Nick J Gill
Devex Conference 2016
Aberdeen, UK
ConocoPhillips UK Decommissioning:
June 16, 2016
The Challenge and the Process
Decommissioning at ConocoPhillips
June 16, 20162
Group formed in May 2013:
• 28 Southern North Sea wells Plugged and Abandoned
• Redundant equipment removed at Theddlethorpe Gas Terminal
• MacCulloch FPSO decommissioned and removed from station
• Viking satellites transfer to cold suspension currently in progress
1. Plug & Abandon Wells (P&A)
2. Final Clean & Disconnect
3. Dismantle & Dispose
4. Surveillance & Monitoring
STAGES OF DECOMMISSIONING:
Viking Complex
0
200
400
600
800
Cu
mu
lati
ve T
ime
(d
ays)
Well Plug and Abandonment example: Viking Area
June 16, 20163
VIKING AREA P&A:
• Wells dating back to 1969
• Campaign commenced June 2014
• Ensco 92 jack-up rig satellite campaign
• 28 wells completed to date
RIG PERFORMANCE CURVE:
PLANNED
ACTUAL
Learning Curve takes effect
KEY LESSONS LEARNED
• Offshore: “multi-skill”, retain same team, build on the learning curve
• Offshore: Always have a Plan B (and Plan C)
• Onshore: Ensure a diverse engineering team
• Cost reduction: Look for best value, not necessarily cheapest price
Final Clean and Disconnect example: MacCulloch FPSO
June 16, 20164
105km of pipelines &umbilicals to clean <30ppm
115 subsea disconnects,
+90% to complete by
divers
FPSO on station since
1998
+20 topsides systems to flush and
de-gas
• Final production from the facility in May 2015
• 4 month programme of final clean and disconnect prior to FPSO removal
• Collaborative effort between 2 owners, 3 major sub contractors and downstream operator
Final Clean and Disconnect example: MacCulloch FPSO
June 16, 20165
PIPELINE CLEANING METHODOLOGIES:
Cleaning programme designed to remove hydrocarbon in stages:
1. Gas removal
2. Liquid removal
3. Solids/ immobile hydrocarbon removal
No well disposal – gas lift system used as ‘loop’
Both foam and hard-bodied pigs utilised
Solvents used in oil export system to dissolve wax
Gel pigs used in non-piggable flowlines
KEY LESSONS LEARNED:
Thorough engineering process/ procedure review
Overdesign reduces risk of operational delay (e.g. staged cleaning)
Physical barrier vs turbulent flow
Pig-trials (test and in-situ)
Knowledge of systems
Chemicals and permitting
Agree and document sampling regime
Removal & Disposal
June 16, 20166
INFRASTRUCTURE REMOVED TO DATE:
MacCulloch Field:
• 4km of flexible risers (steel and composite plastics)
• 2 x 100Te mid-water arch structures
Theddlethorpe Gas Terminal:
• 2 x 30Te redundant methanol stills
• 1 x 50Te redundant heat exchanger
KEY LESSONS LEARNED
• Ensure robust philosophy for handling removed material; the “Disposal Hopper”
• Use of photographic survey software (e.g. R2S) will reduce need for offshore surveys
• Ensure all activities are permitted with the appropriate regulatory body
• Contract structure – ensure maximum flexibility but minimise risk (separate or combined removal and disposal contracts?)
• Trial cuts onshore where possible
Summary
June 16, 20167
Final Clean and
Disconnect
Well Plug & Abandon
Remove and
Dispose
Post Removal
Ensure diverse engineering team
Focus on value over price in engineering/ materials
Maintain consistency of offshore crews
Over-engineering reduces risk of operational delay
Multiple checks and procedural reviews
Know the details of the systems
Flexibility in contract structure
Detailed surveys ahead of operations
Disposal philosophy agreed to minimise waste
Stakeholder engagement is crucial
Monitoring regime