Drainage Area (A)

If a well is flowed until all the boundaries of the reservoir have been reached (boundary-dominated flow), the area defined within these boundaries is called the drainage area. The boundaries of a well’s drainage area could be physical boundaries, such as faults, or no-flow boundaries caused by nearby producing wells, as shown in the figure below.

This figure shows the wells that are evenly spaced and producing at the same rate, and thus no-flow boundaries develop (white lines) between the producing wells. In this situation, the drainage area of each well is defined by the no-flow boundaries around it.

Note:

Drainage area can be determined through PSS analysis, radius of investigation, or analysis of geological data or well spacing.