含天然气水合物的海底沉积物的电学特性实验  

Resistivity measurement on the marine sediments containing natural gas hydrate

作　　者：陈玉凤[1,2,3] 李栋梁[1,2] 梁德青[1,2] 杜建伟[1,2,3] 吴能友[1,2] 

机构地区：[1]中国科学院广州能源研究所,中国科学院可再生能源与天然气水合物重点实验室,广州510640 [2]中国科学院广州能源研究所,天然气水合物中心,广州510640 [3]中国科学院研究生院,北京10049

出　　处：《地球物理学进展》2013年第2期1041-1047,共7页Progress in Geophysics

基　　金：国家973项目(2009cb219504)资助

摘　　要：电阻率法是估算含水合物储层饱和度的常用方法之一.为了解海底沉积物中天然气水合物的电学特性,利用搭建的天然气水合物电阻率测量系统,以天然气水合物-南海沉积物-3.5%的盐水为研究体系,测量了天然气水合物在沉积物中形成过程中温度、压力、电阻率的变化.天然气水合物在水饱和的沉积物中由溶解气与水形成.实验中通过液压系统对沉积物压实以及采用较薄的样品来保证水合物在筒状的沉积物的均匀分布.当实验结束时,样品中水合物的饱和度达到39.8%时,样品的电阻率从水饱和时的2.024Ωm增大到水合物饱和度为39.8%时的2.878Ωm,增加到了1.4倍.电阻率法可以有效的识别含水合物的沉积物.实验测试结果表明,该实验装置工作稳定可靠,可为研究含天然气水合物的电学特性与饱和度的定量关系提供实验模拟技术支持.Electrical resistivity log data can be commonly used to estimating gas hydrate saturation in ocean sediments. Unfortunately, the relations between resistivity and hydrate saturation are some uncertainty. To know about the electricity resistivity properties of marine sediments containing natural gas hydrate, an experimental device designed was used to measure and study the changes in temperature, pressure, and electricity resistivity in the formation processes of natural hydrate gas within the marine sediments. Methane dissolved in 3. 5 % sodium chloride solution and water formed the pore space hydrate in the fully water saturated sediments. A lateral load provided by a hydraulic system waa used to compact the sediments and to ensure good contact between the samples and electrodes. Besides, some method was taken to obtain the homogeneity of gas hydrate distribution in the sediments. When the formation process ended, at 2. 3℃, the hydrate saturation which can be derived from the consumed gas volume was 39.8%. And the resistivity of sediment increased from 2. 024 tim at fully water saturation to 2. 878 tim at 39. 8% hydrate content, it increased nearly 1.4 orders of magnitude upon hydrate formation. The sediments have high electrical resistivity compared to sediments without gas hydrate. The method of electricity resistivity can be used to detect the process of hydrate formation in the marine sediment and the laboratory data can be provide to calibrate and interpret of geophysical measurements and electricity down-hole logs. The experimental results show that the experimental device was reliable, and it provides a technical support to understand the quantitative relationship between the resistivity of the gas hydrate-bearing sediments and hydrate saturation.

关 键 词：天然气水合物 电阻率 沉积物 饱和度 

分 类 号：P631[天文地球—地质矿产勘探]