Micro-CT造影剂在多孔介质内水合物-水两相分辨中的应用评价

天然气水合物资源开采过程中涉及多孔介质内固(水合物)-液(水)-气(天然气)复杂相态转变及多相流体流动与热质传递,因此实现多相流体的相分辨是开展研究的关键问题之一。利用Micro-CT技术,以四氢呋喃水合物(THF)作为研究对象,开展了固(水合物)-液(水)两相分辨的造影剂效果评价研究。发现溶液内添加造影剂KI的分辨效果要远好于NaCl,KI的分辨效果随着质量分数的增加先增加后减小,最后处于较低值维持不变,KI质量分数为6%时分辨效果最好,可以实现多孔介质内小密度差的水与水合物相分辨及水合物分解过程相界面变化的动态可视化检测。基于此,利用阈值法可以进一步实现分解过程中水合物饱和度的定量分析,获取多相流动过程的各相流体原位和度变化数据。

Evaluation of Micro-CT contrast agent for hydrate-water two phase distinguishing in porous media

Complex solid (hydrate) - liquid (water) - gas (natural gas) phase transition and multiphase fluids flow and heat and mass transfer in porous media are involved in the exploitation of natural gas hydrate resources. Therefore, the phase distinguishing of multiphase fluids is one of the key issues. In this study, the Tetrahydrofuran (THF) hydrate was studied as the research object for the effect evaluation of contrast agent with solid (hydrate) - liquid (water) two phase distinguishing using Micro X-ray computed tomography (Micro-CT) technique. It was found the distinguishing effect of KI in solution was much better than that of NaCl. Besides, the distinguishing effect of KI increased first and then decreased with the increase of KI concentration, and then it remained unchanged at the lower value. When the KI concentration was 6%, the distinguishing effect was the best, which could be used to realize the small density difference between water and hydrate phase distinguishing in the porous media and the dynamic visual detection of phases interface changes during the hydrate decomposition process. The quantitative calculation hydrate saturation during the decomposition process could also be realized based on the threshold value method, the in-situ fluids saturation of each phase were acquired during the multiphase flow.