海底管道在位稳定性研究

发布时间：2018-10-25 15:15

【摘要】：海底管道是海上油气田开发生产系统的主要组成部分,在海洋油气资源的开发中发挥着重大作用,被喻为海上油气田的“生命线”。海底管道的安全高效运行是油气田正常生产的重要保证。为保证海底管道的安全运行,最大程度地避免海底管道失效事故的发生,海底管道服役期运行结构安全成为各大国际石油公司关注的焦点。随着油气田开发水深的不断增加,深水海底管道面临诸多新的挑战,本文推导了深水管道沉降量计算公式,采用铺管时管道沉降的计算方法,研究了管道沉降理论计算方法与数值模拟方法的关系,并在此基础上给出了管-土相互作用摩阻力曲线。推导了竖向和水平向热屈曲的解析解,采用海底管道竖向和水平向热屈曲的有限元方法,研究了解析解法和数值模拟法的区别与联系。阐述了竖向和水平向热屈曲的防护措施,分析了压块保护法和枕木法控制管道竖向和水平向热屈曲的机理,并结合工程实例,验证了两种防护方法的实施效果。提出基于ARVM模型的滑坡分析方法,设计了混凝土联锁排以防护海底冲刷,并结合工程实例进行了分析。本文阐述了海底管道常用的检测与维修方法及适用范围,并结合具体工程实例给出了海底管道检测与维修的过程与步骤。通过研究得到以下结论:(1)管道直径和管重对沉降量的影响较大,管道沉降与管径成反比,与管重成正比;土体不排水抗剪强度对管道沉降的影响也不可忽视,随着土体强度的增加,管道沉降量呈指数衰减。当土体强度达到2.0kPa时,管道沉降量趋于一致。该结果与几内亚湾和安哥拉海域实际工程经验和现场实际观测数据相符。(2)无论是竖向热屈曲还是水平向热屈曲,屈曲变形都是基于管道的几何初始缺陷发展而来,且在管道中点处轴向应力(应变)和轴力最大;相比于有限元的模拟结果,解析解计算得到管道发生热屈曲的屈曲温差较大,二者最大相差20%。(3)枕木防护技术中,管道初始水平向位移越大,管道的临界屈曲荷载越低,且随着管道初始水平向位移的增大,管道壁厚对临界屈曲荷载的影响逐渐减弱。相同壁厚条件下随着双枕木间隔的增大,管道的临界屈曲荷载逐渐降低,降低幅度较均匀。(4)ARVM模型能实现边坡稳定性状态量化计算,在计算时模型采用的计算内核不同,所得预测结果的准确性也不同,且需先进行先导计算以确定最优超参数值;混凝土联锁排排首处块体的水流环境最为复杂,排首逆水面水流动态压力最大,容易产生掀起,边缘排体应适当增加厚度或增加流线设计,降低水流的冲击力度。(5)结合工程实例,详述了管道内检及外检的实用方法,依据管道监测结果对管道破损类型进行划分,建立了以破损类型为判断指标的管道破损程度分类方法,开展了与破损程度相对应的管道维修作业方法研究。
[Abstract]:Submarine pipeline is the main component of offshore oil and gas field development and production system. It plays an important role in the development of offshore oil and gas resources and is regarded as the "lifeline" of offshore oil and gas field. The safe and efficient operation of submarine pipelines is an important guarantee for the normal production of oil and gas fields. In order to ensure the safe operation of the submarine pipeline and avoid the failure accident of the submarine pipeline to the greatest extent, the safety of the operating structure of the submarine pipeline in service has become the focus of attention of the major international oil companies. With the increasing water depth of oil and gas field development, the deepwater submarine pipeline is facing many new challenges. In this paper, the formula for calculating the settlement of deep water pipeline is derived, and the calculation method of pipeline settlement when laying pipes is adopted in this paper. The relationship between the theoretical calculation method of pipeline settlement and the numerical simulation method is studied, and the friction curve of pipe-soil interaction is given. The analytical solutions of vertical and horizontal thermal buckling are derived. The difference and relation between the analytical method and the numerical simulation method are studied by using the finite element method of vertical and horizontal thermal buckling of submarine pipelines. The protective measures of vertical and horizontal thermal buckling are expounded, the mechanism of controlling vertical and horizontal thermal buckling of pipes by block protection and sleeper method is analyzed, and the effect of the two protection methods is verified by an engineering example. A landslide analysis method based on ARVM model is put forward, and concrete interlocking row is designed to protect seabed scour. In this paper, the commonly used detection and maintenance methods and the applicable scope of submarine pipeline are expounded, and the process and steps of submarine pipeline inspection and maintenance are given in combination with concrete engineering examples. The conclusions are as follows: (1) the influence of pipe diameter and pipe weight on the settlement is great, the pipe settlement is inversely proportional to the pipe diameter, and the influence of the undrained shear strength on the pipeline settlement cannot be ignored. With the increase of soil strength, the pipe settlement decreases exponentially. When the strength of soil reaches 2.0kPa, the settlement of pipeline tends to be consistent. The results are in agreement with the practical engineering experience and field observation data in the Gulf of Guinea and Angola. (2) both vertical and horizontal thermal buckling, buckling deformation is based on the initial geometric defects of the pipeline. The axial stress (strain) and axial force are the largest at the midpoint of pipeline. Compared with the simulation results of finite element method, the temperature difference of thermal buckling of pipeline is larger than that of finite element method. (3) in the technology of sleepers protection, the maximum difference between them is 20%. The greater the initial horizontal displacement, the lower the critical buckling load, and with the increase of the initial horizontal displacement, the influence of pipe wall thickness on the critical buckling load decreases gradually. Under the condition of the same wall thickness, the critical buckling load of the pipe decreases gradually with the increase of the double sleeper spacing. (4) the ARVM model can realize the quantitative calculation of the slope stability state. The accuracy of the predicted results is also different, and it is necessary to carry out pilot calculation to determine the optimal super-parameter value. The flow environment of the block at the head of the concrete interlocking row is the most complex, and the dynamic pressure of the reverse water flow is the largest, so it is easy to be raised. The edge discharge should increase the thickness or increase the streamline design to reduce the impact of water flow. (5) combined with engineering examples, the practical methods of pipeline internal and external inspection are described in detail, and the types of pipeline damage are classified according to the results of pipeline monitoring. The classification method of pipeline damage degree based on the damage type is established, and the pipeline maintenance operation method corresponding to the damage degree is studied.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE973.92

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