龙马溪页岩弹性各向异性与矿物分布之间的关系探讨

doi:10.6038/cjg2020N0105

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摘要岩石弹性各向异性特征是普遍存在的，但导致岩石弹性各向异性的原因复杂且仍然存在一定争议.本研究以龙马溪页岩为例，试图建立页岩弹性各向异性和矿物分布之间关系.研究使用无损超声波探测获取岩石弹性各向异性参数，并使用背散射技术获取岩石矿物分布特征.研究通过引进变异系数来描述矿物或孔裂隙在不同方向的差异性，并通过2个正交方向的变异系数建立微观异质性指标，用于表征微观尺度上矿物或孔裂隙在不同方向的差异程度.微观背散射图像显示，龙马溪组页岩主要由石英和伊利石构成，且这两种矿物和孔裂隙在X和Y面上都有定向排列特征.相应地，它们的变异系数在X面和Y面上均表现出随角度增大而降低的特征；而在Z面，石英、伊利石和孔裂隙变异系数变化不明显，这与Z面上矿物和孔裂隙无明显方向性的特点一致.无损超声波探测结果显示，波速在X和Y面上随角度增加而减小，这与主要矿物和孔裂隙变异系数变化趋势相同；而在Z面，波速变化不大，与主要矿物和孔裂隙变异系数变化不明显的特征一致.以上观测结果说明，宏观波速与矿物的微观变异系数明显相关，暗示岩石弹性各向异性与矿物分布直接相关.

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关键词 ：波速, 矿物分布, 异质性, 各向异性

Abstract：Anisotropy is a common characteristic of rock elasticity. However, the factors inducing elastic anisotropy of rocks are complex and still controversial. This paper aims to inspect the relationship between elastic anisotropy and mineral distributions of rocks using the Longmaxi Shale from Chongqing, China. The mineral distributions on three orthogonal directions were obtained by AmicSCAN (a back scattered electron detector) on 3 mm×3 mm×1 mm samples, and the P-wave and S-wave velocities, which characterize rock elasticity, were measured by Panametrics-NDT transducer. A variation coefficient was introduced to characterize the variation of minerals and fractures in certain directions. The variation indices in two orthogonal directions were used to establish a heterogeneity index to characterize the difference of minerals and pores in different directions. The micro back scattered images showed that the Longmaxi shale was mainly composed of quartz and illite, and both the two principal minerals and pores are well-oriented on the X-plane and Y-plane. In addition, both the variable coefficients of the two principal minerals and pores decrease with the increase of the angle to the direction of the large principal stress on the X-plane and Y-plane. However, there are no differences in variable coefficients on the Z-plane. In term of acoustic characteristics, the velocities and anisotropy indexes show similar rules, which may be related to the heterogeneity of distributions of quartz, clay minerals, and pores. These results indicated that the elastic anisotropy was caused by minerals, pore and crack distribution.

Key words： Acoustics velocity Mineral distribution Heterogeneity Anisotropy

收稿日期: 2019-07-29

PACS:

P631

基金资助:国家自然科学基金（41701458，41525010，41927806），中科院战略性先导科技专项（B类）（XDB10030300），资源与环境信息系统国家重点实验室青年人才培养基金（O88RAA0EYA）和资源与环境信息系统国家重点实验室自主创新项目（O88RAA02YA），国家科技重大专项课题（2016ZX05024-001）共同资助.

通讯作者: 兰恒星,男,1972年生,研究员,从事工程地质和页岩气方面研究.E-mail:lanhx@lreis.ac.cn E-mail: lanhx@lreis.ac.cn

作者简介: 伍宇明,男,1989年生,助理研究员,从事页岩气和灾害方面研究.E-mail:wuym@lreis.ac.cn

链接本文:

http://www.geophy.cn//CN/10.6038/cjg2020N0105 或 http://www.geophy.cn//CN/Y2020/V63/I5/1856

