Page 81 - Principles of Applied Reservoir Simulation 2E

66 Principles of Applied Reservoir Simulation

sophisticated reservoir flow models.

100
K^-^
E

0
0 60
Recovery Efficiency, % OOIP
A: Liquid and Rock Expansion
B: Solution Gas Drive
C: Gas Cap Expansion
D: Gravity Drainage
E: Water Influx

Figure 8-1. Comparison of primary production
mechanisms

If we rearrange the terms in the general material balance equation for an
oil reservoir, Eq. (2.3), we can estimate the relative importance of different drive
mechanisms. The indices representing different drives are given in Table 8-1
relative to the hydrocarbon production given by

- + G^ (8.1)
D HC = N pB 0 + [C ps N pR so]B g

Table 8-1
Drive Indices from the Schilthuis Material Balance Equation
Drive Index
Solution Gas I sg = ND 0/D HC

Gas Cap I gc = ND go/D HC
Water I w = [(W e-W p)B w]ID HC
Injected Fluids ^[Wfo + GpllDne

Connate Water and Rock Expansion I^mDr + D^+NDJ/DHc