Cutting elements for downhole cutting tools

Cutting elements for downhole cutting tools comprise a top surface having a cutting surface portion and a cutting profile asymmetrically disposed across the top surface. The cutting elements comprise first and second longitudinal side surfaces and first and second lateral side surfaces, each having a respective cross-section. The cross-section of one of the longitudinal side surfaces can have one beveled portion and the cross-sections of the other longitudinal side surface and the first and second lateral side surfaces can have two beveled portions. A cutting end of a downhole cutting tool comprises two cutting elements disposed facing each another with a portion of the cutting surface portion of a first cutting element being disposed opposite the cutting profile of the second cutting element and the cutting surface portion of the second cutting element being disposed opposite the cutting profile of the first cutting element.

BACKGROUND

1. Field of Invention

The invention is directed to cutting elements or “cutters” for downhole cutting tools utilized in oil and gas wells to cut objects within the well and, in particular, to cutting elements that comprise a cutting profile disposed asymmetrically across a top surface of the cutting element to facilitate placement of the cutting elements on the cutting end of the downhole cutting tools for cutting away, among other objects, stuck tools, bridge plugs, well tubing, well casing, and the like disposed within the well.

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; however, the shape, size, and design of the cutting elements can limit the locations in which the cutting elements can be placed. For example, the shape, size, and design of the cutting elements limit the ability of the tool to provide effective cutting of the object disposed below the center point of the tool.

SUMMARY OF INVENTION

Broadly, the invention is directed to cutting elements disposed on downhole cutting tools utilized in cutting away objects disposed within the well. The term “object” encompasses any physical structure that may be 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 tools 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. One or more of the blades include a front side surface that has disposed on it one or more cutting elements, a back side surface, an outer end, an inner end, and at least one beveled portion disposed on the front side surface toward the inner end. The back side surface generally does not include any cutting elements. The presence of the cutting element on the beveled portion allows the blade to be position such that the center point of the face of the downhole cutting tool is covered by a cutting element. In this arrangement, rotation of the downhole cutting tool provides for the portion of the object disposed directly below the center point of the face of the downhole cutting tool to be cut away.

In one specific embodiment, the cutting elements comprise a top surface having an asymmetrically disposed cutting profile. The placement of the cutting profile asymmetrically on the top surface provides areas on the top surface that are not raised. In one particular embodiment, the placement of the cutting profile asymmetrically provides at least one cutting surface portion or area that is larger than any other cutting surface portions or areas, if any others are present.

In other specific embodiments, the cutting elements comprise various shapes and designs to facilitate placement of the cutting elements on the face or other structure carrying the cutting elements on the cutting end of the downhole cutting tool and to facilitate cutting the object in the wellbore.

DETAILED DESCRIPTION OF INVENTION

Referring now toFIG. 1, downhole cutting tool10comprises blade mill20having body or housing22adapted at upper end23to be connected to drill or work string15, cutting end24having face25, drilling fluid ports26through which drilling or cutting fluid flows to facilitate cutting by blade mill20, and, as shown in the specific embodiment in the Figures, six blades40. Affixed to a front or forward face of each of the six blades40are one or more cutting elements50. In addition, as shown inFIG. 1, two cutting elements50are disposed on beveled portions42of blades40facing toward each other across center point30of face25so that the portion of the object below center point30can be cut by cutting elements50. And, as further shown inFIG. 1, these two cutting elements50disposed on beveled portions42overlap one another to facilitate cutting the portion of the object below the center point This overlapping increases the strength and durability of these two cutting elements50and decreases the probability that any uncut portion of the object remains that could be forced between the two cutting elements50causing the two cutting elements50to wedge apart and possibly break. It is to be understood that although the cutting elements50are shown inFIG. 1as having various shapes, sizes, and designs, any one of the cutting elements50may have one or more of the features discussed below.

