任舒波^1,,
韩同城^1,2,,,
符力耘^1,2,
颜韩¹
1. 中国石油大学(华东)地球科学与技术学院, 山东青岛 266580
2. 青岛海洋科学与技术试点国家实验室海洋矿产资源评价与探测技术功能实验室, 山东青岛 266071

基金项目: 国家自然科学基金(41874151，41821002)，中央高校基本科研业务费(18CX05008A)资助


详细信息

作者简介: 任舒波, 男, 1996年生, 硕士在读, 主要从事岩石物理声学性质研究.E-mail: 921837023@qq.com

通讯作者: 韩同城, 男, 1982年生, 教授, 博士生导师, 主要从事岩石物理学、岩石声电联合性质、岩石和沉积物的物理性质研究.E-mail: hantc@upc.edu.cn

中图分类号: P631

收稿日期:2020-09-28
修回日期:2021-05-14
上线日期:2021-07-10

Pressure effects on the anisotropic velocities of rocks with aligned fractures

REN ShuBo^1,,
HAN TongCheng^1,2,,,
FU LiYun^1,2,
YAN Han¹
1. School of Geosciences, China University of Petroleum(East China), Shandong Qingdao 266580, China
2. Laboratory for Marine Mineral Resources, Pilot National Laboratory for Marine Science and Technology, Shandong Qingdao 266071, China


More Information

Corresponding author: HAN TongCheng,E-mail:hantc@upc.edu.cn

MSC: P631

--> Received Date: 28 September 2020
Revised Date: 14 May 2021
Available Online: 10 July 2021


摘要
摘要:深入了解压力作用下裂缝性岩石的声学各向异性，在地球物理应用中具有重要意义.本文基于各向异性微分等效介质模型，结合不同压力下含硬币状定向排列裂缝岩石以及不含裂缝岩石在不同方向上的超声速度测量数据，计算得到不同压力下的裂缝参数，并进一步分析了压力引起的裂缝参数的改变，及其对岩石各向异性速度的影响.结果表明，岩石的裂缝密度与裂缝纵横比随着压力的增加呈现指数减小，并且裂缝纵横比与裂缝密度之间线性相关；模型计算结果发现，当岩石所受压力增加时，随着裂缝密度的减小，不同方向的岩石速度呈现不同程度的增加，其中垂直裂缝方向纵波速度的增加最为明显，随着裂缝纵横比的减小，不同方向的岩石速度基本不变；压力增大引起的裂缝密度的降低使岩石的各向异性参数减小，岩石整体的各向异性随之降低.
关键词: 压力/
裂缝密度/
裂缝纵横比/
各向异性速度/
各向异性微分等效介质模型

Abstract:Understanding the pressure-dependent anisotropic acoustic properties of fractured rocks is of great importance in a range of geophysical applications. Using the anisotropic differential effective medium model, and based on published experimental data of the pressure dependent anisotropic ultrasonic velocities of dry rocks with and without aligned penny-shaped fractures, we calculated the crack density and crack aspect ratio with varying pressure. We also studied theoretically the effects of the pressure-dependent fracture parameters on the anisotropic acoustic properties of fractured rocks. The results showed that crack density decreases exponentially while crack aspect ratio reduces linearly with increasing pressure. We also showed that all the five anisotropic velocities increase to different degrees with decreasing crack density resulting from the increasing pressure, where the most significant increase is found for the P-wave velocity propagating in the direction vertical to the fractures. The reducing crack aspect ratio as a result of increasing pressure showed negligible impact on the velocities, and the anisotropy parameters were found to gradually decrease with the decrease of the crack density caused by the increasing pressure, the anisotropy of the rock decreases.
Key words:Pressure/
Crack density/
Crack aspect ratio/
Anisotropic velocities/
Anisotropic differential effective medium model



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