Bascou J, Barruol G, Vauchez A, et al. 2001. EBSD-measured lattice-preferred orientations and seismic properties of eclogites. Tectonophysics, 342(1-2):61-80.
Burlini L, Kunze K. 2000. Fabric and seismic properties of Carrara marble mylonite. Physics and Chemistry of the Earth, Part A:Solid Earth and Geodesy, 25(2):133-139.
Chen J H, Lan H X, Macciotta R, et al. 2018. Anisotropy rather than transverse isotropy in Longmaxi shale and the potential role of tectonic stress. Engineering Geology, 247:38-47.
Coker D A, Torquato S, Dunsmuir J H. 1996. Morphology and physical properties of Fontainebleau sandstone via a tomographic analysis. Journal of Geophysical Research:Solid Earth, 101(B8):17497-17506.
Hornby B E, Schwartz L M, Hudson J A. 1994. Anisotropic effective-medium modeling of the elastic properties of shales. Geophysics, 59(10):1570-1583.
Hu Q, Chen X H, Li J Y. 2014. Shear wave velocity prediction for shale gas reservoirs based on anisotropic rock physics model. Geophysical Prospecting for Petroleum (in Chinese), 53(3):254-261.
Kwon O, Kronenberg A K, Gangi A F, et al. 2004. Permeability of illite-bearing shale:1. Anisotropy and effects of clay content and loading. Journal of Geophysical Research:Solid Earth, 109(B10):B10205, doi:10.1029/2004JB003052.
Lan H X, Martin C D, Hu B. 2010. Effect of heterogeneity of brittle rock on micromechanical extensile behavior during compression loading. Journal of Geophysical Research:Solid Earth, 115(B1):B01202, doi:10.1029/2009JB006496.
Lan H X, Wu Y M, Li Q W, et al. 2017. Reconstruction and fractal analysis for three dimensional fracture network of Longmaxi shale. Journal of Engineering Geology (in Chinese), 25(6):1557-1565.
Lan H X, Chen J H, Wu Y M. 2018. Spatial characterization of micro-and nanoscale micro-cracks in gas shale before and after triaxial Compression test. Journal of Engineering Geology (in Chinese), 26(1):24-35.
Lan H X, Chen J H, Macciotta R. 2019. Universal confined tensile strength of intact rock. Scientific Reports, 9(1):6170.
Li Q H, Chen M, Jin Y, et al. 2012. Rock mechanical properties and brittleness evaluation of shale gas reservoir. Petroleum Drilling Techniques (in Chinese), 40(4):17-22.
Liu C, Fu W, Guo Z Q, et al. 2018. Rock physics inversion for anisotropic shale reservoirs based on Bayesian scheme. Chinese J. Geophys. (in Chinese), 61(6):2589-2600, doi:10.6038/cjg2018L0176.
Liu X, Yang J. 2018. Shear wave velocity in sand:effect of grain shape. Géoechnique, 68(8):1-22.
Liu X, Zhang N, Lan H X. 2019. Effects of sand and water contents on the small-strain shear modulus of loess. Engineering Geology, 260:105202.
Lloyd G E, Kendall J M. 2005. Petrofabric-derived seismic properties of a mylonitic quartz simple shear zone:Implications for seismic reflection profiling. Geological Society, London, Special Publications, 240(1):75-94.
Madonna C, Almqvist B S G, Saenger E H. 2012. Digital rock physics:numerical prediction of pressure-dependent ultrasonic velocities using micro-CT imaging. Geophysical Journal International, 189(3):1475-1482.
Mah M, Schmitt D R. 2003. Determination of the complete elastic stiffnesses from ultrasonic phase velocity measurements. Journal of Geophysical Research:Solid Earth, 108(B1):ECV 6-1-ECV 6-11.