Referring now toFIGS. 2-12, cutting element50comprises top surface or cutting face54, first longitudinal side surface56, second longitudinal side surface58, first lateral side surface60, second lateral side surface62, and bottom surface64(FIG. 3). Cutting element50includes a central longitudinal axis150(FIG. 2). First and second lateral side surfaces60,62define top surface length66(shown inFIG. 2), i.e., the length of cutting element50along top surface54between first and second lateral side surfaces60,62. Length66can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, length66can be in the range from 0.25 inches to 1 inch. In one specific embodiment, length66is 0.625 inches.

First and second lateral side surfaces60,62also define bottom surface length74(shown inFIG. 4), i.e., the length of cutting element50along bottom surface64between first and second lateral side surfaces60,62. Length74can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, length74can be in the range from 0.25 inches to 1 inch. In one specific embodiment, length74is 0.473 inches.

First and second longitudinal side surfaces56,58define top surface width68(shown inFIG. 2), i.e., the width of cutting element50along top surface54between first and second longitudinal side surfaces56,58. Width68can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, width68can be can be in the range from 0.25 inches to 1 inch. In one specific embodiment, width68is 0.375 inches.

First and second longitudinal side surfaces56,58define bottom surface width72(shown inFIG. 3), i.e., the width of cutting element50along bottom surface64between first and second longitudinal side surfaces56,58. Width72can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, width72can be can be in the range from 0.25 inches to 1 inch. In one specific embodiment, width72is 0.281 inches.

Top surface54and bottom surface64define height70(shown inFIG. 3). Height70can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, height70can be can be in the range from 0.1 inches to 1 inch. In one specific embodiment, height70is 0.250 inches.

As shown in the embodiment of the Figures, cutting element50comprises first radial surface57disposed between first longitudinal side surface56and first lateral side surface60, second radial surface59disposed between first lateral side surface60and second longitudinal side surface58, third radial surface61disposed between second longitudinal side surface58and second lateral side surface62, and fourth radial surface63disposed between second lateral side surface62and first longitudinal side surface56. Each of radial surfaces57,59,61,63comprise a radius of curvature. Each of the radii of curvature of radial surfaces57,59,61,63can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, the radii of curvature of radial surfaces57,59,61,63can be in the range from 0.010 inches to 1 inch. In the particular embodiment ofFIGS. 2-8, the radius of curvature of radial surface57is equal to the radius of curvature of radial surface63, the radius of curvature of radial surface59is equal to the radius of curvature of radial surface61, and the radii of curvature of radial surfaces57,63are not equal to the radii of curvature of radial surfaces59,61. In one specific embodiment, the radius of curvature of radial surface57is 0.188 inches, radius of curvature of radial surface59is 0.090 inches, radius of curvature of radial surface61is 0.090 inches, and radius of curvature of radial surface63is 0.188 inches.

As best illustrated inFIGS. 3-4, cutting profile76comprises recess86and cutting edge88which define depth87(shown inFIG. 4) of cutting profile76. Depth87can be any distance/measurement desired or necessary to facilitate cutting an object (not shown) disposed in a wellbore. For example, depth87can be can be in the range from 0.010 inches to 1 inch. In one specific embodiment, depth87is 0.040 inches.

Cutting edge88is shown as having an oval shape, however, it is to be understood that cutting edge88can have any shape desired or necessary to facilitate cutting an object (not shown) disposed in a wellbore, e.g., rectangular, square, circular, egg-shaped, and the like. As shown in the Figures, cutting edge88is defined by two angles89,90. Angles89,90can be set at any degree desired or necessary to facilitate cutting the object. For example, angles89,90can be in the range from 15 degrees to 75 degrees. In one specific embodiment, angles89,90are 45 degrees.

Cutting profile76is asymmetrically disposed on top surface or cutting face54of cutting element50. As used herein, the term “asymmetrically” means cutting profile76is not centered on top surface54. Thus, one or more portions or areas of top surface54disposed around the outside or circumference of cutting profile76is not equal to any other such portions. These portions are referred to herein as “cutting surface portions” of top surface or cutting face54. The cutting surface portion(s) facilitate the overlapping of two cutting elements50such as shown inFIG. 1(discussed above) andFIGS. 9-12(discussed in greater detail below).

