AFFIXATION AND RELEASE ASSEMBLY FOR A MILL AND METHOD

Abstract

A downhole affixation and release assembly including a first component; a second component, and an interconnection device for at least temporarily securing the first component to the second component. The interconnection device operatively arranged to at least partially degrade upon exposure to a fluid. Also included is a method of affixing and releasing two components.

Description

BACKGROUND

In the drilling and completions industry it is common to run a whipstock and a mill in the same run by hanging the whipstock from the end of the mill string. Once the whipstock has landed at a selected position and orientation within the borehole, the whipstock is anchored in place and will bear weight. Because the whipstock is necessarily thinner at the uphole end thereof, it has commonly been a practice in the industry to use a relatively large lug at the uphole end of the whipstock to support a set down weight from the mill string that is used to separate the mill from the whipstock, such as by shearing a screw. This arrangement presents a heavy piece of material that must be removed from the path of the mill. Milling the lug often damages the mill due to interrupted cuts, but is nevertheless often performed because of a lack of alternatives. Accordingly, improvements in affixation and release arrangements, particularly for mills, are well received by the industry.

BRIEF DESCRIPTION

A downhole affixation and release assembly includes a first component; a second component, and an interconnection device for at least temporarily securing the first component to the second component, the interconnection device operatively arranged to at least partially degrade upon exposure to a fluid.

A cutting assembly includes a mill operatively arranged to cut through a wall; a whipstock for directing the mill into the wall, the whipstock including an interconnection device for securing the mill to the whipstock during run-in, the interconnection device operatively arranged to at least partially degrade upon exposure to a downhole fluid.

A method of affixing and releasing two components includes, affixing a first component to a second component with an interconnection device; running the first and second components downhole; and degrading the interconnection device by exposing the interconnection device to a fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a schematic view of an affixation and release assembly for a mill;

FIG. 2 is a schematic view of the assembly of FIG. 1 illustrating the mill separated from a whipstock;

FIG. 3 is a schematic view of the assembly of FIGS. 1 and 2 illustrating removal of a lug via a flow of fluid; and

FIG. 4 is a schematic view of the assembly of FIG. 1 illustrating both a lug and a release member being degraded by a flow of fluid.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring now to FIG. 1, an affixation and release assembly 10 is shown, with a mill 12 secured to a whipstock 14 via an interconnection device 15. Throughout the Figures, the mill 12 is shown resembling a tapered starting mill, although it is to be appreciated that other mill types, such as a window mill, could be similarly used. As the end of the whipstock 14 to which the mill 12 is secured is relatively thin, the interconnection device 15 includes a lug 16 affixed to the whipstock 14. The interconnection device 15 also includes a release member 18 extending through the lug 16 in order to secure the whipstock 14 to the mill 12. The releasable member 18 takes the form, for example, of a shear screw, hydraulically actuatable piston or other slidable component, degradable member, etc. The lug 16 is substantially larger than the end of the whipstock 14 and supports the whipstock 14 in order to prevent undue distortion of, or damage to, the whipstock 14 when releasing the mill 12 from the whipstock 14, due to forces exerted on the whipstock 14 while positioning the whipstock 14, etc. However, the lug 16 creates an obstacle to the mill 12 that results in an interrupted cutting operation of the mill 12, as the lug 16 is formed essentially on only one side of the mill 12. The lug 16 can be welded to the whipstock 14, secured to the whipstock 14 via the release member 18, etc. The mill 12 and the whipstock 14 are installed in an annulus 20 formed by a wall 22, which wall could be formed for or by a casing, a borehole, a tubular, cement, a combination of the foregoing, etc.

FIGS. 1-3 show one example of how the assembly 10 can be utilized to release the mill 12. The assembly 10 is shown run in the annulus 20 in FIG. 1, with the mill 12 secured to the whipstock 14 via the release member 18 and the lug 16, as described above. The whipstock 14 is set in position and properly oriented, for example, by use of an anchor assembly or the like (not shown) further downhole in the annulus 20. The whipstock 14 can have a known form, e.g., being a tapered for directing the mill 12 into the wall 22 in order to cut a window or opening in the wall 22. The whipstock 14 could take any other form for, e.g., directing or guiding the mill 12. The mill 12 could similarly take any known form corresponding to the whipstock 14 in order to achieve a window or opening in the wall 22.