Markham M F. 1957. Measurement of elastic constants by the ultrasonic pulse method. British Journal of Applied Physics, 8(S6):S56.
Pera E, Mainprice D, Burlini L. 2003. Anisotropic seismic properties of the upper mantle beneath the Torre Alfina area (Northern Apennines, Central Italy). Tectonophysics, 370(1-4):11-30.
Reuss A. 1929. Berechnung der fließgrenze von mischkristallen auf grund der plastizitätsbedingung für einkristalle. ZAMM-Journal of Applied Mathematics and Mechanics/Zeitschrift für Angewandte Mathematik und Mechanik, 9(1):49-58.
Sayers C M. 1995. Anisotropic velocity analysis. Geophysical Prospecting, 43(4):541-568.
Sayers C M. 2013. The effect of kerogen on the elastic anisotropy of organic-rich shales. Geophysics, 78(2):D65-D74.
Sayers C M, den Boer L D. 2016. The elastic anisotropy of clay minerals. Geophysics, 81(5):C193-C203.
Sayers C M, den Boer L D. 2018. The elastic properties of clay in shales. Journal of Geophysical Research:Solid Earth, 123(7):5965-5974.
Shea W T Jr, Kronenberg A K. 1993. Strength and anisotropy of foliated rocks with varied mica contents. Journal of Structural Geology, 15(9-10):1097-1121.
Thomsen L. 1986. Weak elastic anisotropy. Geophysics, 51(10):1954-1966.
Valcke S L A, Casey M, Lloyd G E, et al. 2006. Lattice preferred orientation and seismic anisotropy in sedimentary rocks. Geophysical Journal International, 166(2):652-666.
Voigt W. 1928. Lehrbuch der Kristallphysik (BG Teubner Leipzig und Berlin) 980 S. Reproduced 1966 Spring Fachmedien Wiesbaden GmbH.
Wang H, Guo Y T, Wang L, et al. 2017. An experimental study on mechanical anisotropy of shale reservoirs at different depths. Rock and Soil Mechanics (in Chinese), 38(9):2496-2506.
Wu Y M, Lan H X, Gao X, et al. 2016. The relationship between the volume density of cracks and acoustic properties of the shale core samples from Fulin. Chinese J. Geophys. (in Chinese), 59(10):3891-3990, doi:10.6038/cjg20161032.
Zhang B, Guo Z Q, Xu C, et al. 2018. Fracture properties and anisotropic parameters inversion of shales based on rock physics model. Journal of Jilin University (Earth Science Edition) (in Chinese), 48(4):1244-1252.
Zhong X, Frehner M, Kunze K, et al. 2014. A novel EBSD-based finite-element wave propagation model for investigating seismic anisotropy:Application to Finero Peridotite, Ivrea-Verbano Zone, Northern Italy. Geophysical Research Letters, 41(20):7105-7114.
Zhu W, Shan R. 2016. Digital core based transmitted ultrasonic wave simulation and velocity accuracy analysis. Applied Geophysics, 13(2):375-381.
Zhubayev A, Houben M E, Smeulders D M J, et al. 2016. Ultrasonic velocity and attenuation anisotropy of shales, Whitby, United Kingdom. Geophysics, 81(1):D45-D56.
附中文参考文献
胡起, 陈小宏, 李景叶. 2014. 基于各向异性岩石物理模型的页岩气储层横波速度预测. 石油物探, 53(3):254-261.
兰恒星, 伍宇明, 李全文等. 2017. 龙马溪组页岩三维缝网重构及分形分析. 工程地质学报, 25(6):1557-1565.
兰恒星, 陈俊辉, 伍宇明. 2018. 三轴压缩试验前后含气页岩微纳尺度裂隙空间分布特征研究. 工程地质学报, 26(1):24-35.
李庆辉, 陈勉, 金衍等. 2012. 页岩气储层岩石力学特性及脆性评价. 石油钻探技术, 40(4):17-22. 本条文献在正文中未被引用
刘财, 符伟, 郭智奇等. 2018. 基于贝叶斯框架的各向异性页岩储层岩石物理反演技术. 地球物理学报, 61(6):2589-2600, doi:10.6038/cjg2018L0176.
汪虎, 郭印同, 王磊等. 2017. 不同深度页岩储层力学各向异性的试验研究. 岩土力学, 38(9):2496-2506.
伍宇明, 兰恒星, 高星等. 2016. 涪陵地区井下页岩岩芯裂缝体密度与声学性质关系实验研究. 地球物理学报, 59(10):3891-3900, doi:10.6038/cjg20161032.
张冰, 郭智奇, 徐聪等. 2018. 基于岩石物理模型的页岩储层裂缝属性及各向异性参数反演. 吉林大学学报(地球科学版), 48(4):1244-1252.