How is Wellhead fatigue handled by industry standards?

Transcription

1 How is Wellhead fatigue handled by industry standards? Lorents Reinås Classification: Internal

2 Objective What is Wellhead Fatigue Industry standards for Wellheads Design approach in the industry standards Is this design approach suited for fatigue? Industry standards look-ahead 2 Classification: Internal

3 Today: 25 th march 1950 Ski jump competition in London An official said of the event: This exhibition has been such an unqualified success that we are very much hoping it will become one of the country's major sporting features *BBC archives: The competition was held on a specially-built ski jump on the Heath The ski-jump competition was never held again, despite several attempts to revive it. The ski-jump on Hampstead Heath was among the last major events to use real snow to re-create ski conditions. The first artificial snow was made two years later, in 1952, at Grossinger's resort in New York, USA. 3 Classification: Internal

4 What is Wellhead Fatigue? Environmental energy is absorbed and transmitted to the subsea well by the MODU, BOP and riser. Cyclic external loading of upper part of subsea well Resisted by material stresses in upper well region. Main symptoms expected in the wellhead system Exposure during drilling, not production 4 Classification: Internal

5 WH fatigue Fatigue is a time (usage) dependent deterioration mechanism Other time (usage) dependent deterioration mechanisms are Corrosion Wear HISCC 5 Classification: Internal

6 6 Classification: Internal

7 7 Classification: Internal

8 ISO Series Code Break 8 Classification: Internal

9 API ISO truce has ended 9 Classification: Internal

10 Timeline API 17D 10 Classification: Internal

11 ISO design approach Basically a pressure vessel design approach: pressure loads are used in design In ISO , section Design Method, it reads: The effects of external loads (i.e. bending moments, tension etc.) on the assembly or components are not explicitly addresses in this part of ISO or ISO As equipment covered by this part of ISO are exposed to external loads, ISO may be used to define the structural strength design. 11 Classification: Internal

12 Fundamentally Different Design Methodology ISO ISO Rated load method A component is rated for a pressure System integrator need to check loading vs. rating. Go/no-go decision Limit state method A component failure capacity is stated Component manufacturer states the limiting capacity The code gives utilization of limit System integrator to check system loads vs. component capacity Margin to failure is unknown on a system level Margin to failure is known on a system integration level 12 Classification: Internal

13 Well Integrity definition 13 Classification: Internal

14 Is the international design code for subsea wellhead equipment meeting regulatory expectations in Norway? No i.e need for additional requirements if an operator is purchasing subsea wellhead equipment for use in Norwegian waters. company specific type, but the future might bring more unified additional requirements Such work towards recommended practice documents is underway with the ongoing JIP 14 Classification: Internal

15 Regulatory bodies can impact standards WH products are designed and manufactured for a global market The design process is influenced by API Approx. 90 buyers of WH,s 4-5 WH suppliers 2 ways ahead: unified additional requirements amongst 90 buyers API to include guidance on system loads in design methodology US governmental pressure needed PTIL can make a difference 15 Classification: Internal

16 Further readings ISO ISO Wellhead Fatigue Analysis : Surface casing cement boundary condition for subsea wellhead fatigue analytical models Section 3: Reinås, Lorents PhD thesis can be downloaded at 16 Classification: Internal

17 17 Classification: Internal

18 How is Wellhead fatigue handled by industry standards? Lorents Reinås Leading engineer 18 Classification: Internal