摘要
本文较系统地研究了海底沉积物的声学原位测试技术、原理与海洋沉积物声传播特性。研究内容包括声学原位测试系统的设计研制、海上资料采集、土工实验室测试、资料处理解释、中美不同性质沉积物的对比研究、Biot-Stoll模型与BISQ模型的海洋沉积物声学多参数反演,以及声场数值模拟。
本文在国家863计划的支持下,首次设计研制出国内具有自主知识产权的实时监控多频多深度声学原位测试系统,该系统既具有美国声学长矛测量深度较深的能力,又具有美国原位沉积物声学测量系统多个频率发射接收可研究频散特性的优点,系统具有实时监控甲板供电、多点高精度测量等特点。系统在整体设计思路上具有一定的先进性和创新性。
在浙江乍浦港首次取得了8、10、12和15kHz四个频率八个深度声学原位测试数据后,进行了土工力学和粒径分析。开发了利用对比法精确提取声速、声衰减技术。浙江乍浦港沉积物具有明显频散现象,即声速和声衰减随频率的增大而增大,声速随深度增加而增大(从1442到1462m/s)。得到了该海区2米深度内15kHz以下声速与深度及频率的一次正比关系。声衰减由于沉积物松软而较低。在沉积物中测到的声波主频比水中测得的主频低最高达300Hz。
对夏威夷檀香山岛的二处钙质沉积物20-100kHz的测量数据进行了原位纵波声速和声衰减提取。二处均测得轻微的频散。随频率的增加有效衰减从15增加到75 dB/m。声衰减较大。利用Blot-Stoll模型进行夏威夷钙质沉积物多参数反演,发现Biot理论能很好地描述珊瑚质砂纵波速度频散。通过调整低频耗散系数(超过Stoll的假设范围)对声衰减也能较好地描述。
得到海洋沉积物BISQ多参数反演方法。通过对浙江乍浦泥沙质沉积物的BISQ多参数反演,发现BISQ模型可用于描述海洋沉积物的声频散和声衰减特性。
海洋沉积物声衰减总体上分段符合衰减系数lnα=αlnf~b的规律。按斜率可以分成三段:f为高频时,b≈1;中频时,0≤b≤0.5;低频时b≈2。高频与中频分界在40kHz之间,中频与低频分界在16-18kHz之间。系数α与沉积物特性密切相关。
利用基于Biot理论模型的高阶交错网格有限差分算法,通过对比模拟和原位测试波形特征,表明该系统具有较好的首波避干扰和吸声设计,对下一步系统升级具有指导意义。
The in situ acoustic experimental technology, principle and propagation features inmarine sediments are described in this dissertation. This research includes the designand developing of the new in situ acoustic instrument, the experiment, engineeringanalysis, data processing, comparison of the different acoustic properties of USA andChinese sediments, multi-parameters inversion of Biot-Stoll model and BISQ model,and the finite-difference modeling.
Supported by 863 project, a real time control, multi-frequency and multi-depth in situacoustic system was developed with intellectual asset in the form of copyright. It hasreal time monitoring and on deck power supply, multi-point high resolutionmeasurement functions.
With four frequencies, which are 8, 10, 12 and 15 kHz, in situ acoustic data have beenacquired in 8 different depths at Zhapu bay, Zhejiang, China. By using antitheses, newtechnology of getting velocity and attenuation was used. Velocity dispersion in Zhapusediments is observed. The velocity and attenuation increase as the frequencyincreases. A linear relation between frequency and velocity as well as attenuation isfound while water depth less than 2 meters and frequency below 15 kHz. Thesediment is so soft that the attenuation is low. The dominate frequency in sediment is300Hz lower than that in water because of attenuation.
