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CO2 Injection Workover Assessment, Australia

Zenith Energy Australia was engaged to perform a conceptual workover assessment to convert a land well to a CO2 injector.


  • Identify the relevant technical issues
  • Propose a conceptual CO2 injection completion
  • Identify operational scope, risks and issues
  • Recommend a work unit
  • Develop an operational time estimate


  • Reviewed existing well status
  • Proposed a CRA liner / CRA completion
  • Reviewed design cases and identified test pressure for casings
  • Constructed time models, listed key risks and contingency time provisions
  • Recommended a light rig with power swivel


  • Condition of existing wellhead, wellhead specification break for CO2 injection
  • Mitigation of ongoing aquifer cross flow risks in sand-prone overburden
  • Mitigation of risk of external carbonic acid corrosion on existing carbon steel production casing above the production packer
  • Derated casing burst capacity based on metal thickness logs
  • Annulus fluid freezing during CO2 injection transient events
  • Balancing production casing burst risks versus design life of injector
  • Phasing of work to resolve key uncertainties at minimum committed cost


  • Concept level definition of workover scope, operational plan, times and risks
  • Framed further assessment of the balance between casing condition and burst capacity versus CO2 injection life
  • Framed initial mitigation strategies for key CO2 injection operations issues