203 Introduction This project is included in the development of the second phase of the offshore field of Rosa, located at 200 km from the Angolan coast, in the block 17 * operated by Total E&P Angola. To produce oil and gas, Total had to install a subsea production system in this depth of water, connect hundreds of pieces of equipment and set up flow lines and risers to bring effluent up to the FPSO. The Girassol FPSO (Floating Production Storage Offloading) is a production and storage ship that has the advantage of being fully autonomous. The wellheads are installed on the seabed and connected to the surface facilities by rigid flow lines on the seabed and riser systems that bring the effluent up to the surface. These systems are designed to handle extreme ocean states and weather conditions. The FPSO comprises a seawater disulphating unit, an oil treatment and stabilisation plant as well as pumps, generators and of course oil storage tanks. The combined plant can process up to 200,000 barrels per day of crude oil, can disulphate and re-inject 400,000 b/d of seawater and store 2 million barrels of processed crude. The oil is then piped to the offloading buoy moored 2 km from the FPSO. Module 5 For the Rosa development, Total ordered to Suez-Ondeo the supply of a desalinisation skid to produce treated seawater (module 5). Ondeo takes in charge the general design of this skid with HP pumps, osmosis tubes, tanks, valves, instrumentation, etc. This skid had to be ‘key on door’. Also some Belgian companies were active in this project: CTI (Seilles) for the manufacturing of the steel structure and piping, Ensival (Verviers) for the pumps, ATI (Thimister) for electricity and instrumentation and EIV for the design and calculation of the steel structure. Data of the equipment: • Length: 14 m • Width: 8 m • Height (with lifting frame): 6 m • Total weight: 138 To (lifting configuration) • Weight of steel structure: 64 To The module is composed of different parts: • Structure of the main frame; • Structure to support monorails for maintenance of pumps (3 HP pumps with weight of 10 To each); • Structure to support osmosis tubes, with walkways; • Structure to support biocide tanks (at 4.5 m height) with walkways; • Lifting frame for a one hook lifting (this one will be cut off after installation). The specificities of this project, like these of all the other modules on the FPSO, are that they have to be calculated for different configurations: • In Place: equipment in place on the FPSO, with operating conditions and taking into account roll and pitch, wind; • Transportation: equipment on the barge for the travel to the FPSO (from Rotterdam to Girassol), taking into account more severe conditions of roll and pitch, in relation with the size of the barge; • Lifting with one crane: equipment to be lifted on the FPSO with one floating crane, taking into account the centre of gravity, the calculation and the design of the shackles and the pad eyes; • Installation: this part includes the calculation of the bumpers and shocks with the installation guides; • Lifting with two cranes: equipment to be lifted on the manufacturing workshop yard; • Load-out: equipment to be transported with a trailer between the workshop and the yard. As these configurations required a lot of information, the calculation files were very big to work with. For this reason, we used different files for these different configurations. For this description, we only join the calculation file for the lifting configuration. For the other files, the calculation model is quite the same, except lifting frame and bumpers. For the calculation, some other difficulties came from the habits of the petroleum sector: they are working with US standards, as API-AISC, and they use usually a specific calculation software (they didn’t know anything about SCIA). For the first problem, although a specific module of SCIA•ESA PT exists for US-code, we discussed with the customer to use Euro code with some adaptations. For the second problem, they mentioned the advantage of SCIA with its graphic interface, more friendly and easy to use. The calculation required a long preparation to envisage all the combinations for the different configurations. For example, for the in-place configuration, we have to combine: • Dead weight of the structure; • Weight of the equipments (pumps, piping, tanks,...); • Contents of the equipments; • Overload for the walkways; • Wind in the different directions; • Roll and pitch due to the sea. For the calculation report, due to particular requirements of our customer, we used the classical word format file, including tables and graphics from SCIA•ESA PT. This method didn’t cause any problem. In conclusion, this type of project was a little bit new for our company, especially with all the specifications in relation with the fact that this equipment had to operate on a floating structure, but we learned many things about the working methods of this sector. SCIA•ESA PT helped us to meet the multiple requirements of our customer. * Sociedade Nacional de Combustiveis de Angola (Sonangol) is the Block 17 Concessionaire. Total E&P Angola is the Operator in the Block. Total’s coventurers are Esso Exploration Angola (Block 17) Ltd., BP Exploration (Angola) Ltd., Statoil Angola Block 17 AS and Norsk Hydro Dezassete AS. Total Rosa – Girassol – Module 5
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