Abstract

Pipelines are major cost of items in the oil and gas field development. Poor on-bottom stability design may lead to fatigue, lateral and propagation buckling problems. Consequently, additional cost may be incurred during pipeline design and construction due to critical problems relating to poor design. But cost related to the on-bottom stability problem can be significantly reduced by optimizing design. This paper presents comparative review of submarine pipelines on-bottom stability design methods. Comparing absolute lateral stability, generalized lateral stability and traditional force balance methods show variation in submerged weight and effect of pipe-soil interaction on submerged weight parameters. Overall, most literatures agreed that pipelines lateral stability can be increased by increasing porosity of soil, soil embedment and submerged weight. But steel wall and concrete thicknesses are the major parameters used to establish lateral stability of submarine steel pipelines. Therefore, providing an in depth understanding of on-bottom pipeline stability design is necessary to prevent pipeline movement during operation, its associated risks and optimized design.Keywords: Displacement, lateral stability, on-bottom design, pipeline, submerge weight

Highlights

  • ABTSRACT: Pipelines are major cost of items in the oil and gas field development

  • This paper presents comparative review of submarine pipelines on-bottom stability design methods

  • Unlike the generalized lateral stability which does not take into consideration soil effect at the seabed, the absolute lateral static considers soil effect associated with load reduction by penetration, passive resistance force and frictional coefficient (Yu et al, 2013)

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Summary

Introduction

ABTSRACT: Pipelines are major cost of items in the oil and gas field development. Poor on-bottom stability design may lead to fatigue, lateral and propagation buckling problems. The dynamic analysis method involves full modeling of pipeline resting on seabed, soil resistance, hydrodynamic forces, boundary condition and structural response. The level 2 design Philosophy permits limited pipeline movement and involves computation of environmental loads effects, soil resistance force and pipe lateral displacement for design check (AGA, 2002). The aim of this work is to present systematic and analytical design methodologies for concrete and submerge unit weights required to withstand action of combined environmental and functional loads for carbon steel pipeline installation. Unlike the generalized lateral stability which does not take into consideration soil effect at the seabed, the absolute lateral static considers soil effect associated with load reduction by penetration, passive resistance force and frictional coefficient (Yu et al, 2013). Design equations which determine pipeline required submerged weight and concrete thickness that satisfy absolute static stability design criteria can be expressed as (DNV: 2010):. Submerged weight per meter length, can be expressed as (DNV, 1981): Basic Design Data: Basic metocean data for 100-year return condition in Forcados and Escravos fields of Nigeria in Gulf of Guinea region are presented in

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