DOCSLIB.ORG

Marine Pipe Laying Methods

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Marine Pipe Laying Methods SOCIETYOF PETROLEUXENGINEERSOF AIME PAPER ~ZOONorthcentralExpressway NUMBER SPE 2278 Emllas,Texas 7’j2C6 THISIS A PREPRINT---SUBJECTTO COR.RECTIO~~ Marine Pipe Laying Methods Downloaded from http://onepetro.org/SPEATCE/proceedings-pdf/68FM/All-68FM/SPE-2278-MS/2063248/spe-2278-ms.pdf/1 by guest on 25 September 2021 By JollyDwyer,MemberAIME,BechtelCorp.,SanFrancisco,Calif. @ Copyright 1968 American Institute of Mining, Metallurgical and Petroleum Engineers, Inc. Thispaperwaspreparedforthe43rdAnnualFallMeetingof theSocietyof PetroleumEngineers of AIKE,to be heldin Houston,Tex.,sept. Zg-od. 2, 1968.Permissionto copyis restrictedto an abstractof notmorethan300words. Illustrationsmaynotbe copied.The abstractshouldcontain . usuallygranteduponrequestto theEditorof the appropriatejournalprovidedagreementto give propercreditis made. Discussionof thispaperis invited.Threecopiesof anydiscussionshouldbe sentto the Societyof PetroleumEngineersoffice.Suchdiscussionmaybe presentedat theabovemeetingand, withthepaper,maybe consideredforpublicationin oneof thetwoSPEmagazines. ABSTRACT A number of marine pipelaying laying pipe in deep water. It techniques have developed over the suggests that economical solutions to years, but their potential for in- those problems are within the stalling large diameter pipe in deep capability of present day technology, water is severely limited. A survey without excessive developmental of present day technology is desir- effort. able to evaluate its limitations for the needs at hand, and to determine INTRODUCTION where new techniques are required. All present day techniques have When petroleum discoveries many elements in common. These can stepped from dry land into the be com:~edt~ a variety of ways, and marshes, and eventually into the sea, some combinations offer the associated pipelines had to go possible solutions to the problems of into the water as well. Short lines laying pipe in deep water. in shallow water could readily be This paper describes the most made up on shore and pushed or pulled common components of marine into position. However, long pipe- pipelaying systems, and discusses the lines, even through marsh lands, re- present day combinations. The quired a different solution, and the components include: barges, pipelaying spread took to the water stingers, launchways, reels, winchesD on a lay barge. From these begin- tensioners, pontoons$ caissons, nings various marine pipelaying chambers and submersible vehicles. methods have evolved and are in use The combinations include: lay today. barges, tie-in barges, lowering As the need grows to lay pipe- barge;fiereelbarges, and pull barges. lines of larger diameter in deeper paper then goes on to water, even present day techniques describe the potential appMcations are becoming restrictive. It is of other systems to the problems of desirable to examine present day marine pipelaying technology closely References at end of paper. and to evaluate its potential for 2 MARINB PIPE LAYINGMETHODS SPB-2278 Downloaded from http://onepetro.org/SPEATCE/proceedings-pdf/68FM/All-68FM/SPE-2278-MS/2063248/spe-2278-ms.pdf/1 by guest on 25 September 2021 Fig. 1 - Conventionalbarge. Fig.2 - Semisubmersiblevessel. C- Fig. 3 - Straightlaunchway. Fig.4 - Shapedlaunchway. Fig. 5 - Straightstinger. Fig.6 - Shapedstinger. 1 c -~ = @ ‘- Fig.7 - Tensioner. Fig.8 - Winch. >E.2278— JOLLY DWYER ~ ————. —...—. “ forthcoming needs. It isw~;~e desir- matter of expediency in providing an able to determine new inexpensive hull. The shipform techniques might be required to vessel has a definite mobilization overcome the ultimate limitations of cost advantage, because it tows well. present day methods. However its stability is seldom any The next two sections of this better than a barge?s, and can be paper are intended to acquaint the worse. interested engineer with the Semisubmersible vessels (Fig. 2) pipelaying art if he “ are uncommon in marine pipelaying, unfamiliar with it. For t&e ~h~ but are well known in the drilling already know mari;;e pipelaying, a industry. Their stability is good, Downloaded from http://onepetro.org/SPEATCE/proceedings-pdf/68FM/All-68FM/SPE-2278-MS/2063248/spe-2278-ms.pdf/1 by guest on 25 September 2021 glance through accompanyingg even in high seas. illustrations will tell the story in adequate detail. Assemblyway COMPONENTS The assemblyway is an area in which the pipe can be aligned and At present the pipe is generally joined into one continuous string. joined at the surface. Consequently It is horizontal when possible, and the techniques have many surface- strai~ht in any case, so that locked- oriented elements in common: working in bending stresses are minimized. platforms; pipe handling, joining and On shore it is usually alongside the launching equipment; and vessel Iaunchway, and the pipe string is positioning equipment. Additionally rolled from one to the other. At sea a number of underwater elements