Downhole Cutting Arrangement and Method

Abstract

Devices and methods for cleaning or removing cuttings from a cut as cutting is being performed. A pipe cutter includes a housing shaped and sized to be disposed within the tubular member, a rotary cutting blade carried by the housing to cut the tubular member when rotated and an impeller operably associated with the cutting blade to create fluid flow and turbulence proximate a cut being made in the tubular member

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to cutting devices useful for cutting tubular members.

2. Description of the Related Art

Pipe cutters are used to cut tubular members. Pipe cutters typically include a circular cutting blade that is mounted upon a spindle. The spindle, in turn, is mounted upon an arm that can be moved radially out through a slot in a surrounding housing to be brought into cutting contact with a surrounding tubular member to be cut. During cutting, the blade can rotate at approximately 100 rpm. Pipe cutters are often used downhole, being run in on a tool string to cut a casing member within a wellbore. Commercially available pipe cutters include the MPC Mechanical Pipe Cutter from Baker Hughes Incorporated of Houston, Tex.

In operation, the pipe cutter is disposed within a tubular member to be cut, and the cutting blade is rotated by a motor. The arm is them moved so that the cutting blade is placed in cutting contact with the tubular member. The pipe cutter also rotates about it central axis, causing a circumferential cut to be made in the surrounding tubular member.

Cuttings or filings create a problem during cutting. They can cause damage to the cutting blade or prevent a clean cut from being made. As a cut is made deeper, the cuttings can become trapped within the cut, magnifying the problems.

SUMMARY OF THE INVENTION

The invention provides systems and methods for cleaning or removing cuttings from a cut as cutting is being performed. In a described embodiment, a downhole pipe cutter includes an impeller that is mounted proximate the cutting blade and rotates with the cutting blade. In a described embodiment, the impeller includes one or more paddles that extend radially outwardly from the hub of the spindle. In a particular embodiment, the one or more paddles extend radially outwardly from a central impeller ring. The impeller is rotated with the cutting blade. During cutting, the impeller paddles induce liquid flow and turbulence proximate the area of the tubular being cut. This flow and turbulence will wash and remove cuttings from the cut being made.

In particular embodiments, the impeller is formed of an elastomer. In alternative embodiments, the impeller is formed of polysiloxane, poly-ether-ether-ketone, polytetrafluoroethylene or another plastic or thermoplastic. In still other embodiments, the impeller is formed of steel or aluminum or another metal.

In an alternative embodiment, a flow housing is located partially around the impeller. In a described embodiment, the flow housing includes a top plate that lies substantially parallel to the cutting blade and a circumferential side wall that lies radially outside of the paddles. The flow housing helps to improve fluid flow proximate the cut being made.

BRIEF DESCRIPTION OF THE DRAWINGS

For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings, wherein like reference numerals designate like or similar elements throughout the several figures of the drawings and wherein:

FIG. 1 is an isometric view of an exemplary pipe cutter which incorporates an impeller in accordance with the present invention.

FIG. 2 is an enlarged isometric view of portions of the pipe cutter shown in FIG. 1.

FIG. 3 is an external, isometric view of an exemplary impeller shown apart from the other components of the pipe cutter.

FIG. 4 is a cross-sectional view showing the pipe cutter cutting an exemplary tubular member.

FIG. 5 is a cross-sectional view of an alternative embodiment pipe cutter which includes a flow housing proximate the impeller.

FIG. 6 is an isometric view of the alternative exemplary pipe cutter shown in FIG. 5.

FIG. 7 is a schematic side view of an alternative embodiment wherein an impeller is disposed on both axial sides of a cutting blade.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-4 depict an exemplary pipe cutter 10 which is used to cut tubular members. The pipe cutter 10 generally includes a tubular housing 12 having a tapered nose portion 14. The housing 12 is shaped and sized to be disposed within a tubular member that is to be cut. As can be seen with reference to FIG. 4, a cavity 16 is defined within the housing 12. The cavity 16 is shaped and sized to retain within a support arm 18 which carries a rotary spindle 20 as well as a circular cutting blade 22. A circular cutting blade 22 is mounted upon the spindle 20 and can be rotated by a motor (not shown) contained within the pipe cutter 10 in a manner known in the art. The support arm 18 is articulable so that the cutting blade 22 can be moved into or out of the cavity 16 during a cutting operation.

An impeller 24 is also mounted upon the spindle 20 and is rotated along with the cutting blade 22. The impeller 24 is preferably affixed to the cutting blade 22 using an adhesive or connectors or in another manner known in the art. In a particular embodiment, the impeller 24 includes one or more paddles 26 that extend radially outwardly along the lo blade from the vicinity of the spindle 20. In certain embodiments, the impeller 24 includes a central impeller ring 28 from which the paddles 26 extend radially outwardly. In the illustrated embodiment, there are eight paddles 26. However, there may be more or fewer than eight paddles 26.

