Summary
In simulating enhanced-oil-recovery (EOR) processes, it is critical that all
the flow behaviors be properly accounted for in the simulation. Because of
computation limitations, long calculation time, and complexity of physics,
geological models cannot be directly used for fieldwide simulations. Upgridding
reduces the number of gridblocks in the simulation model and therefore makes
the simulation more efficient. An appropriate upgridding process needs to
preserve the dynamic behavior of the fine-scale model.
We propose such an analytical methodology. Our new technique is based on
preserving the characteristics, which are based on the fractional-flow concept
specifically modified for vertical flow between the layers. We develop our
method with a specific application to gravity-dominated displacement. In
upgridding the fine-scale model, we have developed a criterion by which the
sequence in which the fine-scale layers are combined is proposed such that
fractional-flow characteristics based on the fine-scale model are honored.
Using this methodology, we can determine not only the sequence in which layers
are combined, but also to what extent we can upgrid the fine-scale model.
The proposed methodology is developed for two-phase, 2D flow under the
effect of gravity-segregated displacement. However, it is also tested for
three-phase, 3D flow in gravity-dominated displacement with moderate effect of
viscous and capillary forces. The proposed solution is analytical; therefore,
it is computationally efficient. We have validated the methodology with both
synthetic and field examples and demonstrate that the proposed methodology is
superior to conventional proportional layering and variance-based
methodologies.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
4 March 2010
- Meeting paper published:
25 April 2010
- Revised manuscript received:
21 February 2011
- Manuscript approved:
5 May 2011
- Published online:
12 October 2011
- Version of record:
23 December 2011
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