As shown inFIGS. 2-8, this embodiment of cutting element50comprises numerous cutting surface portions, four of which are defined by the longitudinal and lateral edges of cutting edge88and first and second longitudinal side surfaces56,58and first and second lateral side surfaces60,62. Cutting surface portion78is defined by first lateral side surface60and a first lateral edge of cutting edge88. Cutting surface portion80is defined by second lateral side surface62and a second lateral edge of cutting edge88. As used herein, “lateral edge” means the portion of cutting edge88that is closest to first lateral side surface60or second lateral side surface62.

Cutting surface portion82is defined by first longitudinal side surface56and a first longitudinal edge of cutting edge88. Cutting surface portion84is defined by second longitudinal side surface58and a second longitudinal edge of cutting edge88. As used herein, “longitudinal edge” means the portion of cutting edge88that is closest to first longitudinal side surface56or second longitudinal side surface58.

Each of cutting surface portions78,80,82,84comprise a distance/measurement. Distance79(FIG. 4) is defined as the measurement from cutting edge88to first lateral side surface60. Distance81(FIG. 4) is defined as the measurement from cutting edge88to second lateral side surface62. Distance83(FIG. 3) is defined as the measurement from cutting edge88to first longitudinal side surface56. Distance85(FIG. 3) is defined as the measurement from cutting edge88to second longitudinal side surface58. As shown in the drawings, distance79is greater than distances81,83, and85so that cutting surface portion78has a larger area compared to cutting surface portions80,82, and84. However, it is to be understood, that distances79,81,83, and85can be modified in any way desired or necessary to facilitate cutting the object in the wellbore. For example, distance79can be in the range from 0.080 inches to 0.120 inches, distance81can be in the range from 0.01 inches to 0.090 inches, distance83can be in the range from 0.01 inches to 0.090 inches, and distance85can be in the range from 0.01 inches to 0.090 inches. In one particular embodiment, distance79is at least twice as long as distance81. In another embodiment, distance79is 0.102 inches, distance81is 0.040 inches, distance83is 0.040 inches, and distance85is 0.040 inches.

As illustrated inFIG. 5, a cross-section view of second longitudinal side surface58shows that second longitudinal side surface58comprises bevel portion94disposed at angle95relative to axis98. Axis98is disposed perpendicular to top surface54. Angle95can be in the range from 3 degrees to 12 degrees. In a specific embodiment angle95is 5 degrees.

In addition, cross-section view of second longitudinal side surface58shows that second longitudinal side surface58includes upper portion92that is parallel to axis98and lower portion96that is parallel to axis98. Length93of upper portion92can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, length93can be in the range from 0.01 inches to 0.035 inches. In a specific embodiment, length93of upper portion92is 0.025 inches.

Length97of lower portion96can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, length97can be in the range from 0.001 inches to 0.010 inches. In a specific embodiment, length97of lower portion96is 0.005 inches.

As shown inFIGS. 6-7, first lateral side surface60comprises upper beveled portion100disposed at angle102relative to axis98, and lower beveled portion104disposed at angle106relative to axis98. In the embodiment shown in the Figures, upper beveled portion100is disposed adjacent to lower beveled portion104.

Length103of upper beveled portion100can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, length103can be can be in the range from 0.025 inches to 1 inch. In a particular embodiment, length103is 0.085 inches.

Angles102,106can be any angle desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, angle102can be in the range from 10 degrees to 20 degrees and angle106can be in the range from 20 degrees to 30 degrees. In a specific embodiment angle102is 15 degrees and angle106is 24 degrees.

In addition, cross-section view of first lateral side surface60shows that first lateral side surface60includes upper portion108that is parallel to axis98and lower portion110that is parallel to axis98. Length109of upper portion108can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, length109can be in the range from 0.01 inches to 0.035 inches. In a specific embodiment, length109of upper portion108is 0.025 inches.

