Risk assessment of sea ice disasters on fixed jacket platforms in the Liaodong Bay

Abstract. Sea ice disasters seriously threaten the safety of oil platforms in the Bohai Sea. Therefore, it is necessary to carry out the risk assessment of sea ice disasters on oil platforms in the Bohai Sea. In the study, the risk assessment of sea ice disasters on fixed jacket platforms in the Liaodong Bay was performed. Firstly, the formation mechanisms of sea ice disasters were analyzed and the sources and modes of sea ice risks were clarified. Secondly, according to the calculation formulas of extreme ice force, dynamic ice force and accumulated force, several ice indices such as thickness, motion, strength, period, and concentration were proposed as the hazard indices and corresponding values were assigned to the proposed indices based on ice conditions in the Bohai Sea. Thirdly, based on four structural failure modes (structures overturned by the extreme ice force (Mode 1), structural fracture failure caused by dynamic ice force (Mode 2), facility damage caused by the dynamic ice force (Mode 3), and structural function failure caused by accumulated ice (Mode 4)), the structural vulnerability index, overturning index, dynamic index, ice-induced vibration index, and function index were proposed and corresponding values were assigned to the structural vulnerability index of fixed jacket platforms in the Liaodong Bay. Fourthly, the weight of each risk index was determined according to previous sea ice disasters and accidents and the sea ice risk was calculated with the weighted synthetic index method. Finally, with the above index system and risk assessment methods, the risk assessment of sea ice disasters on 10 jacket platforms in three sea areas in the Liaodong Bay was carried out. The analysis results showed that efficient sea ice prevention strategies could largely mitigate the sea ice-induced vibration-related risks of jacket platforms in the Liaodong Bay. If steady-state vibration occurred (usually in front of the vertical legged structure) or the structural fundamental frequency was high, the structural vulnerability was significantly increased and the calculated risk levels were high. The sea ice risk assessment method can be applied in the design, operation, and management of other engineering structures in sea ice areas.

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Risk assessment of sea ice disasters on fixed jacket platforms in Liaodong Bay

Natural Hazards and Earth System Science ◽

10.5194/nhess-20-1107-2020 ◽

2020 ◽

Vol 20 (4) ◽

pp. 1107-1121

Author(s):

Ning Xu ◽

Shuai Yuan ◽

Xueqin Liu ◽

Yuxian Ma ◽

Wenqi Shi ◽

...

Keyword(s):

Risk Assessment ◽

Sea Ice ◽

Bohai Sea ◽

Vulnerability Index ◽

Structural Vulnerability ◽

Liaodong Bay ◽

The Bohai Sea ◽

Oil Platforms ◽

Force Mode ◽

Ice Force

Abstract. Sea ice disasters seriously threaten the structural safety of oil platforms in the Bohai Sea. Therefore, it is necessary to carry out a risk assessment of sea ice disasters on oil platforms in the Bohai Sea. In this study, a risk assessment of sea ice disasters on fixed jacket platforms in Liaodong Bay, in the Bohai Sea, was performed in five steps. Firstly, the formation mechanisms of sea ice disasters were analyzed and the sources and modes of sea ice risks were summarized. Secondly, according to the calculation formulas of extreme ice force, dynamic ice force, and accumulated force, several ice indices such as thickness, motion, strength, period, and concentration were proposed as the hazard indices, and corresponding values were then assigned to the proposed indices based on ice conditions in the Bohai Sea. Thirdly, based on four structural failure modes – structural overturning by extreme ice force (Mode 1), structural fracture failure caused by dynamic ice force (Mode 2), the damage of facilities caused by dynamic ice force (Mode 3), and structural function failure caused by accumulated ice (Mode 4) – the structural vulnerability index, overturning index, dynamic index, ice-induced vibration index, and function index were proposed, and corresponding values were assigned to the structural vulnerability index of fixed jacket platforms in Liaodong Bay. Fourthly, the weight of each risk index was determined according to previously recorded sea ice disasters and accidents, and the sea ice risk was then calculated with the weighted synthetic index method. Finally, with the above index system and risk assessment methods, the risk assessment of sea ice disasters on 10 jacket platforms in three sea areas in Liaodong Bay was carried out. The analysis results showed that efficient sea ice prevention strategies could largely mitigate the sea ice-induced vibration-related risks of jacket platforms in Liaodong Bay. If steady-state vibration occurs (usually in front of the vertical legged structure) or the structural fundamental frequency is high, the structural vulnerability is significantly increased and the calculated risk levels are high. The sea ice risk assessment method can be applied in the design, operation, and management of other engineering structures in sea ice areas.

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Suitability of locations in the Bohai Sea, China, for the exploitation of sea ice as a freshwater resource

Annals of Glaciology ◽

10.3189/2013aog62a304 ◽

2013 ◽

Vol 54 (62) ◽

pp. 267-272 ◽

Cited By ~ 2

Author(s):

Lantao Li ◽

Wei Gu ◽

Chengyu Liu ◽

Yingjun Xu ◽

Jinlong Chao ◽

...

