Slips are used for various downhole tools, such as composite plugs and packers. The slips can have inserts or buttons to grip the inner wall of a casing or tubular. Examples of downhole tools with slips and inserts are disclosed in U.S. Pat. Nos. 6,976,534 and 8,047,279.
Inserts for slips on metallic and non-metallic tools must be able to engage with the casing to stop the tool from moving during its operation. On non-metallic tools, the inserts can cause the non-metallic slips to fail when increased loads are applied. Of course, when the slip fails, it disengages from the casing.
Inserts for slips are typically made from cast or forged metal, which is then machined and heat-treated to the proper engineering specifications according to conventional practices. When conventional inserts are used in non-metallic slips, they are arranged and oriented as shown in
As shown in both
By providing this angle β, the inserts 24 can better engage the casing wall. For example, when the slip 20 is fully extended to a set position against the casing wall, the inserts 24 inclined by the acute angle β present cutting edges with respect to the inside surface of the casing. With this arrangement, the inserts 24 can penetrate radially into the casing. Angled toward the cones 12, this penetration can provide a secure hold-down against pushing and pulling forces that may be applied through the tool's mandrel 10 and element system.
The arrangement of the inserts 24, however, can damage the slips 20 or the inserts 24 themselves. As shown in
The inserts 24 may also be composed of carbide, which is a dense and heavy material. When the downhole tool having slips 20 with carbide inserts 24 are milled out of the casing, the inserts 24 tend to collect in the casing and are hard to float back to the surface. In fact, in horizontal wells, the carbide inserts may tend to collect at the heel of the horizontal section and cause potential problems for operations. Given that a well may have upwards of forty or fifty composite plugs used during operations that are later milled out, a considerable number of carbide inserts 24 may be left in the casing and difficult to remove from downhole.
The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
The tool T has a mandrel 30 having cones 32 and backup rings 34 arranged on both sides of a packing element 36. Outside the inclined cones 32, the tool T has slips 38 and 40. Together, the slip 38 and 40 along with its corresponding cone 32 can be referred to as a slip assembly, unit, or body, or in other instances, just the slip 38 and 40 may be referred to as a slip assembly, unit, or body. In either case, either reference may be used interchangeably throughout the present disclosure.
As shown herein, the tool T can have two types of slips 38 and 40, one of which may be a conventional wicker slip 38 while the other slip 40 has inserts or buttons 50 according to the present disclosure. It will be appreciated, of course, that both ends of the tool T can have slips 40 with inserts or buttons 50 as proposed herein. Thus, although only one slip 40 with inserts 50 is shown for the upper slip assembly in
As a composite plug, the tool T is preferably composed mostly of non-metallic components according to procedures and details as disclosed, for example, in U.S. Pat. No. 7,124,831, which is incorporated herein by reference in its entirety. This makes the tool T easy to mill out after use.
When deployed downhole, the plug T is activated by a wireline setting tool (not shown), which uses conventional techniques of pulling against the mandrel 30 while simultaneously pushing upper components against the slips 40. As a result, the slips 38 and 40 ride up the cones 32, the cones 32 move along the mandrel 30 toward one another, and the packing element 36 compresses and extends outward to engage a surrounding casing wall. The backup elements 34 control the extrusion of the packing element 36. The slips 38 and 40 are pushed outward in the process to engage the wall of the casing, which both maintains the plug T in place in the casing and keeps the packing element 36 contained.
The force used to set the plug T may be as high as 30,000 lbf. and could even be as high as 85,000 lbf. These values are only meant to be examples and could vary for the size of the tool. In any event, once set, the plug T isolates upper and lower portions of the casing so that frac and other operation can be completed uphole of the plug T, while pressure is kept from downhole locations. When used during frac operations, for example, the plug T may isolate pressures of 10,000 psi or so.
As will be appreciated, any slipping or loosening of the plug T can compromise operations. Therefore, it is important that the slips 38 and 40 sufficiently grip the inside of the casing. At the same time, however, the plug T and most of its components are preferably composed of millable materials because the plug T is milled out of the casing once operations are done, as noted previously. As many as fifty such plugs T can be used in one well and must be milled out at the end of operations. Therefore, having reliable plugs T composed of entirely of (or mostly of) millable material is of particular interest to operators. To that end, the slip assemblies of the present disclosure are particularly suited for such composite plugs T, as well as packers, and other downhole tools, and the challenges they offer.
