| 摘要 |
An apparatus for use in circulating cement in a casing in a wellbore is described having a first component such as a sensor disposed on the casing and a second component such as a detectable device disposed at a fluid interface formed between the cement and a fluid. The sensor may be a sensor coil mounted on the perimeter of the lower end of the casing, while the detectable device may be a transponder capable of emitting Radio Frequency Identification signals to the sensor to signal its arrival at the lower end of the casing. The transponder may be encased in a protective covering. Also described is a method of cementing a casing utilizing a first component such as a sensor disposed on the casing and a second component such as a detectable device disposed in the cement. Further, a system for use in detecting the launching of a device, such as a wiper plug or a sealing ball, is described having a first component, such as a detectable object disposed within the device, and a second component, such as a sensor. The sensor may be a sensor coil, while the detectable object may be a transponder capable of emitting Radio Frequency Identification signals to the sensor to signal its arrival adjacent the sensor. The system may be used with a concrete head or with a sealing ball injector. A method oflaunching the devices is also disclosed.
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