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建立了利用X射线计算机断层成像(X-CT,X-ray computed tomography)研究天然气水合物在沉积物空隙中填充过程和赋存状况的测试系统。针对数据图像中水和水合物灰度相近不易区分的难题,采用提高密度差和添加标定物的方法对其进行改善。通过重建的二维和三维影像,可清晰地观察到自由气、沉积物、水和水合物的微观分布状态。在自行研制的可控温高压反应装置内合成CH4水合物,并对其生长过程进行了跟踪扫描。反应过程前后图像数据的对比表明,水合物最初主要在沉积物颗粒表面与气液界面处生长,随后逐渐占据大部分液相空间,最终连同所有的沉积物颗粒胶结在一起。实验结果证明,高精度X-CT应用于含水合物的沉积物样品内部结构测试以及水合物在沉积物空隙中的动力学机理研究是可行且有效的。
A test system for the filling process and occurrence of gas hydrate in sediment voids was established by using X-ray computed tomography (X-ray computed tomography). Aiming at the difficult problem that water and hydrate in the data image are similar and difficult to be distinguished, the method of improving the density difference and adding the calibrator is used to improve the problem. The microscopic distribution of free gas, sediment, water and hydrate is clearly visible through reconstructed 2D and 3D images. CH 4 hydrate was synthesized in a self-developed controlled-temperature and high-pressure reactor, and its growth was tracked. Comparisons of the image data before and after the reaction show that the hydrate initially grows primarily at the particle surface of the sediment and at the gas-liquid interface and then gradually occupies most of the liquid phase space and eventually binds with all the sediment particles. The experimental results show that it is feasible and effective to apply high-precision X-CT to the internal structure test of hydrate-bearing sediment samples and to study the kinetics of hydrate in sediment voids.