TASK2 SUMMARY • CURRENT FORCE • WAVE-DRIFT LOAD • …

/94

TASK2

MOORING LOAD ESTIMATION UNCERTAINTY

1. SUMMARY

2. MEAN ENVIRONMENT LOADS

• WINDFORCE • CURRENT FORCE • WAVE-DRIFT LOAD

3. VESSEL DYNAMIC OFFSETS

• WAVE-FREQUENCY MOTIONS • LOW-FREQUENCY MOTIONS

4. ESTIMATION OF LF DAMPING FORCES

• VESSEL WAVE-DRIFT DAMPING • VESSEL VISCOUS DAMPING • VESSEL AERODYNAMIC DAMPING • MOORING LINE DAMPING

- MATERIAL - SOIL - COUPLED LF-WF MOTIONS

SUMMARY

1. PURPOSE

• TO QUANTIFY LOAD UNCERT A1NTIES • TO PRODUCE INITIAL ENGINEERING ESTIMATES OF LF

DAMPING

2. RELATIVE ACCURACY OF MEAN LOADS

WIND CURRENT WAVE

SEMI GOOD FAIR FAIR

3. RELATIVE ACCURACY OF MOTIONS

SEMI WFMOTION GOOD ~FMOTIOI-{) POOR

4. LF DAMPING PER GO MEX 10-YEAR STORM (%OF SYSTEM CRITICAL, WD = 1000')

SEMI <SEDCO 700)

VESSEL DRlFfDAMPING VISCOUS AERODYNAMIC

MOORING LINES TOTAL

HEAD

.2 1.7 TO 13

2.7 4.6 TO 9.8 9T021%

BEAM

.2 2.5 TO 22

1.9 4.6 TO 9.8 9T034%

SHIP FAIR FAIR FAIR

SHIP GOOD

~

DRILLSHJP CL=380'2

HEAD

1 .2 TO 2.3

2 4T022

7TO 27%

BEAM

2.9 7T026

3.4 9T024

22 T056%

WIND AND CURRENT LOAD

I. VESSEL TYPES

• SEMISUBMERSIBLES • DRILL SHIPS

2. DATA SOURCE

• MODEL TEST DAT A (BASE CASE) • OPERATIONS MANUALS • LITERATURE

3. MAIN FINDINGS ON SEMISUBMERSIBLES

• REASONABLEAGREEMENTFORWINDCOEFFICIENT • SUBSTANTIAL BODY OF KNOWLEDGE

(DUE TO ST ABILITY CONCERNS) • SIGNIF1CANT VARIATION FOR CURRENT COEFFICIENT

4. MAIN FINDINGS ON DRILL SHIPS

• SCANT INFORMATION • SIGNIF1CANT VARIATION FOR WIND COEFFICIENT • WIDE SPREAD FOR CURRENT COEFFICIENT

SEMI-SUBMERSIBLE - WIND COEFFICIENT - HEAD SEAS VALUES NORMALIZED TO MODEL TEST DATA

3 4 5 6 7 8 9 10 11 12 13 14 15 16

1.6

1.4

J QJ

::Iiii 1.2

>-Ill = 0.....a i.o • QJ

.§ I ~0 6

I

§ 0.8

z I <>

0.6

0.4

l 2

?•I •

• I I I I 'i' I •I

I

-t----··+------1

I

0

Rig#

-- -

--- ---

SEMI-SUBMERSIBLE - WIND COEFFICIENT - QUARTERING SEAS VALUES NORMALIZED TO MODEL TEST DAT A

-· ­ ..l.6

'

1.4 - -

-

0

9

T0

Cl<lJ 0:::i ~

I ­ ---·fil 1.2 ­

> •-§ {j i •·i;; 1.0 .

~ ~ ~ 1 ­

.§ .

Cl l ­

I •§ 0.8 -z

0.6 - ­ -

. . . .0.4 - ' l ' ' ' ' , ;- ' ' ' ' -l I I I I' ' '

.

' ' 1 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16

Rig#

SEMI-SUBMERSIBLE - WIND COEFFICIENT - BEAM SEAS VALUES NORMALIZED· TO MODEL TEST DATA

1.6

1.4

QI::sIii 1.2

> Iii §

·;;; 1.0

61 .§ Cl

I

~ 0.8

0.6

0.4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Rig#

-

-

• ,] l

' '

---·

'

iJ

• l

n I ·_L_9

I t•

I ~ ~

0 I •.

l)

• I)

' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' '

SEMI-SUBMERSIBLE - CURRENT COEFFICIENT - HEAD SEAS VALUES NORMALIZED TO MODEL TEST DATA

1.8

1.6

~ l.4

-~ ~ 1.2 0......

5 .§ 1.0

~ z 0.8

0-6

0.4

-

• I

[l

' (

!) I I)•

• ljl i

~ LI -

•

• ll

1---f----l ' ' ' ' ---+----!I I I I I I

' ' ' ' ' ' '' ' ' 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Rig#

1

SEMI-SUBMERSIBLE - CURRENT COEFFICIENT - QUARTERING SEAS VALVES NORMALIZED TO MODEL TEST DAT A

1.6 -

1.4

(lJ

=-; 1.2 ?-11:1 c:: Q.....5 1.o

.§0

I

§ 0.8

z

(

I I I I I I

I 0

I

I

I •

0

i;i

b i!i

0

•

1

i

I

0

0.6 +­0

I

0.4 ·-·-+----!

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Rig#

SEMI-SUBMERSIBLE - CURRENT COEFFICIENT - BEAM SEAS VALUES NORMALIZED TO MODEL TEST DATA

1.6

1.4

Cl.I::s'iU 1.2

>-~ 0 '!il 1.0

5 .§c;i § 0.8

z

0.6

0.4

(

-

. I

'

! !)

