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Showing papers on "Submarine pipeline published in 1987"


Journal ArticleDOI
TL;DR: In this paper, a more rational interpretation of submarine pipeline vertical buckling behavior is presented, which provides additional insight into the mechanism of the ‘pop-up’ phenomenon and enables quantitative definition of both the respective critical state and the immediate post-buckling characteristics for the first time.

41 citations


Journal ArticleDOI
01 Jan 1987
TL;DR: In this article, the authors reviewed the physical oceanographic characteristics of the Bristol Channel and Severn Estuary, including the general pattern of water movement and the influence of high freshwater discharges on the salinity distribution.
Abstract: Investigations into the physical oceanographic characteristics of the Bristol Channel and Severn Estuary are reviewed; these include the general pattern of water movement and the influence of high freshwater discharges on the salinity distribution. Various approaches to the problem of defining sediment transport paths in the macrotidal estuarine system, for fine grained and coarse grained material, are summarised. Transport patterns are examined, for example, through: the distribution of surficial sediments and their associated bedforms; seabed drifter studies; the analysis of tidal current and wave data, separately and in combination, because of their influence on bedload transport paths; satellite imagery, within the visible part of the spectrum; and on the basis of output from depth-averaged numerical models. Comparison between the interpretations shows that there are discrepancies and contradictions in the derived sediment transport paths. In particular, it is difficult to explain the up-channel movement of fine grained material against a background of inferred offshore movement, shown by the orientation of sandwaves and the direction of movement of the surface waters. An early model to overcome this contradiction incorporated ‘two-way differential transport’ throughout the water column. Localised contradictions in the transport paths for sand and ‘fine sediment’ occur in the inner part of the Bristol Channel. The most recent conjectural models for sediment movement incorporate an ebb- dominated zone along the central axis of the Channel, together with flood-dominated coastal zones. This lateral variation in transport paths, across the Channel, constrasts with the earlier proposition for vertical differentiation; it is suggested by seabed drifter recovery patterns and confirmed by the output from one of the numerical models. Transport towards the flood-dominated zones at the boundaries is enhanced under the superimposed influence of waves, which is demonstrated through the use of sediment transport formulae and sand tracer experiments. Although the annual contribution of the rivers to the overall sediment budget is shown to be small, the time of retention of waters and sediment within the system could result in fluviatile sediment inputs being retained for tens of years. In an attempt to extrapolate observations of transport processes into the ancient record, a preliminary facies model for the macrotidal Bristol Channel is presented. The model shows the availability of sand increasing in an onshore direction; progressing in this direction, the facies pass from scoured bedrock and lag deposits, through cross bedded megaripple foresets and the topset planar bedding of intertidal flats, to Holocene fill and supratidal deposits.

31 citations


Proceedings ArticleDOI
01 Jan 1987

21 citations


Journal ArticleDOI
TL;DR: In this article, the authors introduce the coastal margin as a source or sink for sediment in the marine environment and present a perspective on this issue by considering the situation in a parallel discipline.
Abstract: This contribution serves as an introduction to the ‘Coastal Margins as Sediment Traps’ thematic set. One of the most basic questions which faces those concerned with sediment transport in the marine environment is whether the coastal margin is a net source or sink for sediment. The coastal margin is taken to mean the coast itself with its cliffs, bays and estuaries, and the immediate coastal zone stretching a few hundred metres to a few kilometres off shore. It is not clear to what extent the coasts of NW Europe have recovered from the last period of depressed sea level. Uncertainty exists as to whether sediment lost from the coastal margin is deposited in offshore sinks, whether sediment originally laid down on the continental shelves is returning to depositional sites located principally in bays and estuaries, or more particularly whether all coastal margins are subject to the same balance of processes. The reason for this lack of knowledge is clear. The calculation of the sediment budget of an estuary is difficult. The calculation of the budget for a whole coastal sector, including the continental shelf fronting it, is even more problematical. For entire seas our capacity for reliable quantification at the present time is negligible. A perspective on this issue can be obtained by considering the situation in a parallel discipline. Oceanographers have been studying the circulation of our shallow seas for 70–80 years, latterly with co-operative experiments using tens of simultaneously deployed, self-recording, current meters and the mathematical models

