Summary
The flow in regions of oil and gas reservoirs that are dominated by gravity
segregation can occur through two different mechanisms. First, all reservoir
fluid phases, possibly oil, gas and water, might move through the same pores.
One or more phases might move upward while the others move countercurrently
downward, in the same pores. If such a mechanism were valid, Darcy's law could
be applied uniformly over large areas of the reservoir to provide average-phase
velocities, just as if the flows were the result of pressure-induced
convection. However, a second mechanism is also possible. The phases might be
segregated such that some pores carry the upward flowing phases, while other
pores carry downward flows. When this mechanism is valid, Darcy's law applies
only locally to the upward or downward regions of flow.
The two mechanisms result in substantially different phase velocities.
Simulators, including those available commercially, generally assume the first
mechanism (i.e., uniform, countercurrent flow throughout each simulation cell).
This paper describes an experimental study in which two-phase flow velocities
were measured as the phases moved through a bed of small, uniform glass beads,
as the result of gravitational forces only. The resulting velocities were more
consistent with those predicted for segregated flows of Mechanism 2 compared
with those of the commonly assumed homogeneous flows of Mechanism 1. These
results suggest that greater accuracy in reservoir simulation may be achieved
by including segregated flow in areas of the reservoir where gravity
segregation predominates.
© 2010. Society of Petroleum Engineers
View full textPDF
(
985 KB
)
History
- Original manuscript received:
2 April 2009
- Meeting paper published:
16 June 2009
- Revised manuscript received:
22 September 2010
- Manuscript approved:
27 September 2010
- Published online:
1 January 2011
- Version of record:
1 January 2011
View Cart
