Abstract We used 2D and 3D electrical resistivity imaging (ERI) data inversion to locate and characterize the coal seams in Mmamabula Coalfield. The 2D ERI data inversion usually assumes that subsurface geological units (e.g. coal seams) are infinitely continuous in the direction perpendicular to the profiles. However, this assumption might be violated due to the heterogeneous nature of fluvial/deltaic environments. The lateral variation of the subsurface material can be effectively determined in 3D ERI inversion models. In this study, 2D ERI data were acquired along ten parallel profiles trending north-south, then inverted to produce 2D and 3D models. From the 2D ERI inversion results, we observed that the shallower coal seam occurs around a consistent depth of 13.6 m whereas the second observable coal seam occurs at variable depths including at 50 m and 60 m along the two profiles. Discontinuities in coal seams were also identified. However, the information provided by 2D data inversion in such an environment is insufficient to determine the geometry of coal seams as well as to produce accurate and precise resource estimates for future exploitation. As an alternative, 3D data inversion gives better insight on the subsurface geology complexity and significantly resolves the geometry of coal within the study area. The presented 3D inversion results indicate that coal seams are intermittent and alternate well with other coexisting sedimentary units. We also deduced that they trend east-west and are split and adjoined in some areas along the north-south direction. Overall, 3D data inversion result resolves the elongated coal seams in Mmamabula Coalfield and reveals additional information that cannot be determined on 2D ERI inversion results.

中文翻译：

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使用伪 3D 电阻率成像技术表征位于博茨瓦纳中部 Mmamabula 煤田的煤层

摘要 我们使用 2D 和 3D 电阻率成像 (ERI) 数据反演来定位和表征 Mmamabula 煤田的煤层。二维 ERI 数据反演通常假设地下地质单元（例如煤层）在垂直于剖面的方向上是无限连续的。然而，由于河流/三角洲环境的异质性，这个假设可能会被违反。地下物质的横向变化可以在 3D ERI 反演模型中有效地确定。在这项研究中，沿着南北走向的十个平行剖面获取二维 ERI 数据，然后反演以生成 2D 和 3D 模型。从二维 ERI 反演结果中，我们观察到较浅的煤层出现在一致的 13 深度附近。6 m，而第二个可观测煤层出现在沿两个剖面的不同深度，包括 50 m 和 60 m。还发现了煤层的不连续性。然而，在这种环境中二维数据反演提供的信息不足以确定煤层的几何形状以及为未来的开采提供准确和精确的资源估计。作为替代方案，3D 数据反演可以更好地了解地下地质复杂性，并显着解析研究区域内煤的几何形状。所呈现的 3D 反演结果表明，煤层是间歇性的，并且与其他共存沉积单元很好地交替。我们还推断出它们呈东西走向，并在沿南北方向的一些地区分裂和邻接。全面的，