In this paper, solutions to the 3D transient flow mathematical model f
or horizontal wells in box-rounded reservoirs are presented. The solut
ions are derived in Laplace transform domain by employing integral tra
nsform and point-source superposition. Both efficient computation of p
ressure responses and practical technology of oil field application me
ntioned here may be used to interpret the data from unsteady-state hor
izontal well testing.