After the whipstock 14 and the mill 12 are in place, e.g., by use of an anchor assembly for the whipstock 14, an event is triggered to release the release member 18. For example, if the release member 18 takes the form of a shear screw, applying a set down weight to the mill 12 will shear the release member 18, thereby freeing the mill 12 from the whipstock 14, as shown in FIG. 2. After release of the member 18, the lug 16 presents a significant obstacle to operation of the mill 12. The lug 16 is made from a degradable material in order to remove the lug 16 from the path of the mill 12 without having to mill the lug 16. “Degradable” is intended to mean that the lug is disintegratable, dissolvable, weakenable, corrodible, or otherwise removable. It is to be understood that any use herein of the term “degrade”, or any of its forms, incorporates the stated meaning. In one embodiment, for example, the lug 16 is degraded by exposure to a downhole fluid, such as water, oil, acid, etc. For example, after release of the member 18, as shown in FIG. 3, a flow of fluid 24, is pumped through the annulus 20 or otherwise delivered to the lug 16 in order to degrade the lug. In another embodiment, the mill is hollow or includes a passage therethrough and the flow of fluid is pumped down the mill string to the release member 18 or out an opening proximate to the interconnection device 15. Advantageously, degrading the lug prevents the need for the mill 12 to remove the lug 16 (or the lug is weakened or reduced in size, resulting in easier removal), thereby avoiding potentially significant wear on the mill 12 and extending the life of the mill. Additionally, since removal of the lug does not have to be accounted for, the mill 12 can be more specifically designed to enhance the speed and efficiency with which the mill 12 cuts through the wall 22.

Alternatively, as shown in FIG. 4, the release member 18 could also be made from a degradable material, such that the release member 18 is also degradable, thereby removing another obstacle, although a relatively minor one, from the path of the mill 12. In some embodiments including a degradable release member, the release member 18 is not sheared, but instead, the mill 12 is released from the whipstock 14 by degrading the release member 18 due to exposure to the flow of fluid 24. In other embodiments, the degrading process may weaken the release member before it is sheared or broken by a set down weight. It is to be understood that the same fluid or different fluids could be used to degrade the various components. Thus, the release member 18 could be formed by a rivet, a bolt, a pin, a rod, a plate, or any other element extending between the whipstock 14 and the mill 12, and could either be either integrally formed with the lug 16 (e.g., an extruded rivet) or formed as a separate component. It is to be appreciated that the lug 16 and the release member 18 could be utilized to temporarily connect together other components in a similar way, with the interconnection device 15 (i.e., the lug 16 and/or the release member 18) degrading for enabling relative movement between the components that was previously prevented by the presence of the interconnection device or a portion thereof.

The interconnection device 15 can be formed from materials that are degradable by exposure to a variety of fluids capable of being pumped, present, or delivered downhole such as water, acid, oil, etc. The degradable material could be a metal, a composite, a polymer, etc., or any other material that is suitably degradable and that can withstand the loads necessary to initially hang the whipstock 14 from the mill 12 during run-in, prevent distortion of the whipstock 14 during loading, etc. However, as described above, it may be possible to avoid very high set down loading by simply degrading the release member 18 after the whipstock is locked by the downhole anchor assembly, and thus, the interconnection device 15 may comprise just a release member in some embodiments. In one embodiment, the interconnection device 15, (i.e., the lug 16 and/or the release member 18) is manufactured from a high strength controlled electrolytic metallic material and is degradable by brine, acid, or aqueous fluid.

That is, materials appropriate for the purpose of degradable interconnection devices as described herein are lightweight, high-strength metallic materials. Examples of suitable materials, e.g., high strength controlled electrolytic metallic materials, and their methods of manufacture are given in United States Patent Publication No. 2011/0135953 (Xu, et al.), which Patent Publication is hereby incorporated by reference in its entirety. These lightweight, high-strength and selectably and controllably degradable materials include fully-dense, sintered powder compacts formed from coated powder materials that include various lightweight particle cores and core materials having various single layer and multilayer nanoscale coatings. These powder compacts are made from coated metallic powders that include various electrochemically-active (e.g., having relatively higher standard oxidation potentials) lightweight, high-strength particle cores and core materials, such as electrochemically active metals, that are dispersed within a cellular nanomatrix formed from the various nanoscale metallic coating layers of metallic coating materials, and are particularly useful in borehole applications. Suitable core materials include electrochemically active metals having a standard oxidation potential greater than or equal to that of Zn, including as Mg, Al, Mn or Zn or alloys or combinations thereof For example, tertiary Mg—Al—X alloys may include, by weight, up to about 85% Mg, up to about 15% Al and up to about 5% X, where X is another material. The core material may also include a rare earth element such as Sc, Y, La, Ce, Pr, Nd or Er, or a combination of rare earth elements. In other embodiments, the materials could include other metals having a standard oxidation potential less than that of Zn. Also, suitable non-metallic materials include ceramics, glasses (e.g., hollow glass microspheres), carbon, or a combination thereof In one embodiment, the material has a substantially uniform average thickness between dispersed particles of about 50 nm to about 5000 nm. In one embodiment, the coating layers are formed from Al, Ni, W or Al₂O₃, or combinations thereof In one embodiment, the coating is a multi-layer coating, for example, comprising a first Al layer, a Al₂O₃ layer, and a second Al layer. In some embodiments, the coating may have a thickness of about 25 nm to about 2500 nm.

