Hybrid Drilling & Production Concepts for the East Coast - - PowerPoint PPT Presentation
Hybrid Drilling & Production Concepts for the East Coast Offshore Prepared for: Calgary SNAME Branch By: John Fitzpatrick CJK Engineering Ltd. May 2008 Overview CJK ENGINEERING East Coast Production Systems Lessons from the Beaufort
Ice Loads Steel Research Program
Steel GBS for water depths around 140m plus Semi-Rigid Floating Concept
1.0 m 1.0 m
5000 mm
25 mm Pl.
Bottom Shell 25 mm Pl. For drainage
3 6 9 12 15 18 21 24 27 Minimum ultimate structural resistance
Load imparted by contact areas with Cu=2000 psf (uniform)
Average contact stress Clay data point
Plastic failure line, sandy soils (from experience at three sites)
0.5 1.0 1.5 2.0 30 Applied Stress (MPa) Square Root of Loaded Area (m)
25 mm shell Pl. 450 mm x 25 mm 300 mm x 25 mm } Stiffeners at 1000 mm centers, spanning 5000 mm 5000 mm x 1000 mm x 25 mm Typical Panel 1000 mm Typical
Poor post-yield behavior
Thicker Deeper Smaller
Less weight; easier to build; cheaper
Normal Loading Normal Loading Factor of about 20 compared to wL²/12 Factor of about 4 compared to Fy/√3
DESIGN WAVE h = 30 M, WL = 350 m Base Shear 100,000 tonnes Base Moment 5 MM tonne·m DESIGN ICE Iceberg Base Shear 90,000 tonnes Base Moment 6.3 MM tonne·m SOILS - FOUNDATION Friction Angle = 30° or Cu = 125 kPa beneath sand surface. Minimum Effective Contact Force on Bottom = 350,000 tonnes. QUANTITIES 85,000 tonnes EH 36 OLAC steel or equivalent. 130,000 m2 solid ballast with density of 3 tonnes/m3
11
Average cost ~ $400 MM (one-third a
Sand ϕ = 30º; or Clay min. Cu ~ 95 kPa
35 m Concrete Ballast Internal Water Ballast Level
Design Wave 27 m Base Shear 100,000 tonnes
1.5
Height to Top Deck 175 m Base (octagonal) 140 x 140 m Base Area 16,000 m2
Steel Grade EH36 OLAC 130,000 tonnes Concrete Ballast 250,000 m3 Design Ice 15,000 tonnes Up to 30 m deep ridges, 4 m thick consolidated layer
Internal Water Ballast Level
Design Wave 27 m Base Shear 150,000 tonnes
1.5
Design Ice 20,000 tonnes Up to 30 m deep ridges, 4 m thick consolidated layer
Sand ϕ = 30º; or Clay min. Cu ~ 140 kPa 95 m
50 50 100 100 135 135
meters meters 20 20
meters meters
50 100 meters
FS = 1.3 with 1 m deflection at 15,000 T horizontal load FS = 1.0 with 5 m deflection at 20,000 T horizontal load
30,000 T buoyancy 27 m wave 20 m Free Board 25 m Draft Water depth range 80 to 400 m
Up to 30 m deep ridges, 3 m thick consolidated layer
Sand φ = 33º; or Clay min. Cu = 80 kPa 40,000 T Scrap Iron Ballast inside 55,000 T before Cable tensioning 45,000 T after tensioning 32,000 T during load
ELEVATION IN 250 M WATER
3 Steel Base Anchors Plan area 2500
m2
Steel Structure 15,000 T Iron Ballast 40,000 T Empty & neutral buoyancy during relocation 3 Sets of Cables 45º angle to vertical 120º in plan; Each set: 48 x 90 mm, 890 T Cables Platform: Hull Steel Weight 30,000 T Payload in Transit 15,000 T Top Deck 8000 m2 Top Deck Diameter 100 m Cable Handling Deck Diameter 70 m Moon Pool Diameter 15 m Water ballasted during anchoring
50 100 meters
TOP VIEW ON OCEAN FLOOR IN 250 M OF WATER
Ice Load Equals 50% Buoyancy, Note Lack of Rotation
Ice force 15,000 Tonnes, Buoyancy 30,000 Tonnes
30,000 28,284 7,071 7,071 60 30,000 28,069 9,305 5,052 50 30,000 27,431 11,686 3,309 40 30,000 26,390 14,142 1,895 30 30,000 24,976 16,598 853 20 30,000 23,233 18,979 215 10 30,000 21,213 21,213
(just about to go slack)
Points to 240 degrees Points to 240 degrees Points to 120 degrees Points to the north, for ease of reference ‘0’ degrees means ice comes from the south Excess Buoyancy force on structure or downwards vertical component of all three cable groups CG3 tensile force in tonnes CG2 tensile force in tonnes CG1 tensile force in tonnes. Angle of Attack of 15,000 tonne ice force in degrees.
13m /8m 60,000 48,990 30,000 tonnes 10m/6m 50,000 40,825 25,000 tonnes 5m/3m 40,000 32,998 20,000 tonnes 1m/0m 30,000 28,284 15,000 tonnes Approximate amount structure would move sideways and downwards Excess buoyancy requirement Maximum Cable Group force in tonnes Ice load/ effect
Main Deck Moon Pool Lower Deck Winch Deck Cable Slots Inner Bottom Bottom Anchor Top Iron Ballast Anchor Btm. Skirt Tip
½ INBOARD PROFILE
3 x 16 Reel Sets Serving One Anchor
15 MW Gas Turbine & Air Compressor
Moon Pool 15 m Dia.
WINCH DECK PLAN 70 m DIA.
Cable Slot Underneath
PLAN VIEW
EACH REEL: 3.30 M DIA x 1.75 M LONG
Reel Winch Deck
Motor
Cable Grip -Closed Slot
MOORING SYSTEM SCHEMATIC WHILE ANCHORED (N.T.S.)
Inner Bottom Bottom Hawser
Cable toward Anchor
30,000 Tonne Stiff or Non Compliant System Under 27m Wave
700 Grand Total 70 Item Contingency 30 Item Hull and anchor assembly and tow to first site. 30 Item Engineering and approvals 5 Item Ballasting system for upper hull 30 $200,000 144 Spools, Supports and winch motors 40 2 Gas Turbine Compressor 100 $1100/m 90,000m Cables 60 $250/t 240,000 t Steel Ballast (scrap) 65 $3000/t 22,000 t Anchor 3 65 $3000/t 22,000 t Anchor 2 65 $3000/ t 22,000 t Anchor 1 140 $3500/t 40,000 t Upper Hull
Cost 2006 dollars (MM USD)
Unit Cost Quantity Item