US3915246A

US3915246A - Rotary drilling bit

Info

Publication number: US3915246A
Application number: US470519A
Authority: US
Inventors: Adel E Sheshtawy
Original assignee: Individual
Current assignee: TRI-MAX Corp A CORP OF DE
Priority date: 1974-05-16
Filing date: 1974-05-16
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28

Abstract

The specification discloses a rotary drill bit having a drill body with a full gauge upper stabilizer section and an intermediate taper section tapering to a reduced diameter from the stabilizer section. The drill body further includes a lower nose section extending downwardly from the reduced diameter of the taper section. A plurality of vertical grooves are spaced apart about the body and extend from the nose section to the stabilizer section for allowing upward flow of rock cut by the nose section. The width of the vertical groove increases from the nose section to the stabilizer section. A plurality of spaced apart transverse grooves extend around the body to provide stress relief areas to assist in rock failure and to insure proper cleaning of the cutting edge of the bit. The vertical and transverse grooves intersect to provide generally rectangular areas over the body. There is an arrangement of the jet apertures in the body. A plurality of discrete cutting members extend outwardly from the rectangular areas. A set of the cutting members are arranged about the surface of the body in a generally helical spiral and extend outwardly further from the surface of the body than the remainder of the cutting members. The specification further discloses one embodiment of the invention including smaller jet apertures in the body and a valve to prevent bouyancy of the bit during lowering of the bit and to allow draining of fluid from the bit prior to raising the bit.

Description

United States Patent 1 Sheshtawy ROTARY DRILLING BIT [76] Inventor: Adel E. Sheshtawy, 300 W.

Grauwyler Road, Irving, Tex. 75060 22 Filed: May 16, 1974 21 Appl. No.: 470,519

[52] US. Cl 175/317; 175/410 [51] Int. Cl. E21B 27/00; E21B 13/01 [58] Field of Search 175/317, 318, 394, 410, 175/417 [56] References Cited UNITED STATES PATENTS 2,371,489 3/1945 Williams, Jr. 175/329 3,158,216 11/1964 Baron et a1. 175/410 3,583,504 6/1971 Aalund 175/410 3,688,853 9/1972 Maurer et al.... 175/340 3,800,892 4/1974 Fischer 175/410 R25,319 H1963 Short 175/329 FOREIGN PATENTS OR APPLICATIONS 237,071 12/1969 U.S.S.R 175/329 Primary Examiner-James A. Leppink Attorney, Agent, or F irmRichards, Harris & Medlock [57] ABSTRACT The specification discloses a rotary drill bit having a Oct. 28, 1975 drill body with a full gauge upper stabilizer section and an intermediate taper section tapering to a reduced diameter from the stabilizer section. The drill body further includes a lower nose section extending downwardly from the reduced diameter of the taper section. A plurality of vertical grooves are spaced apart about the body and extend from the nose section to the stabilizer section for allowing upward flow of rock cut by the nose section. The width of the vertical groove increases from the nose section to the stabilizer section. A plurality of spaced apart transverse grooves extend around the body to provide stress relief areas to assist in rock failure and to insure proper cleaning of the cutting edge of the bit. The vertical and transverse grooves intersect to provide generally rectangular areas over the body. There is an arrangement of the jet apertures in the body. A plurality of discrete cutting members extend outwardly from the rectangular areas. A set of the cutting members are arranged about the surface of the body in a generally helical spiral and extend outwardly further from the surface of the body than the remainder of the cutting members. The specification further discloses one embodiment of the invention including smaller jet apertures in the body and a valve to prevent bouyancy of the bit during lowering of the bit and to allow draining of fluid from the bit prior to raising the bit.