In situ compressional wave velocity and attenuation measurements were made at 2carbonate sediment sites over a frequency interval between 20 and 100 kHz. Velocitydispersion, while slight, appears in the data. Effective attenuation ranges from 15 to75 dB/m at H3 and from 22 to 62 dB/m at H4. Parameters determined by coreanalysis were fixed in Biot-Stoll models and inversion of velocity and attenuation datawas used to evaluate the 6 un-measurable parameters. An increase in the lowfrequency logarithmic decrement well above Stoll's recommended values allowed fitsto both velocity and attenuation very well.
The multi-parameter BISQ inversion method is achieved for Zhapu marine sediments.It is found that the BISQ model could be used to describe the marine sediment'scharacteristics of velocity dispersion and attenuation.
The lnα=alnf~b relationship for attenuation and frequency is approved in marinesediments. The slope b divides into three segments: b≈1 for higher frequency (f > 40kHz); 0≦ b≦0.5 for intermediate frequency (16-18 kHz); b≈2 for lower frequency(<16 kHz). The constant a depends on the characteristics of the sediments.
By comparing the high-order staggered finite-difference modeling based on the Biotmodel, with the in situ wave characteristics, it is indicated that the system is welldesigned in avoiding head wave inference and sound absorbing. This modeling hassignificance for upgrading the system.
引文
1.郭建,双相介质中P波波场的有限差分声波模拟,石油地球物理勘探,1992,27(2)
2.刘洋,牟永光,双向各向异性介质中弹性波的传播特征(摘要),中国地球物理年会会刊,西安地图出版社,1998
3.卢博,李赶先,黄韶健,海底沉积物声学的现场测量和取样系统,海洋技术,2000,19(3):31-33
4.刘银斌,李幼铭,横向各向异性多孔介质中的地震波传播,地球物理学报,1994,37(2)
5.门福禄,波在饱水孔隙介质中的传播,地球物理学报,1965,14(2)
6.牟永光等,储层地球物理学,石油工业出版社,1996
7.R.J.尤立克,水声原理,哈尔滨船舶工程学院出版社,1990
8.唐应吾,弹性波在沉积物中的传播,地球物理学报,1975,18(4)
9.陶春辉,Baffi S.,Wilkens R.H.,Fu S.S.,Richardson M.D.,金翔龙,Biot反演在Hawaii钙质沉积物原位测量声速与衰减中的应用,海洋学报,2005,(3)
10.陶春辉,金肖兵,金翔龙等,多频海底声学原位测试系统研制与应用,海洋学报,录用待刊
11.陶春辉、李家彪,海底物理与底质识别数字技术,S863海洋高新技术发展研讨会,2000(会议宣读)
12.田坦,刘国枝,孙大军,声纳技术,哈尔滨工程大学出版社,2000
13.王秀明,张海澜,王东.高阶交错网格有限差分算法模拟非均匀孔隙弹性介质中地震波的传播,地球物理学报,2003,46(6):842-849
14.吴家仁,张卫,海洋沉积物特性的现场测量方法,海洋技术,1984,3(1):69-77
15.杨顶辉,孔隙各向异性介质中基于BISQ模型的弹性波传播理论及有限元方法,博士后研究报告,石油大学(北京),1998
16.易良坤,席道瑛,刘斌,地震波的速度频散及衰减,中国地球物理学会年刊,1998
17.张卫,沉积物声速现场测量装置,声学技术,1984,3(3):25-30
18.周建平、吕文正、陶春辉,海底柱状沉积物超声测量,东海海洋,2003,21(4)
19.朱建伟,含流体空隙介质基于BISQ机制的弹性波波动方程及传播特性,长春科技大学博士学位论文,2000
20.Akbar,N.,Dvorkin,J.,and Nur,A.,Relating P-wave and attenuation to permeability:Geophysics,1993.,58:20-29
21.Barbagelata A.,Richardson M.D.,Miasehi B.,Muzi E.,Guerrini P.,Troiano L.,Akal T,ISSAMS:An In Situ Sediment Acoustic Measurement System,Shear Waves In Marine Sediments,1991
22.Batzle,M.,Han D,Fluids and frequency dependent seismic velocity of rocks.SEG 1999Expanded abstract,1999
23.Benson A.K.,Wu,J.,.A modelling solution for predicting(a) dry rock bulk modulus,rigidity modulus and(b) seismic velocities and reflection coefficients in porous,fluid-filled rocks with applications to laboratory rock samples and well logs,J.Appl.Geophy,1999,41:49-73