[] 9

ti -w w

() I

•

• •

[

[)

' t t I I I ' t I ' ' I 1---1--­' ' I I I I I . ,­ I '

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Rig#

DRILL SHIP - WIND COEFFICIENT - HEAD SEAS VALUES NORMALIZED TO MODEL TEST DATA

-

QJ

::i 'iU

1.8

1.6

1.4

> 1.2 'iUc: 0

·t;; l

5 .§ ~ 0.8

~ 0.6

0.4

0.2

-

I ]

b

I ' I

• • •

4l 2 3

Drill Ship#

DRILL SHIP - WIND COEFFICIENT - QUARTERING SEAS VALUES NORMALIZED TO MODEL TEST DATA

1.6

1.4

QI 1.2 =->-fll 1s:: 0..... fl)

~ .§ 0.8

ct § z 0.6

0.4

0.2

4

·--·

-~

.

I I (

~

' ' ' ' ' '

1 2 3

Drill Ship#

DRILL SHIP - WIND COEFFICIENT - BEAM SEAS VALUES NORMALIZED TO MODEL TEST DATA

-

-

1.4

1.2

QI

.E 1> iiic: 0 'iil 0.8 al .§'?§ 0.6

z

0.4

0.2

I I

I

"'

'I ' ' ' ' 1 2 3 4

Drill Ship#

DRILL SHIP - CURRENT COEFFICIENT - HEAD SEAS VALUES NORMALIZED TO MODEL TEST DATA

2.2 --,-------·-----------·

• 2 1--·---------·-f------­

1.8 -l--- --+-------------+

<I.I:::s 1.6 -f-------f->'iii l.4 ­s:: 0..... ~ 1.2 <I.I

•.§ I

I'.? 1§z 0.8

0.6

0.4

0.2

1 2 3 4

Drill Ship#

DRILL SHIP - CURRENT COEFFICIENT - QUARTERING SEAS VALUES NORMALIZED TO MODEL TEST DATA

1.8

1.6

1.4 (II

::I 'iil -::> 1.2

Ill

§ "!il I

~ .§ Cl 0.8

§ I

z 0.6

0.4

0.2

-

• •

[I I I)

1'i

' ' ' I . ' 1 2 3 4

Drill Ship#

-

DRILL SHIP - CURRENT COEFFICIENT - BEAM SEAS VALUES NORMALIZED TO MODEL TEST DATA

•

I~

'' ' 2 3 4

Q)

::i

2

1.8

1.6

<ii 1.4

> ..... !'IIc: 1.2.s (I)

c: Q) 1 .§

-

8 § 0.8

z 0.6

0.4

0.2

-

•

I)

I

-

I

' ' '

~

•

I

Drill Ship#

WAVE-DRIFT FORCE AND WF/LF MOTIONS

1. DATA SOURCE : FPS 2000 PROJECT

• A TURRET-MOORED TANKER

• RESULTS FROM SEVEN ORGANIZATIONS

2. SCOPE OF COMPARISON

RELATIVE WAVE-FREQUENCY CONSISTENCY

• SURGE FORCE GOOD

• SURGE MOTION EXCELLENT

LOW-FREQUENCY

• DRIFT-FORCE SIGNIFICANT COEFF. VARIATION

• LFMOTION WIDESPREAD

I____

I .... I ·-u­. I r---i I . I I I 'I

0.0 0. 1 0.2 0.3. OA O.!J 0.G . 0. 7 0.0 O.D '1.0 1.1 1.2 1.3 1A

. Frequency, cu (rad/sec)

COMPARISON OF WAVE FREQUENCY SURGE RAO

1.00 -y

O.GO "-~• '-..

0

r:­

(J 00 -1--' l

S~fRlJClJJf{I~: 'I'l::is ,,---,--------,......---,

0.1

0 .40 -i--·--·--·--· ­

]0 -1--1--l--0\c--1--1--1--•---- •-·-·•··

l!l Inst 02 (') Inst 03 6 .Inst 04· )( Inst 05 --1 ...

<!> Inst 06 1' Inst 09

--- Mean -1--1--•--· ­ ....................... Mean-1 •sl.dev.

Mean+ 1 *s I.de'!. .. I

o css nc

0.20 -1--1-1-1--1-\. ·-···--··'··--- - ·---..:, -.......,.•.... ' ... ·-· ­

. . , -,-:-;.:....·~·~ID~. 1· I I 11I ' ' · .·· ... rn~<.:J.:._.._,.. · I I ' \ I__;·· -~41~........

Source: FPS 2000 Project Turret Moored Production Svstem (TPS)

--

<(" rir1 ·r1° U ,f'l 1fJ1D 1""' • 1:'.'.> .U. Jr{ \1...,1 \l .!!.~,,. J.:!.t • 1'l:;;S O.GO .,

-

I

c--··--,.-- ­c1 lnsl 02,,iz, Q:> Inst 03 6 Inst 04 x Inst 05 ··-·- ­<!> Inst 06

0.50 -1--1-1---1 i\·

--- MeanOAO ·•--•---· ­ ·················--· Mean-1 •st.dev.

d_J ·············· Mean+ 1 *Sl.dev.

~ 0.30 _____!_\!__· .;:~\-! · 1 1 · o cssnc'i5 I .·~ i '~l-.. -- ­ --·--·--··-··--·

" ...0.20 -1--1--1--; 1 1 --- -:~J:.::b~:::_l ·,.~_-1-1-1-.·-·

····. t);"·. .. :.--.....~.........!....... ..I . .. .. .0.10 -l-!--1--'-----'- - ---- _......c. ;::­'--1.....;,.._J_·I I . . . . ...I . - .....

