半潜式钻井平台工作水深及平台吃水变化对平台气隙响应的研究

发布时间：2019-03-22 10:14

【摘要】：保持足够的甲板气隙高度以减少甲板上浪的概率是确保半潜式钻井平台结构安全和正常作业的必要条件，需要在平台设计和基于作业地点的评估过程中进行分析计算。半潜式平台是浮式海洋结构物，根据波浪势流理论，平台受到的波浪力可分解为辐射和绕射两种作用力，平台在这些力的作用下会发生运动，此外随着波浪的运动波浪表面高度也在不断变化，为避免甲板遭受波浪抨击，应保证平台甲板始终高于波平面。所谓气隙就是平台甲板底部与波浪表面之间的垂向距离，本文针对波浪对平台运动及气隙的影响进行了较为深入的研究。在论文的开始部分，对波浪理论进行简单的回顾和介绍；在论文的第二部分，结合一座半潜式平台的算例，对随机波浪下的结构运动和气隙响应进行了分析和研究。本文的主要研究方法为采用边界元数值法计算出算例平台的运动响应函数和设定计算位置点的波面升高响应函数，将二者叠加求得给定点的相对波面升高响应函数，结合波浪谱并根据线性变换原理计算得到给定海况下的谱函数，以3小时为统计时长，对平台的气隙响应进行了统计预报。文章还对工作水深、平台吃水、波浪周期和浪向等可能影响气隙的参数进行了深入的研究，，给出了平台设计时需要重点关注的气隙探测点。本文在波浪模型和平台运动模型上仅考虑一阶绕射，不考虑二阶及更高阶绕射，并且用不对称扩大因子对所计算的波面升高进行修正，相对于二阶及高阶计算，简化了计算并基本符合工程应用需要。
[Abstract]:The probability of maintaining sufficient deck air gap height to reduce the wave on the deck is the necessary condition for ensuring the safety and normal operation of the semi-submersible drilling platform, and it is necessary to carry out the analysis and calculation in the platform design and the evaluation process based on the operation site. The semi-submersible platform is a floating marine structure. According to the wave potential flow theory, the wave force of the platform can be decomposed into two kinds of forces of radiation and diffraction, and the platform can move under the action of these forces, In order to avoid wave attack on the deck, it is to be ensured that the platform deck is always higher than the wave plane. The air gap is the vertical distance between the bottom of the deck and the surface of the wave. In the beginning of the paper, a brief review and introduction of the wave theory is made. In the second part of the paper, the structural motion and the air gap response under the random wave are analyzed and studied in a case of a semi-submersible platform. The main research methods of this paper are to use the boundary element method to calculate the motion response function of an example platform and to set the wave surface elevation response function of the calculated position point, and the relative wave surface elevation response function of the given fixed point is obtained by the superposition of the two. The spectrum function of a given sea condition is calculated according to the wave spectrum and calculated according to the linear transformation principle, and the air gap response of the platform is counted according to the statistical time period of 3 hours. The paper also studies the parameters of the air gap, such as water depth, platform draft, wave period and wave direction, and gives the air gap detection which needs to be focused on the design of the platform. In this paper, only the first order diffraction is considered in the wave model and the platform motion model, and the second order and higher order diffraction are not considered, and the calculated wavefront elevation is corrected by the asymmetric expansion factor, and the calculation is simplified and the basic conformity with the project shall be simplified with respect to the second order and higher order calculation.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U674.381

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