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碳捕获和地质储存是抑制大气中CO2含量增加的潜在途径。了解断层的作用,无论是作为CO2流动的障碍体还是通道,都是预测长期地质储存场地完整性的关键。特别值得关注的是地球化学反应对断层密封性的影响和地震活动及应力状态对断层稳定性的影响。本文研究了CO2从犹他州一个断裂的天然CO2气藏渗漏135 000年的古记录,测定了由富CO2流体沉淀形成的碳酸盐岩脉的U-Th年龄及其同位素和微量元素的组成。该岩脉地球化学特征随时间的变化表明,CO2从更深的地层脉冲式注入到储集层。这些气体脉冲式注入之后,CO2地面渗漏率增加几个数量级。我们说明,每次脉冲式注入发生在冰期向间冰期过渡期,当地气候开始变暖之后100~2 000年。CO2渗漏率增大是断裂开放的结果,断裂开放可归因于水文地质状况的变化、游离气顶的间歇性存在或者断裂附近地区地壳后冰川期的卸载作用。
Carbon capture and geological storage are potential ways to suppress the increase of atmospheric CO2. Understanding the role of faults, whether as an obstacle to or passage of CO2, is the key to predicting the integrity of long-term geological storage sites. Of particular concern are the effects of geochemical reactions on fault sealing and the effect of seismic and stress conditions on the fault stability. In this paper, CO2 depleted 135,000 years of paleo-CO2 records from a fractured natural CO2 reservoir in Utah and determined the U-Th ages and isotopic and trace elemental composition of carbonate veins formed by CO2-rich fluid sedimentation . The geochemical characteristics of the dikes over time indicate that CO2 is implanted pulsed into the reservoir from deeper formations. After these gases were implanted pulsed, the CO 2 ground leakage increased by several orders of magnitude. We show that each pulse injection takes place between the glacial-to-inter-glacial transition and 100-2000 years after the local climate begins to warm. The increase of CO2 leakage rate is the result of fracture opening. The open fracture can be attributed to the change of hydrogeological conditions, the intermittent presence of free gas domes or the unloading of the crust and post-crust glaciation.