Showing papers on "Submarine pipeline published in 1997"

Protection of pipeline joint connections

Abstract: A method and apparatus for protecting exposed pipeline joints on weight coated pipelines used in offshore applications. The method allows quick installation on a lay barge where pipeline sections are being welded together for offshore installation. The method does not require a long cure time before handling. The method protects the corrosion coating (24) on pipeline joint sections (18, 18A) not covered with a weight coat by forming a pliable sheet of polyethylene into a cylindrical cover material sleeve over the exposed pipeline joint connection. Polyurethane chemicals are reacted to form a high density foam (52) which fills an annular space between the pipe and the cover material sleeve (40). The cover material sleeve and the foam form a composite system to protect the joint connection whereby the foam provides continuous compressive reinforcement and impact resistance and the sleeve provides puncture resistance and protection from water jetting/post trenching operations plus abrasion resistance.

Interactive 3D tools for pipeline route planning

Abstract: With their ability to efficiently provide high-resolution bathymetry with complete coverage over wide swaths of the seafloor, multibeam sonars are increasingly becoming a standard tool for the planning of marine engineering projects such as pipelines and communication cables. In addition to high-resolution bathymetry, most modem multibeam sonar systems also provide sonar backscatter data, an indicator of surficial texture or material type. These data sets are combined with high-resolution seismic, standard sidescan and ground truth (coring or geotechnical) data to allow the marine engineer to make optimal judgments about the route of a submarine pipeline or cable. Huge volumes of data are generated by the different survey systems, often running into hundreds of megabytes. Typically this data is only available to the engineer in the form of a paper atlas with each type of data presented separately. We present a suite of software tools (the Fledermaus Toolkit) designed to present data in a three dimensional visual format, allow its interactive exploration, and to quantitatively interrogate the data within the 3-D space for geographic information and other attributes (depth, gradients, etc.). Cable and pipeline routes are planned interactively by simply drawing the route on the seabed and adjusting the route as needed. Two-dimensional and three-dimensional views of the route are simultaneously available when necessary.

The Morphogenesis of Submarine Springs in the Bay of Kaštela, Croatia

Abstract: Offshore, in the Bay of Kastela, karst groundwater, which initially flowed under a hanging karst barrier, flows out from two submarine springs. The water flows from fissures enlarged by corrosion and erosion at sites that were previously coastal karst springs. They were submerged due to sea level rise at least 7,000 years ago and, since that time, they function as submarine springs, at about 32-35 m below sea level.

Characteristics of Submarine Topography off Northern Taiwan

Abstract: Based on bathymetric data collected in recent years, the topographic features and their structural implications on the northern offshore area of Taiwan are described. The Chilung Shelf is representative of the submarine physiographic units in this region. It occupies the shallow water area eastward to the City of Chilung between the Chilung Valley and the Mien-Hua Canyon. To its north and west, the East China Sea Shelf reveals a gentle ocean bottom such that water depths on its edge (the shelf break) are found to be at least 150 meters shallower than those on the Chilung Shelf. Taiwan is a product of orogeny which resulted in compressive imprints throughout the island. On the Chilung Shelf, a series of topographical lineaments extending from onland Taiwan and oriented in the SW-NE direction are present; however, seismic profiles indicate that these lineaments are a factor of normal faulting mechanics. It is suggested that the offshore area of northern Taiwan has been under a different tectonic stress from that represented on the island. (

Heated offshore pipeline and method of manufacturing

Abstract: A submerged marine pipeline (201) is electrically insulated from sea water and is heated by alternating current that flows through the pipeline, where the AC power supply (212) is grounded to ambient sea water (206) The insulating material is cast between an assembled length of a pipeline or bundle of pipelines and molds that are continuous, or directly to one another along and around the assembled length, before it has been placed at its final destination

Comparison of Fine-Grained, Mud-Rich and Coarse-Grained, Sand-Rich Submarine Fans for Exploration-Development Purposes

Abstract: Downdip sand/shale ratios, internal architecture, sand body geometries and connectivities are major aspects that differ between fine-grained, mud-rich and coarse-grained, sand-rich submarine fans. Such differences have a direct impact on exploration and development strategies. Fine-grained, mud-rich systems are typical for the Gulf of Mexico, offshore Nigeria, and other "passive" margins. Fine-grained fans often start with a major delta and a wide shelf. Relative sea-level lowerings cause basinward transport to the shelfbreak area, rapid deposition with high pore pressures and failure. Slumping will carve a major conduit across the slope. Deposition will start at the base-of-slope with a channel complex, followed by channel-levee-overbank systems and ending with sheet sands. These fans prograde rapidly and then tend to switch laterally. The channel complex and the sheet sands have a high sand/shale ratio, the leveed channel area a low one, except for the channel fill. Coarse-grained, sand-rich submarine fans commonly are formed off mountainous coasts where a high sand/shale sediment input is typical. The narrow shelf is less influenced by sea-level fluctuations to pass sediment across. Gradual progradation of a fan across the basin floor is typical. The interchannel area is sand-rich and a general basinward decrease in sand/shale ratio is common. Although no model should be applied blindly for any field, it is advisable to start with the most applicable one, and to insert changes with the increase of data obtained during the different phases of field development. The two end members (fine-grained and coarse-grained) will provide a start for any selection.

