固态流化采掘海洋天然气水合物藏的水平管段固相颗粒运移特征

Migration characteristics of solid-phase particles in horizontal pipes in the exploitation of marine gas hydrate reservoirs through solid fluidization

为了弄清在固态流化采掘条件下,海洋非成岩天然气水合物(以下简称水合物)藏固相颗粒在水平管段内的运移规律,基于液固两相流模型,采用Fluent软件耦合EDEM软件模拟了在水平管段不同液相速度、不同粒径、不同丰度下的水合物固相颗粒运移特征,并采用大型固态流化采掘物理实验模拟工具对数值模拟结果进行验证。研究结果表明:(1)单颗粒水合物在水平管段中的运移方式以跃移和蠕移为主,水合物颗粒群在水平管段中的运移方式受水合物丰度、液相速度、管径、水合物固相颗粒粒径影响较大;(2)当水合物丰度较低、颗粒粒径较大、液相流速较低时,固相颗粒运移方式主要以跃移、蠕移为主;(3)当水合物丰度较高、颗粒粒径较小、液相流速较大时,固相颗粒运移方式主要以悬移为主;(4)提高液相进口速度是提高水平管内净化效果的有效手段。结论认为:(1)选取破碎效果较好的二级破碎工具可以提高水平管段固相颗粒群的净化效果;(2)水合物固态流化开采水平管段内压力降主要受液相流速影响较大,在满足举升泵设备负荷前提下,应调整注入排量来达到合适的液相流速。

This paper aims to find out the migration law of solid phase particles in horizontal pipe sections in the exploitation of natural gas hydrate resources through solid fluidization.First,based on the liquid–solid two-phase flow model,the Fluent software was applied to couple with the EDEM software to simulate the migration of solid hydrate particles transported through horizontal pipe segments with different liquid phase velocities,various particle sizes and hydrate abundances.Then a large physical experimental simulator for solid fluidization exploitation was adopted to validate the results of numerical simulation.The following findings were obtained.(1)The main migration modes of single-particle hydrate in horizontal section are saltation and creep.And the migration pattern of hydrate particle clusters in horizontal pipe section was greatly affected by hydrate abundance,liquid phase velocity,pipe diameter and solid particle size;(2)When the hydrate abundance and the liquid phase velocity are higher and the pipe diameter is small,the migration modes of solid particles are dominated by saltation and creep movement;conversely,the migration mode is mainly suspension movement.(3)To increase the inlet liquid velocity is an efficient means to improve the purification effect in horizontal tube sections.It is concluded that choosing the secondary crushing device with better crushing effect can improve the purification effect of solid particle clusters in horizontal pipe section.Besides,the pressure drop in the horizontal pipe section is mainly affected by the liquid velocity.In the prerequisite of meeting the lifting pump equipment load,the liquid velocity should be adjusted to achieve the appropriate liquid phase flow rate.