Primarily used during completion or well intervention, a plug is required to isolate a part of the wellbore from another part; for instance, when a job is carried out on the upper section of the well, the lower part of the wellbore must be isolated and plugged, i.e. zonal isolation in a well. Plugs can be temporary or permanent; the former can be retrieved, whereas the latter has to be drilled out. There is a number of types of plugs, namely bridge plugs, cement plugs, frac plugs, and disappearing plugs. Plugs can be set using a wire-line, coiled tubing or drill pipe.
Used during completion, a packer serves the purpose of sealing off the area between production tubing and casing and the wall of the wellbore. A primary reason to run a packer is to prevent formation fluids going up the wellbore, which could otherwise damage the casing or other formations in the well, be it below or above the production zone. The packer can also serve as an anchor point for production tubing.
Packers can be retrievable or permanent (production). Retrievable packers are used in a less challenging and less hostile environment and where frequent well re-completion is required, or when there is another activity carried out in a well, such as well stimulation or cement squeezing, or to isolate leaking zones. Permanent packers are required at all times when a well is producing, and are generally technically superior and offer far better performance capabilities than retrievable packers.
Production packers are set just above the perforation area and very close to the bottom of the production tubing. In a multi-zone well completion, production packers are set between multi zones. In injection wells, packers isolate the areas into those in which injection fluids are pumped, hence service packers may be used as well.
There is a number of various technologies used in packers for various applications, namely Swellable Packers, Inflatable Packers, Hydraulically Set Packers, Intelligent Completion Packers, Sand Control Packers, Dual String Packers, Sealbore packers and Mechanical Packers.
Production tubing string or a wire-line is used as the deployment tool to run any packer.