20 citations


09 Jun 1987
TL;DR: In this paper, the authors evaluated the stability of an offshore pipeline from a geotechnical point of view and concluded that self-burial of a pipeline is possible using morphological aspects of potential selfburial together with a study into the forces induced by dynamic fluid pressures.
Abstract: The final objective was to evaluate the stability of an offshore pipeline from a geotechnical point of view. On the Dutch part of the Continental Shelf pipelines are used for the transportation of oil and gas and utilities liRe glycol. The mean waterdepth on this part of the North Sea varies from 20-40 meters. As this region is a major fishing area while in some places the pipelines cross the shipping lanes the authorities demand that pipelines are buried to a depth of 1.00 m below the surface of the seabed. In view of the high costs of the burying operation and because of some reported cases of instability an evaluation of the possibility of instability seems relevant. In some cases regulations were released to lay pipelines unprotected on top of the seabed. In these cases it was supposed that the pipeline would be buried by natural processes. After installation the behaviour of these pipelines was monitored. Although this method was not successful in all cases it could be concluded that self-burial of a pipeline is possible. The morphological aspects of potential self-burial together with a study into the forces induced by the dynamic fluid pressures have been studied in separate projects.

16 citations


Journal ArticleDOI
TL;DR: In this paper, a smooth submarine pipeline, fixed horizontally near a plane boundary, has been investigated under random wave conditions, and the inline hydrodynamic coefficients of drag and inertia were evaluated using two different methods, one in the frequency domain and the other in the time domain.

13 citations


Proceedings ArticleDOI
01 Jan 1987
TL;DR: The PIPESTAB project as mentioned in this paper investigated the major physical phenomena involved in predicting the lateral stability of untrenched pipelines on the ocean floor and developed a set of non-dimensional curves that characterised the motions and strains of pipelines.
Abstract: A comprehensive research programme has been carried out to investigate the major physical phenomena involved in predicting the lateral stability of untrenched pipelines on the ocean floor. This project, the Pileline Stability Design (PIPESTAB) Project, included both analytical and experimental investigations aimed at developing a technically sound basis for on-bottom stability design of submarine pipelines. From these experimental studies analytical models have been developed for the prediction of hydrodynamic and soil resistance forces acting on the pipeline. These models have been included in a response model program capable of predicting the time history of movement and strain in the pipe. From these predictions has been developed a set of non-dimensional curves that characterise the motions and strains of pipelines. These results resolve to a large extent the apparent conflict between measured hydrodynamic forces and the lack of observed pipeline stability failures using present design methods. See next two Abstracts.

12 citations


Journal ArticleDOI
F. G. Larminie1
TL;DR: The history of the development of the hydrocarbon resources of the North Sea is reviewed in an environmental context in this paper, with reference to platforms, subsea pipelines, pipeline landfalls and terminal construction and operation.
Abstract: The history of the development of the hydrocarbon resources of the North Sea is reviewed in an environmental context. The development of impact assessment techniques and practices and the evolution of monitoring of the physical, chemical and biological environment offshore and onshore, with reference to platforms, subsea pipelines, pipeline landfalls and terminal construction and operation is discussed. A brief account of the development of environmental protection management practices and their application to the design, construction, operation and management of major production projects follows. The paper concludes with a look at the environmental conditions likely to be established as the industry moves into the northern North Sea and areas such as the West Shetland Basin, and their significance for the petroleum industry.

9 citations


Proceedings ArticleDOI
01 Jan 1987
TL;DR: In this article, a combination of beam-trawl impact tests and pull-over calculations is used to determine pipeline integrity during trawl-gear crossings, but includes some conservative elements.
Abstract: It is concluded in this paper that the present approach of a combination of impact tests and pull-over calculations is very useful in determining pipeline integrity during trawl-gear crossings, but includes some conservative elements. It is suggested that this conservatism may be reduced by devising more realistic beam-trawl impact tests and a more accurate description of pipe/seabed interaction for pull-over calculations. This will be of special interest for evaluating during trawl-gear crossings of small diameter pipelines.

