Effects of Anisotropic Features of Polar Anisotropic Media on Full Waveform Acoustic Logging

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2008 Vol.45, Issue 6 Preview Page Next Page

Effects of Anisotropic Features of Polar Anisotropic Media on Full Waveform Acoustic Logging 극이방성 매질의 이방성 특성이 전파형음파검층에 미치는 영향: 변중무
Joongmoo Byun

31 December 2008. pp. 635-648

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Abstract

Numerical experiments on the responses of full waveform acoustic logging in multi-layered anisotropic medium were performed with different anisotropic parameters and the results were analyzed. For the source of the logging tool, monopole and dipole source, which are mainly used in domestic logging survey, were considered. The responses of full waveform acoustic logging were calculated by discrete wavenumber method, and features of the responses were examined with changing the values of anisotropy parameters, ε, , and δ. In the case of the monopole source, the changes in anisotropy parameters have an effect on only the dispersion curve of Stoneley wave, not the velocities of P and S waves refracted at the borehole wall. The dispersion curve of Stoneley wave is most influenced by an anisotropy parameter, . For a dipole-source tool, the changes in the values of anisotropy parameters affect the dispersion curve of flexural wave similarly to the case of the monopole-source tool. However, for all cases, flexural wave propagates with the S wave velocity of the medium around the cut-off frequency.

Keywords

Full waveform acoustic logging

Anisotropy medium

Anisotropy parameter

Stoneley wave

Flexural wave

현재 국내에서 주로 사용되고 있는 단극자 송신원 음파검층기와 쌍극자 송신원 음파검층기를 이용하여 층서구조에 의한 이방성 매질 내에서 전파형음파검층을 수행할 경우 이방성 매질의 이방성 특성에 따른 검층 반응에서 나타나는 특징에 대해 수치모형 실험을 실시하였고, 그 결과를 분석하였다. 전파형음파검층 반응은 이산파수법을 이용하여 계산되었으며 매질의 이방성 특성을 결정하는 변수들인 ε, , δ 값들을 변화시켜가며 이에 따른 반응 특성에 대해 관찰하였다. 단극자 송신원을 이용하는 경우 이방성 변수들의 값들이 변함에 따라 시추공벽에서 굴절되어 수신기에 도달하는 P파나 S파의 속도에는 변화가 없었으며 단지 스톤리파의 분산곡선이 달라졌다. 이 때 스톤리파의 분산곡선은 이방성 변수 값의 변화에 제일 민감하게 반응하였다. 쌍극자 송신원을 이용한 음파검층의 경우에는 단극자 송신원의 경우와 유사하게 굽힘파의 분산곡선에 영향을 미쳤으나 어떠한 경우에도 굽힘파는 cut-off 주파수 부근에서는 매질의 S파의 속도를 가짐을 관찰할 수 있었다.

키워드

전파형음파검층

이방성 매질

이방성 변수

스톤리파

굽힘파

References

황세호, 이상규, 1999, “물리검층에 의한 파쇄대 인식과 동적 지반정수의 산출,” 한국물리탐사학회 특별심포지움, pp. 156-175.
Chan, A.K. and Tsang, L., 1983, “Propagation of acoustic waves in a fluid-filled borehole surrounded by a concentrically layered transversely isotropic formation,” 53rd Ann. Internat. Mtg. Soc. of Expl. Geophys, pp. 10-13.
Cheng, C.H. and Toksöz, M.N., 1981, “Elastic wave propagation in a fluid-filled borehole and synthetic acoustic logs,” Geophysics, Vol. 46, pp. 1042-1053.
Esmersoy, C., Koster, K., Williams, M., Boyd, A., and Kane, M., 1994, “Dipole shear anisotropy logging,” 64th Ann. Internat. Mtg. Soc. of Expl. Geophys, pp. 1139-1142.
Godinho, L. and Tadeu, A., 2002, “The importance of a small wall deformation in the three-dimensional acoustic logging results,” Geophys. J. Int., Vol. 151, pp. 403-415.
Huang, X., 2003, Effects of tool positions on borehole acoustic measurements: a stretched grid finite difference approach, Ph.D. Thesis, Massachusetts Institute of Technology, USA.
Kurkjian, A.L. and Chang, S., 1986, “Acoustic multipole sources in fluid-filled boreholes,” Geophysics, Vol. 51, pp. 148-163.
Nolte, B., Rao, R., Huang, X., 1997, “Dispersion analysis of split flexural waves,” M.I.T. Borehole Acoustics and Logging and Reservoir Delineation Consortia Annual Report, 12-1-12-25.
Paillet, F.L. and Cheng, C.H., 1991, Acoustic waves in boreholes, CRC press.
Schmitt, D.P., 1988a, “Transversely isotropic saturated porous formations: I. Theoretical developments and (quasi) body wave properties,” M.I.T. Borehole Acoustics and Logging and Reservoir Delineation Consortia Annual Report, pp. 247-308.
Schmitt, D.P., 1988b, “Transversely isotropic saturated porous formations: II. Wave propagation and application to multipole logging,” M.I.T. Borehole Acoustics and Logging and Reservoir Delineation Consortia Annual Report, pp. 309-462.
Schmitt, D., 1993, “Dipole logging in cased boreholes,” J. Acoust. Soc. Am., Vol. 93, pp. 640-657.
Tadeu, A., Godinho, L., and Santos, P., 2002, “Wave motion between two fluid-filled boreholes in an elastic medium,” Engineering Analysis with boundary Elements, Vol. 26, pp. 101-117.
Thomsen, L., 1986, “Weak elastic anisotropy,” Geophysics, Vol. 51, No. 10, pp. 1954-1966.
Thomsen, L., 2002, “Understanding seismic anisotropy in exploration and exploitation,” 2002 Distinguished instructor short course, Society of Exploration Geophysicists.
Tubman, K.M., Cheng, C.H., and Toksöz, M.N., 1984, “Synthetic full waveform acoustic logs in a cased boreholes,” Geophysics, Vol. 49, pp. 1051-1059.
White, J.E. and Tongtaow, C., 1981, “Cylindrical waves in transversely isotropic media,” J. Acoust. Soc. Am., Vol. 70, pp. 1147-1155.