24.Blot M.A.,a,b.Theory of propagation of elastic waves in fluid saturated-porous solid,I.low frequency range,Ⅱ.High frequency range.J.Acoust.Soc.Am,1956,28:168-191
25.Biot,M.A.,General Theory of Three-Dimensional Consolidation:J.Appl.Phys,1941,12:155-164
26.Blot,M.A.,Mechanics of deformation and acoustic propagation in porous media:J.App.Phy.,1962a,33:1482-1498
27.Blot,M.A.,Generalized theory of acoustic wave propagation in porous dissipative media:J.Acoust.Soc.,Am.,1962b,34:1254-1264
28.Blatt,H.,Middleton,G.,and Murray,M.,Origin of Sedimentary Rocks,Prentice Hall,Englewood Cliffs,NJ,USA,1980,782
29.Bourbie,T.,Coussy O.,and Zinszner,B.,.Acoustics of porous media:Guif publishing,1987
30.Brown,R.J.S.,and Korringa,J.,On the dependence of the elastic properties of porous rock on the compressibility of pore fluid:Geophysics,1975,40:608-616
31.Buckingham M.J.,Richardson M.D.,On Tone-Burst Measurements of Sound Speed and Attenuation in Sandy Marine Sediments,IEEE Journal of Oceanic Engineering,July,2002,27(3):429-453
32.Buckingham,M.J.,Theory of acoustic attenuation,dispersion and pulse propagation in unconsolidated granular materials including marine sediments J.Acoust.Soc.Am.,1997,102,2579-2596
33.Chotiros N.P.,Smith E.,and Piper J.N,Refraction and Scattering Into a Sandy Ocean Sediment in the 30-40kHz Band,IEEE Journal of Oceanic Engineering,July,2002,27(3)
34.Chunhui Tao,Xianglong Jin,R.H.Wilkens,S.S.Fu,Multi-Frequency In Situ Sediment Geoacoustic Lance,EGU,2004
35.Domenico,S.N.,Effect of water saturation on seismic reflectivity of sand reservoir encased in shale:Geophysics,1974,39:759-769
36.Dvorkin,J.,and Nur,A.,Dynamic poroelasticity:A unified model with the squirt flow and the Biot mechanism:Geophysics,1993,58:524-533
37.Dvorkin,J.,MavkO,G.,and Nur.A.,Squirt flow ill fully saturated rocks:Geophysics,1995,60:97-107
38.Dvorkin,J.,Nolen-Hoeksema,R.,and Nur.A.,The Squirt flow mechanism:Macroscopic description:Geophysics,1995,59:428-438
39.Fan P.F.,Sediment of Kaneohe Bay,Oahu,Hawai'i,Consultant Reports,U.S.Army Corps of Engineers Appendix Ⅱ,1975
40.Frazer L.N.,Fu S.,Seabed sediment attenuation profiles from a movable sub-bottom acoustic vertical array,J.Acoust.Soc.Am.July 1999,106(1):120-130
41.Fu S.S.,Wilkens R.H.,Frazer L.N.,Hamilton's Parameters and the Acoustic Properties of Coral Sands,Walkiki,Hawai'i,Journal of the Acoustic Society of America,1999
42.Fu,S.S.,Wilkens,R.H.and Frazer,L.N.,A Acoustic Lance:New In Situ Seafloor Velocity Profiles,Journal of Acoustical Society of America,1996,99(1):234-242
43.Fu,S.S.,Wilkens,R.H.and Frazer,L.N.,A In Situ Velocity Profiles in Gassy Sediments:Kiel Bay,Geo-Marine Letters,1996,16:294-253
44.Fu,S.S.,The Experimental Study of In Situ Acoustic Properties in Marine Sediments,Ph.D.Dissertation,Department of Geology and Geophysics,University of Hawaii at Manoa,1998
45.Geli,L.,Pierre-Yves B.,and Schmitt,D.P.,Seismic propagation in a very permeable water-saturated surface layer:J.Geophys.Res.,1987,92:7931-7944
46. Gentilman R. L., Fiore D. F., Path H. T., French K. W., Bowen L. J., Fabrication and Properties of 1-3 PZT Polymer Composites, Ceramic Transactions 43, 1994
