Roller Cone Drill Bits With Enhanced Cutting Elements And Cutting Structures

• US 20070125579A1
• Filed: 02/06/2007
• Published: 06/07/2007
• Est. Priority Date: 08/31/1998
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Chen, Shilin, Dahlem, James
• Granted Patent: US 7,497,281 B2
• Time in Patent Office: Days
• US Class Current: 175/374
• CPC Class Codes: E21B 10/08 Roller bits E21B10/26 takes precedence; roller core bits E21B10/06; characterised by wear resisting parts E21B10/50
• CPC Class Codes: E21B 10/16 characterised by tooth form or arrangement
• CPC Class Codes: E21B 10/50 the bit being of roller type

Abstract

Roller cone drill bits are provided with cutting elements and cutting structures optimized for efficient drilling of soft and medium formations interspersed with hard stringers. The cutting elements and cutting structures may be satisfactorily used to drill downhole formations with varying amounts of hardness. The cutting elements and cutting structures may also be optimized to reduce tracking and increase wear resistance.

Claims

1. A roller cone drill bit comprising:

a bit body having at least one support arm extending therefrom;

a respective cone assembly rotatably mounted on each support arm for engagement with a subterranean formation to form a wellbore;

each cone assembly having at least one row of cutting elements;

each cutting element having a crest extending from the respective cone assembly;

each cutting element having a first portion and a second portion with the associated crest disposed therebetween;

the first portion of the at least one cutting element having a relatively greater concentration of hard material; and

the second portion of the at least one cutting element having a reduced concentration of hard material as compared with the first portion of the at least one cutting element.

2. The drill bit of claim 1 further comprising the first portion of the at least one cutting element corresponding with a leading portion of the at least one cutting element.

3. The drill bit of claim 1 further comprising the first portion of the at least one cutting element corresponding with a trailing portion of the at least one cutting element.

4. The drill bit of claim 1 further comprising the cutting elements selected from the group consisting of inserts and milled teeth.

5. The drill bit of claim 1 further comprising the relatively hard material selected from the group consisting of polycrystalline diamond, tungsten carbide, metal borides, metal oxides, metal carbides and metal nitrides.

6. The drill bit of claim 1 further comprising a leading portion of the at least one cutting element having the reduced concentration of hard material and a trailing portion of the at least one cutting element having the greater concentration of hard material resulting in the at least one cutting element being self sharpening.

7. A roller cone drill bit comprising:

a bit body having at least one support arm extending therefrom;

a respective cone assembly rotatably mounted on each support arm for engagement with a subterranean formation to form a wellbore;

each cone assembly having at least one row of milled teeth;

each milled tooth having a crest extending from the associated cone assembly for engagement with adjacent portions of the formation;

each milled tooth having a leading portion and a trailing portion;

relatively hard material disposed on the trailing portion of each milled tooth; and

relatively soft materials forming the leading portion of each milled tooth resulting in self sharpening of each milled tooth.

8. A roller cone drill bit comprising:

a bit body having at least one support arm extending therefrom;

a respective cone assembly rotatably mounted on each support arm for engagement with a subterranean formation to form a wellbore;

each cone assembly having at least one row of inserts;

each insert having a crest extending from the associated cone assembly for engagement with adjacent portions of the formation;

each insert having a leading portion and a trailing portion;

relatively hard material disposed on the trailing portion of each insert; and

relatively soft materials forming the leading portion of each insert resulting in self sharpening of each insert.

9. A roller cone drill bit comprising:

a bit body having at least one support arm extending therefrom;

a respective cone assembly rotatably mounted on each support arm for engagement with a subterranean formation to form a wellbore;

each cone assembly having at least one row of inserts;

each insert having a crest extending from the associated cone assembly for engagement with adjacent portions of the formation;

each cone assembly and associated inserts having a scraping direction for optimum removal of formation materials;

each insert having a leading edge and a trailing edge defined in part by impact with a formation;

at least one insert having a first portion and a second portion; and

the first portion of the at least one insert formed from relatively hard materials as compared with materials used to form the second portion.

