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| Titel |
Can we get a better knowledge on dissolution processes in chalk by using microfluidic chips? |
| VerfasserIn |
Amélie Neuville, Mona Minde, Louis Renaud, Jan Ludvig Vinningland, Dag Kristian Dysthe, Aksel Hiorth |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151411
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| Publikation (Nr.) |
 EGU/EGU2017-15991.pdf |
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| Zusammenfassung |
| This work has been initiated in the context of research on improving the oil recovery in chalk
bedrocks. One of the methods to improve the oil recovery is to inject "smart water" (acidic
water/brines). Experiments on core scale and field tests that have been carried out the
last decade have clearly shown that water chemistry affects the final oil recovery.
However, there is generally no consensus in the scientific community of why additional
oil is released, and it is also still not understood what are the mineralogical and
structural changes. Direct in situ observation of the structural changes that occur
when chalk is flooded with brines could resolve many of the open questions that
remain.
One of the highlights of this work is thus the development of an innovative methodology
where fluid/rock interactions are observed in-situ by microscopy. To do so, we create several
types of custom-made microfluidic systems that embeds reactive materials like
chalk and calcite. The methodology we develop can be applied to other reactive
materials.
We will present an experiment where a calcite window dissolves with a fluid, where we
observe in-situ the topography features of the calcite window, as well as the dissolution rate
[1]. The injected fluid circulates at controlled flowrates in a channel which is obtained by
xurography: double sided tape is cut out with a cutter plotter and placed between the
reactive window and a non-reactive support. While the calcite window reacts, its
topography is measured in situ every 10 s using an interference microscope, with a
pixel resolution of 4.9 μm and a vertical resolution of 50 nm. These experiments
are also compared with reactive flow simulations done with Lattice Boltzmann
methods.
Then, we will present a dissolution experiment done with a microfluidic system that
embeds chalk. In this experiment, the main flow takes place at the chalk surface, in contact
with fluid flowing in a channel above the chalk sample. Thus the reaction mostly occurs at the
surface of the sample. The reacting chalk surface is observed in situ by stereomicroscopy and
by interferometry. The dissolution velocities are highly heterogeneous. To identify
the mineral change of the surface, a posteriori measurements using field emission
scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy
(EDS).
[1] Neuville et al, 2016, Xurography for microfluidics on a reactive solid, Lab on Chip,
DOI: 10.1039/c6lc01253a |
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