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Changes in pipeline embedment due to sediment mobility: Observations and implications for design

Changes in pipeline embedment due to sediment mobility: Observations and implications for design
Changes in pipeline embedment due to sediment mobility: Observations and implications for design

This paper describes temporal variations in embedment of several existing pipelines on the North-West Shelf (NWS) of Australia, and the sediment mobility processes that cause them. Distinct and explainable patterns in the extent, distribution and rate of the development of pipeline embedment have been revealed through systematic detailed examination of repeated annual integrity surveys by ROV. This represents a unique data-set that has been used to optimize the reliability of a newly designed pipeline. This paper explains why these clear findings should not be overlooked in both the buckling and stability design of initially unburied pipelines, which is in contrast to currently established industry practice. This new information supports the presumption that conventional approaches for calculating the hydrodynamic stability of unburied pipelines may be more conservative than necessary. Conversely, and arguably more importantly, it is shown that conventionally accepted methods for calculating pipe-seabed resistance forces when planning buckling schemes should be considered unsafe if embedment due to sediment mobility is possible. Consequently, this paper proposes an innovative calculation methodology that statistically captures these sediment mobility effects, and which facilitates a more justifiable geotechnical input to pipeline engineering than what is conventionally adopted. This methodology is currently being used by the authors as a state-of-the-art design practice for unburied offshore pipelines in regions of sediment mobility.

American Society Of Mechanical Engineers (ASME)
Rodriguez, Antonio Borges
be4c974c-6623-49fa-9668-6fd43d3a7c9d
Bransby, M. Fraser
9d0088f1-0395-4279-9bf1-9e079fd1357a
Finnie, Ian M.S.
e7c790f5-0b47-4a83-af3e-6d844db15d73
Low, Han Eng
8a9ab90a-edd1-46a0-8355-cdd888f40cf7
White, David J.
a986033d-d26d-4419-a3f3-20dc54efce93
Rodriguez, Antonio Borges
be4c974c-6623-49fa-9668-6fd43d3a7c9d
Bransby, M. Fraser
9d0088f1-0395-4279-9bf1-9e079fd1357a
Finnie, Ian M.S.
e7c790f5-0b47-4a83-af3e-6d844db15d73
Low, Han Eng
8a9ab90a-edd1-46a0-8355-cdd888f40cf7
White, David J.
a986033d-d26d-4419-a3f3-20dc54efce93

Rodriguez, Antonio Borges, Bransby, M. Fraser, Finnie, Ian M.S., Low, Han Eng and White, David J. (2013) Changes in pipeline embedment due to sediment mobility: Observations and implications for design. In Proceedings of the ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2013): Volume 4B: Pipeline and Riser Technology. vol. 4 B, American Society Of Mechanical Engineers (ASME).. (doi:10.1115/OMAE2013-11425).

Record type: Conference or Workshop Item (Paper)

Abstract

This paper describes temporal variations in embedment of several existing pipelines on the North-West Shelf (NWS) of Australia, and the sediment mobility processes that cause them. Distinct and explainable patterns in the extent, distribution and rate of the development of pipeline embedment have been revealed through systematic detailed examination of repeated annual integrity surveys by ROV. This represents a unique data-set that has been used to optimize the reliability of a newly designed pipeline. This paper explains why these clear findings should not be overlooked in both the buckling and stability design of initially unburied pipelines, which is in contrast to currently established industry practice. This new information supports the presumption that conventional approaches for calculating the hydrodynamic stability of unburied pipelines may be more conservative than necessary. Conversely, and arguably more importantly, it is shown that conventionally accepted methods for calculating pipe-seabed resistance forces when planning buckling schemes should be considered unsafe if embedment due to sediment mobility is possible. Consequently, this paper proposes an innovative calculation methodology that statistically captures these sediment mobility effects, and which facilitates a more justifiable geotechnical input to pipeline engineering than what is conventionally adopted. This methodology is currently being used by the authors as a state-of-the-art design practice for unburied offshore pipelines in regions of sediment mobility.

Full text not available from this repository.

More information

Published date: 2013
Venue - Dates: ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2013, Nantes, France, 2013-06-09 - 2013-06-14

Identifiers

Local EPrints ID: 420227
URI: https://eprints.soton.ac.uk/id/eprint/420227
PURE UUID: 5bd1796e-5270-41c7-9c2a-7e10dc20f1ed
ORCID for David J. White: ORCID iD orcid.org/0000-0002-2968-582X

Catalogue record

Date deposited: 02 May 2018 16:30
Last modified: 18 Jul 2019 00:25

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