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Showing papers on "Submarine pipeline published in 1988"


Journal ArticleDOI
TL;DR: In this paper, the earthquake is considered as a partially correlated stationary random process characterized by a power spectral density function (PSDF), and the cross-spectral density function between two random inputs along the length of the pipe is defined with the help of the local earthquake PSDF, which is the same for all points, and a frequency-dependent, exponentially decaying function (with distance).
Abstract: Submarine pipelines are many a time buried into a jet-blasted channel in the seabed. Seismic response of such buried pipelines are investigated in this paper. The earthquake is considered as a partially correlated stationary random proceeds characterized by a power spectral density function (PSDF). The cross-spectral density function between two random inputs along the length of the pipe is defined with the help of the local earthquake PSDF, which is the same for all points, and a frequency-dependent, exponentially decaying function (with distance). A lumped-mass model with 2-D beam elements is used to write the equation of motion. Soil resistance to dynamic excitation along the pipe length is obtained in an approximate manner with the help of frequency-independent impedance functions derived from half-space analysis and Mindlin's static stresses within the soil due to point loads. The responses are obtained by a spectral analysis for horizontal ground motions in two principal directions, which are assumed to coincide with pipe axis and the perpendicular to it. Using the proposed method of analysis, a parametric study is conducted. The results of the study help in understanding the behavior of buried submarine pipelines under seismic forces and its differences from that of the buriedmore » pipelines on land.« less

22 citations


Journal ArticleDOI
TL;DR: In this article, a series of model tests were carried out to understand the intensity of the drag force brought about by a mudflow on a cylindrical solid column, and an empirical equation was proposed to predict the magnitude of the force exerted by a flow of clay slurry.

15 citations


Journal ArticleDOI
TL;DR: In this article, a magnetometric off-shore electrical sounding (MOSES) was used to map the electrical properties of the sea floor in Aretic regions, a particular target is the permafrost layer under the Beaufort Sea.
Abstract: A novel variation of the geophysical technique known as MOSES, for Magnetometric Off-Shore Electrical Sounding, has been developed to map the electrical properties of the sea floor in Aretic regions. The particular target is the permafrost layer under the Beaufort Sea, a layer containing frozen or partially frozen sediment from 100 to 600 m thick underlying shallow sea water, typically 10 to 100 m deep, and several tens of metres of soft sediment. A detailed knowledge of the location and physical properties of the permafrost layer is essential for accurate interpretation of reflection seismic data. The permafrost can contain pockets, regions or layers of gas hydrate. The latter is both a possible resource and a hazard to drilling operations or hydrocarbon production. A local map of the permafrost zone is essential geotechnical information required prior to the construction of an offshore structure or pipeline.

14 citations


Journal ArticleDOI
TL;DR: In this paper, detailed physical oceanographic and sedimentological data, collected from a coastal embayment and adjoining inner continental shelf, are used to exemplify the changes in sediment transport vectors which take place when wave action is superimposed upon that of tidal currents.

11 citations


Journal Article
TL;DR: In this paper, the authors focus on the fundamental points of design for subsea pipeline installation in certain regions of the world often implies crossing several existing pipelines or cables in operation, and careful attention to such contingencies can ensure a safe and a cost-effective installation.
Abstract: Designing for subsea pipeline installation in certain regions of the world often implies crossing several existing pipelines or cables in operation. Careful attention to such contingencies can ensure a safe and a cost-effective installation. Economical and safe design of submarine pipeline crossings varies with the environmental conditions, pipeline characteristics, and construction means. The purpose here is to focus on the fundamental points of design.

