TABLE OF CONTENTS With the knowledge of Nodal analysis, it is possible to forecast well production, that is, future production rate and cumulative production of oil and gas. Combined with information of oil and gas prices, the results of a production forecast can be used for field economics analyses.
A production forecast is performed on the basis of principle of material balance. The remaining oil and gas in the reservoir determine future inflow performance relationship (IPR) and, therefore, production rates of wells. Production rates are predicted using IPR (see Chapter 3) and tubing performance relationship (TPR) (see Chapter 4) in the future times. Cumulative productions are predicted by integrations of future production rates.
A complete production forecast should be carried out in different flow periods identified on the basis of flow regimes and drive mechanisms. For a volumetric oil reservoir, these periods include the following:
Transient flow period
Pseudo-steady one-phase flow period
Pseudo-steady two-phase flow period
The production rate during the transient flow period can be predicted by Nodal analysis using transient IPR and steady flow TPR. IPR model for oil wells is given by Eq. (3.2), that is,
Equation 7.1 can be used for generating IPR curves for future time t before any reservoir boundary is reached by the pressure wave from the wellbore. After all reservoir boundaries are reached, either pseudo-steady-state flow or steady-state flow should prevail depending on the types of reservoir boundaries. The time required for the pressure wave...
