PIPELINE INSTALLATION ANALYSIS REPORT

PIPELINE INSTALLATION ANALYSIS REPORT

Z12/112996-ENG-RPT-00003 Rev 02 11.08.2016 Page 1 of 30


Z12/112996-ENG-RPT-00003. Rev 02 Client: LOTOS PETROBALTIC S.A. Project Number: Z12/112996 Project Name: B8 GAS PIPELINE INSTALLATION ENGINEERING

Date Revision Description of Revision Prepared Checked Approved

11.08.2016 02 Issued for Construction M. Bowie G. Cowie A. Cowie

Sheet 1 of 3

DOCUMENT COMMENT SHEET

CLIENT: Lotos Petrobaltic PROJECT : B8 Gas Pipeline Installation

Engineering Date : 13.06.2016

Comments : The response to : Installation Engineering Report Document

Document Type : Report

Document No.: Z12/112996-ENG-PT-00003 Revision : 00 Date : 10.06.2016

Document Title : Pipeline Installation Analysis Report

Received by : M. Maciejewski Date : 13.06.2016 Transmittal No. CSL-OPS-P422-DTN-004

Item Reference Comment Comment By

Contractor’s Response

1. Section 1.2 Objective

First paragraph reads “The objective of this document is to review the process of laying the 4” coil tubing pipeline,” Pipeline is 4.5”OD, please add ND or use OD

A. Wojcikowski

(20.06.2016)

Noted and will correct to use 4.5”OD

2. Section 2.4 Stinger Design

Second paragraph reads “The roller box arrangement must be such that they do not risk damage to the coating under the loads from the pipelay analysis.” LPB question is, how to arrange this for protecting coating from side loads, any special material for rollers (e.g. Teflon) or another polymer?

A. Wojcikowski

(21.06.2016)

Text amended to “The roller box arrangement must be such that they do not risk damage to the coating under the loads from the pipelay analysis. The rollers must rotate freely and contact surfaces consist of a material which has minimal risk of coating damage. The pipe should not contact any surface which is fixed and cannot move relative to the pipe, unless it can be demonstrated that coating damage will not occur.”

3. Section 3.1 General

Third paragraph reads “A preliminary dynamic analysis is performed to determine typical limiting sea state for pipelay based on the pipe behaviour, although the limits will require details of the proposed vessel to be confirmed.” LPB asks whether detailed dynamic analysis will be prepared by Contractor later on or for this purpose as noted is it sufficient to determine sea state limitations?

A. Wojcikowski

(21.06.2016)

For clarity text changed to:

“A preliminary dynamic analysis is performed to determine the typical limiting sea state for pipelay based on the pipe behaviour and loadings / moment imparted onto the pipe.

The selected Installation Contractor shall perform a full dynamic analysis based on the actual vessel proposed and final stinger design, confirming the pipe loadings and limiting sea states for installation.”

Sheet 2 of 3



4. Section 3.3 Effect of Zap-Lok™ on Normal Lay

Third paragraph reads “With reference to the analysis output below, it can be seen that the stress increase at the Zap-Lok™ joint ends is relatively low, with the stress across the main part of the joint, significantly less due to the double wall thickness.” Was this analysis prepared for CTP (Coiled Tubing Pipeline) or anther kind of pipe? Maybe this behaviour can be quite different for CTP, when analysis did for pipe according to API 5L?

A. Wojcikowski

(21.06.2016)

The behavior of the pipe at the joint is identical between CTP and API 5L in the absence of any bending and ovality. The ovality may affect the bending capacity slightly; however the bell forming process removes some of this. For the purpose of the Orcaflex analysis this is a global analysis to determine the effect of the rigid section assuming no smooth transition from the joint area to the pipe.

5. Section 3.4 Start-Up

General comment. Please add information that LPB have to pick-up buoyancy buoy with wire attached to pipe on the bottom.

M. Maciejewski

(21.06.2016)

Noted and will amend relevant document section accordingly.

6. Section 3.4 Start-Up

Second paragraph reads “The first stage involves recovery of the HDD end, which with reference to the recovery table in Appendix A, should be performed with a constant A&R winch line pull of approximately 1 tonne.” Does this mean all winches need to have wire load indicator with scale? Please answer, if other equipment needs load indication, please let us know?

A. Wojcikowski

(21.06.2016)

All winches should have a load readout; however their accuracy at low loads must not be accurate.

To be accurate in the measurement, a loadcell may be attached to the diverter sheave location.

