37 th Gas-Lift Workshop Houston, Texas February 3 – 7, 2014 Statoil Norne – A Case History on Long Term Barrier GLV Integrity Eric Lovie - Schlumberger Niek Dijkstra - Schlumberger Sean Dynes - Statoil 2014 Gas-Lift Workshop 1 Feb. 3 – 7, 2014
Agenda • Introduction • Statoil Norne Field • Gas Lift Equipment Used • Long Term Operating Conditions • Periodic Well Integrity Testing • Inspection of Pulled GLVs • Conclusion • Questions 2014 Gas-Lift Workshop 2 Feb. 3 – 7, 2014
Introduction 2014 Gas-Lift Workshop 3 Feb. 3 – 7, 2014
Statoil Norne Field • Subsea development 200 km (125 mile) from northern Norwegian coast • Water depth 380 m (1245ft) • Gas lift needed from day one to produce to Norne FPSO • Five gas lifted wells in initial phase (additional four well expansion ongoing) • Three water injection wells for pressure support and displacement • Exemption to omit Annular Safety Valve - > Need for “Barrier” GLV 2014 Gas-Lift Workshop 4 Feb. 3 – 7, 2014
Statoil Norne Field 2014 Gas-Lift Workshop 5 Feb. 3 – 7, 2014
Gas Lift Equipment Used 1- 3/4” OD X -Lift Orifice Gas Lift Valve – Designed for high gas injection rates – 350°F max / 32°F min – Check valve rated pressure - 10,000 psi – Venturi orifice size range – 8/64” to 32/64” – Premium body materials (Inc925) and elastomers 2013 Gas-Lift Workshop 6 Feb. 4 – 8, 2013
Gas Lift Equipment Used Reverse Flow Check Valve Venturi Orifice • • Venturi nozzle (21/64” used Positive seal, only open during flow from casing to tubing for most Norne wells) • • Metal-to-metal seal surfaces, no Optimized gas flow path elastomers • Critical flow achieved with • Modified geometry, flow velocity 10% delta pressure does not affect the check dart sealing surface 2014 Gas-Lift Workshop 7 Feb. 3 – 7, 2014
Long Term Operating Conditions • Initial 5 gas lifted wells installed 2005 and 2006 • Single point gas injection, unloading straight to orifice • Gas injection pressures range from 214 to 216 bar (3110 to 3140 psi ), well head pressure 43 bar (624 psi) • Gas injection depth ~2000 m (6500 ft) • Well production rates average from 850 to 1200 m3/d (5400 to 7550 bbls/d), water cut 20% to 60% • GOR ~ 50 m3/m3 (280 scf/bbl) • Gas injection rates range from 220,000 to 310,000 m3/d (8 to 11 mmscf/d ) 2014 Gas-Lift Workshop 8 Feb. 3 – 7, 2014
Long Term Operating Conditions 2014 Gas-Lift Workshop 9 Feb. 3 – 7, 2014
Periodic Well Integrity Testing • All gas lift valves periodically pressure tested, as with other down hole safety valves • Minimum 3 good monthly tests initially • Test interval increased to 3 months for the next 3 tests • Thereafter valves are tested once every six month • Acceptance criteria: – Gas: 0.42 Sm3/min (15 ft3/min) – Fluid: 0.4 L/min (400 cc/min) – zero pressure build up over 6 hour hold period • Pressure differential recommendation for integrity test 70 bar (1000 psi) 2014 Gas-Lift Workshop 10 Feb. 3 – 7, 2014
Periodic Well Integrity Testing 2014 Gas-Lift Workshop 11 Feb. 3 – 7, 2014
Inspection of Pulled GLVs J-2 Valve: Installed 2006, Pulled 2011 (no failure) 2014 Gas-Lift Workshop 12 Feb. 3 – 7, 2014
Inspection of Pulled GLVs J-4 Valve: Installed 2006, Pulled 2012 (no failure) 2014 Gas-Lift Workshop 13 Feb. 3 – 7, 2014
Conclusions • The recovered GLVs are some of the newer “Barrier” type design valves with the longest track record • The 1- 3/4” X -Lift GLVs have been providing long-term reliability under harsh operating conditions. • After periods of 5 and 6 years operating down hole, without failure, the condition of critical components such as back check dart and sealing surfaces were in excellent condition. • The long duration of exposure gives an indication of wear and tear, as well as performance, that provides lessons learned to further enhance the latest developments in gas lift valve design. 2014 Gas-Lift Workshop 14 Feb. 3 – 7, 2014
Questions 2014 Gas-Lift Workshop 15 Feb. 3 – 7, 2014
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