Goodwyn a Steel Jacket Offshore Platform
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Goodwyn "A" Steel Jacket Offshore Platform, Australia Year of Completion: 1993 Design Fee: $65,000 Client: Woodside Offshore Petroleum Pty. Ltd. Services Performed: • Large-Diameter Piles • Non-linear Soil-Pile Interaction • Concrete Mix Design Pre-cast concrete segmental inserts. Ben C. Gerwick, Inc. 06-094e-02a The Goodwyn “A” steeljacket offshore platform is piled to the seafloor in 130 m deep water on the North West Shelf of Australia. BCG, Inc. was retained to evaluate pile installation procedures. In 1993, Woodside Offshore Petroleum Pty. Ltd. completed construction of the Goodwyn “A” steel jacket offshore plat- form which will be piled to the seafloor in 130 m deep water on the Northwest Shelf of Australia. Due to the difficult soil conditions at the Goodwyn “A” site, considerable attention has been paid to the foundations. It was decided to use 2.65 m O.D. driven primary piles to a depth of 116 m below the mudline, and then to install two m O.D. drilled and grouted insert piles to a depth of 181 m below mudline. The marine contractor for this work, Heerema McDermott Aust. Pty. Ltd. elected not to use “float shoes” on the ends of the insert piles which would have kept grout out of the insert piles. However, due to this lack of float shoes concern was raised both re- garding: (a) The influence of the proposed grout placement procedures on the quality of the grout (b) The thermal consequences from heat of hydration of grout in the interior of the piles Ben C. Gerwick, Inc. was retained to assist Woodside to evaluate the con- sequences of the marine contractor’s proposal to allow the grout to flow up the interior of the insert pile and then out through staggered port holes drilled in the sides of the insert piles, thus filling the annular space between the insert pile and the primary pile and the calcarenite soils. In order to help evaluate the proposed grouting proce- dures, Heerema McDermott conducted large scale physical grout flow tests, and physical heat of hydration tests, as well as finite element analysis. After review of the findings of these, and other studies, it was concluded that: (a) A practical grout mix, incorporating both Portland cement and granu- lated blast furnace slag could be developed that could flow through reasonably spaced and sized side ports in the insert piles without undue reduction in grout bond quality due to such factors as having the grout mix with sea water in the annular space. (b) Thermal stresses resulting from the heat of hydration of the grout on the interior of the insert piles would be unacceptable, even when using low heat of hydration grouts. Consequently, a system for replac- ing much of the grout in the interior of the piles was developed, using precast concrete segmental inserts. These were lowered into the interior of the insert piles after they had been installed. This system proved adequate to limit the heat of hydration and the consequent thermal stresses. Elevation of the Goodwyn “A” offshore platform.
Transcript of Goodwyn a Steel Jacket Offshore Platform
Goodwyn "A"Steel Jacket Offshore Platform, Australia
Year of Completion: 1993
Design Fee: $65,000
Client: Woodside Offshore
Petroleum Pty. Ltd.
Services Performed:
• Large-Diameter Piles
• Non-linear Soil-Pile Interaction
• Concrete Mix Design
Pre-cast concrete segmental inserts.
Ben
C. G
erw
ick,
Inc.
06
-094
e-02
a
The Goodwyn “A” steeljacket offshore platform is piled to the seafloor in 130 m deep water on the North West Shelf of Australia. BCG, Inc. was retained to evaluate pile installation procedures.
In 1993, Woodside Offshore Petroleum Pty. Ltd. completed construction of the Goodwyn “A” steel jacket offshore plat-form which will be piled to the seafloor in 130 m deep water on the Northwest Shelf of Australia. Due to the difficult soil conditions at the Goodwyn “A” site, considerable attention has been paid to the foundations. It was decided to use 2.65 m O.D. driven primary piles to a depth of 116 m below the mudline, and then to install two m O.D. drilled and grouted insert piles to a
depth of 181 m below mudline. The marine contractor for this work, Heerema McDermott Aust. Pty. Ltd. elected not to use “float shoes” on the ends of the insert piles which would have kept grout out of the insert piles. However, due to this lack of float shoes concern was raised both re-garding:
(a) The influence of the proposed groutplacement procedures on thequality of the grout
(b) The thermal consequences fromheat of hydration of grout in theinterior of the piles
Ben C. Gerwick, Inc. was retained to assist Woodside to evaluate the con-sequences of the marine contractor’s proposal to allow the grout to flow up the interior of the insert pile and then out through staggered port holes drilled in the sides of the insert piles, thus filling the annular space between the insert pile and the primary pile and the calcarenite soils. In order to help evaluate the proposed grouting proce-dures, Heerema McDermott conducted large scale physical grout flow tests, and physical heat of hydration tests, as well as finite element analysis.
After review of the findings of these, and other studies, it was concluded that:
(a) A practical grout mix, incorporating
both Portland cement and granu-lated blast furnace slag could bedeveloped that could flow throughreasonably spaced and sized sideports in the insert piles withoutundue reduction in grout bondquality due to such factors ashaving the grout mix with sea water
in the annular space.(b) Thermal stresses resulting from the
heat of hydration of the grout onthe interior of the insert piles wouldbe unacceptable, even when usinglow heat of hydration grouts.Consequently, a system for replac-ing much of the grout in the interiorof the piles was developed, usingprecast concrete segmental inserts.These were lowered into theinterior of the insert piles after theyhad been installed. This systemproved adequate to limit the heat ofhydration and the consequentthermal stresses.
Elevation of the Goodwyn “A” offshore platform.
