Workover well control. Part 4. Coiled-tubing pigs speed workover operations

Many workover operations can be completed quickly and efficiently by using coiled tubing instead of jointed tubing or conventional rigs. In general, coiled tubing is a continuous string of small-diameter tubing that can be run into the well without the necessity of making joint connections. The operations are safe, involve small amounts of rig time, and usually are more economical than other forms of concentric work. Coiled tubing work is usually conducted on producing wells, which necessitates pressure-control precautions. Applications for coiled tubing involve all aspects of workover operations except wire-line work. Coiled tubing can be used in initiating flow, cleaning out sand in tubing, and performing stimulation operations. In addition, drilling can be conducted with coiled tubing when down-hole motors are used.