1. Water Drive Reservoir Performance Prediction
Title slide
Prospecting w/Electric Logs
And Formation Evaluation
Repeat Title, Give Name and work history
you may also need to include Location and/or
Dr.Mostafa Mahmoud Kinawy

2. How to predict the future performance of a water drive reservoir
We have five unknowns: Np Wp Gp
We and
Pressure,P
And we have two equations represents Water drive reservoir :
Marerial balance equation
Water influx model

3. So, you must assume three of these unknowns.
Np, Wp ,Gp from production plane (1,3/4.1/2 and ¼ years) or
From production decline curves. Then we can get the other three unknowns (We and P)
Because we have two equations and two unknowns.
1-The Material Balance Equation:
A We = Np BO +WP BW –NBOi Ce P (for water drive
reservoir above the bubble point pressure
B We = Np [Bt + (Rp-Rsi) Bg ] +WpBw –N(Bt-Bti) for
water drive reservoir below the bubble point pressure

4. 2-Water influx models
A-We = K ∑  p  t (for steady state water influx )
B- We = c ∑  p  t (for semi steady state water influx)
log a t
C- We = B ∑ Wed  p for Unsteady state water influx
Future performance of water drive reservoir can be done as follows:
1- Select a combination of oil ,water and gas production. This can be obtained from the production
plane (if any) . If not, the production data at future period can be estimated from the production decline curves.

5. 2-Assume three values of an expected pressure at the respective future period (1/4,1/2,3/4,1 year) and then three values of cumulative water influx by both the material balance equation and water influx model which must be determined before starting process using the previously described procedure.
3- Plot We calculated from both material balance equation and water influx model versus pressure on the same graph as shown in the following figure.
4- The intercept point will give the reservoir pressure and water influx which satisfy the selected production data.
Go to the next future period and repeat the above procedure.

6. Water influx model We
M.B .Equation
Pressure