Caged Fullbore flowmeters (CFBM) have a spring-loaded cage that centres the spinner in the middle of the flow and supports tool weight in deviated wells. There are 3 arm & 6 arm versions available from GE’s Wireline product line. A large diameter impeller measures flow rates with coverage across the full bore of the casing. The spinner runs on precision roller bearings and its rotation is sensed by zero drag Hall-effect sensors. The signal from the sensors is converted into a flow rate measurement. The low mechanical threshold of these spinners enables them to be used in low flow rates; normal output is 10 pulses per revolution with directional indication.
Fullbore flowmeters are run in combination with either a Capacitance/Temperature/Flow (CTF) tool, or a dedicated electronics cartridge (CFBE).
The continuous flowmeters either have jewelled bearings (CFJM) or roller bearings (CFSM). The jewelled bearing flowmeters typically have better (lower) thresholds, while the roller bearing flowmeters are a little easier to maintain. Additionally, some continuous flowmeters have a ported shroud, which may make them less likely to trap debris.
Continuous Flowmeter Spinners are run in combination with either a Capacitance/Temperature/Flow (CTF) tool, or a dedicated Electronics cartridge (CFBE or CFJE, depending on whether the bearings are roller or jewel).
Capacitance Temperature Flowmeter
The Capacitance Temperature Flowmeter (CTF) combines three sensors - capacitance water holdup, temperature, and flowmeter - within a single tool. Consequently all three measurements are taken from the same depth in the well, unlike the sensors on a standard PL string that are a much greater distance apart.
Interchangeable spinner mechanical sections are fitted to the bottom of the CTF; dual magnets and Hall effect sensors detect the rotation of the impeller. The signal response is converted by the flowmeter electronics, within the CTF, and output as spinner velocity.
All of these flowmeters use GE’s proven Ultrawire toolbus, which enables them to be combined with other GE wireline logging tools.