Author

Jan Bogø Pedersen, Lead Wells Engineer

The well engineering team and I are presently working our way through the plug and abandonment (P&A) design process on an exciting project – the permanent plugging and abandonment of Tullow Oil’s Banda and Tiof fields offshore Mauritania. We were awarded the project in February, and planning and engineering began immediately. Now we are focused on delivering for our customer and ensuring we maximise safety, efficiency and cost effectiveness along the way.

Press Release: Maersk Decom wins complete plugging and abandonment of Tullow Oil’s Banda and Tiof fields

The project consists of seven exploration and appraisal wells drilled between 2002 and 2008 which are to be permanently plugged and abandoned. Despite challenges presented by the COVID-19 outbreak, we have been able to carry out the engineering work interactively from our home offices and have progressed without delays.

The well engineering team at Maersk Decom brings together a total of 60+ years of experience within wells disciplines – from drilling and operations to production and well equipment engineering. We have all worked for operators across many geographies, mainly around the North Sea, drilling new wells, repairing wells and plugging and abandoning wells.

Having spent 15 years offshore as an Engineer and Company Supervisor, and an equal amount of time onshore as a Superintendent for drilling, completion, workovers and P&A operations, I believe the most important focus areas to optimise the P&A programme are staying up-to-date on industry best practices, being observant to any possibility of introducing innovations and securing reliable well data.

Learning from and refining industry best practices

All Maersk Decom Well Engineers are dedicated solely to plug and abandonment. This means we are constantly learning and refreshing our knowledge on this part of the well life cycle and can ensure we bring in leading technologies and methodologies. Combining diverse experience with a focus on P&A, it is possible to develop the right P&A programme – minimising costs without compromising safety.

Reliable data is key

Being able to employ industry relevant innovations and best practices depends on having the most reliable facts and most recent data available. With a complete, reliable overview, we have the best chance of catching any potential challenges from the start. When it comes to older and temporarily suspended exploration wells, data may be filed and not looked at for a long time. Additional challenges may be presented in cases where field operatorship changes. Therefore, the detailed data review is the most critical step in the well engineering process.

Well engineering for the Banda and Tiof fields to date

Engineering work commenced with a thorough review of the data available on the wells, and summarising this information into a basis of design document. Once the document was approved by the customer, engineering work continued to creating the P&A well design with descriptions, calculations and schematics for the wells, outlining placement of the permanent cement barriers. The well design has been based on the Norwegian standard: NORSOK D-010.

Sometimes, during this phase, we need to collect even more data than is initially supplied in order to optimise the design. In this case, we found that additional information about the geology and petrophysics of the wells would be valuable. Currently, we are collaborating closely with a third party subsurface contractor to perform a review.

Developing the P&A programme

When the P&A well design is complete, a technical peer review will be held with the customer, the subsurface contractor and the well examiner from the local authority. Once the well design for all seven wells have passed this review, the documentation will be incorporated into a P&A programme and further developed to include descriptions of how the work will be performed in practice, as well as an updated cost estimate.

Moving towards offshore execution

Soon, the P&A programme will need approval from the well examiner and local authority. Once received, our engineering team will proceed with planning and preparing for execution, as well as assisting our Procurement & Contracts Manager with tendering for the well services required.

A key benefit of delivering the entire scope from one integrated project team is that we are able to reduce interfaces for our customer so they only need one point of contact. This also allows us to supply a cost estimate up front for the entire project, as we will see it all the way through from the permanent plug and abandonment to the end of well report.

Since we are providing a solution that bundles project management, engineering and planning with the execution of plug and abandonment as well as the removal and disposal of subsea equipment, several other Maersk Decom functions have also been involved in the project so far – such as the Project Manager, Recycling & Waste Management Engineer and Facilities & Removal Lead. Together, we aim to deliver safe, reliable and efficient decommissioning solutions with a focus on innovative and industry leading practices.

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