The Python Subsea Wellhead Craig Hendrie, Technical Director, Plexus Holdings plc. COPYRIGHT. All rights reserved. Plexus Holdings plc.
Subsea Wellhead challenges - 2010 Following the Macondo disaster in 2010, there was increased scrutiny on the design and operation of Subsea Wellhead Systems for deepwater drilling and production. Issues included: - Casing Hanger instant lockdown - Casing Hanger lockdown capacity - Hanger and annular seal integrity - Overall system safety and efficiency
Joint Industry Project - 2011 In 2011, a JIP was initiated to design, build and test a new generation of subsea wellhead equipment, with the following targets. - Full system life of field qualification testing - Resolve casing hanger lockdown issue - Improve drilling and production safety and efficiency. - Full 18-3/4 15k, 350 degf capability - Consider X-HPHT upgrades The JIP was supported by the following:
POS-GRIP Technology POS-GRIP friction grip technology was selected as the basis for the new subsea wellhead. POS-GRIP works by elastically deflecting the bore of a wellhead inwards to grip and seal on the hangers inside. The technology had already been proven on 300 surface wellheads, primarily HPHT up to 20,000 psi. POS-GRIP Open POS-GRIP Closed
JIP complete system delivered 2015
Python Subsea Wellhead system key features 15ksi rated easily upgradable 20ksi 0-350 deg F rated easily upgradable -20 to 450 deg F Hanger Lockdown and Hanging Capacity of 6Mlbs System Bending Capacity of 7Mft.lbs No wearbushings or lockdown sleeves No packoffs Instant hanger lockdown Several days per well operational time saving System fully qualified to genuine life of field standards
Animation key steps Note: Animation will not run in pdf copy of this presentation. For access to the sequence please contact Plexus.
Subsea Wellhead Performance Verification Industry Standards API 17D API 6A PR2, Annex F API 6HP RP - API PER15K - API 17 TR8 For wellhead casing hangers and annular seals: Individual components tested and certified Annular Seals 3 pressure and temperature cycles Real world field conditions For wellhead casing hangers and annular seals: Entire system must work together! Hundreds or thousands of pressure, temperature and load cycles. Fatigue affects entire system, not just primary housings. Hanger capacity and lockdown 3 load cycles
Wellhead systems effect of annulus pressure = MOVEMENT = NO MOVEMENT Annulus pressure effect on wellhead seal system External pressure effect on casing coupling
Subsea Wellhead Annular seal testing to API 6A
Python performance verification testing 3 simultaneous full system test systems test programs 12 months of testing
LP Housing qualification 7 millions ft-lbs bending
Life of field testing HP Housing / Hanger / Annular seal system Python wellhead performance envelope: API 6A Annex F: 15,000psi, 0 to 350 degf plus Best and worst case tolerance stackups. 7 combined temp/press/load points 20 max lockdown cycles
Testing matching premium casing couplings POS-GRIP HG Sealing Systems also tested to casing coupling standards Tested to ISO 13679 CAL IV 20,000 psi, 350 degf Performance envelope defined by combined Internal/external pressure. Hanger tension/compression Bore/annulus pressure Min/max temperatures
Python configuration options Single String System Hybrid System Dual String System
Annulus pressure management Internal seal sleeve, and porting to tubing hanger can provide full and permanent hydraulic access from B and C annuli. Annulus Monitoring + Annulus Access = Annulus Management
Conclusions JIP a success and Python subsea wellhead is ready Surpasses industry standard qualification requirements Full worst case life of field performance verification Proven for15ksi, 0-350 deg F true field life Hanger Lockdown and Hanging Capacity of 6Mlbs System Bending Capacity of 7 Mft.lbs Annulus access capable Simpler, quicker, safer system
Questions? Slide 18