5 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined design and operational considerations in determining the significance of unsupported offshore pipeline spans that may develop during pipeline installation or field operation, while applying original design criteria is likely to result in cost-prohibitive repair predictions.
Abstract: Design and operational considerations have been examined in determining the significance of unsupported offshore pipeline spans that may develop during pipeline installation or field operation. Allowable unsupported span lengths determined during design are generally based on strict code compliance and a design foundation encompassing the worst possible environmental and operational loads. During operation, however, unsupported spans develop beyond the allowable limits, perhaps as a result of various unforseen local conditions. Applying original design criteria is likely to result in cost-prohibitive repair predictions, while lack of action may result in loss of production. Without the design code requirements of an existing or a proposed pipeline system being violated, realistically safe design can be approached through evaluation of the sensitivity of the key design parameters. Priorities for remedial repair of the unsupported spans can be established for the pipelines in service while operating constraints, budget, and schedule are recognized. On the basis of periodic surveys, properly formatted survey data, and reanalysis of the design parameters, pipeline span repair cost estimates and schedules can be appreciably reduced. Similar principles can be applied to a pipeline in planning and design stages to ensure a safe operating design and to eliminate an uneconomically conservative design.more » These design and operational considerations are illustrated through a case study.« less

4 citations


Journal Article
TL;DR: In this paper, site-acceptance tests for a recently installed leak-detection system on a pipeline in southern Alberta indicated that the system will reduce spillage because of leaks.
Abstract: Site-acceptance tests for a recently installed leak-detection system on a pipeline in southern Alberta indicated that the system will reduce spillage because of leaks. The tests on the Porcupine Hills Pipeline also indicated that pipeline isolation and spill containment are enhanced by the use of the system. Covered here are the selection, design, and implementation of the real time leak-detection system and its extension to offshore and arctic applications.

4 citations


Journal Article
TL;DR: In this article, a pipeline economics report includes information on the following topics: U.S. interstate pipeline mileage, current pipeline costs, investment in liquids pipelines, 10-year construction cost trend, current compressor station costs, completed compressor-station costs, top 10 interstate liquids pipelines; natural gas transmission expenses; top 10 gas pipelines; onshore pipeline projects; offshore pipeline projects, compressor facilities; liquids pipeline companies; and gas pipeline companies.
Abstract: This pipeline economics report includes information on the following topics: U.S. interstate pipeline mileage; current pipeline costs; investment in liquids pipelines; 10-year construction cost trend; current compressor station costs; completed compressor-station costs; top 10 interstate liquids pipelines; natural-gas transmission expenses; top 10 interstate gas pipelines; onshore pipeline projects; offshore pipeline projects; compressor facilities; liquids pipeline companies; and gas pipeline companies.

4 citations


Proceedings ArticleDOI
01 Jan 1988
TL;DR: In this paper, the authors describe the equipment and procedures used to completely remove these solids from the line, with particular reference to the unique risks and difficulties associated with offshore pipelines, and present the results of their experiments.
Abstract: Severe wax deposits had built up in the Valhall subsea crude oil pipeline over a period of years. The equipment and procedures used to completely remove these solids from the line are described, with particular reference to the unique risks and difficulties associated with offshore pipelines.

3 citations


01 Apr 1988
TL;DR: In this article, a configuration pipe with a spoiler induces a radical change in the flow around the pipeline, and the effects occur in both the morphological and hydrodynamic sense, in order to prevent offshore submarine pipelines from damage by fishing gear and excessive wave and current forces.
Abstract: To prevent offshore submarine pipelines from damage by fishing gear, the formation of dangerous free-spans and excessive wave and current forces, it is a requirement that these pipelines are completely buried under the seabed. Usually pipelines are buried artificially by means of ploughing, digging or jetting in order to meet the requirements of authorities of a minimum cover of about one meter (Dutch government). A spoiler is a plastic fin which is attached in the longitudinal direction on top of the pipeline. Relative to a plain pipe the configuration pipe with spoiler induces a radical change in the flow around the pipeline. The effects are twofold: changes occur in both the morphological and the hydrodynamic sense.

3 citations



Book ChapterDOI
01 Jan 1988
TL;DR: In this article, the authors describe an ongoing research program for modelling offshore pipeline failures using a technique known as discriminant analysis, which can be used to forecast the likelihood of a pipeline failing and the probability of that occurrence.
Abstract: This paper describes an ongoing research programme for modelling offshore pipeline failures using a technique known as ‘Discriminant Analysis’. Using data from the North Sea, this paper shows how this technique can be employed to forecast the likelihood of a pipeline failing and the probability of that occurrence. It is thought that this methodology has potential for more cost effective design and operation of pipelines taken singly and in networks throughout their life cycles.

