QUANTIFYING THE INFLUENCE OF CLAY-BOUND WATER ON WAVE DISPERSION AND ATTENUATION SIGNATURES OF SHALE: AN EXPERIMENTAL STUDY

IF 3 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Geophysics Pub Date : 2023-12-13 DOI:10.1190/geo2022-0646.1

Teng Long, Xuan Qin, Q. Wei, Luanxiao Zhao, Yang Wang, Feng Chen, Michael T. Myers, Yingcai Zheng, De-Hua Han

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引用次数: 0

Abstract

Understanding the elastic and attenuation signatures of shales is of considerable interest for unconventional reservoir characterization and sealing capacity evaluation for CO2 sequestration and nuclear waste disposal. We conducted laboratory measurements on seven shale samples at seismic frequencies (2100 Hz) to study the effects of clay-bound water (CBW) on their wave dispersion and attenuation signatures. With Nuclear Magnetic Resonance (NMR) and helium porosimeter, the volume of CBW in the shale samples is quantified. The forced-oscillation measurement reveals that Youngs modulus exhibits a continuous dispersion trend from 2 to 100 Hz. The extensional attenuation [Formula: see text] shows a weak frequency- and pressure-dependence on effective pressure ranging from 5 to 35 MPa. The magnitude of extensional attenuation shows a positive correlation with CBW, with an R-square value of 0.89. It is found that 4% of CBW in the rock frame causes roughly a 5% modulus increase from 2 to 100 Hz. We adopt a constant Q model for assigning frequency-dependent bulk and shear moduli to the CBW in the rock physics modeling, which can fit the experimental data of modulus dispersion and attenuation well, indicating that both the bulk and shear moduli of CBW in shales might behave viscoelastically.

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量化粘土结合水对波浪扩散和页岩衰减特征的影响：一项实验研究

了解页岩的弹性和衰减特征对于非常规储层特征描述以及二氧化碳封存和核废料处理的密封能力评估具有重要意义。我们对七个页岩样本进行了地震频率（2100 Hz）的实验室测量，以研究粘土结合水（CBW）对其波色散和衰减特征的影响。通过核磁共振（NMR）和氦气孔隙度计，对页岩样本中的粘土结合水体积进行了量化。强制振荡测量显示，杨氏模量在 2 到 100 Hz 范围内呈现连续的频散趋势。延伸衰减[计算公式：见正文]在 5 至 35 兆帕的有效压力范围内显示出微弱的频率和压力依赖性。延伸衰减的大小与 CBW 呈正相关，R 方值为 0.89。研究发现，岩框中 4% 的 CBW 会导致 2 至 100 Hz 的模量增加约 5%。在岩石物理建模中，我们采用恒定 Q 模型为 CBW 分配随频率变化的体积模量和剪切模量，该模型能很好地拟合模量离散和衰减的实验数据，表明页岩中 CBW 的体积模量和剪切模量都可能具有粘弹性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geophysics 地学-地球化学与地球物理

CiteScore

6.90

自引率

18.20%

发文量

354

审稿时长

3 months

期刊介绍： Geophysics, published by the Society of Exploration Geophysicists since 1936, is an archival journal encompassing all aspects of research, exploration, and education in applied geophysics. Geophysics articles, generally more than 275 per year in six issues, cover the entire spectrum of geophysical methods, including seismology, potential fields, electromagnetics, and borehole measurements. Geophysics, a bimonthly, provides theoretical and mathematical tools needed to reproduce depicted work, encouraging further development and research. Geophysics papers, drawn from industry and academia, undergo a rigorous peer-review process to validate the described methods and conclusions and ensure the highest editorial and production quality. Geophysics editors strongly encourage the use of real data, including actual case histories, to highlight current technology and tutorials to stimulate ideas. Some issues feature a section of solicited papers on a particular subject of current interest. Recent special sections focused on seismic anisotropy, subsalt exploration and development, and microseismic monitoring. The PDF format of each Geophysics paper is the official version of record.