are it is generally in line with the available for use in a system when Iaunchway. desired. Divers are the most common, but chambers and submersible vehicles Launchway have increasing application. The Iaunchway serves to transfer Pipelaying Equipment the fabricated pipe string from the assemblyway into the sea. It is an Whether ashore or at sea, the integral part of the working pipeline has to be fabricated joint platform, although it may be designed by joint. There must be storage to assume different angles racks and an assemblyway; there must configurations. It may be a straig~~ be carriers and a launchway. At sea extension of high-angled a stinger may be used, to carry the assemblyway (Fig. 3;, or it may b~h~ pipe from the vessel to the sea curving transfer system carrying bottom. Pulling winches are pipe from a shallow angle on the required, to pull the pipe from the assemblyway to a steep angle at the land into the sea, or from the barge launching point (Fig. 4). toward the land. Holdback devices may be employed, to keep the pipe Stinger from running down the launchway. There may also be tensioning machines The stinger is unique to the lay to apply horizontal force to the barge. It is a detachable extension pipe. of the launchway, intended to support the pipeline during its descent from Working Platforms the barge to the sea floor. It may be a truss framework firmly attached The most stable working platform to the barge, or a buoyant pipe of all is the land, of course, and it ladder hinged to the barge. It lUay is put to use as a pipe fabrication be straight (Fig. 5), or shaped for base when suitable. More fre uently some purpose (Fig. 6), usually to a seagoing platform is require8, and hold the overbend in the pipe to an a vessel is employed for the purpose. allowable stress limit. Conventional flat-bottomed barges (Fig. 1) are in common use. Tensioner They are relatively low in cost, but have poor characteristics as stable By applying appropriate tension platforms in a seaway. to the pipe, the stinger may be Ships are sometimes converted to shortened, or even eliminated if the pipelaying vessels, usually as a launching angle can be adjusted. 4 MARINH PIPE LAYINGMETHODS SPE-2278 Downloaded from http://onepetro.org/SPEATCE/proceedings-pdf/68FM/All-68FM/SPE-2278-MS/2063248/spe-2278-ms.pdf/1 by guest on 25 September 2021 Fig, 9 - Pipereel. Fig. 10 - Pontoon. w 5!? Fig. 11 - Anchor, Fig. 12 - Positioner. Fig. 13 - Tug. Fig. 14 - Diver. Fig. 15 - Chamber. Fig, 16 - Submersible, )E.2278— JOLLY DWYER I During the welding operation on a lay Positioners may be fully barge, the pipe is gripped firmly, so rotatable right-angle propeller drive that tension must be applied through units (Fig. 12), combinations of main the barge positioning system. When propellers and tun~fl thrusters, or the barge moves forward to launch a other types special marine joint of pipe, however, the pipeline propulsion systems. must be fed out “ continuous tension, and the ten;?oner (Fig. 7) Auxiliary Components comes into play. It maintains a fixed amount of holdback on the The tug (Fig. 13) is the gener- Downloaded from http://onepetro.org/SPEATCE/proceedings-pdf/68FM/All-68FM/SPE-2278-MS/2063248/spe-2278-ms.pdf/1 by guest on 25 September 2021 running pipe until the barge reaches al purpose workhorse of the marine its new position, where the positive pipelaying spread. It tows the stop is reset. equipment to the work site, hauls the pipe barges back and forth, moves the Winches anchors, and performs a number of other routine chores. Although a necessary part of an The diver (Fig. 14] is often a anchor positioning system, a winch necessary adjunct to the pipelaying (Fig. 8) is even more vital for operation., Routinely he sets and ad- :~;;:ne i.nstallati.onsby the pull justs the stinger; he ties in flanged where a heavy-duty winch, connections; and he inspects the someti~es capable of l,inepull in the pipeline in place. More importantly 200-ton range or greater, may be he serves as the solution for most required. underwater emergencies: clearing fouled anchors; recovering lost Pipe Reel equipment; and removing obstructions. The open-bottom dry chamber Pipe can be spooled into (Fig. 15), cl~~~ng to Alexander the radius of curvature in the yiel~ Great in and at least to the range and then can be straighten~~ 17th Century in fact, has just lately through the yield point arrived on the pipeline scene. Its unspooled,. with no appreciable change primary use has been for hot taps and dimensional characteristics. repairs, but it shows potential for &ge-diameter reels (Fig. 9) are pipelaying. used to spool pipe for this purpose, Also a newcomer to pipelining, and offer a convenient way to carry and not yet proven for any purpose great lengths of prefabricated but inspection, is the manned sub- pipeline in a small area. mersible vehicle (Fig. 16). Its un- manned counterpart”, the tethered Pontoons vehicle, has only recently flexed its pipelaying muscles, but may some day A sim~?le method to reduce the be a routine part of the operation.