16 Claims, 6 Drawing Figures US. Patent Oct. 28, 1975 Sheet 1 0f2 "I 2 I i? 1 I 3 Q CIQQQQ 00 I g L. GOO 7Qfii 44 US. Patent Oct. 28, 1975 Sheet 2 of2 3,915,246

FIG. 6

ROTARY DRILLING BIT FIELD OF THE INVENTION This invention relates to earth drilling tools and more particularly relates to a rotary drill bit for drilling oil wells, gas wells and the like. I

THE PRIOR ART In an effort to supply the increasing demand for energy, the petroleum industry is presently drilling deeper than ever before in the earths strata. However, it has been found that an unproportional increase in drilling costs relative to increased depth of drilling has occurred primarily to problems in drill bit performance. For example, conventional rotary drill bits, such as three cone rotary drill bits and the like, often have very short life due to either teeth or bearing failure. Moreover, such conventional rotaty drilling bits often have limited load carrying capacity and consequently limited drilling rates. Previously developed rotary drilling bits also have relatively low efficiency of energy transmission for rock breakage and have thus generally provided relatively poor performance at greater depths.

The introduction of tungston carbide inserts' and journal bearings to rotary drilling bits has not completely overcome the aforementioned bit performance limitations. The addition of diamond drilling bits have been utilized to provide increased performance, but the diamond bits have a high initial cost and a damaging effect on the drill string due to the excessive torque produced by the operation of the bits.

A need has thus arisen for an improved rotary drill bit which does not require bearings which often cause conventional tricone bit failure. Such an improved rotary drill bit should not only improve deep drilling efficiency, but would also desirably eliminate the excessively high torque in a drilling string heretofore associated with drill bits such as the diamond bit.

SUMMARY OF THE INVENTION In accordance with the present invention, an improved rotary drill bit is provided which substantially eliminates or reduces the problems heretofore associated with previously developed bits, and which not only eliminates excessive bit failure and excessively high torque, but which provides improved cutting efficiency and operation.

In accordance with the present invention, a drill bit includes a body member having structure for connection to the lower end of a rotary drill string. A plurality of cutting members extend outwardly from the surface of the body member. A set of the cutting members are arranged about the surface of the body member in a generally helical spiral and extend outwardly further from the surface of the body member than the remainder of the cutting members.

In accordance with another aspect of the invention, a rotary drill bit is provided which includes a drill body having a full gauge upper stabilizer section and an intermediate taper section tapering to a reduced diameter from the stabilizer section. The drill body further includes a lower curved nose section. A plurality of vertical grooves are spaced apart about the body and extend from the nose section to the stabilizer section for allowing upward flow of rock cut by the nose section. A plurality of spaced apart transverse grooves extend about the body to provide stress relief areas to assist in rock failure. The vertical and transverse grooves intersect to provide generaly rectangular areas over the body. A plurality of discrete cutting members extend outwardly from the rectangular areas.

In accordance with a more specific aspect of the invention, a rotary drill bit is provided with a drill body having a plurality of vertical grooves spaced apart about the body and extending along the length thereof. The vertical grooves increase in width from the lower portion of the body to the upper portion. A plurality of spaced apart transverse grooves extend around the body, the transverse grooves increasing in width from the lower portion of the body to the upper portion of the body. Discrete cutting elements are disposed along one side of the vertical grooves to provide a cutting edge along the grooves. Jet apertures are disposed in the lower portion of the bit and are suitably located close to the formation being drilled in order to maximize the hydraulic forces acting upon the formation.

DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and for further objects and advantages thereof, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevation view of the rotary drill bit of the invention;

FIG. 2 is an enlarged portion of an area of the drill bit shown in FIG. 1 illustrating different sizes of the dis-. crete cutting members of the bit;

FIG. 3 is a sectional view of thebit shown in FIG. 1 taken generally along the section lines 33;

FIG. 4 is a sectional view of the drill bit taken generally along the section lines 44 in FIG. 3;

FIG. 5 is a diagram of a second embodiment of the present drill bit; and

FIG. 6 is a make-and-break housing for attachment to the drill bit shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a drill bit body 10 includes a threaded collar 12 for connection to a conventional drill string. Body 10 is comprised of three basic portions including an upper full gauge stabilizer portion identified generally by the numeral 14, an intermediate taper section 16 and a lower nose section 18. The full gauge stabilizer section is approximately equivalent in diameter at its uppermost portion to the hole diameter to be drilled. A slight taper is provided in the lower portion of the stabilizer section to prevent excess loading of the cutting edges of the bit. The stabilizer section thus insures a full gauge hole while preventing hole deviation.