Contrary to the conventional arrangement of cylindrical shaped inserts disposed at an acute angle toward the inclined end of the slip, the slip 40 of the present disclosure has inserts 50 in an entirely different orientation. As shown in
The second material of the inserts 50 can be can metallic or non-metallic materials. For example, the inserts 50 can be composed of carbide or a metallic-ceramic composite material as conventionally used in the art. Preferably, the inserts 50 are composed of a cast iron, a composite, a ceramic, a cermet (i.e., composites composed of ceramic and metallic materials), a powdered metal, or the like. Additionally, the inserts 50 preferably have a sufficient hardness, which may be a hardness equivalent to about 50-60 Rc.
As shown, the slip body 41 is generally elongated, being longer than it is wide and being relatively thin. Although this configuration is not strictly necessary, the slip body 41 does generally define a body axis or line running longitudinally along its length (e.g., a longitudinal axis LA or centerline). (For the purposes of discussion, the body axis LA of the slip body 41 is referred to herein as the “longitudinal axis.”) The slip's longitudinal axis LA runs parallel to a centerline CL of the tool's mandrel 30, and when the slip 40 is moved for setting against surrounding casing wall, the slip's longitudinal axis LA moves away from the mandrel's centerline CL.
The slip body 41 has inner and outer surfaces 42 and 44 and has first and second ends. The first end is tapered with an incline 43 on the inner surface 42, which engages against the inclined surface 33 of the cone 32, as shown in
When initially run in hole, the slip 40 is disposed with the inner surface 42 adjacent the mandrel 30 of the downhole tool T. During activation, the slip 40 moves away from the mandrel 30 through the interaction of the slip's incline 43 with the cone's inclined surface 33. Rather than having the inserts 50 angled at an angle according to the prior art, the inserts 50 have axes or orientation A angled at a third angle θ3 away from the inclined end of the slip 40. Further details of the arrangement of the inserts 50 are provided below.
As depicted, the inserts 50 have one or more angled or conical surfaces exposed on the slip 40 that allow for proper engagement and load transfer to the casing. As shown in
As is typical, the insert 50 can be constructed from a long, wide bar or rod that is then machined to the prior length and width and given suitable faces. This technique is well suited for carbide or other hard types of materials and may also be used for other disclosed materials. Alternatively, the inserts 50 can be cast directly with the surfaces and size needed, if the material and tolerances allows for it.
In contrast to the flat bottom ends 54, the top end of the insert 50 can have one or more angled faces 56 and 58 on either side of the body's center axis (i.e., the axis A of orientation). A lead face 56, for example, angles from the central axis A at a lead angle α, which creates a wicker edge 57. When exposed in the slip's outer surface, this lead face 56 faces toward the inclined end of the slip 40.
The sharpness of the edge 57 can be increased by a tail face 58 on the insert 50, which can angle from the central axis A at a tail angle φ. The tail face 58 faces toward the butt end of the slip 40, but other arrangements of inserts 50 do not necessarily have such a tail face 58.
These faces 56 can be circular or rectilinear depending on the outer shape of the body 52. Further details of the various angles α and φ, faces 56 and 58, central axis A, and other features of the insert 50 are discussed below.
In the disclosed arrangement of
Looking at the geometric arrangement for the slip assembly in more detail,
As noted above, the top end of the insert 50 is exposed in the outer surface 44 of the slip 40, and the axis of orientation A of the insert 50 is oriented oblique (not perpendicular or parallel) to the longitudinal axis LA of the slip 40 (and by extension to the centerline CL of the assembly (i.e., of the mandrel 30, tool, or the like)). In fact, the axis A is shown oriented at a first obtuse angle σ1 relative to the longitudinal axis LA. Moreover, as specifically shown in the present arrangement, the axis A of the insert 50 is preferably oriented normal to the incline 43 on the slip 40 so that the bottom end 54 of the insert 50 is approximately parallel to the incline 43.
With the insert 50 disposed in the slip 40 normal to the incline 43, the angle α of the lead face 56 is selected based on the angle θ1 of the incline 43 such that the face's angle α defines a second obtuse angle σ2 relative to the longitudinal axis LA. The second obtuse angle σ2 is approximately the sum of 90 degrees, the first angle θ1 of the incline 43, and the angle α of the lead face 56. As shown here, for example, the angle θ1 of the incline 43 can be approximately 15-degrees, and the angle α of the lead face 56 on the insert 50 can be approximately 55-degrees. This would provide the lead face 56 with an angle μ of about 20-degrees outward from the outer surface 44 of the slip 40.
These angles can vary depending on the implementation, the diameter of the tool, the number of inserts 50 in the slip 40, the number of slips 40 used in the assembly, and other factors. In general, an incline angle θ1 of 15-degrees, plus or minus 5-degrees either way may be preferred. Likewise, the angle α of the lead face 56 may be preferably 55-degrees, plus or minus 10 or 15-degrees either way.
