REVERSE CIRCULATION JUNK BASKET

Abstract

An apparatus and method for capturing debris and metal cuttings downhole in a wellbore. Fluid is reverse circulated through a tubing positioned in the wellbore. An aperture opens to a larger space within the tubing interior and creates a pressure drop which separates the debris from the fluid. The debris is separated from the fluid and is collected by an interior space within the tubing. The tubing can be retrieved from the wellbore so that the debris is separated from the interior space.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to completion and repair operations downhole in wellbores. More particularly, the invention relates to an improved apparatus and method for capturing metal debris and metal cuttings downhole in the wellbore.

[0002] Metal debris known as “junk” and metal cuttings and other impurities are generated during wellbore completion and repair operations. To create a window in the side wall of wellbore casing, rotating mills are directed by a whipstock or similar device against the casing interior wall. The rotating mills generate metal cuttings heavier than the circulating fluid. Other types of rotating mills remove packers and broken equipment from a wellbore and clear obstructions from the wellbore. Metal cuttings from such operations restrict wellbore production and encumber tool movement through the wellbore.

[0003] “Junk baskets” operate with mills to capture debris and metal cuttings during wellbore completions and milling operations. Junk baskets are typically positioned on the drill stem exterior surface as shown in U.S. Pat. No. 3,814,180 to Oliver (1974), which disclosed a junk basket surrounding the tubular above a drilling bit. U.S. Pat. No. 3,907,047 to Thompson et al. (1975) disclosed a junk basket attached to a rotary drill bit which included an annular cup. U.S. Pat. No. 4,111,262 to Duncan (1978) disclosed a flexible junk boot clamped to the drill string exterior. U.S. Pat. No. 4,217,966 to Garrett (1980) disclosed a metal cup spindled on a drill bit pin so that the cup was automatically dumped each time that the drill bit was removed from the stem. Additionally, U.S. Pat. No. 4,390,064 to Enen et al. (1983) disclosed a releasable junk basket attachable to the drilling string exterior

[0004] Certain junk baskets operate movable sleeves to collect debris within a chamber. U.S. Pat. No. 5,135,050 to Tailby (1992) disclosed a piston-like sleeve for use in horizontal wells which was releasable to open ports for collecting a quantity of debris in a chamber. Other junk baskets use magnets to attract and capture metal fragments and cuttings. U.S. Pat. No. 4,059,155 to Greer (1977) disclosed a magnet assembly in a longitudinally extending passageway for capturing metal fragments. U.S. Pat. No. 5,944,100 to Hipp (1999) disclosed magnets attached to a tool body and flexible fingers or brushes to move the debris from the magnets toward a storage area.

[0005] Although most junk baskets are located exterior of the tubular, U.S. Pat. No. 4,276,931 to Murray (1979) disclosed a junk retaining means located within a tubular body. “Catchers” having pivoted fingers were located above the milling teeth for capturing metal debris. A reduced fluid pressure for drawing junk into a chamber was created by activating inwardly extending fluid jets. The jets were supported by a jet housing and were activated by a pressure responsive activating means to capture junk within the wellbore.

[0006] The proliferation of multilateral wells and complex wellbore completion systems increases the need for milling operations in wellbores. Increasingly close tolerances in valves and well control equipment requires tight control over debris in the wellbores. Additionally, conventional debris capture systems do not always provide for selective fluid pressure control within a selected wellbore location. Accordingly, a need exists for an improved method and apparatus for capturing metal cuttings and other debris downhole in a wellbore.

SUMMARY OF THE INVENTION

[0007] The present invention provides an apparatus and method for capturing debris downhole in a wellbore when fluid is reverse circulated through the wellbore. The apparatus comprises a hollow basket housing attached to said tubular, a basket member positioned within the basket housing to define an interior volume between the basket housing and the basket member for capturing the debris, and an aperture in the basket member for permitting reverse circulated flow of the fluid and debris therethrough, wherein the aperture has a dimension smaller than an interior dimension of the hollow tubular to generate a pressure drop proximate to the basket member to facilitate separation of the debris from the fluid.

