Packers Retrieving Considerations

1. Release packer with minimum tubing manipulation, straight pull, or 1/3 turn release.

Many times well conditions or other downhole equipment in the string make it desirable to have the packer release with little or no tubing manipulation. Deviated holes are examples of the former, while the presence of eccentric gas lift side pocket mandrels or lengths of 1/4″ control line in the hole would be examples of the latter. A straight pull release mechanism is the most desirable option in most cases. These packers are usually shear pinned in the set position (exception –some tension set types). Another option is a minimum rotation type release (1/3 turn at the packer) that some retrievable have. Many seal bore type retrievable are released by straight tension but only after the production seal unit has been pulled. These packers require an additional trip with a releasing tool in order to pull the packer. However, no tubing rotation is required. A few special packers have also been designed and run that are straight pull release after a wireline sleeve has been shifted. This option is somewhat unpopular because the ability to pull the packer is dependent on wireline access to the packer. Lack of tubing access may very well be the reason for needing to pull the production packer in the first place.

2. Back up release capability, safety shear release, or rotating release.

Undesirable well conditions, unplanned production problems, and incompatibility with other downhole tools are all reasons that may make a backup release capability a needed feature. If the primary release mechanism cannot or does not function for some reason, such a feature becomes very important. At times, these possibilities can be anticipated and such a feature should hold a high priority in packer selection. The most common type of secondary release is by shearing shear pins or screws with a straight pull. However, rotation-type secondary releases have also been incorporated on some packers.

3. Tubing or packer retrievable with some fill, packer bypass or flush seal unit.

Some production operations may result in moderate fill in the casing above the packer. An example would be the production of a second zone above a single packer in the tubing/casing annulus. Produced fines from the upper zone may settle out on the packer top. In such cases, the packer should be placed as close as possible to the bottom of the upper zone or a sliding sleeve should be placed as close as possible to the packer top. However, even then some fines will remain and a bypass or pressure unloader is very useful to allow the tubing to casing circulation above the elements to remove the fines or debris. In permanent or seal bore type retrievable, a seal assembly can provide the same ability. This functions best when the seal assembly is equal to or smaller in OD than the tubing.

4. Equalize pressure on packer release, pressure unloader or separate seal unit.

When packers are run past moderate depths, it becomes possible or probable that considerable pressure differentials may exist across the packer upon release. If the operator does not load the tubing before release, the casing fluid pressure may be substantially higher than the pressure of the partially depleted reservoir being isolated. A differential from below may exist under other conditions if the isolated reservoir is charged by injection or is naturally over-pressured.

In either case, if a pressure-equalizing device of some type is not available, then there is a good possibility that packer release may be difficult, and/or the element package will be damaged in the releasing process. This is an especially important feature if the packer needs to be reset on the same trip. An option to the internal-pressure-unloader design feature is that the same equalization may be done by pulling the seal assembly out of a seal bore type retrievable packer.

5. Release the packer with no tubing trip, tubing connects directly to the packer.

As mentioned previously, some packers require a round-trip of the tubing in order to retrieve the seal assembly and re-run the pulling tool. This is not acceptable in certain instances. In some filed operations where regular workover is common, the economics of such pulling procedures could not be justified. In order to be able to pull the packer without making a tubing trip, it must be of the type that is designed to be threaded directly to the tubing and not the seal bore type retrievable that is attached to the tubing via a latch on seal assembly. The exception is the wireline release version previously discussed. Many of these thread-to-packer types may be modified with accessories so the tubing may be pulled separately from the packer and still retain the retrievability without a tubing round trip.

6. Easily milled packer, minimum mill distance, and non-rotating.

The needs for an easily and quickly millable permanent packer are obvious. Packer designs that make this possible include millable metal components, designs for minimum mill distances, designs for minimum milled OD’s, and anti-rotation locking features.

Vigor's packer series products are manufactured according to the high standards of API 11D1, and all packers from R&D to production to final delivery to customers are strictly controlled and documented to ensure that the quality of the products can meet the requirements of customers. If you are interested in Vigor's range of perforating guns, please do not hesitate to get in touch with Vigor's professional team for the best product support and technical support.