On the role of caprock and fracture zones in dispersing gas plumes in the subsurface,

Woods, A. W. and Norris, S. (2010) On the role of caprock and fracture zones in dispersing gas plumes in the subsurface,. Water Resources Research, 46. W08522. DOI 10.1029/2008WR007568

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Abstract

Waste stored in a geological disposal facility can generate gas, and depending on the geological environment, this gas may migrate into the rock mass. Here we develop a simplified physical model to describe the initial stages of the dispersal of a gas plume as it rises from such a geological disposal facility, located at a depth of many hundreds of meters below the surface. Typically, the plume becomes confined below a low-permeability layer and then spreads laterally until reaching a fault or fracture zone, when it may continue rising upward. Since the gas is soluble in the groundwater, the gas may partially dissolve as it displaces the groundwater. In addition, in the generic geology considered herein, since the source of gas gradually wanes with time, the spreading plume tends to thin out, leading to some residual trapping of the gas behind the plume. We show that depending on the distance of the fault or fracture zone from the geological disposal facility, different fractions of the source gas may be diverted farther upward into the formation rather than being trapped in the original layer. This can have an important impact on the subsequent pattern of dispersal of the gas by the groundwater flows, which may be key information in any safety assessment.

Item Type: Article
Uncontrolled Keywords: 2010AREP; IA61; BPI,
Subjects: 99 - Other
02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Water Resources Research
Volume: 46
Page Range: W08522
Identification Number: 10.1029/2008WR007568
Depositing User: Sarah Humbert
Date Deposited: 19 Jul 2010 09:46
Last Modified: 23 Jul 2013 09:57
URI: http://eprints.esc.cam.ac.uk/id/eprint/1464

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