The taper section tapers downwardly from the stabilizer section in a generally linear manner to a reduced diameter 20. The taper section permits the contact of the cutting edges of the bit with the formation to be drilled and allows the positioning of the fluid jet apertures 22 very close to the formation to be drilled in order to maximize the hydraulic forces acting on the rock. In addition, the jet apertures 22 may be oriented at any desired geometry to assist in rock cutting and removal of particular types of formations. The sides of the taper section 16 are substantially linear and the taper angle of the taper section will depend upon the formation type to be drilled.

The nose section 18 has a lower central portion 24 which may be pointed, rounded, elliptical or flat, but is configured to permit the concentration of load on the centralized area of the bit. The upper portion of the nose section may be generally linear or concave and extends upwardly to the reduced diameter 20 in order to provide initial stabilization to the bit and to prevent its deviation from the hole course.

Although it will be understood that angles of the sides of the present bit may be varied to meet various drilling condidtions, in one embodiment of the invention the lower part of the stabilizing section of the bit was tapered inwardly at approximately from vertical. The taper section 16 was tapered inwardly at approximately 60 from the vertical, while the nose section 18 was tapered inwardly at approximately 85 from vertical.

An important aspect of the bit 10 are a plurality of vertical grooves 26 which are spaced about the periphery of the bit. The grooves 26 increase in width from the nose section to the stabilizer section and are generally concave in cross section, as best illustrated in FIG. 3. The vertical grooves 26 provide a cutting flow from the bottom of the hole during drilling operations in order to expose new rock surfaces for the cutting edges of the bit. Grooves 26 may be straight or may be curved in the direction of bit rotation.

Another important aspect of the present invention is the provision of horizontal or transverse circular grooves 28 which are spaced apart about the body of the bit. The transverse grooves 28 are semicircular in cross section and the widths of the grooves 28 increase as the grooves are positioined closer to the stabilizer section 14. The transverse grooves provide stress relief openings in order to accommodate and encourage rock failure during drilling operations. In addition, the transverse grooves 28 insure proper cleaning of the cutting edges of the bit from the rock being cut. The transverse relief grooves 28 thus eliminate compression and allow the rock to move and fail in tension and shear, thereby assisting in cutting operations and removal of the rock upwardly through the grooves 26.

The vertical grooves 26 and transverse grooves 28 intersect to form a plurality of generally rectangular areas of various sizes over the entire body of the bit 10. A plurality of discrete cutting elements 30 are disposed over the rectangular areas. In the preferred embodiment, the cutting elements may be either milled teeth, tungston carbide inserts, hard ceramic inserts or diamonds. The cutting elements are mounted on the body 10 so as to be perpendicular to the rock at the point of contact. As may be seen in the Drawings, the

cutting elements are provided with different sizes and with different spacings throughout the rectangular areas.

An important aspect of the invention is that certain of the cutting elements are provided with different heights than the remainder of the cutting elements. Referring to FIG. 1, a pair of dotted lines 34 may be seen to be helically disposed about the body 10 in the direction of rotation of the bit. The cutting elements adjacent the dotted lines 34ab are provided with an increased height from the remainder of the cutting elements in order to assist the advance of the bit with a minimum of required thrust. In a preferred embodiment, the cutting elements along the spiral lines 34 were provided with 1/32 inch greater height than the remainder of the elements 30. FIG. 2 is an enlarged view of a portion of the bit 10 and illustrates how the cutting elements 30a disposed in the region of the dotted spiral lines 34ab have a graeter height than the cutting elements 30b.

FIG. 3 illustrates another important aspect of the invention in that cutting elements 36 are disposed along one edge of the vertical groove 26 in order to assist in cutting. The cutting elements 36 are disposed so as to move against the rock in the direction of rotation of the bit. FIG. 3 also illustrates the central aperture 40 which extends through the bit 10 and which is best illustrated with reference to FIG. 4.

