Evaluation and Integration of Reservoir Tracer Results in Optimizing Reinjection Strategies

Abstract

Reinjection (RI) returns or the inflow of injected brine is one of the dominant reservoir processes inherent in the Southern Negros Geothermal Production Field (SNGPF) in the Philippines. Previous studies have already shown that RI returns, when optimized, can provide artificial recharge and act as pressure support to sustain field production. Conversely, when uncontrolled, RI returns can cause severe cooling, resulting in well output decline or worse, non-commercial wellhead pressures in affected production wells. Reservoir tracer tests using Naphthalene Disulfonate (NDS) have been conducted to understand the impact of RI returns. This paper will present updates on the several tracer tests done in SNGPF in the span of 17 years and how the data was used to evaluate RI impact by simulating cooling predictions at different RI loadings for optimized reservoir management. The outcome is a well-understood connection between the reinjection and production sectors amidst a dynamic reservoir environment and a sound basis for an effective reinjection strategy.