深海钢悬链线立管触底区管土相互作用试验研究
发布时间：2018-10-14 09:25
【摘要】：当前,我国深水油气开采的关键技术和国际发达国家相比还有一定差距,在富含油气资源的南海深水区至今尚无独立开采能力。海底管道作为深海油气资源运输的最佳方式,其动力铺设安全性、在位服役稳定性等是其关键技术瓶颈。 随着相对浅水区化石燃料的枯竭,越来越多储存在深海中的油气资源被广泛开发。在深水条件下,传统固定式生产平台的结构形式已经不再适用,而各种各样的浮式生产平台或船只越来越多的被采用,例如半潜式平台(Semi-submersible)和立柱式平台(SPAR)、浮式生产储运卸货装置(FPSO);除了浮式结构以外,一个完整的浮式生产系统(FPS)还包括锚泊系统和立管,立管是在海底井口和浮式平台之间运输烃类产品或者运出生产废液的主要手段,这些柔性浮式生产系统的引入推动了新型立管设计的发展。当前,与传统的垂直立管、柔性立管相比,钢悬链线立管SCR (Steel catenary riser))已经成为深水环境下油气运输的最有效方法,而对于立管疲劳的精确分析很大程度上取决于立管与海床土(TDP)的相互作用,因此,管土相互作用模型一直是近几年的研究重点。 本文首先数值研究了SCR的非线性动力响应,尤其是触底区(TDZ)的动力响应；然后通过大比尺室内试验来模拟SCR与典型粘土质海床的三维相互作用,通过对管道的一端施加循环运动来模拟动力管土相互作用,详细分析了沟槽形成过程、管线内力变化以及管底超孔隙水压力的发展,从管底超孔压累积的角度解释了管道埋深增加的机理,从极限破坏和疲劳破坏的角度为SCR的设计提供建议。另外,本文还研究了动力管土相互作用前后管底土体的强度变化,增加了对土体软化的认识。具体的工作包括以下内容： 1.采用Orcaflex有限元软件,结合水动力分析软件AQWA,以中国南海某一大型深水半潜式钻井平台为例,建立“半潜式平台-SCR-海床”的动力相互作用数值模型,考虑波浪、海流等环境因素的综合影响,研究SCR的非线性动力响应,尤其是触底区(TDZ)的动力响应,为室内大比尺试验提供参考。 2.针对粉质粘土海床,首次设计和建立大比尺海洋管道与软土室内模型试验,详细介绍了试验系统的组成及其功能和试验准备相关工作。 3.基于该大比尺三维土与结构相互作用模型试验系统,进行了一系列试验,主要研究触地段竖向管土相互作用,包括静力试验、动力循环试验以及动力循环结束后的T-bar试验。通过对位移、孔压、管道弯矩监测数据的分析,对软弱海床上的竖向管土行互作用的机理进行深入研究,揭示管道埋深增加的规律,研究土吸力对管道内力变化的影响,为SCR的触地段疲劳分析提供支持。
[Abstract]:At present, the key technologies of deep water oil and gas exploitation in China are still far from those in the developed countries, and there is no independent exploitation capacity in the deep water area of the South China Sea, which is rich in oil and gas resources. As the best way to transport deep sea oil and gas resources, submarine pipeline has the key technical bottleneck, such as safety of power laying and stability in service. With the depletion of fossil fuels in relatively shallow water, more and more oil and gas resources stored in the deep sea have been extensively exploited. In deep-water conditions, the structural forms of traditional fixed production platforms are no longer applicable, and a variety of floating production platforms or ships are increasingly used. For example, semi-submersible platform (Semi-submersible) and column platform (SPAR), floating production, storage and unloading device (FPSO);, in addition to floating structure, a complete floating production system (FPS) also includes mooring system and riser, Riser is the main means to transport hydrocarbon products or produce waste liquid between the bottom well head and floating platform. The introduction of these flexible floating production systems has promoted the development of new riser design. At present, compared with the traditional vertical riser and flexible riser, the steel catenary riser SCR (Steel catenary riser) has become the most effective method for oil and gas transportation in deep water environment. The exact analysis of riser fatigue depends largely on the interaction between riser and seabed soil (TDP), so the pipe-soil interaction model has been the focus of research in recent years. In this paper, the nonlinear dynamic response of SCR, especially the dynamic response of (TDZ) in the bottom contact region, is numerically studied, and then the three-dimensional interaction between SCR and typical clay seabed is simulated by a large scale laboratory test. By applying cyclic motion to one end of the pipeline to simulate the dynamic tube-soil interaction, the formation process of the grooves, the variation of the pipeline internal force and the development of the excess pore water pressure at the bottom of the pipe are analyzed in detail. The mechanism of pipe buried depth increase is explained from the point of view of superpore pressure accumulation at the bottom of the pipe, and some suggestions for the design of SCR are provided from the viewpoint of ultimate failure and fatigue failure. In addition, the change of soil strength before and after dynamic tube-soil interaction is studied, and the understanding of soil softening is increased. Specific work includes the following: 1. By using Orcaflex finite element software and hydrodynamic analysis software AQWA, a numerical model of dynamic interaction of a large deep water semi-submersible drilling platform in the South China Sea (South China Sea) is established. The numerical model of dynamic interaction of "semi-submersible platform-SCR- seabed" is established, and the wave is considered. The nonlinear dynamic response of SCR, especially the dynamic response of (TDZ) in bottom contact region, is studied by the combined effect of environmental factors such as current, which provides a reference for indoor large scale test. 2. Aiming at silty clay seabed, the laboratory model test of large scale offshore pipeline and soft soil is designed and established for the first time. The composition and function of the test system and the related work of test preparation are introduced in detail. Based on the large scale three-dimensional soil-structure interaction model test system, a series of experiments were carried out, including static test, dynamic cyclic test and T-bar test after the end of the dynamic cycle. By analyzing the monitoring data of displacement, pore pressure and pipe bending moment, the mechanism of vertical pipe-soil interaction on the weak seabed is studied in order to reveal the law of pipeline buried depth increase, and to study the influence of soil suction on the variation of pipeline internal force. To provide support for SCR contact fatigue analysis.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P756.2
