Wellhead and Conductor Multi-Variate Fatigue Analysis for Old and New Subsea Wells
- Nicolas Pilisi (Blade Energy Partners) | David Lewis (Blade Energy Partners)
- Document ID
- Society of Petroleum Engineers
- IADC/SPE International Drilling Conference and Exhibition, 3-5 March, Galveston, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2020. IADC/SPE International Drilling Conference and Exhibition
- 1.7.5 Well Control, 1.6 Drilling Operations, 2.1.3 Completion Equipment, 3 Production and Well Operations, 4.1.5 Processing Equipment, 1.3 Wellhead design, 1.3.2 Subsea Wellheads, 3 Production and Well Operations, 1.7 Pressure Management
- capping stack, fatigue, conductor string, subsea wellhead
- 3 in the last 30 days
- 81 since 2007
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Deepwater wells historically have, and will continue to, push technological limits. Through the years, water depths and well depths have continued to increase. BOP's are now substantially larger than they were 20 years ago and casing string weights have also steadily and substantially increased. Additionally, since the Macondo incident 10 years ago, capping stacks have also been included in the design process. All of these developments have resulted in higher fatigue loads and an evolved conductor design, wellhead design and in some cases, inclusion of the 28″ pipe (secondary conductor) to support the 36″ conductor. But what about older wells? Wells that may need to receive a modern drill-ship for work-over, intervention or abandonment?
The objective of this paper is to answer the question posed and in doing so create an awareness of the ability for historical well designs to receive a modern BOP and capping stack – or not. In answering, this paper presents a case study of fatigue analysis performed on generalized modern and historical designs and their ability to receive a modern subsea BOP and capping stack. This paper examines the need for full and proper multi-variate fatigue analysis of existing and newly installed subsea wellheads and conductor strings for a set of subsea equipment, top of wellbore architecture, met-ocean and soil conditions. In performing this work, soil and metocean data were considered for the Mediterranean Sea, the Gulf of Mexico and West Africa.
In evaluating, a sample of well designs from 20 years ago through today was selected and a modern fatigue analysis workflow applied. It shows the engineering methodology for calculating and estimating the remaining fatigue life of existing and newly installed wellheads and conductors following the installation of a modern BOP and capping stack. The paper explores the important role of fatigue analysis and shares identified limitations. It also considers what physical factors may be modified to find an acceptable solution. In doing so, readers should get a sense for where potential issues may lie and consider the question of whether lighter BOP and / or capping stack solutions are a consideration for the future.
|File Size||3 MB||Number of Pages||29|