Roller cone drill bits with enhanced cutting elements and cutting structures

• US 7,497,281 B2
• Filed: 02/06/2007
• Issued: 03/03/2009
• Est. Priority Date: 08/31/1998
• Status: Expired due to Term

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Dahlem, James S., Chen, Shilin
• Primary Examiner(s): DANG, HOANG C
• Application Number:
  US11/671,649
• Publication Number:
  US 20070125579A1
• Time in Patent Office: 756 Days
• Field of Search: 175/374, 175/376, 175/378
• 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;

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; and

at least one cone assembly wherein,

at least one row of cutting elements is oriented such that the crest of each cutting element is generally perpendicular to an associated scraping direction; and

at least another row of cutting elements is oriented such that the crest of each cutting element is generally parallel to the associated scraping direction.

2. 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 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;

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

at least one cone assembly wherein,

at least one row of inserts is oriented such that the crest of each insert is generally perpendicular to an associated scraping direction; and

at least another row of inserts is oriented such that the crest of each insert is generally parallel to the associated scraping direction.

8. The drill bit of claim 7 further comprising the first portion of the at least one insert disposed adjacent to the associated leading edge.

9. The rotary cone drill bit of claim 7 further comprising the first portion of the at least one insert disposed adjacent to the associated trailing edge.

10. The drill bit or claim 7 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.

11. 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;

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

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 cuffing 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.

12. A roller cone drill bit comprising:

a bit body having three 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 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;

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

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

a respective crest for each insert in a gauge row of the first cone assembly oriented generally perpendicular to an 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.

13. 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 longitudinal crest along with a respective leading portion and trailing portion;

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;

respective longitudinal crests of a portion of the cutting elements aligned generally parallel with an optimum scraping direction to enhance formation penetration whereby the leading portions of such cutting elements formed from hard material have an increased downhole drilling life; and

respective longitudinal crests of another portion of the cutting elements aligned generally perpendicular with an optimum scraping direction to enhance formation removal whereby the leading portions of such cutting elements formed from hard material have an increased downhole drilling life.

14. 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 a respective trailing portion;

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

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.