SPE Journal
Volume 17,
Number 1,
March 2012,
pp. 43-52
Summary
This work studies the mixing of injected water and in-situ water during
waterfloods and demonstrates that the mixing process is sensitive to the
initial water saturation. The results illustrate differences between a
waterflooded zone and a preflooded zone during, for example, water-based EOR
displacement processes. The mixing of in-situ, or connate, water and injected
water during laboratory waterfloods in a strongly water-wet chalk core sample
was determined at different initial water saturations. Dynamic 1D
fluid-saturation profiles were determined with nuclear-tracer imaging (NTI)
during waterfloods, distinguishing between the oil phase, connate water, and
injected water. The mixing of connate and injected water during waterfloods,
with the presence of an oil phase, resulted in a displacement of all connate
water from the core plug. During displacement, connate water banked in front of
the injecting water, separating (or partially separating) the injected water
from the mobile oil phase. This may impact the ability of chemicals dissolved
in the injected water to contact the oil during secondary recovery and EOR
processes. The effect of the connate-water-bank separation was sensitive to the
initial water saturation Swi ). The time difference between
breakthrough of connate water and breakthrough of injected water at the outlet
showed a linear correlation to the initial water saturation (Swi
). The results obtained in chalk confirmed earlier findings in
sandpacks (Brown 1957) and thus demonstrated the generality in the results.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
13 September 2010
- Revised manuscript received:
19 April 2011
- Manuscript approved:
28 April 2011
- Published online:
30 November 2011
- Version of record:
13 March 2012
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