WHIPSTOCK

摘要

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 with a groove shape corresponding to the nose shape of the nose of the first mill, the sacrificial element made of readily millable material, the at least one surface of the sacrificial element for abutment by the first mill, the at least one surface including a curved surface having a curved shape corresponding to a curved outer shape of the first mill to enhance guiding contact between the first mill and the curved surface.