A method for coal structure division based on AVO simultaneous inversion
Wu, H., Dong, S., Huang, Y., Chen, G. and Wang, H., 2015. A method for coal structure division based on AVO simultaneous inversion.Journal of Seismic Exploration, 24: 365-378. Prospecting for enriched areas must be the primary goal of seismic exploration of coal-bed methane (CBM) reservoirs, and coal structure is the principal factor controlling CBM enrichment within a mining field that has relatively uniform geological characteristics such as reservoir thickness, cap rock, and coal quality. Based on reservoir rock physics and coal structure theory, this study found that development areas of mylonitized coal, which correspond to CBM-enriched areas, show abnormally low values of P-wave and S-wave impedance (Ip and Ix). It was also established that I, and I, act as valid parameters for coal structure division. Before adopting a pre-stack inversion for I, and Is, the applicability of the AVO approximation equation (expressed by lp and I,) with small incidence angles (< 30°) was tested and verified. Thereafter, the AVO inversion equation based on Bayes’ theorem could be derived by adopting the modified Cauchy distribution as the prior distribution. A test using a model typical of a CBM reservoir containing Gaussian white noise illustrated the stability of this inversion method and provided accurate inversion values for I, and I,. Moreover, the seismic profile of a CBM reservoir ina field in Qinshui Basin, as an inversion case study, revealed an area of abnormally low values of I, and I,. This demonstrated that the method is capable of the effective division of coal structure types in a CBM reservoir and of the delineation of areas of mylonitized coal development.
- Alemie, W., 2010. Regularization of the AVO inverse problem by means of a multivariate Cauchyprobability distribution. M.Sc. thesis, University of Alberta, Edmonton.
- Alemie, W. and Sacchi, M.D., 2011. High-resolution three-term AVO inversion by means of a
- Trivariate Cauchy probability distribution. Geophysics, 76(3): R43-R55.
- Buland, A. and Omre, H., 2003. Bayesian linearized AVO inversion. Geophysics, 68(1): 185-198.
- Chen, X.P., Huo, Q.M., Lin, J.D., Wang, Y., Sun, F.J., Li, W.Z. and Li, G.Z., 2013. Theinverse correlations between methane content and elastic parameters of coal-bed methanereservoirs. Geophysics, 78(4): D237-D248.
- Chen, X.P., Huo, Q.M., Lin, J.D., Wang, Y.. Sun, F.J., Li, W.Z. and Li, G.Z., 2014. Theoryof CBM AVO: 1. Characteristics of anomaly and why it is so. Geophysics, 79(2): D55-D65.
- Downton, J.E. and Lines, L.R., 2004. Three term AVO waveform inversion. Expanded Abstr., 74thAnn. Internat. SEG Mtg., Denver, 23: 215-218.
- Downton, J.E., 2005. Seismic parameter estimation from AVO inversion. Ph.D. thesis, Universityof Calgary, Calgary.
- Fatti, J.L., Smith, G.C., Vail, P.J., Strauss, P.J. and Levitt, P.R., 1994. Detection of gas insandstone reservoirs using avo analysis: A 3-D seismic case history using the Geostacktechnique. Geophysics, 59: 1362-1376.
- Fu, X.H., Qin. Y. and Wei, Z.T., 2007. Coal-bed Methane Geology. China University of Miningand Technology Press, Xuzhou.
- Li, J.J., Cui, R.F., Pan, D.M., Chen, S.E., Hu, M.S. and Zhao, X., 2013. Prediction of gasoutburst in a coalmine based on simultaneous prestack seismic inversion: a case study inChina. J. Seismic Explor., 22: 463-475.
- Ma, J.Q. and Geng, J.H., Cauchy prior distribution-based AVO elastic parameter estimation viaweakly nonlinear waveform inversion. Appl. Geophys., 2013, 10: 442-452.
- Peng, S.P., Gao, Y.F., Yang, R.Z., Chen, H.Q. and Chen, X.P., 2005. Theory and application of
- AVO for detection of coal-bed methane-A case from the Huainan coal-field. Chin. J.Geophys. (in Chinese), 48: 1475-1486.
- Peng, S.P., Chen, H.J., Yang, R.Z., Gao, Y.F. and Chen, X.P., 2006. Factors facilitating orlimiting the use of AVO for coal-bed methane. Geophysics, 71(4): C49-C56.
- Qi. X.M. and Zhang, S.C., 2012. Application of seismic multi-attribute fusion method based on D-Sevidence theory in prediction of CBM-enriched area. Appl. Geophys., 9: 80-86.
- Wang, X., 2012. Research on prediction method by seismic attributes for high-risk coal of coal andgas outburst. Ph.D. thesis, China Univ. of Mining and Technology, Qingdao.
- Zhang, F.Q., Wei, F.J., Wang, Y.C., Wang, W.J. and Li. Y., 2013. Generalized linear AVOinversion with the priori constraint of trivariate Cauchy distribution based on Zoeppritzequation. Chin. J. Geophys. (in Chinese), 56: 2098-2115.
- Zong, Z, Yin, X. and Wu, G., 2012. AVO inversion and poroelasticity with P- and S-wave moduli.Geophysics, 77(6): N17-N24
- Zong, Z., 2013. Methodologies of model driven inversion with pre-stack seismic data. Ph.D. thesis,China Univ. of Petroleum, Huadong.
