Patent Application
20100108402
Downhole cutting tools commonly employ carbide cutters made of a solid piece of carbide. Although such cutters are effective at cutting the downhole materials they are designed to cut, their cutting efficiency, and effective lifespan, can be significantly reduced due to fracturing or chipping of the cutter. Fracturing and chipping can remove all or a portion of a cutting edge of the carbide cutter resulting in a dull and inefficient cutting tool. Well operators will therefore be receptive to tools and methods to increase the longevity of downhole cutters.
Disclosed herein is a downhole cutting tool. The tool includes, a body, a first contoured cutting element in operable communication with the body, and at least one contingency contoured cutting element in operable communication with the first contoured cutting element and the body. And a contour of the at least one contingency contoured cutting element substantially matching a contour of the first contoured cutting element, the at least one contingency contoured cutting element being maintainable in reserve and positioned to substitute for the first contoured cutting element if the first contoured cutting element becomes detached.
Further disclosed herein is a method of making a downhole cutter. The method includes, substantially matching a contoured cutting edge of at least one contingency contoured cutting element with a contoured cutting edge of a first contoured cutting element, and attaching the at least one contingency contoured cutting element adjacent the first contoured cutting element such that the at least one contingency contoured cutting element substitutes for the first contoured cutting element if the first contoured cutting element becomes detached.
Further disclosed herein is a downhole cutter. The cutter includes, a plurality of cutting elements having substantially matched contoured cutting edges, and a bonding material having greater ductility than the plurality of cutting elements bonding the plurality of cutting elements to one another in an arrangement such that detachment of one of the plurality of cutting elements reveals another of the substantially matched contoured cutting edges that substitutes for a contoured cutting edge of the detached cutting element.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
Referring to
In this particular embodiment, the bodies 18 can articulate from a position wherein the cutters 12 are positioned radially inwardly of a diameter 26 that defines the tubular 14, to a position wherein the cutters 12 (during rotation of the cutting tool 10) trace out a diameter 30 that is substantially larger than the diameter 26. It should be noted that alternate embodiments of the cutting tool 10 could have fixed bodies 18 as well. A characteristic of any embodiment of the cutting tool 10 is that the tool 10 can move in such a way as to force the cutter 12 and cutting elements 22A-22D, attached to the body 18, to contact and thereby cut into a material intended to be removed.
Referring to
Regardless of the bonding method used, the elements 22A-22D disclosed herein are made of a hard metal material such as tungsten carbide, titanium carbide or tantalum carbide, for example, or other hard material such as a ceramic (cubic boron nitride) or diamond. In embodiments disclosed herein the elements 22A-22D are made of tungsten carbide, also referred to as carbide. Carbide has exceptional hardness, a high melting point, and excellent wear characteristics when used as a cutting tool for cutting metal and earth formation materials. The elements 22A-22D, by design, are harder and more brittle than the bonding materials 54 employed and than the material of the body 18, which is made of a strong rigid material such as steel, for example. With the foregoing construction the more ductile bonding materials 54 and the body 18 will absorb much of the shock incurred while cutting. Should a load incurred be so great as to cause detachment of a portion of the cutter 12 the bonding material 54 should fail prior to fracture of one of the elements 22A-22D, thereby limiting the loss of a piece of the cutter 12 to that of an individual element 22A-22D. The foregoing construction thereby limits the loss of carbide volume from the cutter 12 due to each excessive load in comparison to a single solid piece cutter 12, for example. Additionally, should a fracture of an element 22A-22D occur the ductile bonding material 54 would prevent the fracture from propagating to an adjacent element 22A-22D, again limiting the size of a fracture chip to the size of an individual element 22A-22D.
Further, when, for example, the first element 22A of a stack 34 is detached at a bonding interface the contingent element 22B becomes exposed. And since the contingent element 22B has a contour 50B that substantially matches the contour 50A of the first element 22A, the contingent element 22B is positioned to substitute for and continue cutting of the target material. This substitution effect is possible because the first element 22A is displaced from the contingent element 22B in a direction according to arrow 58 (
Since each of the stacks 34 can have multiple contingent elements 22B-22D, with three contingent elements 22B-22D being illustrated in this embodiment, a new cutting edge 46B-46D can be reestablished several times without having to retrieve the tool 10.
While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