47. Gist, G. A., Fluid effects on velocity and attenuation in sandstones: J. Acoust. Am, 1994, 96: 1158-1173
48. Hamilton E. L., Sound Velocity gradients in marine sediments. Journal of the Acoustic Society of America, 1979,65(4)
49. Hamilton E. L., Geoacoustic Modeling of the Seafloor, Journal of the Acoustic Society of America, 1980, 68
50. Hassanzadeb, S., Acoustic modelling in fluid-saturated porous media: Geophysics, 1991, 56(4): 424-435
51. Hovwen, J. M., and Ingram G. D., Viscous attenuation of sound in saturated sand: J. Acoust. Soc. Am., 1979,66: 1807-1812
52. http://www.geotek.co.uk
53. Johnson, D. L. and Dashen, R. Theory of dynamic permeability and tortuosity in fluid saturated porous media: J. Fluid Mech., 1987, 176: 379-402
54. Johnson, D. L., Plona, T. J., Scala C., Pasierb, F., and Kojima, H., Tortuosity and acoustic waves: Phys. Rev. Lett., 1982,49: 1840-1844
55. Jones, M. S., McCann, C., Astin, T. R., and Sothcott, J., The effect of pore-fluid salinity on ultrasonic wave propagation in sandstones: Geophysics, 1998, 63: 928-934
56. Jones, T. D. Pore fluids and frequency-dependent wave propagation in rocks: Geophysics, 1986,51: 1939-1953
57. Klimentos, T., and MacCann C., Relationships among compressional wave attenuation, porosity, clay content, and permeability in sandstones: Geophysics, 1990, 55: 998-1014
58. Mamadou S. D., Acoustic waves attenuation and velocity dispersion in fluid-filled porous media: theoretical and experimental investigations, Ph.D. Dissertation, University Tubingen, 2000
59. Mavko, G. M., and Jizba, D., Estimating grain-scale fluid effects on velocity dispersion in rocks: Geophysics, 1991, 56: 1940-1949
60. Mavko, G.M. and Nur, A. Wave attenuation in partially saturated rocks: Geophysics, 1979, 44: 161-178
61. McCann C., and MeCann, D. M., A theory of compressional wave attenuation in noncohesive sediments: Geophysics, 1985,50: 1311-1317
62. Mukerji T., Mavko, G., Pore fluid effects on seismic velocity in anisotropic rocks. Geophysics, 1994, 59: 233-244
63. Murphy III. W. F, Winkler, K. W., and R. B. Kleinberg, Acoustic relaxation in sedimentary rocks: Dependence on grain contacts and fluid saturation: Geophysics, 1986, 51: 757-766
64. Nicholas P. Chotiros, A broadband model of sandy ocean sediments: Biot-Stoll with contact squirt flow and shear drag,J. Acoust. Soc. Am, 2004,116 (4): 2011-2022
65. Nicholas. P. Chotiros, An inversion for Biot parameters in water-saturated sand, J. Acoust. Soc. Am. 2002, 112(5): 1853-1868
66. O'Connell, R.J. and Budiansky, B., Viscoelastic properties of fluid-saturated cracked solids: J. Geophys. Res., 1977, 82: 5719-5736
67. Ogushwitz, P. R., Applicability of the Biot theory: II. Suspensions: J. Acoust. Soc. Am., 1985, 77: 440-452
68. Ogushwitz, P. R., Applicability of the Blot theory: III. Wave speeds versus depth in marine sediments: J. Acoust. Soc. Am., 1985, 77: 453-464
69. Palmer, I.D., Traviolia, M.L. Attenuation by squirt flow in undersaturated gas sands: Geophysics, 1981,45: 1780-1792
