Swing-Rod Flowmeter - A New Downhole Flow Measurement Technology

Abstract In the process of separate layer injection and production, downhole flow measurement is always a difficult problem and is the bottleneck for realizing flow automatic control. To solve this problem, a new swing-rod flowmeter is disclosed in this paper. The structure of the swing-nod flowmeter mainly comprises a sampler, a swing-rod, a displacement transfer rod, a target and a sensor etc. A hollow swing-nod which inserted in the measuring tube is used as the sensitive element. At the end of swing-nod is a sampler which is used as the sampling element of the fluid to be measured, Eddy current displacement sensor is used as sensitive element to measure the displacement of the target. The working principle is: when fluid flowing thought the sampler, a displacement of the swing-nod is produced. The displacement reflects the rate of flow. The displacement of the swing rod is transfer to the electronic cabin by the transfer rod, by measuring the displacement of the target mounted on the transfer rod, the quality of the flowing fluid can be measured accurately. Downhole flowmeter is required to be with high working pressure, long service life, strong anti-interference ability and small volume. Especially for the battery-powered metering system, low power consumption is necessary for flowmeter. The Swing-rod flowmeter presents excellent performance, the working pressure can reach 70Mpa, range ratio is 30, the minimum flow measurement is 0.5m3/day, and measurement precision is 3%. The advantages of the swing-rod flowmeter include: high working pressure, low power consumption, compact structure, wide measurement range, convenient range adjustment and strong anti-interference ability. The Swing-rod flowmeter is suit for downhole flow measurement. In one hand, the pressure is very high in the downhole environment, in the other hand, small flow measurement require high sensitivity. The existing flow measurement technology is hard to be used in downhole flow measurement directly. Swing-rod flowmeter provides a perfect solution for downhole flow measurement and flow control; it has been successfully used in separate layer water flooding system.