Load more

Recommended publications
  • Subsequent Initial Study of Environmental Impact
    Cayucos Sanitary District 200 Ash Avenue Cayucos CA 93430 www.cayucossd.org • 805-773-4658 Cayucos Sustainable Water Project (CSWP) Subsequent Mitigated Negative Declaration for the Estero Marine Terminal Ocean Outfall Project Component Subsequent Initial Study of Environmental Impact I. ENVIRONMENTAL DETERMINATION FORM 1. Project Title: Cayucos Sustainable Water Project Ocean Outfall 2. Lead Agency Name and Address: Cayucos Sanitary District 200 Ash Avenue / PO Box 333 Cayucos CA 93430 3. Contact Person and Phone Number: David Foote, c/o firma, (805) 781-9800 4. Project Location: Chevron Estero Marine Terminal 4000 Highway 1, Morro Bay, California 93442 5. Project Sponsor's Name and Address: Cayucos Sanitary District 200 Ash Avenue / PO Box 333 Cayucos CA 93430 6. General Plan Designation: The proposed pipeline tie-in site is designated Agriculture. The effluent pipeline conveyances are within public right-of-way (State Route 1) and Waters of the U.S. and State. 7. Zoning: Agriculture (County) and Open Area I/PD (City of Morro Bay west of State Route 1 and the mean high tide line) Cayucos Sustainable Water Project Ocean Outfall Initial Environmental Study Final January 2019 1 Cayucos Sanitary District 200 Ash Avenue Cayucos CA 93430 www.cayucossd.org • 805-773-4658 Cayucos Sustainable Water Project (CSWP) Subsequent Mitigated Negative Declaration for the Estero Marine Terminal Ocean Outfall Project Component 8. Project Description & Regulatory and Environmental setting LOCATION AND BACKGROUND The Project consists of the reuse of an existing ocean conveyance pipe for treated effluent disposal from the proposed and permitted Cayucos Sustainable Water Project’s (CSWP) Water Resource Recovery Facility (WRRF) by the Cayucos Sanitary District (CSD).
    [Show full text]
  • Subsea Pipelines Collaboration Cluster Advancing Our Knowledge of Subsea Pipeline Technology to Support the Oil and Gas Industry
    WEALTH FROM OCEANS www.csiro.au Subsea Pipelines Collaboration Cluster Advancing our knowledge of subsea pipeline technology to support the oil and gas industry Final report 2 Executive summary 17 Putting the Cluster’s research into practice 4 Introduction to the Subsea Pipelines Cluster 21 Commissioning experimental equipment 6 Training the offshore for ongoing pipeline pipeline engineers testing in Australia of the future 28 Publications and 10 Scientific and dissemination engineering challenges 34 Key papers 12 Scientific outcomes of the Flagship 46 Awards Collaborative Cluster 48 Keynote presentations, invited lectures and papers 49 Hosting international conference ISFOG 50 The Partners 51 Flagship Collaboration fund 1 Executive summary Offshore subsea pipelines are used to export oil and gas from the field to platform and then from the platform to the mainland. As they are the sole conduit for the hydrocarbons their stability and integrity are of critical economic and environmental importance. More than 80 per cent of Australia’s gas resources exist in deep, remote, offshore areas and being able to realise the full potential of these remote resources relies on the development of economically viable transportation solutions. Technical solutions for Australia’s offshore pipelines must maintain structural integrity and continuous supply of products across hundreds of kilometres of seabed. Such technology is also vital to Australia achieving the vision of “platform free fields”, a CSIRO Wealth from Oceans Flagship initiative. Platform free fields research investigates ways to replace traditional oil and gas platforms with subsea technologies for production of gas resources which may lie as far as 300 km offshore, at a depth greater than 1 km.
