Abstract: A roller cone bit may be used as a rotating drag bit by treating the roller cones as carriers for a plurality of distinguishable types of drag cutters. The roller cones are each coupled to a mechanism which selectively allows rotation of the roller cones. The roller cones are otherwise fixed and as the bit is rotated, the drag cutters are brought into engagement with the rock. However, where the roller cones are selectively allowed to rotate, rotation of the drag bit rotates the roller cones to bring a second set of drag cutters into a configuration for cutting the rock formation. A mechanism then selectively locks the roller cones to prevent further rotation, keeping the second set of drag cutters fixed in place. By selectively permitting and preventing rotation of the roller cones, a plurality of sets of drag cutters can be brought into a configuration for cutting the rock.

Abstract: A drill bit having thermally stable PCD cutting elements includes a matrix body element having a plurality of spaced cutting elements supported in a body of matrix material such that a substantial portion of the cutter is above the body matrix and a minor portion is received within the body matrix. The cutters have side surfaces exposed and are so positioned that at least in some of the cutters more surface area of one side face is exposed as compared to the other side faces. The cutter support may include a small pad of matrix material to reduce the loading directly on the PCD. In a preferred form the PCD elements are mounted on pads or blades formed by spaced channels. The hydraulics are straight radial flow and improved hydraulic flow is achieved through the use of waterways which concentrate the fluid flow near the face of the cutters. In one form, improved hydraulics are obtained by having one fluid discharge port for each of the radially disposed fluid channels.

Abstract: An improved core catcher for use within a coring tool is provided by shaping the lower portion of the core catcher so as to form a collapsible lower section. The collapsible lower section is structurally collapsed as the core catcher is longitudinally displaced within the coring tool to exert a radially compressive force against the core and to thereby seize the core and retain it within the coring tool. In one embodiment, the collapsible lower section is resilient so that it collapses and after operation resumes its original configuration for reuse. In another embodiment, the collapsible lower section is crushable and is therefore not reusable after the first use. The reusable core catcher is devised by providing the lower section of the core catcher with a plurality of thin slots appropriately aligned and extending through the lower section of the core catcher.