These powder compacts provide a unique and advantageous combination of mechanical strength properties, such as compression and shear strength, low density and selectable and controllable corrosion properties, particularly rapid and controlled dissolution in various borehole fluids. The fluids may include any number of ionic fluids or highly polar fluids, such as those that contain various chlorides. Examples include fluids comprising potassium chloride (KCl), hydrochloric acid (HCl), calcium chloride (CaCl₂), calcium bromide (CaBr₂) or zinc bromide (ZnBr₂). For example, the particle core and coating layers of these powders may be selected to provide sintered powder compacts suitable for use as high strength engineered materials having a compressive strength and shear strength comparable to various other engineered materials, including carbon, stainless and alloy steels, but which also have a low density comparable to various polymers, elastomers, low-density porous ceramics and composite materials.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

Claims

1. A downhole affixation and release assembly, comprising:

a first component;

a second component, and an interconnection device for at least temporarily securing the first component to the second component, the interconnection device operatively arranged to at least partially degrade upon exposure to a fluid.

2. The assembly of claim 1, wherein the first member is a mill and the second member is a whipstock.

3. The assembly of claim 1, wherein the interconnection device includes a lug secured to the second component.

4. The assembly of claim 3, wherein the lug comprises a high strength controlled electrolytic metallic material and the fluid comprises brine, acid, aqueous fluid, or combinations including at least one of the foregoing.

5. The assembly of claim 1, wherein the interconnection device includes a release member operatively arranged to release the first component from the second component.

6. The assembly of claim 5, wherein the release member releases the first component from the second component by degrading upon exposure to the fluid.

7. The assembly of claim 5, wherein the release member is a shear screw.

8. The assembly of claim 7, wherein the shear screw is operatively arranged to shear after the second component has landed in an annulus and a set down weight has been exerted on the shear screw via the first component.

9. The assembly of claim 8, wherein the release member is degradable upon exposure to the downhole fluid.

10. The assembly of claim 1, wherein the interconnection device is at least partially manufactured from a metal, a composite, a polymer, or combinations including at least one of the foregoing.

11. The assembly of claim 1, wherein the downhole fluid is water, acid, brine, or combinations including at least one of the foregoing.

12. A cutting assembly comprising:

a mill operatively arranged to cut through a wall;

a whipstock for directing the mill into the wall, the whipstock including an interconnection device for securing the mill to the whipstock during run-in, the interconnection device operatively arranged to at least partially degrade upon exposure to a downhole fluid.

13. The assembly of claim 12, wherein the interconnection device comprises a lug secured to the whipstock.

14. The assembly of claim 13, wherein the lug comprises a high strength controlled electrolytic metallic material and the fluid comprises brine, acid, aqueous fluid, or combinations including at least one of the foregoing.

15. The assembly of claim 12, wherein the interconnection device comprises a release member extending between the whipstock and the mill.

16. The assembly of claim 15, wherein the release member is a shear screw operatively arranged to break in response to a set down weight applied to the release member via the mill.

17. A method of affixing and releasing two components comprising:

affixing a first component to a second component with an interconnection device;

running the first and second components downhole; and

degrading the interconnection device by exposing the interconnection device to a fluid.

18. The method of claim 17, further comprising exerting a load on the interconnection device via the first component to release the first and second components.

19. The method of claim 17, wherein the first component is a mill and the second component is a whipstock.

20. The method of claim 19, wherein the interconnection device comprises a lug affixed thereto, the lug being completely degradable by exposure to the fluid.