Patent Application
20170260824
A plug is a type of downhole tool that is designed to isolate two (e.g., axially-offset) portions of a wellbore. More particularly, once the plug is set in the wellbore, the plug isolates upper and lower portions of the wellbore while the upper portion is tested, cemented, stimulated, produced, injected into, or the like. The plug may be a bridge plug or a frac plug.
The plug includes one or more slips that are configured to expand radially-outward and into contact with an outer tubular (e.g., a casing) or the wall of the wellbore when the plug is set, to anchor the plug in place. The outer radial surfaces of the slips typically include a plurality of teeth that are configured to “bite” into the outer tubular or the wall of the wellbore to improve the strength of the anchor.
The slips may be made from metal, such as cast iron, or a composite (e.g., fiber-reinforced glass or other such) material. In the latter case, the composite material makes the plug easier to mill out of the wellbore when its use is complete. However, composite materials generally cannot bite into a metal casing (or any other type of surrounding tubular) with sufficient force to resist movement under high pressure. Accordingly, “buttons” made of a harder material, such as carbide or ceramic, are sometimes bonded to the composite slips, which provide the point of contact with the casing. These buttons, however, are prone to detaching from the slips in the well. Further, the size of the buttons is generally constrained, because the buttons can be difficult to mill. The buttons also add to the cost of the plug and complicate the assembly.
An insert for a slip of a downhole tool is disclosed. The insert includes a base, a first button, a second button, and a connecting member. The first and second buttons extend from the base and are configured to engage an inner diameter surface of a tubular. The connecting member extends from the base and is positioned between the first button and the second button.
A slip segment for a downhole tool is also disclosed. The slip segment includes an arcuate body and an insert. The insert includes a base, a first button, a second button, and a connecting member. The base is at least partially embedded within an outer surface of the body. The first button and the second button extend from the base and are configured to engage an inner diameter of a tubular. The connecting member extends outward from the base and is positioned between the first button and the second button.
A method of manufacturing a slip segment for a downhole tool is also disclosed. The method includes positioning an insert in a mold. The insert includes buttons and a connecting member extending between the buttons. A composite material is introduced into the mold. The composite material solidifies after being introduced into the mold and forms an arcuate slip segment made of the composite material. A portion of the composite material is positioned over the connecting member to embed a portion of the insert within the slip segment.
The present disclosure may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:
The following disclosure describes several embodiments for implementing different features, structures, or functions of the invention. Embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference characters (e.g., numerals) and/or letters in the various embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed in the Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the embodiments presented below may be combined in any combination of ways, e.g., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.
Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically, defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. In addition, unless otherwise provided herein, “or” statements are intended to be non-exclusive; for example, the statement “A or B” should be considered to mean “A, B, or both A and B.”
In general, the present disclosure provides a downhole tool, such as a plug, that includes one or more slips. The slips each include a plurality of inserts coupled to (e.g., at least partially embedded within) the outer radial surface thereof. The inserts each include a base, first and second buttons extending outward from the base, and a connecting member extending outward from the base and positioned between the first and second buttons, with, in some embodiments, the base, the first and second buttons, and the connecting member being formed from a single, monolithic piece. The buttons may engage an outer tubular (e.g., a casing) when the slips expand radially-outward.
Turning to the specific, illustrated embodiments,
As shown, the downhole tool 100 may include a body or mandrel 110 having an axial bore 112 formed at least partially therethrough. In at least one embodiment, a solid insert may be positioned in the bore 112 to prevent fluid flow therethrough in both axial directions. In another embodiment, a valve (e.g., a flapper valve) may be positioned in the bore 112 to prevent fluid flow therethrough in only one axial direction while allowing fluid flow in the opposing axial direction. In yet another embodiment, the bore 112 may define a shoulder that is configured to receive an impediment (e.g., a ball) that is introduced into the wellbore from the surface.
