Well Bore Casing Cutting Tool With Expandable Cutter Bases and Having Nose Section Cutting Capability
A wellbore casing cutting tool having multiple expandable cutter bases. The leading or downhole ends of the cutter bases are tapered, forming a tapered nose profile, and are covered with hardened cutting material to form a cutting surface. The cutting surface on the tapered nose profile can be used to remove a cement sheath within a casing string being cut or milled.
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Various tools have been developed for downhole cutting or severing of casing strings in wellbores, and for cutting or milling window sections in casing strings. Generally, such tools have comprised a main body with multiple hinged arms or blades, which are rotated outwardly into contact with the casing (by hydraulic or other means) when the tool is in position downhole. Usually, fluid is pumped down through the drillstring and through the tool to actuate the mechanism and rotate the blades outward. Once the blades are rotated outwardly, rotation of the drillstring (and tool) causes the cutting surfaces on the blades to cut through the casing string. Fluids are pumped through the system to lift the cuttings to the surface. Known tools, however, cannot efficiently cut or sever multiple, cemented-together casing strings, and in particular cannot efficiently cut “windows” in such strings; by the term “window” is meant the cutting or milling of a section (e.g. 20′) of the casing string, as opposed to simply severing same. In addition, known tools tend to form long, connected metal shavings which must be lifted from the wellbore by the fluid flow, else same become nested together downhole and potentially cause the drillstring to become stuck.
SUMMARY OF THE INVENTIONThe well bore casing cutting tool with expandable cutter bases and nose section cutting capability, embodying the principles of the present invention, comprises a main body having a longitudinal bore therethrough. Means for connecting the main body to a drill string, typically threaded connections, are provided on at least the upper end of the main body. A plurality of elongated cutter bases are hingedly connected to the main body by a plurality of linkage arms, and are movable from a first position substantially recessed into the main body, to a second position extended outwardly from the main body. An operating mechanism within the main body, operable by fluid flow, moves the linkage arms and cutter bases. The linkage arms hold the cutter bases substantially parallel to the axis of the main body. A plurality of cutters are mounted on the cutter bases, and engage the casing string when the cutter bases are in an outwardly extended position.
The cutter bases have a tapered nose section, preferably covered with a hardened cutting surface such as tungsten carbide. This permits cutting by the nose section of the tool. In addition, the operating mechanism is modified to permit enhanced fluid flow to selected areas of the tool, when it is in different operating positions.
Preferably, the operating piston of the tool is maintained in alignment in the main body of the tool by a pair of alignment pins, rather than alignment blocks of earlier designs.
While a number of embodiments are possible, within the scope of the invention, with reference to the drawings some of the presently preferred embodiments can be described.
As shown in
As can be seen in the figures, especially
Cutting tool 10 comprises a means for moving cutter bases 30 from a first, retracted position, generally within main body 20 and not protruding significantly therefrom, as shown in
An alternative embodiment of the operating mechanism, shown in
Referring to the drawings, cutter bases 30 comprise a plurality of cutters 40 mounted thereon (for space and clarity, not all of cutters 40 are so annotated). While various embodiments of cutters may be used, one suitable embodiment uses a metal base or cutter plate which is attached to cutter base 30 by welding or similar means; on the cutter plate is attached a plurality of metal cutting surfaces, such as carbide buttons or inserts, or hardened buttons of other materials, or other means known in the art; alternatively the cutter plates may be covered with carbide or other suitable hardened surface, or a combination of hardened material buttons and carbide or similar materials. A variety of cutting surfaces are suitable, as long as they present a hardened surface to the upward-facing casing edge to permit milling of same. Further detail regarding acceptable cutting surfaces is set forth below.
As can be seen in
Generally, cutter bases 30 are sized so as to fit generally within the radius of main body 30 when retracted, as in
With fluid circulation ongoing, thereby extending cutter bases 30 and cutters 40 to the position shown in
Yet another attribute of cutting tool 10 is the centering and stabilizing aspect of cutter bases 30 in conjunction with the positioning arms 50. Preferably, a section of cutter bases 30 has no cutters 40 mounted thereon, as noted in certain of the figures as stabilizing section 32. As is readily understood with reference to
Another preferred attribute of cutting tool 10 is that the dimensions of positioning arms 50 and cutter bases 30 are such as to enable cutter bases 30 to bear against and be supported by main body 20, when cutter bases 30 are in their second, extended position; this is shown at the location noted as 31 in
Those skilled in the art will recognize that tapered nose section 34 yields significant added utility to cutting tool 10, as the tool is capable of cutting and/or milling through obstacles disposed below it in a wellbore. The particular shape and configuration of the nose section taper can be modified to suit particular needs. The type, location, and placement of hardened cutting surface 34A can likewise be modified to suit particular applications.
