Patent Application
20120199395
1. Field of Invention
The invention is directed to cutting elements or “cutters” for cutting tools used to cut, abrade, or mill objects and, in particular, to cutting elements utilized in tools to cut objects within oil and gas wells, the cutting elements comprising a pre-formed fracture plane to facilitate breakage of the cutting element along a pre-determine location of the cutting element so that the cutting element can either continue to cut away an object in the wellbore, or so that the cutting element can be completely removed so that another cutting element disposed behind the fractured cutting element can begin cutting the object.
2. Description of Art
In the drilling, completion, and workover of oil and gas wells, it is common to perform work downhole in the wellbore with a tool that has some sort of cutting profile interfacing with a downhole structure. Examples would be milling a downhole metal object with a milling tool or cutting through a tubular with a cutting or milling tool. To facilitate these operations, cutting elements are disposed on the downhole cutting tool. In some instances, the cutting elements are stack one on top of another so that when the upper cutting element is worn or broken away, another cutting element can be exposed to the object in the well so that cutting can continue.
Broadly, the invention is directed to a cutting element disposed on a downhole cutting tool utilized in cutting away an object disposed within the well, wherein the cutting element comprises at least one pre-formed fracture plane to facilitate breaking away a portion of the cutting element so that the cutting element can continue to cut or abrade the object, or so that a second cutting element disposed behind the broken away cutting element can engage and cut the object. The term “object” encompasses any physical structure that is to be cut, abraded, or milled such as structures disposed within a well, for example, another tool that is stuck within the well, a bridge plug, the well tubing, the well casing, or the like.
In one particular embodiment, the cutting elements are disposed on blades of a downhole cutting tool that are disposed on a face of the tool. The blades are disposed on the face such that rotation of the tool causes rotation of the blades. In other embodiments, the cutting elements are disposed on an end of a mill or other cutting tool.
In one embodiment of the cutting element, the cutting element comprises a pre-formed fracture plane disposed on at least one surface of the cutting element. For example, in a specific embodiment the cutting element comprises a body having a cutting surface and a non-cutting surface wherein the non-cutting surface comprises a fracture plane disposed within the non-cutting surface. In one particular embodiment, the fracture plane comprises a groove cut into the non-cutting surface.
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to these embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
Referring now to
As shown in
Disposed within bottom surface 40 is at least one groove 44 providing fracture plane 48. In the embodiment of
Although apexes 45 are shown disposed directly below valleys 29, it is to be understood that the apexes 45 can be moved slightly to the left or right of valleys 29 and still provide the fracture plane 48. In addition, although grooves 44 are shown is V-shaped grooves having apexes 45, it is to be understood that grooves 44 can have any other shape, with or without apexes 45. For example, grooves 44 can comprise a rounded shape, concave or convex curved walls with an apex, and the like.
In the embodiment of
Although the dimensions of cutting element 10 can be modified as desired or necessary to facilitate locating cutting element 10 on the cutting tool to maximize the cutting ability of cutting element 10, in one particular embodiment, cutting element 10 comprises a width of 0.5 inches, a length of 0.5 inches, a height of 0.25 inches, a segment width of 0.07 inches, widths 25 measuring 0.1 inches, angle 28 measuring 166 degrees, angle 46 measuring 60 degrees, and groove depth 47 measuring 0.03 inches.
In operation, multiple cutting elements 10 are disposed on a cutting tool, such as on the blade of a cutting mill or directly on the end of the cutting tool. The cutting element is then contacted with an object to be cut, such as an object disposed within a wellbore. The cutting tool is then rotated causing the cutting elements to bite into the object and gradually cut, abrade, or mill away the object. During the cutting operations, one or more of the segments 23 of the cutting elements may hinder the cutting operations such as by causing the cutting tool to jump off of the object, or because the cutting profile has sufficiently worn down that the segment is no longer providing sufficient cutting action. In these situations, grooves 44 and, if present grooves 54 and/or grooves 64, provide a weak point along fracture plane 48 such that the cutting elements will break along a known path, i.e., fracture plane 48. Upon breaking, one of the segments 23 falls away while the remaining segment(s) continue to cut the object in the well until the object is completely cut away or until all of the segments break away from the cutting tool.
In certain embodiments, the cutting elements are stacked on top of one another so that when one cutting element completely breaks away, another cutting element is exposed to the object so that cutting can continue.
In one embodiment, fracture plane 48 of the cutting element is formed by grooves 44 that are disposed in bottom surface 40 by a laser or other similar device that melts and, thus, transforms, a portion of the material of the cutting element such that it is weaker than the remaining material forming the cutting element. Similarly, grooves 54, 64 can be disposed within side walls 50, 60, respectively, using this method. This method of forming the cutting elements allows for the bottom, and if appropriate, side surfaces, to have grooves of weaker material to facilitate breakage along fracture plane 48. This method of forming the cutting elements also allows for the bottom and side surfaces 40, 50, 60 to lack sharp edges which can be broken or cause damage during installation on the cutting tool, yet still provide a weak point to facilitate breakage along fracture plane 48.
Referring now to
It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. For example, fracture planes may also be included on the front and back surfaces of the cutting elements. Additionally, side grooves 54, 64 are not required to intersect valleys 29 of cutting profile 22. Instead, grooves 54, 64 can stop prior to reaching valleys 29 of cutting profiles 22. Similarly, grooves 54, 64 are not required to intersect grooves 44. Further, the grooves 54, 64 are not required to be perpendicular with groove 44. Nor do grooves 54, 64 need to be parallel to each other.
Moreover, grooves 44, and if present grooves 54, 64 can have any shape desired or necessary to encourage breakage along fracture plane 48. In addition, the fracture planes do not have to be “flat” as shown in the Figures, but instead can be undulating or curved, and it is to be understood that upon breakage along the fracture plane the surface of the segments are not smooth, but will include burrs and the like.
Further, the cutting elements may be used on any type of cutting tool including but not limited to mill blades, drill bits, and non-blade mills and may be included directly on the face of the cutting end of the tool. In addition, the angles of the fracture planes, cutting profile 22, and profile 32, can be modified as desired or necessary to facilitate placement of the cutting elements on the face or other structure carrying the cutting elements on the cutting end of the cutting tool or to facilitate cutting the object. Likewise, the shapes of the cutting elements can be modified as desired or necessary to facilitate placement of the cutting elements on the face or other structure carrying the cutting elements on the cutting end of the cutting tool. And, the lengths, widths, and heights of the horizontal and vertical side surfaces can also be modified as desired or necessary to facilitate placement of the cutting elements on the face or other structure carrying the cutting elements on the cutting end of the cutting tool or to facilitate cutting the object. In addition, the height does not need to be consistent or constant across either the length or width of the top surface or the length or width of the bottom surface.
Further, the cutting profile can be modified as desired or necessary to facilitate cutting the object. Moreover, the size and shape of the cutting surface portions on the top surface of the cutting elements can be modified as desired or necessary to facilitate placement of the cutting elements on the face or other structure carrying the cutting elements on the cutting end of the cutting tool or to facilitate cutting the object in the wellbore. Therefore, it is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.
