Injection‐induced seismicity became an important issue over the past decade, and although much of the rise in seismicity is attributed to wastewater disposal, a growing number of cases have identified hydraulic fracturing (HF) as the cause. A recent study identified regions in Oklahoma where ≥75% of seismicity from 2010 to 2016 correlated with nearly 300 HF wells. To identify factors associated with increased probability of induced seismicity, we gathered publicly available information about the HF operations in these regions including: injected volume, number of wells on a pad, injected fluid (gel vs. slickwater), vertical depth of the well, proximity of the well to basement rock, and the formation into which the injection occurred. To determine the statistical strength of the trends, we applied logistic regression, bootstrapping, and odds ratios. We see no trend with total injected volume in our Oklahoma dataset, in contrast to strong trends observed in Alberta and Texas, but we note those regions have many more multiwell pads leading to larger cumulative volumes within a localized area. We found a ∼50% lower probability of seismicity with the use of gel compared to slickwater. We found that HF wells targeting older formations had a higher probability of seismicity; however, these wells also tend to be deeper, and we found the trend with well depth to be stronger than the trend with age of formation. When isolated to the Woodford formation, well depth produced the strongest relationship, increasing from ∼5% to ∼50% probability from 1.5 to 5.5 km. However, no trend was seen in the proximity to basement parameter. Based on previously measured pore pressure gradients, we interpret the strong absolute depth relationship to be a result of the increasing formation overpressure measured in deeper portions of the basin that lower the stress change needed to induce seismicity.

中文翻译：

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影响俄克拉何马州水力压裂诱发地震可能性的因素

在过去的十年中，注入引起的地震活动成为一个重要的问题，尽管地震活动的增加大部分归因于废水处理，但越来越多的案例将水力压裂（HF）识别为原因。最近的一项研究确定了俄克拉荷马州从2010年至2016年地震≥75％的地区与近300口HF井相关的地区。为了确定与引起地震活动的可能性增加相关的因素，我们收集了有关这些地区HF操作的公开信息，包括：注入量，垫板上的井数，注入的流体（凝胶与滑水），井的垂直深度，井与基底岩石的距离以及注入的地层。为了确定趋势的统计强度，我们应用了逻辑回归，自举和比值比。与在艾伯塔省和德克萨斯州观察到的强劲趋势相反，我们在俄克拉荷马州数据集中没有看到总注入量的趋势，但我们注意到这些地区有更多的多孔板，导致局部区域内的累积量更大。我们发现，与滑水相比，使用凝胶的地震发生概率降低约50％。我们发现，针对较老地层的HF井具有较高的地震活动可能性。但是，这些井也往往更深，我们发现井深的趋势要强于地层年龄的趋势。当隔离到伍德福德地层时，井深产生了最强的关系，从1.5 km到5.5 km从5％到50％的概率增加。然而，在地下室参数附近没有发现趋势。根据先前测得的孔隙压力梯度，