Soil Characterisation for Installing and Operating Deep-Water Pipelines

2016 ◽  
Author(s):  
Antonio Borges Rodriguez ◽  
Vishal Dantal ◽  
Victor Bjorn Smith ◽  
Roselyn Carroll
Keyword(s):  
Deep Water ◽  
Site Investigation ◽  
Pipeline System ◽  
Accurate Assessment ◽  
Operational Conditions ◽  
Axial Forces ◽  
Seabed Topography ◽  
Water Pipelines ◽  
Efficient Planning ◽  
Touchdown Point

Deep-water developments rely on pipeline and riser systems to transfer hydrocarbon products to floating facilities or potentially longer tie-back pipelines to shallow water platforms/onshore facilities. Depending on the nature of the product and operational conditions, the pipeline and riser system design may need to consider a range of dynamic processes during operation such as (i) controlled lateral buckling of the pipeline in order to relieve excessive constrained axial forces induced by temperature and pressure changes in the system; (ii) the accumulation of pipeline axial displacement or ‘walking’; and (iii) evolution of the pipe-soil interaction at the riser seabed touchdown point due to the dynamic behaviour of the riser. Under these conditions, the reliable structural assessment of the pipeline system relies upon accurate assessment of the pipeline-soil interaction (PSI), from the initial lay embedment of the pipeline to the evolution of the lateral and axial response over the lifetime of the facilities. Accurate assessment of these PSI parameters requires adequate characterisation of the seabed topography, seabed processes (e.g. geohazards) and the soil properties. This paper proposes ways for efficient planning of the geophysical and geotechnical site investigation activities and subsequent soil element and physical model testing for the assessment of relevant PSI parameters in deep-water.

Numerical study on the lateral breakout behaviour of deep-water pipelines in clays with surficial crust

2020 ◽  
Vol 218 ◽  
pp. 108239
Author(s):  
Abhishek Ghosh Dastider ◽  
Neelanjan Sarkar ◽  
Santiram Chatterjee
Keyword(s):  
Deep Water ◽  
Numerical Study ◽  
Water Pipelines

Blockage Remediation in Deep Water Pipelines

2002 ◽  
Author(s):  
Ca´ssio Kuchpil ◽  
Marcelo A. L. Gonc¸alves ◽  
Antoˆnio C. P. Ferreira ◽  
Roberto S. Albernaz ◽  
Cla´udio S. Camerini ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Production Systems ◽  
Operational Conditions ◽  
Deep Waters ◽  
Water Pipelines ◽  
Pros And Cons ◽  
High Production ◽  
Organic Deposit ◽  
Production Losses ◽  
Exothermal Chemical

Flow assurance is an important issue in the design and operation of production systems in deep waters. The implementation of prevention and remediation methods is necessary mainly due to the low temperatures, high production pressures, long tie-ins and oils prone to organic deposit formation. Despite the development and improvement of these prevention and remediation techniques, failures or exceptional operational conditions can lead to the complete blockage of the submarine flowlines, risers or equipment. Although the complete blockage is not frequent, the related production losses generally are high; furthermore, the technical difficulties and the costs involved in the removal of blockages can be high. The steps to the remediation of subsea blockages are the localization, identification and removal methods. Due to the variety of problems, the different subsea layouts and surface facilities, it is not possible to have a general recipe for all problems. This paper presents some blockage remediation cases, including the localization and blockage remediation methods. The blockage localization methods used for the blockage removal cases described in this paper are the following: a) the echo of pressure pulses reflected at the blockage and b) a tool that detects the pipeline diameter variation with the pipeline pressure variations. The field results for these methods and the pros and cons of the methods are discussed. The remediation methods described are the following: external heating, internal intervention and exothermal chemical reaction using gravity.

