Reservoir Tracer Testing in the Maibarara Geothermal Field, Philippines

Abstract

The Maibarara Geothermal Power Facility (MGPF) has a combined installed capacity of 32 MW from its two geothermal plants. The first 20 MW unit started commercial operations in 2014 and the second 12 MW in April 2018. A reservoir tracer injection study using Naphthalene di-sulphonates (1,5-NDS and 2,6-NDS) was conducted in 2016 after changes in well characteristics and field parameters were observed in one of the two production wells supplying steam to the first power plant unit. The objective of the tracer test was to validate injection fluid breakthrough in the production area and determine the geologic pathway for such connection. Results of the study indicated a previously unknown, direct but buried fault connecting the production to the injection wells that facilitates breakthrough in just one day from well RI-3 to PW-2.