8 citations


Proceedings ArticleDOI
K. Holthe1, T. Sotberg1, J.C. Chao2
01 Jan 1987
TL;DR: In this article, an efficient computer program for predicting the dynamic response (movement and stress) of submarine pipelines to storm waves and current has been developed, where the pipeline is assumed initially straight, is moving on a horizontal plane (bottom) and is exposed to loading from waves and currents.
Abstract: An efficient computer program for predicting the dynamic response (movement and stress) of submarine pipelines to storm waves and current has been developed. The pipeline is assumed initially straight, is moving on a horizontal plane (bottom) and is exposed to loading from waves and current. The structural response is based on small displacement theory. The increase in the axial force in the pipe due to bending deformation is included. Simulations of the dynamic response are presented in computer plots. Typical results are given for both single element (pipeline section) systems and long pipes, simple and history dependent soil models for sand and clay, and regular and irregular sea states.

6 citations




Patent
05 Jun 1987
TL;DR: In this paper, the authors proposed a method for weighting down a pipeline buried in a trench to adjust the descent and inflection of the pipeline, which was applied to offshore worksites.
Abstract: The invention relates to weighting down a pipeline buried in a trench. As the means 12 for cutting a trench 2 move forward, a weighting-down trolley 10 is driven which pushes on the pipeline 3 resting on a casing 5 which is flexible and deformable and filled with liquid and whose pressure is adjusted by means 20, 21 for adjusting the descent and inflection of the pipeline. Application to burying pipes on "offshore" worksites.

Patent
07 Aug 1987
TL;DR: The Disclosure Disclosed as mentioned in this paper is an apparatus for simultaneously trenching and laying a submarine pipeline within the bed of a body of water covered with a relatively thick ice mass, which consists of a pipeline construction spread which precedes a pipe installation spread, both of which traverse the ice mass.
Abstract: of the Disclosure Disclosed is an apparatus for simultaneously trenching and laying a submarine pipeline within the bed of a body of water covered with a relatively thick ice mass. The apparatus comprises a pipeline construction spread which precedes a trenching and pipe installation spread, both of which traverse the ice mass. The pipe installation vehicle advances toward the constructed pipeline, elevates the pipeline, forms a slot-like opening in the ice and directs the pipeline into the water through the slot. A submersible dredging assembly extends from a installation vehicle which forms part of the installation spread. As the vehicle advances, the dredging assembly forms a trench in the sea bed. At the same time the dredging assembly guides the pipeline into the trench and provides support to a submerged component of the pipeline which is threaded through a slot in the dredging assembly.

Patent
31 Oct 1987
TL;DR: In this article, a single mooring/seabed oil house is used for the oil storage of offshore oil fields, and an anchor chain support pontoon is arranged to enhance the intensity of the anchor chain and the oil pipeline.
Abstract: The utility model discloses a single mooring/seabed oil house used for the oil storage of offshore oil fields. The device of the utility model comprises a seabed oil house, an anchor chain support pontoon and a single mooring device. The seabed oil house is an oil storage device which is made from reinforced concrete and is provided with two layers of bulkheads. The single mooring device which is an iron pontoon acts a part in controlling and mooring. The seabed oil house and the single mooring device are connected by an anchor chain and an oil pipeline. An anchor chain support pontoon is arranged to enhance the intensity of the anchor chain and the oil pipeline.

01 Jan 1987
TL;DR: The Black Rock Ocean Outfall Pipeline as discussed by the authors was constructed by the Geelong and District Water Board to replace an existing shoreline discharge which was first commissioned in 1916 and discharges 1.2 km offshore from Black Rock into 15 metres depth of water providing a minimum initial dilution of 50:1.
Abstract: The Black Rock Ocean Outfall Pipeline has been constructed by the Geelong and District Water Board to replace an existing shoreline discharge which was first commissioned in 1916. Together with an onshore screening plant the outfall pipeline will provide disposal facilities to handle domestic and industrial wastewater from the Geelong area and a number of smaller communities on the Bellarine Peninsula, and the town of Torquay. The Outfall has been designed to handle flows up to the year 2040 and discharges 1.2 km offshore from Black Rock into 15 metres depth of water providing a minimum initial dilution of 50:1. A cement mortar lined steel pipe has been used with an external corrosion protection of fusion bonded polythylene. A bottom tow technique was used for installation of the outfall with the required negative buoyancy being provided by 120 ram thickness of concrete weight coating. The outfall was prefabricated in a single length before commencement of the! tow to reduce the required towing time. Long term stability of the outfall is provided using backfilling and rock armour.

