Environmental Effect on Fatigue Life of FPSO Hull Structures

Author(s):  
Xiaozhi Wang ◽  
Booki Kim ◽  
Yanming Zhang ◽  
Ping Liao

Floating production, storage and offloading systems (FPSOs) have been widely used in the development of offshore oil and gas fields because of their many attractive features. These features include a large work area and storage capacity, mobility (if desired), relatively low construction cost and good stability. They are mostly ship shaped, either converted from existing tankers or purpose built. The hull structural scantling design for tankers may be applicable to FPSOs; however, FPSOs have their own unique characteristics. FPSOs are located at specific locations with a dynamic loading that is quite different from that arising from unrestricted ocean service conditions for tankers. It is also noted that the wave conditions in recent FPSO applications may be very complicated when operating in areas such as those offshore West Africa and offshore Brazil where both seas and swells exist and propagate in different directions. In this paper, the unique FPSO operational aspects, especially the load assessment due to on-site environments will be described. The methodology of handling complicated wave conditions in fatigue assessment will be addressed. Special considerations for converted FPSOs, which need to take into account their operational history as a trading tanker and low cycle fatigue due to FPSO operations, will also be introduced. Case studies will be presented and appropriate analysis methodology will be summarized. The methodology has also been adopted by ABS Guide, see ABS [1].

2021 ◽  
Vol 775 ◽  
pp. 145485
Author(s):  
Yiqian Liu ◽  
Hao Lu ◽  
Yudong Li ◽  
Hong Xu ◽  
Zhicheng Pan ◽  
...  

1987 ◽  
Vol 27 (1) ◽  
pp. 357
Author(s):  
M. Thatcher ◽  
D.B. Marietta

Subsea production systems have been an accepted method of developing offshore oil and gas fields since the installation of the first subsea trees in the early 1960s offshore California. Generally subsea completions have been done from floating drilling vessels on wells with subsea wellhead equipment. A number of wells have been completed subsea by bottom supported jackup rigs on wells drilled using mudline suspension equipment. The subsea completion equipment and methods utilised to adapt mudline suspension wells for a subsea production tree are described. This method of completion offers important benefits as it allows completion of wildcat or delineation wells, it can be used in areas of small, scattered reservoirs, and it can be used in conjunction with floating production systems. The cost associated with these subsea completions is roughly equivalent to those of standard subsea completions from floating vessels. An overview of a typical completion system is presented and compared.


1999 ◽  
Vol 121 (2) ◽  
pp. 71-76 ◽  
Author(s):  
K. P. Thiagarajan ◽  
S. Finch

Turret-moored floating production storage and offloading (FPSO) vessels have found application in several offshore oil and gas fields in Australia’s North West Shelf (NWS). These vessels are either custom-built or converted tankers, with an internal or external turret. The position of an internal turret is decided based on a number of design considerations, primarily, available deck and interior space, and weathervaning capabilities. It is known that turret position can influence vertical motions and accelerations of a vessel, but this factor has not been given much importance, in comparison with the effects on the horizontal plane motions, primarily surge. This paper presents the results of a pilot study conducted at the Australian Maritime College, Tasmania, to study the vertical motions of a single-point moored FPSO model in waves, while systematically varying the mooring position across the length of the model. The displacement of the vessel was held constant at 50-percent-loaded condition. A single-point mooring system was designed and implemented on the model to simulate the prototype turret mooring system. Results show that the mooring location significantly affects the vertical motions and accelerations of the vessel. Astern turrets were found to produce higher heave and pitch than other locations tested. Although turrets positioned close to the longitudinal center of gravity produced the lowest overall motions, it is suggested that turret position forward of midships be preferred, as it provides a balance between lowering vertical motions and improving weathervaning characteristics.


Author(s):  
Chingiz Saibovich Guseinov ◽  
Dmitry Leonidovich Kulpin ◽  
Galie Hamzaevna Efimova

The article dwells upon the problem of developing offshore oil and gas fields around the world accompanied by producing not only stationary and semi-submersible rigs and drilling vessels, but also a large number of auxiliary vessels for various functional purposes. It would be impossible to extract offshore hydrocarbons under the sea bed without them. Special fleet was formed during the years of development of offshore oil and gas fields in the Russian Federation, the part of it being imported. In the upcoming years, our country will face some challenges related to the development of Arctic reservoirs which are mainly located in the long-frozen deep seas. Their development in deep water will only be possible with auxiliary fleet, as it will be necessary to build deep water drilling vessels and other facilities/vessels. The types of vessels of the modern oil and gas fleet are presented, depending on the area of navigation, the depth of use and the specifics of the work performed. It is noted that currently in world practice there are no examples of using proven drilling and production technologies in severe ice conditions, when ice thickness exceeds 2-3 m, because the modern ice-resistant stationary platforms can not withstand the load at a depth of more than 80-100 m. The auxiliary fleet will both service offshore rigs and ensure their long-term productivity and functionality. For the development of oil and gas fields in the long-frozen Arctic deep-sea areas it is necessary to create a full-fledged underwater oil and gas fleet.


Author(s):  
Николай Панасенко ◽  
Nikolay Panasenko ◽  
Алексей Синельщиков ◽  
Aleksey Sinel'schikov ◽  
Павел Яковлев ◽  
...  

The article touches upon the problem of technogenic risks arising in the course of building and operating oil and gas complexes in the Caspian Sea taking into account the adoption of the Con-vention on the legal status of the Caspian Sea and regulation of the territorial division of the Caspian Sea. Technological risks are presented from the position of safety of industrial facilities in the offshore area and in the coastal zone, the impact of these facilities on the ecology of the Caspian is considered. The risk analysis was carried out taking into account world experience, as well as incidents that occurred at the offshore oil and gas production facilities in the Caspian Sea. There has been presented the layout of oil and gas fields at the bottom of the Caspian Sea and the division of the bottom based on adopting the Convention. A general description of the Caspian Sea has been given; unique features of the Caspian and the most unexplored seismic effects have been stated. It has been recommended to conduct a comprehensive assessment of the state of the seabed according to seismological, mud, volcanic and engineering-geological conditions; to develop measures for preventing and reducing the damage from hazardous natural processes and exploitation of oil and gas fields; to forecast the fluctuations of the Caspian Sea level, taking into account today’s economic activity; to study the natural and technogenic factors determining the environmental safety of the Caspian Sea; to monitor seismic phenomena, crustal movement in zones of tectonic faults at the sea bottom, etc. The speed and direction of wind currents in the Caspian Sea have been analyzed. The maps of mud volcanoes location in the Caspian basin (located on land, hidden and identified by seismic, geological, geophysical and geochemical methods, etc.) are illustrated. Conclusions are made about the high risks for developing hydrocarbon deposits in the Caspian Sea basin. There is the need to take into account environmental requirements and standards, to use modern technologies, to prevent incidents at offshore oil and gas production facilities.


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