How simulation can help in oil field de-commissioning

As more governments mandate that outdated offshore installations be removed in accordance with strict regulations, decommissioning has become an increasingly important pillar of the oil and gas ecosystem. But it’s a time-consuming and expensive one.
According to the North Sea Transition Authority Decommissioning Cost and Performance Report, the North Sea oil and gas industry spent £1.6 billion decommissioning redundant wells and infrastructure last year – higher than any of the previous 5 years. And the decommissioning of Dutch oil and gas infrastructure is currently estimated to cost €6.7 billion, 55% of which relates to offshore operations.

When you’re under this kind of cost, regulatory and time pressure, how to optimise well decommissioning?

In addition to traditional logistics challenges, the decommissioning industry has to account for weather conditions, vessel delays and other issues relating to offshore infrastructure, such as available deck space and the weather sensitivity of cranes and ships. Traditional scheduling tools and static analyses can’t account for the complexity and variability of offshore logistics. Although those tools have their place in the planning process, they end up oversimplifying situations – so you don’t end up accounting for the nuances of offshore operating conditions and infrastructure.

Predictive simulation helps you make more informed planning and optimisation decisions

It allows you to understand, visualise and experiment with real-world operational characteristics in a virtual environment. With predictive simulation, you can model assets and dynamic processes, so you can analyse ‘what-if’ scenarios involving complicated variables – and in a risk-free way. Twinn Logistics Simulator simplifies this process for well decommissioning, giving you configurable, rapidly deployable modules covering the entire value chain – from long-term horizon planning to verification assessments and operational optimisation. It helps streamline the decommissioning process by helping you:

• Plan each project phase, from start to the eventual decommissioning of the extraction wells
• Model the whole supply chain across all decommissioning phases
• Optimise the fleet to deliver heavy equipment to shore and prevent vessels from waiting
• Meet project deadlines by pre-testing the robustness of logistics plans

Oil & gas operator speeds up North Sea decommissioning: simulation in practice

As part of the decommissioning field project in the North Sea, one major oil and gas operator was planning plug and abandonment (P&A) activities for over 25 wells at the platform. Costs were linked to the duration of activities, which needed to be as efficient as possible.

However, operator faced several constraints, including limited deck space for storing items and an older, less reliable and weather-sensitive crane. Customer wanted to speed up P&A activities (and therefore reduce costs) despite those constraints, and turned to simulation to find the best way to achieve that.

Using Twinn Logistics Simulator, we worked with operator to analyse the end-to-end P&A process, identifying bottlenecks and comparing the risks and rewards of various optimisation options. We tested several scenarios to assess their effect on P&A timescales:

• Replacing an existing crane with one that had higher reliability and capacity
• Increasing desk space by removing facilities
• Increasing or changing supply vessel visits and other ship visits
• Changing the well decommissioning schedule

Thanks to the simulation, oil and gas operator had robust evidence for deciding which improvements to pursue. And our customer was able to plan and execute P&A work in the most effective way, making these operations faster, more cost-effective and sustainable.