饱和砂岩滞弹性弛豫热激活过程机理探讨
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摘要
物理模型实验揭示：流体饱和度、孔隙流体的特性，地震波的频率和岩石孔隙的纵横向尺寸比对地震波的衰减都有很大的影响。本文借鉴滞弹性弛豫热激活过程的研究来描述地震波在饱和砂岩中的衰减机理。首先研究成分单一的长石砂岩在水、原油、油水混合液饱和条件下的弛豫特性，发现产生弛豫峰的王要原因是孔隙液体与长石砂岩孔隙界面上的相界弛豫。对于由初隙液体饱和的多孔岩石可以用普遍化的Voigt三参数模型和Cole－Cole分布描述。由于孔隙液体饱和的多孔岩石中普遍存在着多重弛豫的叠加，所以造成弛豫峰变宽。实验表明，油水混合液饱和砂岩的弛豫最宽，石油饱和砂岩比泵油饱和砂岩的分布宽度稍大，水饱和砂岩的弛豫峰较窄。
Physical model experiment reveals that fluid saturation, the characteristic offluid in pores, seismic wave frequency and the ratio of vertical size to lateral size ofa pore all cause great influence on seismic wave attenuation. With the aid of a research on heating activation of viscoelastic relaxation, we analyse how seismic waveattenuates in fluid saturated sandstone. Having analysed some relaxation characteristics of feldspathic sandstone plates which were saturated respectively by water,crude oil and oil-water mixture, we found that the main reason why relaxation peakexists is the phase boundary relaxation at interface between fluld and pore withinfeldspathic sandstone. Fluid-saturated porous rock can be described by using generalized Voigt three-parameter model and Cole-Cole distribution. The relaxation peakusually widens because there exists stack phenomenon of multiple relaxations influid-saturated porous rock. Experiment led to the conclusion: the relaxation peakof oil-water saturated sandstone is wide, the distribution width of crude-saturatedsandstone is little bigger than that of pump-oil saturated sandstone, and the relaxation peak of water-saturated sandstone is narrow.
Physical model experiment reveals that fluid saturation, the characteristic offluid in pores, seismic wave frequency and the ratio of vertical size to lateral size ofa pore all cause great influence on seismic wave attenuation. With the aid of a research on heating activation of viscoelastic relaxation, we analyse how seismic waveattenuates in fluid saturated sandstone. Having analysed some relaxation characteristics of feldspathic sandstone plates which were saturated respectively by water,crude oil and oil-water mixture, we found that the main reason why relaxation peakexists is the phase boundary relaxation at interface between fluld and pore withinfeldspathic sandstone. Fluid-saturated porous rock can be described by using generalized Voigt three-parameter model and Cole-Cole distribution. The relaxation peakusually widens because there exists stack phenomenon of multiple relaxations influid-saturated porous rock. Experiment led to the conclusion: the relaxation peakof oil-water saturated sandstone is wide, the distribution width of crude-saturatedsandstone is little bigger than that of pump-oil saturated sandstone, and the relaxation peak of water-saturated sandstone is narrow.
引文
1 Spencer J W.Stress relaxation at low frequence in fluid-saturated rock attenuation and modulus disper-sion.J Geophy,1981,Res,86:1803～1812
2 Johns T D.Pore fluids and frequency-dependent wave propagation in rocks.Geophysics,1986,51(10):1939～1953
3 Zhu Guozhen and Pan Yongdong.Acoustic relaxation of fluid-saturated porous sample.J Acoustic SocAm,1993,94(1):537～541
4 付承义,陈运泰,祁贵仲等著.地球物理学基础,科学出版社,1985
5 席道瑛,谭启,马延路.含水花岗岩的低频衰减峰.科学通报,1995,40(5):479～480
2 Johns T D.Pore fluids and frequency-dependent wave propagation in rocks.Geophysics,1986,51(10):1939～1953
3 Zhu Guozhen and Pan Yongdong.Acoustic relaxation of fluid-saturated porous sample.J Acoustic SocAm,1993,94(1):537～541
4 付承义,陈运泰,祁贵仲等著.地球物理学基础,科学出版社,1985
5 席道瑛,谭启,马延路.含水花岗岩的低频衰减峰.科学通报,1995,40(5):479～480
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