··~···II I ' 0.00 -I----.--1 . --1--1--1 -,

0.0 0.1 0.2 0.3 OA 0.5 O.G 0.7 0.0 0.9 1.0 1.1 1.2 ·1.3 1.4 . Frequency, CJ (rad/sec)·

COMPARISON OF WAVE FREQUENCY SURGE FORCE

Source: FPS 2000 Project Turret Moored Production Svstcm (TPS)

-<!> Inst 06 0.30 -I 1' Inst 09 -1-­ ---:/­ -

it:."' ,.tf"' ir-~ lJ{'' 1; J · ;:i EC1' • 'T' VJ> ~ ,::> JI. A't. .I 11.. ~.\. • ]. ,[ ,_;1 1O.~)O j Inst 02 I I l!J r-'l I I I I I Il'I

ci Inst 0.3

OAO -I A Inst 04 -1-1-1-···1·~-1---·1-·--•---•--•-·--. · x Inst 05 · · .· ······· \.

---\--·1--1--1--1-··- ··

- Mean .. · IJ ·. .................... Mean-1 •sl.dev. .: ei t @ ··· ·········· ······· ....... . J t .... I-~.· ·,- ,) ­ - '--><­ --.Jl:::.--• --- - ­ ----·--·.t,; 0.~0 .............. Mean+ 1 *Sl.dev. ·. "' - <!> <•

()()l ,'i' (~o cs snc ri .. , i 1•1 , 1

f"!··:-..; ·... A · " .s-­ 13

(

1'~,, tilm •

Li~ 0.10 --1-1-1-~- ~----·--.i.---1- ~~--('I x ,. ..... :\ ' .·/

(11. I d ... 0 •.••..•... ......... "' I U .,, .............. ··········· ······ .....0.00 -1-,-1- ~11 ---·;·--·~-·=.::::.==-·- ~~--·. I . .

'\ j. /. - . \ . " -0.10-1-1-11--.l,:l~t~-·-. ~--·----·----.--~--:1-·..

' ' .-0.20 --I --1 I -.-.r ­0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.0 0.9 1.0 1.1 1.2 1:3 1.4

Frequency, w (rad/sec)

COMPARISON OF WAVE DRIFT FORCE COEFFICIENTS

Source: PPS 2000 Project Turret Moored Production Svslcm (TPS)

(/J 90

~ (J t'1.. B

"l '"d (/J 7 N 0 a 0 6 ,.,......_,

i (/J

E "---" 5

>< (l)

~ 2" ~ t'1 '"d :J0 ~ (/) ~ 3

2

o ' a:::::::: c;::::;; p•;:"·; x; ..... ;., ):!"·· .. ;: 11;·;..:· d....... I

04 05 06 18 24 28

Institution No:

TPS. Motion response in design condition (H = 15.5 111). Slnndnrd de\'intions of first order n\'F) and lo'~' frequency (LF) 111otion response in st11·gc. I 0 degrees heading to the waves

VESSEL LF DAMPING GVA 5000 4-COLUMN SEMISUBMERSIBLE

I. CO.MPUT A TIONAL METHOD

• MIT/DnV ns FOR TLP • LIMITATIONS

- 4-COLUMNS - PONTOONS IGNORED

• PRINCIPAL INVESTIGATOR: PAUL SCLAVONOUS

2. STUDY MATRIX

• SIGNIFICANT WAVE HEIGHTS (P-M): 30', 40', AND 50' • WAVE HEADINGS: 0°, 22.5°, AND 45° • SYSTEM STIFFNESS (KIPS/Ff): 5, 10, AND 20 • WAVE-DAMPING AND VISCOUS-DAMPING

3. A DESIGN CASE: GOMEX 10-YEAR STORM (ASSUMING K = 10 KIPS/Ff)

DAMPING(% OF SYSTEM CRITICAL) HEAD SEA BEAM SEA

WA VE DAMPING 2.8% 2.8% VISCOUS DAMPING 1.7% 4.5% TOTAL 4.5% 7.3%

.. x

y

d=52'-6"

1=200' ·-----;,>

1=200'

>

FIG. i

IE'- =. 0..,,. 0 0...II 0 II II

• II 0

::i: cQ. (.) .ll:.­

0

§ N

0

(1)

e1 § ::i (/)

c::. ·--0

0 :E = ·c: 0

-3: 0 (/) 0

0 0 0,,,. ,...,

[ij] - x

-

• • •

• • •

SEMI-SUBMERSIBLE/FPS (GV A 5000 CLASS) LF SURGE WAVE DRIFT DAMPING HEADING ANGLE= 0.0 DEGREES

6.0

~ ''"' 5.0

~ 0 4.0

-e ·.;:::·i:: 3.0 0-­u s ~ 2.0 ~

VJ

15 1.0

~ !computed by: Professor Sdavonous of MIT

0.0

~ w ~ ~ ~ ~

Significant Wave Height (ft)

r=---==-k=s -0-- k=lO -·- k=20 I

55

• • •

5.0 ~

4.5 b() . s a- 4.0

0 3.5-~ 3.0 ·~ ·i:: 2.5 u E 2.0 .l!! ~ 1.5

CJ)

""' 1.00

~ 05

SEMI-SUBMERSIBLE/FPS (GVA 5000 CLASS) LF SURGE WAVE DRIFT DAMPING HEADING ANGLE =22.5 DEGREES

··-~~-~~~~~-~-~~~~~~-~~-· .