A push sleeve 114 may be positioned around the mandrel 110. The push sleeve 114 may be configured to move axially (e.g., downward) with respect with the mandrel 110 to set the downhole tool 100. The push sleeve 114 may also include a locking mechanism designed to prevent the sleeve from moving back (e.g., upward) with respect to the mandrel 110 after the downhole tool 110 is set.
One or more slips (two are shown: 200A, 200B) may also be positioned around the mandrel 110 and below the push sleeve 114. The slips may include a first, upper slip 200A and a second, lower slip 200B. The slips 200A, 200B may include inner surfaces 202A, 202B (
One or more cones (two are shown: 120A, 120B) may also be positioned around the mandrel 110 and between the slips 200A, 200B. The cones may include a first, upper cone 120A and a second, lower cone 120B. The cones 120A, 120B may include outer surfaces 122. At least a portion of the outer surfaces 122 of the cones 120A, 120B may be tapered. As shown, the diameter of the outer surface 122 of the upper cone 120A may increase proceeding downward, and the diameter of the outer surface 122 of the lower cone 120B may decrease proceeding downward. The inner surfaces 202A, 202B of the slips 200A, 200B may be oriented at substantially the same angle as the outer surfaces 122 of the cones 120A, 120B. This may enable the slips 200A, 200B to slide axially-toward one another and radially-outward along the outer surfaces 122 of the cones 120A, 120B as the downhole tool 100 is set.
One or more sealing elements (two are shown: 130, 132) may also be positioned around the mandrel 110. The sealing elements 130, 132 may be positioned axially-between the cones 120A, 120B. The sealing elements 130, 132 may be configured to expand radially-outward and into contact with a surrounding tubular (e.g., casing) or wellbore wall when the downhole tool 100 is set.
A shoe 140 may also be positioned around the mandrel 110. The shoe 140 may be positioned below the push sleeve 114, the slips 200A, 200B, the cones 120A, 120B, and the sealing elements 130, 132. The shoe 140 may be stationary with respect to the mandrel 110. The lower axial surface 142 of the shoe 140 may be tapered.
The upper slip 200A may include a plurality of segments (six are shown: 230) that are circumferentially-offset from one another. As such, axial gaps 232 may be positioned circumferentially-between two adjacent segments 230. In another embodiment, the segments 230 may initially be coupled together but configured to break apart when exposed to a predetermined force (e.g., during setting of the downhole tool 100). Each segment 230 may include one or more rows (two are shown: 220, 222) that are axially-offset from one another with respect to a central longitudinal axis 201 through the upper slip 200A. A circumferential groove 224 may be positioned in the outer surface 204 of the upper slip 200A. and axially-between the two rows 220, 222. In other embodiments, the groove 224 may be in the outer surface 204 and axially-above the rows 220, 222, in the outer surface 204 and axially-below the rows 220, 222. A band (not shown) may be placed at least partially into the circumferential groove 224 to hold the segments 230 in place around the mandrel 110. The band may be configured to break when exposed to a predetermined force during the setting of the downhole tool 100.
At least some of the segments 230 of the upper slip 200A may include one or more buttons 310A, 310B on the outer surface 204 thereof. As shown, each segment 230 that includes buttons 310A, 310B may have, for example, four buttons 310A, 310B (e.g., two buttons in each row 220, 222). As described in greater detail below, the two buttons 310A, 310B in a single row 220, 222 rimybe coupled to or integral with one another, although buttons 310A, 310B in two different rows 220, 222 may also or instead be coupled together or integrally formed. Optionally, at least some of the segments 230 of the upper slip 200A may not include any buttons 310A, 310B. As shown, the segments 230 that include buttons 310A, 310B may alternate with segments 230 that do not include buttons 310A, 310B, as proceeding in a circumferential direction around the upper slip 200A. Thus, in the example shown, the upper slip 200A may include six segments 230, with three of the segments 230 including buttons 310A, 310B. However, in other embodiments, the percentage of segments 230 including buttons 310A, 310B may vary between about 25% and about 100%.
