Scour in the North Sea
Scour or seabed erosion around drilling and production platform legs and pipelines in the North Sea can be a major environmental problem because of the combination of shallow water depths, fast tidal currents, and mobile sand waves and banks. Considerable progress has been made in recent years toward understanding the mechanism of seabed scour around offshore platforms, but the North Sea's complex environmental conditions are difficult to reproduce in laboratory test tanks. Two types of scour appear to occur simultaneously around North Sea offshore structures located on an unconsolidated seabed. The first is a local scour resulting from the interaction between individual piling and the current, the second a general scour resulting from the effect of the total structure on the current. Successful antiscour methods prevent further erosion, fill in the scour hole, and restore the seabed to its original level. ASD (antiscour device) nets have enjoyed only spotty success; if properly designed and securely anchored to the seabed and structure, individual nets could provide an effective and economic form of scour protection. The ability of the SDD (sedimentary deposition device) carpet system to prevent scour and replace lost seabed material at low installation and maintenance costs favors its continued use around southern North Sea structures. The high cost of transportation and installation makes large-scale protection methods such as gravel dumps extremely expensive in this area. Protection schemes such as cement aprons and sandbags are usually uneconomic because of secondary scour; the protection can be quickly undermined, making replacement necessary. The scouring action of the current begins as soon as the structure is installed, and much of the scour hole is formed within the 1st 2 weeks. Thus, if proven scour protection methods are implemented immediately after a structure is installed, the scour effect can be eliminated.
- OSTI ID:
- 7015333
- Journal Information:
- J. Pet. Technol.; (United States), Vol. 26
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
NORTH SEA
SEA BED
OFFSHORE PLATFORMS
STABILITY
EROSION
NATURAL GAS FIELDS
OIL FIELDS
ATLANTIC OCEAN
GEOLOGIC DEPOSITS
NATURAL GAS DEPOSITS
PETROLEUM DEPOSITS
RESOURCES
SEAS
SURFACE WATERS
020300* - Petroleum- Drilling & Production
030300 - Natural Gas- Drilling
Production
& Processing