Prediction of brittleness based on anisotropic rock physics model for kerogen-rich shale
Qian Ke-Ran1,2,3,4, He Zhi-Liang1,2,3,4, Chen Ye-Quan1,2,3,4, Liu Xi-Wu1,2,3,4, and Li Xiang-Yang5
This study is financially supported by the NSFC and Sinopec Joint Key Project (No. U1663207), National Science and Technology Major Project (No. 2017ZX05049-002), and National 973 Program (No. 2014CB239104).
摘要 岩石物理建模及脆性指数构建是影响脆性预测精度的两大重要环节。现有页岩模型对有机质的模拟争议较大，需要寻找合理的岩石物理理论来模拟富有机质页岩。同时，现有脆性公式种类繁多，各公式的适用性值得探究。本文利用Self-Consistent Approximation and the Differential Effective Medium（SCA+DEM）理论，通过模拟有机质与粘土的耦合性，构建各向异性富有机质岩石物理模型。与前人理论对比，初步验证了本模型的有效性；同时，基于模型构建脆性模板，分析物性参数对各脆性指数公式的影响。结果显示：各脆性公式对不同物性条件下地层的敏感性不同，基于杨氏模量构建的脆性指数对矿物含量的变化较敏感，而基于拉梅系数构建的脆性公式对孔隙度/孔隙流体敏感。应综合各脆性指数公式并结合地层物性信息，以达到最优的预测结果。
Abstract：
The construction of a shale rock physics model and the selection of an appropriate brittleness index (BI) are two significant steps that can influence the accuracy of brittleness prediction. On one hand, the existing models of kerogen-rich shale are controversial, so a reasonable rock physics model needs to be built. On the other hand, several types of equations already exist for predicting the BI whose feasibility needs to be carefully considered. This study constructed a kerogen-rich rock physics model by performing the self-consistent approximation and the differential effective medium theory to model intercoupled clay and kerogen mixtures. The feasibility of our model was confirmed by comparison with classical models, showing better accuracy. Templates were constructed based on our model to link physical properties and the BI. Different equations for the BI had different sensitivities, making them suitable for different types of formations. Equations based on Young’s Modulus were sensitive to variations in lithology, while those using Lame’s Coefficients were sensitive to porosity and pore fluids. Physical information must be considered to improve brittleness prediction.
. Prediction of brittleness based on anisotropic rock physics model for kerogen-rich shale[J]. APPLIED GEOPHYSICS, 2017, 14(4): 463-480.
[1]
Bandyopadhyay, K., 2009, Seismic anisotropy: Geological causes and its implications to reservoir geophysics: PhD Thesis, Stanford University.
[2]
Ba, J., Carcione, J. M., and Nie, J. X., 2011, Biot-Rayleigh theory of wave propagation in double-porosity media: Journal of Geophysical Research Solid Earth, 116(B6), B06202.
[3]
Ba, J., Cao, H., Yao, F. C., Nie, J. X., and Yang, H. Z., 2008, Double-porosity rock model and squirt flow in the laboratory frequency band: Applied Geophysics, 5(4), 261−276.
[4]
Backus, G. E., 1962, Long-wave elastic anisotropy produced by horizontal layering: Jounal of Geophysical Research, 67(11), 4427−4440.
[5]
Brown, R., and Korringa, J., 1975, On the dependence of the elastic properties of a porous rock on the compressibility of the pore fluid: Geophysics, 40(4), 608−616.
[6]
Chen, J. J., Zhang, G. Z., Chen H. Z., and Yin, X. Y., 2014, The Construction of Shale Rock Physics Effective Model and Prediction of Rock Brittleness: 84th Annual International Meeting, SEG, Expanded Abstracts, 2861−2865.
[7]
Goodway, B., Perez, M., and Varsek, J., 2010, Seismic petrophysics and isotropic-anisotropic AVO methods for unconventional gas exploration: Leading Edge, 29(12), 1500−1508.
[8]
Goodway, B., Chen, T., and Downton, J., 1999, Improved AVO fluid detection and lithology discrimination using Lamé petrophysical parameters; “λρ”,“μρ”, &“λ/μ fluid stack”, from P and S inversions: 69th Annual International Meeting, SEG, Expanded Abstracts, 16(1), 2067.