In addition, the lower slip 200B may include a greater percentage of segments 230 that include buttons than the upper slip 200A. This is because the pressure exerted on the downhole tool 100 may be greater above the downhole tool 100 than below the downhole tool 100 once the downhole tool 100 is set. As a result, the lower slip 200B may provide a greater proportion of the anchoring force against the surrounding tubular (e.g., casing) or wellbore wall. As shown, each of the six segments 230 may include four buttons 310A, 310B (e.g., two buttons 310A, 310B in each row 220, 222) However, in other embodiments, the percentage of segments 230 on the lower slip 200B that includes buttons 310A, 310B may vary between about 25% and about 100%.
An axial thickness 314 of the buttons (e.g., with respect to a central longitudinal axis 312 through the buttons 310A, 310B) may decrease proceeding away from the connecting member 340. As such, the buttons 310A, 310B may extend axially-farther from the base 350 proximate to the connecting member 340 than distal to the connecting member 340. The buttons 310A, 310B may optionally have a bore 316 extending from the outer surface 318 toward the base 350. The bore 112 may reduce the amount of material needed to manufacture the buttons 310A, 310B and may facilitate the buttons 310A, 310B breaking up during the milling process. In addition, the bore 316 may be used during the installation of the insert 300 into a mold or onto the slip 200A, 200B.
The connecting member 340 may be coupled to or integral with the buttons 310A, 310B and positioned between the buttons 310A, 310B. The connecting member 340 may be made of the same material as the buttons 310A, 310B (e.g., ceramic material, metal, etc.). An axial thickness 344 of the connecting member 340 may be less than the axial thickness 314 of the buttons 310A, 310B with respect to the central longitudinal axis 312. As such, the buttons 310A, 310B may extend axially-outward farther than the connecting member 340. Said another way, the connecting member 340 may define a recess between the buttons 310A, 310B.
The base 350 may be coupled to or integral with the buttons 310A, 310B and the connecting member 340. The base 350 may be made of composite material, ceramic material, metal, or a combination thereof. The base 350 may extend laterally-outward and/or radially-outward from the buttons 310A, 310B and the connecting member 340 with respect to the central longitudinal axis 312. As such, the base 350 may define a lip 352. The lip 352 may provide a surface area that helps secure the insert 300 in the slip 200A, 200B.
An inner surface 354 of the base 350 may define one or more grooves 356. The grooves 356 may be oriented at an angle 358 with respect to the central longitudinal axis 312. The angle 358 may be from about 10° to about 50°. For example, the angle 358 may be about 30°. The grooves 356 may have a rounded point (e.g., a radius of curvature) or a sharp point. The grooves 356 may reduce the amount of material needed to manufacture the insert 300. In addition, the grooves 356 may act as a stress concentrator that facilitates the insert 300 breaking into smaller pieces when the downhole tool 100 is milled-out of the wellbore.
The outer surface 318 of the button 310A may be rough. For example, a grit (e.g., abrasive particles or granules) may be adhered onto the outer surface 318 to give the outer surface 318 a texture similar to sandpaper. The grit may improve the engagement between the button 3104 and the outer tubular.
The outer surfaces 318 of the buttons 310A, 310B may have a radius of curvature 324 when looking at the view shown in
The size, shape (e.g., angle 322, radius of curvature 324, etc.), number, and positioning of the buttons 310A, 310B on the slip segments 230 may allow the buttons 310A, 310B on the slip segments 230 to have a greater surface area in contact with the outer tubular when compared to conventional slips. Further, the size and shape of the base 350, which may be relatively large in comparison to either one of the buttons 310A, 310B taken alone, may prevent the buttons 310A, 310B from “punching through” the slip segments 230. For example, the geometry of the base 350, including the lip 352 and the grooves 356, may increase the surface area of the inserts 300 that contacts the slip segments 230, which may reduce the likelihood that the insert 300 may punch radially-inward through the slip segment 230.
