含蜡和防聚剂体系天然气水合物浆液生成及流动特性

摘要

研究含蜡和防聚剂体系天然气水合物浆液生成及流动特性,对于在深水含蜡油气田实施水合物浆液输送技术、解决海底管道多相混输流动保障问题具有重要意义.本文基于高压水合物环路开展的蜡晶存在与否,对含防聚剂天然气水合物浆液生成及流动影响进行实验,对比分析所获得的实验温度、压力、水合物生成体积分数、流量和压降等宏观参数变化,同时结合颗粒录影显微仪(PVM)、颗粒粒度分析仪(FBRM)等微观数据分析,研究了蜡晶对含防聚剂的天然气水合物浆液生成及流动特性的影响规律.结果表明:相比于无蜡体系,含蜡体系中蜡晶会在防聚剂的作用下吸附在油水界面,减小气水成核反应表面积,增大水合物生成传质阻力,从而抑制水合物生成成核,延长水合物生成诱导期,并使水合物生成量降低;蜡晶与水滴之间团聚物的形成,促进了其与水合物颗粒间的聚并,浆液体系黏度增加,流动性显著下降.含蜡和防聚剂体系天然气水合物浆液生成及流动涉及学科复杂,未来仍需基于已获得的蜡与水合物相关独立研究成果,进一步探讨蜡与水合物之间的耦合作用机理.%The study of characteristics of natural gas hydrate slurry formation and flow with wax crystals and anti-agglomerates,is of great significance for the implementation of hydrate slurry technology in deep water waxy oil and gas fields to solve multiphase flow assurance issues. Based on the experiments of hydrate slurry formation and flow with and without wax crystals in the presence of anti-agglomerates carried out in a high-pressure hydrate flow loop,the variations of temperature, pressure,hydrate formation volume fraction,flow rate and pressure drop were compared and analyzed, and the effect of wax crystals on the characteristics of natural gas hydrate slurry formation and flow in the presence of anti-agglomerates was studied combined with the PVM and FBRM microscopic data analysis. The results indicated that the wax crystals would adsorb on the oil-water interfaces under the action of anti-agglomerates,reduce the reaction area of air-water nucleation and increase the mass transfer resistance of hydrate formation,thus inhibiting the formation and nucleation of hydrates leading to extension of the hydrate formation induction time and reduction of hydrate formation amount comparing with that in the wax free system. The aggregate formation coupling between the wax crystals and water droplets promoted the coalescence with hydrate particles,which increased the viscosity and decreased the fluidity of the hydrate slurry remarkably. The formation and flow of natural gas hydrate slurry with wax in the presence of anti-agglomerates was complex. And,the coupling mechanism between wax crystals and hydrates should be investigated further in the future,based on the existed independent research results of wax crystals and hydrates.