Deepwater Pipeline Challenges

2015 ◽  
Author(s):  
Nitesh Sinha ◽  
Raj Kishore
Keyword(s):  
Deep Water ◽  
Oil And Gas ◽  
Deep Waters ◽  
Additional Manufacturing ◽  
Water Pipelines ◽  
Exploration And Production ◽  
Maximum Water ◽  
Mitigation Design ◽  
The Government ◽  
Increasing Demand

With the ever-increasing demand of energy in the country, the Indian exploration and production is now compelled to move into deepwater frontiers. The country’s energy reserve is getting exhausted with drying shallow water assets and the mainland is already overwhelmed with the pressure of sustaining the world’s second largest population. Therefore, “the upstream oil and gas fraternity of the country” has to now enter “less explored” Indian deepwater block which has already started with the launch of the NELP block by the government. Although, the world has moved into deepwater long back, the Indian industry is still developing the ways and means to tackle the challenges involved in deep water. This paper presents the insights into design and installation of deepwater pipelines along with case study of Middle East to India Deepwater Pipeline (MEIDP) of M/s SAGE, which shall be laid at a maximum water depth of 3450 m. This paper broadly elucidates the challenges in designing the deepwater pipelines such as requirement of thick-walled line pipes to sustain collapse due to external over-pressure and tensile stresses generated due to installation forces, pipeline route selection and optimization, geo-hazard assessment & mitigation, design against fault line crossings/ seismic design, free span, repair systems, seabed intervention etc. It also covers the additional manufacturing & testing requirements including tighter tolerances for line pipes suitable for deepwater installations. It also highlights the deepwater installation capabilities of Pipe lay Barges for the laying of pipeline in the deepwater to ultra-deep waters along with new evolving testing and commissioning philosophies. This paper intends to bring awareness among the “oil and gas fraternity” regarding challenges involved in deep water pipelines with respect to design, installation etc.

Justification of a Novel Pipe in Tunnel Approach to a River Crossing

2008 ◽  
Author(s):  
Chas Jandu ◽  
Mike Taylor ◽  
Stephen Humphrey
Keyword(s):  
River Estuary ◽  
Pipeline System ◽  
Directional Drilling ◽  
Tunnel Wall ◽  
River Bank ◽  
Operational Conditions ◽  
Finite Element Software ◽  
Soil Loading ◽  
Modelling Techniques ◽  
Fit For Purpose

As part of a major pipeline construction project, Laing O’Rourke had a requirement to install a section of pipeline beneath a river estuary. Due to a number of reasons it was not possible to negotiate the crossing using conventional techniques such as horizontal directional drilling (HDD) and an alternate method had to be sought. A feasibility study was undertaken and it was decided that a pipe-in-tunnel approach was the most viable. Due to constraints at the points of entry and exit it was necessary to cut two vertical shafts, one on each river bank. Linepipe sections were to be welded together, in the entry shaft, and pulled through the 2.44m diameter tunnel on plastic rollers, which were later to become the permanent supports during operation. On completion of the installation within the tunnel, two vertical sections of pipeline were to be installed in the shafts for connection to the main pipeline system. Due to the length of the crossing it was decided that back filling the void between the pipe and the tunnel wall with a suitable grout was not viable. A particular consideration was the likely occurrence of voids which would reduce the effectiveness of the CP system. For this reason, following installation, the tunnel was to be sealed with a concrete plug and flooded with water, and the shafts are to be backfilled with soil. This unique design arrangement presented a number of challenges and hence a requirement for the use of more complex modelling techniques than would normally be required. Models of the pipeline in various stages of installation were produced using the finite element software ABAQUS, with a variety of element types. Sets of rollers and their contact with the linepipe were also modelled. Soil loading, pressure, weight, buoyancy and temperature were applied to simulate a range of construction, commissioning and operational conditions. These were analysed, and the results were assessed for compliance with appropriate standards. Based on the results of the study it was possible to show that with a number of modifications to the original proposed design configuration, the crossing would be fit-for-purpose.

Feasibility Study of Lateral Buckling Using Residual Curvature Method for Deep Water Pipelines

2020 ◽  
Author(s):  
Qiang Bai ◽  
Fengbin Xu ◽  
Mark Brunner
Keyword(s):  
Deep Water ◽  
Twist Angle ◽  
Soft Clay ◽  
Soil Surface ◽  
Lateral Buckling ◽  
Finite Element Software ◽  
User Subroutine ◽  
Maximum Value ◽  
Water Pipelines ◽  
Residual Curvature

