the utilization of the pendulous motion for deploying subsea hardware in ultra-deep water

The utilization of the pendulous motion for deploying subsea hardware in ultra-deep water

The utilization of the pendulous motion for deploying subsea hardware in ultra-deep water

Francisco E. RoveriPetrobras R&D

Rogério D. MachadoPetrobras E&P

Pedro F. K. StockPetrobras E&P

Maxwell B. de CerqueiraPetrobras E&P

Francisco E. RoveriPetrobras R&D

Rogério D. MachadoPetrobras E&P

Pedro F. K. StockPetrobras E&P

Maxwell B. de CerqueiraPetrobras E&P

17th FPSO Research ForumApril 5th 2006

Smaller subsea hardware and shallow waters: crane barge, crane of SS, AHTS

Previous installation of some subsea hardware by Petrobras

Previous installation of some subsea hardware by Petrobras

Crane barge and slings – 420 Te/620 m (1995)

Previous installation of some subsea hardware by Petrobras

Previous installation of some subsea hardware by Petrobras

MODU/drilling riser – 240 Te/940 m (2001)

Previous installation of some subsea hardware by Petrobras

Previous installation of some subsea hardware by Petrobras

Rotary table

Axial dynamics

Interface loads

Sheave Method – 175 Te/1900 m (2002)

Previous installation of some subsea hardware by Petrobras

Previous installation of some subsea hardware by Petrobras

The Pendulous MethodThe Pendulous Method

Disadvantage of wire rope: self weight + axial resonance (DAF)

Alternative: special construction vessels (scarce and high daily rates) installation costs prohibitive

Synthetic fiber rope issues to be solved: bending and heating + axial resonance (w/o heave compensation)

Challenge of deployment in increasing WD(250 Te payload, 2000-3000 m WD)

Challenge of deployment in increasing WD(250 Te payload, 2000-3000 m WD)

nat

a

nat w

1

em

ΜΜ

Κ

2πΤ

L

(EA)K equiv

K

M, Ma

K

C

prescribed vertical displacement (Xo)

)f(Lw

wdeployed

nat

frequency ratio β

0

1

2

3

0 1 2 3

w/wnat

DA

F

L = 0 ... Ltotal

Transportation vessel Overboarding

Hangoff Pendulous Motion

The Pendulous MethodThe Pendulous Method

Conceived to overcome the above constraints (DAF1)

Utilization of the Pendulous Motion

Utilization of two workboats

Distance between vessels 80% of cable length

Installation cable, from subsea hardware: wire rope with DBM, polyester and chain

Due to drag the pendulous motion will be very slow

The Pendulous Method (cont.)The Pendulous Method (cont.)

0

1

2

3

0.0 0.5 1.0 1.5 2.0 2.5 3.0

DAF (displacements)

Amplitude of dynamic force (KXo multiplier)

damping ratio ξ = 0.20

frequency ratio w/wn

working region

chainpolyesterwire rope

polyester

wire rope and DBM

slings

manifold

General system configuration (side view, just after release)

General system configuration (side view, just after release)

materialMBL (Te)

Diam. (mm)

length(m)

mass (kg/m)

wet wgt (kgf/m)

EA (MN)

chain R4 1097 105 30 222.7 193.8 840

polyester 1250 210 1600 29 7.40 300

wire rope 1000 127 60 57.8 44.7 965

Weight in air: 280 Te

Dimensions: 16.63 x 8.50 x 5.15 m (L x B X H)

CG 3.15 m above base line (CG≡CB)

System componentsSystem components

Equipment of complex topology

Volume of the envelope dimensions: 728 m3

Steel volume: 35.7 m3 (< 5% total volume)

Some assumptions are needed in order to simplify the computer model

1st aproach to concentrate drag and added mass at CG inadequate

improvement center of pressure and spatial distribution of drag and lift forces

Physics of the problemPhysics of the problem

G≡B G≡B

(1) Suspended at

transportation vessel side

(2) Just after release

G≡B

CL

CNCL

CN

(3) Clockwise rotation

G≡BCL

CN

CL

CN

(4) Anti-clockwise rotation

Physics of the problem (cont.)Physics of the problem (cont.)

PROCAP 3000 project• Participation in JIPs: VP2002 (Odim), DISH (phases

2&3)

Conceived in 2003, based on the procedure for installation of torpedo pile

Numerical analyses with Orcaflex to demonstrate the feasibility

Model tests at LabOceano (UFRJ) in 2004

1:1 scale prototype test in December 2005

Development of the conceptDevelopment of the concept

Three distinct phases:

• equipment at the side of transportation vessel

• pendulous motion

• equipment supported by installation vessel

Some results of numerical analysisSome results of numerical analysis

polyester

wire rope and DBM

chain

manifold

installation vessel

Configuration 10 minutes after releaseConfiguration 10 minutes after release

Cable effective tension, installation vessel side

Cable effective tension, installation vessel side

0

500

1000

1500

2000

2500

0 250 500 750 1000

time (s)

Eff

. te

nsio

n (k

N)

Manifold rotation (deg)Manifold rotation (deg)

0102030

0 400 800 1200

Time (s)

Rot

atio

n (d

eg)

1000_sec.avi 60_sec.avi

Model tests at 1:35, 1:70 and 1:130 scales for manifold #2 – excessive rotations detected in some cases

Model testsModel tests

Decision to build and install a 1:1 prototype for qualification of the method and installation procedure

1:1 Prototype test1:1 Prototype test

increase of sling forces at start

• additional buoyancy to the distributed buoyancy modules

improvement of hydrodynamic stability

• dead weight at the equipment bottom – lowers CG

• a more adequate equipment geometry, e.g., vertical or near vertical (slightly slanted) panels around it

Mitigation of excessive rotationsMitigation of excessive rotations

Construction of Roncador MSGLs #2 and #3 (1850 m WD) awarded to FMC

Pendulous Method to install MSGLs #2 and #3 Pendulous Method to install MSGLs #2 and #3

Utilization of conventional spread

Allow deployment of heavy equipment in ultra deep waters

Attenuation of axial force, prevents resonance

Cost effective compared to utilization of specialized installation vessels or rigs (about 30% cost reduction)

Needs improvement on control of rotations at start

ConclusionsConclusions