In a particular embodiment, the impeller 24 is formed of an elastomer. In alternative embodiments, the impeller 24 is formed of polysiloxane, poly-ether-ether-ketone, polytetrafluoroethylene or another plastic or thermoplastic. In still other embodiments, the impeller 24 is formed of steel or aluminum or another metal. The impeller 24 can be formed by molding, water jet cutting, laser cutting, machining or in other ways known in the art. In the depicted embodiment, the impeller 24 is located on the lower side of the cutting blade 22 (i.e., the side that is further downhole), as illustrated in FIG. 1. However, it should be understood that the pipe cutter 10 would operate as effectively if the impeller 24 were placed on the upper side of the cutting blade 22. In addition, the cutting blade 22 might have an impeller 24 on both sides of the cutting blade 22. FIG. 7 depicts a cutting assembly wherein there are impellers 24 and 24 placed on both axial sides of a cutting blade 22.

During operation, the pipe cutter 10 is submerged within wellbore fluid. Typical wellbore fluids include brine, fresh water, seawater, production hydrocarbons and water or oil-based muds. FIG. 4 illustrates the pipe cutter 10 being used to cut a surrounding tubular member 30. As depicted, a cut 32 is being created as the cutting blade 22 is rotated in the direction of arrow 34. As cutting occurs, the paddies 26 push the fluid to create flow and turbulence in the wellbore fluid proximate the cut 32 in the general area shown at 36 in FIG. 4. This flow and turbulence will act to remove cuttings from the cut 32 and the area proximate the cut 32.

FIGS. 5 and 6 illustrate an alternative pipe cutter 10′ which includes a flow housing or shroud 40 which is located proximate the impeller 24. The flow housing 40 functions to help increase fluid flow proximate the cut 32. By containing fluid proximate the paddles 26, a more directed stream of higher velocity is created. In the depicted embodiment, the flow housing 40 includes a curved, crescent-shaped top plate 42 and a circumferential side wall 44 which are interconnected and form an interior enclosure 46. In the depicted embodiment, the flow housing 40 is supported by a support arm 48 which retains the flow housing 40 in a fixed position proximate the cutting blade 22 and impeller 24. The support arm 48 fixes the flow housing 40 in a position such that the top plate 42 is substantially parallel to the cutting blade 22 and the side wall 44 lies radially outside of the paddles 26.

A suitable grease can be used to assist cutting of high strength alloys or other materials. In a particular embodiment, the grease is applied to the paddles 26 prior to run-in and cutting. During operation to cut a tubular member, centrifugal force will cause grease to be applied to the cut from the paddles 26.

It can be seen that the invention also provides methods for cutting a tubular member. According to an exemplary method of cutting, the pipe cutter 10 or 10′ is disposed within a tubular member 30 to be cut. The cutting blade 22 is then rotated to cut the tubular member 30. The impeller 24 is rotated to cause fluid flow and turbulence proximate the cut being made in the tubular member, thereby helping to remove cuttings from the cut.

Those of skill in the art will recognize that numerous modifications and changes may be made to the exemplary designs and embodiments described herein and that the invention is limited only by the claims that follow and any equivalents thereof.

Claims

1. A pipe cutter for use in cutting a tubular member and comprising:

a housing shaped and sized to be disposed within the tubular member;

a rotary cutting blade carried by the housing to cut the tubular member when rotated; and

an impeller operably associated with the cutting blade to create fluid flow and turbulence proximate a cut being made in the tubular member.

2. The pipe cutter of claim 1 wherein the impeller comprises one or more paddles which extend radially along the blade.

3. The pipe cutter of claim 2 wherein the impeller further comprises an impeller ring from which the one or more paddles extend radially outwardly along the blade.

4. The pipe cutter of claim 1 wherein the impeller is affixed to the cutting blade.

5. The pipe cutter of claim 1 further comprising a flow housing operably associated with the impeller to direct fluid flow.

6. The pipe cutter of claim 5 wherein the flow housing comprises:

a top plate that lies substantially parallel to the cutting blade; and

a circumferential side wall that lies radially outside of the one or more paddles.

7. The pipe cutter of claim 1 wherein an impeller is disposed upon each axial side of the cutting blade.

8. A pipe cutter for use in cutting a tubular member and comprising:

a housing shaped and sized to be disposed within the tubular member;

a rotary cutting blade carried by the housing and mounted upon a spindle to cut the tubular member when rotated; and

an impeller operably associated with the cutting blade to create fluid flow and turbulence proximate a cut being made in the tubular member, the impeller comprising one or more paddles which extend radially along the cutting blade.

9. The pipe cutter of claim 8 wherein the impeller further comprises an impeller ring from which the one or more paddles extend radially outwardly along the blade.

10. The pipe cutter of claim 8 wherein the impeller is affixed to the cutting blade.

11. The pipe cutter of claim 8 further comprising a flow housing operably associated with the impeller to direct fluid flow.

12. The pipe cutter of claim 10 wherein the flow housing comprises:

a top plate that lies substantially parallel to the cutting blade; and

a circumferential side wall that lies radially outside of the one or more paddles.

13. The pipe cutter of claim 8 wherein an impeller is disposed upon each axial side of the cutting blade.

14. A method of cutting a tubular member comprising the steps of:

disposing a pipe cutter within the tubular member, the pipe cutter having a housing, a rotary cutting blade carried by the housing, and an impeller operably associated with the cutting blade and having one or more paddles which extend radially along the cutting blade;

rotating the cutting blade to cut the tubular member; and

rotating the impeller to create fluid flow and turbulence proximate the cut to help remove cuttings from the cut.

15. The method of claim 14 wherein the step of rotating the impeller to create fluid flow and turbulence further comprises pushing the fluid with one or more paddles.