半潜式平台运动响应特性研究及设计方案优选

发布时间：2018-03-30 23:22

本文选题：半潜式平台　切入点：水动力分析　出处：《江苏科技大学》2016年硕士论文

【摘要】：半潜式平台作为典型深海平台,凭借其抗风能力较强,工作水深适应范围广,钻井能力强等诸多优点在海洋石油勘探开发中得到了广泛应用,与浅水固定式平台不同,深水浮式平台在海洋环境中具有十分复杂的运动响应特性,且浮式平台的运动响应直接关系着人员安全、设备安全、正常生产以及钻采方式等各个方面。因此,准确预报半潜式平台水动力及运动响应对平台钻井开采工作具有十分重要的意义。本文分别采用基于势流理论的软件AQWA及基于粘流理论的软件FINE/Marine对半潜式平台的水动力、运动响应、气隙等进行了数值模拟及分析,并以半潜式平台的垂向位移为主要目标进行了平台的改型设计及方案优选。应用AQWA软件的LINE模块对半潜式平台的水动力进行频域分析,得到附加质量、辐射阻尼及不同波浪入射角下的幅值响应算子、一阶波浪力与二阶波浪力等水动力系数;应用FINE/Marine软件实现平台受迫正弦运动,通过观测平台运动曲线及运动方向的受力曲线,经数学模型换算得到平台的粘性附加质量。应用AQWA软件的DRIFT模块,开展了5种海况、5个浪向角共计25种工况下的半潜式平台运动响应数值模拟,得到平台六自由度运动及加速度的历时曲线,并对25种工况下的计算结果按照浪向角和波浪参数进行分类分析,结果显示平台纵荡与横荡性能满足规范要求,而平台垂荡运动幅值较大,最大值达到了15.7m,超过了规范要求,平台横摇极值达到了28°,艏摇达到了12°,均超过规范规定的10°,平台的纵摇性能满足规范要求,平台横荡加速度达到1.5m/s2,纵荡加速度达到1.7m/s2,横向运动加速度相对较大,会造成人类劳动的不适,而垂荡运动加速度符合规范的要求。通过自由衰减数值模拟的方法获取半潜式平台粘性阻尼,将其人工添加至势流软件AQWA,对平台添加阻尼后的运动响应进行预报,分析粘性阻尼及势流阻尼对半潜式平台运动的影响。结果显示增加粘性阻尼后,纵荡方向运动平均减小6%,横荡方向平均减小26%,垂荡方向平均减小16%,横摇方向平均减小68%,纵摇方向平均减小23%,艏摇方向平均减小20%;添加粘性阻尼后,除垂荡方向运动较大外,其余自由度的运动皆满足规范要求,所以粘性阻尼的影响不容忽视。基于粘流与势流软件,并通过自编程序分别对半潜式平台的气隙进行了统计分析并对比,为便于观测半潜式平台在各工况下的气隙变化量,在平台下甲板上布置了34个观测点,观测点主要位于平台下甲板的边缘、立柱的周围。结果显示平台出现负气隙的区域主要发生在平台下甲板的边缘处,且基于粘流软件计算出的半潜式平台负气隙量普遍大于势流理论的结果。根据半潜式平台垂荡运动公式及相关经验,以平台垂向位移为主要目标,综合考虑横摇、纵摇的幅值,对平台提出相关改型方案,包括下浮体间距、下浮体端面形状、下浮体形状、立柱截面形状、立柱截面面积、平台吃水、增加垂荡板等,所有改型方案均保证平台的排水量、转动惯量及重心位置不变,然后对每一种方案的运动性能进行分析,并与原型进行对比,最终优选出最优方案,且针对最优改型方案进行计及粘性的运动性能研究,其运动响应结果均满足规范要求。
[Abstract]:Semi submersible platform as a typical deep-sea platform, with its strong wind resistance, water depth and adapt to a wide range of advantages of drilling ability has been widely used in offshore oil exploration and development, and the shallow water fixed platform, floating deepwater platform response is very complex movement in the marine environment, and the response of floating platform motion is directly related to the safety of personnel and equipment safety, normal production and drilling methods and other aspects. Therefore, the platform drilling work has very important significance to accurately predict the response of semi submersible platform hydrodynamics and motion. This paper uses the theory of potential flow and hydrodynamic software AQWA software FINE/Marine, semi submersible the viscous flow type platform based on the theory of motion response based on the air gap was simulated and analyzed, and the semi submersible platform vertical displacement as the main target. Optimization and retrofit design scheme of the platform. The frequency domain analysis of hydrodynamic module of LINE semi submersible platform using AQWA software to get the added mass and radiation damping, the amplitude of different incident angle of wave response of the operator, the first-order wave force and the two order wave force and hydrodynamic coefficient; application of FINE/Marine software platform forced sinusoidal exercise, stress curve through the observation platform motion curve and the direction of motion, viscous added mass is obtained by the mathematical model of platform conversion. The DRIFT module by using AQWA software, carry out the 5 kinds of the sea, 5 wave of semi submersible platform movement angle total of 25 kinds of conditions in response to numerical simulation, get the duration curve of platform six freedom of movement and acceleration, and calculate the 25 conditions according to the result of wave direction and wave parameters are classified and analyzed, results show that the platform surge and yaw performance can meet the requirements of standard, and Heave amplitude is large, the maximum value reached 15.7m, exceeding the standard requirement, the platform roll extreme reached 28 degrees, the swing was 12 degrees, more than standard 10 degrees, pitching performance can meet the requirements of specification of the platform, the platform yaw acceleration reaches 1.5m/s2, surge acceleration reached 1.7m/s2. The transverse acceleration is relatively large, can cause human labor discomfort, and the heave acceleration meets the requirement of specification. For semi submersible platform by viscous damping method of free attenuation of numerical simulation, the artificial potential flow is added to the AQWA software on the platform after adding damping motion response prediction, analysis of the effect of viscous damping and the potential damping of semi submersible platform motion. The results showed that adding viscous damping, surge direction decreases 6%, sway direction decreases 26%, heave direction decreased 16% in average, rolling direction average reduction 68%, the average pitch direction decreases 23%, yaw direction average decrease of 20%; adding viscous damping, the heave motion direction is large, the degrees of freedom of movement of all meet the standard requirements, so the influence of viscous damping can not be ignored. The viscous flow and the potential flow based on the software, the program compiled by the authors on the air gap respectively. Submersible platform were analyzed and compared, the air gap variation to facilitate the observation of semi submersible platform under different working conditions, the layout of the 34 observation points in the platform deck, observation platform is mainly located in the edge of the deck around the column. The results show that the platform gap occurs mainly bloom at the edge of the deck in the platform, and based on the semi submersible platform negative clearance viscous flow calculated by the software is generally greater than the potential flow theory. According to the results of the semi submersible platform heave motion formula and relevant experience, the vertical displacement is the main platform To the target, considering rolling, pitching amplitude, and puts forward relevant modifications on the platform, including floating body spacing, face downward float body shape, floating body shape, column shape, column section area, platform draft, increase Heave Plate, displacement are guaranteed all modifications of the platform, and inertia the position of the center of gravity and rotation invariant, the motion performance of each scheme are analyzed, and compared with the prototype, and select the optimal scheme of motion performance and considering viscous for optimal retrofit program, its motion response results meet the requirements of specification.

【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U674.38

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