Page 177 - Principles of Applied Reservoir Simulation 2E

162 Principles of Applied Reservoir Simulation

jector and each other, the grid orientation altered the expected flow pattern,
Figure 16-6 shows the effect on frontal advance. In this case, the front arrives
sooner at the producer in the upper right than the producer in the upper left. If
these results are incorporated in a reservoir management plan, they can reduce
the overall effectiveness of the plan.

Figure 16-6. Grid orientation effect (after Hegre, et al.
1986; reprinted by permission of the Society of
Petroleum Engineers).

Another example of the grid orientation effect arises in connection with
the modeling of pattern floods.
Figure 16-7 illustrates two grids
that can be used to model flow
in a five-spot pattern. The paral-
lel grid results in earlier break-
through of injected fluids than
the diagonal grid. This effect
can be traced to the finite
difference representation of the
fluid flow equations.
Most finite difference
simulators only account for Figure 16-7. Parallel and diagonal grids (after
d
9 2; r rinted
flow contributions from blocks T° .' * al 1 ^ f ^ Permission of
the Society of Petroleum Engineers).