高盐度卤水对CO_2地质封存的影响:以江汉盆地潜江凹陷为例

Effect of High Salinity on CO_2 Geological Storage:A Case Study of Qianjiang Depression in Jianghan Basin

江汉盆地潜江凹陷卤水资源十分丰富,潜江组泥膏岩、泥岩和砂岩交替沉积,构成CO2地质储存的潜在场所.但是潜江组卤水层矿化度非常高,平均值高达283.25g/L.以高盐度卤水为对象,探讨了高盐度卤水对CO2封存过程中产生的物理化学影响.结果表明,往高盐度卤水层中单纯地注入CO2会造成CO2溶解量和矿物捕集量的显著降低,不利于CO2的储存安全.高盐度会造成注入井附近发生盐岩大量沉淀,不利于CO2的持续注入,同时造成近井周围压力严重积累,降低了封闭安全系数.采用CO2与卤水联合注采模式,可有效缓解CO2单纯地注入过程中的压力严重积累和盐岩沉淀问题,实现资源和地下空间最大化利用,收获经济和环保的双重效益.

The brine resource in the Qianjiang depression in Jianghan basin is rich in the brine resource because alternating deposits of gypsum mudstone,mudstone as well as sandstone of Qianjiang Formation form the potential sites for CO2 geological storage.However,the salinity in Qianjiang Formation is very high with the average value up to 283.25 g/L.The purpose of this study is to investigate the physical and chemical responses under the condition of high salinity.The results show that the CO2 dissolved in brine and sequestered in minerals decline significantly as a result of directly injecting CO2 into the brine with high salinity,which may affect the storage safety.Moreover,high salinity will lead to serious salt precipitation around the injection well which may reduce the injectivity.High salinity can also cause the high pressure build up around the injection well.The method of CO2 injection combined with brine production can effectively mitigate the severe pressure build up and salt precipitation.In this way,we can maximize the utilization of brine resource and the underground space and achieve both the econimic benifits and the environmental benefits.