Partial Opening of Tool to Clear Cement SheathIn a presently preferred embodiment, the heel portions 50A of positioning arms 50 are modified so as to direct fluid flow in a desired direction, depending upon the operating position of cutting tool 10. In
Piston 21 is disposed in bore 26, so as to move longitudinally in the bore in response to fluid flow. While piston 21 is aligned in bore 26 to an extent by its shape, and by seal assembly 21B (which provides a fluid seal around piston 21 in bore 26), additional alignment is desired for the smaller diameter section 21D of piston 21. Earlier known designs utilized alignment blocks positioned within bore 26. The presently preferred embodiment of the present invention uses a pair of pins 21C (only one pin shown for clarity), inserted through holes 21E in main body 20. Pins 21C are positioned so as to closely constrain piston 21, and more specifically smaller diameter section 21D, from side to side movement. Pins 21C are more easily fitted, removed and replaced than are alignment blocks.
Method of Use of the Cutting ToolAn exemplary method of use of cutting tool 10 with expandable cutter bases 30 can now be described. A main body 20, cutter bases 30, and positioning arms 50, with multiple cutters attached to each cutter base 30, are selected with dimensions appropriate for the size casing that is to be cut. A relatively short downhole window is first cut in the tubular in interest, with a two-arm casing cutter or conventional cutting tool, or with cutting tool 10 when configured for that task. As seen in
The next step is to locate cutting tool 10 within window 72. Although various methods are possible, one preferred method is to lower cutting tool 10 to a depth known to be slightly below window 72. Fluid circulation is then started, which will move cutter bases 30 (and cutters 40) outward, into contact with the casing wall. Cutting tool 10 is then pulled uphole, while cutters 40 are in contact with the casing wall. When cutting tool 10 is positioned within casing window 72 such that the lowermost cutters are above the casing edge, cutter bases 30 can fully extend and multiple indicators will be noted at the surface, including a decrease in drag, change in pump pressure, decrease in torque, etc. Now, the stabilizing section 32 of cutter bases 30 will be positioned against the wall of the casing, and cutters 40 will be positioned over the casing edge; this is the position seen in
While the preceding description contains many specificities, it is to be understood that same are presented only to describe some of the presently preferred embodiments of the invention, and not by way of limitation. Changes can be made to various aspects of the invention, without departing from the scope thereof. For example, dimensions of the various components of the tool can be varied to suit particular jobs; the number of cutter bases can be varied; the number and positioning of cutters per cutter base can be varied; size and shape of the cutters can vary; and methods of use can ye varied.
Therefore, the scope of the invention is to be determined not by the illustrative examples set forth above, but by the appended claims and their legal equivalents.
Claims
1. An apparatus for cutting wellbore casing downhole, comprising:
- a main body comprising a longitudinal bore and a plurality of elongated cutter bases movably attached thereto, said cutter bases attached to said main body by a plurality of positioning arms hingedly connected thereto, said positioning arms being of substantially equal length so that said cutter bases remain substantially parallel to a longitudinal axis of said main body when moved between a first retracted position and a second extended position;
- a plurality of cutters attached to an upper section of each of said cutter bases, whereby a lower section of said cutter bases without cutters comprises a stabilizer section;
- an operating mechanism for moving said cutter bases from said first retracted position to said second extended position, said operating mechanism comprising a sliding piston disposed in said bore of said main body and movable by fluid flow through said bore of said main body, said piston having an upper section with a diameter closely fitting a diameter of said main body bore and a seal element between said upper section of said piston and said bore, and a lower section with a reduced diameter, said piston positioned so as to engage a heel section of said positioning arms and bear down on same so as to rotate said positioning arms outwardly and move said elongated cutter bases from said first position to said second position, said piston further having a longitudinal bore therethrough;
- each of said cutter bases having a tapered nose section on a lower end, said tapered nose section comprising a hardened cutting surface thereon.
2. The apparatus of claim 1, wherein said positioning arms comprise heel sections shaped wherein a fluid path downhole through said main body bore is created when said positioning arms are in an extended position, and wherein said said piston comprises a plurality of angled flow passages such that a portion of fluid flow through said piston bore flows through said fluid path in said positioning arms heel portions, and a portion of fluid flow is angled outwardly onto said positioning arms.
3. The apparatus of claim 1, further comprising a pair of pins disposed in said main body proximal said lower section of said piston within said main body bore, so as to align said lower piston section within said main body bore.
4. The apparatus of claim 3, wherein said cutters are elongated along said cutter bases and positioned such that an upper end of said cutters is inclined in a direction of rotation of said apparatus.
5. The apparatus of claim 4, wherein said cutters comprise carbide covered cutting surfaces.
6. The apparatus of claim 4, wherein said cutters comprise carbide buttons.
7. The apparatus of claim 4, wherein said cutters comprise polycrystalline diamond compact inserts.
8. The apparatus of claim 1, further comprising a jetted sub and a safety joint positioned above said main body.
9. The apparatus of claim 1, wherein said positioning arms and cutter bases are dimensioned so that said positioning arms and said cutter bases, when said cutter bases are in said second extended position, bear against said main body.
