WO2017218333A1

WO2017218333A1 - Frac plug with retention mechanism

Info

Publication number: WO2017218333A1
Application number: PCT/US2017/036736
Authority: WO
Inventors: Roddie R. Smith; Robert Joe Coon
Original assignee: Petroquip Energy Services, Llp
Priority date: 2016-06-15
Filing date: 2017-06-09
Publication date: 2017-12-21

Abstract

A frac plug is provided. The frac plug may include: a plug body having an outer surface, and including a taper extending along a portion of the outer surface; a sealing element circumferentially disposed about the plug body that, when actuated, seals an annulus between the frac plug and a tubular section; a slip circumferentially disposed about the plug body that, when actuated, engages the tubular section; and a back-up ring circumferentially disposed about the plug body that, when expanded along the taper of the plug body, contacts the tubular section and prevents extrusion of the sealing element.

Description

Frac Plug with Retention Mechanism

[0001] This application claims priority to U .S. Utility Patent Application having Serial No. 1 5/591 ,356 filed May 1 0, 201 7; U.S. Provisional Patent Application having Serial No. 62/350,231 filed on June 15, 201 6, U.S. Provisional Patent Application having Serial No. 62/382,464 filed on September 1 , 2016, and U.S. Provisional Patent Application having Serial No. 62/466,482 filed on March 3, 201 7. These priority applications are hereby incorporated by reference in their entirety into the present application.

[0002] In oil and gas production, it is sometimes beneficial to stimulate a reservoir by pumping in high pressure fluids and particulates, such as sand. In order to do this, one or more tubular sections of a tubular installed in the well may need to be isolated for a period of time and re-opened so the well can be produced. Some current methods of isolation use a frac plug and a sealing ball. A frac plug is a hollow, cylindrical plug that can be installed in the tubular section(s) selected for isolation within the well. The sealing ball then seats in the frac plug to stop fluid flow through the frac plug location and isolate the selected tubular section(s).

[0003] Currently, frac plugs are built around a central mandrel. Typically, the central mandrel is then held in place within a tubular section using upper and lower slips. However, such designs may shift within the tubular section when a sealing ball is installed. Additionally, the sealing element is positioned between the slips. This arrangement may prevent the sealing element from fully compressing if the slips become fully engaged prior to full compression of the sealing element. Further, current frac plugs may allow extrusion of the seal during stimulation of the reservoir, or move as the plug is milled or ground to allow production.

[0004] What is needed, therefore, is a frac plug that can maintain the desired position within the tubular section, ensure full compression of the sealing element, and remain in place during milling or grinding operations.

[0005] Embodiments of the disclosure may provide a frac plug. The frac plug may include a plug body, a sealing element, a slip, and a back-up ring. The plug body may have an outer surface, and include a taper extending along a portion of the outer surface. The sealing element may be circumferentially disposed about the plug body and seal an annulus between the frac plug and a tubular section when actuated. The slip may be circumferentially disposed about the plug body and engage the tubular section when actuated. The back-up ring may be circumferentially disposed about the plug body and expand along the taper of the plug body to contact the tubular section and prevent extrusion of the sealing element.

[0006] Embodiments of the disclosure may further provide a method for setting a frac plug within a tubular section. The method may include positioning the frac plug within the tubular section using a running tool. The method may further include compressing the frac plug with the running tool to engage a slip of the frac plug with the tubular section to retain the frac plug within the tubular section, and to expand a back-up ring along a taper of the frac plug to engage with the tubular section and prevent extrusion of a sealing element.

[0007] Embodiments of the disclosure may further provide a method of assembling a frac plug. The method may include circumferentially disposing a back-up ring about a tapered portion of a first sub of the frac plug. The method may also include circumferentially disposing a slip about the tapered portion of the first sub such that a first axial end of the slip abuts the back-up ring. The method may further include engaging the first sub with a second sub of the frac plug directly or through a lock ring such that the slip is positioned between the back-up ring and the second sub.

Brief Description of the Drawings

[0008] The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0009] Figure 1 illustrates an exemplary frac plug, according to one or more embodiments disclosed.

[0010] Figure 2A illustrates a cross-sectional view of the frac plug of Figure 1 along line 2-2.

[0011] Figure 2B illustrates an enlarged view of the portion of the frac plug indicated by the detail labeled 2B of Figure 2A. [0012] Figure 3A illustrates a cross-sectional view of an exemplary frac plug, according to one or more embodiments disclosed.

[0013] Figure 3B illustrates an enlarged view of the portion of the frac plug indicated by the detail labeled 3B of Figure 3A.

[0014] Figure 4 illustrates a cross-sectional view of an exemplary frac plug, according to one or more embodiments disclosed.

[0015] Figure 5 illustrates the frac plug of Figure 3A being run into the wellbore.

