Summary
A mathematical model is developed for performance prediction of
waterflooding performance in communicating stratified reservoirs with a dip
angle from the horizontal. The effect of the gravitational force is reflected
by a dimensionless gravity number in the fractional flow formula. The gravity
number accounts for the dip angle and the density difference between the
displacing and displaced fluids. The developed fractional flow formula is used
to estimate the fractional oil recovery, the dimensionless time, and the
injectivity ratio at times of water breakthrough in the successive layers. The
developed model allows for each layer to have its own porosity, endpoint
saturations, and endpoint relative permeabilities.
Solutions for the waterflooding performance in inclined communicating
stratified systems with log-normal permeability distribution were obtained and
compared with that of the horizontal systems. The effects of the gravity
number, the mobility ratio, and the Dykstra-Parsons permeability-variation
coefficient VDP on the performance were investigated.
The obtained results showed that the gravity effect of the dip angle
enhances the performance in terms of delayed water breakthrough, higher
fractional oil recovery, and lower water cut. This improved performance is more
significant in the cases of unfavorable mobility ratio and of highly
heterogeneous reservoirs. Reservoir dipping does not affect the pseudorelative
permeability functions but results in a decrease in the injectivity ratio.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
15 December 2009
- Meeting paper published:
15 February 2010
- Revised manuscript received:
5 November 2010
- Manuscript approved:
17 November 2010
- Published online:
9 August 2011
- Version of record:
13 March 2012
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