Abstract: An apparatus and method are provided for completion of a horizontal section of a subterranean well. The apparatus comprises a first packer assembly which is settable in the well by longitudinal manipulation of a tubular workstring. A second packer is carried into the well on the workstring and is settable by application of hydraulic pressure through the workstring. A perforating gun is carried into the well on and in communication with the workstring, together with a gun retractor for telescopically retracting the perforating gun. A valve is also provided for selective communication between the exterior and the interior of the apparatus and is manipulatable to the open position to effect, for example, a fluid flow path from the production zone to the top of the well for transmission of production fluids in the well.