中文摘要：

水合物在沉积物中生成和分解的定量和表征对于含水合物沉积物的物理性质的研究有重要意义。基于核磁共振（NMR）技术研究了水合物在砂中的形成和分解行为，以一种简便的方式计量了孔隙空间中各组分的含量，包括气体、液态水和水合物，并确定了水合数。在水合物形成和分解过程中试样的弛豫行为并没有发生突变，此外，对于含或不含水合物的试样，平均对数T2时间都与含水量成比例关系，直接的解释是液态水始终保持与颗粒表面的接触，弛豫主要发生在颗粒表面，表明水合物以孔隙填充或胶结的形式而不是颗粒涂层的方式存在。

英文摘要：

Quantification and characterization of hydrate formation and dissociation in sediments are highly important in the study of the physical properties of hydrate-bearing sediments. In this paper, the behavior of CO2 hydrate formation and dissociation in sand is studied using the nuclear magnetic resonance （NMR） technique. The components of the pore space, including gas, liquid water, and hydrate, were quantified using a convenient method by which the hydration number was determined. No abrupt change in the relaxation behavior of the sample was found during hydrate formation and dissociation. In addition, the value of mean-log T2 appeared to be proportional to the liquid water content of the sample with or without the pore hydrate. A straightforward explanation is that the liquid water in the pore space remains in contact with grain surfaces, and relaxation occurs mainly at the grain surface. The results suggest that, rather than coating the grains, the hydrate is pore-filling or cementing.