7. Section 3.6 Abandonment & Recovery

Third paragraph reads “During detail engineering the required tensions for each abandonment depth may be defined to a greater level of accuracy but are expected to be in the region of 1 – 1.5 tonnes.” Is detailed engineering required? Maybe installation manual with safety procedures and working procedures will cover this mentioned by Contractor phase?

A. Wojcikowski

(21.06.2016)

Noted and wording amended. The Installation Contractor should perform this as part of the Installation Engineering and insert the tensions required in their Offshore Procedure.

8. Section 3.8.3 Conclusion

General comment. From conclusion point of view, in LPB opinion it’s good to add information that DP vessel is required instead of Anchor Mooring vessel. Please if in next document particular information won’t be written as well or combined in shallow water region?

A. Wojcikowski

(21.06.2016)

Noted and wording amended.

Re-numbered to section 3.8.4

9. Section 4.1 Stinger

First paragraph reads “The stinger should a minimum of approximately 40m radius and 30m length in order to maintain the pipeline within its yield strength during laying.” Please add this information into document RPT-00005, section 3.11

M. Maciejewski

(21.06.2016)


10. Section 4.1 Stinger

Third paragraph reads “The spacing between roller boxes should be in the region of 5m. Spacing’s greater than this may increase the local bending moment on the pipeline due to the larger span between roller boxes.”

Please add this information into document RPT-00005, section 3.11

M. Maciejewski

(21.06.2016)


Sheet 3 of 3



11. Section 5.0 Weather Limitations

Second paragraph reads “The pipeline limitations can be determined by full dynamic analysis once the installation vessel is known; however indications are that the pipeline is susceptibility to direct wave action and movement in the shallower water sections.” LPB suppose that potential installation vessel was presented during this document preparation, wasn’t it?

A. Wojcikowski

(21.06.2016)

Proposed change for clarity is as follows:

“The pipeline limitations can be determined by full dynamic analysis once the Installation Contractors proposed vessel is known. The response of the vessel is dependent upon the hull profile, beam, working draught, length and stability based on the deck load it carries.

Indications are however that the pipeline is susceptibility to direct wave action and movement in the shallower water sections. This is independent of the vessel motions, but a function of the catenary profile, stinger design and configuration. Indication as that the limiting sea state will be in the region of Hs 1m to Hs 2m, subject to the wave heading and period.”

12. Section 6.0 Temporary Stability Requirements

Fifth paragraph reads “In the shallow water of 14m the pipeline is very sensitive to the wave period and height and thus may be unstable in relatively benign conditions.” For this reason, LPB is going to use mattresses to protect left pipeline from November till April 2017, after that in spring recovery of abandoned pipe will start.

A. Wojcikowski

(21.06.2016)

Noted and will add additional suggested wording into this section

13. Appendix A – Lay Table

Normal Lay Analysis Table – 14m water depth results for 98m layback distance. LPB asking is it recommended parameters to keep and results, does it have any margin? Especially for this water depth region.

A. Wojcikowski

(21.06.2016)

There is no margin or factor of safety applied to the calculated footprint within the Lay Analysis table.

14.



REVISION RECORD SHEET

Date Revision Status Reason for Change(s)

11.08.2016 02 IFC Issued for Construction

01.07.2016 01 IFA See attached comment sheet(s)

10.06.2016 00 IFK Issued for Review

TABLE OF CONTENTS

1.0 INTRODUCTION ........................................................................................................................... 3 1.1 General .................................................................................................................................................. 3 1.2 Objective ................................................................................................................................................ 3 1.3 CODES & STANDARDS ............................................................................................................................ 3

2.0 PIPELAY LIMITS ............................................................................................................................ 4 2.1 Pipeline Stress ....................................................................................................................................... 4 2.2 Tensioner Load ...................................................................................................................................... 4 2.3 Minimum Pipeline Tension .................................................................................................................... 4 2.4 Stinger design. ....................................................................................................................................... 4

3.0 LAY ANALYSIS ............................................................................................................................... 5 3.1 General .................................................................................................................................................. 5 3.2 Normal Lay ............................................................................................................................................. 5 3.3 Effect of Zap-Lok™ on Normal Lay ......................................................................................................... 7 3.4 Start-Up ................................................................................................................................................. 9 3.5 Laydown .............................................................................................................................................. 10 3.6 Abandonment & Recovery .................................................................................................................. 10 3.7 Effect of Current .................................................................................................................................. 11 3.8 Preliminary Dynamic Analysis .............................................................................................................. 12

4.0 LAY SYSTEM REQUIREMENTS .................................................................................................... 15 4.1 Stinger.................................................................................................................................................. 15 4.2 Station Keeping System ....................................................................................................................... 15 4.3 Tensioner ............................................................................................................................................. 15