Signatures of Wave and Current Forcing on the Seabed about a Large Coastal Headland

Abstract: We question whether large headlands act as total barriers to sand transport, thereby closing littoral cells, or whether waves and currents combine to carry sediment from cell to cell. At Cape Rodney, a blunt-nosed feature protruding 4 km offshore into 50 m water depth, sediments and bedforms were mapped using SCUBA, seabed sampling, and side-scan sonar. Wave and current spatial variation was determined using vector-averaging and acoustic doppler current meters to establish numerical hydrodynamic and wave models. Two large counter-rotating phase eddies were identified, one on either side of the headland. The eddies create pronounced current asymmetry in a band (some 4 km longshore by 4 km cross-shore) against the headland shoreline. The signature of the eddies was strongly evident in the seabed sedimentary characteristics and in the patterns of winnowing and deposition. The signature of the waves was coarse-sediment megaripples aligned with the directions of waves. Phase eddies drive sediment towards the headland thereby enhancing the potential for sediment bypassing. Sediment may also be lost or recirculated via the shoreface into deeper waters offshore.

Near Shore Wave Processes

Abstract: : Long-term goals are to predict the wave-induced three-dimensional velocity field and induced sediment transport over arbitrary bathymetry in the near shore given the offshore wave conditions.

Repetitive surveys to assess sand ridge movement offshore Sable Island

Abstract: A considerable amount of seabed information has been collected over the years on the Scotian Shelf near Sable Island. The seabed around Sable Island is composed predominantly of sands and its morphology is characterized by numerous large sand ridge features and smaller megaripple fields. It has been speculated that the larger sand ridge bedforms are storm generated and are possibly moving, at least on an intermittent basis. The objective of this paper is to present comparative measurements to shed light on how much the seabed has changed over a time period of engineering significance. The fact that the top surface sands are actively mobile from storm to storm is not disputed nor is it the subject of this paper. The focus of this paper is to evaluate the change of the underlying bedforms based on repetitive surveys. In the past it was difficult to evaluate bedform migration due to navigation uncertainty and the large line spacing (and resulting low data density) of bathymetric measurements. With the availability of differential global positioning systems (DGPS) and swath bathymetry in recent years, a more accurate evaluation of sand ridge movement can now be made. Coincident swath surveys from 1995 and 1996 are compared to each other, and to various data sets from the 1980s to evaluate sand ridge movements over a maximum of 16 years. The amount of potential sand ridge movement is important to pipeline design. If the sand ridges are moving then buried pipelines may become exposed over time creating free-spans and possible pipe overstress conditions. Thus it is important to understand the magnitude of seabed migration over the design life of the pipeline.

Cathodic protection retrofit of an offshore pipeline

Abstract: Cathodic protection (CP) anodes and corrosion coating on two offshore pipelines were damaged during deep water installation. In-situ methods for deep-water inspection and repair of the pipelines` CP and coating systems were developed and used. High-pressure natural gas Pipeline. A design was 5.6 miles of 8.625 in. OD by 0.406 in. W.T. API SL, Grade X-42, seamless line pipe. Pipeline B design was 0.3 miles of similar specification pipe. Both pipelines were mill-coated with 14 mil of fusion-bonded epoxy (FBE) corrosion coating. Girth welds were field-coated with FBE.

Regeneration of a Marine Ecosystem after Pipeline Decommissioning

Abstract: Waste acid-based pickling liquor (5 g/L HC1, Fe 120 g/L) from the galvanising process of BHP at Port Kembla, N.S.W, Australia, was discharged to the South Pacific Ocean via a submarine pipeline from 1955 until its de-commissioning in 1991. Twelve ecological surveys of the marine benthos of the receiving waters between 1973 and 1995 found increases in infaunal populations with improvement to discharge practice. Within four years of de-commissioning the marine benthos had returned to normal for ocean waters.

Natural gas in new zealand

Abstract: ALTHOUGH THE FIRST (small) commercial hydrocarbon discovery in New Zealand was made in 1866, it was not until 1959 that modern exploration resulted in the onshore discovery of the gas-condensate Kapuni field in the Taranaki Basin, followed in 1969 by the discovery of the giant offshore Maui gas-condensate field. The last two decades have seen the development of these two fields, augmented by several smaller gas- and oilfields. An extensive gas pipeline system has been put into place in the North Island. The South Island gas needs are served by tankers and bottles.

Tomographic Imaging of the Shear-wave Velocity Structure of the Shallow Seabed of the New Jersey Continental Shelf and On-bottom Seismographs for Shallow Seismic Imaging of the Continental Shelf Seabed

Abstract: : Long Range Scientific Objectives. The long range goals of this project are to map the three-dimensional, shear- and compressional-wave velocity structure of the upper 50-100 m of the seabed, to correlate these measurements with geological structure, and to use the spatial variability in velocity structure to understand the depositional and erosional processes responsible for the measured structure. Scientific Objective. The immediate scientific objective of this program is to carry out a three-dimensional shear-wave tomography experiment on the continental shelf offshore New Jersey in an area that has been extensively surveyed with high-resolution, seismic reflection imaging techniques. The motivation for the proposed work is our belief that, in many geological settings, the internal structure and geometry of sedimentary facies are sufficiently complex that they can be determined only by carrying out a three-dimensional experiment. This experiment will take place in the summer of 1998.