Imaging of small-scale heterogeneities is important for the geological exploration in complex environments. It requires a processing sequence tuned to high-resolution model building. Conventional methods which use refractions or reflections might face problems in resolving small-scale features since they are visually close to the resolution of the reflection images. Additional information or an unconventional technology, which supports the reflection imaging, is thus of great interest. An unconventional method based on seismic diffractions naturally complements specular reflection imaging. Diffracted waves represent a direct seismic response from small-scale subsurface heterogeneities, such as inclusions with a characteristic size of the prevailing wavelength, or discontinuities in geological interfaces, such as faults and fractures. We investigate the rule of diffracted part of the wavefield on velocity model building using a full-waveform inversion (FWI) example. In order to best acknowledge refracted and reflected parts of the wavefield in FWI, we chose a synthetic data example which mimics the ocean-bottom nodes acquisition survey as it provides almost perfect conditions for FWI of diving waves, a standard tool for high-resolution model building. We show, that FWI using diving waves produces a well-resolved anomaly. Including other part of the wavefield, reflected waves, further improves the resolution of the velocity anomaly but also leads to a gentle overfitting due to missing illumination from the very steep anomaly flanks. Considering diffracted events in FWI improves the model resolution even further resulting in a detailed velocity model and correctly imaged anomaly in both vertical and lateral directions.

小型异质性成像对于复杂环境中的地质勘探非常重要。它需要调整为高分辨率模型构建的处理序列。使用折射或反射的常规方法在分辨小尺寸特征时可能会遇到问题，因为它们在视觉上接近反射图像的分辨率。因此，人们非常关注支持反射成像的其他信息或非常规技术。基于地震衍射的非常规方法自然可以补充镜面反射成像。衍射波表示来自小规模地下异质性的直接地震响应，例如具有普遍波长特征尺寸的包裹体，或诸如断层和裂缝等地质界面的不连续性。我们使用全波形反演（FWI）示例研究了波场的衍射部分在速度模型构建上的规则。为了最好地识别FWI中波场的折射和反射部分，我们选择了一个模拟海洋底节点采集调查的综合数据示例，因为它为潜水波的FWI提供了几乎完美的条件，这是高分辨率模型的标准工具建造。我们证明，使用潜水波的FWI产生了一个很好解决的异常。包括波场的其他部分在内，反射波进一步提高了速度异常的分辨率，但由于非常陡峭的异常侧面缺少照明，因此导致平缓的过拟合。