Page 169 - Principles of Applied Reservoir Simulation 2E

154 Principles of Applied Reservoir Simulation

modeled with a black oil simulator. The applicability of this rule depends on the
objectives of the study.
The pressure range associated with fluid property data should cover the
entire range of pressures expected to be encountered over the life of the field.
The data should be smooth to enhance computational efficiency and to ensure
data consistency. A check on data consistency is a calculation of fluid compress-
ibility. If a negative compressibility is encountered, the data need to be corrected.
The problem of negative compressibility occurs most often when data is
extrapolated beyond measured pressure ranges.
Flow units should be determined by reviewing geological and petro-
physical data. It is possible to represent the behavior of a flow unit by defining
a set of PVT and Rock property tables for each flow unit. PVT property tables
contain data that describe fluid properties, while Rock property tables represent
relative permeability and capillary pressure effects. Each set of PVT or Rock
property tables applies to a particular region of gridblocks, hence the collection
of blocks to which a particular set of PVT or Rock property tables applies is
referred to as a PVT or Rock region. The number of flow units, and the
corresponding number of PVT and Rock regions, should be kept to the minimum
needed to achieve the objectives of the study. This statement is another
application of Ockham's Razor (Chapter 17).

Exercises

Exercise 15.1 Data file EXAM8.DAT has a gas well under LIT control.
Determine the effect of doubling the turbulence factor on gas rate, cummulative
gas production, and reservoir pressure at the end of the run. See Chapters 25.2
and 30 for more discussion.

Exercise 15.2 WINB4D contains a few fieldwide controls (see Chapter 24.8).
Data file EXAM4.DAT is a 2D areal model of an undersaturated oil reservoir
undergoing primary depletion. Modify data file EXAM4.DAT so that fieldwide
pressure is not allowed to drop below the initial bubble point pressure using the