Information

Publisher :The Korean Society of Mineral and Energy Resources Engineers
Publisher(Ko) :한국자원공학회
Journal Title :Journal of the Korean Society for Geosystem Engineering
Journal Title(Ko) :한국지구시스템공학회지
Volume : 45
No :6
Pages :635-648

[1] 황세호, 이상규, 1999, “물리검층에 의한 파쇄대 인식과 동적 지반정수의 산출,” 한국물리탐사학회 특별심포지움, pp. 156-175.

[2] Chan, A.K. and Tsang, L., 1983, “Propagation of acoustic waves in a fluid-filled borehole surrounded by a concentrically layered transversely isotropic formation,” 53rd Ann. Internat. Mtg. Soc. of Expl. Geophys, pp. 10-13.

[3] Cheng, C.H. and Toksöz, M.N., 1981, “Elastic wave propagation in a fluid-filled borehole and synthetic acoustic logs,” Geophysics, Vol. 46, pp. 1042-1053.

[4] Esmersoy, C., Koster, K., Williams, M., Boyd, A., and Kane, M., 1994, “Dipole shear anisotropy logging,” 64th Ann. Internat. Mtg. Soc. of Expl. Geophys, pp. 1139-1142.

[5] Godinho, L. and Tadeu, A., 2002, “The importance of a small wall deformation in the three-dimensional acoustic logging results,” Geophys. J. Int., Vol. 151, pp. 403-415.

[6] Huang, X., 2003, Effects of tool positions on borehole acoustic measurements: a stretched grid finite difference approach, Ph.D. Thesis, Massachusetts Institute of Technology, USA.

[7] Kurkjian, A.L. and Chang, S., 1986, “Acoustic multipole sources in fluid-filled boreholes,” Geophysics, Vol. 51, pp. 148-163.

[8] Nolte, B., Rao, R., Huang, X., 1997, “Dispersion analysis of split flexural waves,” M.I.T. Borehole Acoustics and Logging and Reservoir Delineation Consortia Annual Report, 12-1-12-25.

[9] Paillet, F.L. and Cheng, C.H., 1991, Acoustic waves in boreholes, CRC press.

[10] Schmitt, D.P., 1988a, “Transversely isotropic saturated porous formations: I. Theoretical developments and (quasi) body wave properties,” M.I.T. Borehole Acoustics and Logging and Reservoir Delineation Consortia Annual Report, pp. 247-308.

[11] Schmitt, D.P., 1988b, “Transversely isotropic saturated porous formations: II. Wave propagation and application to multipole logging,” M.I.T. Borehole Acoustics and Logging and Reservoir Delineation Consortia Annual Report, pp. 309-462.

[12] Schmitt, D., 1993, “Dipole logging in cased boreholes,” J. Acoust. Soc. Am., Vol. 93, pp. 640-657.

[13] Tadeu, A., Godinho, L., and Santos, P., 2002, “Wave motion between two fluid-filled boreholes in an elastic medium,” Engineering Analysis with boundary Elements, Vol. 26, pp. 101-117.

[14] Thomsen, L., 1986, “Weak elastic anisotropy,” Geophysics, Vol. 51, No. 10, pp. 1954-1966.

[15] Thomsen, L., 2002, “Understanding seismic anisotropy in exploration and exploitation,” 2002 Distinguished instructor short course, Society of Exploration Geophysicists.

[16] Tubman, K.M., Cheng, C.H., and Toksöz, M.N., 1984, “Synthetic full waveform acoustic logs in a cased boreholes,” Geophysics, Vol. 49, pp. 1051-1059.

[17] White, J.E. and Tongtaow, C., 1981, “Cylindrical waves in transversely isotropic media,” J. Acoust. Soc. Am., Vol. 70, pp. 1147-1155.

Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

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