70. Plona, T. J., Observation of a second bulk compression wave in a porous medium at ultrasonic frequencies: Appl. Phys. Lett., 1980, 36: 259-261
71. Richardson M. D., Implications for High Frequency Acoustic Propagation and Scattering, Geo-Marine Letters, 1986
72. Richardson M D., On the Use of acoustic Impedance Values to Determine Sediment Properties, Proc. I. O. A. 1993, 15(2)
73. Shung Sheng Fu, Chunhui Tao, Manika Prasad, Roy H. Wilkens and L. Neil Fraser , Acoustic properties of coral sands, Waikiki, Hawaii. J. Acoust. Soc. Am. 2004, 115(4)
74. Stoll R. D, Comments on 'Biot model of sound propagation in water saturated sand'[J. Acoust. Soc. Am., 97,199-214(1995)], J. Acoust. Soc. Am., 1998,103(5)
75. Stoll R. D., Acoustic Waves in Ocean Sediments, Geophysics, 1977, 42
76. Stoll R. D., Marine Sediment Acoustics, Journal of the Acoustic Society of America, 1985, 77
77. Stoll R. D., Sediment Acoustic, Lectures Notes in Earth Science, 1989,26
78. Stoll R. D., Bryan G. Wave attenuation in saturated sediments. J. Acoust. Soc. Am, 1970; 47:1440-1447
79. Stoll R. D., Bryan G., Wave Attenuation in Saturated Sediments, Journal of the Acoustic Society of America, 1970, 47
80. Turgut, A. and Yamamoto, T., Synthetic seismograms for marine sediments and determination of porosity and permeability: Geophysics, 1988, 53: 1056-1067
81. Wang X. Seismic wave simulation in anisotropic media with heterogeneity using high-order finite-difference method. Proceedings of the 5* SEGJ international Symposium: imaging technology, Tokyo, Japan, 2001,113-120
82. Wang, Z., Nur, A., 1990. Dispersion analysis of acoustic velocities in rocks J. Acoust. Soc. Am., 87: 2384-2396
83. White, J.E., Underground sound: Application of seismic waves, Elsevier, Amsterdam, 1983
84. Wilkens, R. H., Richardson, R. D., The influence of gas bubbles on sediment acoustic properties: in situ, laboratory, and theoretical results from Eckernforde Bay, Baltic Sea, Continental Shelf Research 1998,18:1859-1892
85. Williams K. L., Jackson D. R., Thorsos E. I., Tang D, and Briggs K. B., Acoustic Backscattering Experiments in a Well Characterized Sand Sediment: Data/Model Comparisons Using Sediment Fluid and Biot Models, IEEE Journal of Oceanic Engineering, 2002, 27(3)
86. Williams K. L., Jackson D. R., Thorsos E. I., Tang D., Comparison of Sound Speed and Attenuation Measured in a Sandy Sediment to Predictions Based on the Biot Theory of Porous Media, IEEE Journal of Oceanic Engineering, 2002, 27(3), 413-428
87. Wingham D. J., the Dispersion of Sound in Sediment, J. Acoust. Soc. Am., 1985, 78(5)
88. Wulff, A. M., and Burkhardt H., Mechanisms affecting ultrasonic wave propagation in fluid-containing sandstones under high hydrostatic pressure: J. Geophy. Res. 1997,102(2): 3043-3050
89.Yamamoto,T.and Turgut,A.,Acoustic wave propagation through porous media with arbitrary pore size distributions:J.Acoust.Soc.Am.,1988,83:1744-1751
90.Yamamoto,T.,Nye,T.,and Kuru,M.,Porosity,permeability,shear strength:Crosswell tomography below an Iron foundry:Geophysics,1994,59:1530-1541