2. CO2 enhancing oil recovery
https://www.youtube.com/watch?v=NMBhX1IxajU
Permanent carbon capture
Miscibility of CO2 determines the efficiency
Background
4. Quantify the minimum miscibility pressure of CO2 in
crude oils
Verify the microfluidic MMP is able to reproduce the
literature values generated from RBA (Rising Bubble
Apparatus)
Objective
5. The lowest pressure for a gas to develop miscibility by multiple contact
process with oil at a fixed temperature.
At minimum miscibility pressure, the interfacial tension is zero and no
interface exists between the fluids.
Minimum miscibility pressure (MMP)
P< MMP P= MMP
Nguyen et. al. Anal. Chem. 2015
6. A current method used to measure
MMP
Similar methods: slim-tube test;
vanishing interfacial tension
method
Rising Bubble Apparatus (RBA)
Nguyen et. al. Anal. Chem. 2015
7. Conventional Methods vs. Microfluidic MMP
Long measurement time:
days/weeks
Short measurement time:
less than 30 min
(single pressure value: ~1 min;
a pressure range scan: 5-10 min)
Operator-dependent Operator-independent
Small sample volumes;
Rapid diffusive gas transport
Nguyen et. al. Anal. Chem. 2015
8. Silicon-glass chips with high tolerance
of T and P
p </= 40 Mpa, T</= 200 °C (± 1°C)
Fluorescent microscope to image
bubble formation
100 frame/second
Fast Fluorescence-based Microfluidic Method
Nguyen et. al. Anal. Chem. 2015
Nguyen et. al. Anal. Chem. 2015
10. Oil filled in main channel with a set pressure
CO2 injected with increasing pressure
Fluorescent dye and inherent
fluorescence present in oil
Fluorescent microscope monitoring at T
junction and downstream
Measurement
Nguyen et. al. Anal. Chem. 2015
11. Experimental Results I
a) Fluorescence imaging of CO2 bubbles
b) Comparing between microfluidic MMP
measurements and literature values from
RBA
c) Linear dependence of MMP on
temperature for synthetic oils
hexadecane/pentane, 63 to 79 API
(American Petroleum Institution) with decreasing in
density
12. Fluorescence images at 1.45 seconds
Variations in fluidic mixing indicate
difference in oil density/composition
Experimental Results II
MMP values increase with temperature and
density
Nguyen et. al. Anal. Chem. 2015
13. Detection plot over time
a) Below MMP:
○ CO2: Low intensity
○ Oil: high intensity
b) At MMP: intensity
stabilized
Experimental Results III
Nguyen et. al. Anal. Chem. 2015
14. Experimental Results IV
Nguyen et. al. Anal. Chem. 2015
c) Variation in
intensity over time at
different pressures
d) Plot of the greatest
slopes retrieved from
intensity curves
MMP=6.14
Mpa
Editor's Notes
the conventional methods take days or weeks to analyze one (oil) sample
because they require technicians to operate the instrument, insert samples, and analyze the data collected
for microfluidic method, it only takes 30 minutes to analyze one sample
they all have the benefit of using small sample volumes and the carbon dioxide can diffuse rapidly in the instruments.
before the measurements are taken,
first oil is filled in the main channel with a constant pressure
and then carbon dioxide is injected with an increasing pressure.
for synthetic oils, fluorescent dye is added
however for natural oils, they dont require fluorescent dye because
they already have compounds which can fluorescent
the microscopic camera is monitoring the region showing in this picture.
carbon dioxide comes and produces bubbles at the T junctions and its downstream,
thats why we take measurements in this region.
