EelReel Deepwater Riser Blockage Remediation on TLP


An operator of a mini-TLP experienced flow assurance problems in a subsea oil production flowline system. Operator knowledge and production history identified the issue as a paraffin blockage. Unsure of the blockage location and remediation method, several failed attempts at pressure cycling from the subsea and platform sides resulted in a mechanical remediation need.

Challenges

  • Determine the blockage location.

  • Access the SCR via temporary riser and hull pipework.

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

  • Multiple internal diameter changes.

Scope of Work

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

Plan of Execution

  1. Project Pre-planning

    1. In conjunction with the GATE Energy flow assurance team, the production system was modeled and a range of remediation options were determined.

    2. Project-specific tool design was required based on several internal diameter changes between the topside and subsea system. Upon a successful build and test method, the project team received Operator approval for scope readiness.

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

  2. Project Preparation and Setup

    1. Identified an approved method for blockage location using state-of-art diagnostics system.

    2. Arranged coiled tubing (CT) system, fluids/solids handling systems, heated diesel system, and solvent surfactant chemistry for scope alignment.

    3. SME with flowline infrastructure enabled identification of proper tie-in connections and associated equipment for flowline alignment.

  3. Project Execution

    1. Determined blockage location as being approximately 4,500’ in the SCR.

    2. SIMOPS alongside CT contractor and platform personnel.

    3. CT and eelReel tool were deployed into the SCR via temporary riser.

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

Technical Achievements & Benefits

  • Executed 24-Hour SIMOPS schedule. Entire SCR remediation clean out performed within 36 hours after deployment. Project completed with zero incidents, no environmental impact, within budget, and under schedule.

  • Accurate blockage location acquired. 3-5 bbls. of paraffin removed.

  • Fast-track modeling of operator system determined an approved remediation strategy. Successfully designed, built, and tested a project-specific tool that could navigate the ID changes of the operator’s system. Tool traveled more than 4,500’ and navigated multiple bends and internal diameter changes.

  • Innovative layout design accommodated equipment spread within a limited available working space while interfacing with the operator’s system. POOH and fast rig down enabled quick production commencement.

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