As noted above, the axis A of the insert 50 can be normal to the incline 43 on the slip 40 so the axis A will be perpendicular to the cone's inclined surface 33 when engaged thereagainst. Because the slip 40 fits around a cylindrical tool, the slip 40 can define arcuate or partial cylindrical surfaces 42 and 44 as shown in
As noted above, the top end of the insert 50 can have lead and tails faces 56 and 58.
The third insert 503 shows an example lacking a tail face so that the back edge of the insert 503 forms the wicker edge 57 with the lead face 56. Finally, the fourth insert 504 has an angled lead face 56 and a flat tail face 58 that still forms a wicker edge 57. As will be appreciated, the insert 50 of the present disclosure can have these and other configurations.
In fact,
As noted above, various configurations of inserts 50 can be used for the slips 40. To that end,
In
Alternate components can also be incorporated into the arrangement to distribute the load uniformly.
In
The pads 60 and 62 are composed of a third material, which may be different than the materials of the inserts 50 and the slip 40. In general, the third material of the pad 60 and 62 can be a thermoplastic, composite, or any other suitable material. In general, the pad 60 and 62 is preferably a higher strength, denser material than the slip material, which can be a more brittle, injection molded composite. Also, the material of the pads 60 and 62 is preferably millable. As will be appreciated, anywhere from two to five different materials can be utilized for the arrangements of
As shown in the various views of
As shown in
Although all of the inserts 50 are shown symmetrically arranged with their axes angled away from the slip's inclined end, this is not strictly necessary. Instead, some of the inserts (not shown) can be arranged in a conventional manner with the insert's axis angled in an acute angle toward the slip's inclined end, while other inserts 50 can be angled in the manner disclosed herein.
As shown in
In previous arrangements, the slip 40 with inserts 50 is used with a cone 32 on a mandrel of a tool T. As noted previously, the tool T can be a composite plug that can have a packing element for engaging a casing wall. In another arrangement,
In an unset condition shown in
By contrast,
In previous arrangements, the inserts 50 have been discrete elements either disposed and adhered in holes or pockets in the slip body 41 or molded therein. Rather than using singular discrete elements for inserts,
For example,
Lead faces 156 of the inserts 150 are angled to lie at a preferred angle relative to the slip's top surface 44, which in this example has the faces 156 angled up from the top surface by an angle of 20-degrees. Thus, the lead faces 156 define an obtuse angle with the inclined end of the slip 40 that is about 160-degrees. Meanwhile, tail faces 158 of the inserts 150 are at any other acceptable angle to create a wicker edge 157.
In
As already hinted to above, the inserts 150 can be manufactured and affixed to the slip 40 in a number of ways. For example, wires of suitable material can be formed having a desired curvature and the appropriate faces using conventional practices. Then, strips of this wire can be affixed as the inserts 150 in pre-machined lateral grooves 47′ in the top surface 44 of the slip using adhesive or the like. Alternatively, the strips of the wire can be molded as the inserts 150 into the top surface 44 of the slip 40 during a molding process.
Rather than using strips of wire, rings of suitable material can be manufactured with an appropriate diameter for the curvature of the slip assembly. Cut segments of the ring can then be affixed or molded to the slip 40 as the inserts 150. This process may be more suited for some harder materials.
Moreover, rather than being entirely continuous and curved across the outer surface 44 of the slip 40, the inserts 150 can include several, straight sections that are placed about the lateral curvature of the slip 40.
Additional arrangements of slip assemblies having inserts are provided in
The cones 32 have inclined surfaces 33 that face outward and away from the centrally located backup rings 34 and packing element 36. In some embodiments, the inclined surfaces 33 are conical, while the inclined surfaces 33 in other embodiments may be flats as shown. Either type of inclined surfaces 33 can be used.
The upper slip assembly 40U (shown in detail in
As shown, the distal ends of the slip elements 41 are tapered with an incline 43 on the inner surface 42 for engaging against and riding up on the inclined surfaces 33 of the corresponding cone 32. As with the cone's inclined surfaces 33, the inclines 43 on the slip elements 41 can be conical or flats. Either type of inclines 43 can be used.
As also shown, the proximal ends of the slip elements 41 are connected by an interconnected ring portion 49, although this is not strictly necessary on either assembly 40U and 40D as other retention techniques, bands, retainers, or the like can be used.
