The flowmeter measures the velocity of well fluids using a turbine (spinner) impeller. The higher the fluid velocity, the faster the spinner rotates. Knowing fluid velocity and tubing size, volumetric flow rate can be calculated. There is a wide range of flowmeters available, selection depending on several parameters including completion size, expected phases, flow rate and the potential for debris. The main spinner is placed at the bottom of the toolstring.
The spinner is continuously rotating and is used in both tubing and casing. It is more robust and can be used in wells where debris such as sand may impede the impeller blades. The threshold is lower than the caged spinner, and is therefore suitable for logging in lower fluid velocity wells.
Depending on tool size.