Abstract: A method is provided that allows the operator to re-enter a primary wellbore from a lateral wellbore after the lateral wellbore has been completed. The method generally comprises the steps of locating a cutting device such as a milling bit adjacent a tubular such as a liner within a wellbore, rotating the milling bit while maintaining an axial position of the milling bit relative to the liner to initiate an opening, and rotating and axially advancing the milling bit to complete the opening. In addition, a bottom hole assembly that facilitates re-entry into the primary wellbore from a lateral wellbore is provided. The bottom hole assembly generally includes a drill collar or other heavy pipe structure, and a mill. The mill has a body and cutting structures. The cutting structures apply lateral force against a surrounding pipe to form an initial lip through the wall of the pipe.

Abstract: Wellbore apparatus has been invented that includes a whipstock with a top and a bottom, the whipstock disposed in a wellbore extending down from an earth surface into the earth, the wellbore having an inner surface, a mill guide with a body having an upper end, a lower end, and a channel therethrough from the upper end to the lower end, and a portion of the lower end of the mill guide disposed between and held between the inner surface of the wellbore and an outer surface of the top of the whipstock.

Abstract: A method for milling an opening, slot, hole, or window in a tubular of a tubular string in a wellbore, has been invented which includes installing a mill system in the tubular at a desired milling location, and milling an opening in the tubular. In one aspect the method includes using a mill which has a weight member below the mill, above the mill, or both. In one aspect additional weight is added to the weight member once it has been introduced into the tubular string.