1computed by: Professor Sclavonous of MIT o.o -r

25 30 35 40 45 50

Significant Wave Height (ft)

I-·-k= 5 --0-- k= 10 -·-·- k-:~1

55

• • •

SEMI-SUBMERSIBLE/FPS (GV A 5000 CLASS) LF SURGE WAVE DRIFT DAMPING HEADING ANGLE =45.0 DEGREES

3.0 ~~~-~------~~-~~--------~~-~-~~--~-~---,

Oil

·s.=2.5

El !U

-Cl 2.0

G :0·r:: 1.5 u El GI-a 1.0

(.()

0 0.5 ""' ~

1con1puled by: Professor Sdavonous of MIT ~~~+-~~~~~--t~~~~~~-t-~~~~~~--10.0

25 30 35 40 45 50 55

Significant Wave Height (ft)

[-·-k=S -0--k=lO -·-k=20 I

• • •

SEMI-SUBMERSIBLE/FPS (GV A 5000 CLASS) LF SWAY WAVE DRIFT DAMPING HEADING ANGLE= 0.0 DEGREES

1.0~·

00 0.9 .. . •· .i::.....a0.8

<UCl 0.7-e o.6 ..... ....·i:: 0.5 u s 0.4 Cl>.... ~ 0.3

CJ) ..... 0.2 0

~ 0.1

computed by: Professor Sdavonous of MITo.o ..125 30 35 40 45 50 55

Significant Wave Height (ft)

1--- k =5 --0- k =10 -·- k =20J

• • •

SEMI-SUBMERSIBLE/FPS (GV A 5000 CLASS) LF SWAY WA VE DRIFT DAMPING HEADING ANGLE =22.5 DEGREES

J.6.------------------------------------------.

.5btl 1.4

S'ns 1.2

0 ~ 1.0 v..... u·I:: 0.8

s(II 0.6

i Cf} 0.4

0 ~ 0.2 ""'

0.0

. -~~-~~~~

romputed by: Professor Sdavonous of MIT I I

25 30 35 40 45 50

Significant Wave Height (ft)

r=:-=k-=; -~~=~0-==;=-;;1

55

SEMI-SUBMERSIBLE/FPS (GVA 5000 CLASS) LF SWAY WAVE DRIFT DAMPING HEADING ANGLE =45.0 DEGREES

3.0 .--·~~~~-~~~~~~~~~~~~~·~~~~~~~~~~~~~~~~~~~~~~~~~~

Oil

·[ 2.5

El "' -Cl 2.0

G 'Jj;s 1.5

El 2 1.0 ~ (/)

~ 0.5

ti!?.

0.0

··~~~~~~~~~~~~~~~~-· .

. ·~~~~~~~~~~~~~~~~~·

computed by: Professor Sdavonous of MIT

30 35 40 45 50 55

Significant Wave Height (ft)

I=--·-- k = s -·- k = 20 I-0-- k = 10

25

SEMI-SUBMERSIBLE/FPS (GV A 5000 CLASS) LF SURGE VISCOUS DAMPING

HEADING ANGLE= 0.0 DEGREES

3.0

Cl) i::·s.. 2.5

a Ill

0 2.0 ...... G..... ....·i:: 1.5 u a ~ 1.0 ~ t/)

""'0 0.5

If:.

0.0 !derived from computations by: Professor Sdavonous of MIT

I I I I

25 30 35 ' 40 45 50 55

Significant Wave Height (ft)

i--=-~=- k =5 -0­ k =JO -· ­ k =20 I

• • •

SEMI-SUBMERSIBLE/FPS (GV A 5000 CLASS) LF SWAY VISCOUS DAMPING

HEADING ANGLE =90.0 DEGREES

8.0 ,----------------------------------------,

.500 7.0

S­ta 6.0

0 ~ 5.0 u.... ....c4.o.

ElQJ 3.0

~ (/) 2.0 '+-< 0 ~ 1.0

derived from computations by: Professor Sdavonous of MIT 0.0

25 30 35 40 45 50 55

Significant Wave Height (ft)

[ =--:_··- k = 5 ---0--- k =10 -·- k =2~

VESSEL LF DAMPING SEDCO 700 SEM!SUB:MERSIBLE

1. COMPUTATIONAL:METHODS

• MORA 3-D PROGRAM: WAVE DAMPING • LINEARIZATION: VISCOUS DAMPING • RATIONALIZED PROCEDURE: CURRENT AND WIND • CO LINEAR CORRELA TED WIND-WA VE-CURRENT

2. STUDY MATRIX: COMP ARABLE TO GV A 5000

3. A DESIGN CASE: GO:MEX IO-YEAR STORM (ASSUMING K = 10 KIPS/FD

DAMPING C% OF SYSTEM CRITICAL) HEAD SEA BEAM SEA

WA VE DRIFT DAMPING 0.2% 0.2% VISCOUS DAMPING

• NOCURRENT 1.7% 2.5% • 1.8-KNOT CURRENT 13% 22%

AERODYNAMIC DAMPING 2.7% 1.9% C72-KNOT WIND) TOTAL 5-16% 5-24%

• LF MAX. MOTION: 13 FT. • LF PERIOD: 90 SEC. • LF MAX. VELOCITY: 0.9 FT/SEC (0.5 KTS) • MOORING SYSTEM STIFFNESS: 12 KIPS/FT

(1000' WD)

CHAPTER 4 · MORFRED

oncoming waves and decreases during the half-cycle where the structure tends to move with the waves thus giving rise to a damping force. Based on the work done in a full cycle, the wave damping coefficient may be related to the gradient of the mean drift force as

2.Jtf dFfl b,(f) - _cosf3­

g df.

2.Jtf . dFf'__;:_srnf3­g df.

where

F,(2) =the mean drift force in the i·direction.

f =wave frequency.

f, =wave encounter frequency.

g = acceleration of gravity.

f3 = wave incidence angle.

b,(f) = the i-the component damping coefficient.

