Energy Geosciences Division, Earth and Environment Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720;
Energy Geosciences Division, Earth and Environment Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
Proc Natl Acad Sci U S A. 2018 Jan 30;115(5):873-878. doi: 10.1073/pnas.1710853114. Epub 2018 Jan 16.
Interactions between supercritical (sc) CO and minerals are important when CO is injected into geologic formations for storage and as working fluids for enhanced oil recovery, hydraulic fracturing, and geothermal energy extraction. It has previously been shown that at the elevated pressures and temperatures of the deep subsurface, scCO alters smectites (typical swelling phyllosilicates). However, less is known about the effects of scCO on nonswelling phyllosilicates (illite and muscovite), despite the fact that the latter are the dominant clay minerals in deep subsurface shales and mudstones. Our studies conducted by using single crystals, combining reaction (incubation with scCO), visualization [atomic force microscopy (AFM)], and quantifications (AFM, X-ray photoelectron spectroscopy, X-ray diffraction, and off-gassing measurements) revealed unexpectedly high CO uptake that far exceeded its macroscopic surface area. Results from different methods collectively suggest that CO partially entered the muscovite interlayers, although the pathways remain to be determined. We hypothesize that preferential dissolution at weaker surface defects and frayed edges allows CO to enter the interlayers under elevated pressure and temperature, rather than by diffusing solely from edges deeply into interlayers. This unexpected uptake of CO, can increase CO storage capacity by up to ∼30% relative to the capacity associated with residual trapping in a 0.2-porosity sandstone reservoir containing up to 18 mass % of illite/muscovite. This excess CO uptake constitutes a previously unrecognized potential trapping mechanism.
当 CO 被注入地质地层以进行储存或作为提高石油采收率、水力压裂和地热能提取的工作流体时，超临界 (sc) CO 与矿物之间的相互作用非常重要。以前已经表明，在深部地下的高压和高温条件下，scCO 会改变蒙脱石（典型的膨胀层状硅酸盐）。然而，尽管后者是深部地下页岩和泥岩中主要的粘土矿物，但对于 scCO 对非膨胀层状硅酸盐（伊利石和白云母）的影响知之甚少。我们通过使用单晶进行的研究，结合反应（与 scCO 孵育）、可视化（原子力显微镜 (AFM)）和定量分析（AFM、X 射线光电子能谱、X 射线衍射和放气测量），发现 CO 的吸收量出人意料地高，远远超过了其宏观表面积。来自不同方法的结果共同表明，CO 部分进入了白云母层间，尽管途径仍有待确定。我们假设，在较弱的表面缺陷和磨损边缘处的优先溶解允许 CO 在高压和高温下进入层间，而不是仅通过从边缘扩散到层间深处来实现。这种对 CO 的意外吸收可以将 CO 的储存容量提高高达约 30%，与在含有高达 18%质量分数的伊利石/白云母的 0.2 孔隙度砂岩储层中与残留捕获相关的容量相比。这种过量的 CO 吸收构成了以前未被认识到的潜在捕获机制。
