Thermal Field in an Aquiferous Layer Behind a Vertical Heat Exchanger

Abstract

Accurate measurement of geothermal production fluids is of vital importance for both reservoir management of geothermal resources and for production utilization of available geothermal fluids. The metering of two or more flowing phases in a pipeline is inherently complex. Considerable research effort spanning decades has searched for a solution that had been elusive.

The New Energy and Industrial Technology Development Organization (NEDO) has initiated a research program titled "Development of Technology for Reservoir Mass and Heat Flow Characterization." As a part of the research project, Japan Petroleum Exploration Company, Ltd. (JAPEX) has contracted to carry out a research project titled "Development of the Two Phase Metering System".

At present, a system using separator is the most popular to meter steam and hot water volume continuously. But this system is so expensive that we can not set up at each well. Therefore, the purpose of this study is to measure of steam and hot water volume in tow-phase flow line of geothermal pipelines with high accuracy and low cost.

In the beginning, we had conducted a feasibility study of the two-phase metering system for low cost and easily maintenances. As the result of the feasibility study, it became clear that a vortex shedding low meter (VFM) combined with a dielectric steam quality sensor (DSQS) was the most useful and effective for tow-phase metering system. To clarify the usefulness of this system in a geothermal pipeline, we had carried out some field experiments at the Okuaizu geothermal field. Data collected by these experiments were compared with data obtained by tracer dilution method (TFT) which was accurate as same as the separator measurement. As the result of the experiments, we could confirm that DSQS and VFM could work in a tow phase flow so well. Also, the results of DSQS/TFT measurement were agreeable on two of three test runs, even when operated in a transitional annular and wavy stratified flow regime. From these experiments, the usefulness and effectiveness of this system were demonstrated in the geothermal field. However, another new technique will be required to protect scaling on these devices. To correspond to the scale issue, we will propose a scanning method by using a laser flow meter as a future work.