5.0 WEATHER LIMITATIONS ............................................................................................................ 16 6.0 TEMPORARY STABILITY REQUIREMENTS................................................................................... 17 APPENDIX A – Lay Tables ....................................................................................................................... 18 APPENDIX B – Dynamic Analysis Results ............................................................................................... 27



1.0 INTRODUCTION

1.1 General

Lotos Petrobaltic are planning an offshore gas pipeline which will connect a production platform located on the B8 field to a combined heat and power plant (CHP) situated onshore in Wladyslawowo. Prior to being transported in the pipeline the natural gas will be separated from the crude on the production platform. The platform is located in the Poland exclusive economic zone (EEZ) in the Baltic Sea. The B8 field spans an area of 387.1sqare km which was defined in the Concession No. 1/2006 on 5th September 2006 and amended by the Minister for the Environment No. DGiKGe-4770-69/4579/09/MO on 26 October 2009.

1.2 Objective

The objective of this document is to review the process of laying the 4.5” OD coil tubing pipeline, defining the laying parameter and quantifying the effect of the Zap-Lok™ connection on the laying operation. The document does not address the Zap-Lok™ connection procedure or the vessel deck layout / operations and is instead focussed on the functional requirements of the stinger and vessel to safely lay the pipeline.

1.3 CODES & STANDARDS

DNV-OS-F101, “Submarine Pipeline Systems”, DNV RP-C205 “Environmental Conditions and Environmental Loads,



2.0 PIPELAY LIMITS The limits for pipelay primarily consist of the following aspects.

Maximum pipeline stress, strain or bending moment.

Maximum tensioner load

Minimum pipeline tension.

Pipeline behaviour on the stinger

2.1 Pipeline Stress

The maximum stress in the pipeline should typically be maintained below the yield strength of the material to minimise the risk of residual curvature being introduced into the pipe. Residual curvature can induce torsion in the pipeline which will require to be managed during the joint connection. Code requirements vary for the allowable stress; however, since the limiting yield stress is to minimise residual curvature only, the key criteria for the local pipe in terms of integrity is the buckling capacity.

2.2 Tensioner Load

The tensioner requirement will be determined by the pipelay analysis and tensioner selected on the basis of the loads predicted.

2.3 Minimum Pipeline Tension

The pipeline must be laid under tension; however compressive loads may occur during the operation due to wave action.

2.4 Stinger design.

The pipeline is being laid in an empty condition and thus is very light. The behaviour of the pipeline on the stinger requires consideration to determine what functional requirements are needed from the stinger, i.e. side rollers. The roller box arrangement must be such that they do not risk damage to the coating under the loads from the pipelay analysis. The rollers must rotate freely and contact surfaces consist of a material which has minimal risk of coating damage. The pipe should not contact any surface which is fixed and cannot move relative to the pipe, unless it can be demonstrated that coating damage will not occur.



3.0 LAY ANALYSIS

3.1 General

The pipelay analysis has been conducted in order to determine the pipelay settings, including the stinger length and radius plus the sensitivity of the pipeline catenary to ship motions in the various water depths. The document addresses the normal laying operation firstly in order to determine the required stinger configuration and lay tensions. The start-up analysis will be addressed once these normal lay parameters are determined. A preliminary dynamic analysis is performed to determine the typical limiting sea state for pipelay based on the pipe behaviour and loadings / moment imparted onto the pipe. The selected Installation Contractor shall perform a full dynamic analysis based on the actual vessel proposed and final stinger design, confirming the pipe loadings and limiting sea states for installation.

3.2 Normal Lay

The normal lay analysis is the process of laying the continuous section of coiled tubing. The key aspect to this is determining the allowable footprint of the vessel using various stinger configuration for the different water depth, taking into consideration the pipeline stress and tensions. The footprint assessment has been performed for the following water depths. The pipelay is most sensitive to the shallow depths.

Water depth

Stinger length

Stinger radius

Allowable footprint +/-m

Nominal top tension (tonnes)

Nominal tdp tension (tonnes)

14m 30m 40m +/-1m 1.33 1.18

20m 30m 40m +/-2m 0.96 0.77

30m 30m 40m +/-3m 1.14 0.89

50m 30m 40m +/-7m 1.10 0.72

90m 30m 40m +/-12m 1.63 1.00

90m 45m 40m +/-15m 1.38 0.75

Table 1 - Allowable vessel footprint.

