DNV—GL — RISK—BASED ABANDONMENT OF OFFSHORE WELLS

The content of this recommended practice is dealing with the risk based abandonment of the wells drilled offshore. The offshore wells being drilled commonly need permanent abandonment to get the subsurface pressure duly controlled and also to prevent the pore fluids from free flowing to the sea floor. The purpose of the so-called P&A standing for the plug and abandonment of the offshore wells is protection of the environment; of course, all safety standards are to be maintained.

The wells to plug and abandon offshore vary. Some of them require less complex plug and abandonment operations - they can normally be plugged using the simple P&A solution or existing drilling equipment of the platform. The other wells will require a rig capable of handling heavier P&A operations that, in turn, may require casing, tubing, milling, cement repairs etc.

The older wells sometimes lack basic documentation and paperwork required for the plug and abandonment - this is especially a case if this well has changed the owner. The main objective of this publication is to provide industry with the effective risk-based framework to be applied to the design of the well abandonment and is therefore a needful one for the offshore workers.