This paper addresses interference testing in reservoirs with conductive fau
lts allowing fluid flow along and across the fault plane. An altered skin r
egion around fault thrusts is also included. It is found that the classical
line-source solution does not apply. When active and observation wells are
located across a fault, the interference behavior resembles that of a hydr
aulically fractured well with bilinear how characteristics. However, differ
ent flow regimes are developed on the pressure derivative when the well pai
rs are situated at the same side: initially, the basic line-source behavior
; then, constant pressure effect from the fault represented by a negative u
nit-slope line; and, finally, bilinear flow. Interference type curves for v
arious regions in the reservoir are developed and practical guidelines are
provided for interpretation of these tests. Field data from an interference
test in a faulted carbonate reservoir are analyzed and fault parameters ar
e estimated.