    [Show full text]
  • Method of Determining
    Hydrotransport 19 Conference, Sept 24-26, 2014, Denver, USA Options for fixed mechanical sand bypassing at river entrances N.T. Cowper1, L. Nankervis2 and A.D. Thomas3 Slurry Systems Pty Limited, Sydney, Australia 1, [email protected] 2, [email protected] 3 [email protected] ABSTRACT Littoral drift of sand along coastlines can result in sand bars forming off ocean entrances causing navigational problems. Conventional management of these sand bars involves regular dredging. Two alternative fixed sand bypassing technologies are considered. The world’s first large scale fixed bypass system at Nerang, Queensland, Australia, is described. Since 1986 it has bypassed around 17 million m3 of sand. The system consists of 10 jet pumps mounted along an offshore jetty. An alternative option, not requiring a jetty, is to use a Submarine Sand Shifter (SSS) buried beneath the sand. The development, pilot plant testing, and operational experience of the Sand Shifter is described. 1. INTRODUCTION Littoral drift is a natural process due to sand being suspended by the energy dissipated in breaking waves. The resulting sand movement is predominantly towards the beach shore. However, when waves strike the beach at an oblique angle there is a shore parallel component of sand movement, or littoral drift. The quantity of littoral drift sand varies depending on wave climate. Depending on the prevailing wave direction, sand bars may build up across river entrances, inhibiting navigation. The conventional solution involves regular dredging of the entrance. A fixed sand bypassing system can provide a more economical alternative. Fixed sand bypassing involves a system to intercept the littoral drift sand before it reaches the entrance and pump it ashore to an on-shore pump station.
    [Show full text]
  • Hydrodynamic Forces on Subsea Pipes Due to Orbital Wave Effects
    Hydrodynamic Forces on Subsea Pipes due to Orbital Wave Effects Lisa King Jeremy Leggoe1, Liang Cheng2 1School of Mechanical and Chemical Engineering 2School of Civil and Resource Engineering CEED Client: Woodside Energy Ltd Abstract Pipeline stability design relies on an accurate prediction of the hydrodynamic forces induced by wave and current motion. The motion of wind generated waves is generally orbital, and the orbit paths flatten to an ellipsoid with depth. This leads to the assumption in deepwater that the vertical components of the wave motion tend to zero near the seabed. Due to this simplification wave motion is often modelled as rectilinear for the purposes of analysing on-bottom pipeline stability. This simplification predicts that the magnitudes of the hydrodynamic forces are equal on the forward and reverse half wave cycle. In computational fluid dynamics (CFD) modelling results have shown the drag force exerted on an on-bottom pipeline was 7% higher than expected on the forward half wave cycle, and 5% lower on the reverse half-wave cycle when waves were modelled as orbital rather than rectilinear. This paper describes CFD modelling to be conducted to investigate this phenomenon and verify the validity of this result. 1. Introduction Pipeline stability is an integral part of the offshore oil and gas industry and in particular is a major challenge for pipeline operators in the Australian North West Shelf (NWS). Due to the severity of the environmental conditions in the NWS, pipeline stabilisation can be a significant project cost, contributing up to 30% of the capital expenditure (Zeitoun et al.
