Offshore P&A – HWU and Liftboat - Balance Point Control

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.