Page 206 - Principles of Applied Reservoir Simulation 2E

Part II: Reservoir Simulation 191

corporate managements and financial institutions the information they need to
make informed decisions.

19.5 Validity of Model Predictions

The validity of model predictions was studied by Saleri [1993] who
compared actual field performance with predicted performance. Figure 19-2

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History
ts"' 80 Forecast
o - Pressure 3200 7600
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3
^ " f^^^ w.. » "H ^"^ ^^" O o:
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O 82 $4 OO 80 £rv
7/me

Figure 19-2. Quality of field performance match (after Saleri,
1993; reprinted by permission of the Society of Petroleum
Engineers).
illustrates his results. The overall match of field performance, such as total rate
and pressure performance, is reasonable. The field match is somewhat deceptive
however, because the validity of individual well performance forecasting varies
widely. Indeed, the match of water and gas performance for about half of the
wells was deemed a "bust" by the author. This is not unusual in a model study,
Saleri arrived at the following conclusions:
4 "Barring major geologic and/or reservoir data limitations, fieldwide
cumulative production forecast accuracies would tend to range from 10%
to 40%." [Saleri, 1993]
4* "Well performance forecasts are bound to be less successful than
fieldwide predictions." [Saleri, 1993]