基于探地雷达的实验室水合物物理模型制备与电磁特性研究

Preparation of laboratory hydrate physical model and research on the electromagnetic properties based on the ground penetrating radar

探地雷达是探测水合物的一项有效技术手段。通过模拟试验研究实验室水合物电磁特性与水合物饱和度等因素的关系,对陆域冻土区水合物勘探及储量估算具有重要的意义。通过实验室制样获得以均匀天然石英砂颗粒为骨架的含四氢呋喃水合物土样并对其介电常数进行研究,发现在1.5G高频雷达测试下,纯冰模型与四氢呋喃水合物具有明显的电磁特性差异;当四氢呋喃水合物模型饱和度大于35%时,水合物模型介电常数随水合物体积增大而增大,雷达波在模型中传播速度逐渐减小;四氢呋喃水合物在10℃室温及常压下可以保持近1 h的模型稳定性,当模型孔隙中水合物和液态四氢呋喃共存时,合成试样的四氢呋喃体积分数越大,孔隙中液态四氢呋喃越多,水合物模型的介电常数也随之增大。

Ground penetrating radar is an effective technology for detecting hydrates. Simulation test and study of the relationship be-tween electromagnetic characteristics and gas hydrate saturation as well as other factors show that ground penetrating radar has great sig-nificance for permafrost hydrate exploration and reserye estimation in terrestrial area. Through production of samples by the laboratory the authors obtained a uniform natural quartz sand particle as a skeleton containing tetrahydrofuran hydrate and studied its dielectric- constant. After the 1.5G high-frequency radar testing, it was found that the electromagnetic characteristics have obvious difference be-tween the pure hydrate model and the THF hydrate model. When the saturation of the model of tetrahydrofuran hydrate is higher than 35%, the volume of hydrate increases, the dielectric constant of hydrate model increases too, and the radar speed decreases in the model. The THF hydrate does keep stability in nearly one hour at 10 ^ room temperature and atmospheric pressure; when the hydrate and liquid tetrahydrofuran coexist in the pore of the model, the more the volume fraction of THF and the more liquid THF in the pore, the greater the dielectric constant of hydrate model is.