has so far been established. Several operational problems
encountered during the five years of field exploitation are also discussed and solutions to these reservoir management problems are presented.