Page 106 - Principles of Applied Reservoir Simulation 2E

Part II: Reservoir Simulation 91

Surface Model

• Wellbore Model

Figure 10-1. Reservoir management system.

Every practical reservoir simulator includes both a reservoir model and
a well model. The well model is a term in the fluid flow equations that represents
the extraction of fluids from the reservoir or the injection of fluids into the
reservoir. Full-featured commercial simulators also include a wellbore model
and a surface facility model. The wellbore model represents flow from the
sandface to the surface. The surface model represents constraints associated with
surface facilities, such as platform and separator limitations.

Unconformity

Figure 10-2. Subdivide reservoir.

The mathematical algorithms associated with each model depend on
physical conservation laws and empirical relationships. Computer simulators
are based on conservation of mass, momentum, and energy. The most widely
used simulators assume the reservoir is isothermal, that is, constant temperature.
If we are modeling a reservoir where thermal effects matter, such as a secondary