Buoyancy Supported Riser (BSR/شناور پشتیبانی رایزر

این فیلم عملکرد شناور پشتیبانی رایزر (BSR)  در سازه FPSO را نشان می دهد.

Buoyancy Supported Riser (BSR)

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ایده و سرمایه گذاری این سازه دریایی توسط شرکت پتروباس در کشور برزیل ساخت شد. اسم این سازه بر حسب عملکرد آن بنام شناور پشتیبانی رایز ( BSR) می باشد. که این سازه در یک سطح آب زیر دریا FPSO به حالت شناور غوطه ور قرار می گیرد.هزینه پروژه 1 میلیاد دلار  تمام شد. قرارداد پروژه EPCI می باشد که در متن انگلیسی به آن اشاره شده است.

BSR نستباﹰ سطح، ساختار شناور مستطیل شکل با وزن ما بین 2000 تا 2250 تن می باشد نصب این سازه در عمق 250 متر (820 فوت ) می باشد. سیستم BSR  طور طراحی شده برای جذب نیروی دینامیکی FPSO و جلوگیری از خستگی رایزر های تحت کشش و در نتیجه تنش ها دینامیکی را به حداقل برساند.

Buoyancy Supported Riser (BSR)

Balltec has developed and commissioned a pioneering subsea chain tensioning system and tether top connector for the first Buoy Supported Riser (BSR) System installed on the Guará-Lula Project. Balltec took on their largest project to date for the design, manufacture, assembly and testing of 36 tether top connectors and six subsea chain tensioners for the BSR system

The Guará-Lula project is the largest engineering, procurement, installation and commissioning (EPIC) Subsea, Umbilical, Riser and Flowline (SURF) contract ever to be awarded in Brazil. The project, operated by Petrobras, is located in the Guará and Lula pre-salt fields in Santos Basin. The BSR system features four large subsea buoys which, when moored and tensioned, will support 27 steel catenary risers. Each buoy weighs approximately 2,000 tonnes and is installed 250 metres below sea level

Operator Petrobras conceived the idea behind the Buoyancy Supported Riser (BSR) system, which involves deployment of submerged buoys at a midwater level below the FPSO. Following a design competition, Subsea 7 was appointed to take the concept forward as part of a $1-billion SURF contract for Guara-Lula NE

Balltec was invited by Subsea 7 to participate in a design competition against more established oil and gas engineering companies. Balltec utilised its mooring expertise and extensive engineering abilities to develop a workable conceptual design for the connectors and tensioning system to moor and tension the subsea buoys into their final position. The top tether connectors were designed to accommodate 162 mm chain. Balltec’s proposal was selected as the ideal solution and secured the contract for the company. The chain tensioning system and tether top connector were successfully taken from concept design through to delivery within 18 months of the contract being awarded, which is considered an aggressive lead time for the size and demands of the project. During the design and engineering process a significant amount of time was invested into research and development of the connectors and tensioning system. As the concept was a world’s first, detailed FEA and fatigue analysis were carried out to ensure the connectors and tensioners were technically viable and could adhere to project specific requirements. Additional research was carried out in chain tribology, out of plain bending and corrosion analysis, which included full scale prototype testing of both the connector and the tensioner. Det Norske Veritas (DNV) reviewed and certified the connector and tensioner throughout various stages of the project from design approval to construction and testing

The tether top connectors consist of two parts; the chain management structure and the central structural core. The central structural core is the main load bearing assembly in the tether top connector. It is designed to articulate to a maximum angle of +/- 15 degrees in a 360 degree orientation to allow buoy movement during service and to accommodate a survival load case. The chain is locked into position by a series of chain dogs, at the bottom of the central structural core, offering a one link tension resolution

The central structural core is designed to accommodate a maximum chain tension of 9,380 kN (956 mT). The chain management structure is a stationary assembly that interfaces with the submerged buoy, provides lifting points to deploy the tether top connectors subsea and manages any excess chain, ensuring that no collision occurs during the maximum articulation of the central structural core. The tether top connector was designed for a 27 year service life and a 270 year fatigue life. The connector was also provided with its own cathodic protection system that was calculated and designed by Balltec

The tensioning system developed by Balltec is a temporary subsea installation device that can be docked onto the tether top connectors and tensions or slackens the tethers at an operating depth of up to 300 metres. The tensioner was also designed to a maximum tension capacity of 9,380 kN (956 mT) with a 1,750 mm stroke. The tensioner is controlled via dedicated PLC software and a control system developed by Balltec enabling the tensioner to be operated either from the surface or subsea using an ROV skid to provide the power and communications line.

Since starting the Guará Lula project, Balltec has grown as a business to accommodate the larger contract whilst maintaining the delivery of core products. In 2011 Balltec moved to larger premises totalling 75,000ft2 (6,968m2) and expanded their workforce across all departments. A 24/7 working pattern for the production and testing of the connectors and tensioners was introduced during the project execution. The additional space enabled Balltec to design and build the required rigs (for assembly, R&D, proof load and function tests) that enabled the successful delivery of the contract within 18 months

The first buoy and set of connectors has been successfully installed, moored and tensioned, all of which was overseen by Balltec’s experienced technicians and engineers. The second buoy is currently being installed and tensioned

The project scope includes engineering, procurement, installation and pre-commissioning of four de-coupled BSR systems, to be installed early next year in a water depth of more than 2,100 m (6,890 ft).The BSR system is designed to absorb the dynamics from the FPSO, resulting in minimized dynamic stresses on the SCRs, and making them behave instead like a long, free-spanning pipeline, with the main fatigue response arising from vortex-induced vibration generated by localized currents. As the SCRs’ dynamic response is so low, BuBi mechanically lined pipe can be used for the SCR section, technology applied since 1995 on towed pipeline bundle projects. However, this will be the first BuBi application involving installation via the reel-lay method, considered more cost-effective for the Petrobras project, and made possible following a recent joint development program by Subsea 7 and stainless steel manufacturer BUTTING. Although it missed out on the ASME prize, the ACM has been qualified by Petrobras following guidelines recommended by DNV RP-A203 Qualification of New Technology

Early next year the Seven Oceans vessel will perform the reel lay and hookup to the subsea buoys. Guara-Lula NE’s associated production and injection lines will also be manufactured from BuBi mechanically lined pipe

قرارداد های که در کارهای نفتی و پتروشیمی کاربرد زیادی دارد.

فهرست بهاء خاص  what is Unit Rat contract/Unit Rat

در برخی از کارهای به دلیل خاص بودن و داشتن صعوبتهای خاص و یا در صورت عدم وجود فهرست بهای معاونت برنامه ریزی، مانند پروژه های نفتی و پتروشیمی، مشاور نسبت به تهیه بهای خاص جهت همان پروژه اقدام می نماید.  

قراردارد EPCI چیست؟ / What is EPCI Contract

مهندسی، تدارک، اجرا و نصب ( Engineering Procurement Construction Install) از این نوع قرارداد  برای ساخته پایانه /ترمینال شناور بارگیری و تخلیه در خلیج فارس استفاده شده است.