| Title | Reservoir Tracer Testing in Maibarara Geothermal Field: Evolution of Maibarara’s Field Management Strategy |
|---|---|
| Authors | Michelle M. Visperas, Diana Lee O. Navarro, Arnold B. Sinogba, Joseph Nikko M. Mazaredo, Miguel B |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Maibarara Geothermal Inc. (MGI) operates a geothermal facility in Batangas, Philippines, with a combined installed capacity of 32 MW from two power plant units within a 9-hectare development area. Initially, the field relied solely on an infield reinjection system, which re-introduces separated brine near production wells to help maintain reservoir pressure. In 2016 and 2022, MGI conducted reservoir tracer tests to assess the performance and connectivity of this infield reinjection system. The tests involved injecting naphthalene di-sulphonate (NDS) chemical tracers, such as 1,5-NDS, 1,6-NDS, 2,6-NDS, and 2,7-NDS, into three (3) reinjection wells and monitoring their breakthrough in three (3) nearby production wells for a period of around 12 months. Results from both tracer tests showed varying degrees of connectivity—some wells exhibited rapid tracer returns within 1 day, indicating strong flow paths, while others showed delayed or minimal responses of as long as 335 days from injection, suggesting limited connectivity. These findings were instrumental in refining the field’s reservoir management strategy and led to the development of an outfield reinjection system, which was commissioned in 2024 to enhance fluid disposal and reduce thermal interference in production zones. This paper presents the tracer test results and discusses their implications for field and reservoir management. |