Page 246 - Principles of Applied Reservoir Simulation 2E

Part IV: WINB4D User's Manual 231

bubble point pressure case. In this case, BOAST II reservoir pressures were
consistently lower than other simulator values. A mass conserving expansion
of accumulation terms can improve the accuracy for variable bubble point
pressure problems [Fanchi, 1986], but the mass conserving expansion option
requires additional run time and is not included in WINB4D.

Table 23-2
Comparison of Computational Differences
FEATURE BOAST II WINB4D
Interpolation B b g=\IB,
S
Improves material
balance
Saturation table end Set to -0.1 and 1.1 Set to 0.0 and 1.0
points
Timestepping and Counter and user Simplify to user
reports specified specified only
Debug codes Optional Deleted
Restart Available Deleted - restart by
specifying arrays

Stabilized IMPES Available Deleted - not robust

WINB4D retains the robustness of BOAST II while substantially
increasing program accuracy. WINB4D has an improved interpolation algorithm
that reduces material balance error for some problems by as much as a factor
of ten relative to the DOE versions BOAST and BOAST II. This feature
increases the range of applicability of WINB4D and is especially valuable for
gas and gas-oil systems. The algorithm does not degrade program speed.

23.1 Program Configuration

The user needs to have at least 1 Megabyte RAM to run WINB4D. The
version of WINB4D accompanying this book allows the user to define grids with
up to 1000 gridblocks. Parameters that may be dimensioned by the user at the
time of the run are listed below.