The impeller flowmeter provides a continuous log of vertical fluid velocity within a borehole. Two sizes of high-sensitivity probes satisfy most borehole-size requirements and expected flow rates.
Principle of Measurement:
The probes are equipped with lightweight helical impellers mounted on double sapphire bearings. The impellers contain magnets which actuate Hall-effect switches within the probe to detect impeller rotation. Separate log channels record the time of rotation according to fast and slow timebases for improved resolution at high and low flow rates. Uphole and downhole rotations are distinguished within the sonde.