In collaboration with a local Mexican design house, DASH7 was engaged by PEMEX to undertake the predictive UHB and post installation out-of-straightness (OOS) analysis for the 20" x 12km HPHT oil and gas pipeline from Xikin-A to Xanab-C platform.

Project Background

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Installation of the 20"Ø x 12 km new oil and gas pipeline from the platform Xikin-A to Xanab-C is part of Pemex Exploration and Production strategy to increase the handling and transportation of hydrocarbons from the Xikin field, in addition contributing to satisfy the demand of the country. D7 Ltd in collaboration with EPESA is contracted by HOC Arendal to carry out UHB and OOS analyses and recommend UHB buckling mitigate measures for the Xikin-A to Xanab-C pipeline.

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Problem Definition​

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Upheaval buckling (UHB) is a major design concern for a trenched and buried pipeline operating at high temperature and pressure. Imperfections out-of-roundness (OOS) are naturally formed at the bottom trench profiles during post installation trenching activities. For buried pipeline conditions, expansion is restrained by the frictional resistance of the soil and causes the pipeline to be in compression, coupled with imperfection OOS curvature, the pipeline will tend to buckle upwards to relieve these forces and causing major overstress failure. 

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Scope of the Studies:

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DASH7 was involved the design and engineering to mitigate the upheaval buckling caused by trenching OOS imperfection. The studies involved:-

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• Prediction UHB analysis to OTC 6335 & DNV-GL-F110.

• Minimum Backfill cover design.

• Post installation out-of-straightness analysis.

• UHB mitigation design – rock dump and concrete mattresses download design.