Page 190 - Principles of Applied Reservoir Simulation 2E

Part II: Reservoir Simulation 175

The cost of a simulation study can be estimated based on previous experi-
ence with similar studies. As an example of how to estimate the cost for a black
oil simulation study, begin by calculating the product of the number of
gridblocks and the number of timesteps denoted by GBTS. Once GBTS is
known, it should be related to the computer processing (cpu) time needed to
make a ran. The amount of cpu time per GBTS is determined by dividing the
cpu time needed to make previous model runs by the number of GBTS in those
runs. The product of GBTS and cpu time per GBTS gives total cpu time needed
for a run. The cost of the study then depends on the number of runs that need
to be made. The number of runs can be estimated by assuming that approxi-
mately 100 runs will be needed to obtain a history match. A similar approach
is applied to estimating the cost of making predictions. Personnel cost Is
approximately equal to computer cost for the study, This does not include the
cost of data collection and evaluation.

Exercises

Exercise 17.1 Data set EXAM10.DAT uses multiple Rock and PVT regions.
Review EXAM 10.DAT and simplify the data set without altering model results.
List the changes you make to the data set. Chapter 24.4 presents a description
of Rock and PVT region data records.

Exercise 17.2 A model has 10 * 10 x 4 gridblocks and takes 5 minutes to ran
100 timesteps. Calculate cpu time per GBTS. Estimate how long it would take
to make 100 runs with 200 timesteps each.

Exercise 17.3 (A) Use Eq. (17.3) to calculate the equivalent well block radius
of a block with Ax = Ay = 200 ft. (B) Estimate shut in time for the Peaceman
5
1
correction using Eq. (17.1). Assume <J> = 0.15, C T= I * 10~ psia" , jl = 2 cp and
K=10md.