Abstract. We present the pre-stack depth imaging results for a case study of 3D reflection seismic exploration at the Blötberget iron-oxide mining site belonging to the Bergslagen mineral district in central Sweden. The goal of this case study is to directly image the ore-bearing units and to map its possible extension down to greater depths than known from existing boreholes. Therefore, we applied a tailored pre-processing workflow as well as two different seismic imaging approaches, Kirchhoff pre-stack depth migration and Fresnel Volume Migration (FVM). Both imaging techniques deliver a well resolved 3D image of the deposit and its host rock, where the FVM image yields a significantly better image quality compared to the KPSDM image. We were able to unravel distinct reflection horizons, which are linked to known mineralisation and provide insights on lateral and depth extent of the deposits beyond their known extension from borehole data. A comparison of the known mineralization and the image show a good agreement of the position and the shape of the imaged reflectors caused by the mineralization. Furthermore, the images show a reflector, which is interpreted to be a fault intersecting the mineralisation and which can be linked to the surface geology. The depth imaging results can serve as the basis for further investigations, drillings and follow-up mine planning at the Blötberget mining site.

中文翻译：

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使用聚焦叠前深度偏移方法对 Ludvika 矿区（瑞典）的氧化铁矿床进行 3D 反射地震成像

摘要。我们展示了位于瑞典中部 Bergslagen 矿区的 Blötberget 氧化铁矿场的 3D 反射地震勘探案例研究的叠前深度成像结果。本案例研究的目标是直接对含矿单元进行成像，并将其可能延伸到比现有钻孔已知的更深的位置进行绘制。因此，我们应用了定制的预处理工作流程以及两种不同的地震成像方法，即基尔霍夫叠前深度偏移和菲涅耳体积偏移 (FVM)。两种成像技术都能提供分辨率良好的矿床及其主岩的 3D 图像，其中 FVM 图像与 KPSDM 图像相比产生了明显更好的图像质量。我们能够解开不同的反射视野，它们与已知的矿化有关，并提供有关超出其已知延伸范围的钻孔数据的沉积物横向和深度范围的见解。已知矿化和图像的比较表明，由矿化引起的成像反射器的位置和形状非常吻合。此外，图像显示了一个反射器，它被解释为与矿化相交的断层，并且可以与地表地质有关。深度成像结果可作为 Blötberget 矿场进一步调查、钻探和后续矿山规划的基础。已知矿化和图像的比较表明，由矿化引起的成像反射器的位置和形状非常吻合。此外，图像显示了一个反射器，它被解释为与矿化相交的断层，并且可以与地表地质有关。深度成像结果可作为 Blötberget 矿场进一步调查、钻探和后续矿山规划的基础。已知矿化和图像的比较表明，由矿化引起的成像反射器的位置和形状非常吻合。此外，图像显示了一个反射器，它被解释为与矿化相交的断层，并且可以与地表地质有关。深度成像结果可作为 Blötberget 矿场进一步调查、钻探和后续矿山规划的基础。