Transcript Attachment 34 - API Presentation - Worst Case Discharge - No Notes

API Consideration for
Worst Cast Discharge
Bruce Witwer, Dril-Quip Inc.
Definitions
Definitions
• Survival Loads
– Watch circles
– Storm events
– Repeatable (probabilistic)
• Worst Case Loads/Discharge (WCD)
– Drive-off
– Blowout/uncontrolled flow
– One time event (stochastic)
• Allowable stress scenarios (ref. API 17G/2RD)
– Rated = .67 (σY)
– Extreme = .80 (σY)
– Survival = 1.00 (σY)
WCD - Example #1
• Blowout/uncontrolled flow
• Casing hanger & seal
– Pressure control (rated)
– Lockdown load (beyond rated)
– Current industry standards
• API 17D/6A (group 4)
• Cyclic loads (rated)
• Cyclic thermal
WCD - Example #2
• Blowout/uncontrolled flow
• Liner hanger & packer
– Pressure control or containment
– Lockdown load
– Current industry standards
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API 11D1
API 19 LH (pending)
Cyclic thermal
Inconsistent terms, failure modes
WCD - Example #3
• Drive-off event
• Wellhead System
– Pressure containment (rated)
– Structural capacity (beyond rated)
– Current industry standards
• N/A
• Proposal
– Survival (ALS) event
• API 17G & API 2RD
– 1.00 (σY)