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A dynamic numerical analysis model for hang-off evacuation down-hole riser was established with coupling the longitudinal and transverse deformation. The hard hang-off and soft hang-off boundary conditions were given considering the horizontal evacuation and vertical heave movement of the platform. The down-hole riser model was discretized by the finite element method and solved by the Newmark-β method. An experiment for the hang-off riser was conducted to verify the accuracy of the numerical model. For a deep-water well in the South China Sea, the dynamic characteristics of hard hang-off and soft hang-off risers coupling the longitudinal and transverse deformation were analyzed. The research results show that the lateral deformation of the hang-off evacuation riser presents a wave shape, and the vertical deformation vibrates periodically with the platform heaving. The maximum lateral and longitudinal displacements of the down-hole risers appear at the bottom of the riser under both hard and soft hang-off conditions. The displacement of the down-hole riser under the hard hang-off condition is small near the top, where the bending moment reaches a maximum value. The displacement of the down-hole riser near the top increases sharply under the soft hang-off condition, but the maximum bending moment appears near the water surface. The range of longitudinal displacement envelope of the hang-off evacuation riser increases gradually from top to bottom, while the range of axial tension envelope increases gradually from bottom to top. Besides, the minimum tension of the down-hole riser under hard hang-off conditions is negative near the top, where obvious axial compression with the risk of buckling failure appears.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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