    [Show full text]
  • Shedding Damage Detection of Metal Underwater Pipeline External Anticorrosive Coating by Ultrasonic Imaging Based on HOG + SVM
    Journal of Marine Science and Engineering Article Shedding Damage Detection of Metal Underwater Pipeline External Anticorrosive Coating by Ultrasonic Imaging Based on HOG + SVM Xiaobin Hong, Liuwei Huang , Shifeng Gong and Guoquan Xiao * School of Mechanical & Automotive Engineering, South China University of Technology, Guangzhou 510641, China; [email protected] (X.H.); [email protected] (L.H.); [email protected] (S.G.) * Correspondence: [email protected] Abstract: Underwater pipelines are the channels for oil transportation in the sea. In the course of pipeline operation, leakage accidents occur from time to time for natural and man-made reasons which result in economic losses and environmental pollution. To avoid economic losses and environ- mental pollution, damage detection of underwater pipelines must be carried out. In this paper, based on the histogram of oriented gradient (HOG) and support vector machine (SVM), a non-contact ultrasonic imaging method is proposed to detect the shedding damage of the metal underwater pipeline external anti-corrosion layer. Firstly, the principle of acoustic scattering characteristics for de- tecting the metal underwater pipelines is introduced. Following this, a HOG+SVM image-extracting algorithm is used to extract the pipeline area from the underwater ultrasonic image. According to the difference of mean gray value in the horizontal direction of the pipeline project area, the shedding Citation: Hong, X.; Huang, L.; Gong, damage parts are identified. Subsequently, taking the metal underwater pipelines with three layers S.; Xiao, G. Shedding Damage of polyethylene outer anti-corrosive coatings as the detection object, an Autonomous Surface Vehicle Detection of Metal Underwater (ASV) for underwater pipelines defect detection is developed to verify the detection effect of the Pipeline External Anticorrosive method.
    [Show full text]
  • DNV-OS-F101: Submarine Pipeline Systems
    OFFSHORE STANDARD DNV-OS-F101 SUBMARINE PIPELINE SYSTEMS 2000 DET NORSKE VERITAS Offshore Standard DNV-OS-F101, 2000 Contents – Page 3 CONTENTS Sec. 1 General................................................................. 10 D 900 Marine growth ................................................................ 23 A. General..................................................................................10 E. External and Internal Pipe Condition ...................................23 A 100 Introduction.....................................................................10 E 100 External operational conditions ...................................... 23 A 200 Objectives .......................................................................10 E 200 Internal installation conditions ....................................... 23 A 300 Scope and Application ....................................................10 E 300 Internal operational conditions ....................................... 23 A 400 Other codes .....................................................................10 F. Documentation......................................................................24 B. Normative References ..........................................................10 F 100 General............................................................................ 24 B 100 Offshore Service Specifications......................................10 F 200 Conceptual and detail engineering.................................. 24 B 200 Offshore Standards .........................................................10
    [Show full text]
  • Protection of Submarine Cables Through Spatial Separation
    DECEMBER 2014 WORKING GROUP 8 SUBMARINE CABLE ROUTING AND LANDING Final Report – Protection of Submarine Cables Through Spatial Separation The Communications Security, Reliability and Interoperability Council IV Working Group 8 Final Report 1: Spatial Separation December 2014 Table of Contents EXECUTIVE SUMMARY ........................................................................................ 1 BACKGROUND ON CSRIC IV AND WORKING GROUP 8............................ 14 Objectives and Methods ........................................................................................ 14 Membership .......................................................................................................... 15 BACKGROUND ON SUBMARINE CABLES AND THE FCC’S ROLE IN REGULATING THEM ............................................................................................ 17 Submarine Cables Are Critically Important to U.S. National Security and the U.S. Economy ............................................................................................................... 17 Scope and Elements of Submarine Cables............................................................ 19 Complex Federal Regulation ................................................................................ 21 3.3.1 The FCC Functions as the Primary Regulator of Submarine Cables Landing in the United States ......................................................... 21 3.3.2 Other Federal Regulation ........................................................................
