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Subsea Separation presentation

  1. Subsea Separation: A New Frontier for the Chemical Engineer Sunday Kanshio AMIChemE Oil and Gas Engineering Centre, Cranfield University 15th April 2015
  2. Acknowledgement • Petroleum Technology Development Fund, Abuja, Nigeria • Prof Hoi Yeung- Oil and Gas Engineering Centre, Cranfield University • IChemE Milton Keynes Committee
  3. Presentation Outline • Demand for Oil and Gas • Subsea Field Development • Subsea Separation Systems • Academic Research and Findings • Conclusion
  4. Demand for Oil and Gas “Oil is expected to remain the No. 1 energy source and demand will increase by nearly 30 percent, driven by expanding needs for transportation and chemicals” ExxonMobil’s Outlook for Energy- A view to 2040; December 9, 2014 “Deepwater expenditure is expected to increase by 69%, compared to the preceding five-year period, totalling $210 billion from 2015 to 2019” Douglas-Westwood, London- March 9, 2015
  5. Subsea Production Systems • Flow assurance • Environment regulations • Maximising oil recovery • Low temperature • Water depth-Hydrostatic pressure • Long distance • Remoteness • Seabed topography Chemical Engineering Unit Operations Subsea Separation Where to go? Courtesy: Challenges Features of subsea oil and gas field
  6. Subsea Separation Subsea Separation Gas-Liquid Separation Oil-Water Separation Sand Removal • Hydrate prevention • Slug flow mitigation • Water re-injection • Topside debottlenecking • Erosion • Corrosion • Reduce backpressure on wells What is subsea separation all about? It’s more than phase separation!
  7. Subsea Separation Principles -Gravity HORIZONTAL SEPARATOR • Preferred for Oil-water separation • As Subsea Slug Catcher . Texaco developed Highlander using Subsea Slug Catcher • Required for slug flow mitigation • Water depth: 128 m • 13 km from existing platform • Low energy reservoir and low GOR • 35 million bbl of recoverable oil • Marginal field tieback to Tartan platform
  8. Subsea Separation- Techniques -Gravity HORIZONTAL SEPARATOR Good for Oil-water separation in shallow water Field application: Tordis field operated by Statoil Tordis Subsea Separation, Boosting and Injection Project • Water depth : 200 m • Mature field • 25 m tieback distance to Gullfaks C Platform • Water production: 70-80% • Sand production: 500 kg/day • Bulk water separation • Multiphase boosting • Water and sand injection into dedicated well
  9. Subsea Separation- Techniques -Gravity VERTICAL SEPARATOR • Preferred for gas-liquid separation • Easy sand removal • Provides adequate suction head Pazflor, Angola Courtesy of Total/FMC Example: Pazflor, Angola block 17 operated by Total • First tested at Cranfield University • Installed in 600 m-1200 m water depth • Heavy oil –Miocene reservoirs • Low reservoir pressure • Gas flow freely through 6-in flowline • Liquid boosted by Hybrid pump (18% GVF)
  10. Subsea Separation- Techniques -Caisson separation system Source: FMC Caisson separator system was used to develop Perdido and BC- 10 field. Shell as operator Perdido • Tieback to Spar • Heavy oil • Low reservoir pressure • Water depth : 2499 m • Gas flow free to host facility • ESP as boosting system BC-10 • Tieback to FPSO • Heavy oil • Low reservoir pressure • Water depth : 1499- 2000 m • Gas flow free to host facility • ESP as boosting system
  11. Heavy Outlet Inlet Compact Separation Systems -Centrifugal force Technology inspired by nature… Cyclonic separator utilizes the inertia of the incoming stream to generate high g-force to accomplish: ⁻ Coalescence ⁻ Phase separation Light Outlet Source : CALTEC
  12. Compact Separation Systems -Integrated systems HI-SEP I-SEP Source: FMC Marlim field operated by Petrobras was developed by integrated compact separation concept. • Marginal field in 900 m water depth • Heavy oil • Oil and gas comingled and flow to FPSO • Water re-injected into reservoir CALTEC integrated two compact separators Research by Cranfield University and CALTEC shows that this system can mitigate severe slugging in a way that does not reduce production rate unlike topside choking.
  13. Design and Operational Challenges -Can the Chemical Engineer help? Compact separation is the future of subsea separation but there are so many uncertainties concerning design and operation • Fundamental understanding of multiphase flow dynamics inside compact separators- Flow regimes, liquid holdup, phase distribution… • Narrow operating envelope of compact separators • Effect of upstream flow dynamics on separator performance • Knowing when the separator is performing poorly • Oil-water emulsion separation…Oil-in water measurement • Discharging produced water and sand at seabed • Predicting the performance of the separators over the field life • Design rules for compact subsea separatorsMy PhD is to help with the above challenges!
  14. Academic Work -Approach to Problem • Prototype Gas-Liquid Pipe Cyclonic (GLPC) separator fabricated, installed and tested. • Installed multiphase flow measurement sensors Trial GLPC Rig Standard GLPC Rig Tangential inlet Wire Mesh Sensor (WMS) ERT sensor
  15. Results Phase distribution prior to Liquid Carryover Phase distribution during Liquid Carryover ERT ERT WMS WMS
  16. Results and Findings Prior to liquid carryover During liquid carryover Findings • ERT, WMS and pressure transducers gave good information on what is going on inside the separator • Air-core has influence on phase separation • Mist, churn and annular flow regime can coexist in the gas discharge section of the separator under certain operating condition of the separator
  17. • Subsea separators does more than phase separation ; they solves flow assurance issues, extends the life of field, and enhances assets integrity • Phase separation using compact separators is the future of subsea separation • Chemical engineers should embrace subsea separation by bringing their understanding of unit operations to enhance the design of compact separators Conclusion
  18. Thanks for listening 07442978727