The full results are in Appendix A. The allowable footprint of the ship in 14 – 20m of water is small. The limiting factor if the ship moves too far forward is high tensions. If the ship moves too far back the pipe touchdown will be in compression or the bending stress will exceed SMYS. As the water becomes deeper the footprint increases and the limiting factor for pipeline becomes keeping a positive touchdown tension.



The touchdown tension can be increased by allowing the pipeline to flood during lay, which will increase the tensions by approximately 1.5 – 2.0 tonnes (results not included in this report revision). The footprint in deep water can be increased and thus options to reduce the bottom (tdp) tension can be achieved by use of a stinger extension of circa 15m. This will allow a steeper catenary profile. The range of permissible pipeline catenary profiles is illustrated below in plots from the 14m and 90m water depth simulations. It can be seen that in 14m the catenary is tight and there is little movement possible from the ship. In 90m of water the catenary is steeper and more compliant.

Figure 1 - Pipelay in 14m water depth (range of permissible catenaries)



Figure 2 - Pipelay in 90m water depth (range of permissible catenaries)

It should be noted that the laying of the coil tubing is a continuous process, where-as the connection of the Zap-Lok™ joint is the stage where the ship is stationary. Therefore the laying rate for the pipeline will need to be closely monitored to match the pipeline pay-out rate and ship forward speed.

3.3 Effect of Zap-Lok™ on Normal Lay

The effect of the Zap-Lok™ connection being deployed over the stinger has been assessed by a set of snapshots of the stress in the pipeline as the connections pass over the roller boxes which create the highest stresses. The analysis has considered a Zap-Lok™ pup-piece of 3m in length. With reference to the analysis output below, it can be seen that the stress increase at the Zap-Lok™ joint ends is relatively low, with the stress across the main part of the joint, significantly less due to the double wall thickness.



Figure 3 - Effect of Zap-Lok™ on pipeline stress over stinger roller boxes..

The increase in stress on the pipeline at the Zap-Lok™ interface is estimated to be in the region of 4-5%.



3.4 Start-Up

The start-up of the pipelay is the most sensitive operation, since the ship will be in the shallowest water and this will be the first Zap-Lok™ joint to deploy. The first stage involves recovery of the HDD end, via a pre-laid recovery pennant and surface buoy. With reference to the recovery table in Appendix A, the HDD recovery should be performed with a constant A&R winch line pull of approximately 1 tonne. To monitor this tension a calibrated load cell should be provided on the deck sheave diverter. The ship will have to move back during this phase and hence maintaining the winch in constant tension mode will control the catenary profile and hence pipeline stresses. The critical phase is as the pipeline contacts the roller boxes at the top of the roller, which is where the over bend or the pipe will be formed. The tension in the winch should be increased to approximately 1.3 tonnes to achieve this and pull through the open tensioner. The pipeline recovery is illustrated below with the pipeline approximately 10m from the stinger.

Figure 4 - Pipeline Initiation in 14m water depth.

During the connection of the next pipeline joint using Zap-Lok™, the pipeline will have to be restrained on deck and hence the station keeping requirements of the vessel will be as per the normal lay analysis. The allowable footprint for the nominal 100m layback distance configuration will be circa +/-1m. The initiation of the pipeline with the Zap-Lok™ joint has been addressed in the previous section where the lay of the connection over the stinger introduced a small increase in the stresses. The commencement of laying should maintain a layback distance of approximately 100m to ensure the pipeline stress are maintained within the SMYS plus ensure the pipeline is laid with a positive residual tension.

Touchdown point

Pipeline end



3.5 Laydown

The laydown of the pipeline will be performed in circa 88m water depth. The results of the analysis of the operation are contained within Appendix A. The laydown can be performed using equal ship moves and pay-out length as per the table, whereby the ship moves, for example, 10m as 10m of A&R wire is paid out. Alternatively the pipeline can be paid out, initially with a constant tension of 1.5 tonnes, but reducing as the pipeline exits the stinger and the stresses drop off significantly. The pipeline laydown is illustrated below with the pipeline approximately 10m from the stinger.

Figure 5 - Pipeline Laydown in 88m water depth.

3.6 Abandonment & Recovery

The abandonment of the pipeline at the emptying of the last reel on deck can be performed by maintaining a constant tension on the A&R winch as the ship moves forward The recovery of the pipeline is the opposite of abandonment and will involve the same philosophy. The water depth varies along the route and hence the abandonment tension will also vary between approximately 1 – 1.5 tonnes. The Installation Contractor should perform the analysis of these tensions as part of the Installation Engineering and insert the tensions required in their Offshore Procedure.