The mean value of the wave damping for a wave spectrum is given by

m b (f) b - 2[S(f) .' df

"""' (H/2.)2

The wave damping coefficient b1(f) is proportional to the wave amplitude squared, i.e., (H/2)2,

since b1(f) is proportional to the mean drift force.

The viscous damping is computed by the same linearized method as used in the response to wave frequency. The total mean damping is given bythe sum of the wave damping and viscous damping, bu. =b...,., + b....

The drift response analysis disregards the yawing motion and deals only with motion in the

4.6

Source: MORA Manual

ASSUMPTIONS/APPROXIMATIONS

I. COLINEAR/CORRELA TED WIND-WA VE-CURRENT

WIND CURRENT Hs SPEED VELOCITY 20' 36KTS 0.6 KTS 30' 72KTS 1.8 KTS 40' 108 KTS 3.0 KTS 50' 132 KTS 4.4KTS

2. API RP-2P LF MOTIONS

LF RMS = (REF. RMS) .JI 8 I K

LF SIG. = 2*(LF RMS)

LF MAX= 3*(LF RMS)

3. API RP-2P WF MOTION RAOS

WF RMS BY SPECTRAL ANALYSIS

WF SIG =2*(WF RMS)

WF MAX = 1.86*(WF SIG)

COMPUTATIONAL METHOD

1. LINEARIZED LF VISCOUS DAMPING (CLe)

8 CLe = - Coe* VLF

31t

Coe= CURRENT FORCE COEFFICIENT

Vu= LF VELOCITY AMPLITUDE

2. EFFECTS OF A STRONG COLINEAR CURRENT

FoRAG =Coe [VCURR+ VLF (t)]2

FoAMPL.~G = (2*Coe*VcuRR) VLF (t)

CoAMPING = 2*Coe*VeURR

CeRmeAL = 2.J(M + A) K

DAMPING RATIO = CoAMPING/CCRITieAL

3. EFFECTS OF A STRONG COLINEAR WIND (SOURCE: PROFESSOR VICKERY OF U. OF WESTERN ONTARIO)

CoAMPING = 2*Cow*VwiNo

Cow = WIND FORCE COEFFICIENT

VESSEL/MOORING PARTICULARS SEDCO 700 SEMISUB.MERSIBLE IN OBLIQUE SEA

MOORING PARTICULARS 3000'WD IOOO'WD 300'WD NO. OF LINES MOORING PATTERN LINE SEGMENT 1

(FROM ANCHOR) LINE SEGMENT 2

8 45° SYM.

3" ORQ CHAIN 2000'

3 3/8" WIRE 7000'

8 45° SYM.

3"0RQCHAIN 2000'

3 3/8" WIRE 5000'

8 45° SYM.

3" ORQ CHAIN 4000'

VESSEL PARTICULARS (SLUGS)

MASS SURGE ADDED MASS SWAY ADDED MASS

l.51E+06 5.15E+05 1.28E+06

l.5IE+06 5.15E+05 l.28E+06

l.51E+06 5.15E+05 1.28E+06

MEAN ENV. LOAD 668 KIPS 668 KIPS 668 KIPS

MOORING SYSTEM STIFFNESS(LBS/FD

3700 12200 28800

VESSEL MOTIONS

LF MAX. MOTION* LFPERIOD WF MEAN MOTION (RMS)

22 FT. 160 SEC. 3.3 FT.

13 FT. 90 SEC. 3.3 FT.

9FT. 60 SEC. 3.3 FT.

"' API RP-2P BEAM SEA LF VALVES.

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF SURGE WAVE DRIFT DAMPING HEADING ANGLE= 0.0 DEGREES

0.40 ...------------------------------------------,

00:::.... 0.. ElIll 030 . -

0

'5 -.i::·i:: 0.20

•1~---~----------~,. . u

o-~~~~~~~~--c1---~~~~~~~----n ~ t; >.. 0.10t/)

0 """ ~

Q.OQ +MORA3·DA_N_A_LYS_1s_-t-----~---11---------t~---~----+-~---~--t--

30 35 40 45 50 55

Significant Wave Height (ft)

[-·- k=5 -0-- k= JO -·- k=20 I

25

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF SURGE WAVE DRIFT DAMPING HEADING ANGLE = 45.0 DEGREES

0.15 ~--------------------------------------,

bl) s:::..... ll..

~ 0 0.10 e..... ·1:1 u . ··------~~-~~---~ 0.05

~ U') ·------·----- •...... 0

!ft MORA 3-D ANALYSIS

0.00 r-------t-------+------r-------+-------+-------1 25 30 35 40 45 50 55

Significant Wave Height (ft)

[--------;:-:, 5---0-- k = 10 -·- k = 20 I

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF SWAY WAVE DRIFT DAMPING HEADING ANGLE= 45.0 DEGREES

0.15 ,------------------------- ­

~ ..... c.. s n:I

Cl 0.10

5..... ....·i:: u s2 0.05 ~

(J')

/:) 'f1'.

MORA 3·D ANALYSIS

0.00 25

. ·--------------•

·~~~~~~~~~~~~~~~~-· .

