Notes on Lima Platform Decommissioning Presentation

Overview

• Lima Platform: Last remaining offshore rig in one of Britain’s gas fields.
  • Built of 2,500 tons of steel and 15 miles of pipework.
  • Supplied gas to 5 million homes for almost 40 years.
  • Scheduled for demolition due to depleted gas reserves.
  • Decommissioning project estimated to cost £1.5 billion and take approximately 9 months.

Engineering Challenges

• Demolition Techniques:

  • Diamond-coated wires and gas axes used to cut through thick steel.
  • Emotional aspect for engineers who constructed it.
  • Requires unique technical skills and experience.

• Decommissioning Process:

  • Involves dismantling every part of Lima, uncovering its internal mechanisms.
  • Engineers include Rob Bell (mechanical engineer) and Tom Wigglesworth (electrical engineer).

Historical Context

• Discovery of Gas: Lima was at the heart of the indefatigable gas field discovered in the 1960s.
• Construction Beginnings: Engineers recall the early days and challenges faced during construction.
• Veteran Engineers:
  • Austin Hand, Bill Lindsay, Mick Needham share experiences from the platform’s construction.

Decommissioning Steps

1. Plugging Wells:

   • Lima had six wells drilled two miles under the sea, which need to be sealed with concrete.
   • Conductors cut for removal.

2. Removing the Platform:

   • Topside (1,350 tons) removed using crane after ensuring structural integrity.
   • Legs (2,500 tons) have to be dismantled, embedded deep in the seabed.

3. Cutting Techniques:

   • Use of advanced cutting solutions like diamond wire cutters and high-pressure water cutters to sever steel.
   • The jacket legs need to be cut off three meters below the seabed to avoid leaving traces.

Geological Insights

• Gas Formation:

  • Understanding of gas pockets in porous rock formations.
  • Gas formed from organic matter, requiring specific geological conditions for extraction.

• Impact of Clean Sea Policy:

  • Initiated after Greenpeace protests against dumping in the ocean, leading to stricter decommissioning regulations.
  • Estimated cost of decommissioning in the UK is $100 billion.

Final Demolition and Recycling

• Recycling Process:

  • 99% of materials from Lima will be recycled, including wood, steel, and algae.
  • Steel from Lima is repurposed for building new platforms, showcasing sustainability in the industry.

• Economic Factors:

  • Recycling expected to generate significant revenue while considering safety and environmental impacts.

Conclusion

• Legacy of Lima:
  • Represents an era of North Sea oil and gas exploration.
  • Engineers reflect on their emotional connections to the platform and the impact of its removal.
  • Removal costs over £200 million and involved extensive labor hours.
  • Transition to new technologies in offshore oil and gas extraction continues.