深水油气管道天然气水合物聚集和壁面沉积微观力学机制研究

Hydrate blockage resulting from hydrate formation presents a key flow assurance issue in deep water oil and gas transportation lines. Understanding the plugging mechanism of hydrate is the prerequisite and the key for hydrate risk management. The traditional macro tests established the basic patterns of hydrate blockage; however, it is difficult to reveal the control mechanisms of the plugging through traditional test methods. As hydrate blockage is caused because of its force situation, investigating the micro mechanical characteristics of hydrate agglomeration and deposition can break through the limitations of traditional macro test, essentially reveal the control mechanisms. For the oil-dominated and gas-dominated systems, the key mechanical parameters involved in hydrate agglomeration and deposition are systematically investigated using self-built micro mechanical apparatus. Meanwhile, the theoretical models for hydrate-hydrate cohesion force and hydrate-wall adhesion force can be proposed by combining the analysis of interfacial parameters, and the mechanisms of hydrate agglomeration and deposition will be clear. Furthermore, combining the analysis of flow field in pipelines, the models for calculating the critical size of hydrate agglomeration, as well as the critical condition for hydrate accumulation or detachment, are proposed. This project can develop a prediction theory for evaluating hydrate agglomeration and wall deposition in pipelines, which can provide guidance to the establishment of hydrate prevention strategies, and thus improving hydrate risk assessment and management theory.

天然气水合物生成引发的管道堵塞成为当前深水油气集输流动保障所面临的关键问题。明确水合物的堵塞机理是实施风险管理策略的前提和关键。传统宏观测试确立了水合物堵塞的基本模式，却难以揭示其内在的控制机理。基于水合物堵塞是其受力状况具体体现的事实，本项目以水合物聚集和壁面粘附中的微观受力特性为研究出发点，克服传统宏观测试的局限性，从本质上阐述其控制机理。针对油、气集输体系，构建水合物作用力测试装置，探索水合物聚集和壁面粘附沉积涉及的关键力学参数及影响因素；结合界面特性参数分析，建立水合物微观聚集力和壁面粘附力理论模型，揭示水合物的聚集和壁面粘附机制；综合管道流场分析，建立水合物聚集体临界尺寸和壁面水合物积聚/脱离临界条件预测模型。本项目可形成一套定量评价管道水合物聚集和壁面沉积的预测理论，指导水合物堵塞防治策略的制定，完善水合物风险评估与管理理论。

天然气水合物生成引发的管道堵塞作为当前深水油气集输面临的主要问题，制约着深水油气田高效开发的进程。水合物颗粒聚集和壁面粘附沉积作为导致管道堵塞的核心环节，其作用机制尚不明确。本项目以水合物聚集和壁面粘附沉积中的微观受力特性为研究出发点，自主研制了水合物微观聚集力和壁面粘附强度测试装置，针对油、气相体系，开展了系统的水合物壁面生长形态、壁面粘附强度、水合物颗粒-液滴聚集力、水合物颗粒-壁面粘附力测试实验，结合界面张力和壁面润湿性等参数的测试，探索分析了相关因素的影响机制；耦合液滴壁面粘附功和水合物转化率，构建了壁面生长水合物粘附强度预测模型，揭示了其粘附机制和控制因素，基于钟摆悬滴模型和水合物壳理论，考虑液桥固化，建立了水合物颗粒聚集作用力和壁面粘附力理论模型，明确了颗粒聚集的主控作用力；在此基础上，综合管道流场分析，构建了壁面生长水合物剥离临界条件预测模型，建立了CFD-PBM耦合模型，实现了管道内水合物颗粒聚集过程的数值模拟及相关因素的影响分析。本研究开展的系统测试为管道水合物堵塞风险的定量评估提供了大量基础数据，聚集和粘附沉积机理的明确为水合物堵塞防治方法的制定提供了方向与理论依据，构建的颗粒聚集力和沉积层粘附强度预测模型是对毛细液桥理论和固-固粘附理论的重要补充和完善，自主研制的系列水合物微观作用力装置可望在相关领域推广。