1. n. [Well Testing]

A virtual well used to mathematically create the effect of a flow barrier. The pressure transient behavior both at the well and in the reservoir is identical for the following two cases: 1) a well near a barrier represented by a plane normal to the bedding, or 2) a well producing or injecting at the same rate as the tested well. In the second case, the effect is of a barrier bisecting the space between the two wells.

See: bed,  injection well,  producing well