Touchdown point

Pipeline end



3.7 Effect of Current

The effect of current on the pipeline catenary has been investigated by applying a current of 1 knots perpendicular to the pipeline. As can be seen from the illustrated below looking from above, the pipeline is bent in the direction of the current, which will move the touchdown point off the lay route plus introduce a bending at the stinger tip. To counteract this ship should change heading to keep the pipeline within the stinger plus offset into the current to pull the pipeline back on the laying route.

Figure 6 - Effect of current on pipelay and procedure to correct lay.

The pipelay tensions and stresses are not significantly affected by the ‘crabbing’ of the ship into the current.

X

Y

20 m

OrcaFlex 9.8e: S-NL-4-30m - current.dat (modified 14:38 on 31/05/2016 by OrcaFlex 9.8e)Azimuth=270; Elevation=90Statics Complete

Pipeline route Moved by current



3.8 Preliminary Dynamic Analysis

The preliminary dynamic analysis has been performed to assess the sensitivity of the pipeline to the vessel motions, both in terms of the tensions and any compression observed, but also the impact on the pipelay stresses. The most critical case of 14m water depth and 90m water depth has been assessed. Regular waves have been used for the analysis and given the laying direction being predominately in a Northerly direction waves have assumed as reaching the vessel as quartering head seas.

3.8.1 14m Water depth

The plots of pipeline stresses as a result of the following wave conditions are given in Appendix B.

Wave height 2m, period 5 & 7 seconds

Wave height 4m, period 5 & 7 seconds The response is highly dependent upon the wave height and period which in turn is subject to and very sensitive to the vessel used. In general, the pipeline stresses are controlled by use of a stinger in the upper part, with the most dynamic section, where the pipe departs the stinger seeing greater stress variations. The sagbend or section from stinger to seabed sees increasing fluctuations in the stresses as a result of waves passing and ‘lifting’ the catenary, due to the pipe being relatively light compared to the cross-sectional area presented. The pipe tension at the top of the stinger is also plotted for the most onerous case, which illustrates the potential for the pipe to go into compression in severe weather, plus very high snatch loads up to 4 tonnes (40kN).

Figure 7 - Top tensions in quartering sea H4m, T7s

OrcaFlex 9.8e: S-NL-4-14m-H2m-T5s.dat (modified 10:28 on 01/06/2016 by OrcaFlex 9.8e)

Time History: Line13 Effective Tension at End A

Time (s)2520151050-5

Lin

e13

Effe

ctive T

en

sio

n (

kN

) at

End

A

50

40

30

20

10

0

-10



Part of this behaviour is due to the stinger design, which should consider side rollers to encapsulate the pipeline more. The behaviour of the pipe on the stinger with just V-rollers is illustrated below. The indications from the pipelay analysis are that the limiting heave of the vessel at the stern will be in the region of +/-1m.

Figure 8 - Pipeline behaviour on stinger in extreme conditions.

Note in the above illustrations the roller boxes are red when the pipeline is in contact and light blue when not in contact.

3.8.2 90m water depth

The response of the pipeline in the deeper water is not as severe, mainly due to the steeper angle of the pipe at departure and thus being less influenced by direct wave action. The plot of stress and tension is illustrated in Appendix B for the most extreme case analysis for 14m water depth. The pipeline stresses tend to increase across a greater range on the stinger with a more moderate variation in the sagbend. The pipeline tension varying significantly; however, the movement is lesser than for 14m water depth, plus the pipeline remains within the stinger V-rollers. The indications from the pipelay analysis are that the limiting heave of the vessel at the stern will be in the region of +/-2m.



3.8.3 Minimum laying Radius.

The minimum radius in which the pipeline can be laid on the seabed is determined by the following equation;

Where; T = tension in pipeline at the seabed or touchdown point R = Radius of turn along pipeline route wsub = Submerged weight of pipe µ = Friction between pipe and seabed (nominally 0.5) with reference to Section 3.2 the bottom tensions vary between approximately 0.7 tonnes and 1.2 tonnes assuming pipeline is being laid in the middle of the ship’s allowable footprint. This would give a minimum allowable laying radius of approximately 400 – 800m. The tensions are likely to vary significantly at the shallow water section; therefore, the route should be as straight as possible to minimise the risk of the pipeline being pulled out of its lay curve. As the water depth increases the allowable footprint of the vessel increases also, and thus there is more scope to maintain the lay radii of the route (especially the platform approach) to radii in the region of 500m. Once the curves along the pipeline route have been determined the analysis should be consulted to confirm the feasibility of laying such curves.

