电阻率测试技术在沉积物-盐水-甲烷水合物体系中的应用

Application of Resistivity Measurement in the System of Sediment-Brine-Methane Hydrate

利用自制的一维天然气水合物(NGH)开采模拟实验系统,通过对NGH生成过程中电阻率、温度、压力等的变化规律进行分析,验证了在海洋沉积物体系中用电阻率法测试NGH的可行性。实验结果表明,电阻率可以清楚地反映NGH的成核及生长过程。NGH开始成核时消耗了溶液中的水分和甲烷气体,增加了离子之间的连通性,使电阻率降低;晶核开始生长为NGH后,由于生成的NGH类似于绝缘体,并且使得孔隙连通性变差,电阻率逐步升高,NGH大量生成后电阻率保持稳定。然后进行NGH降压分解实验,随着NGH的分解,NGH饱和度下降,电阻率也逐渐下降。

Using home-made one-dimensional experiment system of natural gas hydrate（NGH）,the feasibility of the resistivity measurement technique in the sediment-brine-methane hydrate system was validated by analyzing the change of resistivity,pressure and temperature during the process of the NGH formation.Results show that the nucleation and nucleus growth during NGH formation can be clearly observed from the resistivity change.When NGH begins to nucleate,the resistivity decreases due to the consumption of water and gas molecules,which results in ions connectivity increasing.When the nucleuses grow into NGH,the resistivity increases due to the NGH acts as an insulator,which decreases the ions connectivity.The resistivity becomes stable after the formation of mass NGH.Then the NGH dissociation experiment was performed by depressurization,the resistivity decreases gradually along with the dissociation of NGH.