Smith International, Inc.

Per Ivar Nese

Gary Ray Portwood

Chris Edward Cawthorne

Madapusi K Keshavan

Michael Allen Siracki

James Carl Minikus

Dennis Cisneros

Gary Edward Garcia

J Daniel Belnap

Ronald K Eyre

Nathan R Anderson

Scott D McDonough

Alan W Lockstedt

Michael S Oliver

A rolling cone bit includes at least one cone cutter having a gage row of cutter elements and a first inner row of near but off-gage cutter elements that are positioned so as to divide the sidewall and bottom hole cutting duty so as to enhance bit durability, maintain borehole diameter and improve ROP. The off-gage distance of the first inner row of cutter elements is defined for various bit sizes to optimize the division of cutting duty. The distance that the first inner row of cutter elements are off-gage may be constant for all the cones on the bit or may be varied among the various cones to balance the durability and wear characteristics on all the cones of the bit.

Rolling cone bit with gage and off-gage cutter elements positioned to separate sidewall and bottom hole cutting duty

Enhanced inserts are formed having a cylindrical grip and a protrusion extending from the grip. An ultra hard material layer is bonded on top of the protrusion. The inserts are mounted on a rock bit and contact the earth formations off center. The ultra hard material layer is thickest at a critical zone which encompasses a major portion of the region of contact between the insert and the earth formation. Transition layers may also be formed between the ultra hard material layer and the protrusion so as to reduce the residual stresses formed on the interface between the ultra hard material and the protrusion.

Engineered enhanced inserts for rock drilling bits

A cutter element that balances maximum gage-keeping capabilities with minimal tensile stress induced damage to the cutter elements is disclosed. The cutter elements of the present invention have a non-symmetrical shape and may include a more aggressive cutting profile than conventional cutter elements. In one embodiment, a cutter element is configured such that the inside angle at which its leading face intersects the wear face is less than the inside angle at which its trailing face intersects the wear face. This can also be accomplished by providing the cutter element with a relieved wear face. In another embodiment of the invention, the surfaces of the present cutter element are curvilinear and the transitions between the leading and trailing faces and the gage face are rounded, or contoured. In this embodiment, the leading transition is made sharper than the trailing transition by configuring it such that the leading transition has a smaller radius of curvature than the radius of curvature of the trailing transition. In another embodiment, the cutter element has a chamfered trailing edge such that the leading transition of the cutter element is sharper than its trailing transition. In another embodiment, the cutter element has a chamfered or contoured trailing edge in combination with a canted wear face. In still another embodiment, the cutter element includes a positive rake angle on its leading edge.

Non-symmetrical stress-resistant rotary drill bit cutter element

A rolling cone bit includes a cone cutter having a gage row and an adjacent nestled gage row of cutter elements that are positioned on gage so as to divide or share the borehole corner cutting duty. The wear resistance, hardness, toughness and shape of the cutter elements in the adjacent rows are optimized depending upon the type of cutting the respective rows perform, the characteristics of the formation being drilled and the drilling techniques being employed. In most applications, the nestled gage cutter elements will have cutting surfaces that are more wear resistant or harder than the cutting surfaces of the gage cutter elements which experience more bottom hole duty. The nestled gage cutter elements engage the borehole wall with a negative rake angle for increased durability. Preferably, the nestled gage cutter elements have continuously contoured and non-shearing cutting surfaces.

Rolling cone bit having gage and nestled gage cutter elements having

A rotary cone bit for drilling bore holes in earth formations whose body has a thread pin end and a dome end from which extend three legs. A cutter cone is rotatably mounted to each leg and is radially oriented about the bit's central axis. Each cutter cone has a gage row of cutting elements extending from the cone surface nearest the mouth and a nose row extending nearest the cone's apex. A center jet for emitting fluid or mud is located on the dome. The jet has a converging nozzle with an exit orifice which extends below a predefined horizontal plane intersected by the cones or cutting elements. The exit orifice has a constant diameter for a length at least equal to its diameter for reducing the diffusion of the fluid or mud flow emitted. Fluid or mud emitted from the center jet travels substantially uninterrupted within a cylindrical space between the cones which is not invaded by any cutting element. This reduced diffusion substantially uninterrupted fluid flow strikes the bore hole bottom with maximum impact energy for enhanced removal of earth formation cuttings.

Rock bit with an extended center jet

A rolling cone bit includes a cone cutter having a pair of adjacent rows of cutter elements that are positioned so as to divide the sidewall and bottom hole cutting duty. The wear resistance, hardness and toughness of the cutter elements in the adjacent rows are optimized depending upon the type of cutting the respective rows perform. In most applications, the cutter elements experiencing more sidewall cutting will have cutting surfaces that are more wear resistant or harder than the cutting surfaces of cutter elements in rows experiencing more bottom hole duty. Likewise, the cutter elements exposed to more bottom hole duty will generally be tougher than those experiencing substantial sidewall cutting. The material enhancements include varying the grades of tungsten carbide used in the cutter elements and by selectively employing layers of super abrasives, such as PCD or PCBN. The cutter elements may be either inserts or steel teeth.

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Houston, TX, United States of America

Per Ivar Nese