Completion Expansion Packer
When wells use steam to enhance oil production, thermal expansion and contraction of the steel in these wells can cause many problems. The most common problem is the movement of casing and tubing that would otherwise be contained. Many of these wells use a completion packer, which are permanently set in the well. The completion tubing, connected to the packer and to the wellhead, must be able to expand and contract with temperature changes. Expansion joints are typically run within the completion tubing string to allow for this thermal movement.
Since many of the seals in packers and expansion joints are elastomeric materials, they eventually fail due to the extreme steam temperatures. Also, setting the expansion joints in the open position (cold) can be difficult using pup joints. If the required open amount is not achieved when being set, or the expansion joint fails to close/open when subjected to temperature changes, the tubing string will be damaged. Elastomeric materials need to be replaced with material that will survive high steam temperatures.
The Completion Expansion Packer (CEP) is a tool that combines the completion packer and the expansion joints, and uses only steel manufactured seals, that withstand the most extreme temperatures. When the well is drilled and the casing is run and cemented in place, a Polished Bore Receptacle (PBR) is placed within the casing string, located above the cementing floats. When the completion string is placed in the well, the CEP is run on the bottom of the completion string and landed inside the PBR joint. As the tubing expands and contracts, the CEP travels within the PBR maintaining a seal, even under movement.
The seals are preset at surface to a calculated setting, which will have to be overcome before movement of the seal within the PBR can occur. This calculated load is determined by the type of completion tools and tubing being used. This will insure that movement of the seals will take place, before damage can occur to the tubing string above the CEP. The CEP is designed with casing scrapers and corrosive materials to avoid seal sticking. The seals are preset with positive memory to enhance seal capability, even under movement.