bilinear flow

1. n. [Well Testing]
A flow regime resulting from combined simultaneous linear flow in perpendicular directions. This flow regime is seen most commonly in tests of hydraulically fractured wells and occurs for finite-conductivity fracture where linear flow exists both in the fracture and to the fracture plane. This flow regime is recognized as a 1/4 slope in the pressure derivative on the log-log diagnostic plot. Its presence enables determination of the fracture conductivity.