[0008] In another embodiment of the invention, the apparatus comprises a hollow tubular operable from the wellbore surface, a cutter head, and a basket attached between the cutter head and the tubular, wherein the basket comprises an exterior housing and an interior member having an aperture for permitting flow of the fluid and debris therethrough, and wherein the interior member and the exterior housing form an interior volume for capturing the debris as the fluid and debris are reverse circulated through the aperture.

[0009] The method of the invention comprises the steps of attaching a basket housing to a tubular to define an interior volume within the tubular, wherein the basket housing includes an aperture for permitting fluid flow therethrough, of positioning the tubular and basket housing downhole in a wellbore, of reverse circulating fluid to move the debris through the aperture, and of separating the debris from the fluid as the debris and fluid passes through the aperture so that the debris is captured within the basket housing interior volume.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 illustrates an elevation view of an aperture in a basket housing having an interior volume for capturing debris.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The invention provides an apparatus and method for capturing debris downhole in a wellbore. The invention is particularly suited for capturing metal filings generated during milling operations.

[0012] FIG. 1 illustrates one embodiment of the invention wherein tubular 10 formed with one or more sections is positioned within wellbore 12. Basket 14 is attached to tubular 10 and generally comprises basket housing 16 and basket member 18. Basket housing 16 has threadforms 20 and 22 for integral connection to tubular 10. Basket housing 16 is formed with lower section 24 and upper section 26 connected with threadform 28. The interior wall of basket housing 16 is cylindrical with a diameter substantially similar to the interior diameter of tubular 10 in a preferred embodiment of the invention. However, the shape, configuration and dimensions of tubular 10 and of basket housing 16 can be shaped in different ways to accomplish different design criteria, however basket housing 16 is hollow to permit the passage of fluid and of debris therethrough..

[0013] An interior member or basket member 30 is attached to basket housing 16 for the purpose of constricting fluid flow through aperture 32 and for the purpose of forming interior volume 34. As shown in FIG. 1, collar 36 is retained between surfaces 38 and 40 on lower section 24 and on upper section 26 respectively. Collar 36 has aperture 32 therethrough and is attached with threadform 42 to sleeve 44. The exterior surface of sleeve 44 and the interior wall of upper section 26 define a toroidal shaped space identified as interior volume 34. Interior volume 34 has closed end 46 and open end 48. Although interior volume 34 is formed as a toroid, the configuration, shape, orientation and relative size of such component can be varied to accomplish different design objectives.

[0014] As shown in FIG. 1, mill 50 can be attached to threadform 22 to generate metal cuttings in wellbore 12. If tubular 10 is rotatable from the surface of wellbore 12, mill 50 will not require additional drive components.

[0015] Reverse circulation of fluid 52 in the direction shown will transport debris such as junk or metal cuttings upwardly through aperture 32. Sloped surface 54 can direct fluid 52 and the metal cuttings toward aperture 32. As fluid 52 and the transported metal cuttings travels through aperture 32 and exits through sleeve 44 into the interior of upper section 26, the pressure of fluid 52 is reduced and the flow rate is correspondingly decreased. At such location the transported metal cuttings separate from fluid 52 and fall by gravity into interior volume 34. Fluid 52 moves upwardly from the captured metal cuttings as fluid 52 is circulated through tubular 10.

[0016] The invention is particularly suitable for the purposes of washing pipe and tubing connections, and can be run to mill over junk or through packers to prevent mill cuttings from falling downwardly and being re-milled. By effectively capturing the metal cuttings, the useful life of a mill shoe such as mill 50 will be extended, therefore reducing the number of trips necessary to replace mill 50.

[0017] The invention is also useful if the wellbore 12 is losing fluid downhole because fluid 52 can be reverse circulated with low pressure. As the metal cuttings tend to fall downwardly through gravity, the metal cuttings are captured within interior volume 34 and do not reach mill 50.

