Offshore Facility Fabrication/Construction and Installation In-country/Out-country Fabrication The offshore described in the preceding sections will either
be fabricated within Malaysia or out-country where the fabrication is possible and the different segments source internationally to the location for assembling stage. In-country will utilized the existing national fabrication yards. The principal in-country fabrication yards under consideration will be Labuan fabrication yard located to the south of the Sarawak due to its proximity to the site. Petra Energy fabrication yard located in shah lam will be used for the fabrication of process equipment. At the time of drafting this report the construction contract wasnt awarded to EXXOM as such decision on selection of yard or yards has not been finalized. Topside however will be fabricated outside of the federal territory of Malaysia and will be transported using road, rail and the well-established route of Malacca strait to the assemble location. The well-established route will be Singapore railway line and the Malacca strait depending on the origin of each segments. Drilling Template The drilling template will be constructed using a high grade marine steel and will be catholically protected using the zinc aluminum sacrificial anodes. It will be coated with an anticorrosion/anti-fouling paint to prevent corrosion of the transported equipment due to constant incurred contact with the marine environment. The work sequence will be such that individual components are manufactured first and then followed by the welding of the sub components to create a drilling template. To ensure the integrity of the assemble component a Non Destructive Test (NDT) will be performed on the welded joints. The two NDT will namely be Radiographic and Ultrasonic tests. Typical work sequence will follow the pattern below. Fabrication of individual components. Assembling of each component into one structure. NDT before loading on to the transporting vessels.
Jacket (and Piles) The jacket fabrication will required that the inner part being the lattice of the second jacket before the first jacket is completed. The fabrication will follow the conventional fabrication code suggested by the PTS. The jacket will be made of tabular made steel. The fabrication yard is Labuan located in the Sarawak due to its proximity to the site.it has been noted that if the large diameter/heavy wall steel tabular for the jacket and piles exceed the in country capability then the remaining part will be source from international market. Steel plates and the tubes received at the fabrication will be cut and shaped as required and then welded together to form various sectional pieces of the jackets. Once welding has completed, each section will be subjected to NDT to check the section integrity and weld joints, and will be grit blasted in preparation for painting. Once these tests have been completed, each section will be painted with anti-corrosive paint. Cathodic will be provided by using the zinc-aluminum sacrificial anodes. The section will then been transferred to the skid way where they will crane lifted into the position and welded to other jacket sections to form the required section. NDT will be performed once more on the overall welded structure as required. The seabed will be transported to the yard in pre-fabricated section for assembly, grit blating, inspection, testing and painting.
Figure (1): Overview of Jacket Fabrication (Azer et al, 1997) Topside Pre-fabricated components required for the erection of topside will be fabricated in Sapura Kencana yards in section for assembly to ensure the quality of the material supplies from
local suppliers meets specifications. These components for the topside comprises the helideck, main deck, wellhead access platform, cellar deck, sub-cellar deck and SDV access deck. It should be noted that in case some components for topside are to be imported from international markets the prefabricated section should be tested before delivery to the assemble location and once again re-tested for conformity upon delivery to the site. For the topside deck, steel plate will be supplied to the fabrication yard followed by the subsequent cutting, shaping and welding of the steel plates to form a girder box, plate girders and tabular girders. The section will be grit blasted at the workshop before being coated with anticorrosion paint in a ventilated paint facility. Prefabricated utilities and processing equipment will be installed and fitted in designated place within the steel structure. Outfitting of the processing equipment will be done using the power and piping connection as required by the PTS design standard and specifications. All deck frame and welded component will be tested using the NDT method. Integrity and Hydro testing Approximately 96% of the process equipment and utilities on each platform topside will be precommisioned onshore following the installation of the utilities and process equipment onto the deck. Pre-commisioning will take into the consideration the pressure test, with water or gas, hydro testing will be perform using potable water or sea water dosed with sterilizing agent. Where ever sea water is used it will be dosed with sodium hydrochloride at a concentration of 2mg/l. on the completion of the pressure test the water will be removed and reused where possible. Discharge of the sea water will be either to the municipal drains or through the discharge to the harbor. Prior to the discharge any dosed seawater will de-chlorinated using sodium thisulphate, a chemical with very low toxicity which poses no significance environmental risk. Testing will be carried out as follow: Cooling water system Living quarters
Below is the overview of the Topside fabrication process.
Figure (2) Overview of the Topside fabrication process
Load-out and Transportation The completed and pre commissioned offshore facility will be loaded into barges for the transportation to the designated installation site located at Central Luconia of Borneo Northwest Coast, Malaysia. Two barges will be used for the transportation of the offshore facilities The offshore jacket and topside will be sea fastened by welding and bolting the load-out frame to the barge and the barge will be ballasted and trimmed to sea tow condition in readiness for transfer to the offshore location. The jacket pile will be transported by floating method.
Figure (3) Load out method (Azer et al, 1997).
Transportation The transportation will utilize the route that covers the North West coastline of the Sarawak. The transportation vessel are estimated to cover the distance that scratches approximately 200km from Bintulu to the Site in eight hours. Offshore installation The below instruction provides the details regarding the installation of the offshore platform facilities. Drilling Template and Pin Piles Upon reaching the designated location the drilling template will be lifted into the position by the DBA and lowered into the seabed. Once at the seabed the leveling will be accompanied using the hydraulic system. Piles will be used to anchor the drilling template into the place, and is accomplished using hydraulic hammer operated form the DBA. Jackets Once at the site the barge will be anchored in place and the jacket load-out frame sea fastening will be removed. The barge will be blasted to provide a submerged situation to help jacket slid off into the water.
Figure (4): Sequential installation steps for the Jacket.
Jacket tow out The jacket will be lifted using the flotation tank to provide the necessary buoyancy required to pin point the positioning of the jacket into the required position. At the seabed the jacket leg will be docked into pin piles with the assistance of the DBA crane and progressive flooding provide by the buoyancy tanks. Topside The topside is designed for the float over method of installation. Barge will be used to maneuver between the two jacket support towers such that the topside is position at the top as shown in the figure below.
Figure (5): Float over installation method.
Emissions, Discharge and Waste Emissions and discharge and waste that will be generated from the offshore facility fabrication and installation will be taken care of based on the regulation provided in the PTS manual. Typical waste during the offshore fabrication and installation may include paint tins, oily rags, and grit from sand blasting, cardboard wood and packaging materials, hydro test water,
nitrogen gas and sewage. Wastes will be segregated in skips and be brought back to shore for appropriate disposal.
Health, Safety and Environment Guidance aligned to the Regulations - cited within the PTS - to support those who may be affected in understanding their requirements. Accordingly provides a simple explanation of the main regulatory provisions and is addressed to those with duties, such as licensees, installation operators, installation owners, well operators and others involved with offshore activities. The principal regulatory aim is to reduce the risks from major accident hazards to the health and safety of the workforce at such installations - or in connected operations, in response to the central recommendations of the Cullen Report into the 1988 Piper Alpha North Sea oil production platform disaster which killed 167.
