There are a number of problems that can develop in a producing well that can negatively affect operations, production and ultimately revenue generation. Examples include: failure of mechanical equipment, changes in production characteristics, plugging and increases in injection pressure. After a well goes into production, these events may occur, requiring modification of the well in order to achieve optimal production (called well intervention).
A cost- and time-effective solution for well intervention operations employs coiled tubing. Instead of removing the tubing from the well, which is how work-over rigs fix a problem. Coiled tubing is inserted into the production tubing against the pressure of the well and during production.
The coiled tubing is a continuous length of steel or composite tubing that is flexible enough to be wound on a large reel for transportation. The coiled tubing unit is composed of a reel with the coiled tubing, an injector, control console, power supply and well-control stack. The coiled tubing is injected into the existing production string, unwound from the reel and inserted into the well.
All performed on a live well, there are a number of well intervention operations that can be achieved via coiled tubing. These include clean-out and perforating the wellbore, as well as retrieving and replacing damaged equipment.
Additionally, some advances in coiled tubing allow for real-time downhole measurements that can be used in logging operations and wellbore treatments. Enhanced Oil Recovery (EOR) processes, such as hydraulic and acid fracturing, can also be performed using coiled tubing. Furthermore, sand control and cementing operations can be performed via coiled tubing.