Pseudosteady-State Flow

For the transient flow cases that were considered in the previous section, the well was assumed to be located in a very large reservoir. This assumption was made so that the flow from or to the well would not be affected by boundaries that would inhibit the flow. Obviously, the time that this assumption can be made is a finite amount and often is very short in length. As soon as the flow begins to feel the effect of a boundary, it is no longer in the transient regime. At this point, it becomes necessary to make a new assumption that will lead to a different solution to the radial diffusivity equation. The following sections discuss solutions to the radial diffusivity equation that allow calculations during the pseudosteady-state flow regime.