3.8.4 Conclusion

The preliminary dynamic analysis has indicated that the pipeline is susceptible to large motions from direction wave actions in the shallower water depths. The stinger design should consider this movement in its selection and design. The limiting installation sea state is discussed later in the document, but generally in the absence of specific vessel being known the limitations for pipelay should be considered as the heave at the stern of the vessel of +/-1m for 14m water depth and +/-2m for the 90m depth. These values can be revised upon identification of the proposed vessel and detailed engineering. The vessel planned to be used for the installation will be Dynamically Positioned (DP); however subject to the station keeping capability of the vessel (i.e. vessel size, number of thrusters and power, etc) and weather during installation, the vessel may not be able to hold station accurately enough to prevent damage to the pipe. Therefore, consideration should be given to a mooring system aft which the vessel can attach to, controlling the position of the vessel more accurately.



4.0 LAY SYSTEM REQUIREMENTS The principal requirements for the lay system is a stinger of sufficient radius and roller box distances to ensure the pipeline stress is not beyond code requirement and such that the maximum expected allowable installation can be sustained with minimal risk to pipe integrity.

4.1 Stinger

The stinger should a minimum of approximately 40m radius and 30m length in order to maintain the pipeline within its yield strength during laying. A tighter radius may be possible; however, this will require closer scrutiny of the bending moments applied to the pipeline and the risk of residual twist in the pipeline from any plastic deformation resulting. The spacing between roller boxes should be in the region of 5m. Spacing’s greater than this may increase the local bending moment on the pipeline due to the larger span between roller boxes.

4.2 Station Keeping System

The station keeping requirement for the shallow water sections are onerous due to the tight catenary required. The installation may have to take place in very benign conditions plus the positioning system should consider the back-up of 2 trailing mooring lines from the ship stern to control the surge of the vessel whilst the pipeline is being recovered and the first couple of Zap-Lok™ joints are being made up. Beyond approximately 30m water depth the station keeping requirements of the vessel are less onerous.

4.3 Tensioner

The pipelay tensions are a function of the catenary profile; however, a maximum tension of approximately 5 tonnes is recommended, since at tensions above this level the pipeline stresses are potentially excessive.



5.0 WEATHER LIMITATIONS The weather limitations for the pipelay operation are a function of a variety of considerations, namely;

Pipeline stress

Pipeline tension

Pipeline buckling resistance in compression.

Stinger seabed clearance.

Vessel response / motions.

Current speeds

Wave height, period and direction

Safe handling operations on deck.

Confidence in the weather forecast.

Ship forward speed. The pipeline limitations can be determined by full dynamic analysis once the Installation Contractors proposed vessel is known. The response of the vessel is dependent upon the hull profile, beam, working draught, length and stability based on the deck load it carries. Indications are however that the pipeline is susceptibility to direct wave action and movement in the shallower water sections. This is independent of the vessel motions, but a function of the catenary profile, stinger design and configuration. Indication as that the limiting sea state will be in the region of Hs 1m to Hs 2m, subject to the wave heading and period. When considering the limiting weather conditions, the accelerations at the stinger need to be understood in terms of the limits for safe personnel working and whilst installation sea states beyond this limit may theoretically be possible but practicality and safe limits may preclude laying in higher weather conditions. The currents speed may require adjustment of the ship heading which may bring waves onto the vessel in a more unfavourable (or better) direction and therefore the maximum extent of ship ‘crabbing’ required should be determined by way of closer examination of the tidal current speeds. This is especially the case in the shallow water areas. Due to the installation being performed as continuous unspooling of the pipeline then pauses for the Zap-Lok™ connection there are plenty opportunities to consider a laydown of the pipeline should the forecast wave conditions be deemed unsafe to continue.



6.0 TEMPORARY STABILITY REQUIREMENTS The temporary stability of the pipeline has been assessed assuming the pipeline is empty. The weather conditions are undefined since the month for laying the pipeline is not yet confirmed, but it is expected to be in the summer season. The pipeline is very light and hence the limiting conditions will be assessed for stability in the following water depths.

Water depth

Maximum H (no current)

Maximum current (Hs 2m)

14m 1.5 – 2.0m <0.1m/s

25m 3 - 3.5m ~0.6m/s

35m 4 - 4.5m n/a

50m 5 – 6m n/a

70m 6 – 7m n/a

90m 7 – 8m n/a

Table 1 - Estimated conditions to destabilise the pipeline (preliminary)

In the absence of any wave action the pipeline appears to be stable in currents up to circa 1.5knots, measured 1m above the seabed. In the shallow water of 14m the pipeline is very sensitive to the wave period and height and thus may be unstable in relatively benign conditions. Concrete mattresses will be installed by the Installation Contractor to aid stability of the pipeline As the pipeline moves into the deeper water sections beyond approximately 25 – 30m in will be less affected by wave action; however, it will be more exposed to swell waves, which can penetrate deeper through the water column.