50 30 35 40 45

Significant Wave Height (ft)

r=·= ;:, 5-- -0--- k =10 -·- k =20J

55

• • •

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF SWAY WAVE DRIFT DAMPING HEADING ANGLE= 90.0 DEGREES

050 .---·~-~~~~~~~~~-~~~~~~~~~~~~~~~~~~~~~~~---,

~ .....s0.40 Ill . -~~~~~~~~~~~~~~~~~•

0-~ 0.30 ·.i::·i:: u s 0.20

.l!! ~

tf} ..... 0.10 0

~ MORA 3·D ANALYSIS

0.00 I I

25 30 35 40 45 50 55

Significant Wave Height (ft)

r=·=~=-5 k= 10 -·- k=20 I-0­

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF SURGE VISCOUS DAMPING

(NO CURRENT, LF MOTION ONLY) HEADING ANGLE= 0.0 DEGREES

ESTIMATED BASED ON LINEARIZED CURRENT FORCE COEFFICIENTS 3.00

bl) ;:: 2.50.... --------· .·----- ­s­111Cl 2.00-!5 ~8 1.50 ­

~ .... ~ 1.00

...... 0 ~ 0.50

l ····--···-·--­0.00 +--- - -- -,

30 35 40 45 50 55

Significant Wave Height (ft) r-·- k=S --0- k= 10 -·- k=20 1

25

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF VISCOUS DAMPING

(NO CURRENT, LF MOTION ONLY) HEADING ANGLE= 45.0 DEGREES

.()() ESTIMATED BASED ON LINEARIZED CURRENT IQRCE COEFFlC!ENTS 2

. •.,~~~~~~~~~~~~~-bl) i::·s. 1.60

El 8 ;a 1.20 u....

·'E u El 0.80 QJ

~ '+-I 0 0.40 ~

o.oo 4~~~~~~-+~~~~~~-1-~~~~~~-+-~~~~~~--+-~~~~~~-1-~~~~~---; 25 30 35 40 45 50 55

Significant Wave Height (ft)

1---=-.~ k= 5 -====~-;-==.=k-:;o-1

5.00

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF S\VA Y VISCOUS DAMPING

(NO CURRENT, LF MOTION ONLY) HEADING ANGLE =90.0 DEGREES

ESTJMATED BASED ON LINEARIZED CURRENT FORCE COEFFICIENTS

~ ·s. 4.00 • •

~ •

-5 3.00

·.i::·c: u El 2.00 - ··-~~~~~~~~~~~~~~~~~~~~~~· . (I.I.... (/)

>. ti) ...... 0 1.00

tf'­

0.00 +--~-----+-----~--+-~----f-----~--+-------+---~---1

25 30 35 40 45 50

Significant Wave Height (ft)

r--=-.=-- k =5 ~ -·- = ~o~Ik =10 k

55

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF WIND INDUCED DAMPING

(LF MOTION PLUS WIND) HEADING ANGLE =0.0 DEGREES

ESTIMATED BASED ON MORRISON'S EQUATION (VICKERY MET! 101))8 ··-~~~~~~~~~~~~~~~~~~~~~-

00 7 • r::..... s ~ 6 •0 ..... 5

.........8 ~

4 • ~ 3 ..... :z. •------· ti) 2 '+-< • 0

~ I

0 -t-~~~~-t-~~~~-t-~~~~-t-~~~~-t-~~~~-t-~~~~-1-~~~~-1-~~~~~

20 25 30 35 40 45 50 55

Significant Wave Height (ft)

i-=~=--k:5~i~:/;·~ k= JO kips/ft -•- k ~20kips/ft I

15

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF WIND INDUCED DAMPING

(LF MOTION PLUS WIND) HEADING ANGLE =45.0 DEGREES

B ESTIMATE!) BASED ON MORRISON'S EQUATION (VICKERY METHOD)

bl) 7 . s i::i.s 6

0 - 5

-~ t5 4

~ 3 • -------· ~

U') 2 ..... 0

~ I

0 +------+---~-+--~---if------+-~-~~•-----+----4------<

•

•

15 20 25 30 35 40 45 50

Significant Wave Height (ft)

1-==..=--k-:,~;s/ft --a- k= 10 kips/ft -·-=-~-:-;;;~-;]

55

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF WIND INDUCED DAMPING

(LF MOTION PLUS WIND) HEADING ANGLE= 90.0 DEGREES

g ESTIMATED BASED ON MORRISON'S EQUATION (VICKERY MET! 100)

bl) 7 r::......

S' 6

Q ~ 5 ­

~;s 4

13 ~ 2 0

~ 1

0 +---­ -···-~-- --,---.-.--------~ -------~-----~---·--r--------~

• -----·

15 20 25 30 35 40 45 50 55

Significant Wave Height (ft)

,-=•- k = 5 kips/ft --=:;;:=_-k = 10 kips/It -•- k = 20 kips/ItJ

50

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF CURRENT INDUCED DAMPING

(LF MOTION PLUS CURRENT) HEADING ANGLE= 0.0 DEGREES

ESTIMATED BASED ON MORRISON'S (VICKERY MET! !OD)

•45 00r:: .... 40 p..

~ 35 Cl •;;; 30 u.... .....

·i::: 25 u • a 20 (I.I •.... ti) •;>, 15

{/) ...... 0 10

~ 5

0 I - --·1-- -- -- - --- -- ·r- I' ' 20 25 30 35 40 45 50 55

Significant Wave Height (ft)

1·~~ ~=5-ki;s~ft -n-- k= lOkips/ft -·-=-~~;O~ips/;t I

15

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF CURRENT INDUCED DAMPING

(LF MOTION PLUS CURRENT) HEADING ANGLE= 45.0 DEGREES

ESTIMATED BASED ON MORRISON'S (VICKERY MET! IOD) 70

Oil 60 i:::..... Q..

s 50tU Q-:3 40·.i::·i:: us 30 •

Q.I.... (/J

>. 20t/)