Keyword(s):

Sea Ice ◽

Bohai Sea ◽

Mining Area ◽

Bohai Bay ◽

Liaodong Bay ◽

Gis Technology ◽

The Bohai Sea ◽

Freshwater Resource ◽

The Status ◽

Technological Level

AbstractBased on recent studies on sea ice and newly developed technologies, this paper examines the requirements and environmental factors for exploitation of sea ice as a freshwater resource. Considering the ‘mining’ of sea ice, the suitability of locations in the Bohai Sea, China, for exploitation was analysed and evaluated using GIS technology. The ice must be >10 cm thick, the intertidal zone must be narrow and the ‘mining’ area must have a water depth of at least 2 m. The sea areas with feasible resources are located mainly in the nearshore area of northern Liaodong Bay and in a narrow and long area along the coast of Bohai Bay. Most coastal areas of northern Liaodong Bay have favourable conditions, while Bohai Bay is widely constrained by unsuitable conditions. According to the status of the resources and the coastal environment conditions, the eastern and western coasts of northern Liaodong Bay are the most suitable areas for exploitation at the current technological level.

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Analysis of Influence Factors of GF-4 Registration Accuracy on Sea Ice Drift in the Bohai Sea

E3S Web of Conferences ◽

10.1051/e3sconf/201913101073 ◽

2019 ◽

Vol 131 ◽

pp. 01073

Author(s):

Ruifu Wang ◽

Pan Wei ◽

Yingjie Zhao

Keyword(s):

High Resolution ◽

Sea Ice ◽

Bohai Sea ◽

Time Interval ◽

Liaodong Bay ◽

Registration Accuracy ◽

The Bohai Sea ◽

Migration Direction ◽

Ice Drift ◽

Sea Ice Drift

The “GF-4” satellite is China’s first high resolution geostationary optical remote sensing satellite. It has the unique advantages of short imaging time interval (20s) and high resolution (50m). In order to analyze the effect of GF-4 satellite image registration accuracy on sea ice drift in Bohai Sea, firstly, the orthorectification of the 28 image data available from August 2016 to March 2018 in the Bohai Sea area was carried out. Then we selected the sea-land edge points as control points, and registration of two images which have the same time interval. Next, we recorded the marked same name points which searched from the bottom of Liaodong bay, east of Liaodong bay and west of Liaodong bay respectlly. We statisticed the direction and frequency of land point offset sub-regionally, then we created the rose plots and maked histogram of the offset of land point. The results show that, when the time interval is 4 hours and 24 hours, the dominant migration direction in the three regions in Liaodong bay is east; when the time interval is 1 minute, the dominant migration direction in Liaodong Bay bottom and Liaodong Bay west coast land is south, Followed by east and southeast respectively; the dominant migration in Liaodong Bay East Coast is north, followed by east; When the time interval is 3 hours, the dominant migration direction in west of Liaodong Bay, bottom of Liaodong Bay and east of Liaodong bay are east, west and south respectively, followed by southeast, east, southeast respectively. The land offset in three regions is major centralized distribution in a range which is from 60m to 80m. That is to say, the offset of land is basically equal to 1.2 times of pixels, and the maximum land offset is less than 2 times of pixels. Through statistical analysis, it can be seen that with the increase of time interval, the land offset will not change much. This study also paves the way for the study of the drift of sea ice.

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Observation of Sea Ice Drift Characteristics with Marine Radar Images on an Offshore Platform in the Bohai Sea

Journal of Waterway Port Coastal and Ocean Engineering ◽

10.1061/(asce)ww.1943-5460.0000646 ◽

2021 ◽

Vol 147 (4) ◽

Author(s):

Xue Long ◽

Xiaodong Chen ◽

Anliang Wang ◽

Yu Liu ◽

Shunying Ji

Keyword(s):

Sea Ice ◽

Bohai Sea ◽

Offshore Platform ◽

The Bohai Sea ◽

Radar Images ◽

Ice Drift ◽

Sea Ice Drift ◽

Marine Radar

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Spatio-temporal characteristics of the sea-ice volume of the Bohai Sea, China, in winter 2009/10

Annals of Glaciology ◽

10.3189/2013aog62a305 ◽

2013 ◽

Vol 54 (62) ◽

pp. 97-104 ◽

Cited By ~ 9

Author(s):

Chengyu Liu ◽

Wei Gu ◽

Jinlong Chao ◽

Lantao Li ◽

Shuai Yuan ◽

...

Keyword(s):

Sea Ice ◽

Bohai Sea ◽

Shortwave Radiation ◽

Laizhou Bay ◽

Bohai Bay ◽

Temporal Characteristics ◽

The Bohai Sea ◽

Ice Volume ◽

Radiation Theory ◽

Spatio Temporal

AbstractTo investigate the spatio-temporal characteristics of sea-ice resource, we used sea-ice volume to measure the amount of sea-ice resource in the Bohai Sea, China. The sea-ice area was extracted from Advanced Very High Resolution Radiometer (AVHRR) remote-sensing images using the zonal threshold method. The sea-ice thickness was estimated using a sea-ice model based on shortwave radiation theory and field measurements. The spatio-temporal characteristics of sea-ice volume were then analysed using GIS technology. The results indicate that the Bohai Sea experienced two sea-ice volume peaks in winter 2009/10. The largest sea-ice volume was in Liaodong Bay (∼80.26% of the entire sea-ice volume of the Bohai Sea). Bohai Bay had the second largest ice volume, and Laizhou Bay the smallest. The relationship between sea-ice volume and distance from shore is essentially exponential. The proportion of total sea-ice volume that is 0–10 km from shore is ∼42.43%, whereas the proportion that is 100–110 km from shore is only 0.002%.

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