The Petroleum Production System - Packer
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The packer 1 is a sealing device with a slip, cone, packing-element system, and body or mandrel.
Contributions
PetroWiki 1 defines the contributions of the packer in the petroleum production system as:
- Provides a seal between the tubing and casing
- Prevents downhole movement of the tubing string
- Supports some of the weight of the tubing
- Holds well-servicing fluid in the casing annulus
- Facilitate artificial lift through the A-annulus
- Protect the production casing from corrosion due to produced fluids and high pressures
- Can provide a means of separating multiple producing zones
- Allows the optimum size of well flow conduit (the tubing string) to meet the designed production or injection flowrates
Problem Areas and Solutions
- Packer seal failure due to 2
- Improper storage, handling, and installation. Common approaches to mitigate this involve
- Proper handling mechanism, training of staff and use of required equipments
- Abnormal operation factors. Common approaches to mitigate this involve
- Use of appropriate design safety factors
- Proper lubrication
- Carrying out tests on anticipated conditions prior to use
- Reduction in packer seal service life due to varying factors. Common approaches to mitigate this involve
- Increasing the hardness of the sealing material to improve resistance to wear
- Corrosion prevention measures
- Proper lubrication
- Operating outside design minimum and maximum temperature. Common approaches to mitigate this involve
- Seal design should accomodate for high temperature conditions
- Pressure. Common approaches to mitigate this involve
- Limit compression set
- Seal design should accomodate limited swelling which can occur at high pressures
- Large pressure differential over the seal. Common approaches to mitigate this involve
- Increasing the hardness of the seal in order to increase its extrusion resistance
- Pressure cycles. Common approaches to mitigate this involve
- Selection of materials which are more resistant to explosive decompression
- Dynamic application. Common approaches to mitigate this involve
- Increase the hardness of the seal
- Limit seal swell to 10 - 20%
- Poor packer seal seat design. Common approaches to mitigate this involve
- Seal design must allow for elastomeric swelling within 10 - 60% in oil and gas to prevent seal extrusion
- Seal design should take into account the installation requirements of the seal
- Penetration of hydrocarbons, Carbondioxide, and Hydrogen Sulphide into the elastomer. Common approaches to mitigate this involve
- Proper compatibility tests must be undergone prior to use
- Incompatibility with corrosion inhibitors and completion fluids. Common approaches to mitigate this involve
- Elastomeric resistance should be determined by testing prior to use
- Improper storage, handling, and installation. Common approaches to mitigate this involve
Other types of packer failure include the following 3 :
- Body collapse
- Packing-element system failure
- Pin collapse at the body/guide connection
- Body to Guide failure
- Anchor attachment failure
- Body lock ring system failure
- Bearing failure
Up next, we will examine flow control accessories.