IOGP Well Control Incident Lesson Sharing
<<< Back to Results

Printable version

Confirm that all equipment in the well control circulating path is rated for the application

The tubing was cemented in rotation using a casing drive system (integrated elevator/circulation device connected to top drive). The program called for a slurry displacement with an underbalance brine 1.02SG in order to leave the tubing full of clean fluid for subsequent operations.

The plug was bumped. During the tubing P-test at 7300psi - pressure dropped to 5300psi - 6 bbls were bled off to check floats - no success. Observed pressure build-up indicating link to reservoir (+/- 40psi/hour).

Unfortunately the surface rig-up (casing drive system) was only 5K working pressure (WP) and did not allow slickline access due to a restricted Internal Diameter.

What Went Wrong?:

The casing drive system was not identified as being part of the secondary barrier system at the end of the displacement.

Packing elements of the Casing Drive System were not qualified - only 5K WP for 7.5K MEWHP.

Mechanical barrier failure - shoe track integrity.

Displacement with an underbalance fluid disabled the primary barrier (hydrostatic fluid).

Corrective Actions and Recommendations:

An operational risk assessment of the operation must be performed and "What If" situations evaluated (failure of shoetrack integrity).

Revision of the cement job procedure and landing string design - must incorporate a surface safety valve and possibility to run through a contingent of mechanical barriers.

All the equipment being part of the barriers (primary and secondary) must be qualified to the MEWHP.

Figure 1: Surface set-up

Schematic of the pumping set-up with 5K packing elements (for a 7300psi MEWHP)

safety alert number: 303
IOGP Well Control Incident Lesson Sharing


Whilst every effort has been made to ensure the accuracy of the information contained in this publication, neither the IOGP nor any of its members past present or future warrants its accuracy or will, regardless of its or their negligence, assume liability for any foreseeable or unforeseeable use made thereof, which liability is hereby excluded. Consequently, such use is at the recipient's own risk on the basis that any use by the recipient constitutes agreement to the terms of this disclaimer. The recipient is obliged to inform any subsequent recipient of such terms.
This document may provide guidance supplemental to the requirements of local legislation. Nothing herein, however, is intended to replace, amend, supersede or otherwise depart from such requirements. In the event of any conflict or contradiction between the provisions of this document and local legislation, applicable laws shall prevail.

City Tower, 40 Basinghall Street
Level 14
London, London EC2V 5DE
United Kingdom