The ability to image near-wellbore fractures is critical for wellbore integrity monitoring as well as for energy production and waste disposal. Single-well imaging uses a sonic logging instrument consisting of a source and a receiver array to image geologic structures around a wellbore. We use cross-dipole sources because they can excite waves that can be used to image structures farther away from the wellbore than traditional monopole sources. However, the cross-dipole source also will excite large-amplitude, slowly propagating dispersive waves along the surface of the borehole. These waves will interfere with the formation reflection events. We have adopted a new fracture imaging procedure using sonic data. We first remove the strong amplitude borehole waves using a new nonlinear signal comparison method. We then apply Gaussian beam migration to obtain high-resolution images of the fractures. To verify our method, we first test our method on synthetic data sets modeled using a finite-difference approach. We then validate our method on a field data set collected from a fractured natural gas production well. We are able to obtain high-quality images of the fractures using Gaussian beam migration compared with Kirchhoff migration for the synthetic and field data sets. We also found that a low-frequency source (around 1 kHz) is needed to obtain a sharp image of the fracture because high-frequency wavefields can interact strongly with the fluid-filled borehole.

中文翻译：

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消除分散井孔波后，使用声波测井工具对井眼附近的裂缝进行高斯成像

对井眼附近裂缝成像的能力对于井眼完整性监控以及能源生产和废物处置至关重要。单井成像使用由声源和接收器阵列组成的声波测井仪器对井眼周围的地质结构成像。我们使用交叉偶极子源，因为它们可以激发比传统单极子源更能用来成像远离井眼的结构的波。但是，交叉偶极子源也会激发大幅度的，沿着井眼表面缓慢传播的色散波。这些波将干扰地层反射事件。我们采用了声波数据，采用了新的裂缝成像方法。我们首先使用一种新的非线性信号比较方法来消除强振幅井眼波。然后，我们应用高斯光束偏移来获得高分辨率的裂缝图像。为了验证我们的方法，我们首先在使用有限差分方法建模的综合数据集上测试了我们的方法。然后，我们根据从压裂天然气生产井收集的现场数据集验证我们的方法。与合成和现场数据集的基尔霍夫偏移相比，我们可以使用高斯光束偏移获得高质量的裂缝图像。我们还发现，需要一个低频源（大约1 kHz）来获得清晰的裂缝图像，因为高频波场可以与充满流体的钻孔强烈相互作用。然后，我们根据从压裂天然气生产井收集的现场数据集验证我们的方法。与合成和现场数据集的基尔霍夫偏移相比，我们可以使用高斯光束偏移获得高质量的裂缝图像。我们还发现，需要一个低频源（大约1 kHz）以获得清晰的裂缝图像，因为高频波场可以与充满流体的井眼强烈地相互作用。然后，我们根据从压裂天然气生产井收集的现场数据集验证我们的方法。与合成和现场数据集的基尔霍夫偏移相比，我们可以使用高斯光束偏移获得高质量的裂缝图像。我们还发现，需要一个低频源（大约1 kHz）来获得清晰的裂缝图像，因为高频波场可以与充满流体的钻孔强烈相互作用。