郑懿^1,2,,
曹俊兴^1,2,,,
何晓燕²
1. "油气藏地质开发工程"国家重点实验室(成都理工大学), 成都 610059
2. 成都理工大学地球物理学院, 成都 610059

基金项目: 国家自然科学基金项目（40930424，41774192）资助


详细信息

作者简介: 郑懿, 男, 1980年生, 博士研究生, 主要从事油气运移与岩石物理研究.E-mail:nkzhy@mail.nankai.edu.cn

通讯作者: 曹俊兴, 男, 教授, 博士生导师, 主要从事地球探测与信息技术研究.E-mail:caojx@cdut.edu.cn

中图分类号: P631

收稿日期:2017-08-13
修回日期:2017-12-16
上线日期:2018-10-05

Study of the time-evolution of underground rock fractal permeability after the earthquakes

ZHENG Yi^1,2,,
CAO JunXing^1,2,,,
HE XiaoYan²
1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China
2. College of Geophysics, Chengdu University of Technology, Chengdu 610059, China


More Information

Corresponding author: CAO JunXing,E-mail:caojx@cdut.edu.cn

MSC: P631

--> Received Date: 13 August 2017
Revised Date: 16 December 2017
Available Online: 05 October 2018


摘要
摘要:天然地震发生后，地震波及区域内的地下岩层渗透率常常会发生显著改变，其变化曲线显示出独有的特征，造成这一现象的机理较为复杂，传统渗流理论尚不能给出合理解释.针对这一问题，从震后渗透率变化规律入手，深入分析了地下岩层裂缝体系对渗透率的影响，给出了裂缝结构参数与渗透率之间的定量关系.结合岩层黏弹特性以及天然地震所产生的地下岩层体应变特征，基于裂缝体系分维度正比于外部应力的实验事实，将黏弹体应力松弛机制引入该体系，对裂缝分形渗透率模型进行了含时推广，建立起震后地下岩层渗透率的时间演化模型，理论预测曲线与实验曲线吻合较好.在此基础上提出‘分形裂缝渗透率松弛效应’这一全新概念.本研究为震控流体运移研究提供了新思路，对于揭示震后断层恢复机制，探讨断层活动与孕震的关联有一定的理论价值和现实意义.
关键词: 天然地震/
渗透率异常/
分形渗透率/
分维度/
时间演化

Abstract:After the natural earthquakes, the permeability of underground rock in the affected area often changes remarkably. The time evolution curve of permeability shows unique characteristics. The mechanism of this anomaly is so complicated that the traditional percolation theory cannot give a reasonable explanation. In response to this problem, starting with the law of permeability change after earthquakes, we analyze the influence of rock fracture system on permeability and acquire the quantitative relation between the fracture parameters and permeability. Because of the fact that the fractal dimension is proportional to the external stress, by combining the underground rock viscoelastic characteristics and the body strain generated by earthquake, the time-dependent generalization has been done to the fractal crack permeability model. We introduce the stress relaxation mechanism into the rock system to establish the time evolution model of permeability after the earthquake, and the theoretical result agrees well with the experimental data. On this basis, a new concept of relaxation effect of fractal permeability is proposed. This model provides a new way for the research on earthquake fluid migration. It has both theoretical value and practical significance for revealing the mechanism of fault recovery after the earthquake and the earthquake preparation.
Key words:Natural earthquake/
Permeability anomaly/
Fractal permeability/
Fractal dimension/
Time evolution



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