[0018] The invention can be used with a hydro-static baller or mud pump for light milling operations or to retrieve small pieces of debris or junk that would otherwise flow through a drain sub or flapper valve. The invention can be used to mill up loose debris and bridge plugs and can be run with a drill bit or mill. The invention is particularly suitable with a whipstock in milling operations which form a window in exterior casing pipe set in wellbore 12.

[0019] Although the invention has been described in terms of certain preferred embodiments, it will become apparent to those of ordinary skill in the art that modifications and improvements can be made to the inventive concepts herein without departing from the scope of the invention. The embodiments shown herein are merely illustrative of the inventive concepts and should not be interpreted as limiting the scope of the invention.

Claims

1. An apparatus for capturing debris downhole in a wellbore when fluid is reverse circulated through the wellbore and through a hollow tubular positioned in the wellbore, comprising:

a hollow basket housing attached to said tubular;

a basket member positioned within said basket housing to define an interior volume between said basket housing and said basket member for capturing the debris; and

an aperture in said basket member for permitting reverse circulated flow of the fluid and debris therethrough, wherein said aperture has a dimension smaller than an interior dimension of the hollow tubular to generate a pressure drop proximate to said basket member to facilitate separation of the debris from the fluid.

2. An apparatus as recited in claim 1, wherein said basket housing is detachable from the tubular to permit removal of the debris from said interior volume.

3. An apparatus as recited in claim 1, wherein said basket member is substantially cylindrical.

4. An apparatus as recited in claim 1, wherein said basket member further comprises a sloped surface proximate to said aperture for guiding fluid and debris through said aperture.

5. An apparatus as recited in claim 1, wherein said interior volume is substantially toroidal with a closed end and an open end for permitting entry of the debris into said interior volume.

6. An apparatus for capturing debris downhole in a wellbore when fluid is reverse circulated through the wellbore, comprising:

a hollow tubular operable from the wellbore surface;

a cutter head; and

a basket attached between said cutter head and said tubular, wherein said basket comprises an exterior housing and an interior member having an aperture for permitting flow of the fluid and debris therethrough, and wherein said interior member and said exterior housing form an interior volume for capturing the debris as the fluid and debris are reverse circulated through said aperture.

7. An apparatus as recited in claim 6, wherein said basket is detachable from said tubular to facilitate removal of the debris from said basket interior volume.

8. An apparatus as recited in claim 6, wherein said basket is detachable from said cutter head to facilitate removal of the debris from said basket interior volume.

9. An apparatus as recited in claim 6, wherein said interior member is substantially cylindrical.

10. An apparatus as recited in claim 6, wherein said interior member further comprises a sloped surface proximate to said aperture for guiding fluid and the debris through said aperture.

11. An apparatus as recited in claim 6, wherein said interior member further comprises a ring having a threadform for detachable engagement with said exterior housing.

12. A method for capturing debris downhole in a wellbore, comprising the steps of:

attaching a basket housing to a tubular to define an interior volume within said tubular, wherein said basket housing includes an aperture for permitting fluid flow therethrough;

positioning said tubular and basket housing downhole in a wellbore;

reverse circulating fluid to move the debris through said aperture; and

separating the debris from the fluid as the debris and fluid passes through said aperture so that the debris is captured within said basket housing interior volume.

13. A method as recited in claim 12, wherein said basket housing is positioned at a selected location within the wellbore.

14. A method as recited in claim 12, further comprising the steps of withdrawing said basket housing from the wellbore and of removing the debris from said basket housing interior.

15. A method as recited in claim 12, further comprising the steps of operating a mill to generate metal cuttings within the wellbore and of capturing the metal cuttings within said basket housing interior volume.

16. A method as recited in claim 12, further controlling the flowrate of the circulating fluid to control the density of debris captured within said basket housing interior volume.

17. A method as recited in claim 12, further comprising the step of selecting the aperture dimension to control the fluid pressure drop though said aperture as the debris and fluid flows therethrough.

18. A method as recited in claim 12, further comprising the step of selecting the aperture configuration to direct the debris toward said basket housing interior volume.