Journal Article
TL;DR: The Q-8 field was commissioned in October of last year by BP International plc for its partners, DSM Aardgas and Chevron Oil Co. as discussed by the authors, and the final cost for the complete development of platform, offshore pipeline and landfall, onshore pipeline, and gas-processing terminal was $50 million.
Abstract: Integral to BP International's Q/8 gasfield development in the Dutch sector of the North Sea was a two-phase gas export pipeline laid in shallow water to shore. This site required construction of a directionally drilled landfall in an environmentally sensitive area. The Q-8 field was commissioned in October of last year by BP International plc for its partners, DSM Aardgas and Chevron Oil Co. The field's low in-place reserves precluded a conventional North Sea development as uneconomic. Thus a fast-track, minimum-facilities approach was adopted. The project was completed within time and budget. The final cost for the complete development of platform, offshore pipeline and landfall, onshore pipeline, and gas-processing terminal was $50 million. All construction contracts for these works were completed within 12 months of letting.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the effectiveness of three types of stabilization techniques, Anchoring the pipeline, increasing the weight of the pipeline and new stabilization technique which has been proposed by the authors.
Abstract: Designing a offshore pipeline for installation in an area subjected to earthquake activity requires an investigation of potential effects of seismic shocks. If the seabed or the filling material along a pipeline route consists of cohesionless soils likely to liquefy under the influence of seismic shocks, a pipeline buried in such soils may lose stability and float to the surface of the seabed. This paper describes the effectiveness of three types of stabilization techniques, 1) Anchoring the pipeline, 2) Increasing the weight of the pipeline, and 3) New stabilization technique which has been proposed by the authors. In order to simulate the behavior of pipeline under liquefaction, we used finite element model which was proposed by Minami, Kiyomiya and Tsuchida.

01 Jan 1987
TL;DR: Esso Australia continues to use the bottom tow technique to reduce the cost of installing submarine pipelines in Bass Strait as discussed by the authors, and the first 650 metres of the Bream pipeline is described in detail including onshore fabrication, bottom tow along the seabed to site and connection to a preinstalled riser at the bream offshore production platform.
Abstract: Esso Australia continues to use the bottom tow technique to reduce the cost of installing submarine pipelines in Bass Strait. Other installation techniques are described for comparison. The installation of the first 650 metres of the Bream pipeline is described in detail including onshore fabrication, bottom tow along the seabed to site and connection to a preinstalled riser at the Bream offshore production platform. Areas of cost saving are identified and the potential use of the technique for the installation of future pipelines is discussed.

Journal ArticleDOI
TL;DR: In this paper, a discussion is made on a new oil transporting system using magnetic coaxial pipe concerning its electrical characteristics and the experimental resuslts on a 150m length test pipeline.
Abstract: A discussion is made on a new oil transporting system using magnetic coaxial pipe concerning its electrical characteristics and the experimental resuslts on a 150m length test pipeline. When magnetic coaxial pipe is used as a heater, the heat generation occurs uniformly and the voltage of the outside of the coaxial pipe is sufficiently low to be electrically safe even when the frequency is low. This system is applicable to long distance submarine pipelines.

Journal ArticleDOI
TL;DR: In this paper, the authors describe how existing geological knowledge combined with geophysical measurements and exploratory oil well data have given a surprisingly large amount of information regarding ground conditions where the "geology" is hidden by deep water.

Journal ArticleDOI
TL;DR: In this article, a nonlinear mathematical model for predicting stresses in a submarine pipeline as it is picked up off the ocean floor by barge davits for purposes such as repairs and tie-ins is presented.