Dispersal of Buoyancy-Driven Flow in Porous Media with Inclined Baffles

Rayward-Smith, W. J. and Woods, Andrew W. (2011) Dispersal of Buoyancy-Driven Flow in Porous Media with Inclined Baffles. Journal of Fluid Mechanics, 689. pp. 517-528. DOI 10.1016/j.jsg.2012.01.009

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Abstract

Here we explore the effect of a series of low-permeability tilted baffles on the ascent of a buoyant fluid injected into a porous rock from a linear well, motivated by several industrial processes, particularly CO2 sequestration. We first consider, both theoretically and experimentally, the dynamics associated with flow past an individual inclined baffle; if the incident flux is sufficiently large then a pool of injectate grows beneath the baffle and spills over both ends, partitioning the flux, but otherwise the injectate only flows over the updip end of the baffle, leaving a stagnant zone under the downdip part of the baffle. In a multi-layered system, the flow may then be described using nonlinear recurrence relations based on the flow past an individual baffle. Using this approach, in the particular case in which there is a regular distribution of baffles, we show that, on a scale greater than individual baffles, the flow adjusts to a plume of constant width rising at an angle to the vertical, which depends on the geometry of the baffles. This constant-width plume may be described by an effective directional permeability at angles to the vertical where we find , where is the effective permeability of the regions between baffles. Within the boundaries of this plume the majority of pore space is bypassed. Indeed, the plume-scale effective porosity is largely associated with the pools of injectate which collect beneath each baffle. We show that since the constant-width plume has such a large lateral extent, the total pore space occupied by the plume, per unit height, is larger than for a homogeneous formation. Furthermore, these pools lead to a large surface area between injectate and formation water, which enhances the reaction of the injectate with the formation water. However, we also show that, in steady state, it may be hard to determine this plume-scale effective porosity since the ratio of the effective Darcy speed and the effective interstitial speed of the plume only relates to the porosity of the updip part of these pools, in which the injectate is flowing.

Item Type: Article
Uncontrolled Keywords: 2011AREP; IA63; BPI,
Subjects: 99 - Other
Divisions: 99 - Other
Journal or Publication Title: Journal of Fluid Mechanics
Volume: 689
Page Range: pp. 517-528
Identification Number: 10.1016/j.jsg.2012.01.009
Depositing User: Sarah Humbert
Date Deposited: 10 Mar 2012 12:34
Last Modified: 23 Jul 2013 10:03
URI: http://eprints.esc.cam.ac.uk/id/eprint/2402

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