AYIN - ALUX Pipeline Lateral Study

Year:
2016

Client:
PEMEX

Region:
Gulf Of Mexico

Business Unit:
Subsea / Pipeline

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DASH7 in colaboration with Local Mexico Consultant was engaged by PEMEX to undertake the lateral buckling detailed engineering for the 20" HPHT pipeline from subsea tree to the host platform. The project was the first lateral buckling studies for PEMEX in Gulf of Mexico.

Project Background

Alux Ayin is Pemex's first project in the deeper water region of around 200 metres water depth. The field was discovered some years ago but the development was delayed by porject CAPEX sanction. The project development strategy consist installation of subsea wells and tie-back to the processing platform facilities at close proximity.    

Problem Definition

Lateral buckling phenomenon is a common problem for pipelines exposed on the seabed subjected to high pressure and high temperature (HPHT) condition. The restrained section of the pipeline will become compressive due to the seabed resistance influences on increments of the effective axial force. Coupled with any imperfection along the pipeline route, lateral buckling will be triggered when the compressive force along the line exceeds the buckling force threshold. Accordingly, uncontrolled global buckling can cause excessive plastic deformation of the pipeline, which could lead to localized buckling collapse or cyclic fatigue failure during operation, if it is not properly managed or studied. 

Features of the Studies:

DASH7 was involved the definition and FEED of the 20" pipeline HPHT lateral buckling studies. The features of the studies involved are:-

  • Lateral buckling susceptible screening studies to Hobb's Theory.

  • Tolerable virtual anchor spacing studies.

  • Controlled lateral buckling mitigation - Snake Lay.

  • Pipeline walking study - Cyclic operation. 

  • Full seabed and geophysical modelling.