Biot反演在夏威夷钙质沉积物原位测量声速和衰减中的应用
Biot inversion for in-situ velocity and attenuation data A case study in Hawaii, USA
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摘要: 对夏威夷檀香山岛的两个站(H3和H4)钙质沉积物进行了20~100kHz的原位纵波声速和声衰减测量.它们均有轻微的频散.随频率的增加H3站位声速从1691m/s增加到1708m/s,H4站位的声速从1579m/s增加到1585m/s.随频率的增加H3站位的有效衰减从15dB/m增加到75dB/m,H4站位的有效衰减从22dB/m增加到62dB/m.运用Biot-Stoll模型对所测得的纵波速度和声衰减数据进行了Biot模型未知参数反演,发现粒径较大的H3站的沉积物(孔隙率为45%)比粒径较小的H4站的沉积物(孔隙率为56%)具有曲率小和渗透率及孔隙半径都大的性质.Abstract: In situ compressional wave velocity and attenuation measurements were made at 2 carbonate sediment sites over a frequency interval between 20 and 100 kHz.Velocity dispersion,while slight,appears in the data.Velocities increase from 1691 to 1708 m/s at Site H3 and from 1579 to 1585 m/s at Site H4 as the frequency increased.Effective at tenuation ranges from 15 to 75 dB/m at Site H3 and from 22 to 62 dB/m at Site H4.Parameters determined by core analysis were fixed in Biot-Stoll models and inversion of velocity and at tenuation data was used to evaluate the 6 unmeasurable parameters.It is found that Site H3 (porosity is 44%) has lower tortuosity,higher permeability and average pore radius than Site H4 (porosity is 56%) after inversion.Good fits were achieved for both velocity datasets,but corresponding modeled attenuation is low.An increase in the low frequency logarithmic decrement well above Stoll's recommended values allowed fits to both velocity and attenuation very well.
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Key words:
- Biot inversion /
- in-situ measurement /
- velocity /
- attenuation
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