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针对现有天然气水合物保真取样技术的不足,提出了孔底冷冻保真取样技术.分析了孔底冷冻取样方法的几个特点,并基于干冰和液氮2种不同冷源的温压特性,分别对2种冷冻方式的天然气水合物孔底冷冻取样器进行了探讨.数值模拟了在孔深350 m处,钻取天然气水合物岩心并注入冷源后,在孔底冷冻岩心及提升岩心时岩心温度随时间变化的过程,并通过钻探取样试验获得冷冻岩心.结果表明:孔底冷冻取样方法可以实现在孔底冷冻岩心,满足天然气水合物保真取样的要求.
In order to solve the shortage of sampling technology of gas hydrate, a method of freezing and fidelity sampling at the bottom of the hole was proposed, and some characteristics of sampling method were analyzed. Based on the temperature and pressure characteristics of two kinds of cold sources , Two kinds of freezers for gas hydrate bottom hole freezing sampler were discussed respectively.Numerical simulation was made at the hole depth of 350 m after drilling the gas hydrate core and injecting the cold source to freeze the core and lift the core The core temperature changes with time, and the frozen core is obtained by drilling sampling test.The results show that the method of freezing sampling at the bottom of the hole can be used to freeze the core at the bottom of the hole to meet the requirement of gas hydrate fidelity sampling.