Summary
This paper presents verification of the Fevang and Whitson (1996)
gas-condensate pseudopressure method for layered reservoirs. Layers may be
characterized by widely varying permeability and composition, and they may be
communicating or noncommunicating. The pseudopressure method is used in well
calculations for coarse-grid models with relatively large areal grid dimensions
(>50 m), capturing near-well condensate blockage without local grid
refinement, thereby reducing run time and model size.
The paper presents examples from several field studies and from two
synthetic systems using a commercial reservoir simulator. The field studies
include rich- and lean-condensate reservoirs.
The study was conducted using a commercial compositional reservoir
simulator. Three-dimensional multilayer, fine-grid (radial and Cartesian)
models and equivalent coarse-grid models were used. Both depletion and
gas-injection cases were simulated for a wide range of reservoir fluids.
Reservoir performance of fine-grid models and coarse-grid models was compared
using the gas-condensate pseudopressure method and showed comparable results in
all cases studied, including relative permeabilities with capillary-number
dependence and high-velocity (β) flow treatment.
The coarse-grid model with pseudopressure is somewhat dependent on
coarse-grid size, generally requiring Δx=Δy≈ 50–100 m for lean gas condensates
and Δx=Δy≈100–200 m for rich gas condensates.
The paper verifies for the first time that the gas-condensate pseudopressure
method as proposed by Fevang and Whitson (1996) is valid and accurate for
layered systems with significant heterogeneity (permeability variation), with
and without crossflow, with and without capillary-number modification of
relative permeabilities, and for widely ranging fluid compositions in each
layer.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
12 September 2008
- Meeting paper published:
3 November 2008
- Revised manuscript received:
15 February 2009
- Manuscript approved:
7 March 2009
- Published online:
25 March 2010
- Version of record:
20 April 2010
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