Abstract Production from the Ekofisk Chalk Field in the North Sea is believed to be significantly influenced by the presence of a connected fault and fracture network. In the current study, we create a 3D seismic discontinuity cube which is representative of this network within the southern part of the Ekofisk Field. This is done using a multiscale workflow which integrates seismic fault and fracture detection with borehole image log interpretation from three horizontal well sections. The results show that faults and fractures are prevalent in the Ekofisk Formations. Within the study area, faults are mainly organised in three orientations: 1) WNW-ESE, 2) NNE-SSW and 3) NNW-SSE. Smaller E-W striking faults are also observed. The interpreted fractures show a similar pattern and are organized in four orientation groups: NW-SE, WNW-ESE, ENE-WSW and NE-SW. The analysis of seismic discontinuity data (i.e. faults and fractures detectable on seismic) indicates that most small-scale discontinuities occur in proximity to large faults, and that the Lower Ekofisk Formation is characterized by more widespread – and a higher intensity of small-scale seismic discontinuities. It is also demonstrated that along each studied well section, the extracted seismic discontinuities show a qualitative correlation with the image log interpretation. This correlation suggests that the 3D seismic discontinuity cube can serve as a proxy for the fault and fracture network in the southern part of the Ekofisk Chalk Field. Following from our key findings, we conclude that the presented workflow and results could provide a starting point for future studies assessing the impact of natural fractures in the Ekofisk – and other complex reservoirs.

中文翻译：

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Ekofisk 油田南部天然断层和裂缝网络特征：地震属性分析与图像测井解释相结合的案例研究

摘要 据信，北海 Ekofisk 白垩油田的生产受到连接断层和裂缝网络的显着影响。在当前的研究中，我们创建了一个 3D 地震不连续立方体，它代表了 Ekofisk 油田南部的这个网络。这是使用多尺度工作流完成的，该工作流将地震断层和裂缝检测与来自三个水平井段的钻孔图像测井解释相结合。结果表明，Ekofisk 地层中普遍存在断层和裂缝。在研究区内，断层主要以三个方向组织：1）WNW-ESE，2）NNE-SSW和3）NNW-SSE。还观察到较小的 EW 撞击断层。解释的裂缝显示出类似的模式，并分为四个方向组：NW-SE、WNW-ESE、ENE-WSW 和 NE-SW。对地震不连续性数据（即地震可检测到的断层和裂缝）的分析表明，大多数小规模不连续性发生在大断层附近，并且下 Ekofisk 组的特点是更广泛——小规模地震的强度更高不连续性。还证明了沿着每个研究的井段，提取的地震不连续性显示出与图像测井解释的定性相关性。这种相关性表明 3D 地震不连续立方体可以作为 Ekofisk Chalk Field 南部断层和裂缝网络的代表。根据我们的主要发现，