..... 0

if 10

0

•

•

15 20 25 30 35 40 45 50 55

Significant Wave Height (ft)

c=-:-=~-:-;;:;/~ -~ k = 10 kips/ft -·- k = 20 kips/f~I

SEMI-SUBMERSIBLE (SEDCO 700 CLASS) LF CURRENT INDUCED DAMPING

(LF MOTION PLUS CURRENT) HEADING ANGLE= 90.0 DEGREES

SO ESTIMATED BASED ON MORRISON'S EQUATION (VICKERY METf IOD)

70 ­

bl) 60.5

~ •Q 50

]8 40 •

~ •~ 30 <fl •"" 0 ~ 20

10 ~-

0 +--- r-·-~---~------·---------i··----~---------~---------. -­--r- J

15 20 25 30 35 40 45 50

Significant Wave Height (ft)

r=~=-;.-:;;~~~~ft- ~--=- k =10 kips/ft -·- k =20 ~~ps/ft]

55

VESSEL LF DAMPING DRILLSHIP C380' X 70' X 26')

1. COMPUTATIONAL METHODS: REF. SEDCO 700

2. STUDY MA1RIX: REF. SEDCO 700

3. A DESIGN CASE: GO.MEX IO-YEAR STORM

DAMPING(% OF SYSTEM CRITICAL) HEAD SEA BEAM SEA

WA VE DRIFT DAMPING 1o/o 2.9% VISCOUS DAMPING

• NOCURRENT 0.2% 6.7%

• 1.8-KNOT CURRENT 2.3% 26% AERODYNAMIC DAMPING 1.9% 3.4% (72-KNOT WIND} TOTAL 1.6-5.3% 13-32%

• LF MAX. MOTION: 12FT. 22FT. • LFPERIOD: 120 SEC. 80 SEC. • LF MAX. VELOCITY: 0.7 FT/SEC 1.9 FT.SEC

(0.4 KTS) (1.1 KTS) • MOORING SYSTEM STIFFNESS 2.7 KIPS/FT 6.8 KIPS/FT

(1000' WD)

VESSEL/MOORING PARTICULARS DRILLSHIP CL X B X D =380' X 70' X 26')

3000'WD 1000' WD 300'WD MOORING PARTICULARS NO. OF LINES MOORING PATTERN LINE SEGMENT 1 GRADE 3 2.5" CHAIN

LINE SEGMENT 2 2.5" WIRE

Y.ESSEL PARTICULARS MASS (SLUGS) ADDED MASS (SLUGS)

MEAN ENV. LOAD CKIPS)

MOORING SYSTEM STIFFNESS (LBS/FD

VESSEL MOTIONS LF MAX. MOTIONS LF PERIODS (SEC.) WF MOTION (RMS)

HEAD .s.E.a

8 45°

2000'

3500'

8.39E+05 5.88E+04

195

600

20' 210 4.9'

BEAM .s.E.a

8 60°

2000'

3500'

8.39E+o5 5.89E+o5

590

2900

31.8' 120 6.7'

HEAD .s.E.a

8 45°

2000'

1500'

8.39E+o5 5.88E+o4

195

2700

12.5' 120 4.9'

BEAM .s.E.a

8 60°

2000'

1500'

8.39E+o5 5.89E+05

590

6800

21.8' 80

6.7'

HEAD .s.E.a

8 45°

4000'

BEAM SEA

8 60°

4000'

8.39E+05 5.88E+04

8.39E+05 5.89E+05

195 590

7900 21350

8.1' 70

4.9'

13.3' 50

6.7'

• • •

• • •

DRILL SHIP (L x Bx D = 380' x 70' x 26') LF SURGE WAVE DRIFT DAMPING HEADING ANGLE =0.0 DEGREES

1.00 .-~~~~~~~~~~~~~~--~~~~~~~~~~~~~~~~~~~~~~~~~~~-,

bll i::..... P.. 0.75 s 0 -e :rJ·i:: 0.50 u ~ .... ~

U')

.... 0.25 0

~

MORA 3-D ANALYSIS 0.00 +-~-----+-~-----+-----~1-------+-------+-------l

25 30 35 40 45 50 55

Significant Wave Height (ft)

I-·- k = 5 ---(}-- k = 10 -·- k =201

• • •

DRILL SHIP (L x Bx D == 380' x 70' x 26') LF SURGE WAVE DRIFT DAMPING HEADING ANGLE== 30.0 DEGREES

1.00 ~---------------------,

~ ..... 0.. 0.75

~ Cl ...... ~ ..... .....·i:: 0.50 u

....5 ~

(/}

..... 0.25 0

If?

O.OO -\MORA3-DANALYSIS

25 30 35 40 45 50

Significant Wave Height (ft)

[ ·- -k~S --~ k=lO =;:=-;:;I

55

• • •

DRILL SHIP (L x B x D = 380' x 70' x 26') LF SURGE WAVE DRIFT DAMPING HEADING ANGLE= 60.0 DEGREES

1.00

~ .....S' 0.75

111 0-~ .........8 0.50

~ 1,tl 0.25

~

MORA 3-D ANALYSIS

0.00 b~~~·----+-----+-----+-----::~----; 25 30 35 40 45 50 55

Significant Wave Height (ft)

[-=-=-k =5 ----0--- k=10 -·-·-k =2~]

• • •

DRILL SHIP (L x B x D = 380' x 70' x 26') LF SWAY WAVE DRIFT DAMPING HEADING ANGLE =30.0 DEGREES

0.75 ~-------------------------------------.

bl)

.s s t:lIU

0.50

i\l v :;j • •1~~~~~~~~~~~~~~~----

8 i;;.., 0.25 rJJ. ..... 0

~

MORA 3·D ANALYSIS o.oo +------+------+------+------t-------\--------1

25 30 35 40 45 50 55

Significant Wave Height (ft)

I -·- ---0-- k = 10 ---~=~=~~lk = s

• • •

• • •

DRILL SHIP (L x Bx D =380' x 70' x 26') LF SWAY WAVE DRIFT DAMPING HEADING ANGLE= 60.0 DEGREES

2.50 -.---------------------------------------,

b[)r:: 2.00 ­.....

