eelReel Blockage Remediation For GOM Deepwater Flowline Decommissioning

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A GoM operator of a 6-inch subsea oil production flowline experienced severe paraffin blockage. The said deposition prevented a successful hydrocarbon de-inventory procedure in order to properly abandon the asset per compliance regulations. Due to insufficient pump rates, the operator faced expensive, complex subsea intervention tasks based upon routine flow assurance methods typically applied in decommissioning scopes of work.

Specifications

• OD: 6.625 inch

• ID: 5.5 inch

• Length: 17,350 feet

Scope of Work

Interface with conventional Coiled Tubing and solids handling systems to mechanically remediate a deepwater flowline.

Challenges

• Access the flowline adjacent to platform PLET.

• Utilize an intervention vessel in deepwater for standalone operations.

• Remove all organic and inorganic deposition with patented mechanical jetting and scrapping action.

• Displace the fluid media with seawater for permanent abandonment by swabbing flowline when POOH.

Plan of Execution

1. Project Pre-planning

   1. Assessment and evaluation of previous work performed on the flowline provided sound engineering procedure.

   2. Fluid handling and chemical equipment SME provided valuable risk management and hazard identification.

2. Project Preparation and Setup

   1. Aligned coiled tubing (CT) system and fluids/solids handling systems for deployment into the flowline from on an intervention vessel.

   2. SME with flowline infrastructure enabled identification of proper tie-in connections and associated equipment for flowline alignment. Flowline was disconnected at the platform PLET and lifted alongside the intervention vessel.

3. Project Execution

   1. SIMOPS alongside intervention vessel and coil tubing contractor.

   2. SME with chemical engineering diagnostics provided proper application of fluid cleaning systems.

   3. Cantilever system enabled the flowline to be lifted from the sea floor to the intervention vessel for tool accessibility and launch.

Technical Achievements & Benefits

• Executed 24-Hour SIMOPS schedule.

• Flowline abandonment procedure approved by regulator.

• Deep clean of flowline with all hydrocarbon inventory removed in one single and continuous pass.

• Flowline cleanliness verified thru oil and gas analyzers and successful sheen test.

• Project completed with zero incidents, no environmental impact, and within budget.

• Saved the operator significant costs that were not originally budgeted for this decommissioning scope.

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