摘要
使用小功率直流电源(32V,3A),正交于声波传播方向供电,实验考察了直流电场对4块砂岩岩心的声学性质的影响,发现了一些以往文献没有报导的实验现象,总体上,有1)随通电时间增长,电流强度下降,最后趋于"饱和";2)岩石的声速有先降后升的趋势,相对变化一般小于2%;3)纵波幅度呈现下降趋势,相对变化幅度最大可达到80%;4)声速和声幅的变化与岩石的渗透率有正相关关系,例如D7#20由于渗透率很低,因此声速和声幅的变化很小.结合岩石电阻率增大以及对含水饱和度影响岩石声学性质的一般认识,认为实验现象与电解导致的岩石孔隙内部含水饱和度的下降有关.研究结果有助于丰富对目前电法 地震勘探实验某些现象的认识.
With the employment of low power DC electrical source(32V,2.5A), the DC is supplied vertically to the direction of acoustic propagation, the effect of DC on acoustic property of porous saturated media-rock was reviewed with 4 sand rocks. Some new phenomena are found, generally: 1) the current descends with the time and 'saturats' at last; 2) the velocity of P-wave initially, then ascends. The scope of variation of velocity of P-wave is lower than 2%; 3)the amplitude of P-wave shows a trend to descend, the scope of variation was about 80%;4) the variation of velocity and amplitude shows positive correlativity with the penetrability, for instance, rock D7#20 shows low variation because of its low penetrability. With the references of the increase of resistivity and the knowledge of relation between acoustic properties and saturation, the experimental phenomena are contributed to the decrease of water saturation in pore of rock triggered by electroanalysis. The result is helpful to enrich the knowledge on the phenomena occurred in the experimental study on seismo-electric.
出处
《地球物理学进展》
CSCD
2004年第3期641-644,共4页
Progress in Geophysics
关键词
震电效应
纵波幅度
渗透率
电阻率
含水饱和度
seismo-electric, P-wave's amplitude, penetriability, resistivity, water saturation
