【作者】 陈养厚；

【导师】 陈国明； 顾心怿；

【作者基本信息】 中国石油大学 ， 机械设计及理论， 2010， 博士

【摘要】 本文依托国家高技术研究发展计划(863计划)“近海石油老龄平台延寿技术研究”课题,进行滩海石油老龄平台维修方法及应用研究。借鉴国内外海洋平台维修的基本理论及关键技术,结合我国海上油田的实际状况,以及碳纤维维修加固混凝土结构的成功应用,研究和开发老龄平台延寿服役的安全保障维修技术,通过试验、理论研究、数值计算和计算机仿真,在老龄平台的维修装备工艺设计改进、滩海平台的桩基冲刷机理及防治、新材料碳纤维平台维修、平台的维修分级、优化、维修策略以及老龄平台的延寿利用上取得较大的研究进展。主要研究成果总结如下:1老龄平台维修过程及加固方法老龄平台在服役的阶段内,影响其寿命的因素主要如下方面:疲劳载荷、坠物、船只碰撞、腐蚀、安装导致破坏、焊接制造缺陷、爆炸、海冰、生产过程载荷以及设计缺陷等,针对上述影响因素及其导致后果,平台的维修方法有构件去除、干焊、湿焊、灌浆、焊缝增强以及复合材料加固等,对比研究现有修理方法的优缺点,并结合胜利滩海油田的工程实际进行研究。结合小尺度模型试验,研究设计了浅海潜水伞及复杂节点简易焊接罩,通过理论分析、有限元计算以及实验验证,这两种装备经济可行,安装施工方便,研究了平台维修方法卡箍的类型及特点,得到卡箍设计流程规范。2滩海石油平台桩基冲刷防治平台桩基冲刷给平台安全运营带来隐患,不仅仅使平台倾斜力矩增加,而且平台附属管线易于折断,若根本上改变周围外界条件(波浪、海流大小以及周期等参数),从而减轻桩基的冲刷,具体实施起来存在很大困难,研究设计了导流法及阻流自埋法的冲刷防治方法,利用流体计算软件Fluent进行装置效果的仿真模拟,通过着手于引起泥沙起动运移的各种因素,采用正交试验法进行模拟的设计、分析,减少模拟仿真次数,提高模拟效率,有效分析模拟试验中影响装置主要因素,找出其变化趋势,并进行装置的设计优化。改变桩基周围局部流场,降低泥面桩基处流体质点流速的思路,是一种经济可行的桩基冲刷防治办法。3碳纤维在老龄平台维修的应用老龄平台维修加固工艺的发展,可通过对现有维修加固手段的研究提高而提高维修加固质量及经济性,另外一个方向是碳纤维增强复合材料(Carbon Fiber Reinforced Polymer,简称CFRP)的使用,对碳纤维的力学特性进行理论探讨,并就单向碳纤维布加固平台的工艺方法进行了研究,提出相应的施工方法,对碳纤维加固带裂纹金属杆件进行疲劳试验,试验结果表明,碳纤维对裂纹构件的维修加固,可有效提高其疲劳寿命。对不同的平台构件加固提出不同纤维走向的加固方法,对碳纤维预应力加固平台节点进行探讨。研究发现,预应力的施加,可以抵消一部分的内力,也可以有效的缓解残余应力和应力集中的情况,减小裂纹应力强度因子。4滩海老龄平台维修策略、管理及延寿应用平台维修是维持或恢复平台到一种完成所需功能的状态。通过有效地决策规划维修工作的内容和周期,以减少不确定性,通过执行维修来实现成本控制。从一定的技术经济因素来考虑,对所进行的维修方式和程度作出规定。在对平台的修理进行分级的基础上,相应的对平台进行维修级别分级。平台的修理级别分析,平台可靠性分析以及平台可维修性分析,其目的是有利于维修的实施,且可对后续平台的设计以及建造提供修改建议。通过对平台系统串并联的关系计算,可获得整个平台或功能组件的总体失效概率,通过对比组件或构件的临界重要性,获得故障组件的维修先后次序,为进一步的维修提供决策依据。通过各个组件的失效度以及修复率进行Markov分析,计算平台系统的每一状态时间,获得平台可靠度随着时间变化的关系,据此制定科学的维护方法,为进一步的维修优化提供判断的依据。通过对平台后期有效利用及延寿使用,可大大节约成本,进行资源的有效利用。通过对部分平台进行计算,通过适当的维修,可以使平台服役更长的时间。针对某平台进行风力发电,利用有限元进行计算,结果说明平台经过适当的维修加固,对于风电基础应用,其强度刚度及疲劳性能满足需求。提出的方法对今后我国日益增多的浅海钻采老龄平台的处置具有一定的指导意义。更多还原