    [Show full text]
  • 1 April 2011
    April 2011 UT3 The ONLINE magazine of the Society for Underwater Technology Offshore Engineering Tidal Energy Underwater Equipment 1 UT2 April 2011 Contents Processing Pilot Ready for Testing 4 April 2011 UT2 The magazine of the Offshore Jubarte, Wellstream 6, Gygrid, Tahiti, Gudrun, West Boreas 8, Society for Underwater Technology News Clov, Liuhua, Abkatun, FMC, Cameron/SLB 9, Deepwater Pipelay System 10, McDermott FEED, Brazil, Goliat, Ekofisk, Mariscal Sucre Dragon/Patao, BP 11, Ultra High Flow Injection, Omni- Choke 12 Underwater Flow Assurance Using Radioisotope Technology 14, Pipelines Deepwater Composite Riser 16, Hyperbaric Test Chamber Offshore Engineering Tidal Energy 17, High Pressure Swagelining, Plough in Baltic for Nord- Underwater Equipment Stream, SCAR 18 1 UT2 April 2011 The stern of Saipem’s new vessel showing the pipelay Underwater Subsea UK, RBG 20, Subspection, flexGuard 21, tower. Equipment Laser Scanning 22, HMS Audacious, TOGS, HULS, PAVS 24, Image: IHC Engineering Mojave in China 25, Tsunami Detection, Motion Sensor 26, Cable Survey 27, Cameras and Underwater Digital Stills 28, University of Plymouth Flora Lighting and Fauna Survey, True Lumens 30, Pan and Tilt Camera, April 2011 Aurora 31 Vol 6 No 1 Underwater Multi-Sensor AUV Pipeline Inspection, Integration 32, New Vehicles Markets for the AC-ROV 33, Cougar, CDS 34 2 Sonar 4000m Imaging, UUV, SALT 36, Sonar 294 37 UT Society for Underwater The Tide is Turning 36, MCT, Beluga 9 40, Bio Power 41, Technology Tidal 80 Coleman St The Bourne Alternative, Nexus Positioning, Hales Turbine 42, London EC2R 5BJ Norwegian Ocean Power 43, ORPC Turbine Generator 44, Oyster 2 45, Wave and Tidal 45 +44 (0) 1480 70007 Exhibitions UDT 46 Editor: John Howes [email protected] SUT Advanced Instrumentation for Research in Diving and Hyperbaric Medicine 47, AGM 48, Aberdeen Sub Editor: Michaelagh Shea [email protected] AGM and Dinner 49, AGM Perth 50 US: Published by UT2 Publishing Ltd for and on behalf of the Society for Underwater Stephen Loughlin Technology.
    [Show full text]
  • Shipping Databases, the Case of Lloyd's Register of Shipping
    City, University London Shipping Databases, the case of Lloyd’s Register of Shipping Petar nikolov January 2020 Submitted in partial fulfillment of the requirements for the degree of MSc or MA in Library Science Supervisor Dr. David Bawden Abstract This project is aimed at the Library and Information Science field, with the purpose of discussing industrial databases, more specifically shipping and shipbuilding databases. This project is focused mainly on the Lloyd’s Register of Shipping. We will start by discussing the historical basis which enabled the establishment of such a database, why it was created and what purpose it had in the field of shipping and what was the role it played in the shipbuilding industry. In this part we will look at the developments of the shipping from the medieval time to the time when the Lloyd’s Register was created by the London underwriters during 1760. From there we will pick up by looking at the early history of the register and why at the end of the eighteenth century a rival register was created by the shipowners. We also look how the two registers slowly began to decline and how finally they reformed themselves into the current register in the year of 1834. The next part of the project will be concerned with the nineteenth century shipbuilding developments and how the Lloyd’s Register responded to them. We will look at the transition from wood to iron and then from iron to steel. In both cases the Lloyd’s Register of Shipping developed sets of rules to govern how ships of iron and steel should be built, alongside the rules it has established for building of wooden vessels.
    [Show full text]
  • Stability of Offshore Pipelines in Close Proximity to the Seabed
    6th Pipeline Technology Conference 2011 Stability of Offshore Pipelines in Close Proximity to the Seabed F. Van den Abeele and J. Vande Voorde ArcelorMittal Global R&D Gent (OCAS N.V.) J.F. Kennedylaan 3, BE-9060 Zelzate, Belgium ABSTRACT In traditional offshore pipeline design, the on-bottom stability of submarine pipelines is governed by the Morrison’s equations. According to this set of equations, offshore pipelines are designed to satisfy two stability conditions: the submerged weight of the pipe has to be greater than the lift force, and the horizontal frictional force should exceed the combined drag and inertia forces. It is common practice to used fixed hydrodynamic coefficients (drag, lift and inertia) to calculate the pipe stability, based on the assumption that the pipeline is either trenched or in contact with the seabed. However, due to uneven seabed topology and/or scouring, a gap may exist between the pipe and the seafloor. In such a case, the force coefficients not only depend on the relative gap between the pipe and the seabed. Moreover, in unsteady oscillatory flow (induced by waves), the time- dependent laminar or turbulent characteristics of the boundary layer become important. In this paper, a computational fluid dynamics (CFD) model is presented to study on- bottom stability of offshore pipelines in close proximity to the seabed. Numerical simulations of fluid flow are performed to evaluate the lift, drag and inertia forces exerted on a subsea pipeline when subjected to both steady current (tides) and oscillatory flow (waves). The evolution of the hydrodynamic coefficients with the relative gap between the pipe and the seafloor is investigated, and the effect of boundary proximity on the stability is revealed.
