Showing papers on "Submarine pipeline published in 1969"

Geological Significance of North Sea Sand Transport Rates

Abstract: THE history of many marine sandstones is difficult to determine because the origins of Quaternary sands of offshore shallow seas, to which they may be equivalent, are not yet known. To lessen this gap in our knowledge, a quantitative observational and theoretical study is being made of sand transport and deposition in the southern bight of the North Sea near Holland, for which a qualitative interpretation is already available1. There is probably as much information about currents, sediment grade and sorting, and wave heights and spectra, for this area as for any other sea in the world. In general terms, the southern part has near-surface tidal currents which reach peak speeds of about two knots and the floor of medium sand grade is wrought into large sand waves approximately transverse to the flow. In the northern part, the tidal currents are weaker, and the floor of very well sorted fine sand is flat or probably ripple marked. In between, there is a narrow zone of small sand waves with crest separation of about 10 m (Fig. 1). The inferred net travel of sand is from south to north, with erosion at the southern end and deposition all along the northern reaches of this transport path. The depth of water is only about 80–120 feet; both tidal currents, and wind-produced currents and waves, can be important.

Submarine pipeline laying

Abstract: A method and apparatus are described for laying pipelines or the like on the bottom where the degree of bending in the line at all points between a lay barge and the bottom are controlled. The line is paid out of the barge in a horizontal direction with positive buoyancy at the surface. Means are provided for gradually decreasing the positive buoyancy of the pipeline as a function of distance aft of the barge until the line is neutrally buoyant and then gradually increasing negative buoyancy of the line as a function of distance until the line is near the bottom. A plurality of buoyancy controlling elements within the pipeline and attached to the barge by means of a cable is employed for gradually changing buoyancy.

Method for laying submarine pipelines

Abstract: A method of laying pipes to form an underwater pipeline where pipes are floated to the point of immersion. A mud is injected into a floating pipe to sink the pipe to a predetermined level for connection with a submerged pipe. The pipe sections are connected by conventional means, and the procedure is repeated until the pipeline is finished. Traction arms and stoppers can be added to the pipe prior to immersion to assist in the laying of the pipeline.

Method of burying sub-sea pipelines, cables and the like

Abstract: 1286521 Excavating earth NEDERLANDSE MAATSCHAPPIJ VOOR WERKEN BUITENGAATS (NEDERLANDS OFFSHORE CO) NV 10 April 1970 [10 April 1969 21 July 1969] 18538/69 and 36650/69 Heading E1F [Also in Divisions F2 and H2] A method of burying pipelines, etc. in the bottom of the sea includes laying a pipeline on the bottom of the sea and lowering a plurality of trenching devices one behind the other along the pipeline, the devices being designed to loosen the seabed beneath the pipeline and to convey the loosened material from beneath the pipeline, and advancing the devices in one direction only along the pipeline, successive ones of the trenching devices increasing the depth of the trench beneath the pipeline and being so spaced apart 'that the pipeline over which the devices have passed reaches a predetermined depth in the trench. The devices may be coupled together to form a train and may be advanced along the pipeline either by means attached to the leading device or by respective motive units associated with each device and controlled to give synchronised movement to the devices. Such motive units may consist of pairs of clamping means 43, 44 connected by cylinder 48 and piston 45 means and arranged to be alternatively clamped to and moved along the pipeline so as to advance the device there-along. The devices are preferably fitted with rotary cutters 37 and/or water jet causing devices 85 for loosening the material beneath the pipe. Such cutters are preferably moveable from a position in which they astride the pipe so as to be capable of being lowered over the pipe to a position under the pipe. Each device is also preferably provided with suction means 33 for conveying away the loosened material and conveying it to the rear of the trailing device and depositing it therebehind so as to in-fill the trench after the pipeline has been deposited therein. The devices may also incorporate levelling and buoyancy adjusting means and may be controlled from a pipe-laying vessel, their speed of operation being automatically controlled with changing soil conditions.

Late Quaternary geology of a potential wind-farm area in the Kattegat, southern Scandinavia

Abstract: Following the proposal of the offshore Anholt wind-farm project with an energy capacity of 400 megawatt in the Kattegat, southern Scandinavia, an evaluation of the geotechnical properties of the subsurface of the area is required. As a first step to map the seabed geology the Geological Survey of Denmark and Greenland (GEUS) conducted a geophysical survey (Leth et al. 2009) which, together with cone penetration tests and data from boreholes, lead to a greater understanding of the geological architecture and development of the 144 km 2 survey area (Figs 1, 2). Methods We used a multibeam echo-sounder for detailed mapping of the bathymetry, and shallow seismic equipment and coring to map the shallow seabed geology including the distribution and thickness of the main geological units. A combination of two seismic devices (chirp and sparker systems) was chosen to ensure good penetration and high resolution. The sparker system provides data from the sea floor down to about 45 m into the seabed with a vertical seismic resolution in the order of 50 cm, while the chirp system provides high-resolution seismic data from the upper 5–10 m of the seabed with a vertical seismic resolution at decimetre scale. A side-scan sonar was used for mapping of surface sediments. At seven sites, boreholes were made to a depth of 40 m and selected intervals sampled. Cone penetration tests were carried out at the same sites (Fig. 2) and surface sediment samples collected for biological studies.

The Submarine Pipeline And Single Buoy Mooring

Abstract: A survey covers the components of the single buoy mooring system, its purpose, and its operation; design of the submarine pipeline, the bottom manifold, the underbuoy hose, the buoy, and the floating hose strings; operations of mooring tankers, connecting hoses, loading and offloading, disconnecting the floating hoses, and leaving the mooring; and especially those areas critical to pollution prevention.

69-kV High-Pressure Oil-Filled Pipe-Type Submarine Lines to Offshore Drilling Islands

Abstract: A dual 69-kV high-pressure oil-filled pipe-type cable system was recently installed by the Southern California Edison Company, Los Angeles, Calif., to serve four offshore oil drilling islands in Long Beach Harbor. Each line is capable of carrying the entire load with parallel line out of service. A submarine pipeline was severed and repaired. Cable pulls, believed to be the longest on record, are discussed. Cable tests indicate higher permissible pulling tensions.