Roller cone drill bits with enhanced cutting elements and cutting structures
First Claim
Patent Images
1. A roller cone drill bit for forming a wellbore in a subterranean formation 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 the formation to form the wellbore;
each cone assembly having at least one row of cutting elements;
each cutting element having a crest extending from the associated cone assembly for engagement with adjacent portions of the formation;
each cone assembly and associated cutting elements having a scraping direction for optimum removal of formation materials;
the crests of the cutting elements in the at least one row arranged with the crest of a first cutting element oriented generally perpendicular relative to the scraping direction to optimize volume removal of formation material by the first cutting element;
a second cutting element in the at least one row disposed adjacent to the first cutting element;
the crest of the second cutting element oriented generally perpendicular relative to the crest of the first cutting element to optimize penetration of the formation by the second cutting element; and
the remaining cutting elements in the at least one row arranged in an alternating pattern with the crest of one cutting element aligned for optimum volume removal of formation material and the crest of an adjacent cutting element aligned for optimum penetration of the formation.
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Accused Products
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.
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Citations
30 Claims
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1. A roller cone drill bit for forming a wellbore in a subterranean formation comprising:
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a bit body having at least one support arm extending therefrom;
a respective cone assembly rotatably mounted on each support arm for engagement with the formation to form the wellbore;
each cone assembly having at least one row of cutting elements;
each cutting element having a crest extending from the associated cone assembly for engagement with adjacent portions of the formation;
each cone assembly and associated cutting elements having a scraping direction for optimum removal of formation materials;
the crests of the cutting elements in the at least one row arranged with the crest of a first cutting element oriented generally perpendicular relative to the scraping direction to optimize volume removal of formation material by the first cutting element;
a second cutting element in the at least one row disposed adjacent to the first cutting element;
the crest of the second cutting element oriented generally perpendicular relative to the crest of the first cutting element to optimize penetration of the formation by the second cutting element; and
the remaining cutting elements in the at least one row arranged in an alternating pattern with the crest of one cutting element aligned for optimum volume removal of formation material and the crest of an adjacent cutting element aligned for optimum penetration of the formation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A roller cone drill bit operable to form a wellbore in a subterranean formation comprising:
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a bit body having at least one support arm extending therefrom;
a respective cone assembly rotatably mounted on each support arm for engagement with the formation to form the wellbore;
each cone assembly having at least a gauge row of cutting elements, a second row of cutting elements and a third row of cutting elements spaced from each other;
each cutting element having a crest extending from the associated cone assembly for engagement with adjacent portions of the formation;
the respective crests of the cutting elements in the gauge row of at least one cone assembly arranged generally perpendicular to an associated scraping direction;
the respective crests of the cutting elements in the second row of cutting elements of the at least one cone assembly arranged generally parallel to the associated scraping direction; and
the respective crests of the cutting elements in the third row of cutting elements oriented generally perpendicular to the associated scraping direction. - View Dependent Claims (14)
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15. A roller cone drill bit comprising:
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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 cutting elements and a second row of cutting elements;
each cutting element having a crest extending from the associated cone assembly for engagement with adjacent portions of the formation;
each cone assembly and associated cutting elements having respective scraping directions for optimum removal of formation materials;
the crests of the cutting elements in the first row oriented generally perpendicular relative to the optimum scraping direction for removal of formation materials by the cutting element of the first row; and
the crests of the cutting elements in the second row oriented generally parallel relative to the optimum scraping direction for removal of formation materials by the cutting elements in the second row. - View Dependent Claims (16, 17)
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18. A roller cone drill bit comprising:
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a bit body having at least three support arms 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 a gauge row of cutting elements;
each cutting element having a crest extending from the respective cone assembly for engagement with adjacent portions of the formation;
each cone assembly and associated cutting elements having an optimum scraping direction for removal of formation materials;
the crest of the cutting elements in the gauge row of the first cone assembly oriented generally perpendicular relative to the optimum scraping direction for removal of formation materials by the gauge row of the first cone assembly;
the crests of the cutting elements in the gauge row of the second cone assembly oriented generally parallel relative to an optimum scraping direction to enhance penetration of the formation by the gauge row of the second cone assembly;
the crests of the cutting elements of the gauge row of the third cone assembly arranged with the crest of a first cutting element oriented generally perpendicular relative to the optimum scraping direction for removal of the formation materials and the crest of a second cutting element in the gauge row of the third cone assembly disposed approximately perpendicular to the crest of the first cutting element to enhance penetration of the formation; and
the remaining cutting elements in the gauge row of the third cone assembly arranged in an alternating pattern with the crest of one cutting element aligned for optimum removal of formation materials and the crest of an adjacent cutting element aligned for enhanced penetration of the formation. - View Dependent Claims (19, 20, 21, 22)
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23. A roller cone drill bit comprising:
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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;
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 material; and
the second portion of the at least one insert formed from material having a reduced hardness as compared with the first portion of the at least one insert. - View Dependent Claims (24, 25)
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26. A method for forming a roller cone drill bit operable to drill a wellbore in soft formations and medium formations interspersed with hard stringers comprising:
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forming a bit body with at least one support arm extending therefrom;
rotatably mounting a cone assembly on each support arm;
forming at least one row of cutting elements on each cone assembly with a respective crest extending from each cutting element for engagement with adjacent portions of a formation;
orienting the crest of at least one cutting element generally perpendicular relative to an optimum scraping direction for removal of formation materials by the cutting element;
orienting the crest of an adjacent cutting element in a direction generally parallel with the optimum scraping direction to enhance penetration of the formation by the cutting element; and
selecting the number of cutting elements with crests oriented for penetration of the formation and the number of cutting elements with crests oriented for removal of formation materials to optimize downhole drilling efficiency of the drill bit. - View Dependent Claims (30)
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27. A method for forming a roller cone drill bit to drill a wellbore in a mixed formation of soft material and hard material comprising;
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forming a bit body with at least three support arms extending therefrom;
rotatably mounting a cone assembly on each support arm;
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 mixed 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
selecting the number of cutting elements with crests oriented for removal of formation materials and the number of cutting elements with crests oriented for penetration of the formation to optimize downhole drilling efficiency of the drill bit.
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28. A roller cone drill bit comprising:
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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 cone assembly and associated milled teeth having a scraping direction for optimum removal of formation materials;
each milled tooth having a leading edge and a trailing edge;
each milled tooth having at least a first portion and a second portion;
the first portion of each milled tooth formed from relatively hard material; and
the second portion of each milled tooth formed from material having a reduced hardness as compared with the first portion of the respective milled tooth. - View Dependent Claims (29)
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Specification