| 摘要 |
A control circuit for a coiled tubing injector includes a circuit control ler (14). One or more counterbalance valves (3) may be responsive to the cir cuit controlier to prevent the tubing string from descending into the wellbo re during rate of penetration movement. In one embodiment, a control valve ( 4) allows fluid to flow through a bypass line around the counterbalance valv es when drilling in a weight-on-bit mode. Other hydraulic control circuits a llow for the release of fluid pressure to control the injector hydraulic mot or. In yet another embodiment, the control circuit regulates power to an ele ctric motor of the injector.
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