Arctic Environment
Arctic Overview
Generally, it is common to define the arctic area as all the northern regions which experience arctic conditions and where the environment has arctic properties in Offshore Engineering. These regions can be seen on the map below: Baffin Bay, Barents Sea, Beaufort Sea, Chukchi Sea, Kara Sea, Laptev Sea. During the recent years deep water hydrocarbon fields have been found offshore. As can be deducted from the definition of the arctic region, the hydrocarbons in this area are very difficult to access. The remote reserves are mostly located beneath deep waters which are frozen over with thick ice layers during most of the year. Together with the harsh weather conditions and extreme cold this makes offshore exploration in the arctic one of the last frontiers in the industry. A frontier that now increasingly has got worth tackling. Estimates say that 30% of the global hydrocarbon reserves are located within the Arctic Circle. The disconnectable mooring system can be used in the arctic environment because the FPSO can sail to safe area through the disconnection. |
Ice Extent
Satellites have continually monitored polar sea ice since 1979, and since the turn of the twenty-first century, Arctic sea ice has declined relative to its 1979–2000 mean extent. According to the National Snow and Ice Data Center (NSIDC), sea ice extent at the most recent summer minimum (September 2009) and winter maximum (March 2010) was greater than it had been in the most recent years, but this short-term gain did not yet indicate a reversal of the long-term decline.
This pair of images shows the latest updates to the the Earth Observatory’s World of Change: Arctic Sea Ice feature. They show Arctic sea ice extent for the September 2009 minimum (left) and March 2010 maximum (right). In both images, gray indicates land, dark blue indicates ice-free ocean water, and white indicates ice concentrations. Yellow lines in each image indicate the median for that month based on observations from 1979 to 2000. The images are based on data from the Advanced Microwave Scanning Radiometer for EOS(AMSR-E), a Japanese-built sensor that flies on NASA’s Aqua satellite. More information can be found at NSIDC.
Satellites have continually monitored polar sea ice since 1979, and since the turn of the twenty-first century, Arctic sea ice has declined relative to its 1979–2000 mean extent. According to the National Snow and Ice Data Center (NSIDC), sea ice extent at the most recent summer minimum (September 2009) and winter maximum (March 2010) was greater than it had been in the most recent years, but this short-term gain did not yet indicate a reversal of the long-term decline.
This pair of images shows the latest updates to the the Earth Observatory’s World of Change: Arctic Sea Ice feature. They show Arctic sea ice extent for the September 2009 minimum (left) and March 2010 maximum (right). In both images, gray indicates land, dark blue indicates ice-free ocean water, and white indicates ice concentrations. Yellow lines in each image indicate the median for that month based on observations from 1979 to 2000. The images are based on data from the Advanced Microwave Scanning Radiometer for EOS(AMSR-E), a Japanese-built sensor that flies on NASA’s Aqua satellite. More information can be found at NSIDC.
Ice-Structure Interaction
When the ice is acting on the structures, the ice will be failure in different modes, which include creep, radial cracks, buckling, circumferential cracks, spalling and bending. For the ice-FPSO interaction, we consider the ice failure mode is bending. The bending failure can be divided into 3 steps, which are showed left. |
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According to the model based on elastic beam bending, the horizontal action component is determined as given by the following equation, Fh = (HB + HP + HR + HL + HT)/(1 - HB / (σf * lc * h)) where HB is the breaking load; HP is the load component required to push the sheet ice through the ice rubble; HR is the load to push the ice blocks up the slope through the ice rubble; HL is the load required to lift the ice rubble on top of the advancing ice sheet prior to breaking it; HT is the load to turn the ice block at the top of the slope. The detailed calculation will be elaborated in the case study. |