Run the Waterflood

Run It

The model is complete. Inject water at the injector and watch the front sweep the oil across the field to the producer, while the water cut and oil recovery build over pore volumes injected. This is a genuine two-phase flow solve, the physics the course built, running on the field you just made.

Breakthrough and Sweep

Before breakthrough the producer makes clean oil; when the front arrives the water cut climbs and recovery slows. Raise the oil viscosity and the mobility ratio turns unfavorable: the water fingers ahead, breaks through earlier, and leaves more oil behind.

Sweep and Support

Sweeping the oil is only half of what the flood does. The other half is pressure support. As the producer withdraws fluid the reservoir pressure would fall, but injecting water to replace that volume holds it up. The voidage replacement ratio measures how much you put back: keep it at one and the pressure stays near its initial value.

Let the voidage replacement slip below one and the reservoir depletes. Once the pressure falls below the bubble point, gas comes out of solution and the drive becomes an inefficient solution-gas mechanism that leaves most of the oil behind. That is why a waterflood injects: not only to push the oil, but to keep the reservoir energized while it does.

The Number That Decides

The recovery at the economic limit is the prize, oil-in-place times recovery factor, the reserves a development hangs on. From an empty structural envelope to this single number is the whole of reservoir modeling, and the whole of this course.