Packers – Retrievable - Production
The Halliburton ACH packer is hydraulically set and is designed as a cut-to-release tool. The packer is designed to have multiple bores or can accommodate control lines internally.
It can be made to be a shear to release packer or a cut-to- release if used in high pressure environments.
A straight pull can be used to release the packer or the packer mandrel can be cut allowing the packer and tailpipe to be retrieved as a unit.
Hydraulic-set packers have a bidirectional slip system that is actuated by a predetermined amount of hydraulic pressure applied to the tubing string. To achieve a pressure differential at the packer and set it, a temporary plugging device must be run in the tailpipe below the packer.
The applied hydraulic pressure acts against a piston chamber in the packer. The force created by this action sets the slips and packs the element off. Some models have an atmospheric setting chamber and use the hydrostatic pressure of the well to boost the packoff force.
Regardless of design, all of the force generated during the setting process is mechanically locked in place until the packer is later released. Once the packer is set, the tubing may be landed in tension (limited by the shear-release value of the packer), compression, or neutral.
Because no tubing manipulation is required to set a hydraulic packer, it can be set easily after the wellhead has been flanged up and the tubing has been displaced. The hydraulic-set single-string packer is ideal for highly deviated wells in which conditions are not suitable for mechanical-set packers.
Special considerations include the following:
- Well stimulation must be planned carefully to avoid premature shear release of the packer.
- Maximum tensile capabilities of the tubing string when selecting the shear-release value of the packer are required.
- A temporary plugging device must always be incorporated below the lowermost hydraulic-set packer to facilitate hydraulic setting of the packer.
The RH series packers are primarily used as production packers and can be set on wireline or on tubing. When set on tubing a wireline-set positive plug must be set below the packer. Pump pressure is then applied to set the packer.
An alternative is to install a catcher sub below the packer which serves as the receptacle for a ball which is dropped down the tubing. After a few minutes the ball is in the catcher sub and pump pressure can be applied to set the packer.
The packer is unset by applying a pull of approximately 30,000 lbs above observed string weight. If the packer has been in the hole for a while or is in a deviated well, plan to use more than 30,000 lbs to unseat the packer.
This type of packer must be run in the hole at a conservative speed since it can be prematurely set by differential pressure which can be created if it’s run in the hole too fast.
After the production packer has been successfully set and the tubing/seal assembly in installed, the packer should be tested.
Generally the packer is tested “above and below.” The lower seals are tested by applying pressure through the tubing which will manifest below the lower seals.
The upper seals are tested by applying pressure through the casing which is ultimately applied to the upper seals.
Failure of either test usually results in pulling the packer. It can then be redressed on the surface, re-run and tested or another packer can be run and tested.
A continually failing packer may indicate a “bad” spot in the casing. If this is suspected, the packer may have to be set at a slightly shallower or deeper depth is possible.