THE CHALLENGE
As part of a slot recovery and redrill operation on a North Sea field, the operator needed a 9 7/8-in., 62.8 lb/ft, P110, VAM SLIJ-II (8.5-in. special drift) full casing string to 2,678 m MDBRT.
Inclination ranged from 0° to a maximum of 72°. The centralizers needed to pass through 13 3/8-in., 72 lb/ft, L80 New VAM existing casing to 600 m MDBRT, and then through an 11 3/4-in., 60 lb/ft, P110, TSH W523 liner (10.625-in. special drift) to the 11 3/4-in. shoe at 1,281 m MDBRT.
The operator then needed to continue through the open hole to TD.
THE SOLUTION
The drilling engineer ran a total of 140 UROS-CT centralizers (9 7/8-in. × 11 3/4-in.) in combination with Protech bonded stop collars with 8 mm blades, using one or two centralizers per joint.
THE RESULT
No issues were encountered during onshore installation, and the casing was successfully run to 2,678 m MDBRT. The UROS-CT centralizers passed through the existing casing and 10.625-in. special-drift liner before continuing into open hole, with inclination reaching 72°.
Actual running forces matched the torque-and-drag model predictions, validating the centralizer selection and placement strategy. The cement job proceeded as planned and met all annular isolation objectives.
The casing was successfully run through a salt diapir consisting predominantly of halite, with polyhalite stringers and an anhydrite caprock at TD.
