热脉冲探针-时域反射技术测量含水合物沉积物的热导率及水合物饱和度

Measurement of Thermal Conductivity and Saturation of Gas Hydrates in Sediment by Thermal Pulse Probe-Time Domain Reflection Technique

我国在海洋和冻土区都已发现天然气水合物资源区并成功获取实物样品。含水合物沉积物的热导率是估算水合物资源量、设计合理开采方案的关键性数据之一。受水合物稳定条件和测量技术的限制,水合物热导率测定尚不完善。本文通过自主研制的天然气水合物热物理参数测量系统,开展了海洋沉积物中天然气水合物热导率与饱和度测量研究。实验使用取自南海神狐海域的沉积物作为反应介质,在压力7.8 MPa、温度2℃的条件下合成甲烷水合物,并利用热脉冲探针与时域反射技术联合测量的方式获得沉积物中水合物形成过程的热导率和饱和度等实验数据。结果表明,当水合物饱和度从0增加至49%时,体系热导率出现了先升高后降低的变化趋势。分析发现体系热导率随水合物饱和度的变化特征与水合物在沉积物中的填充方式有关,在实验选用的南海沉积物中,水合物优先选择在颗粒孔隙间成核生长,并最终与沉积物颗粒胶结共存。

So far, gas hydrates not only have been explored in marine and frozen areas of China, but also have been sampled successfully. The thermal conductivity of sediments with gas hydrates is a key parameter for estimating the resource and designing a proper exploitation plan. Restricted to the stable conditions for hydrates and their measurement technique, much more work need to be done on the thermal conductivity investigation of hydrates. In this paper, a description of the measurement technique of the thermal conductivity and saturation of gas hydrates formed in marine sediment is given. Marine sediment collected from the Shenhu area of the South China Sea was taken as the porous media. The methane hydrates in them were synthesized under the conditions of 7.8 MPa pressure and 2~C temperature. The thermal conductivity and saturation were measured by thermal pulse probe technique coupled with time domain reflection method. Based on the results, when the hydrate saturation changed from 0 to 49% , the thermal conductivity appeared to be initially increase and then decrease. It was deduced that the relationship between thermal conductivity and saturation was controlled by the hydrate filling pattern. In this experiment, gas hydrates priority selection in particle void nucleation and growth, and gradually cement with sediments.