Statpipe landfall approach solves rocky shore problems

Journal Article · Mon May 12 00:00:00 EDT 1986 · Oil Gas J.; (United States)

OSTI ID:5515846

Lund, S; Gjertveit,

The irregular seabed conditions encountered during the Statpipe project included rocky subsea shore areas at the pipeline's landfall. Part 1 focused on subsea irregularities along the Norwegian Trench. Traditional pipeline landfall is on a sandy beach, into which a trench is excavated for subsequent pull-in of the pipe from the lay-barge. Excavation of a trench, although not in sand but in solid rock, was also considered for the Statpipe landfall at Kalsto. The seabed is mostly rocky for about 900 m from the coastline along the selected landfall route, with large local variations in water depths. Further out, to about 1,200 m, is a steep slope down to soft sediments at about 100-m water depth. The area is directly exposed to wind and waves from the North Sea, which significantly affects design and installation criteria. The topography as well as the exposure to the environment made this shore approach a challenge. A trench through the rocky shore approach zone would require more than 40,000 cu m of rock to be blasted and removed. This trench would at some spots be more than 12 m deep. Blasting would have to be performed to a water depth of 40-50 m. After pipeline installation, the trench would have to be completely backfilled in order to stabilize and protect the pipeline. This backfill would again require a thick protective layer of large stones in the wave-breaking zone. The trench excavation was found to be entirely feasible with some modification to existing equipment. The schedule was uncertain, however, because of the exposure of the landfall area to winds and waves.

• Research Organization: Den norske stats, oljeselskap A.S. (Statoil), Stavanger
• OSTI ID: 5515846
• Journal Information: Oil Gas J.; (United States), Vol. 84:19
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
NATURAL GAS
TRANSPORT
PETROLEUM
PIPELINES
INSTALLATION
POSITIONING
BACKFILLING
BARGES
DEPTH 1-3 KM
DIRECTIONAL DRILLING
EXCAVATION
EXPLOSIVE FRACTURING
HOISTING
MARINE RISERS
NORTH SEA
OFFSHORE OPERATIONS
ROCKS
ROUTING
SEA BED
SEDIMENTS
SHORES
TOPOGRAPHY
WAVE FORCES
WIND LOADS
ATLANTIC OCEAN
COMMINUTION
DEPTH
DIMENSIONS
DRILLING
DYNAMIC LOADS
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FRACTURING
FUEL GAS
FUELS
GAS FUELS
GASES
MATERIALS HANDLING
PIPES
SEAS
SURFACE WATERS
022000* - Petroleum- Transport
Handling
& Storage
032000 - Natural Gas- Transport
Handling
& Storage