Feed Sharing Limit for Geothermal Wells in Bacon-Manito, Philippines

Abstract

The point-to-point separation between wells that intersect similar feed zones is crucial during well-design preparations to eliminate the risk of production interference. When feed sharing occurs, the total output from the new well becomes less than expected. In some cases, this may lead to output decline of the adjacent wells. To eliminate or reduce risk of feed sharing, a minimum point-to-point separation of ≥ 300 m between wells along common feed zones has been implemented in designing Energy Development Corporation (EDC)-owned geothermal wells as adopted from a previous drilling interference study from one of its fields. However, given a finite resource area and the need to drill more wells to maintain and manage steam supply requirements to power plants, this separation has become a challenge to achieve. Therefore, it is the aim of this study to establish an optimum point-to-point separation along common feed zones for Bacon-Manito (BacMan) geothermal wells by assessing well production data from Pad 1 where a collapsing production well D is suspected to be sharing feed zones with other wells. The calculated optimum separations are validated for future well design considerations. Factors that possibly enhance or reduce feed sharing such as fault characteristics and reservoir rocks that are specific for the Bacon-Manito geothermal field are also identified. The methods utilized in this study will be further assessed for applicability in other EDC geothermal fields where optimum point-to-point separation as not yet been established.