Data from: Assessment of dynamic material properties of intact rocks using seismic wave attenuation: an experimental study

The mechanical properties of any substance are essential facts to understand its behaviour and make the maximum use of the particular substance. Rocks are indeed an important substance, as they are of significant use in the energy industry, specifically for fossil fuels and geothermal energy. Attenuation of seismic waves is a non-destructive technique to investigate mechanical properties of reservoir rocks under different conditions. The attenuation characteristics of five different rock types, siltstone, shale, Australian sandstone, Indian sandstone and granite, were investigated in the laboratory using ultrasonic and acoustic emission instruments in a frequency range of 0.1–1 MHz. The pulse transmission technique and spectral ratios were used to calculate the attenuation coefficient (α) and quality factor (Q) values for the five selected rock types for both primary (P) and secondary (S) waves, relative to the reference steel sample. For all the rock types, the attenuation coefficient was linearly proportional to the frequency of both the P and S waves. Interestingly, the attenuation coefficient of granite is more than 22% higher than that of siltstone, sandstone and shale for both P and S waves. The P and S wave velocities were calculated based on their recorded travel time, and these velocities were then used to calculate the dynamic mechanical properties including elastic modulus (E), bulk modulus (K), shear modulus (µ) and Poisson's ratio (ν). The P and S wave velocities for the selected rock types varied in the ranges of 2.43–4.61 km s−1 and 1.43–2.41 km h−1, respectively. Furthermore, it was observed that the P wave velocity was always greater than the S wave velocity, and this confirmed the first arrival of P waves to the sensor. According to the experimental results, the dynamic E value is generally higher than the static E value obtained by unconfined compressive strength tests.

任何物质的力学性能都是认知其行为特性、实现其高效利用的核心基础数据。岩石作为一类重要的天然物质，在能源工业中应用广泛，尤其在化石燃料与地热能开发领域具有重要价值。地震波衰减是一种无损检测技术，可用于研究不同工况下储集层岩石的力学性能。本研究在实验室环境下，采用超声与声发射仪器，在0.1~1 MHz的频率范围内，对粉砂岩、页岩、澳大利亚砂岩、印度砂岩及花岗岩这五种岩石的衰减特性开展了测试分析。以标准钢样作为参照，本研究采用脉冲透射法与频谱比法，计算了五种受试岩石的纵波（primary wave, P波）与横波（secondary wave, S波）的衰减系数（attenuation coefficient, α）及品质因数（quality factor, Q）。对于所有受试岩石，其衰减系数与纵波、横波的频率均呈线性正相关关系。值得注意的是，无论是纵波还是横波，花岗岩的衰减系数均比粉砂岩、砂岩及页岩高出22%以上。研究人员基于记录的波传播时间计算了纵波与横波的波速，并进一步基于波速计算了动态力学性能参数，包括弹性模量（elastic modulus, E）、体积模量（bulk modulus, K）、剪切模量（shear modulus, μ）及泊松比（Poisson's ratio, ν）。五种受试岩石的纵波波速范围为2.43~4.61 km·s⁻¹，横波波速范围为1.43~2.41 km·s⁻¹（原文此处标注为km·h⁻¹，结合岩石波速常识判断为笔误，已修正为km·s⁻¹）。此外，测试结果显示纵波波速始终大于横波波速，这也印证了纵波会率先抵达传感器。实验结果表明，动态弹性模量普遍高于通过单轴抗压强度试验获得的静态弹性模量。