Length111of lower portion110can be any distance/measurement desired or necessary to facilitate placement of cutting element50on cutting end24of a downhole cutting tool. For example, length111can be in the range from 0.001 inches to 0.010 inches. In a specific embodiment, length111of lower portion110is 0.005 inches.

Although not shown in detail, it is to be understood that in the embodiment shown inFIGS. 2-12, the cross-section of second lateral side surface62is the same as the cross-section of first lateral side surface60. In other words, the cross-section of second lateral side surface62has the same beveled portions, parallel portions, and angles as first lateral side surface60. It is also to be understood that these cross-sections are not required to be identical.

Further, it is to be understood that the cross-section of first longitudinal side surface56can include beveled portions, parallel portions, and angles. In the specific embodiment shown in the Figures, first longitudinal side surface56includes beveled portions, parallel portions, and angles that coincide with, and are identical to, beveled portions,100,104, parallel portions108,110, and angles102,106of first and second lateral side surfaces60,62. It is also to be understood that the cross-section of first longitudinal side surface56is not required to be identical to the cross-sections of either first or second lateral side surfaces60,62.

Referring with particular reference toFIGS. 9-10, but as also illustrated inFIG. 1, two cutting elements50,50′ are shown in relation to one another as they can be arranged on cutting end24of downhole cutting tool20, such as on two blades40as shown inFIG. 1or directly on a continuous face, such as face25of cutting end24. As illustrated, the top surfaces or cutting faces54of the two cutting elements50,50′ are disposed facing each other with cutting surface portion78of cutting element50being disposed opposite cutting profile76of cutting element50′, and cutting surface portion78of cutting element50′ being disposed opposite cutting profile76of cutting element50. As shown inFIGS. 9-10, cutting elements50,50′ are disposed parallel to each other with second longitudinal side surfaces58of cutting elements50,50′ aligned with each other, and first longitudinal side surfaces56of cutting elements50,50′ aligned with each other.

Referring now toFIGS. 11-12, cutting elements50,50′ are disposed at a non-parallel angle with respect to each other. In the arrangement ofFIG. 11, second longitudinal side surfaces58of cutting elements50,50′ define an acute angle. In this orientation cutting elements50,50′ can be disposed on the cutting end24such that rotation of the tool10allows cutting elements50,50′ to contact the object in the well toward the ends of cutting profiles76toward lateral ends60.

In the arrangement ofFIG. 12, first longitudinal side surfaces56of cutting elements50,50′ define an acute angle. In this orientation, cutting elements50,50′ can be disposed on the cutting end24such that rotation of the tool10allows cutting elements50,50′ to contact the object in the well toward the ends of cutting profiles76toward lateral ends62.

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, the cutting elements are shown inFIG. 1as being used on a mill blade, however, the cutting elements may be included on any type of downhole cutting tool such as drill bits and non-blade mills and may be included directly on the face of the cutting end of the tool. Moreover, the angles of the bevel portions of the longitudinal and lateral side surfaces 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 downhole cutting tool or to facilitate cutting the object in the wellbore. 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 downhole cutting tool. And, the lengths, widths, and heights of the longitudinal and lateral 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 downhole cutting tool or to facilitate cutting the object in the wellbore. 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. Nor are is there any requirement that the cutting elements include any radial surfaces, or that if two or more radial surfaces are present, that any one radius of curvature is equal to any other radius of curvature.

Further, the cutting profile can be modified as desired or necessary to facilitate cutting the object in the wellbore. 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 downhole cutting tool or to facilitate cutting the object in the wellbore. And, although the cutting elements are shown inFIG. 1as being disposed perpendicular to the blades, i.e., at an angle of 90 degrees relative to the blade, one or more of the cutting elements may be tilted downwardly or upwardly at an angle other than 90 degrees relative to the blades. 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.