Page 193 - Principles of Applied Reservoir Simulation 2E

178 Principles of Applied Reservoir Simulation

Table 18-1
Suggested History Matching Procedure

Step Remarks
Match volumetrics with material balance and identify aquifer support.

II Match reservoir pressure. Pressure may be matched both globally and
locally. The match of average field pressure establishes the global
quality of the model as an overall material balance. The pressure
distribution obtained by plotting well test results at given points in time
shows the spatial variation associated with local variability of field
performance.
Ill Match saturation dependent variables. These variables include water-
oil ratio (WOR) and gas-oil ratio (GOR). WOR and GOR are often the
most sensitive production variables in terms of both breakthrough time
and the shape of the WOR or GOR curve.

IV Match well flowing pressures.

The pressure is usually the first dynamical variable to be matched during
the history matching process. A comparison of estimated reservoir pressures
obtained from well tests of a single well on successive days shows that errors
in reported historical pressures can be up to 10 percent of pressure drawdown.
This error may be as large or larger than the Peaceman correction discussed in
Chapter 17. As a first approximation, it is sufficient to compare uncorrected
historical pressures directly with model pressures, particularly if your initial
interest is in pressure trends and not in actual pressure values. Pressure
corrections should be applied when fine tuning the history match.
Production rates are usually from monthly production records. The
modeler specifies one rate or well pressure, and then verifies that the rate is
entered properly by comparing observed cumulative production with model
cumulative production. After the rate of one phase is specified, the rates of all
other phases must be matched by model performance. In many cases, observed
rates will be averaged on a monthly or quarterly basis and then compared with