井中震电效应的模拟实验研究(Ⅱ):孔隙饱和岩石部分
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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.
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.
引文
[1] 韩学辉,何亿成,楚泽涵,等.井中震电效应的模拟实验研究(Ⅰ):井液部分[J].地球物理学进展,2004,19(2):399～403.
[2] 楚泽涵.声波测井原理[M].北京:石油工业出版社,1987:44～58,75～79.
[3] O.A.波达波夫,等著.震电勘探原理[M].裘慰庭译.北京:石油工业出版社,997.
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[5] 赵玉林,钱复业,张德陪,等.地电台的最佳台址条件———岩石电阻率对应变的高放大系数及低的干扰幅度[A].见:地磁地电分册[C].北京:地震出版社,1988:170～179.
[6] 毛桐恩,席继楼,王燕琼,等.地震过程中的大地电场变化特征[J].地球物理学报,1999,42(4):520～528.
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[11] 刘祝萍,吴小薇,楚泽涵.岩石声学参数的实验测量及研究[J].地球物理学报,1994,37(5):87～92.
[12] 丁次乾.矿场地球物理[M].北京:石油工业出版社,1992.
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[2] 楚泽涵.声波测井原理[M].北京:石油工业出版社,1987:44～58,75～79.
[3] O.A.波达波夫,等著.震电勘探原理[M].裘慰庭译.北京:石油工业出版社,997.
[4] PointerT,LiuE,Hudson.Seismicwavepropagationincrackedporousmedia[J].GeophysJInt,2000,142:199～231.
[5] 赵玉林,钱复业,张德陪,等.地电台的最佳台址条件———岩石电阻率对应变的高放大系数及低的干扰幅度[A].见:地磁地电分册[C].北京:地震出版社,1988:170～179.
[6] 毛桐恩,席继楼,王燕琼,等.地震过程中的大地电场变化特征[J].地球物理学报,1999,42(4):520～528.
[7] 王玲,何继善.描述激电效应的非线性扩散方程[J].地球物理学报,1999,42(6):849～857.
[8] 刘洪,严洪瑞,等.电场地震资料的特征[A].见:寸丹集(庆祝刘光鼎院士工作50周年学术论文集)[C].北京:科学出版社,1998:145～153.
[9] 严洪瑞,刘洪,李幼铭等.震电勘探方法在大庆油田的实验研究[J].地球物理学报,1999,42(2):257～266.
[10] 李建勇,刘洪,李幼铭,等.大庆电场地震资料的面波特征[J].地球物理学进展,2001,16(4):29～34.
[11] 刘祝萍,吴小薇,楚泽涵.岩石声学参数的实验测量及研究[J].地球物理学报,1994,37(5):87～92.
[12] 丁次乾.矿场地球物理[M].北京:石油工业出版社,1992.
[13] T.布尔贝,O.库索,B.甄斯纳著[M].许云译.北京:石油工业出版社,1994.
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