FIELD-WIDE APPLICATION OF CHEMICAL TRACERS FOR MASS FLOW MEASUREMENTS IN PHILIPPINE GEOTHERMAL FIELDS

Abstract

Chemical tracers are widely utilized in Philippine geothermal fields to accurately measure the bore output of production wells, reinjection line flow
rates, and steam inlet rates to power plants. Based on these flow measurements, a production-injection well utilization strategy is formulated to optimize production and minimize reinjection fluid breakthrough to the production sector. The reservoir response to field utilization is fully assessed based on the total steam and brine flow measurements with
time and individual reinjection well capacity trends.

Recent on-line bore output measurements using sodium benzoate for brine flow and sulfur hexafluoride for steam flow demonstrated a good correlation with the James tube method for several production wells tested. Similarly, steam flow rates measured by tracer compared well with venturi flowmeter measurements at power plant inlets.

Magnesium chloride has been extensively used as a chemical tracer for reinjection water flow measurements by PNOC. These test results yielded close agreement with orifice plate flowmeter and spinner flow measurements. Other chemical tracers, such as sodium benzoate and sodium fluorescein, were compared with the magnesium chloride tracer and produced similar results. However, magnesium chloride is not a practical tracer to use for brine flow from high temperature two-phase production wells due to potential deposition of MgCO3 and Mg(OH)2.