    [Show full text]
  • Numerical Study of the Influence of Tidal Current on Submarine Pipeline Based on the SIFOM–FVCOM Coupling Model
    water Article Numerical Study of the Influence of Tidal Current on Submarine Pipeline Based on the SIFOM–FVCOM Coupling Model Enjin Zhao 1,2 , Lin Mu 1,2,* and Bing Shi 3 1 College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China; [email protected] 2 Shenzhen Research Institute, China University of Geosciences, Shenzhen 518057, China 3 College of Engineering, Ocean University of China, Qingdao 266100, China; [email protected] * Correspondence: [email protected] Received: 29 October 2018; Accepted: 6 December 2018; Published: 10 December 2018 Abstract: The interaction between coastal ocean flows and the submarine pipeline involved with distinct physical phenomena occurring at a vast range of spatial and temporal scales has always been an important research subject. In this article, the hydrodynamic forces on the submarine pipeline and the characteristics of tidal flows around the pipeline are studied depending on a high-fidelity multi-physics modeling system (SIFOM–FVCOM), which is an integration of the Solver for Incompressible Flow on the Overset Meshes (SIFOM) and the Finite Volume Coastal Ocean Model (FVCOM). The interactions between coastal ocean flows and the submarine pipeline are numerically simulated in a channel flume, the results of which show that the hydrodynamic forces on the pipeline increase with the increase of tidal amplitude and the decrease of water depth. Additionally, when scour happens under the pipeline, the numerical simulation of the suspended pipeline is also carried out, showing that the maximum horizontal hydrodynamic forces on the pipeline reduce and the vertical hydrodynamic forces grow with the increase of the scour depth.
    [Show full text]
  • Environmental Impact Assessment Report the Proposed Construction and Operation of a Subsea Fuel Pipeline and Offshore Mooring S
    ENVIRONMENTAL IMPACT ASSESSMENT REPORT THE PROPOSED CONSTRUCTION AND OPERATION OF A SUBSEA FUEL PIPELINE AND OFFSHORE MOORING SYSTEM FOR THE DISCHARGE OF PETROLEUM PRODUCTS AT RAROTONGA, COOK ISLANDS JULY 2016 1 TABLE OF CONTENTS PART A: Information on Environmental Impact Assessment [EIA] Preparation 1. Introduction 2. EIA Objectives 3. Stakeholder Consultation 4. EIA Format PART B : Environmental Impact Assessment EXECUTIVE SUMMARY GLOSSARY OF TERMS 1. INTRODUCTION 1.1 Proposal Proponent 1.2 Proposal Description 1.3 Proposal Objectives and Scope 1.4 Environmental Impact Assessment Process 1.4.1 EIA Methodology 1.4.2 EIA Objectives 1.4.3 Submissions 1.5 Public Consultation Process 1.5.1 Relevant Legislation and Policy Requirements 1.5.2 Planning Process and Standards 2. Proposal Need and Alternative 2.1 Proposal Justification 2.2 Alternatives to the Proposal 3. Description of the Proposal Development 3.1 Location 3.2 Staging 3.3 Emergency Management 3.4 Infrastructure Requirement 3.4.1 Transport 3.4.2 Energy 3.4.3 Water Supply and Storage 3.4.4 Storm Water Drainage 3.5 Waste Management 3.5.1 Character and Quantities of Waste Materials 3.5.2 Solid Waste Disposal 4. Environmental Values and Management of Impacts 4.1 Land 4.1.1 Description of Environment Values 4.1.1.1 Soils 4.1.1.2 Land use Characteristics 4.1.1.3 Landscape Character 4.1.2 Potential Impacts and Mitigation Measures 4.1.2.1 Land use Suitability 2 4.1.2.2 Land Contamination 4.1.2.3 Soil Erosion 4.2 Climate 4.3 Water Resources 4.3.1 Description of Environmental Values 4.3.2
    [Show full text]