/pdf/effects-of-offshore-oil-and-gas-development-a-current-hqh1vmgq95.pdf

Effects of Offshore Oil and Gas Development: A Current Awareness Bibliography

Nowadays, the standard techniques of backing the ballasted pipeline laid in a bottom trench are used: sequential deposition of soil by suction dredges along the slurry pipeline, soil discharge by self-dumping barges, soil unloading from a barge by the grapple, soil pumping from barges. The disadvantage of these methods is that backfill is done in consecutive stages, and soil, falling into water increases water specific weight to the pulp specific weight. As a result, the buoyancy force increases and, when backfill is accomplished, the pipeline is raised above the design reference mark. The aim of the research is to optimize the existing methods of pipelines backfill, which will prevent or reduce the rise of the pipeline from the design position during its backfill. The optimized methods of the submerged pipelines backfill, which use temporal metal and reinforced concrete loads or backfill by cofferdams, have been calculated with the help of APMWinMachine software. The results of the model calculation by the method of finite elements show the effectiveness of the proposed methods of the submerged pipeline backfill. Аннотация. Сегодня засыпка уложенного в подводную траншею забалластированного трубопровода производится стандартными способами: последовательное рефулирование грунта земснарядами по пульпопроводу, сброс грунта саморазгружающимися шаландами, сброс грунта из барж путем выгрузки его грейфером, перекачивание грунта из барж. Недостатком данных методов засыпки подводного трубопровода является то, что засыпка ведется последовательно, а грунт, попадая в воду, вызывает увеличение удельного веса воды до удельного веса пульпы. Вследствие этого возрастает выталкивающая сила, под действием которой трубопровод поднимается, и после завершения засыпки оказывается выше проектной отметки. Целью работы является оптимизация существующих способов засыпки подводных трубопроводов, которая предотвратит или снизит выход трубопровода из проектного положения при его засыпке. С помощью пакета инженерных программ APMWinMachine рассмотрены и рассчитаны оптимизированные способы засыпки подводных трубопроводов, которые заключаются в использовании временных металлических или железобетонных пригрузов или засыпке трубопровода перемычками. Результаты расчетов моделей методом конечных элементов показывают эффективность предложенных способов засыпки. Introduction In the pipe conduit construction of submerged crossing, the problem of subaqueous pipelines escapement from the design position during the construction is commonly encountered, and, particularly, during the backfill of the trench ballasted pipelines laid in the bottom. This problem is commonly encountered in subsea pipelines construction by the trench method implemented by the public corporations such as joint stock company Podvodtruboprovodstroy (submerged crossing across the river Ob on the oil pipeline Surgut-Perm, submerged crossing across the river Ishim on the gas pipeline Ostrogozhsk-Belousovo, and others), public corporation “Mezhregiontruboprovodstroy” (submerged

Calculation of optimized methods of the river underwater pipeline backfill with the use of APMWinMachine 9.7

In this study, a protection-pipe system has been developed for the protection of undersea electricity cable layout along shoreline with medium deep water. The protection pipes are made of cast-iron alloys while the dimensions are designed corresponding to the balk diameter of electricity cables. The water depth of the area with cable layout is ranged from several meters to a hundred meters, where berthing anchoring from commercial ships and towing operation from fishing boats are constantly found. Therefore, to make sure that the protection pipe can work dependably against the loadings mainly from the operation as was mentioned, both analytical analysis and experimental tests were carried out. In the experimental studies, the full-scale model of several sets of protection-pipe system was tested for impact loadings. It was found from the results of both the analysis and experimental tests that the protection-pipes are able to meet the requirements of the local power company TPC set for the cable layout under seawater.

Performance of a Covering Pipe for the Protection of Underwater Cable Subjected to on-Site Impact Loadings

In this study, a protection-pipe system is developed for the protection of undersea electricity power cable laid along shoreline with medium deep water. The protection-pipes are made from ductile cast-iron alloys while the dimensions are designed corresponding to the diameter of balk electricity power cables. In order to know if the protection-pipe is strong enough to prevent the power cable from damages caused unnaturally, such as berthing anchoring from large size ships or towing operation from fishing boats, both analytical and experimental studies were carried out. Presented in this paper is an analytical study based on the material mechanics. A finite element analytical method was applied and the deformed shapes on the protection-pipe were studied. Along with the deformation, the corresponding stresses were also presented. In order to know the response of the protection-pipe subjected to an impact loading exerting on various parts of the pipe, several analysis for various loadings and boundary conditions were performed. It was found from the results of the analysis that the proposed protection-pipes are able to meet the requirements of TPC set for the electricity power cable laid under seawater.

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Analysis on a Cast-Iron Pipe Applied to Protection of Underwater Cable

Dynamic Analysis For The Large Offshore Composite Pipelines Subjected To Waves

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.

Y. Friedmann

Papers

Sea-bottom forces crucial in pipeline crossings design