HOUSTON – DNV GL has issued a new, globally applicable recommended practice (RP) on risk-based abandonment of offshore wells, which it says represents the highest cost within field decommissioning for operating companies and national authorities.
DNV GL said that when applied in combination with optimized project execution and new technology, the RP could potentially reduce P&A costs by 30-50%.
The framework outlined in the RP provides the possibility for individualized, fit-for purpose well abandonment designs, which DNV GL believes differs from what it termed the “prescriptive methodology” available in the industry today.
Well abandonment is driven by economic decisions, when the production of an oil or gas reservoir ceases or is no longer profitable. Authorities require that well operators perform safe and environmentally friendly operations by establishing a permanent barrier to prevent release of hydrocarbons to the surface, it explained.
Per Jahre-Nilsen, business development leader, Drilling & Well, DNV GL – Oil & Gas, said: “The costs related to well P&A are enormous. Using current practices, there will be a global fleet of dozens of full-time drilling rigs needed to perform P&A for generations to come. We believe the time has come to tackle this issue head on by assisting regulators and the industry to establish a new methodology for dealing with the decommissioning of wells.
“By using this method, hazardous wells will get the attention they deserve, and benign wells will avoid excessive rig-time and expenditure. We’re looking at potential cost savings of more than $32 billion on the Norwegian continental shelf alone, and even more globally.”
The DNVGL-RP-E103 “Risk based abandonment of offshore wells” is based on case studies performed by DNV GL in projects dating back to 2011. A process is defined where the key stages in the risk-based methodology are assessing the well barrier failure modes, well flow potential, valued ecosystem and safety components, dispersion modeling and impact analysis. These steps are designed to result in a consistent method to be applied when assessing risk of the offshore well abandonment designs. The RP methodology provides assurance that selected well abandonment designs are robust, environmentally friendly and economically advantageous.
Elisabeth Tørstad, CEO of DNV GL - Oil & Gas, said: “DNV GL helps the industry to understand and manage the risks of their operations. Risk-based approaches are widely used in all other offshore disciplines, ensuring appropriate long-term environmental protection and also representing the most efficient method to ensure safety. It is time to apply these principles to P&A.”
Practice also differs from country to country, DNV GL said. The new RP uses risk-based approach methodology in which both environmental and safety risk aspects are key factors. Through the development of the RP, DNV GL worked with international oil and gas operators to establish an initial set of risk acceptance criteria and cross-checked these using case studies.
DNV GL is exhibiting at booth #5155.