伍宇明^1,,
兰恒星^1,2,,,
黄为清³
1. 中国科学院地理科学与资源研究所资源与环境信息系统国家重点实验室, 北京 100101
2. 西安大学地质工程与测绘学院, 西安 710054
3. 中国科学院地质与地球物理研究所, 北京 100029

基金项目: 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


详细信息

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

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

中图分类号: P631

收稿日期:2019-07-29
修回日期:2019-12-11
上线日期:2020-05-05

Discussion on the relationship between elastic anisotropy and mineral distribution of Longmaxi Shale

WU YuMing^1,,
LAN HengXing^1,2,,,
HUANG WeiQing³
1. State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Adademy of Sciences, Beijing 100101, China
2. School of Geological Engineering and Geomatics, Chang'an University, Xi'an 710064, China
3. Institute of Geology And Geophysics, Chinese Adademy of Sciences, Beijing 100029, China


More Information

Corresponding author: LAN HengXing,E-mail:lanhx@lreis.ac.cn

MSC: P631

--> Received Date: 29 July 2019
Revised Date: 11 December 2019
Available Online: 05 May 2020


摘要
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.
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



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