Page 115 - Principles of Applied Reservoir Simulation 2E

100 Principles of Applied Reservoir Simulation

analysis gives modelers more detail than they can use. Even today, with 100,000
to one million gridblock flow models, modelers cannot use all of the information
that is provided by computer-based geologic models. Computer-based geologic
models often have in excess of one million grid points. It is still necessary to
coarsen detailed geologic models into representative flow units.
An understanding of the big picture, even as a simple sketch, is a valuable
resource for validating the ideas being quantified in a model. Richardson, et al.
[ 1987b] sketched several common types of reservoir models: a deep-water fan;
a sand-rich delta; a deltaic channel contrasted with a deltaic bar, etc. Their
sketches illustrate what the reservoir might look like for a specified set of
assumptions. A sketch such as Figure 11-4 is a good tool for confirming that
people from different disciplines share the same concept of a reservoir; it is a
simple visual aid that enhances communication. In many cases, especially the
case of relatively small fields, the best picture of the reservoir may only be a
qualitative picture. When a more detailed study begins, the qualitative picture
can be upgraded by quantifying parameters such as gross thickness in the con-
text of the conceptual sketch of the reservoir.

Figure 11-4. Mississippi Delta.
Confidence in model performance is acquired by using the model to match
historical field performance. History matching and model validation will be
discussed in greater detail later. From a technical perspective, flow models
should be updated and refined as additional information is obtained from the