Abstract: A method for evaluating existing drill bits and drill bit designs includes measuring several desired characteristics of a bit, including the wear experienced in drilling a formation, such as an actual formation or a simulated formation or a laboratory test fixture. A computer model may be used to evaluate the work-force and/or the sliding-wear rates that cutting elements of the bit experience as compared with the rate-of-penetration and/or durability of the bit. This information may be used to design a new drill bit, which may involve modification of the cutting elements (e.g., moving the location, volume (size and shape) or number of cutting elements from areas of the bit that receive lower work-force and sliding-wear rates to those areas that experience relatively greater work-force and sliding wear-rates. This may permit the cutting elements to be oriented more aggressively relative to a formation to be drilled.

Abstract: A drill bit includes a bit body having a face on which two different types of cutting elements are disposed, the first type being cutting elements suitable for drilling at least one subterranean formation and the second type being cutting elements suitable for drilling through a casing bit disposed at an end of a casing or liner string and cementing equipment or other components, if such are disposed within the casing or liner string, as well as cement inside as well as exterior to the casing or liner string. The second type of cutting elements exhibits a relatively greater exposure than the first type of cutting elements, so as to engage the interior of the casing bit and, if present, cementing equipment components and cement to drill therethrough, after which the second type of cutting elements quickly wears upon engagement with the subterranean formation material exterior to the casing bit, and the first type of cutting elements continues to drill the subterranean formation.

Abstract: A rotary drilling apparatus and method for drilling subterranean formations, including a body being provided with at least one cutter thereon exhibiting reduced, or limited, exposure to the formation, so as to control the depth-of-cut of the at least one cutter, so as to control the volume of formation material cut per rotation of the drilling apparatus, as well as to control the amount of torque experienced by the drilling apparatus and an optionally associated bottomhole assembly regardless of the effective weight-on-bit are all disclosed. The exterior of the drilling apparatus may include a plurality of blade structures carrying at least one such cutter thereon and including a sufficient amount of bearing surface area to contact the formation so as to generally distribute an additional weight applied to the drilling apparatus against the bottom of the borehole without exceeding the compressive strength of the formation rock.

Abstract: A drilling tool including at least two cutting elements (e.g., redundant or upon a selected profile region) sized, positioned, and configured thereon so as to contact or encounter a change in at least one drilling characteristic of subterranean formation along an anticipated drilling path prior to other cutting elements thereon encountering same is disclosed. Methods of designing a drilling tool are also disclosed including placing such cutting elements upon the cutting element profile in relation to a predicted boundary surface along an anticipated drilling path. Methods of operating a drilling tool so as to initially contact a boundary surface between two differing regions of a subterranean formation drilled with at least two cutting elements is disclosed. The cutting elements configured on drilling tools and methods of the present invention may be designed for limiting lateral force or generating a lateral force having a desired direction during drilling associated therewith.

Abstract: A drill bit including a bit body having a face on which two different types of cutting elements are disposed, the first type being cutting elements suitable for drilling at least one subterranean formation and the second type being cutting elements suitable for drilling through a casing bit disposed at and end of a casing or liner string and cementing equipment or other components, if such are disposed within the casing or liner string, as well as cement inside as well as exterior to the casing or liner string. The second type of cutting elements exhibits a relatively greater exposure than the first type of cutting elements, so as to engage the interior of the casing bit and, if present, cementing equipment components and cement to drill therethrough, after which the second type of cutting elements quickly wears upon engagement with the subterranean formation material exterior to the casing bit, and the first type of cutting element continues to drill the subterranean formation.

Abstract: A rotary drag bit and method for drilling subterranean formations, including a bit body being provided with at least one cutter thereon exhibiting reduced, or limited, exposure to the formation, so as to control the depth-of-cut of the at least one cutter, so as to control the volume of formation material cut per bit rotation, as well as to control the amount of torque experienced by the bit and an optionally associated bottomhole assembly regardless of the effective weight-on-bit are all disclosed. The exterior of the bit preferably includes a plurality of blade structures carrying at least one such cutter thereon and including a sufficient amount of bearing surface area to contact the formation so as to generally distribute an additional weight applied to the bit against the bottom of the borehole without exceeding the compressive strength of the formation rock.

Abstract: A casing bit, which may comprise a composite structure, for drilling a casing section into a subterranean formation, and which may include a portion configured to be drilled therethrough, is disclosed. Cutting elements and methods of use are disclosed. Adhesive, solder, electrically disbonding material, and braze affixation of a cutting element are disclosed. Differing abrasive material amount, characteristics, and size of cutting elements are disclosed. Telescoping casing sections and bits are disclosed. Aspects and embodiments are disclosed including: at least one gage section extending from the nose portion, at least one rotationally trailing groove formed in at least one of the plurality of blades, a movable blade, a leading face comprising superabrasive material, at least one of a drilling fluid nozzle and a sleeve, grooves for preferential failure, at least one rolling cone affixed to the nose portion, at least one sensor, discrete cutting element retention structures, and percussion inserts.

Abstract: A method and apparatus for running a whipstock into a well bore attached to a combination mill and drill bit, releasing the mill/bit from the whipstock, milling a window in the casing, and drilling a lateral well bore, all in one trip. The mill/bit is provided with a primary cutting structure better suited for milling through the casing, and a secondary cutting structure, better suited for drilling through the earth formation. The secondary cutting structure is initially smaller in diameter than the primary cutting structure. The whipstock can be attached to the mill/bit with a shear bolt supported by a boss on the whipstock, with the boss designed to arrest axial motion of the mill/bit after shearing of the bolt.