10. An apparatus for cutting wellbore casing downhole, comprising:
- a main body comprising a longitudinal bore and a plurality of elongated cutter bases movably attached thereto, said cutter bases attached to said main body by a plurality of positioning arms hingedly connected thereto, said positioning arms being of substantially equal length so that said cutter bases remain substantially parallel to a longitudinal axis of said main body when moved between a first retracted position and a second extended position;
- a plurality of cutters attached to an upper section of each of said cutter bases, whereby a lower section of said cutter bases without cutters comprises a stabilizer section;
- a means for moving said cutter bases from said first retracted position to said second extended position, said means comprising a sliding piston disposed in said bore of said main body and movable by fluid flow through said bore of said main body, said piston having an upper section with a diameter closely fitting a diameter of said main body bore and a seal element between said upper section of said piston and said bore, and a lower section with a reduced diameter, said piston positioned so as to engage a heel section of said positioning arms and bear down on same so as to rotate said positioning arms outwardly and move said elongated cutter bases from said first position to said second position, said piston further having a longitudinal bore therethrough;
- further comprising a pair of pins disposed in said main body proximal said lower section of said piston within said main body bore, so as to align said lower piston section within said main body bore.
11. The apparatus of claim 10, wherein each of said cutter bases comprises a tapered nose section on a lower end, said tapered nose section comprising a hardened cutting surface thereon.
12. An apparatus for cutting wellbore casing downhole, comprising:
- a main body comprising a longitudinal bore and a plurality of elongated cutter bases movably attached thereto, said cutter bases attached to said main body by a plurality of positioning arms hingedly connected thereto, said positioning arms comprising gear teeth thereon, said positioning arms being of substantially equal length so that said cutter bases remain substantially parallel to a longitudinal axis of said main body when moved between a first retracted position and a second extended position;
- a plurality of cutters attached to an upper section of each of said cutter bases, whereby a lower section of said cutter bases without cutters comprises a stabilizer section;
- an operating mechanism for moving said cutter bases from said first retracted position to said second extended position, said operating mechanism comprising a sliding piston disposed in said bore of said main body and movable by fluid flow through said bore of said main body, said piston having an upper section with a diameter closely fitting a diameter of said main body bore and a seal element between said upper section of said piston and said bore, and a lower section with a reduced diameter, said lower section comprising gear teeth thereon, whereby said piston gear teeth engage said positioning arm gear teeth and with longitudinal movement of said piston rotate said positioning arms outwardly and move said elongated cutter bases from said first position to said second position, said piston further having a longitudinal bore therethrough;
- each of said cutter bases having a tapered nose section on a lower end, said tapered nose section comprising a hardened cutting surface thereon.
13. A method of milling a casing string having a cement sheath on an interior wall thereof, comprising the steps of:
- a. milling a window in a desired downhole location in said casing string, leaving an upwardly facing casing edge;
- b. providing an apparatus comprising: a main body comprising a longitudinal bore and a plurality of elongated cutter bases movably attached thereto, said cutter bases attached to said main body by a plurality of positioning arms hingedly connected thereto, said positioning arms being of substantially equal length so that said cutter bases remain substantially parallel to a longitudinal axis of said main body when moved between a first retracted position and a second extended position; a plurality of cutters attached to an upper section of each of said cutter bases, whereby a lower section of said cutter bases without cutters comprises a stabilizer section; a means for moving said cutter bases from said first retracted position to said second extended position, said means comprising a sliding piston disposed in said bore of said main body and movable by fluid flow through said bore of said main body, said piston having an upper section with a diameter closely fitting a diameter of said main body bore and a seal element between said upper section of said piston and said bore, and a lower section with a reduced diameter, said piston positioned so as to engage a heel section of said positioning arms and bear down on same so as to rotate said positioning arms outwardly and move said elongated cutter bases from said first position to said second position, said piston further having a longitudinal bore therethrough; each of said cutter bases having a tapered nose section on a lower end, said tapered nose section comprising a hardened cutting surface thereon;
- c. lowering said apparatus downhole on a drillstring and positioning said apparatus so that said cutters are within said window, with said stabilizer section of said cutter bases below said window;
- d. pumping fluid down said drillstring so as to move said cutter bases outward so that said stabilizer section of said cutter bases contact said inner wall of said casing;
- e. rotating and lowering said apparatus so as to contact said cement sheath with said cutting surfaces on said tapered nose of said cutter bases and remove said cement sheath, and continuing to rotate and lower said apparatus until said cutters contact said upwardly facing casing edge;
- f. rotating and lowering said apparatus, while pumping fluid flow through said apparatus, while cutting said casing with said cutters and removing any cement sheath on said inner casing wall with said tapered nose cutting surface.
Type: Application
Filed: May 1, 2015
Publication Date: Aug 24, 2017
Applicant: Abrado, Inc. (Houston, TX)
Inventor: David J. Ruttley (Marrero, LA)
Application Number: 15/310,157