Organic-rich mudstone successions are known to have significant vertical and lateral heterogeneity. This has been well documented in literature at the core scale and the basin scale in many unconventional reservoirs around the world. Investigating geological heterogeneity at the km-to sub-km scale is not always possible because of the dense well coverage necessary for such assessment. Therefore, facies heterogeneity assessment of organic-rich mudstones at the km-scale of investigation is poorly accounted for in literature. Using a case study from the Devonian Duvernay Formation of Western Canada, this study takes advantage of the large amount of well data available in the public domain to perform a heterogeneity assessment of organic-rich mudstone successions at the km-resolution. The five key petrofacies identified through core-to-well log tie – a) organic rich black siliceous mudstones, b) carbonate-rich mudstones, wackestones, and packstones, c) organic-poor clay-rich mudstones, d) organic-rich clay-rich mudstones, and e) interbedded silica-rich and carbonate-rich – were displayed in cross-sections and mapped across the study area for assessment of vertical and lateral heterogeneity. Analysis reveals that the Duvernay Formation has a significant degree of vertical and lateral heterogeneity, which varies depending on the location with respect to the main sediment sources active at the time of Duvernay deposition. These include debris flow channels originating from carbonate reefs, carbonate platforms in the NE that prograded westward towards the study area, and ocean currents that transported detrital clays into the area. In the upper Duvernay Member, parasequences of shallowing upward petrofacies can be correlated across the study area. However, these are locally interrupted by carbonate- or clay-rich petrofacies that comprise a significant part of the succession decreasing the thickness of the organic-rich petrofacies. Our analysis confirms that the Duvernay Formation shows significant lateral changes in occurrence and thickness of petrofacies at the sub-km scale, making it an extremely heterogeneous reservoir. This understanding may be applied to other shale plays worldwide which lack the well control necessary to perform a similar assessment.

已知富含有机质泥岩序列具有显着的垂直和横向非均质性。这在世界各地许多非常规油藏的核心尺度和盆地尺度的文献中都有很好的记载。由于此类评估需要密集的井覆盖，因此在公里到亚公里范围内调查地质非均质性并不总是可行的。因此，在研究的公里尺度上对富含有机质泥岩的相非均质性评估在文献中的解释很少。本研究使用加拿大西部泥盆纪 Duvernay 组的案例研究，利用公共领域中可用的大量井数据，以公里分辨率对富含有机质泥岩层序进行非均质性评估。通过岩心与井间测井关系确定的五个关键岩相 - a) 富含有机质的黑色硅质泥岩，b) 富含碳酸盐的泥岩、泥岩和泥灰岩，c) 富含有机质的富含粘土的泥岩，d) 富含有机质的粘土- 富泥岩，以及 e) 富含二氧化硅和富含碳酸盐的互层——显示在横截面中，并在整个研究区域绘制地图，以评估垂直和横向的非均质性。分析表明，Duvernay 组具有显着程度的垂直和横向非均质性，这取决于 Duvernay 沉积时活跃的主要沉积物来源的位置。其中包括源自碳酸盐岩礁的泥石流通道、向西向研究区进发的东北碳酸盐台地，以及将碎屑粘土输送到该地区的洋流。在上 Duvernay 段，浅层向上岩相的准层序可以在整个研究区域相关联。然而，这些被富含碳酸盐或粘土的岩相局部打断，这些岩相构成了层序的重要部分，降低了富含有机物的岩相的厚度。我们的分析证实，Duvernay 组在亚公里尺度上显示出显着的岩相产状和厚度横向变化，使其成为一个极其非均质的储层。这种理解可能适用于世界范围内缺乏进行类似评估所需的井控的其他页岩油田。这些被富含碳酸盐或粘土的岩相局部打断，这些岩相构成了层序的重要部分，降低了富含有机物的岩相的厚度。我们的分析证实，Duvernay 组在亚公里尺度上显示出显着的岩相产状和厚度横向变化，使其成为一个极其非均质的储层。这种理解可能适用于世界范围内缺乏进行类似评估所需的井控的其他页岩油田。这些被富含碳酸盐或粘土的岩相局部打断，这些岩相构成了层序的重要部分，降低了富含有机物的岩相的厚度。我们的分析证实，Duvernay 组在亚公里尺度上显示出显着的岩相产状和厚度横向变化，使其成为一个极其非均质的储层。这种理解可能适用于世界范围内缺乏进行类似评估所需的井控的其他页岩油田。