Subsea Seperation Development

Subsea processing (SSP) can be defined as any handling and treatment of the produced fluids for mitigating flow assurance issues prior to reaching the platform or onshore. This includes:

The benefits of introducing subsea processing in a field development could be:

  • Reduced total CAPEX, by reducing the topside processing and/or pipeline CAPEX;
  • Accelerated and/or increased production and/or recovery;
  • Enabling marginal field developments, especially fields at deepwater/ultra-deepwater depths and with long tie-backs;
  • Extended production from existing fields;
  • Enabling tie-in of satellite developments into existing infrastructure by removing fluid;
  • Handling constraints;
  • Improved flow management;
  • Reduced impact on the environment.

Subsea boosting, as explained in an earlier section, is one means of increasing the energy of the system. Subsea separation can be based either on two- or three-phase separation:

  • Two-phase separators are used for separation of any gas–liquid system such as gas–oil, gas–water, and gas–condensate systems.
  • Three-phase separators are used to separate the gas from liquid phase and water from oil.

The technology and products required for subsea boosting and water removal are available and in operation, while three-phase separation and subsea gas compression still require some qualification before being put into operation. Thus, a three-phase separator is useful for the crude consisting of all three phases, namely, oil, water, and gas, whereas a two-phase separator is used for the system consisting of two phases such as gas–oil, gas–water, or gas condensate. Further, subsea separation could have a positive effect on flow assurance, including the risk related to hydrate formation and internal corrosion protection derived from the presence of the produced water in combination with gas. As opposed to the traditional methods of processing reservoir fluids at a process station, subsea processing holds great promise in that all of the processing to the point where the product is final salable crude is done at the seabed itself. This offers cost benefits and also improves recovery factors from the reservoir. Other advantages include a lesser susceptibility to hydrate formation and lower operating expenditures.


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[2] M. Faulk, FMC ManTIS (Manifolds & Tie-in Systems), SUT Subsea Awareness Course, Houston, 2008.

[3] R. Eriksen, et al., Performance Evaluation of Ormen Lange Subsea Compression Concepts, Offshore, May 2006.

[4] CITEPH, Long Tie-Back Development, Saipem, 2008.

[5] R. Sturgis, Floating Production System Review, SUT Subsea Awareness Course, Houston, 2008.

[6] Y. Tang, R. Blais, Z. Schmidt, Transient Dynamic Characteristics of Gas-lift unloading Process, SPE 38814, 1997.

[7] DEEPSTAR, The State of Art of Subsea Processing, Part A, Stress Engineering Services (2003).

[8] P. Lawson, I. Martinez, K. Shirley, Improving Deepwater Production through Subsea ESP Booster Systems, inDepth, The Baker Hughes Technology Magazine, vol. 13 (No 1) (2004).

[9] G. Mogseth, M. Stinessen, Subsea Processing as Field Development Enabler, FMC, Kongsberg Subsea, Deep Offshore Technology Conference and Exhibition, New Orleans, 2004.

[10] S.L. Scott, D. Devegowda, A.M. Martin, Assessment of Subsea Production & Well Systems, Department of Petroleum Engineering, Texas A&M University, Project 424 of MMS, 2004.

[11] International Standards Organization, Petroleum and Natural Gas Industries-Design and Operation of the Subsea Production Systems, Part 1: General Requirements and Recommendations, ISO 13628-1, 2005.

[12] O. Jahnsen, G. Homstvedt, G.I. Olsen, Deepwater Multiphase Pumping System, DOT International Conference & Exhibition, Parc Chanot, France, 2003.