Abstract: A PCD cutting element for use in earth boring drill bits where die interstices remote from the working surface are filled with a catalyzing material and the interstices adjacent to the working surface are substantially free of the catalyzing material is described. An intermediate region between the substantially free portion and filled portion has a plurality of generally conically sectioned catalyst-free projections which taper down, extending to a second depth from the planar working surface, preferably about 0.5 times or more of the first depth.

Abstract: A PCD cutting element for use in earth boring drill bits where the interstices remote from the working surface are filled with a catalyzing material and the interstices adjacent to the working surface are substantially free of the catalyzing material is described. An intermediate region between the substantially free portion and filled portion has a plurality of generally conically sectioned catalyst-free projections which taper down, extending to a second depth from the planar working surface, preferably about 0.5 times or more of the first depth.

Abstract: A cutting structure for a rotary drag-type drill bit includes a cutting element mounted on a member on the bit body, which may be a carrier secured to the bit body or part of the bit body itself. The surface of the member on which the cutting element is mounted is formed with a groove, adjacent the cutting element. The downstream end of the groove is located near a nozzle in the bit body through which a jet of drilling fluid emerges, so that the groove directs to the front of the cutting element the flow of drilling fluid which impinges on the groove. An array of separate grooves may lead from the nozzle to different cutting elements. The flow of drilling fluid directed towards each cutting element serves to break up cuttings removed from the formation by the cutting element and to carry the cuttings away from the element.

Abstract: Formation engaging elements are moveably mounted onto a drill bit. Such elements may be used to protect other rigidly mounted formation engaging elements from impacts that occur during use of the drill bit, or they may be used to alter the aggressiveness of the drill bit when used in directional drilling operations.

Abstract: A cutting structure for a rotary drag-type drill bit includes a preform cutting element mounted on a carrier which, in use, is mounted on the drill bit and comprises a front facing table of superhard material bonded to a less hard substrate. A portion of the carrier on which the preform cutting element is mounted is shaped, adjacent the cutting element, for engagement by a chip of formation material being removed by the cutting element from the formation being drilled so as to tend to break the chip away from the surface of the formation. A portion of the carrier, or a portion of the bit body itself, may also be shaped, adjacent the cutting element, to direct to a location in front of the cutting element a flow of drilling fluid which impinges on said surface so as to assist in chip removal.

Abstract: A drilling assembly for drilling holes in subsurface formations comprises a drill bit 10, a drive unit 12 including a housing and a rotor 11 operatively coupled to the drill bit to rotate the drill bit relative to the housing, and a modulated bias unit 14 coupled to rotate with the drive unit housing and apply a lateral bias thereto in synchronism with rotation of the housing. The modulated bias unit 14 comprises one or more hydraulic actuators including members 16 which, in use, bear against the sides of the borehole, and means for modulating the pressure of fluid supplied to the actuators in synchronism with rotation of a component of the drilling assembly, and in selected angular phase relation thereto, whereby each hydraulic actuator is actuated in a selected rotational position of the component.

Abstract: A preform cutting element for a drag-type rotary drill bit includes a facing table of polycrystalline diamond bonded to a less hard substrate, such as cemented tungsten carbide. The element is formed by first forming a solid substrate, and then applying an electron beam, laser, or other intense heating source to adjacent areas of the front surface of the substrate to melt the surface and form an array of holes or holes therein. A layer of polycrystalline diamond particles is applied to the substrate so that such particles fill the holes or holes, and the diamond layer and substrate are then subjected to pressure and temperature in a high pressure, high temperature press to bond the superhard layer to the substrate. The engagement of parts of the diamond table in the holes or holes in the substrate provides a mechanical interlock to improve the strength of the bond between the table and substrate.

Abstract: The invention provides a stabilizer having integral steel blades with preformed apertures into which are cold pressed plugs of hard material, which is characterized in that some of the plugs of hard material inserted into the preformed holes in each blade, each have embedded therein and located exposed at the outer surface thereof, at least one diamond. Advantageously the diamond containing plugs are particularly located so that they are concentrated in those regions of the blade which, when the stabilizer is used in a borehole, are subjected to the greatest wear, viz. towards the leading end of each blade and at sharp changes of contour.