[9]
Guo, Z., and Li, X. Y., 2015, Rock physics model-based prediction of shear wave velocity in the Barnett Shale formation: Journal of Geophysics & Engineering, 12(3).
[10]
Guo, Z., Chapman, M., and Li, X. Y., 2012a, A shale rock physics model and its application in the prediction of brittleness index, mineralogy, and porosity of the Barnet Shale: 82th Annual International Meeting, SEG, Expanded Abstracts, 1−5.
[11]
Guo, Z., Chapman, M., and Li, X. Y., 2012b, Exploring the effect of fractures and microstructure on brittleness index in the Barnett Shale: 82th Annual International Meeting, SEG, Expanded Abstracts, 1−5.
[12]
Hashin, Z., and Shtrikman, S., 1963, A variational approach to the elastic behavior of multiphase materials: Mech Phys Solids, 11, 127−140.
[13]
Hornby, B., Schwartz, L., and Hundson, J., 1994, Anisotropic effective-medium modeling of the elastic properties of shales: Geophysics, 59, 1570−83.
[14]
Huang, X. R., Huang, J. P., Li, Z. C., et al., 2015, Brittleness index and seismic rock physics model for anisotropic tight-oil sandstone reservoirs: Applied Geophysics, 12(1), 11−22.
[15]
Johansen, T. A., Ruud, B. O., and Jakobsen, M., 2004, Effect of grain scale alignment on seismic anisotropy and reflectivity of shales: Geophysical Prospecting, 52(2), 133−149.
[16]
Qian, K., Zhang, F., Li, X. Y., et al., 2014, A Rock Physics Model for Estimating Elastic Properties of Organic Shales: 76th EAGE Conference & Exhibition Extended Abstract. Th D203 03.
[17]
Liu, Z. and Sun, Z., 2015, New brittleness index Brittleness Indexes and their application in shale/clay gas reservoir prediction: Petroleum Exploration and Development(in Chinese), 117−124.
[18]
Mavko, G., Mukerji, T., and Dvorkin, J., 2009, The rock physics handbook: Tools for seismic analysis of porous media. Cambridge University Press, England.
[19]
Rickman, R., Mullen, M. J., Petre, J. E., et al., 2008, A practical use of shale petrophysics for stimulation design optimization: All shale plays are not clones of the Barnett Shale: Annual Technical Conference and Exhibition. Society of Petroleum Engineers, SPE 115258.
[20]
Sayers, C. M., 1994, The elastic anisotropy of shales: Journal of Geophysical Research Atmospheres, 99, 767-774.
[21]
Sayers, C. M., 2005, Seismic anisotropy of shales: Geophysical Prospecting, 53(5), 667−676.
[22]
Sayers, C. M., 2013, The effect of kerogen on the elastic anisotropy of organic-rich shales: Geophysics., 78(78), 65−74.
[23]
Sun, C. Y., 2007, Theory and Methods of seismic Waves. China University of Petroleum of Press, Dong Ying.
[24]
Sondergeld, C. H., and Rai, C. S., 2011, Elastic anisotropy of shales: The Leading Edge., 30(3), 324−331.
[25]
Vanorio, T., Mukerji, T., and Mavko, G., 2008, Emerging methodologies to characterize the rock physics properties of organic-rich shales: The Leading Edge: 27(6), 780−787.
[26]
Vernik, L., and Nur, A., 1992, Petrophysical analysis of the Cajon Pass Scientific Well: Implications for fluid flow and seismic studies in the continental crust: Journal of Geophysical Research Atmospheres, 97(B4), 5121−5134.
[27]
Vernik, L., and Liu, X., 1997, Velocity anisotropy in shales: A petrophysical study. Geophysics, 62(2), 521−532.
[28]
Vernik, L., and Landis, C., 1996, Elastic anisotropy of source rocks: Implications for hydrocarbon generation and primary migration: AAPG Bulletin, 80(4), 531−544.
[29]
Wu, X., Chapman, M., Li, X. Y., et al., 2012, Anisotropic elastic modelling for organic shales: 74th EAGE Conference and Exhibition.
[30]
Xu, S., and Payne, M. A., 2009, Modeling elastic properties in carbonate rocks: The Leading Edge, 28(1), 66−74.
[31]
Zhu, Y., Xu, S., Payne, M., et al., 2012, Improved rock-physics model for shale gas reservoirs: 82th Annual International Meeting, SEG, Expanded Abstracts, 1−5.
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