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The CIRP (Completion, Insertion and Removal under Pressure) equipment is used to insert and retrieve long gun strings under wellhead pressure when the surface pressure control equipment, or lubricator, is shorter than the gun string. With the CIRP equipment, a long interval can be perforated under the optimum underbalance condition, and then the guns can be retrieved without exposing the formation to damaging kill fluids. Wells can also be reperforated without killing, minimizing production loss and formation damage. Multiple perforating runs can be completed without killing the well between runs.
A basic outline of the steps to be followed are listed below:
- The Initial gun is run into the lubricator down to the deployment BOP.
- The slick joint is positionedacross the no-go ram and the BOP no-go ram is closed.
- A pull test is performed to confirm the gun is positioned correctly.
- The gun is lowered back down onto the no-go.
- The BOP rack ram is closed which unlocks the CIRP connector.
- The upper part of the toolstring is picked up above the welbore isolation valves.
- The wellbore isolation valves are closed and pressure tested.
- The upper toolstring is removed from the lubricator and the next section of gun is installed into the lubricator.
- The lubricator is pressure tested and the wellbore isolation valves opened.
- The gun section is run into the lubricator until it engages with the gun section hanging in the deployment BOP.
- The BOP rack ram is opened which locks the CIRP connector, connecting the lower and upper toolstrings.
- A pull test is completed to confirm connection.
- The no-go ram is opened and the toolstring run down to the next slip joint.
This process is repeated until all toolstring sections have been connected together and the full gun length made up. The firing head and correlation tooling (on Coiled Tubing or Wireline) are connected to the gun string using the same method as described above and the gun run to depth and detonated as per operating procedures.
CIRP description and deployment stack diagram from Schlumberger website.
CIRP BOP diagram from Offshore magazine, March 2013.