APPENDIX A – Lay Tables



Normal Lay Analysis

Seabed friction 0.5

Water depth 14 m

Pipe weight subsea 9.44 kg/m (dry) SMYS 448 Mpa

Stinger radius 40 m Stinger length 30 m

Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) Ship move

(m) Top tdp

54 -0.2 -0.36 58.0 18.0 327

59 0.0 -0.18 62.0 18.0 328

61 0.1 -0.04 64.0 18.1 328

65 0.3 0.11 68.0 18.0 329 -1.0

72 0.4 0.28 75.0 18.0 329 -0.8

77 0.6 0.46 80.0 18.3 334 -0.6

83 0.8 0.66 85.0 18.2 334 -0.4

88 1.0 0.89 90.0 18.4 339 -0.2

98 1.3 1.18 100.0 18.7 346 0.0

108 1.7 1.57 110.0 19.0 353 0.2

118 2.2 2.08 120.0 19.4 362 0.4

134 3.0 2.82 135.0 20.1 378 0.6

154 4.0 3.89 155.0 19.3 369 0.8

179 5.6 5.49 180.0 17.2 338 1.0

214 8.2 8.06 215.0 14.7 304

Notes: 1. Layback distance is from stern to touchdown point on seabed

2. Catenary length is from stern to touchdown point on seabed 3. Ship move is the allowable distance forward or aft from a chosen layback distance.