~ 0 ;\j 1.50 n--~-~-~~-~--o-~--~--~-~-:-D v

·..;::·i:: u ~ 1.00 .... ~

Cf1 '+< 0

0.50 ~

MORA J.D ANALYSIS 0.00 +-------l-------+-------"f-------+-------+-------1

25 30 35 40 45 50 55

Significant Wave Height (ft)I- --- -- -- -- ---- -··- --- -] -·-- k = 5 -{]-- k =10 -·- k =20

• • •

DRILL SHIP (L x Bx D = 380' x 70' x 26') LF SWAY WAVE DRIFT DAMPING HEADING ANGLE= 90.0 DEGREES

4.00 ..,--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-,

. -~~~~~~~~~~~~~~~---.... ~ 3.50 -·­

S' 3.00

Ill

-0 2.50

G '.t:·i::: 2.00 u El ~ 1.50

~ (/)

..... 1.00 0

~ 0.50

O.{)() MORA3-DANALYSIS

30 35 40 45 50 55

Significant Wave Height (ft)

r=== k~5 -o-k=lO -•-k=20]

25

• • •

• • •

DRILL SHIP (L x B x D =380' x 70' x 26') LF SURGE VISCOUS DAMPING

(NO CURRENT, LF MOTION ONLY) HEADING ANGLE =0.0 DEGREES

0.30 ESTIMATED BASED ON LINEARIZED CURRENT FORCE COEFFICIENTS

Cl)s:: 0.25.... t:l. E 0"' 0.20-~ ........;s 0.15

~ ~ 0.10

..... 0 ~ 0.05

0.00 -t--~~~~~-r~~~~~-+~~~~~~t--~~~~~-t-~~~~~-t

30 35 40 45 50 55

Significant Wave Height (ft)

r=-·-- k =5 --0- k ~~=-:-= ~=~~1

25

DRILL SHIP (L x Bx D = 380' x 70' x 26') LF SWAY VISCOUS DAMPING

(NO CURRENT, LF MOTION ONLY) HEADING ANGLE = 90.0 DEGREES

8.00 ,.ESTIMATED BASED ON LINEARIZED CURRENT FORCE COEFFICIENTS

• •1~~~~~~~~~~~~~~~~~~~~~. ~~

......= ~ s~

0 ~

~Sm·

~84m i~­~ ~2m 0

~ 1m

o.oo L----r----+----+----~---:::-----; 25 30 35 40 45 50 55

Significant Wave Height (ft)

c------=-.:-: 5~--0- k = 10 -·- k = 20 I

DRILL SHIP (L x Bx D = 380' x 70' x 26') LF WIND INDUCED DAMPING

(LF MOTION PLUS WIND) HEADING ANGLE = 0.0 DEGREES

ESTIMATED BASED ON MORRISON'S EQUATION (VICKERY MET! IOD)3

.sco 2.5

a Ill •Cl 2-::!

·.i:: ·i::u 1.5

s ~ 1

£ ""'0 <ft 0.5

-------·•

0 +----~1------+-----t----~+------1--~~-+~~-~>--~~~-<

•

15 20 25 30 35 40 45 50 55

Significant Wave Height (ft)

-•- k =5 kips/ft --o- k =10 kips/ft -•- k 20 kips/ft

DRILL SHIP (L x B x D = 380' x 70' x 26') LF WIND INDUCED DAMPING

(LF MOTION PLUS WIND) HEADING ANGLE= 90.0 DEGREES

S ESTIMATED BASED ON MORRISON'S EQUATION (VICKERY METI IOD)

bl) 7

.s ~ a 6 rd 0 ...... 5 rd

·15·c:u 4

a .!!! 3

» "' (J') 2 ..... Q

~ 1

0

• •

•

•

15 20 25 30 35 40 45 50 55

Significant Wave Height (ft)

l=---- k =5 kips/ft --0- k =10 kips/ft -•- k =20 kips/ft]

DRILL SHIP (L x Bx D = 380' x 70' x 26') LF CURRENT INDUCED DAMPING

(LF MOTION PLUS CURRENT) HEADING ANGLE =0.0 DEGREES

ESTIMATED BASED ON MORRISON'S (VICKERY METI IOD) 4.5

• 4

bO .si 3.5

Cl 3 .. 'B:;:: 2.5 ·i:: u 2 El 2

•~ 1.5

15 1 ­

tf. 0.5

0 +--~---1,___----t------+------+------l------+-----1--------1

•

15 20 25 30 35 40 45 so 55

Significant Wave Height (ft)

( -11- k:5-~~;/~t --o---- k = 10 kips/ft -•- k = 20 kips/ft I

DRILL SHIP (L x Bx D =380' x 70' x 26') LF CURRENT INDUCED DAMPING

(LF MOTION PLUS CURRENT) HEADING ANGLE = 90.0 DEGREES

BO ESTIMATED BASED ON MORRISON'S EQUATION (VICKERY METHOD)

bO 70 .s ll..El 60 Ill t:l - 50~ .... 8.... 40

~ 30 .... ~ ~ 20 0

~ 10

0

•

•

• •

,---- r-- - -~r-- -- '' ' 15 20 25 30 35 40 45 50

Significant Wave Height (ft)

1---- k = 5 kips/ft --a- k = 10 kips/ft -•- ~-=-;O ~i~s/f~ I 55