University of Surrey

Test tubes in the lab Research in the ATI Dance Research

Effects of Seabed Interaction on Steel Catenary Risers.

Bridge, Christopher. (2005) Effects of Seabed Interaction on Steel Catenary Risers. Doctoral thesis, University of Surrey (United Kingdom)..

[img]
Preview
Text
13803830.pdf
Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (69MB) | Preview

Abstract

Steel catenary risers are an enabling technology for deepwater oil and gas production. A steel catenary riser consists of a steel pipeline suspended between the vessel and the seabed forming a catenary shape. Tools to analyse and design steel catenary risers show that the point where the steel catenary riser first touches the seabed, termed the touchdown point, has the highest stress and the greatest fatigue damage. Current understanding of pipe/soil interaction is limited and consequently there is concern within the industry regarding the conservatism of the analysis. In particular, the implications of pipe/soil interaction for maximum stress and fatigue damage at the touchdown point are significant. To address these concerns, research has been conducted into the following areas: Steel catenary riser trenches - using video survey data from installed steel catenary risers to determine the shape of seabed trenches. A steel catenary riser trench profile has been developed for use in finite element analysis. Pipe/soil suction force - i. e. the bond that forms between the riser pipe and a clay seabed. Experiments have been conducted and a pipe/soil suction model developed for use in steel catenary riser analysis. Pipe/soil stiffness - test data from the CARISIMA and STRIDE JIPs has been examined and a series of soil stiffness models for static penetration, small and large displacements, and cyclic loading have been developed for use in finite element analysis programs. Closed form and finite element models of steel catenary risers were constructed to determine the effect of the soil on stress and fatigue damage at the touchdown point. A finite element model of a representative steel catenary riser has been created and analysed using the seabed interaction models developed. The results show that the seabed trench, pipe/soil suction and soil stiffness have little effect on extreme stress in the steel catenary riser during normal operating conditions. However, pipe/soil suction is shown to have a large effect during slow drift motions where the stress in the riser at the touchdown point could double. The results from a closed form seabed model and finite element analysis show that the fatigue life of a steel catenary riser is sensitive to soil stiffness. If the soil stiffness used to model the seabed is too high the fatigue life may be underestimated; conversely, if the soil stiffness is too low the fatigue life may be over estimated.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Bridge, Christopher.
Date : 2005
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2005.
Depositing User : EPrints Services
Date Deposited : 30 Apr 2019 08:08
Last Modified : 20 Aug 2019 15:33
URI: http://epubs.surrey.ac.uk/id/eprint/851587

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year


Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800