SPREX® and SPREX®CO2 are processes developed for bulk acid gas removal from highly sour gas. SPREX® and SPREX®CO2 offer economic alternatives for the development of highly sour gas reserves with acid gas reinjection which allows CAPEX and energy consumption reduction and limits sulphur production. SPREX® has been developed to meet the challenges of the development of very sour (>10% acid gases) natural gases.

Process Principle

Highly sour gases are splitted in a cryogenic distillation, producing partially sweetened gas at the overhead and liquid acid gas mixture at the bottom, which is suitable for reinjection.

Process Scheme



  • H2S bulk removal from raw gas with over 25% H2S, with reinjection of liquid H2S
  • No upstream sour gas dehydration needed


  • CO2 bulk removal from raw gas with more than 35 - 40%  CO2, with reinjection of liquid  CO2
  • Upstream gas dehydration required
  • 18 - 25%  CO2 in outlet gas, @ -50 / -55°C in reflux drum
  • Energy saving by 50% and CAPEX savings by 20% vs. 2 stages membrane (@ 70%  CO2 in sour gas)
  • 8 - 12% H2S in outlet gas to amine unit, @ -30 to -40°C in reflux drum
  • Energy saving “SPREX ® + Amines” by 35% versus “Amines” process (@ 35% H2S in sour gas)

Key Benefits

  • Bulk H2S or  CO2 removal from highly sour gas by high pressure cryogenic distillation
  • Conventional distillation column with no hydrate or solid product formation
  • Separated acid gases are recovered liquid at high pressure and easily pumped back into reservoir
  • Final sweetening of partially treated gas may be done with a conventional amine unit
  • Economic alternatives for the development of highly sour gas reserves with acid gas reinjection
    • Reduced capital cost and energy consumption versus conventional alternatives
    • Limits sulphur production and/or  CO2 release to atmosphere
  • Proprietary solid/liquid/vapor thermodynamic model, validated through lab data and demonstration plant operation
  • Process design and robustness of operation validated through demonstration plant operation for more than 18 months

SPREX® is a joint development between IFP Energies nouvelles, TOTAL and PROSERNAT