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CO2 geological storage: Critical insights on plume dynamics and storage efficiency during long-term injection and post-injection periods
Gas Science and Engineering ( IF 5.285 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.jngse.2020.103542
Y. Zapata , M.R. Kristensen , N. Huerta , C. Brown , C.S. Kabir , Z. Reza

Abstract In the quest for net-zero greenhouse gas emission, CO2 capture and storage technologies play a prominent role. Estimates suggest a potential of sequestering up to several thousand metric gigatons of CO2. However, some of the main challenges in its development are an assessment of reservoir-specific storage capacities due to variabilities and heterogeneities in the underlying properties (structure, formations, facies, petrophysics, reservoir architecture, and others) and understanding the migration of CO2 in the subsurface. This article critically investigates CO2 plume characteristics and determines the evolving contributions of different trapping mechanisms during a 100-year injection and 200-year post-injection periods. CO2 can reside in various forms in saline aquifers. To account for these, we characterized CO2 plumes in multiple ways based on dissolved CO2 in the aqueous phase, free phase CO2, pH change, and finally, change in solid-phase saturation (due to precipitation and dissolution of salts and calcite). Based on how we define the plumes, the sizes, and the shapes of the plumes differ. Emphasis is on the characterization of the plume, its evolution, and the contributing trapping mechanisms. Additionally, we ascertain the impact of various uncertain variables, including heterogeneity and anisotropy in geological formation properties, reservoir-brine composition, and molecular diffusion on CO2 plume dynamics and storage via statistical Design of Experiments. Simulation results indicate that lateral propagation of the CO2 plume is much larger than vertical dispersion typically attributed to the presence of flow baffles and vertical stratification. The ratio of average lateral to vertical propagation ranged between 7 and 44. In general, various geometries and growth patterns evolved for the CO2 plume and are strongly influenced by the total amount of CO2 injected and the permeability directional anisotropies. On average, for all case scenarios investigated, free phase CO2 is the dominant trapping mechanism (in terms of the amount of CO2 stored) during the injection period, storing up to 60% of the CO2 injected. Both residual (20%) and solubility (16%) trapping storage ratios exhibited higher storage with time than structural trapping (10%). Effectively little mineral trapping transpires during the 100-year injection period. Another important observation is the fact that facies-dependency on saturation functions appears to have a substantial effect on different trapping mechanisms. Shale-dominant facies manifests more residual trapping than other facies.

中文翻译:

CO2 地质封存:关于长期注入和后注入期间羽流动力学和封存效率的重要见解

摘要 在追求温室气体净零排放的过程中,CO2 捕集和封存技术发挥着重要作用。估计表明有可能封存数千公吨的二氧化碳。然而,其开发中的一些主要挑战是由于潜在特性(结构、地层、相、岩石物理、储层结构等)的可变性和异质性而对储层特定存储容量的评估,以及了解 CO2 在储层中的迁移。次表面。本文批判性地研究了 CO2 羽流特征,并确定了 100 年注入和 200 年注入后不同捕获机制的演变贡献。CO2 可以以各种形式存在于咸水层中。考虑到这些,我们基于水相中溶解的 CO2、游离相 CO2、pH 变化以及最终固相饱和度的变化(由于盐和方解石的沉淀和溶解)以多种方式表征了 CO2 羽流。根据我们如何定义羽流,羽流的大小和形状有所不同。重点是羽流的特征、其演变和诱捕机制。此外,我们通过实验统计设计确定了各种不确定变量的影响,包括地质地层特性的异质性和各向异性、储层-盐水组成和分子扩散对 CO2 羽流动力学和储存的影响。模拟结果表明 CO2 羽流的横向传播远大于通常归因于流动挡板和垂直分层的垂直扩散。平均横向与垂直传播的比率在 7 到 44 之间。总的来说,CO2 羽流演化出各种几何形状和生长模式,并受到注入的 CO2 总量和渗透率方向各向异性的强烈影响。平均而言,对于所有调查的案例场景,自由相 CO2 是注入期间的主要捕集机制(就储存的 CO2 量而言),储存高达注入的 CO2 的 60%。残留 (20%) 和溶解度 (16%) 捕集存储率随时间显示出比结构捕集 (10%) 更高的存储。在 100 年的注入期内,几乎没有矿物捕集发生。另一个重要的观察结果是,相依赖于饱和函数似乎对不同的捕获机制有重大影响。页岩优势相比其他相表现出更多的残余圈闭。
更新日期:2020-11-01
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