Reaction Rates in Chemically Heterogeneous Rock: Coupled Impact of Structure and Flow Properties Studied by X-ray Microtomography

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Title: Reaction Rates in Chemically Heterogeneous Rock: Coupled Impact of Structure and Flow Properties Studied by X-ray Microtomography
Authors: Al-Khulaifi, Y
Lin, Q
Blunt, MJ
Bijeljic, B
Item Type: Journal Article
Abstract: We study dissolution in a chemically heterogeneous medium consisting of two minerals with contrasting initial structure and transport properties. We perform a reactive transport experiment using CO2-saturated brine at reservoir conditions in a millimeter-scale composite core composed of Silurian dolomite and Ketton limestone (calcite) arranged in series. We repeatedly image the composite core using X-ray microtomography (XMT) and collect effluent to assess the individual mineral dissolution. The mineral dissolution from image analysis was comparable to that measured from effluent analysis using inductively coupled plasma mass spectrometry (ICP-MS). We find that the ratio of the effective reaction rate of calcite to that of dolomite decreases with time, indicating the influence of dynamic transport effects originating from changes in pore structure coupled with differences in intrinsic reaction rates. Moreover, evolving flow and transport heterogeneity in the initially heterogeneous dolomite is a key determinant in producing a two-stage dissolution in the calcite. The first stage is characterized by a uniform dissolution of the pore space, while the second stage follows a single-channel growth regime. This implies that spatial memory effects in the medium with a heterogeneous flow characteristic (dolomite) can change the dissolution patterns in the medium with a homogeneous flow characteristic (calcite).
Issue Date: 13-Mar-2017
Date of Acceptance: 13-Mar-2017
URI: http://hdl.handle.net/10044/1/48092
DOI: https://dx.doi.org/10.1021/acs.est.6b06224
ISSN: 0013-936X
Publisher: American Chemical Society
Start Page: 4108
End Page: 4116
Journal / Book Title: ENVIRONMENTAL SCIENCE & TECHNOLOGY
Volume: 51
Issue: 7
Copyright Statement: © 2017 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
Sponsor/Funder: Qatar Shell Research and Technology Center QSTP LLC
Qatar Petroleum
Funder's Grant Number: 490000724
N/A
Keywords: Science & Technology
Technology
Life Sciences & Biomedicine
Engineering, Environmental
Environmental Sciences
Engineering
Environmental Sciences & Ecology
MINERAL DISSOLUTION RATES
POROUS-MEDIA
WORMHOLE FORMATION
CO2-INDUCED DISSOLUTION
CARBONATE ROCKS
PORE STRUCTURE
SURFACE-AREA
TRANSPORT
PERMEABILITY
SIMULATION
MD Multidisciplinary
Publication Status: Published
Open Access location: http://dx.doi.org/10.1021/acs.est.6b06224
Appears in Collections:Faculty of Engineering
Earth Science and Engineering



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