Another aspect of the invention is that the cutting elements 30 formed on the nose section 18 are somewhat smaller in size than the cutting elements on the remainder of the body. In addition, an increased number of cutting elements are concentrated in the nose section and are provided with different angles of inclination in order to cut at various radii during rotation of the bit. As the nose section of the bit is the weakest portion of the bit and is subject to the greatest stress during cutting, it is important to provide a number of cutting elements at the nose section in order to cut the core and remove the core as fast as possible.

Referring to FIG. 4, it will be seen that the aperture 40 is narrower at the upper portion of the bit 10 than at the lower chamber 42. A plurality of jet aperture channels 44 are formed from the chamber 42 and ex- .tend to the jet apertures 22. The number and orientation of the jet apertures 22 will be chosen according to the character of the formation being drilled. 1n the preferred embodiment, six jet apertures are provided in the positions illustrated.

The present drill bit may be utilized for conventional drilling at conventional speeds and with conventional pressures of drilling fluid applied. However, the present bit may also be utilized for high pressure jet drilling wherein very high pressures, in the range of from 10,000 to 20,000 psi, of drilling fluid pressure are provided. When the present bit is utilized for high pressure drilling, nozzle members 46 are disposed in each of the channels 44. Each of the nozzle members 46 is provided with a streamlined parabolic opening in order to provide a high pressure stream of fluid through the jet apertures 22. The jet members 46 are provided with 0- rings in order to provide sealing and are maintained in place by snap rings, not shown. When the drill bit is utilized for conventional drilling pressures, the greater diameter jet members 46 are utilized.

For a description of high pressure jet drilling, refer ence is made to the article entitled A Laboratory Study of High Pressure Fluid Jet Drilling, by Sheshtawy and Kennedy, Paper No. SPE 4520, published in 1973 by The American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., and presented in the 48th Annual Fall Meeting of the Society of Petroleum Engineers of A.I.M.E., Sept. 30-Oct. 3, 1973.

FIG. 4 illustrates how the cutting elements 30 are inserted and maintained in position within the body 10. FIG. 4 also illustrates the use of a valve which is necessary when the present bit is utilized as a high pressure drilling bit due to the small size of the jet members 46. The valve includes a valve stem 50 which is movable within a housing 52 sealingly lodged within the nose section 18. A seat 54 limits the upward movement of the valve 50, and the tapered shape of the valve 50 and the aperture through the housing 52 limits the downward movement of the valve 50. A shaft 56 extends from the valve 50 and includes a helical coil spring 58 disposed thereabout and biased against the valve 50 and a support member 60. A tripping ball 62 is movable in response to pressure from the jet fluid in order to bear against a conical portion 64 of the shaft 56. Apertures 65 are provided in the conical member 64, which acts as a screen to prevent jet plugging. The tripping action for the system may also be achieved by heavy metallic bar structure if desired.

In operation of the valve assembly illustrated in FIG. 4, when the bit is being lowered into the borehole, the valve is opened in order to insure the fillup of the inside of the drill bit and the drill pipe to prevent bouyancy of the bit and string. The valve 50 will be pushed upwardly against the spring 58 by the difference in hydrostatic head between the empty drill string and the fluid in the hole. The upper seat 54 will permit the flow of fluid inside the drill bit and drill string and will prevent forward upward movement of the valve 52. When the bit reaches the bottom of the hole, the string 58, together with the circulation pressure of the drill fluid, will seal tightly the valve 50 against the lower seat formed in the housing 52.

To assist in allowing the fluid to drain from the bit and drill string before pulling the bit out of the hole, the tripping ball 62, along with the fluid pressure, will move the valve shaft 54 and valve 50 including the housing 52 downwardly such that the valve 50 impinges upon upwardly extending fingers 66. Fingers 66 thus lift the valve 50 relative to the housing 52, thereby unseating the valve 50 and allowing the flow of fluid from the valve string outwardly through the jet nozzle apertures 22.

When the bit is utilized as a conventional rotary bit, the valve assembly shown in FIG. 4 is not required due to the increased aperture size of the jet nozzles 46.

