Schlumberger

Case Study: Fishing Operation Enables Operator to Reenter Sidetracked Well in Germany

Retrieval of whipstock and anchor allows for access to the original wellbore

Challenge: Retrieve a previously set whipstock system and gain access to original well that was sidetracked and then plugged because of wellbore instability.

Solution: Plan the fishing operation in two phases. First, clean the cement around the top of the whipstock and pull the whipstock slide using a retrieval hook. During the second phase, disengage and retrieve the packer anchor.

Result:

  • Successfully retrieved the whipstock and permanent packer.
  • Reentered the original wellbore in 9 5⁄8-in casing.

Retrieve whipstock and permanent packer from a plugged well

An opertor wanted to reenter the main wellbore of a well in Germany, which was previously sidetracked and then plugged because of wellbore instability issues. The whipstock and permanent packer anchor used in the earlier operation were covered with cement during plugging. To reenter the borehole, the operator needed to fish the whipstock and packer out of the well. The packer, which was designed to stay in the hole permanently, added to the challenging operation.

Perform a two-phase fishing operation

It was expected that the whipstock slide and anchor would separate during fishing, so a two-phase plan was developed. The whipstock was set at 646 m inside the 9 5/8-in casing with 8.679-in ID. In the first phase, an 8 1/2-in washover assembly and a jetting tool were used to clean the cement over the whipstock from 645 m to 649 m. Then a whipstock retrieval hook was run to 646 m to free and recover the whipstock slide. As expected, the packer anchor sheared from the whipstock slide and remained in place.

During the second phase of the operation, the permanent packer was disengaged from the casing using an 81/8-in overshot assembly at 652 m. Then it was pulled to surface, and a reverse circulation junk basket was run in hole to retrieve any packer slips that had washed away from the body.

Reenter the plugged well

The fishing operation was successful, retrieving both the whipstock and permanent packer. With access to the original wellbore regained, it enabled the operator to reenter the well.


Download: Retrieval of Whipstock and Anchor Allows for Access to the Original Wellbore (0.17 MB PDF)

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