Localized buoyant convection in porous media: plumes and dispersion

多孔介质中的局域浮力对流：羽流和弥散

• 批准号: RGPIN-2019-04581
• 负责人: Flynn, Morris
• 金额: $ 3.35万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=737714
• 关键词: Localized; buoyant; convection; porous; media

Examples of buoyancy-driven flow abound in nature, industry and everyday life from atmospheric convection to the steam that rises from a hot kettle on the stovetop. Less obvious, but equally important, is buoyancy-driven flow within a porous medium whereby hot/cold fluid navigates through the interstitial spaces between solid grains. Indeed, buoyant convection within porous media is relevant to energy systems e.g. thermal energy storage, methods of enhanced oil recovery such as steam-assisted gravity drainage or cyclic steam stimulation, and the geological sequestration of either carbon dioxide (CO2) or acid-gas (a mixture of CO2 and hydrogen sulfide), which result from the production of electricity and oil. The research proposed here, though fundamental in focus, is motivated most especially by this latter example. To this end, one must define the precise conditions under which the CO2 or acid-gas injected into formation will remain permanently sequestered. Although there are a variety of mechanisms that allow the injectate to become immobilized (capillary trapping, etc.), CO2 and acid-gas are more buoyant than, say, aquifer brine and tend therefore to rise from one geological layer to the next. The competition between immobilization and vertical migration, far from being of purely academic interest, determines whether the large outlays of public and private capital necessary for geological sequestration projects are, in fact, justified. In my research, I will use theory and laboratory experiment to advance our current understanding of buoyant convection in porous media. Three interconnected projects will be pursued. Firstly, I will consider the impingement of a buoyant plume on a sloping interface where the fluid has an easy and difficult time, respectively, flowing through the layers below and above. This mimics a scenario in which a plume of buoyant CO2 or acid-gas strikes a (possibly fractured) cap rock layer having a comparatively small permeability. To this base flow, and consistent with real geophysical scenarios, I will then allow some fraction of the injectate to dissolve into the ambient reservoir fluid. Although the volume of dissolving injectate is small, the impact on the flow dynamics is expected to be large. Finally, and again consistent with real flows, I will then specifically account for the limited miscibility of CO2 or acid-gas in aquifer brine. Doing so requires accounting for surface tension among other effects. Model predictions and measured data may be adapted into basin-scale geological algorithms that lack sufficient resolution to fully describe flow details at fine spatial scales. Instead, parameterizations of the tradeoffs between injectate drainage, advection and dissolution are required. To this end, a broader objective of the research is to collect, interpret and synthesize data in a way that is meaningful to other researchers, industry practitioners, regulators and policy makers.

浮力驱动的流动的示例在自然界，工业和日常生活中从大气连接到蒸汽从炉灶上的热水壶上升。不太明显但同样重要的是浮力驱动的流动介质中的流动流，从而使热/冷流体在固体晶粒之间的间隙空间导航。确实，多孔介质中的浮力连接与能源系统有关，例如热能储存，增强的油回收率的方法，例如蒸汽辅助的重力排水或环状蒸汽刺激，以及二氧化碳（CO2）或酸性气（CO2和硫化氢的混合物）的地质疗程，这是由电力和油的产生产生的。在此示例中，这里提出的研究虽然是基础，但尤其是最大的动机。为此，必须定义将二氧化碳或酸性气体注入地层的精确条件将保持永久性。尽管有多种机制可以使注射固定（毛细血管捕获等），但二氧化碳和酸性气是比含水层盐水更浮动的，因此倾向于从一个地质层上升到下一个地质层。实际上，固定和垂直迁移之间的竞争远非纯粹的学术利益，决定了地质会议项目所必需的庞大公共和私人资本支出是否是合理的。在我的研究中，我将使用理论和实验室实验来促进我们当前对多孔媒体浮力联系的理解。将追求三个相互联系的项目。首先，我将考虑在倾斜的界面上撞击浮力的羽流，该接线界分别具有轻松且困难的时期，流过下方和更高上方的层。这模仿了一种场景，其中浮力二氧化碳或酸性气体撞击了（可能碎片的）盖岩层层相对较小的渗透率。对于这种基本流量，与实际地球物理场景一致，然后我将允许注入的一小部分溶解到环境储液中。尽管溶解注射的体积很小，但对流动动力学的影响预计很大。最后，我将再次与真实的流相一致，然后我将专门考虑含水层盐水中二氧化碳或酸性气的有限混溶性。这样做需要考虑表面张力以及其他效果。模型预测和测量的数据可以适应盆地规模的地质算法，这些算法缺乏足够的分辨率来完全描述精细空间尺度上的流动细节。取而代之的是，需要在注入引流，对流和解散之间取舍的参数。为此，该研究的更广泛的目标是以对其他研究人员，行业从业人员，监管者和政策制定者有意义的方式收集，解释和综合数据。