Background:

Because gas lift valves were considered primary well barrier devices by a North Sea producer, it was necessary to test these valves on a prescribed schedule. The costly and dangerous testing procedure involved well intervention and setting plugs to discover potential leaks.

Gas Lift Valves As Barrier Devices

gas lift valves

  1. Are gas lift valves really barrier devices?
  2. Would well safety be compromised if gas lift valves failed?
  3. Are gas lifted wells with annulus safety valves and SCSSVs actually safer when gas lift valve testing is not required?

Findings from WellMaster queries were used in a quantitative risk assessment to address key questions. What percentage of well blowouts occur during the production phase versus the drilling, completion or work-over phases? What is the relationship of offshore well blowouts to gas lift valve failure? What is the relationship of well blowouts to ASV failure? What is the relationship of well blowouts to SCSSV failure?

Project Outcome:

 
  • Very small percentage of well blowouts occur during the production phase
  • No correlation was found between gas lift valve failure and blowout rates
  • Producer was able to change its testing procedures for gas lift valves

Estimated value:

 

saving production, well intervention costs and increasing well reliability