Project Background

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PEMEX has proposed a new transport system through a 16" x 2.527 km pipeline from the Pokché-C to Pokché-A platform. With the construction of the new pipeline, a production of 24 MBPD of oil and 29 MMPCSD of gas can be transported. The project is in the territorial waters of the Bay of Campeche. The pipeline is trenched and buried to protect against fishing trawl gear interaction.

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Problem Definition​

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The Pokché pipeline an HPHT pipeline with max. operating pressure and temperature of 130°C and 70bar. One of the major concerns for a trenched and buried pipeline operating at high temperature and pressure is Upheaval Buckling. Out-of-roundness (OOS) imperfection are formed at the bottom trench profiles during post installation trenching activities. For a buried pipeline, expansion is restrained by the surrounding soil causing the pipeline to behave in compression manner, coupled with imperfection prop curvature, the pipeline will tend to buckle upwards to relieve the compressive forces causing major bending 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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• Minimum backfill cover design.

• Out-of-straightness survey raw data review and smoothing.

• Post installation out-of-straightness (OOS) analysis.

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

• Rock berm and concrete mattresses stability assessment.