本文编号：2270052
[Abstract]:At present, the key technologies of deep water oil and gas exploitation in China are still far from those in the developed countries, and there is no independent exploitation capacity in the deep water area of the South China Sea, which is rich in oil and gas resources. As the best way to transport deep sea oil and gas resources, submarine pipeline has the key technical bottleneck, such as safety of power laying and stability in service. With the depletion of fossil fuels in relatively shallow water, more and more oil and gas resources stored in the deep sea have been extensively exploited. In deep-water conditions, the structural forms of traditional fixed production platforms are no longer applicable, and a variety of floating production platforms or ships are increasingly used. For example, semi-submersible platform (Semi-submersible) and column platform (SPAR), floating production, storage and unloading device (FPSO);, in addition to floating structure, a complete floating production system (FPS) also includes mooring system and riser, Riser is the main means to transport hydrocarbon products or produce waste liquid between the bottom well head and floating platform. The introduction of these flexible floating production systems has promoted the development of new riser design. At present, compared with the traditional vertical riser and flexible riser, the steel catenary riser SCR (Steel catenary riser) has become the most effective method for oil and gas transportation in deep water environment. The exact analysis of riser fatigue depends largely on the interaction between riser and seabed soil (TDP), so the pipe-soil interaction model has been the focus of research in recent years. In this paper, the nonlinear dynamic response of SCR, especially the dynamic response of (TDZ) in the bottom contact region, is numerically studied, and then the three-dimensional interaction between SCR and typical clay seabed is simulated by a large scale laboratory test. By applying cyclic motion to one end of the pipeline to simulate the dynamic tube-soil interaction, the formation process of the grooves, the variation of the pipeline internal force and the development of the excess pore water pressure at the bottom of the pipe are analyzed in detail. The mechanism of pipe buried depth increase is explained from the point of view of superpore pressure accumulation at the bottom of the pipe, and some suggestions for the design of SCR are provided from the viewpoint of ultimate failure and fatigue failure. In addition, the change of soil strength before and after dynamic tube-soil interaction is studied, and the understanding of soil softening is increased. Specific work includes the following: 1. By using Orcaflex finite element software and hydrodynamic analysis software AQWA, a numerical model of dynamic interaction of a large deep water semi-submersible drilling platform in the South China Sea (South China Sea) is established. The numerical model of dynamic interaction of "semi-submersible platform-SCR- seabed" is established, and the wave is considered. The nonlinear dynamic response of SCR, especially the dynamic response of (TDZ) in bottom contact region, is studied by the combined effect of environmental factors such as current, which provides a reference for indoor large scale test. 2. Aiming at silty clay seabed, the laboratory model test of large scale offshore pipeline and soft soil is designed and established for the first time. The composition and function of the test system and the related work of test preparation are introduced in detail. Based on the large scale three-dimensional soil-structure interaction model test system, a series of experiments were carried out, including static test, dynamic cyclic test and T-bar test after the end of the dynamic cycle. By analyzing the monitoring data of displacement, pore pressure and pipe bending moment, the mechanism of vertical pipe-soil interaction on the weak seabed is studied in order to reveal the law of pipeline buried depth increase, and to study the influence of soil suction on the variation of pipeline internal force. To provide support for SCR contact fatigue analysis.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P756.2
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