First, a coiled tubing unit (CTU) central to CT surface operations consists of a reel that holds a continuous length of flexible steel pipe. After that, the tubing is deployed downhole by spooling it off the reel and guiding it through a gooseneck, which directs the CT downward to an injector head. It becomes straight before it enters the borehole.
Right after the end of the operation, the flexible tubing is taken out of the well and spooled back onto the reel using a high-pressure swivel joint on the reel hub that allows for the pumping of fluids while the reel rotates. Throughout the process, the CT operator controls the movement and depth of the CT string from the CTU control cabin using a hydraulically driven injector head.
It is important to note that a dynamic seal around the tubing string is provided by a stripper assembly beneath the injector head, which is crucial for running the CT in and out of live wells. A secondary and backup pressure-control system is provided by a blowout preventer assembly positioned between the stripper and wellhead.
The CTU control cabin oversees and coordinates the entire process of managing the deployment and retrieval of flexible tubing during CT surface operations, making it a crucial component in the overall process.