FIGS. 5 and 6 illustrate another embodiment of the present rotary drill bit. Referring to FIG.. 5, the drill bit is identical to the drill bit illustrated in FIGS. 1-4, and is therefore illustrated in dotted lines. In this embodiment, a shank 68 is provided between the main drill body 10 and the collar 12. A key slot 70 is provided in the shank 68. While it will be understood that diameters of the bit may be varied, in the preferred embodiment the collar 68 is provided with 0.8 the diameter of the largest diameter of the main body 10.

FIG. 6 illustrates a make-and-break block assembly including two

body halves

72 and 74 hinged together by a hinge 76. Each of the body halves 72 and 74 are included with

semicircular cutout portions

76 and 78, with outwardly extending

keys

80 and 82. In operation, the

halves

72 and 74 are open by movement about the hinge 76 and are placed about the collar 68. The

keys

80 and 82 are received within the key slots 70 in the collar 68 and the bit is firmly attached to the make-andbreak block assembly in order to easily connect the bit to the drill string.

Whereas the present invention has been described with respect to specific embodiments thereof, it will be understood that various changes and modifications will be suggested to one skilled in the art, and it is intended to encompass such changes and modifications as fall within the scope of the appended claims.

What is claimed is:

a plurality of vertical grooves spaced apart about said I body and extending fromgsaid nose section to said stabilizer section for allowing upward flow of. rock cut by said nose section,

a plurality of spaced apart transverse grooves extending around said body to provide stress relief areas to assist in rock failure,

said vertical and transverse grooves intersecting to provide generally rectangular areas .over said body, the width of said rectangular areas being substantially greater than the width of said vertical grooves such that the majority of the surface area of said drill body comprises cutting surfaces, and

a plurality of discrete cutting members extending outwardly from said rectangular areas.

2. The drill bit of claim 1 and further comprising:

an increased density of said cutting members being disposed on said outwardly curved nose section.

3. The drill bit of claim 1 wherein said vertical grooves increase in width from said nose section to said stabilizer section.

4. The drill bit of claim 1 wherein the width of said transverse grooves disposed adjacent said stabilizer section is greater than the width of said transverse grooves disposed adjacent said nose section.

5. The drill bit of claim 1 wherein the cross section of said grooves is semi-circular.

6. The drill bit of claim 1 wherein said cutting members have different sizes and are disposed with varying densities on ones of said rectangular areas.

7. The drill bit of claim 1 and further comprising:

discrete cutting members disposed on the following sides of said vertical grooves.

8. The drill bit of claim 1 wherein ones of said cutting members are disposed about a spiral path over said body member and are longer than the remainder of said cutting members.

9. A drill bit comprising:

a body member having means for connection to the lower end of a rotary drill string,

a plurality of cutting members extending outwardly from the surface of said body member,

a set of said cutting members extending outwardly further from the surface of said body member than the remainder of said cutting members, said set of cutting members being arranged around the surface of said body member in a generally helical spiral.

10. The drill bit of claim 9 and further comprising:

vertical and transverse grooves extending over said body member to form rectangular areas over said body member, said cutting members formed on said rectangular areas.

1 1. The drill bit of claim 9 wherein said cutting members have different sizes and are disposed over said body member in different densities.

12. A rotary jet drill comprising:

said body member tapering downwardly from'a full gauge stabilizer section to a narrow outwardly curved nose section to form a triangular side configuration,

a central opening through said bit communicating with a plurality of jet apertures formed in the exterior of said body member between said stabilizer and nose sections,

a plurality of vertical grooves extending between said stabilizer and nose sections and increasing in width from said nose section to said stabilizer section,

a plurality of circular transverse grooves formed about said body member, the width of said transverse grooves adjacent said stabilizer section being greater than the width of said transverse grooves adjacent said nose section, and

discrete cutting members disposed on said body member between said grooves.

13. The drill bit of claim 12 and further comprising:

high pressure jet nozzles mounted in said jet apertures.

14. The drill bit of claim 12 and further comprising:

valve means mounted in said nose section for allowing fluid to enter said drill string when said bit is being lowered and for allowing fluid to drain from said drill string when said bit is being raised.

15. The drill bit of claim 12 and further comprising:

a shank disposed on the upper end of said bit,

key slots being formed in said shank, and

block means having keys for interfitting about said shank for connecting said bit to the drill string.

