Influence of Anchoring on Burial Depth of Submarine Pipelines.

Yuan Zhuang,Wei Su,Yang Li,Myung-Il Roh

doi:10.1371/journal.pone.0154954

Abstract

Since the beginning of the twenty-first century, there has been widespread construction of submarine oil-gas transmission pipelines due to an increase in offshore oil exploration. Vessel anchoring operations are causing more damage to submarine pipelines due to shipping transportation also increasing. Therefore, it is essential that the influence of anchoring on the required burial depth of submarine pipelines is determined. In this paper, mathematical models for ordinary anchoring and emergency anchoring have been established to derive an anchor impact energy equation for each condition. The required effective burial depth for submarine pipelines has then been calculated via an energy absorption equation for the protection layer covering the submarine pipelines. Finally, the results of the model calculation have been verified by accident case analysis, and the impact of the anchoring height, anchoring water depth and the anchor weight on the required burial depth of submarine pipelines has been further analyzed.

Highlights

Due to an increase in exploration of domestic marine oil and gas resources, there have been more submarine pipelines constructed which is resulting in more obvious damage due to ship anchoring operations [1,2,3]
The results of the model calculation have been verified by accident case analysis, and the impact of the anchoring height, anchoring water depth and the anchor weight on the required burial depth of submarine pipelines has been further analyzed
Researchers in Norway and Japan are leading in this area, and the research of Det Norske Veritas (DNV) on protection technology for submarine pipelines is at an internationally advanced level [8]

Summary

Introduction

Due to an increase in exploration of domestic marine oil and gas resources, there have been more submarine pipelines constructed which is resulting in more obvious damage due to ship anchoring operations [1,2,3]. Regards to v2 and the anchor weight m, the energy of the impact on the submarine pipeline can be determined for deep water anchoring operation by:. A manual sandstone burial method is employed to protect submarine pipelines and effectively prevent their damage due to anchor-dropping and other falling objects. Solve the simultaneous Eqs (15), (20) and (21), and substitute the parameters to obtain: 37136 1⁄4 0:5Ã11 Ã 103Ã0:2731Ã137Ã0:059Ãz1 þ 11 Ã 103 Ã99Ã0:059Ãz12 This approach was used to calculate the impact energy and the corresponding reasonable burial depth of submarine pipelines when an anchor falls from 2m height into water depths of 10m, 15m and 20m, respectively. The same approach was used to calculate the impact energy and the corresponding required burial depth of the submarine pipes for deep anchoring of anchors with different weights.

Discussion

Conclusions