Measuring two-phase flow in geothermal pipelines using sharp edge orifice plates

The measurement of the two-phase flow rate is very important for the geothermal industry. Among the many different measurement techniques available, the orifice plate stands out for its simplicity, low cost, and the ability to provide real time measurements. Several data sets from different geothermal fields in New Zealand, Indonesia, and the Philippines are used to evaluate existing correlations all of which are based on homogenous flow models. Then derive and test a new correlation based on separated flow model with time discrete liquid phase flow for a more accurate measurement of two-phase flow in geothermal pipelines using the orifice plate. The new correlation is now being implemented successfully in New Zealand and other countries.

► Measurement of two phase flow is very important for geothermal steam field management. ► Existing measurements techniques are reviewed and the advantages of the sharp edge orifice plate are presented. ► Existing two phase flow correlations using the orifice plate are examined using field data from several geothermal fields. ► It was demonstrated that none of the existing correlations can be universally applied without case by case calibration. ► A new time discreet model was developed and tested and is currently used by the geothermal industry.