[0016] Figure 6 illustrates the frac plug of Figure 3A as the frac plug is being set in position within a tubular section by a running tool after being run in as shown in Figure 5.

[0017] Figure 7 illustrates the running tool being retracted from the frac plug of Figure 3A after the frac plug is set as shown in Figure 6.

[0018] Figure 8 illustrates the frac plug of Figure 3A in the set position within a tubular section with the running tool fully retracted.

[0019] Figure 9 illustrates the frac plug of Figure 3A once set and sealed. Detailed Description

[0020] It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary 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 exemplary embodiments and/or configurations discussed in the various 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 exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.

[0021] 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. Furthermore, as it is used in the claims or specification, the term "or" is intended to encompass both exclusive and inclusive cases, i.e., "A or B" is intended to be synonymous with "at least one of A and B," unless otherwise expressly specified herein.

[0022] Figure 1 illustrates an exemplary frac plug 100, according to one or more embodiments disclosed. The frac plug 1 00 may include a plug body 1 01 that includes a first sub 102 and a second sub 104. Alternative embodiments of the frac plug 100 may instead include a plug body 101 having a single sub. The frac plug 1 00 may further include a slip 1 06, a sealing element 108, a pump down ring 1 1 0, and a back-up ring 1 12. In at least one embodiment, the external axial ends (one shown 1 14) of the frac plug 100 may include circumferentially spaced, axial protrusions (four shown 1 16), or "castellations", extending from the frac plug 1 00. Other embodiments of the frac plug may have two, three, five, or more castellations 1 1 6 extending from each external axial end 1 14, or the castellations 1 16 may be omitted from one or both of the external axial ends 1 14 of the frac plug 100. The castellated axial ends 1 14 are used in stacking multiple frac plugs 1 00 in a manner known to the art in some embodiments.

[0023] In the exemplary embodiment, the slip 106 includes a plurality of longitudinal, only three of which are shown. The longitudinal grooves 1 18 extend through a portion of the axial length of the slip 1 06. In the exemplary embodiment, adjacent longitudinal grooves 1 18 extend from opposing axial ends 1 20 of the slip 106. In another embodiment, the longitudinal grooves may extend from only one axial end 1 20 of the slip 106. Other embodiments of the slip 1 06 may include two or more adjacent longitudinal grooves 1 1 8 that extend from the same axial end 1 20 of the slip 106, include longitudinal grooves 1 18 that extend axially through the slip 1 06 without interfacing with either axial end 120, or omit the longitudinal grooves 1 18. In the exemplary embodiment, the slip 1 06 also includes a left-hand thread profile 1 22 that is defined in an outer surface 124 of the slip 1 06.

[0024] Figure 2A illustrates a cross-sectional view of the frac plug 100 of Figure 1 along line 2-2. In the exemplary embodiment, the first sub 1 02 includes a cast or powdered metal core 202 bonded to an outer sleeve 204 formed from a resin and fiber composite material. Other embodiments of the first sub 102 may include a core 202 and outer sleeve 204 that are coupled using adhesives, a threaded connection, or both. Still other mechanisms for coupling the core 202 and sleeve 204, such as brazing, welding, and mechanical fasteners, may be used in alternative embodiments. Although the composite material in the exemplary embodiment of the outer sleeve 204 is a resin and fiber composite, other suitable composites known in the art may be used. Additionally, other embodiments of the first sub 102 may be cast or formed from powdered metal , and omit the fiber and resin composite. In another embodiment, the first sub 102 may be formed entirely from a composite material.

[0025] The second sub 1 04 may include a cast or powdered metal core 206 and composite outer sleeve 208, as shown in the exemplary embodiment. The core 206 may be bonded, threadably engaged, or coupled to the outer sleeve 208 using the methods described above. As with the first sub 102, the second sub 104 may be a single component that is cast, formed from powdered metal, or formed from a composite material. When assembled, the core 206 of the second sub 1 04 is partially disposed within the core 202 of the first sub 1 02. As shown Figure 2A, the first core 202 may define an inner thread 21 0 that mates with an outer thread 21 2 of the second core 206 to couple the first sub 102 to the second sub 1 04. [0026] Other embodiments of the frac plug 100 may include a first sub 1 02, a second sub 1 04, or both a first sub 102 and a second sub 1 04 that are predominately composite (i.e., over about 50% composite). In this context, "about" indicates that the measure need not be precisely 50%, but may be more or less depending on a number of factors. For example, variations in manufacturing processes and tools might result in embodiments whose content might deviate from the 50% mark. Similarly, some implementation specific constraints might mitigate for some deviation more or less from a precise 50% composition.

