生物胶对二氧化碳水合物生成动力学影响实验研究

Experimental study of influence of biological gums on formation kinetics of carbon dioxide hydrates

天然气水合物的生成和沉积是深水钻、完井和油气输送过程中不可避免的挑战之一,同时在酸性天然气藏开发过程中,高浓度二氧化碳和硫化氢可使水合物更容易生成,造成水合物堵塞。高效经济、绿色环保的水合物抑制剂具有广阔的应用前景,是业内的研究热点。采用恒温恒容法研究了3种生物胶(黄原胶、瓜尔豆胶及卡拉胶)在不同质量分数、搅拌状态及与动力学抑制剂复配条件下对二氧化碳水合物生成动力学的影响。结果表明,黄原胶与瓜尔豆胶均具有抑制二氧化碳水合物生长的作用,其中黄原胶主要降低二氧化碳水合物的最终生成量,抑制效果更为明显,并且随着质量分数的增加,其动力学抑制效果增强。在静止状态下液体表面生成一层水合物膜,阻止气液接触,水合物生成量较少;搅拌桨对水合物膜的破坏作用使搅拌状态下的水合物生长速率远高于静止状态。分析实验结果后认为,黄原胶自身黏性增加了水合物颗粒的黏聚力,促进水合物固结成块,进而阻碍二氧化碳气体分子的传质过程,最终阻止水合物的进一步生成。研究结果对解决深水油气资源开发过程中水合物冰堵问题和开发绿色动力学水合物抑制剂具有理论指导意义。

The formation and deposition of natural gas hydrates are one of the inevitable challenges in deep-water drilling,completion and oil/gas transportation.And during the development of sour natural gas reservoirs,high concentrations of carbon dioxide and hydrogen sulfide make hydrates formation easier and cause hydrates blockage.High-efficiency,economical and environmentally friendly hydrate inhibitors have broad application prospects and are the research hotspot in the industry.The effects of three biological gums(xanthan gum,guar gum and carrageenan)on the formation kinetics of carbon dioxide hydrates were studied by adopting an isothermal and isochoric method under different mass fractions,stirring conditions and mixing with kinetic inhibitors.The results show that xanthan gum and guar gum have inhibition effect on the growth of carbon dioxide hydrates.Xanthan gum mainly reduces the ultimate amount of the formed hydrates and the inhibition effect is more obvious.Moreover,with the increases of mass fraction,the kinetic inhibition effect is enhanced.A hydrate layer can form at the surface of the solution under static condition and the amount of the formed hydrate is little.Due to the destructive effect of the stirrer on the hydrate layer,the growth rate of hydrates under stirring condition is much higher than that under static condition.It is supposed that the viscosity of xanthan gum increases the cohesion forces between the hydrate particles and promotes the aggregation of the hydrates into blocks,thereby hindering the mass transfer process of carbon dioxide gas molecules,further preventing the growth of the hydrates.The results of this study have theoretical significance to solve the hydrate ice blocking problem in the development of deepwater oil and gas resources and to develop green kinetic hydrate inhibitors.