A cutting insert includes a plurality of consecutively disposed, interlinked individual cutting inserts that can be brought into use successively through a respectively interposed predetermined breaking point by detaching a respectively preceding individual cutting insert in cutting use. The cutting insert has a blade-shaped construction with lower and upper bearing surfaces for being held in an elongated cutout with lower and upper opposing surfaces in a basic tool body of a grooving and cut-off tool or disk milling cutter. Each individual cutting insert is provided with a positioning device that cooperates with a complementary positioning device of the basic tool body. A grooving and cut-off tool or disk milling cutter and a wrench for the cutting insert, are also provided.

A method and apparatus for milling a window in a downhole structure, such as a casing or a liner, includes a mandrel that supports milling elements arranged in a predetermined pattern. In one example, the milling elements are arranged in one or more continuous channels each having a generally helical pattern. The milling elements are able to cut the window in the downhole structure substantially continuously to the desired size.

The present invention generally relates to a cutting insert for use with wellbore milling tools. The cutting insert forms an angle between a milling surface of the insert and a surface of the tool that the insert is attached to in order to provide the proper cutting incline, and substantially perpendicular sides of the insert relative to the milling surface of the insert provide continuous support for the milling surface. In addition, the inserts can comprise spacers and legs that evenly distribute bonds formed between inserts and bonds formed between the inserts and the surface of the tool, respectively. Selecting the dimensions of the spacers and legs alters the strength of the bonds.

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.

An assembly for shielding an implanted medical device from the effects of high-frequency radiation and for emitting magnetic resonance signals during magnetic resonance imaging. The assembly includes an implanted medical device and a magnetic shield comprised of nanomagnetic material disposed between the medical device and the high-frequency radiation. In one embodiment, the magnetic resonance signals are detected by a receiver, which is thus able to locate the implanted medical device within a biological organism.