Salt: ESCO – Frisia well BAS-3 plug & abandonment 2012

Salt producing well BAS-3 abandonment

Start execution: June 20th 2014
End execution: September 6th 2014

Result: Successful permanent abandonment of salt production cavern

Depth (AH): 4444m
Depth (TVD): 2876m

Project Summary

Client: ESCO - Frisia Zout B.V.
Location: Pietersbierum
Wells: BAS-3
Start Execution: June 20th 2014
End Execution: September 6th 2014
Target: Final abandonment of a high-pressure salt production cavern.
Result: Successful permanent abandonment of salt production cavern.
Depths (AH): 4444m
Depths (TVD): 2876m
Role of WEP: Well Engineering Partners provided project planning, tendering engineering, coordination, management and supervision for the project while other companies provided materials and services.
Challenges: High torque due to S-shape well and use of high friction fluid. Challenging downhole conditions, limited full bore access.

Project Description

Following the temporary plugging of the well with snubbing operations in end 2013 the Deutag T207 (350t) drilling rig was used to permanently abandon the existing salt cavern.

To place the final abandonment plug the inside of the well was successfully dressed down to depth. Following this operations attempts were made to retrieve the 11-3/4” casing completely; after retrieval of the upper half of the casing, it was however found be severely stuck. To complete the abandonment a section was then milled in the 11-3/4”casing, after which a cement plug was placed.

Throughout this phase of the project, the operating torque was high. This was caused by the S-shape profile of the well, combined with the high friction water-based milling fluid, which was required for hole cleaning with metal cuttings. Detailed BHA modeling for side loads and resulting torque and drag was therefore used actively with good results in order to optimize the milling operations.