MILLING OF HARD SCALE OFFSHORE NORWAY

Well Cutter for medchanical solutions

Background

Offshore Norway, a downhole safety valve (DHSV) had locked in the open position with no access from surface due to scale. The client had attempted broaching for two weeks, which had opened up the well to 4.6”. However, this method was too time consuming because the scale was of a very hard consistency.

OPERATION

Due to pressing time issues and scheduled rig maintenance, they turned to Welltec’s capabilities to deliver an e-line, scale removal solution. Welltec® quickly mobilized a Well Tractor® and Well Miller® along with a complement of various milling bits.

After four runs of milling this hard scale, the Well Miller had cleared the scale down to the DHSV, opening the well up to an ID of 4.7”. A CCL was run and confirmed the depths.

At this point an attempt was made to pull the DHSV but the fishing neck was unable to be latched. The Well Miller was called into action again and using a brush bit was able to clean the scale around the DHSV, allowing it to be retrieved successfully.

ACHIEVEMENTS

After Welltec had removed the scale, the client was able to pull the DHSV and replace it with a new one. In total, Welltec had an operational time of less than 7 days with an effective milling time of 22 hours with Well Tractor and Well Miller versus the two weeks for broaching (without reaching target).

Client quote

“I would like to thank you and your team for the excellent effort so far. Although we have not yet retrieved the DHSV, the tractor/milling has performed beyond what I anticipated. Welltec mobilized for this job with very little advance notice and the support from the onshore staff in Tananger and Bergen has been first class.

The equipment and contingency accessory items were called into action and performed well. You have set the standard for the future milling operations and expectations.”

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Client quote, onshore supervisor

“The equipment and contingency accessory items were called into action and performed well. You have set the standard for the future milling operations and expectations.”