Two-Phase Flow Measurement of Geothermal Fluid

Abstract

Online, real-time, two-phase fluid measurement of mass flow rate and enthalpy are necessary and important for monitoring individual well performance and for optimum geothermal reservoir management. Existing research on two-phase flow measurements in geothermal applications was examined and the objectives of the work are outlined A detailed evaluation of well discharge prediction and stimulation methods are provided first to ensure that the tested wells are self-discharge before two-phase flow measurement installations. Data from several geothermal fields from around the world were used to validate the optimum and most simple methods for discharge predictions and applying stimulation techniques. The extensive field-testing of both two-phase orifice plate and Load Cells was undertaking on large diameter pipelines (≥10 inch) at several fields in Indonesia and New Zealand is described. Details of equipment design, site layout, installation and test procedures are also covered. The field-testing data were used to develop new accurate correlation for measuring the two-phase mass flow rate using concentric sharp-edged orifice plate. Also, a new model was developed and validated for predicting the net pressure drop across the two-phase orifice is given. A comprehensive computational fluid dynamics (CFD) modelling study is presented for six types of flow meters: concentric, top eccentric, bottom eccentric and segmental orifice plates along with Nozzle and Venturi tubes. The CFD results were calibrated against the field-testing data of concentric orifice plate first and then used to predict and compare with the other pressure differential flow meter. The analysis of Load Cells measurements from field-testing was then examined. Liquid velocity and enthalpy measurement are quantified using different modelling approaches. The results and technical challenges with the recommendations were explained constructively. A novel technique for measuring both mass flow rate and enthalpy of two-phase geothermal fluid in real-time is presented. This new flow meter has good accuracy with less noise for a wide range of wells output and pipeline size range, which is very useful for the geothermal industry. The concepts for further research and field experiment are also described to enhance the results of the present work.