Interpretation of Continuous Measurement of Steam and Water Flow Rates at a Production Well 2H-21, Hatchobaru Geothermal Field, Japan

Abstract

The continuous measurement of steam and water flow rates at a production Well 2H-21, at Hatchobaru geothermal field, Japan with a newly developed measurement system to evaluate and understand unsteady state behaviors of well characteristics is carried out. The measurement apparatus consists of pressure sensors, water level sensor and a PC to store the measured data. The data are recorded every second for the pressures at upstream of the orifices, the pressure drops at the orifices, the pressures at the separators, and the water level at weir box. The atmospheric pressure is also measured daily. The degree of valve opening is changed three times during the measurement and the duration of respective wellhead valve operation for controlling flow rate affect the flow to stabilize in wellbore. Quick valve operation causes longer period of stabilization and produces impulse response of flow rate soon after the valve operation stopped. The fluid flow requires shorter time to stabilize for closing valve operation compared with that for opening valve operation. After changing the wellhead pressure, the steam flow rate stabilizes quickly while the water flow rate shows a gradual change.