Smith International, Inc.

Dennis Cisneros

Gary Ray Portwood

Chris Edward Cawthorne

James Carl Minikus

Per Ivar Nese

Gary Edward Garcia

Scott D McDonough

Madapusi K Keshavan

Sujian Huang

Michael Allen Siracki

Amardeep Singh

Bala Durairajan

Alan W Lockstedt

Carl M Hoffmaster

Quan V Nguyen

Michael S Oliver

Charles H S Douglas, Iii

A drill bit for drilling a borehole comprises a bit body having a bit face. In addition, the drill bit comprises a plurality of primary blades. Further, the drill bit comprises a plurality of primary cutter elements mounted to each primary blade and at least one backup cutter element mounted to each primary blade. Still further, the drill bit comprises a plurality of secondary blades. Moreover, the drill bit comprises a plurality of primary cutter elements mounted to each secondary blade. The ratio of the total number of backup cutter elements mounted to the plurality of primary blades to the total number of backup cutter elements mounted to the plurality of secondary blades is greater than 2.0. Each backup cutter element on each primary blade has substantially the same radial position as one of the primary cutter elements on the same primary blade.

Fixed cutter bit with backup cutter elements on primary blades

A roller cone drill bit includes a bit body adapted to be rotated about a longitudinal axis. At least one leg which terminates in a shirttail portion depends from the bit body. The shirttail portion defines a first end face having a first circumferential groove thereon. The first circumferential groove has a radius equal to the radius of a tip of the shirttail portion. A journal is cantilevered from the leg, and a roller cone is rotatably mounted on the journal. The roller cone has a second end face adjacent to the first end face. A second circumferential groove is formed on the second end face.

Roller cone drill bit shale diverter

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

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 cutter element having a substantially flat wear face and leading compression and trailing tension zones, wherein the leading compression zone is sharper than the trailing tension zone. Sharpness is defined as either a smaller inside angle at the intersection of a pair of planes or as a smaller radius of curvature. The cutter element of the present invention experiences reduced stress on its trailing portion in the direction of cutting movement and therefore is less subject to extreme impact damage and cyclic fatigue. The present invention can be applied with particular advantage to heel row cutters, but can also be applied to cutters in other rows that primarily ream the borehole wall and cooperatively cut the borehole corner. The present cutter element can be constructed so as to have either a positive or negative rake angle at its leading compression zone, or to have any of a variety of shapes, depending on the characteristics of the formation in which it is to be used.

Cutter element adapted to withstand tensile stress

A steel tooth, particularly suited for use in a rolling cone bit, includes a root region, a cutting tip spaced from the root region and a gage facing surface therebetween. The gage facing surface includes a knee, and is configured such that the cutting tip is maintained at a position off the gage curve. So positioned, the cutting tip is freed from having to perform any substantial cutting duty in the corner on the borehole corner, and instead may be configured and optimized for bottom hole cutting duty. The knee on the gage facing surface is configured and positioned so as to serve primarily to cut the borehole wall. It is preferred that the knee be positioned off gage, but that it be closer to the gage curve than the cutting tip.

Steel tooth cutter element with gage facing knee

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 steel tooth bit includes one or more rolling cone cutters having a generally conical surface, a heel surface, and preferably a transition surface therebetween. A row of gage cutter elements are secured to the cone cutter on the transition surface and have cutting surfaces that cut to full gage. A first inner row of off-gage steel teeth is positioned on the conical surface of the cone cutter so that the gage-facing cutting surfaces of the teeth are close to gage, but are preferably off-gage a distance D at a knee that is formed on the gage facing surface. Distance D is strategically selected such that the gage and off-gage cutter elements cooperatively cut the corner of the borehole. The lower most portion of the gage facing surface of these steel teeth are off gage a distance D' which is greater than D so as to bring the cutting tip of the teeth off gage to prevent undesired wear and rounding off of the tip of the cutter element. The upper most portion of the gage-facing surface is also preferably off gage a distance D' that is greater than D so as to optimize the surface area on the gage facing surface that is in contact with the borehole corner.

Rolling cone steel tooth bit with enhancements in cutter shape and

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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Kingwood, TX, United States of America

Dennis Cisneros