This study proposed and examined a practical technique for analysing CO₂ storage responses using offshore pressure transients affected by the ocean tide. The gravitational attractions of the solar-system bodies cause ocean tides, and the pore pressure exhibits diurnal and semidiurnal fluctuations in response to such tidal phenomena. The pressure-fluctuation amplitude is related to the loading efficiency, which is a function of reservoir elastic properties and fluid saturations. Therefore, the loading efficiency can be used to estimate the in situ pore compressibility and the CO₂ saturation. Applying the tidal-signal analysis in a time-lapse manner, one may see temporal changes in CO₂ saturation and consequently describe the dynamic behavior of sequestered CO₂. In the analysis at the offshore CO₂ storage site in Tomakomai, Japan, a temporal decrease in CO₂ saturation was detected during the shut-in period, which is caused primarily by CO₂ migration away from the well. The proposed methodology essentially requires only continuous pressure data, which are routinely available during CO₂ storage operations, and thus, can be a cost-effective and labour-saving monitoring technique.

这项研究提出并检验了一种实用技术，该技术可以利用受海潮影响的海上压力瞬变来分析CO _2的储存响应。太阳系物体的引力吸引引起海洋潮汐，并且响应于这种潮汐现象，孔隙压力表现出昼夜和半昼间的波动。压力波动幅度与加载效率有关，加载效率是储层弹性和流体饱和度的函数。因此，加载效率可用于估计原位孔隙可压缩性和CO ₂饱和度。以延时方式应用潮汐信号分析，可能会看到CO _2的时间变化饱和，因此描述了隔离的CO ₂的动态行为。在日本Tom小牧的海上CO ₂储存地点进行的分析中，在关闭期间检测到了CO ₂饱和度随时间的下降，这主要是由于CO ₂从井中迁移出来所致。所提出的方法基本上仅需要连续的压力数据，该数据通常在CO ₂储存操作期间可用，因此可以是一种经济高效且节省劳力的监测技术。