Shale formation properties are crucial for the hydrocarbon production performance of unconventional reservoirs. Microseismic-induced guided waves, which propagate within the low-velocity shale formation, are an ideal candidate for accurate estimation of shale thickness, velocity, and anisotropy. A distributed acoustic sensing fiber deployed along the horizontal section of a monitor well can provide a high-resolution recording of guided waves excited by microseismic events during hydraulic fracturing operations. These guided waves manifest a highly dispersive behavior that allows for seismic inversion of the shale formation properties. An adaptation of the propagator matrix method is presented to estimate guided-wave dispersion curves, and its accuracy is validated by comparison to 3D elastic wavefield simulations. The propagator matrix formulation holds for cases of vertical transverse isotropy (VTI) as well. A sensitivity analysis of the theoretical dispersion relations of the guided waves indicates that they are mostly influenced by the thickness and S-wave velocity of the low-velocity shale reservoir. The VTI parameters of the formation are also shown to have an impact on the dispersion relations. These physical insights provide the foundation for a dispersion-based model inversion for a 1D depth-dependent structure of the reservoir and its surroundings. The inversion procedure is validated in a synthetic case and applied to the field records collected in an Eagle Ford hydraulic fracturing project. The inverted structure agrees well with a sonic log acquired several hundred meters away from the monitor well. Therefore, seismic inversion using guided-wave dispersion indicates promise to become a novel and cost-effective strategy for in situ estimation of reservoir structure and properties, which complements microseismic-based interpretation and production-related information.

中文翻译：

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利用分布式声学传感记录的微震诱导导波进行页岩储层性质的地震反演

页岩地层特性对非常规储层的油气生产性能至关重要。在低速页岩地层内传播的微震诱导导波是准确估计页岩厚度、速度和各向异性的理想选择。沿着监测井的水平部分部署的分布式声学传感光纤可以提供在水力压裂作业期间由微地震事件激发的导波的高分辨率记录。这些导波表现出高度分散的行为，允许对页岩地层特性进行地震反演。传播器矩阵方法的改编被提出来估计导波色散曲线，并通过与 3D 弹性波场模拟进行比较来验证其准确性。传播矩阵公式也适用于垂直横向各向同性 (VTI) 的情况。导波理论频散关系敏感性分析表明，导波主要受低速页岩储层厚度和横波速度影响。地层的 VTI 参数也显示出对色散关系的影响。这些物理见解为基于弥散的模型反演提供了基础，用于对储层及其周围环境的一维深度相关结构进行反演。反演程序在合成案例中得到验证，并应用于在 Eagle Ford 水力压裂项目中收集的现场记录。倒置结构与在距监测井数百米处获得的声波测井非常吻合。所以，