Análisis de la hipótesis general

Detailed offshore installation methods will be developed during engineering phase.

This section preliminary outlines CONTRACTOR’s installation plan:

 Survey support Vessels, sub-contracted; (if required)

 Dredging Spread, sub-contracted;

 Derrick Laybarge Castoro 2, owned by CONTRACTOR;

Derrick Laybarge Castoro 8, owned by CONTRACTOR;

 Diving Support Vessels, sub-contracted;

 Suitable Support Vessels to be rigged with Carousel for Cable Laying, sub-contracted.

Moored installation vessels (DLB Castoro 2, DLB Castoro 8) will be supported by two (2)

suitable AHTs for anchor handling operations and by three (3) suitable AHTs during moorings

and unmoorings.

be DP Class 2 with mooring / spud capabilities for works in shallow waters.

Offshore fields ARABIYAH and HASBAH are in close vicinity to the international border with

Iran, therefore attention will be given to the vessel mooring as well as movements within field.

4.7.4.1 Survey Works

CONTRACOTR will perform Surveys during Contract execution and in particular:

Pre-engineering Survey

Pre-engineering survey will comprise the acquisition of geophysical and geotechnical data along

the survey corridors for pipelines and cables detailed engineering.

Survey will be performed to determine the bathymetry, seabed morphology and sub-seabed

geology along the pipelines/cables route, along anchor corridor and at proposed new platforms

locations.

It will mainly consist in:

‐ Geophysical and geotechnical seabed survey of ARBI and HSBH flowline routes and

geophysical seabed survey of area around the ARBI and HSBH tie-in and wellhead

platforms;

‐ Geophysical and geotechnical seabed survey of first 40 km of the ARBI and HSBH

trunkline routes ;

‐

Geophysical and geotechnical seabed survey of the remaining sections of pipeline route

corridors (from HSBH KP 40.000 to II-P and from ARBI KP 40.000 to shoreline) including

geophysical seabed survey of the 3000 m x 3000 m area centered at II-P;

‐ Geophysical and geotechnical seabed survey of single cable routes (cable route from

Abu Ali shore to II-P and cable route from MRJN GOSP-2 to HSBH TP-1).

‐

If deemed necessary by CONTRACTOR:

o Nearshore Geophysical survey and Geotechnical 15 x 5m deep boreholes along

36” trunklines at Kursaniyah and between 119.8 KP and KP120.5

o Nearshore Geophysical survey and Geotechnical 2 x 2m deep boreholes along

15kV composite power cable shore approach at Abu Ali

o Geotechnical survey deep borehole at ARBI & HSBH Tie-in platform and flare

locations

As-laid survey

As-laid survey of pipelines will be performed prior to flooding and tie-in primary to detect free-

spans or anomalies.

.

4.7.4.2

Dredging, Trenching and Backfilling of Pipelines and Cable

ARABIYAH-HASBAH shore approach section is defined as the 3.1 km long section between

designated LTE point and 5,2m WD LAT. This section will be pre - dredged prior to pipeline pull

and installation in accordance to tender requirements. Minimum pipeline trench depth will be

sufficient to achieve 1m top of pipe burial coverage.

Dredging till approx 0.5m WD of shore approach will be done using suitable land base

excavator with elevating capabilities. Excavated material will be stored along the trench.

Further trench excavation towards deeper waters is envisaged by means of suitable back hoe

dredger.

Dredging/trenching equipment will be carefully chosen in a way to ensure enough overlap

between BHD and land base excavator working range.

A near shore laybarge navigational / access channel 90m wide, 400m long and 4.5m LAT

approximately 8.28km from onshore line will be dredged. All dredged material from this access

channel will be transported and deposited in the approved soil dumping area indicated by

COMPANY.

Backfill operations will start after confirmation that pipelines have been installed into the trench

i.e. once pipelines are shore pulled and laid pipelines surveyed (as-laid survey). The laybarge

navigational / access channel will not be backfilled. Backfilling works will be carried out using

the same equipment in their ranges (BHD and land based excavator).

4.7.4.3 Pipelines Installation

CONTRACTOR will mobilised the following main spreads for Pipelines Installation works:

 Castoro 8: 36” trunklines from 17m WD to Tie- In Platforms (ARBI and HASBAH)

 Castoro 2: Shore pull and all other pipelines

DLB Castoro 2 will perform pipe-lay of single pipejoint (typ.12.2m), while DLB Castoro 8 will

perform pipe-lay of double pipejoints (typ. 24.4m).

4.7.4.4 Structures Installation

CONTRACTOR will mobilised the following main spreads for Structure Installation works:

 Castoro 8: HSBH TP1 and ARBI TP1 and TP2 Platforms – or any other Heavy Lift

Vessels if needed.

 Castoro 2: All WH Platforms.

4.7.4.5 Subsea Installation Works

Diving works will be performed from dedicated Dive Support Vessels. Vessels will be equipped

with saturation system, work class ROV, suitable crane. Vessels will be DP2.

Subsea installation works will comprise the following activities:

 Preparatory works at Wellhead Jackets for Risers installation and Riser final positioning;

 Installation of tie-in and wet stored spools (wet storage by Castoro 2 and Castoro 8);

 Installation of protection shrouds on spool flanges;

 Assistance to Pre-commissioning activities;

 Installation of J-tube at Marjan GOSP 2 Platform;

 Grout bags installation, supports for spools, cables;

 Crossing preparation;

 Installation of 4” flexible pipelines between Platform ARBI TP2 and 36” ARBI Trunk-line

and 36” HSBH Trunk-line and connection to Trunk-lines;

 Installation of Impressed Current Cathodic Protection (ICCP) at WHP and Tie-In

Platforms;

 Free-span corrections, if and where required.

4.7.4.6 Cable Installation Works

CONTRACTOR will mobilize equipment (Carrousel) to be rig onto a suitable Vessel to lay

Cables.

The breakdown of the installation SoW will be provide in the Installation Manuals.

4.7.4.7 Hydrotesting and Pre-commissioning

CONTRACTOR will carry out this activity. The battery limits will be identified as per COMPANY

Specifications and approved Project procedures. Assumed is utilization of two vessels

(suppliers) for offshore works. Pre-commissioning will be supported by divers.

4.7.4.8

Onshore facilities to support offshore operation

Offshore logistic and support to the offshore operations will be performed from Tanajib Port.

CONTRACTOR will deploy a logistic team based at CONTRACTOR light storage area Yard 10.

Tanajib Port will be used for crew changes, loading supply vessels and logistic.

CONTRACTOR will select at a later stage, based on selected coating yard subcontractors, the

most appropriate port to load pipes onto cargo barges.

4.8 ONSHORE CONSTRUCTION AND INSTALLATION

In document FACULTAD DE INGENIERÍA (página 125-134)