What Does Coiled Tubing (CT) Mean?
Coiled tubing (CT) is a continuous flexible length of steel or composite tubing of diameter 1-3.25 inches that is wound around large reels to be transported to the job site. CT is used in coiled tube drilling (CTD) operations and comes in a coiled tubing unit with the reel, an injector, power supply, well-control stack and control console. CT is basically used for intervention in oil and gas wells and sometimes for drilling small diameter, shallow wells.
The CT can also be used to pump chemicals through the coil, wellbore cleanout, logging, sand control, well circulation, nitrogen kickoff and well perforation.
Trenchlesspedia Explains Coiled Tubing (CT)
CT is inserted into the existing production string in the wellbore by unwinding it from the reel and straightening it. Unlike conventional straight tubing, CT doesn't have to be screwed together as it comes in a long seamless length welded longitudinally. It also doesn't require a workover rig because the insertion is done during the production phase making it time and cost effective because instead of removing the tubing as is done by workover rigs, CT is inserted into the tubing against the well pressure during production.
Since CT is done on live wells, there are other operations such as well cleanout, well perforation and retrieval and replacement of equipment that can be carried out. Downhole measurements can be taken in real time which can be used for logging operations and treatment of wellbores.
Enhanced oil recovery processes (EOR) such as hydraulic and acid fracturing can also be done using CT.