Introduction: Carbon capture and storage (CCS) is important for achieving net-zero carbon emissions. However, although the current geological storage capacity stands at approximately 3,000 Gt-CO2, the formation pressure increases with CO2 injection, imposing severe constraints on capacity from a geomechanical perspective. This study numerically examined nine cases (combinations of three fracture pressures and three aquifer radius factors) through sensitivity analysis to quantify the effects of these parameters on CO2 injection mass and storage capacity.Methods: The CO2 injection mass was determined as the cumulative CO2 injected until the formation pressure reached a specified fracture pressure. Storage capacity was defined as the amount of CO2 enclosed within the reservoir based on a fill-and-spill analysis encompassing 200 years after the start of injection (2230).Results: Based on the sensitivity analysis, the aquifer radius had a greater impact on the CO2 injection mass and storage capacity than the fracture pressure. A sufficiently high aquifer radius factor can compensate for the capacity limitations imposed by a low fracture pressure. For the lowest fracture pressure (20.95 MPa), considering a safety factor of 0.8, the CO2 injection mass increased approximately 5.5 times, from 3.2 to 17.6 Mt-CO2, depending on the aquifer radius factor ranging from 2 to 7.Discussion: Therefore, geological sites with high aquifer radius factors and low fracture pressures were preferred over those with low aquifer radius factors and high fracture pressures. Nevertheless, when considering space-limited capacity, storage efficiency, defined as the ratio of injected to stored CO2, tends to be higher (approximately 80%) when both parameters are low. The scenario featuring the highest aquifer radius factor and fracture pressure reached an injection mass of 68.9 Mt-CO2. However, the storage efficiency was only 23% due to space constraints. This study provides key insights into two pivotal parameters from pressure- and space-limited perspectives, which must be collectively considered to reliably evaluate CCS projects.

中文翻译：

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含水层大小和地层破裂压力对 CO2 地质封存能力的影响

简介：碳捕获和封存（CCS）对于实现净零碳排放非常重要。然而，尽管目前的地质封存容量约为 3,000 Gt-CO2, 地层压力随 CO 的增加而增加2注入，从地质力学的角度来看，对容量施加了严格的限制。本研究通过敏感性分析对九个案例（三个破裂压力和三个含水层半径因素的组合）进行了数值研究，以量化这些参数对 CO 的影响2注入质量和储存容量。方法：CO2注入质量确定为累积 CO2注入直至地层压力达到规定的破裂压力。储存容量定义为 CO2 的量2根据注入开始后 200 年 (2230) 的填充和溢出分析，将其封闭在水库内。结果：根据敏感性分析，含水层半径对 CO 的影响更大2注入质量和储存能力大于破裂压力。足够高的含水层半径系数可以补偿低破裂压力造成的容量限制。对于最低破裂压力（20.95 MPa），考虑安全系数为 0.8，CO2注入质量增加了约 5.5 倍，从 3.2 Mt-CO 增加到 17.6 Mt-CO2，取决于含水层半径系数，范围为 2 至 7。讨论：因此，含水层半径系数高、破裂压力低的地质场地优于含水层半径系数低、破裂压力高的地质场地。然而，当考虑空间有限的容量时，储存效率定义为注入的二氧化碳与储存的二氧化碳的比率2，当两个参数都很低时，往往会更高（大约 80%）。该方案具有最高的含水层半径系数和破裂压力，注入质量达到 68.9 Mt-CO2。但由于空间限制，存储效率仅为23%。这项研究从压力和空间有限的角度提供了对两个关键参数的重要见解，必须共同考虑这些参数才能可靠地评估 CCS 项目。