Experimental investigation into the sealing capability of naturally fractured shale caprocks to supercritical carbon dioxide flow
Experimental investigation into the sealing capability of naturally fractured shale caprocks to supercritical carbon dioxide flow
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DOI：
10.1007/s12665-013-2407-y
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发表时间：
2013-12-01
影响因子：
2.8
通讯作者：
McDermott, C. I.
中科院分区：
文献类型：
--
作者：
Edlmann, K.;Haszeldine, S.;McDermott, C. I.
CO2的地质储存被认为是减少释放到大气中的过量CO2的解决方案。低渗透性盖层物理地捕获注入到下伏多孔储层中的CO2。注入导致孔隙压力增加和有效应力降低，增加了超过盖层毛细管进入压力和盖层破裂的可能性。评价不同相态CO2在盖层基质和裂缝中的流动规律对评价CO2储集安全性具有重要意义。裂缝被认为是代表在盖层中的CO2逃逸的优先流动路径。在这里，我们提出了一个新的实验装置，允许38毫米直径的裂缝盖层样品从深度达4公里，暴露于超临界CO2（scCO（2））在原位条件下的压力，温度和地球化学。与预期相反，结果表明scCO（2）不会流过致密的天然盖层裂缝，即使压裂样品的压差超过51 MPa。然而，在CO2进入其气相的临界点以下，CO2容易流过盖层裂缝。这表明裂缝孔径大小的临界阈值的可能性，其控制CO2沿裂缝沿着流动。
Geological storage of CO2 is considered a solution for reducing the excess CO2 released into the atmosphere. Low permeability caprocks physically trap CO2 injected into underlying porous reservoirs. Injection leads to increasing pore pressure and reduced effective stress, increasing the likelihood of exceeding the capillary entry pressure of the caprocks and of caprock fracturing. Assessing on how the different phases of CO2 flow through caprock matrix and fractures is important for assessing CO2 storage security. Fractures are considered to represent preferential flow paths in the caprock for the escape of CO2. Here we present a new experimental rig which allows 38 mm diameter fractured caprock samples recovered from depths of up to 4 km to be exposed to supercritical CO2 (scCO(2)) under in situ conditions of pressure, temperature and geochemistry. In contrast to expectations, the results indicate that scCO(2) will not flow through tight natural caprock fractures, even with a differential pressure across the fractured sample in excess of 51 MPa. However, below the critical point where CO2 enters its gas phase, the CO2 flows readily through the caprock fractures. This indicates the possibility of a critical threshold of fracture aperture size which controls CO2 flow along the fracture.