Abstract: Design of wellhead protector system against ice loading is an important problem in oil development in shallow waters in Liaodongwan, Bohai Gulf. To investigate the stress state of the developed protector system using the riser to directly resist ice loading, types of joint three dimension finite elements and many boundary elements are used to model the layers of steel pipes and cement or concrete to establish the FE structural model of the system. The constraint conditions of the soil deposits to the structures are modeled by finite difference method. An ice sheet of 60mm thickness in extreme conditions is supposed to act on the thickened riser. The detailed analysis of stresses and displacements of the structure shows that the maximum displacement is at the top of the structure and the maximum stress in the top round plate connecting the riser and the outermost casing, with all the displacements and stresses in the system being in the allowed ranges. It is seen that the cemented concrete layers between the casings take very active part in increasing the strength of the structure.

Key words: wellhead protector system, riser, sea ice, finite element, boundary element, finite difference method

摘要： 对辽东湾浅海单井井口保护装置采用隔水套管直接抗冰的可行性进行了研究.采用多种三维混合单元建立了一典 型井口装置的有限元计算模型,该模型利用有限差分的原理真实地反映了地层对结构的约束.计算结果表明,在辽东湾浅 海的60cm单层平整冰作用下,结构的位移和应力都在许可范围之内,最大位移为结构的顶部,最大应力发生在隔水套管 与表层套管的上部连接环板上,而隔水套管内加固的水泥层对增加结构的强度、抵抗外载荷的作用起了不可忽视的作用. 计算结果和现场两年多的应用表明,用增厚的隔水套管直接抗冰是可行的.

关键词: 井口装置, 隔水套管, 海冰, 有限元, 有限差分法