Normal Lay Analysis

Seabed friction 0.5

Water depth 20 m



Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) Ship move

(m) Top tdp

58 -0.2 -0.40 64.0 0.0 408

62 0.0 -0.18 68.0 0.0 328 -2.0

70 0.2 0.03 75.0 0.0 330 -1.5

75 0.4 0.24 80.0 0.0 332 -1.0

86 0.7 0.47 90.0 0.0 332 -0.5

96 1.0 0.77 100.0 0.0 334 0.0

112 1.4 1.20 115.0 0.0 338 0.5

132 2.0 1.84 135.0 0.0 350 1.0

158 3.1 2.93 160.0 0.0 368 1.5

198 5.2 5.02 200.0 0.0 402 2.0

269 9.7 9.48 270.0 0.0 341





Normal Lay Analysis

Seabed friction 0.5

Water depth 30 m



Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) Ship move

(m) Top tdp

64 0.0 -0.28 75.0 0.0 434

70 0.2 -0.09 80.0 0.0 330

81 0.3 0.09 90.0 0.0 331 -3.0

87 0.5 0.30 95.0 0.0 332 -2.0

103 0.8 0.54 110.0 0.0 335 -1.0

119 1.1 0.89 125.0 0.0 337 0.0

140 1.7 1.43 145.0 0.0 340 1.0

171 2.6 2.39 175.0 0.0 349 2.0

222 4.6 4.30 225.0 0.0 378 3.0

313 9.3 9.05 315.0 0.0 419





Normal Lay Analysis

Seabed friction 0.5

Water depth 50 m



Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) Ship move

(m) Top tdp

83 0.4 0.00 105.0 0.0 417

89 0.5 0.08 110.0 0.0 360 -6.8

96 0.6 0.18 115.0 0.0 332 -5.1

108 0.7 0.32 125.0 0.0 334 -3.4

120 0.9 0.49 135.0 0.0 335 -1.7

131 1.1 0.72 145.0 0.0 337 0

153 1.4 1.05 165.0 0.0 340 1.7

180 1.9 1.56 190.0 0.0 345 3.4

216 2.8 2.39 225.0 0.0 351 5.1

268 4.3 3.90 275.0 0.0 374 6.8

325 7.6 7.21 330.0 0.0 401





Normal Lay Analysis

Seabed friction 0.5

Water depth 90 m



Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) Ship move

(m) Top tdp

109 0.8 0.18 155.0 0.0 489

117 0.9 0.24 160.0 0.0 466

130 1.0 0.33 170.0 0.0 435 -12.0

143 1.1 0.43 180.0 0.0 393 -9.0

156 1.2 0.57 190.0 0.0 342 -6.0

169 1.4 0.75 200.0 0.0 340 -3.0

192 1.6 1.00 220.0 0.0 342 0.0

215 2.0 1.35 240.0 0.0 345 3.0

248 2.5 1.85 270.0 0.0 349 6.0

291 3.2 2.60 310.0 0.0 356 9.0

314 4.6 4.00 330.0 0.0 373 12.0





Normal Lay Analysis

Seabed friction 0.5

Water depth 90 m



Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) Ship move

(m) Top tdp

109 0.8 0.16 155.0 0.0 334 -15.0

117 0.9 0.23 160.0 0.0 335 -12.0

130 0.9 0.32 170.0 0.0 336 -9.0

143 1.1 0.43 180.0 0.0 337 -6.0

156 1.2 0.57 190.0 0.0 338 -3.0

169 1.4 0.75 200.0 0.0 340 0.0

192 1.6 1.00 220.0 0.0 342 3.0

215 2.0 1.35 240.0 0.0 345 6.0

248 2.5 1.85 270.0 0.0 349 9.0

291 3.2 2.60 310.0 0.0 356 12.0

314 4.6 4.00 330.0 0.0 373 15.0





HDD Pipeline Recovery

Seabed friction 0.5

Water depth 14 m



Length of A&R wire out (m)

Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) A&R Wire Pipeline

tdp

80.0 88 1.0 0.8 90.0 4.8 92

70.0 88 1.1 1.0 90.0 4.0 78

60.0 93 1.1 1.0 95.0 3.9 75

50.0 93 1.1 1.0 95.0 3.8 73

40.0 93 1.1 1.0 95.0 3.6 70

30.0 93 1.1 1.0 95.0 3.4 66

20.0 98 1.0 1.0 100.0 2.9 57

10.0 98 1.0 0.9 100.0 2.2 45

0.0 98 1.3 1.2 100.0 18.7 346


2. Catenary length is from stern to touchdown point on seabed



Pipeline Laydown at Platform

Seabed friction 0.5

Water depth 88 m



Length of A&R wire out (m)

Layback distance

(m)

Tensions (tonnes)

Catenary length (m)

Max bend moment

(kNm) Max stress

(Mpa) A&R Wire Pipeline

tdp

0 184 1.5 0.9 212.0 17.5 324

20 184 1.5 0.9 212.0 18.2 336

45 184 1.5 0.9 212.0 4.2 81

70 184 1.4 0.9 212.0 4.3 83

95 180 1.3 0.9 207.9 4.6 87

120 178 1.2 0.8 206.0 5.0 95

145 176 1.0 0.7 204.2 5.4 101

170 178 0.9 0.6 206.0 4.7 88

195 179 0.9 0.6 207.5 1.5 30


2. Catenary length is from stern to touchdown point on seabed



APPENDIX B – Dynamic Analysis Results



14m water depth - Pipeline Stress - Quartering Seas H 2m, T 5s



Range Graph: Line13 Max von Mises Stress, t = 20.000 to 25.000s

Minimum Maximum Mean Allowable Stress

Arc Length (m)100806040200L

ine

13

Max v

on

Mis

es S

tress (

kP

a),

t =

20.0

00 t

o 2

5.0

00

s

400E3

350E3

300E3

250E3

200E3

150E3

100E3

50E3

0





ine

13

Max v

on

Mis

es S

tress (

kP

a),

t =

18.0

00 t

o 2

5.0

00

s

400E3

350E3

300E3

250E3

200E3

150E3

100E3

50E3

0









ine

13

Max v

on

Mis

es S

tress (

kP

a),

t =

12

.300

to

17.3

00s

400E3

300E3

200E3

100E3

0





ine

13

Max v

on

Mis

es S

tress (

kP

a),

t =

18

.000

to

25.0

00s

400E3

300E3

200E3

100E3

0




90m water depth - Pipeline Tension at Top of Stinger - Quartering Seas H 4m, T 7s

OrcaFlex 9.8e: S-NL-4-90m.sim (modified 16:05 on 31/05/2016 by OrcaFlex 9.8e)

Range Graph: Line7 Max von Mises Stress, over Whole Simulation



ine

7 M

ax v

on

Mis

es S

tress (

kP

a),

t =

-5.0

00 t

o 2

5.0

00

s

400E3

300E3

200E3

100E3

0

OrcaFlex 9.8e: S-NL-4-90m - H4m T7s.dat (modified 11:02 on 01/06/2016 by OrcaFlex 9.8e)

Time History: Line7 Effective Tension at End A

Time (s)2520151050-5

Lin

e7 E

ffe

ctive T

en

sio

n (

kN

) at

End

A

35

30

25

20

15

10

5

0

Documents

PIPELINE INSTALLATION ANALYSIS REPORT