The method 1600 may then include introducing a composite material into the mold 400, as at 1604. In at least one embodiment, the composite material may be heated when it is introduced into the mold 400. In another embodiment, the composite material may be uncured when introduced into the mold 400. The composite material may form an arcuate slip segment 230 in the mold 400. The inserts 300 may be at least partially embedded within the outer surface 204 of the segment 230. At least a portion of the composite material may solidify over the connecting members 340 of the inserts 300 to at least partially embed the inserts 300 within the segment 230. In addition, at least a portion of the composite material may solidify over the lips 352 of the inserts 300 to embed the inserts 300 within the segment 230. The inserts 300 may be held in place during the molding process by a dowel or rod 402 received through the bore 316. The dowel or rod 402 may be part of the mold 400 or may be a separate component.
The compressive force may cause the sealing elements 150, 152 to expand radially-outward and into contact with an outer tubular (e.g., casing) or the wellbore wall. This may isolate the portions of the annulus (e.g., between the downhole tool 100 and the outer tubular or wellbore wall) above and below the downhole tool 100.
In addition, the compressive force may cause the axial distance between slips 200A, 200B to decrease, and cause the slips 200A, 200B to expand radially-outward. More particularly, the inner surface 202A of the upper slip 200A may slide downward along the outer surface 122 of the upper cone 120A. The tapered arrangement of the surfaces 202A, 122 of the upper slip 200A and the upper cone 120A may cause the upper slip 200A to expand radially-outward as the upper slip 200A moves downward. Similarly, the outer surface 122 of the lower cone 120B may slide downward along the inner surface 202B of the lower slip 200B. The tapered arrangement of the surfaces 202B, 122 of the lower slip 200B and the lower cone 120B may cause the lower slip 200B to expand radially-outward as the lower cone 120B moves downward. The band in the circumferential groove 224 may break as the slips 200A, 200B expand radially-outward.
As mentioned above, the outer surfaces 318 of the buttons 310A, 310B may be oriented. at an angle 322 (e.g., 10.85°) with respect to the central longitudinal axis 201 through the slips 200A, 200B before the downhole tool 100 is set. However, as the slips 200A, 200B expand radially-outward, the thinner axial ends 2108, 212A of the slips 200A, 200B may move radially-outward slightly more than the thicker axial ends 210A, 212B of the slips 200A, 200B This may cause the angle 322 to decrease as the slips 200A, 200B expand radially-outward. The angle 322 may decrease to, for example, about 5° to about −5° with respect to the central longitudinal axis 201 through the slips 200A, 200B. For example, the angle 322 may decrease to about 0° (i.e., parallel to the central longitudinal axis 201 through the slips 200A, 200B). This may increase the surface area of the outer surfaces 318 of the buttons 310A, 310B that contacts the outer tubular (e.g., casing) or wellbore wall, which may increase the anchoring force of the downhole tool 100.
The method 1800 may then include increasing a pressure of a fluid in the wellbore above the downhole tool 100 (e.g., using a pump at the surface), as at 1806. The pressure may be increased to, for example, fracture a portion of the subterranean formation above the downhole tool 100. The method 1800 may then include milling the downhole tool 100 out of the wellbore using a milling tool, as at 1808. As mentioned above, the grooves 356 in the base 350 of the insert 300 may reduce the force necessary to break apart the inserts 300 during milling.
As used herein, the terms “inner” and “outer”; “up” and “down”; “upper” and “lower”; “upward” and “downward”; “above” and “below”; “inward” and “outward”; “uphole” and “downhole”; and other like terms as used herein refer to relative positions to one another and are not intended to denote a particular direction or spatial orientation. The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” refer to “in direct connection with” or “in connection with via one or more intermediate elements or members.”
The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
