Offshore P&A – HWU and Liftboat

Optimize cost/quality

Background

The platform is located in the German part of the North Sea in shallow water. The platform supports a single 3200m deep gas production well which was drilled and completed in 1991.

Objective

The objective was to Plug & Abandon this single gas production well and to remove the surface casing, conductor and wellhead.

Execution

  • HWU in combination with a lift boat was selected for this P&A project because of the best cost/quality ratio for this well.
  • Engineering was performed to ensure rig-up stability and to enhance operational efficiency and quality.
  • HWU and BOP’s were rigged up directly on top of the wellhead and an access platform was made for easy and safe access.
  • The completion was removed and a CBL was conducted to verify casing cement.
  • Cements plug were set on top of mechanical bridge plugs.
  • 7-5/8” production casing was cut using a mechanical rotational cutter and retrieved by using a casing spear.
  • 9-5/8” casing was cut and retrieved by using an explosive cutter and spear.
  • HWU was rigged down.
  • 13-3/8” casing was retrieved with a small Jacking system and 30” casing was retrieved using the platform crane.

Results

  • Good engineering and project planning resulted in a remarkable operational efficiency.
  • The well was successfully plugged. All cement plugs were positively tested during the first test.
  • The HWU operation was completed in 24 days (Incl; NPT, waiting on -weather, -parts and -decisions, maintenance, Rig Up/Down time, etc).
  • Zero incidents and accidents.