【Abstract】 The dissertation focuses on maintenance methods and its applications for shallow water aged oil platform, which is a part of the“863”High Technology Research and Development Program of China (No.2006AA09Z355).The study is based on fundamental theory of offshore platform repairing and the key technology in china and abroad. Maintenance methods and applications for shallow water oil platform is investigated systemically based on theoretical research, numerical calculation and computer simulation, and much progress is achieved including improving of maintenance equipments and technology of aged offshore platform, scour mechanism of shallow water platform pile and its preventions, new material used in platforms repairing, classificatiaon of platform mainterance, optimization and its maintenance strategy, disposal and utilization of aged offshore platform, and so on.The main works are summarized as follows:1 Techniques and Processes of Strengthening, Modification and Repair for Aged Offshore PlatformThere are some factors to shorten the service life of offshore platform, which can be summarized as these categories: fatigue loads; dropped objects; vessel collision; corrosion; damage during installation; welding and/or fabrication fault; explosions; ice; build-up of drill cuttings; under-design. The factors and their results lead to a requirement for strengthening, modification and repair as follows: remove damage; dry welding; wet welding; grout filling; weld improvement; composites and so on. A comparative study on advantages and disadvantages of present repair methods were put in practice with the engineering practice of ShengLi shallow water oil field. A simple steel habitat is designed. The installation and construction of the habitat is convenient. Theory analysis and ANSYS finite element calculation show that the habitat is not restricted to depth of water. Clamping technology is studied and the design process for clamps is obtained.2 Scour Prevention Methods for Offshore Platform of Shallow Water Oil FieldScour can result in removal of vertical and lateral support for foundations, causing undesirable settlements of pile foundations and overstressing of foundation elements. It not only can increase loads on platform, but also can cause production line of jacket platform easily to fracture. It is difficult to change the external environment conditions(such as wave, current and periods) to prevent scour. Prevention methods of fluid diversion and self-bury are designed. Methods of these two scour prevention are simulated by Fluent to find out how can the parameters affect the purpose of prevention. The devices are optimized by the simulated results. The factors of sands and silts’ movement are considered. And the experiment of orthogonal method is used in simulation design and analysis. Results obtained from the computer models have demonstrated that the combination of CFD simulation and orthogonal design is suitable for the scour prevention. The idea of changing local flow field around the pile is an economic practicable method.3 Carbon Fiber Used in Maintenance of Aged Jacket PlatformTo improve the quality and economy of strengthening, modification and repair techniques of aged offshore platform, developing the present processes and introducing a new material called Carbon Fiber Reinforced Polymer(CFRP) are prefered. Mechanical properties of carbon fiber are studied theoretically and strengthening processes with unidirectional carbon fiber sheets are discussed. A new method of its application in strengthening platform components is brought forward. Strengthening used prestressed carbon fiber sheets are analysed with crack stress intensity factors. And some interesting results are obtained.4 Maintenance Strategy, Management and Maintenance Program Optimization of Offshore Platform and Prolong Aged Offshore Platform’s LifeOffshore platform maintenance means keeping or restoring the platform in the required state. The cost can be controlled by carrying out maintenance in premeditated plane and effective decision making of repair contents and repair cycle. Considering certain technical factors and economic factors, style and degree of repair are prescribed. Classification of offshore platform maintenance is made based on the Level of Repair Analysis(LORA). Level of Repair Analysis(LORA), Reliability Analysis(RA) and Maintainability Analysis(MA) are beneficial to implementation of repair. And it can give some advices to design and construction of a new platform to increase availability. The whole failure probability can be obtained by systemic connection in series or parallel and their calculation. Maintenance sequence of faulty components can be gained through comparison between their critical importance. And further maintenance optimization can be done with the results. The platform reliability along with the time variation can be obtained through the anlysis of failure ratio and repair rate with Markov analysis.The effective use of aged platforms are not only meet the standard of the environmental but also save the cost of oil production. An example calculation of aged platform for wind power generation is given. The method of reconstruct for other use have some practical value for real processing and guiding significance for offshore platform disposal.更多还原