Proceedings ArticleDOI
M.R. Saad1, B. Singh1
01 Jan 1988
TL;DR: In this article, the handling of liquids in the multi-phase flow pipeline system within Carigali's Duyong Offshore Gas Complex and the Onshore Gas Terminal, in Kerteh, Terongganu, is discussed.
Abstract: This paper deals with the handling of liquids in the multi-phase flow pipeline system within Carigali's Duyong Offshore Gas Complex and the Onshore Gas Terminal, in Kerteh, Terongganu. The data and operations experience gathered necessitate changes to the operating procedures originally identified during the design phase. This is to ensure more efficient handling of liquid hold-up in the pipeline during low gas flowrates.

Journal Article
TL;DR: In this paper, the authors analyzed the choice between pipeline alternatives and coastal shipping in a benefit-cost framework, and concluded that the pipeline alternative is most feasible in the case of the Cameroon.
Abstract: Petroleum product shipments from refinery to centers of consumption frequently involve a choice of transportation modes. This is particularly the case where a refinery is situated in a relatively isolated coastal area close to offshore oil deposits, as in the Cameroon. This paper analyses the choice between pipeline alternatives and coastal shipping in a benefit-cost framework, and concludes that the pipeline alternative is most feasible in the case of the Cameroon. The extension of the analysis to other countries is also discussed with respect to five parameters that could vary from the Cameroon case: distance, topology, uncertainty, secondary benefits and port investments. The paper concludes that for distances under 150 km, the pipeline alternative enjoys a distinct advantage, and in most cases there is an advantage over even greater distances.


Journal ArticleDOI
TL;DR: In this article, the authors reviewed the methods currently available for submarine pipeline repairs, and some future developments in the field of submarine pipeline repair are briefly outlined, and the emergency pipeline repair services available are described.
Abstract: The failures of submarine pipelines in the North Sea, and the response of pipeline operators are first discussed. Against this background, the methods currently available for submarine pipeline repairs are reviewed. The Emergency Pipeline Repair Services available are described, and some future developments in the field of submarine pipeline repair are briefly outlined.


Journal ArticleDOI
TL;DR: In this paper, an analytical solution for the dynamic response of soil layers appearing in the offshore seabed is presented. But the results of PS-logging performed at the boring site of the Senshu-oki Seabed in Osaka Bay as deep as 150m are not available.
Abstract: Recently, some big reclamation projects are being pursued in offshore areas where the water depth is far beyond ten meters and there exist clay-rich soil layers whose overconsolidation ratios are not so far from unity. The present note deals with an analytical solution for the dynamic response of soil layers appearing in the offshore seabed. Referring to the result of PS-logging performed at the boring site of Senshu-oki seabed in Osaka Bay as deep as 150m, it is found that there exists a relationship between the celerity of transversal wave, vs (m/s), and the depth of soil layers, z (m), as vs=30z0.5. Another informations obtained from the soil exploration also indicate that the seabed is almost normally consolidated at this site. The characteristic solution and the procedure of dynamic response analysis in such soil layers are deduced by solving the fundamental differential equation.

Journal ArticleDOI
TL;DR: An overview of the important technical issues that need to be considered to ensure safe design, installation, and operation of pipelines for North Sea service is presented in this paper, where the authors also discuss the impact of pipeline integrity on offshore operations.
Abstract: Pipelines in some form or other are the essential link between offshore oil and gas production facilities and the onshore users. Be they seabed, seabed trenched, interfield, onshore transport, or transport to offshore loading facilities, all operations are dependent on the effectiveness and integrity of the transmission pipeline. Fifteen years experience in the North Sea has seen in excess of 150 subsea oil and gas pipelines installed in the UK sector extending for a total length exceeding 4000 km. At the time of writing, no hazard or incident has arisen from these installations. An overview of the important technical issues that need to be considered to ensure safe design, installation, and operation of pipelines for North Sea service is presented.MST/632