Page 239 - Principles of Applied Reservoir Simulation 2E

224 Principles of Applied Reservoir Simulation

will be no changes in operating strategy. Given a base case prediction, several
runs should be made to optimize reservoir performance within the constraints
imposed by the commissioners of the study. If the model is run with well P-l
switched from oil rate to bottom hole pressure control, the PI for well P-1 needs
to be calibrated to assure continuity in the oil rate. The following exercises are
designed to guide you through the prediction process.

Exercises

Exercise 22.1 Repeat the shut in time calculation using AJC = 1000 ft and Ay
= 1000 ft. The new shut in time Af 5 should be less than one hour.

Exercise 22.2 Run data set CS-XS.DAT with maximum timestep sizes ranging
from 15 days to 60 days. Select a maximum timestep size by monitoring the
material balance error and the stability of the solution. A solution is unstable
if it oscillates, that is, variables like GOR or WOR vary between a high and low
value from one timestep to the next.

Exercise 22.3 What is the effect of doubling the PID in data set CS-XS.DAT?

Exercise 22.4 How does model performance change if skin 5 = 0?

Exercise 22.5 What is the effect of reducing the well FBHP by 1000 psia? The
reduction in FBHP is one way to simulate gas lift or pumping.

Exercise 22.6 Data set CS-HM.DAT was used as the basis of the case study.
Run data set CS-HM.DAT and verify that it matches the data shown in Table
20-2.

Exercise 22.7 Several sensitivity runs may be made by varying model parame-
ters and noting reservoir performance. As an example of a sensitivity study, vary
the WOC by ±100 ft. How does this variation affect water breakthrough and oil
recovery during the history match period?