10. The drill bit of claim 9 further comprising the first portion of the at least one insert disposed adjacent to the associated leading edge.

11. The rotary cone drill bit of claim 9 further comprising the first portion of the at least one insert disposed adjacent to the associated trailing edge.

12. The drill bit or claim 9 further comprising the relatively hard material selected from the group consisting of polycrystalline diamond, tungsten carbide, metal borides, metal oxides, metal carbides and metal nitride.

13. The drill bit of claim 9 further comprising:

respective crests of inserts disposed in a gauge row of at least one cone assembly arranged generally perpendicular to an associated scraping direction;

respective crests of inserts disposed in a second row of cutting elements of the at least one cone assembly arranged generally parallel to the associated scraping direction; and

respective crests of inserts disposed in a third row of cutting elements oriented generally perpendicular to the associated scraping direction.

14. The drill bit of claim 9 further comprising:

three support arms extending from the bit body;

first, second and third cone assemblies rotatably mounted on respective support arms;

the respective crest for each insert in a gauge row of the first cone assembly oriented generally perpendicular to the associated scraping direction;

the respective crest for each insert in a gauge row of the second cone assembly oriented generally parallel to the associated scraping direction; and

the respective crest of each insert in a gauge row of the third cone assembly arranged in an alternating pattern defined in part by the crest of one of the inserts oriented generally perpendicular to the associated scraping direction and the crest of the adjacent inserts oriented generally parallel to the associated scraping direction.

15. A roller cone drill bit further comprising:

a bit body having at least one support arm extending therefrom;

a respective cone assembly rotatably mounted on each support arm for engagement with a subterranean formation to form a wellbore;

each cone assembly having at least a first row of inserts and a second row of inserts;

each cone assembly having both relatively smaller inserts and larger inserts;

each cone assembly having a smaller number of the larger inserts oriented for formation materials; and

each cone assembly having a larger number of the relatively smaller inserts oriented for enhanced penetration and crushing a formation.

16. A method for forming a roller cone drill bit comprising;

forming a bit body with at least three support arms extending therefrom;

forming a respective cone assembly operable to be rotatably mounted on each support arm;

forming a plurality of inserts with each insert having a respective leading portion and trailing portion; and

forming each insert with a greater concentration of hard material adjacent to the leading portion to provide enhanced resistance to abrasion and wear of the insert during contact with a formation.

17. The method claim 16 further comprising:

forming at least a first row of cutting elements and a second row of cutting elements on each cone assembly with a respective crest extending from each cutting element for engagement with adjacent portions of the formation;

orienting the crest of cutting elements in the first row generally perpendicular relative to an optimum scraping direction for removal of formation materials by the cutting elements of the first row;

orienting the crest of cutting elements in the second row in a direction generally parallel with the optimum scraping direction to enhance penetration of the formation by the cutting element of the second row; and

the leading portion of each insert with the greater concentration of hard materials making initial contact with the formation.

18. A method of forming a roller cone drill bit comprising:

forming a bit body with at least three support arms extending therefrom;

forming a respective cone assembly operable to be rotatably mounted on each support arm;

forming each cone assembly with a plurality of relatively small inserts and a plurality of larger inserts;

forming both the smaller inserts and the larger inserts with a respective crest extending from the respective cone assembly;

orienting the respective crests of a larger number of the relatively smaller inserts for enhanced penetration and crushing of a formation; and

orienting the respective crests of a smaller number of the larger inserts for optimum removal of formation materials.

19. The method of claim 18 further comprising:

forming a first row of inserts and a second row of inserts on each cone assembly with a respective crest extending from each insert for engagement with adjacent portions of the formation;

orienting the crest of the cutting elements of the smaller inserts generally perpendicular relative to an optimum scraping direction for removal of formation materials by the larger cutting elements; and

orienting the crest of the smaller cutting elements in a direction generally parallel with the scraping direction to enhance penetration of the formation by the relatively smaller cutting elements.