1November 2006

Review of Deepwater Floating Structuresand Dry Tree Semi

Developments

2Deepwater Structures

Spar

Industry Accepted Because: Proven - Many years of

Operating history Functional - Used for a large

variety of functions, wet or dry tree

Scaleable Wide range of topsides payloads

Adaptable Applications worldwide

Tension Leg Platform (ETLP)

Semi-submersible (Semi)

3Optimum Application Ranges

0

10,000

20,000

30,000

40,000

50,000

0 2,000 4,000 6,000 8,000 10,000Water Depth (ft)

F

a

c

i

l

i

t

y

P

a

y

l

o

a

d

(

s

t

)

SparsSemisTLP

Spar

SemiTLP

4Deep Draft Semi Dry Tree Semi

DeepDraftDeepDraftTMTM SemiSemi

ESemi-II

5TLP Design

Low heave and pitch natural periods (less than 4 seconds)

Minimum tether tensions

Minimum bending loads on TLP deck structure to reduce steel

Offset and set-down motions that can be tolerated by the riser system

Stability during installation and quayside HUC

6Extended TLP (ETLP) Construction

7ETLP Transit

8Quayside Topsides Installation

9Structural Weight Efficiency Ratio

Structural Weight Efficiency =

Total Topsides Payload

Total Hull Plus Deck Weight

Total Topsides Payload =

Weight of all deck equipment and facilities including quarters, drilling systems, etc. Also includes TTR loads, SCR loads and secondary deck steel. Topsides equipment or facilities carried in the hull, and hull ballast earmarked for future expansion are also included.

Total Hull Plus Deck Weight =

Structural steel weight of hull, hull marine systems, hull appurtenances and outfitting, and trim ballast. Also includes deck primary structural steel weight.

Structural Weight Efficiency =

Total Topsides Payload

Total Hull Plus Deck WeightStructural Weight

Efficiency =Total Topsides Payload

Total Hull Plus Deck Weight

Total Topsides Payload =

Weight of all deck equipment and facilities including quarters, drilling systems, etc. Also includes TTR loads, SCR loads and secondary deck steel. Topsides equipment or facilities carried in the hull, and hull ballast earmarked for future expansion are also included.

Total Hull Plus Deck Weight =

Structural steel weight of hull, hull marine systems, hull appurtenances and outfitting, and trim ballast. Also includes deck primary structural steel weight.

Total Topsides Payload =

Weight of all deck equipment and facilities including quarters, drilling systems, etc. Also includes TTR loads, SCR loads and secondary deck steel. Topsides equipment or facilities carried in the hull, and hull ballast earmarked for future expansion are also included.

Total Hull Plus Deck Weight =

Structural steel weight of hull, hull marine systems, hull appurtenances and outfitting, and trim ballast. Also includes deck primary structural steel weight.

10

Efficiency Ratio Ranges for TLP Designs

Structural Weight

Efficiency

Structural Weight

Efficiency==

Total Topsides PyldTotal Topsides PyldTotal Hull + Deck WtTotal Hull + Deck Wt

Hull Form / LocationDesign Maturity

Ratio Range

TLPs in GoM As-Built 0.6 0.8

ETLPs in GoM As-Built 1.1 1.2

ETLPs in SE Asia Conceptual 1.4 1.5

ETLPs in W Africa As-Built 1.3 1.4

11

Spar Design

High heave and pitch natural periods (greater than 25 seconds without risers)

Maximum offset of 7-9% water depth in damaged conditions

Maximum heel angle less than 10 in intact and damaged condition.

Wet tow draft shallow enough to offload hull if transport vessel is used

Structural strength for up-righting during installation.

12

Spar Construction

13

Spar Construction

14

Spar Transportation

15

Spar Installation

16

Spar Topsides Installation

17

Relative Deck Areas

Spar

Semisubmersible&

TLP

18

Wellbay Layout - TTRs

19

Riser Tensioner

20

Design Basis Comparison of Hull Forms

GoM Environment 60 MBOPD & 200 MMCFD 20-person accommodation Work-over rig Hydro-pneumatic tensioners on TTRs

21

Metocean Conditions for Comparison

100-Y ear H u rric an e C o n d itio n sW ATE R D E P TH (ft) 4 ,700

W AV E SS ig n if ican t W ave H e ig h t (f t) 40 .4P eak P e riod (sec) 14 .2M axim um W ave H e ig h t (ft) 70 .2

W IN D S - R eferen ced to 10m ab o ve M S L1 -H ou r S usta ined W ind S peed (ft/sec) 128

C U R R E N T S P E E D (ft/s )S urface 3 .6197 ft 3 .6328 ft 0 .65490 ft 0 .65656 ft 0 .65980 ft 0 .651640 ft 0 .65N ea r-B o ttom 0 .65

22

Hull Forms and Dimensions

23

Comparison of Weights and Payloads

0

5,000

10,000

15,000

20,000

25,000

Tops

ides

Lights

hip

Moori

ngs

SCR

TTRs

Balla

st

W

e

i

g

h

t

(

s

t

o

n

s

)

ESEMISparETLP

24

Tensioner Characteristics

Offset - Tension Curves

0

300

600

900

1200

1500

1800

2100

-16.0 -12.0 -8.0 -4.0 0.0 4.0 8.0 12.0 16.0

Stroke (ft)

T

e

n

s

i

o

n

(

k

i

p

s

)

TLP ESEMI Spar B-Can

25

Well Patterns

26

Surge Comparison

Surge RAO Comparison

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0.0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0

Periods (sec)

S

u

r

g

e

R

A

O

(

f

t

/

f

t

)

ETLP ESEMI Spar

27

Pitch Comparison

Pitch RAO Comparison

0.00

0.05

0.10

0.15

0.20

0.25

0.0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0

Periods (sec)

P

i

c

t

h

R

A

O

(

d

e

g

/

f

t

)

ETLP ESEMI Spar

28

Heave RAO Comparison

0.00

0.10

0.20

0.30

0.40

0.50

0.0 3.0 6.0 9.0 12.0 15.0 18.0 21.0 24.0

Periods (sec)

H

e

a

v

e

R

A

O

(

f

t

/

f

t

)

ETLP ESEMI Spar

Heave Comparison

29

Motion Response 100-Year Hurricane Intact Condition

0.00

4.00

8.00

12.00

16.00

20.00

Offset

(% de

pth)

Heave

Range

(ft)

Heel (

deg)

Yaw (de

g)

Deck

Acc. (ft

/sec2)

R

e

s

p

o

n

s

e

ESEMISparETLP

30

Comparison of Range of Strokes

-18.00

-14.00

-10.00

-6.00

-2.00

2.00

6.00

10.00

14.00

max u

pstrok

e (ft)

max d

nstrok

e (ft)

max u

pstrok

e (ft)

max d

nstrok

e (ft)

max u

pstrok

e (ft)

max d

nstrok

e (ft)

R

e

s

p

o

n

s

e

ESEMISparETLP

100-Yr Intact

100-YrMooring Damage

100-Yr Hull Damage

31

Range of Top Tension Factors (TTF)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

max T

TF

min TT

F

max T

TF

min TT

F

max T

TF

min TT

F

R

e

s

p

o

n

s

e

ESEMISparETLP

100-Yr Intact

100-YrMooring Damage

100-YrHull Damage

32

Selection Considerations for a Deepwater Floater

Spar ETLP Dry Tree Semi

Small in-place motions ; ; ;Large open deck areas : ; ;

Dockside HUC of topsides : ; ;Water depth insensitivity ; : ;

Minimum at-sea commissioning : : ;Redeployment ; : ;