Abstract. Between 1986 and 1995 429 hydrofracturing tests have been carried out in six, now abandoned, coal mines and two coal bed methane boreholes at depths between 600 and 1950 m within the greater Ruhr region in western Germany. From these tests, stress magnitudes and orientations of the stress tensor are derived. The majority of hydrofracturing tests were carried out from mine galleries away from mine workings in a relatively undisturbed rock mass. These data along with detailed information have been disclosed recently. In combination with already published material, we provide the first comprehensive stress database of the greater Ruhr region. Our study summarizes results of the extensive in situ stress test campaign and assigns quality to each data record using the established quality ranking schemes of the World Stress Map project. The stress magnitudes suggest predominantly strike-slip stress regime, where the magnitude of the minimum horizontal stress, S_hmin, is half of the magnitude of the maximum horizontal stress, S_Hmax, implying that the horizontal differential stress is high. We observe no particular change in the stress gradient at depth throughout the Carboniferous layers and no significant difference between tests carried out in coal mines and deep boreholes. The mean S_Hmax orientation varies between 133 ± 13° in the easternmost located Friedrich-Heinrich coal mine and 168 ± 23° in the westernmost located Westfalen coal mine. The mean S_Hmax orientation, based on 87 data records from this as well as already published studies, of 161 ± 43° is in good agreement with the regional stress orientation observed in Northwestern Europe. The presented public database provides in situ stress magnitude and stress orientation data records that are essential for the calibration of geomechanical numerical models on regional and/or reservoir scales for, among others, assessing stability issues of borehole trajectories, caverns, and georeservoirs in general. For an application example of this database, we estimate slip and dilation tendencies of major geological discontinuities, discovered during the 700-year-long coal mining activities in the region. The result shows that the discontinuities striking in the N-S and NW-SE directions have a higher slip tendency compared to the ones striking ENE-WSW and NNW-SSE, whereas a high dilation tendency is observed for discontinuities striking NNW-SSE and a low dilation tendency for the ones striking ENE-WSW.

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来自水力压裂试验和钻孔测井的大鲁尔区（德国）地应力数据库

摘要。1986 年至 1995 年间，在德国西部大鲁尔区 600 至 1950 米深度的 6 个现已废弃的煤矿和两个煤层气钻孔中进行了 429 次水力压裂试验。从这些测试中，可以得出应力张量的应力大小和方向。大多数水力压裂试验是在远离矿井的矿道中进行的，在相对未受干扰的岩体中进行。这些数据以及详细信息最近已被披露。结合已发表的材料，我们提供了大鲁尔区的第一个综合应力数据库。我们的研究总结了广泛的现场压力测试活动的结果，并使用世界压力地图项目的既定质量排名方案为每个数据记录分配质量。S _hmin是最大水平应力S _Hmax大小的一半，这意味着水平微分应力很高。我们观察到整个石炭纪地层深度处的应力梯度没有特别的变化，在煤矿和深钻孔中进行的测试之间没有显着差异。位于最东端的弗里德里希-海因里希煤矿的平均S _Hmax方向在 133 ± 13° 和位于最西端的威斯特法伦煤矿的 168 ± 23° 之间变化。平均S _Hmax161 ± 43° 的 161 ± 43° 的方向与在西北欧观察到的区域应力方向非常一致。所提供的公共数据库提供了原位应力大小和应力方向数据记录，这些记录对于校准区域和/或储层规模的地质力学数值模型至关重要，尤其是评估钻孔轨迹、洞穴和地质储层的稳定性问题。对于该数据库的一个应用示例，我们估计了在该地区 700 年的煤炭开采活动中发现的主要地质不连续性的滑动和扩张趋势。