16. A rotary jet drill bit comprising:

said body member tapering downwardly from a full gauge stabilizer section to a narrow outwardly curved nose section to form a triangular side configuration,

a central opening through said bit communicating with a pluralilty of jet apertures formed in the exterior of said body member between said stabilizer and nose sections,

a plurality of circular transverse grooves formed about said body member, the width of said trans: verse grooves adjacent said stabilizer section being greater than the width of said transverse grooves adjacent said nose section,

discrete cutting members disposed on said body member between said grooves, and

ones of said cutting members being disposed in a spiral about said body members and having increased lengths.

Claims

1. A rotary drill bit comprising: a drill body having a full gauge upper stabilizer section and an intermediate taper section tapering to a reduced diameter from said stabilizer section, said intermediate taper section extending along a significant portion of the length of said body such that the side view of said body has the general configuration of an inverted triangle, said drill body further including a lower outwardly curved nose section, a plurality of vertical grooves spaced apart about said body and extending from said nose section to said stabilizer section for allowing upward flow of rock cut by said nose section, a plurality of spaced apart transverse grOoves extending around said body to provide stress relief areas to assist in rock failure, said vertical and transverse grooves intersecting to provide generally rectangular areas over said body, the width of said rectangular areas being substantially greater than the width of said vertical grooves such that the majority of the surface area of said drill body comprises cutting surfaces, and a plurality of discrete cutting members extending outwardly from said rectangular areas.

2. The drill bit of claim 1 and further comprising: an increased density of said cutting members being disposed on said outwardly curved nose section.

7. The drill bit of claim 1 and further comprising: discrete cutting members disposed on the following sides of said vertical grooves.

9. A drill bit comprising: a body member having means for connection to the lower end of a rotary drill string, a plurality of cutting members extending outwardly from the surface of said body member, a set of said cutting members extending outwardly further from the surface of said body member than the remainder of said cutting members, said set of cutting members being arranged around the surface of said body member in a generally helical spiral.

10. The drill bit of claim 9 and further comprising: vertical and transverse grooves extending over said body member to form rectangular areas over said body member, said cutting members formed on said rectangular areas.

11. The drill bit of claim 9 wherein said cutting members have different sizes and are disposed over said body member in different densities.

12. A rotary jet drill comprising: a body member having means for connection to the lower end of a rotary drill string, said body member tapering downwardly from a full gauge stabilizer section to a narrow outwardly curved nose section to form a triangular side configuration, a central opening through said bit communicating with a plurality of jet apertures formed in the exterior of said body member between said stabilizer and nose sections, a plurality of vertical grooves extending between said stabilizer and nose sections and increasing in width from said nose section to said stabilizer section, a plurality of circular transverse grooves formed about said body member, the width of said transverse grooves adjacent said stabilizer section being greater than the width of said transverse grooves adjacent said nose section, and discrete cutting members disposed on said body member between said grooves.

13. The drill bit of claim 12 and further comprising: high pressure jet nozzles mounted in said jet apertures.

14. The drill bit of claim 12 and further comprising: valve means mounted in said nose section for allowing fluid to enter said drill string when said bit is being lowered and for allowing fluid to drain from said drill string when said bit is being raised.

15. The drill bit of claim 12 and further comprising: a shank disposed on the upper end of said bit, key slots being formed in said shank, and block means having keys for interfitting about said shank for connecting said bit to the drill string.

16. A rotary jet drill bit comprising: a body member having means for connection to the lower end of a rotary drill string, said body member tapering downwardly from a full gauge stabilizer section to a narrow outwardly curved nose section to form a triangular side configuration, a central opening through said bit communicating with a plurality of jet apertures formed in the exterior of said body member between said stabilizer and nose sections, a plurality of vertical grooves extending between said stabilizer and nose sections and increasing in width from said nose section to said stabilizer section, a plurality of circular transverse grooves formed about said body member, the width of said transverse grooves adjacent said stabilizer section being greater than the width of said transverse grooves adjacent said nose section, discrete cutting members disposed on said body member between said grooves, and ones of said cutting members being disposed in a spiral about said body members and having increased lengths.