Abstract: A hole opener for use on drill strings in well bore enlargement operations featuring a bore follower extension and a stabilized cutter with poly crystalline diamond compact cutter elements arrayed in a plurality of cutting spiral patterns. Fluid jets are directed toward the cutter arrays and also directed to sweep the opener cut formation in groove regions between the cutter arrays. A hard metal chip covering is on the follower extension to open pilot hole bridges, assisted by a nose jet. Blade form vortex barriers are situated at the confluence of the cutter cleaning and formation sweeping fluid jets. The follower extension is tapered to increase the upward velocity of fluid rising past the extension.

Abstract: This invention relates to a method of making a drill string stabilizer such as a drill collar stabilizer. It includes the steps of providing a length of drill string or drill collar as the body of the stabilizer. There is also provided a cylindrical section of a thick-walled tubing having an inside diameter matching the outside diameter of the stabilizer body. A plurality of helical and elongated sections from the cylindrical section of tubing are cut to form a plurality of spiral blades. These blades are attached as by welding to the body of said stabilizer in a circumferentially generally equally spaced row thereabout. The cylindrical section of tubing is selected to have a predetermined outside diameter such that the blades will have a predetermined radial thickness when attached to the body. In addition each of the blades may be provided with a tapered end surface so as to facilitate running of the tool in the well bore.