The results of monitoring of carbon dioxide (⁠CO2⁠) injection at the Illinois Basin—Decatur Project (IBDP) and the companion Illinois Industrial Carbon Capture and Sequestration Sources (IL‐ICCS) project—have shown that reservoir response to fluid pressure changes can vary significantly at different injection locations within the same reservoir. Predrill reservoir characterization is important to identify potentially seismogenic faults. However, interpretations of newly reprocessed 3D seismic reflection data illustrate the challenges related to their identification in a region dominated by faulting with small vertical offsets. Faults interpreted in the 3D seismic volume range from ∼300 to 1200 m wide and are in the same size range as faults that could have been the source of historical events up to Mw 2.7 in central Illinois. The array of monitoring sensors that was installed for the IBDP continues to collect data, as injection operates in IL‐ICCS, the second injection well. CO2 injection rates for the IL‐ICCS well are on average 1.7 times the rates injected in the IBDP well, but a significantly reduced rate of induced seismicity is observed. This article presents results of passive seismic monitoring for the duration of the project to date, integrating active and passive seismic data to develop a new interpretation of the subsurface structure at the Decatur site that explicitly identifies pathways for fluid flow into the basement leading to induced seismicity, and provides a geological explanation for the sharp reduction of induced seismicity during injection at higher rates into the second well. The use of seismic moment to estimate the length of seismogenic slip planes in the local subsurface suggests that faults large enough to produce felt seismicity are unlikely to be present at or near the Decatur site.

中文翻译：

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伊利诺伊州盆地微震分析和断层再激活大小分析，以评估注入二氧化碳的毛毡事件的可能性

在伊利诺伊盆地迪凯特项目（IBDP）和相伴的伊利诺伊州工业碳捕集与封存源（IL-ICCS）项目中监测二氧化碳（⁠CO2⁠）注入的结果表明，储层对流体压力变化的响应可以同一油藏内不同注入位置的油井变化很大。预钻储层表征对于识别潜在的地震成因断层很重要。但是，对新近处理过的3D地震反射数据的解释说明了在以小垂直偏移断层为主的区域中与它们的识别有关的挑战。在3D地震体中解释的断层范围从〜300到1200 m宽，并且与可能是伊利诺伊州中部Mw 2.7的历史事件源的断层具有相同的大小范围。当注入在第二个注入井IL-ICCS中进行时，为IBDP安装的监视传感器阵列将继续收集数据。IL-ICCS井的CO2注入速率平均是IBDP井中CO2注入速率的1.7倍，但观察到的诱发地震活动率显着降低。本文介绍了迄今为止该项目期间的被动地震监测结果，整合了主动和被动地震数据，以对Decatur场地的地下结构进行新的解释，从而明确识别出流体流入地下室的路径，从而导致了地震活动。 ，并提供了地质解释，说明了以较高的速率注入第二口井期间诱导地震活动的急剧减少。