Page 112 - Principles of Catalyst Development

Part II: Reservoir Simulation 93

120 . . , . .
if 100 ; '• • ,• • : Actual
I. 80 ' ' : ; ! ' . . - • - * " • : _ . ' : 1981
•S 60 ._!_! "
Q. ./ . V - " 1984
R ^O . / . ! ^ w .'. i „ * r * •
CL. 1987
*— ' - - '• • \ Is - ..***.-**
== 20 V"»~"~"'~"~*-- * * . . •
O : i 1991
O i ' '
1975 1981 1986 1991 1996
Year
Figure 10-3. Price forecasting.

Forecasts that were made in years 1981, 1984, 1987, and 1991 are compared
to the actual prices. Even though price forecast is essential to a commercial
enterprise, it is clear from Lynch's study that there is considerable uncertainty
associated with the price forecast. The wide swing in oil price in the late 1990's
where oil price varied by a factor of two indicates the volatility of economic
factors that are needed in forecasts.
In addition to uncertainty in economic parameters, there is uncertainty
in the forecasted production performance of a field. Forecasts do not account
for discontinuities in historical patterns that arise from unexpected effects. This
is as true in the physical world as it is in the social [Oreskes, et al, 1994].
Simulators do not eliminate uncertainty; they give us the ability to assess and
better manage the risk associated with the prediction of production performance.
A valuable but intangible benefit of the process associated with reservoir
simulation is the help it provides in managing the reservoir. One of the critical
tasks of reservoir management is the acquisition and maintenance of an up-to-
date data base. A simulation study can help coordinate activities as a modeling
team gathers the resources it needs to determine the optimum plan for operating
a field. Collecting input data for a model is a good way to ensure that every
important technical variable is considered as data is collected from the many
disciplines that contribute to reservoir management. If model performance is
especially sensitive to a particular parameter, then a plan should be made to
determine that parameter more accurately, for example, from either laboratory
or appropriate field tests.