Oslo, Norway, 3 May 2018: The recommended practice (RP) 'DNVGL-RP-E104 Wellhead fatigue analysis' has now been published. This publication is the result of a phase 2 joint industry project (JIP) involving 16 oil companies and supersedes the April 2015 edition of DNVGL-RP-0142.
The content of the updated RP provides specific recommendations on how to perform wellhead fatigue analysis in a consistent manner, and how to solve what have been considered as the main challenges related to wellhead fatigue analysis.
Proving sufficient margin to failure for drilling operations has been a growing challenge for the oil and gas industry over the last decade. Wellhead fatigue can have significant safety, technical and financial implications. DNV GL has for a long period and in close cooperation with industry partners addressed structural loading of offshore well systems and wellhead fatigue issues through an ongoing JIP.
The results from multiple technical analysis in the JIP project have been turned into specific recommendations to perform fatigue analysis. Examples are; rig motions including low frequency motion, BOP hydrodynamic properties, implementation of met ocean conditions, and how to represent damping in the global riser analysis.
Experience has shown that wellhead fatigue analysis conducted by different industry players has provided diverging results. By following the technical recommendations and the advice on improving quality in the analysis, it is expected that the industry will see more consistency and thereby confidence in the analysis.
While wellhead fatigue typically has been perceived as a North Sea concern, this JIP has benefited from the involvement of participants from both sides of the Atlantic resulting in the RP having a global application.
One of the JIP partners, David Baker, Engineering Associate, ExxonMobil Upstream Research, stated that “The JIP brought together numerous industry experts from around the world to forge an important updated guidance document on wellhead fatigue analysis. Contributions from operators, equipment manufacturers and engineering contractors were incorporated to ensure that current methods and techniques are represented and described. Early engagement and communication between a wide variety of stakeholders is imperative. This RP provides the common platform to initiate technical studies and facilitate the analysis process.”
This was echoed by Buba Kebadze, Sr. Technical Specialist, Subsea Wells, BP who said “Tremendous effort has been made over last few years by DNV GL and the JIP advisory board to navigate complexities in modelling for wellhead fatigue analysis and facilitate a multitude of approaches and viewpoints existing within different stakeholders in the industry to produce the final outcome. The resulting RP is the current state of knowledge in the industry for wellhead fatigue assessment.”
Liv A. Hovem, CEO, DNV GL - Oil & Gas stated” It is important to see the innovation and collaboration taking place and at DNV GL we provide a neutral ground for the industry to work through complex R&D challenges. Our 2018 Industry Outlook report has revealed an imminent turnaround in spending on R&D and innovation after three years of cuts and freezes. In the report more than a third (36%) of 813 senior sector players surveyed, expect to increase spending on R&D and innovation in 2018: the highest level recorded in four years. This is encouraging to see.”
The JIP participants were: AkerBP, BP, Centrica, Chevron, Engie, Eni, ExxonMobil, Hess, Lundin, Marathon, Nexen, Repsol, Shell, Statoil, Total and Woodside.
The following analysis houses have been collaborating with DNV GL in the execution of the technical studies: 2H Offshore Inc, 4Subsea, Kongsberg Maritime, Red Wing Engineering Inc., Stress Engineering Services Inc. and Woodgroup Kenny.