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: Wellbore operations (e.g. for milling and/or drilling) are disclosed which require a reduced number of tool trips into a wellbore to create a cut-out pocket, opening, or window in a tubular such as casing in the wellbore; and, in some aspects, to continue into a formation adjacent a main wellbore forming a lateral wellbore in communication with the main wellbore. Preferably one trip is required to complete a window or a window and the lateral wellbore. In one aspect a full gauge tool body is used so that the completed lateral wellbore is of a substantially uniform diameter along its entire length, which, in one aspect is suitable for the passage therethrough of full gauge tools, pipe, devices, and apparatuses. In one aspect a cutting system has cutting apparatus initially covered with a wearable away material which is worn away by contacting a tubular to be milled, exposing the cutting apparatus for milling and/or for drilling formation adjacent the wellbore.

Abstract: The present invention discloses, in certain preferred aspects, a whipstock with a body with a top, a bottom, and a cavity in the body, a sacrificial element secured to the top of the body, the sacrificial element having at least one surface for abutment by a first mill moving down adjacent the whipstock to guide the first mill while the first mill mills a tubular in which the whipstock is positioned and the sacrificial element for inhibiting the mill from contacting the body, the first mill having a curved outer shape and a nose projecting downwardly therefrom, the nose having a nose shape, the cavity defined by sides of the body and having filler material therein, the sides of the body presenting a face for abutment by a second mill while the second mill moves down adjacent the whipstock to mill a window in the tubular, the face for guiding the second mill and inhibiting the second mill from contacting the body other than the sides thereof defining the cavity, the sacrificial element having a groove therein