海底管道沙粒侵蚀的机理、特性及分析模型

Due to several features of the transportation of deepwater hydrocarbon reserves in the South China Sea, such as cold temperature, high pressure and low levels of sulfide, the sand erosion becomes the predominant factor that causes the internal damage of subsea pipelines. The existing erosion models are all empirical or semi-empirical ones, which cannot be broadly accepted for prcdicting the erosion results. Furthermore, the mechanism and the whole process of sand erosion are not correctly reflected in these models. Based on model experimental study, the present project aims at exploring the mechanism and property of sand erosion of subsea pipelines. Three main contents will be studied, i.e., the random motion behavior of solid particle in the single-phase turbulence flow field, the motion behavior of solid particle in the multiphase-flow pipeline, and the cumulative erosion due to the impacts of massive particles. A new erosion model for subsea pipelines will be proposed based on the probabilistic motion model for soild particle. The researches described in the project are distinguished from the existing erosion models in three features, including the random motion of soild particle resulting from turbulence, the sand erosion model in different multiphase patterns, and the accurate prediction of the erosion profile especially the maximum erosive area of various pipe components. The flow assurance is a key technology in the deepwater oil and gas industry. Being an important topic of flow assurance, the research of sand erosion in China is still in its initial stage. Systematically studying the sand erosion of subsea pipelines is cruicial and urgent for enhancing the technology of flow assurance and promoting the innovative research and development of ocean engineering in China.

南海深水油气的输送具有低温、高压以及油质含硫量低等特点，沙粒侵蚀将是导致海底管道内部损伤的主要原因。国际上已有的沙粒侵蚀分析模型未能反映沙粒侵蚀破坏的机理及完整过程，这些经验或半经验模型均存在一定的适用范围。本项目以模型实验为基础，探究海底管道沙粒侵蚀的机理和特性，研究单相紊流流场中沙粒运动规律、多相流管道中沙粒运动规律和大规模沙粒撞击管壁的整体损伤效应，并以沙粒概率运动模型为基础建立起管道沙粒侵蚀分析模型。与国际上同类研究相比，本研究在紊流沙粒概率运动模型、多相流沙粒侵蚀模型以及管道最大侵蚀部位精确预测等方面具有显著特色。流动保障是海洋油气开发和利用的关键技术，作为流动保障的重要课题，管道沙粒侵蚀研究在国内仍处于空白或起步阶段，全面开展该研究对于提升国内的流动保障水平以至推动我国海洋工程技术的自主研发，具有重要而深远的意义。

管道内固体颗粒侵蚀是海洋油气开发流动保障领域的一个重要问题，涉及复杂的管内多相流、颗粒运动和跟踪以及管壁材料侵蚀损伤。本项目通过发展管道内湍流流场的概率场描绘方法、以及颗粒随机性运动规律分析模型，建立起全新的气液环状流和管道颗粒侵蚀概率分析模型，深入探究了气液环状流机理特性和管道颗粒侵蚀的机理及规律。在数值模拟方面，发展了管道颗粒侵蚀数值分析模型，可用于长直管道和弯头，以及气、液管道和气雾流、环状流管道。在实验研究方面，搭建起管道沙粒侵蚀模型实验系统，建立了相关实验技术；提出了管道沙粒侵蚀模型实验相似准则，运用该准则能合理有效地从模型试验预测出对应于实际工程的侵蚀结果。通过对管道内颗粒侵蚀问题开展全面、深入的理论、实验和数值模拟研究，建立起在国际上具有特色的、较为完整的理论模型和分析方法，取得了丰硕的学术成果，发表在相关领域的国际顶尖学术期刊。这些工作对于繁荣管道内多相流及颗粒侵蚀问题的科学研究具有重要意义，也有助于推动流动保障工程技术的进一步发展和完善。