Abstract In recent years the residual curvature (RC) method has been used to provide buckle initiators to control and mitigate the lateral buckling of pipelines for some shallow water projects. With the appropriate planning of the controlled buckles using RC sections, an acceptable design of the pipeline in-place behavior is achieved. However, the RC method has not yet been applied to deep-water pipelines. The twist of RC sections in the sagbend during installation has been observed, and the orientation of as-laid RC section on the seabed is difficult to control in deep-water pipelines. The effects of as-laid RC-section orientation on in-place lateral buckling in deep water are unknown. The FRIC user subroutine in the Abaqus finite-element software suite has been developed for modelling pipe-soil interactions based on uncoupled axial and lateral soil resistances that are assumed to be independent of vertical pipe penetration after initial embedment into the soil surface. However, the penetration of a twisted RC section can vary dramatically from a normal pipeline on the seabed. The UINTER user subroutine in Abaqus was selected for presenting 3D pipe-soil interactions that incorporate the variations of independent axial and lateral soil resistances as a function of pipe penetration more accurately. UINTER is used in the present study to account for the effects of soil penetration on the lateral buckling performance of a pipeline with RC sections in soft clay. The analysis results show that the RC section twists in the sagbend area during installation, and the twist angle reaches its maximum value just prior to the RC section touching the seabed. The in-place lateral buckling analysis is carried out after the installation analysis is finished. The analysis results demonstrate the feasibility of applying the RC method as the primary buckle triggering mechanism for deep water pipelines, and it shows how the RC orientation affects the pipeline in-place performance in terms of strength and fatigue damage (only the stress ranges for use in fatigue calculations are shown in the paper).

Centrifuge Modeling of Axial Pipe-Soil Interaction of Deep-Water Pipelines

2019 ◽  
Vol 43 (1) ◽  
pp. 20180229
Author(s):  
U. Satchithananthan ◽  
S. N. Ullah ◽  
F. H. Lee ◽  
Z. Chen ◽  
H. Gu
Keyword(s):  
Deep Water ◽  
Centrifuge Modeling ◽  
Water Pipelines

scholarly journals Homopolar Pulse Welding for Offshore Deep Water Pipelines

1995 ◽  
Author(s):  
P. Haase ◽  
R.W. Carries ◽  
R.S. Hudson
Keyword(s):  
Deep Water ◽  
Water Pipelines ◽  
Pulse Welding

SEISMIC ANALYSIS OF OFFSHORE TRIANGULAR TENSION LEG PLATFORMS

2006 ◽  
Vol 06 (01) ◽  
pp. 97-120 ◽  
Author(s):  
S. CHANDRASEKARAN ◽  
A. K. JAIN ◽  
N. R. CHANDAK
Keyword(s):  
Deep Water ◽  
Seismic Analysis ◽  
Vertical Component ◽  
Vertical Direction ◽  
Gas Production ◽  
Hydrodynamic Drag ◽  
Environmental Loads ◽  
Axial Forces ◽  
Seismic Force ◽  
Seismic Forces

Oil and gas production from deep-water offshore fields represent a major structural engineering challenge for the industry. The tension leg platform (TLP) is a well-established concept for deep-water oil exploration. It is necessary to design an offshore TLP such that it can respond to moderate environmental loads without damage, and is capable of resisting severe environmental loads without seriously endangering the occupants. Seismic analysis of triangular TLP under moderate regular waves is investigated. The analysis considers nonlinearities due to the change in tether tension and nonlinear hydrodynamic drag forces. The coupled response of TLP under moderate regular sea waves due to change in initial pretension in the tethers caused by seismic forces (vertical direction) is then investigated. Seismic forces are imposed at the bottom of each tether as axial forces. The tether tension becomes unbalanced when the hull is under offset position. The vertical component of seismic force is an important item to take into consideration, because it is directly superposed to pretension of tethers. The change in initial pretension due to the vertical component of the earthquake affects the response of the triangular TLP in degrees-of-freedom experiencing such forces. The tether tension varies nonlinearly when the platform is subjected to seismic forces caused by the El Centro earthquake and artificially generated earthquake using Kanai–Tajimi's power spectrum. The response due to earthquakes varies with the intensity of the input ground motion. The seismic response of the triangular TLP exhibits nonlinear behavior in the presence of waves and it is non-proportionately influenced by the wave period and the wave height.

Modelling the axial soil resistance on deep-water pipelines

Géotechnique ◽  
2012 ◽  
Vol 62 (9) ◽  
pp. 837-846 ◽  
Author(s):  
M.F. RANDOLPH ◽  
D.J. WHITE ◽  
Y. YAN
Keyword(s):  
Deep Water ◽  
Soil Resistance ◽  
Water Pipelines
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