陆地天然气水合物孔底冷冻取样方法

如何获得品质优良的原状样品成为探明陆地天然气水合物赋存条件与储量的关键技术之一。在分析天然气水合物热物理性质和温压特性的基础上，采用主动式降温的方法，通过外部冷源在孔底降低水合物岩心温度，降低水合物的临界分解压力，抑制水合物分解，获得水合物保真样品：据此提出了天然气水合物孔底冷冻取样方法。设计的取样器总体结构由单动机构、控制机构和制冷机构组成，其工作原理主要为孔底冷冻岩心和地表取心，同时分析计算了取样器冷冻岩心所需的能量。通过钻探取样试验钻获冷冻岩心，证明天然气水合物孔底冷冻取样方法能够实现孔底冷冻岩样。该方法可以应用于天然气水合物保真取样。

Sampling for Land Gas Hydrates by Hole Bottom Freezing

In-situ sampling techniques are crucial to keep hydrate samples intact for characterizing the occurrence conditions and reserves of the gas hydrates in permafrost land.Having taken into account the thermophysical characteristic and the temperature-pressure dependence of gas hydrates,we have developed a borehole bottom freezing technique for gas hydrate sampling.This technique can significantly reduce the required sampling pressure and prevent decomposition of the hydrate samples by means of an external cold...