| 摘要: |
| 为了研究水平裂缝对声波波形的影响规律,把裂缝当作线性滑动界面,模拟在含有裂缝的地层中全波列声波测井响应。建立柱坐标系下穿过井孔的水平单条裂缝和多条裂缝计算模型,采用有限差分法模拟声波的传播,记录声波波形。通过分析不同源距、不同宽度裂缝和不同裂缝条数条件下透射波和反射波的波形变化,研究裂缝对纵波、横波和斯通利波波形的影响规律。结果表明:采用线性滑动模型描述的裂缝对纵波的影响很小,只有靠近裂缝的透射纵波幅度会发生改变;裂缝不仅引起横波很强的衰减和反射,而且使横波的相位发生了改变;接收器距离裂缝越远,横波的衰减越大;当裂缝延伸距离很短时,透射横波的幅度和相位随着裂缝延伸距离的改变会发生变化;裂缝也会引起斯通利波的衰减和反射,透射斯通利波对线性滑动裂缝的宽度变化不敏感,而对裂缝条数变化敏感。 |
| 关键词: 线性滑动模型 声波测井 有限差分 裂缝 |
| DOI：10.3969/j.issn.1673-5005.2019.03.006 |
| 分类号::P 631 |
| 文献标识码:A |
| 基金项目:国家自然科学基金项目(41874135) |
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| Numerical simulation of acoustic logging in fractured formation based on linear-slip model |
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OU Weiming, WANG Zhuwen, NING Qinqin, XU Fanghui, YU Yang
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(College of Geoexploration Science and Technology, Jilin University, Changchun 130026, China)
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| Abstract: |
| To study the effects of horizontal fractures on acoustic logging waveforms, the full-wave acoustic logging responses in fractured formations are simulated based on a linear-slip model. Models of single and multiple fractures passing through borehole in a cylindrical coordinate system are computed. A finite-difference time domain method is used to simulate the propagation of acoustic logging waves.The waveform variations of transmitted and reflected waves with respect to source distance, aperture size,extended fracture distance and the number of fractures are analyzed. The effects of fractures described by the linear-slip model on the P-wave, S-wave and Stoneley wave waveforms are studied.The results show that the effects of linear-slip fractures on acoustic logging waveforms are as follows:the effect of fracturing on the P-wave is very small, and only the amplitude of transmitted P-wave near the fracture will change; fractures not only have strong attenuation and reflection effects on the S-waves, but also change the phase of shear waves;the greater the distance from fracture, the greater the attenuation of shear waves; when the extended distance of fracture is very small, the amplitude and phase of transmitted shear wave will depend on the variations in the extended distance; linear-slip fractures also have strong attenuation and reflection effects on the Stoneley waves, however, the transmitted Stoneley waves are not sensitive to the fracture aperture, but to the number of fractures. |
| Key words: linear-slip model acoustic logging finite-difference fracture |
