Pressure Differential Devices for Measuring Total Mass Flow Rate and Enthalpy in Two-phase Geothermal Pipelines

Abstract

Mass flow rate and enthalpy are critical parameters that need to be measured on a real-time basis during production from two-phase geothermal systems as well output can significantly change with time, due to a host of reservoir and wellbore events. Existing field measuring techniques are not capable of accurately determining in real-time the enthalpy and mass flow rate from individual geothermal wells in production without using wellhead separators. A new method for the real-time measurement of both enthalpy and mass flow rate using pressure differential devices (such as orifice plates, Nozzles and Venturi meters) has been developed using data from multiple geothermal fields in Indonesia and New Zealand. This measurement technique can be applied cost-effectively with high accuracy (1-2%) and repeatability for a wide range of geothermal two-phase flow conditions. Furthermore, the new technique can be coupled with other enthalpy measurement devices including the micro-lip pressure testing techniques.