Beijing Key Laboratory of CO2 Utilization and Reduction Technology, Department of Thermal Engineering, Tsinghua University , Beijing, China.
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University , Beijing, China.
Environ Sci Technol. 2017 Aug 1;51(15):8869-8876. doi: 10.1021/acs.est.7b02493. Epub 2017 Jul 20.
CO sequestration in saline aquifers is a promising way to address climate change. However, the pressure of the sequestration reservoir may decrease in practice, which induces CO exsolution and expansion in the reservoir. In this study, we conducted a core-scale experimental investigation on the depressurization of CO-containing sandstone using NMR equipment. Three different series of experiments were designed to investigate the influence of the depressurization rate and the initial CO2 states on the dynamics of different trapping mechanisms. The pressure range of the depressurization was from 10.5 to 4.0 MPa, which covered the supercritical and gaseous states of the CO (named as CO(sc) and CO(g), respectively). It was found that when the aqueous phase saturated initially, the exsolution behavior strongly depended on the depressurization rate. When the CO and aqueous phase coexisting initially, the expansion of the CO(sc/g) contributed to the incremental CO saturation in the core only when the CO occurred as residually trapped. It indicates that the reservoir depressurization has the possibility to convert the solubility trapping to the residual trapping phase, and/or convert the residual trapping to mobile CO.
在盐水含水层中进行 CO 捕集是应对气候变化的一种很有前途的方法。然而，在实际应用中，封存库的压力可能会降低，从而导致 CO 在库中发生离解和膨胀。在这项研究中，我们使用 NMR 设备对含 CO 的砂岩进行了降压的岩心尺度实验研究。设计了三组不同的实验，以研究降压速率和初始 CO2 状态对不同捕集机制动力学的影响。降压压力范围为 10.5-4.0 MPa，涵盖了 CO 的超临界和气体状态（分别命名为 CO(sc)和 CO(g)）。结果表明，当初始时水相饱和时，离解行为强烈依赖于降压速率。当 CO 和水相共存时，只有当 CO 以残余捕获形式存在时，CO(sc/g)的膨胀才会导致岩心中 CO 饱和度的增量。这表明储层降压有可能将溶解捕获转化为残余捕获相，和/或将残余捕获转化为可动 CO。
