ACCURACY AND RELIABILITY ANALYSIS OF TRACER FLOW TESTING IN GEOTHERMAL SYSTEMS

Abstract

As a critical resource management tool, tracer dilution techniques have been used to measure steam and brine flow and total enthalpy in geothermal industries for many years. Standard operations have become part of a routine monitoring program in many geothermal fields throughout the world. Different types of tracer for gaseous and aqueous phases have been developed and used in many different geothermal fields. Tracer injection equipment, sample collection systems and tracer analyzing methods have also been developed and gradually improved over past decades. The accuracy and reliability of testing results vary depending on types of tracer, injection and collection techniques, tracer analysis methods, and testing operation procedures. This paper summarizes our many years’ experienceon utilizing sodium benzoate and isopropyl alcohol as tracers for flow testing in geothermal systems in New Zealand and overseas and analyses the accuracy and reliability of the available testing results.
Single gaseous and aqueous tracers have also been used to measure steam or water flow rates in single phase pipelines to verify permanent flow meters at geothermal plants. An innovative tracer testing procedure to evaluate the performance of steam purifiers has also been developed with consistent results achieved. Particular emphasis will be placed on quality control system to ensure more accurate and reliable results are achieved.