During setting, the slip elements 41 are movable away from the mandrel 30 through interaction of the elements' inclines 43 with the inclined surfaces 33 of the cones 32. Beyond these similarities, the upper and lower slip assemblies 40U and 40D are different from one another. In particular, each of these upper slip elements 41 has conventional, cylindrical-shaped inserts 24 disposed in the outer surface 44 in a conventional manner. Namely, as best shown in
As will be appreciated, the plug T disposed in a wellbore tubular holds pressure during operations, such as a fracturing treatment. The upper and lower assemblies 40U and 40D may experience different setting movements when the plug T is set and when the assemblies 40U and 40D engage the surrounding tubular wall. Additionally, the upper and lower assemblies 40U and 40D may be subjected to different pressures from above and below the plug T once set and used during operations.
Having the different arrangement of slip inserts 24 and 50 on the upper and lower assemblies 40U and 40D allows operators to tailor the setting and operation of the plug T to meet the needs of a particular implementation. For example, having the normal-oriented inserts 50 on the downhole assembly 40D can be beneficial in some implementations based on the temperatures encountered and the stress on the slip elements 41 and the inserts 50 of the downhole assembly 40D. In one example, a fracture plug may be expected to hold the fracture treatment pressure from above and little to no pressure from below. Such a fracture plug can utilize this embodiment because the stress exerted on the lower assembly 40D is expected to be much greater than the upper assembly 40A. Another benefit is that the conventional inserts on the upper assembly 40U may be a lower cost alternative when compared to normal-oriented inserts on the lower assembly 40D.
As shown in the side view of
As can be seen by the above embodiments, the slip assemblies 40U and 40D on the composite plug T can have different inserts from one another (
For example, all the elements of a slip assembly can have normal-oriented inserts 50 disposed in one row and can have conventional inserts 24 disposed in another row. Other alternates may include: various arrangements and quantities of conventional inserts 24 and normal-oriented inserts 50 on the slip elements 41, differing combinations of normal and conventional inserts 24 and 50 on the upper slip assembly 40U versus the lower slip assembly 40D, or alternating elements 41 of the slip assembly 40 with various arrangements of normal and conventional inserts 24 and 50.
As shown in
As depicted here, alternating elements 41 of the slip assembly 40 have various arrangements of normal and conventional inserts 24 and 50—i.e., one element 41 has all normal inserts 50, the next element 41 has all conventional inserts 24 or some combination of the two inserts 24 and 50, or two adjacent elements 41 have different arrangements of the two types of inserts 24 and 50. The same types of normal-oriented inserts 50 can be used throughout the assembly 40, but this is not strictly necessary. Instead, different types of the normal-oriented inserts 50 disclosed herein can be used on the various elements 41. Moreover, although the arrangement can be symmetrical as shown, this may not be strictly necessary in practice either.
Having the different arrangement of slip inserts 24 and 50 on the assemblies 40 of
In yet another example,
The cones 32 have inclined surfaces 33 that face outward and away from the centrally located backup rings 34 and packing element 36. The slip assemblies 40U and 40D each has slip elements 41 connected at their ends by an interconnected ring portion 49. As shown, the slip elements 41 have conventional, cylindrical-shaped inserts 24 and has normal-oriented inserts 50, and these can be arranged in various different ways, rows, numbers, and/or combinations on the assemblies 40U, 40D to achieve desired purposes.
In the present disclosure, terms such as body, element, and segment may be used for a slip assembly as a whole, for an individual slip, or for one slip of several slips on a slip assembly. Likewise, terms such as assembly, unit, or body may be used interchangeably herein.
In the present disclosure, reference to the tool can refer to a number of downhole tools, such as a plug, a packer, a liner hanger, an anchoring device, or other downhole tool. For example, a composite plug as discussed herein can include a bridge plug, a fracture plug, or a two ball fracture plug. A bridge plug has an integral sealing device completely isolating upper and lower annuluses from either direction when set in casing. A fracture plug typically has one ball that is integral or is dropped on the top of the plug to provide a one way seal from above. Finally, a two ball fracture plug can also be deployed with a lower integral ball that acts to seal pressure from below, but provide bypass from above. A second ball can be dropped or pumped down on top of the plug to seal off pressure above the plug from the lower annulus.
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.
In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.
This application claims the benefit to U.S. Provisional Appl. No. 61/708,597, filed 1 Oct. 2012 and No. 61/735,487, filed 10 Dec. 2012, which are both incorporated herein by reference.
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Number | Date | Country | |
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20140090831 A1 | Apr 2014 | US |
Number | Date | Country | |
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61708597 | Oct 2012 | US | |
61735487 | Dec 2012 | US |