the exit port 12 is correctly oriented the casing is typically cemented in place in the earth borehole after which a conventional fishing tool is run from the earth 39 s surface down through the casing 10 the internal sleeve 16 and out the lower end of the sleeve 16 although the fishing tool not illustrated can take various forms a typical fishing tool for this operation can have one way dogs which spring up upon exiting the lower end of the sleeve 16 and actually grapple the lower end of sleeve 16 by pulling up on the fishing tool the set screws 18 will shear out and the internal pressure sleeve can be retrieved to the earth 39 s surface following retrieval of the internal pressure sleeve 16 a conventional whipstock such as is illustrated in fig8 is lowered through the casing 10 and once oriented with the orientation of the exit port 12 for example through the use of a conventional key lug on the interior of the casing 10 is anchored immediately below the exit port 12 with the whipstock anchored in place and its running tool retrieved from the borehole a conventional drilling operation is commenced in which a drill bit at the lower end of a drillstring is lowered down to the whipstock and caused to drill off the whipstock through the fiberglass covered exit port 12 any cement outside the exit port and into the formation of interest 30 to replace the conventional key lug.