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Paraffin Blockage Remediation In A Flexible Flowline
Robert JamesProduction Engineer
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Outline
• Background • Remediation• Execution• Lessons Learned
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Background
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Medusa SS#5 Infrastructure
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Flow Assurance Challenges
• Uninsulated flowline• Pigging operations unavailable• Water injection tree
– Limited chemical injection points• Assumed similar fluid characteristics to offset well
– No down-hole samples obtained
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Medusa SS#5 HistoricalInitial Production
Snubbing Clean-out Operation
Paraffin Plug In Flowline
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Flowline Deposition
Bottom-hole Pressure
Boarding Pressure
Tubing Pressure
Subsea Flowline Pressure
Time Period Shown: 4 Years
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Remediation
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Remediation Options
Paraffin Deposition
Bullhead Solvent
Coil Tubing Cleanout
Snubbing Unit Cleanout
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Bullhead Operation
• Pumped 1000 gals of Xylene down flowline from platform• Impermeable paraffin blockage formed
Subsea Flowline Pressure
Boarding Pressure
Time Period Shown: 5 Months
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Remediation Options
Paraffin Deposition
Bullhead Solvent
Paraffin Blockage Formed
Coil Tubing Cleanout
Snubbing Unit Cleanout
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Coil Tubing
• Advantages– Circulation– Direct solvent
application to blockage• Disadvantages
– Potential for stuck work string
• Tractoring technology in horizontal section risky
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Remediation Options
Paraffin Deposition
Bullhead Solvent
Paraffin Blockage Formed
Coil Tubing Cleanout
High Potential For Stuck
Work String
Snubbing Unit Cleanout
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Snubbing Unit
• Advantages– Rotation capability– Circulation– Direct solvent
application to blockage– Proven industry method
• Risks– Flexible flowline integrity– Maneuverability of
curvature in flowline
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Flowline Curvature Risk - Mitigation
• Torque and drag modeling shows snubbing unit capable of operating through bend in flowline.
• Provided parameters while running in hole with work string.
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Solvent Selection• Solvent Selection:
– Diesel• HSE • Disposal• Cost Effective
– Effectiveness of diesel circulation in question at lower temperatures
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Mechanical Remediation
• Pipe in pipe modeling completed– Significant heat loss
expected • Removal of paraffin
using 3” O.D. brass nozzle
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Remediation Options
Paraffin Deposition
Bullhead Solvent
Paraffin Blockage Formed
Coil Tubing Cleanout
High Potential For Stuck Work
String
Snubbing Unit Cleanout
Execution
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Execution
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Operations SpreadSnubbing Unit
Circulation/Flowback
Heated Tanks
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Continuous Monitoring
• Snubbing parameters:– Pick Up and Slack Off Weights– Torque
• Diesel parameters:– Pour Point– Viscosity– Density
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Operational Results
Subsea Flowline Pressure
Tubing Pressure
Boarding Pressure
Time Period Shown: 3 Months
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Operational Results
• Well Test Recorded After Clean-Out• 1381 BOPD, 1223 MCFD, 213 BWPD
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Lessons Learned
• Job Execution – Accurate modeling– Multiple remediation options– Real-time monitoring
• Field Development– Accurate data acquisition– Appropriate infrastructure
• Insulation Requirements• Chemical application
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Acknowledgements
• David Mayfield• Alyce Anfang
Contact Information
• Robert James• Murphy Oil Corporation• [email protected]• 832-319-5443
Questions?