[0027] Another embodiment (not shown) of the frac plug 100 may include first and second subs 102, 104 that are completely composite. As will be appreciated by those skilled in the art, construction of completely composite first and second subs 1 02, 104 might possibly mitigate for a reduction of the inner bore of the frac plug 1 00 to prevent excessive stress in the composite material. Additional embodiments of the frac plug 100 may include first and second subs 1 02, 1 04 that are different materials, such as a cast first sub 1 02 and a composite second sub 1 04. Further embodiments (also not shown) of the frac plug 1 00 may include a single plug body 1 01 that includes a metal core (not shown) bonded, threadably engaged, or coupled to an outer sleeve (not shown) using the methods described above.

[0028] In the illustrated embodiment, the slip 1 06 and back-up ring 1 12 are positioned between the first and second subs 102, 1 04 of the frac plug 100, with the back-up ring 1 12 positioned adjacent the outer sleeve 204 and the slip 1 06. As shown in Figure 2A, a portion of the outer surface 214 of the outer sleeve 204 is tapered. The slip 106, the backup ring 1 12, or both may include a tapered inner surface 21 6, 21 8 that contacts the tapered outer surface 214 of the first sub 102.

[0029] In the exemplary embodiment, the slip 1 06 is made of a powdered metal and the back-up ring 1 1 2 is made of brass. Other embodiments of the slip 106 may be a composite material, cast iron, or any other material known in the art that is suitable for a slip. Additionally, other embodiments of the back-up ring 1 1 2 may be made of titanium or another ductile metal that will allow the back-up ring 1 12 to expand without fracturing.

[0030] Figure 2B illustrates an enlarged view of the portion of the frac plug 1 00 indicated by the detail labeled 2B of Figure 2A. As shown in Figure 2B, each thread 21 3 (only one indicated) of the left-hand thread profile 122 may include a first flank 215 (only one indicated) that is longer than a second flank 217 (only one indicated), angling the crest 219 (only one indicated) of each thread 213 towards the second sub 1 04. Other embodiments may include threads 213 having a first flank 215 and a second flank 217 that are similar in size, and the crest 219 may be perpendicular to the slip 106.

[0031] The back-up ring 1 1 2 may include one or more threads 220 radially extending from the back-up ring 1 12. As shown in Figure 2B, each thread 220 includes a first flank 221 that may be shorter than a second flank 223, angling the crest 225 of each thread 220 towards the first sub 102. In another embodiment, the threads 220 may be replaced by radial protrusions (not shown), or "teeth", having points (not shown) that angle towards the first sub 102. Other embodiments of the back-up ring 1 12 may include threads 220 having crests 225 or teeth having points that are generally perpendicular back-up ring 1 12. Further embodiments of the back-up ring 1 12 may omit the threads 220 and have a smooth outer surface.

[0032] Referring back to Figure 2A, the sealing element 108 may be positioned within an annular recess 222 in the outer surface 214 of the outer sleeve 204. As shown in Figure 2A, the sealing element 108 is independent of the slip 106. This arrangement allows the sealing element 1 08 and the slip 106 to be compressed independently. A compression ring 224 may be coupled to the first core 202 using a threaded connection 226, retaining the sealing element 1 08 in place. Additionally, the pump down ring 1 10 may be positioned within an annular recess 228 defined by the outer sleeve 208 of the second sub 104, as shown in Figure 2A. Other embodiments of the frac plug 100 may omit the pump down ring 1 10, the annular recess 228, or both.

[0033] Figure 3A illustrates a cross-sectional view of an exemplary frac plug 300, according to one or more embodiments. The frac plug 300 illustrated in Figure 3A is an alternative embodiment that may be used in place of the frac plug 100 illustrated in Figures 1 and 2A. The frac plug 300 may be substantially similar in several respects to the frac plug 100 described above with reference to Figures 1 and 2A. Accordingly, the frac plug 300 may be best understood with reference to the frac plug 1 00, where like numerals indicate like elements and therefore will not be described again in detail.

[0034] The first core 202 of the frac plug 300 may have an outer diameter 302 that is smaller than an outer diameter 304 of the outer sleeve 204, as shown in the exemplary embodiment. This may create a recessed portion 306 of the first sub 102 that allows the sealing element 108 to be circumferentially disposed about the first core 202 and adjacent the outer sleeve 204. The frac plug 300 may also include a lock ring 308 positioned between the first core 202 and the second core 206. In the exemplary embodiment, the lock ring 308 is a C-ring type lock ring that includes a gap. Other embodiments of the lock ring 308 may be continuous. The lock ring 308 may define both inner threads 310 and outer threads 31 2.

[0035] In the exemplary embodiment, the outer threads 312 of the lock ring 308 mate with the inner threads 210 of the first core 202, and the inner threads 310 of the lock ring 308 may mate with the outer threads 21 2 of the second core 206. The outer threads 312 of the lock ring 308 and the inner threads 210 of the first core 202 may have a larger pitch than the inner threads 310 of the lock ring 308 and the outer threads 212 of the second core 206, as shown in Figure 3A. In other embodiments, the pitch of the two sets of threads 312, 210, 310, 21 2 may be the same size, or the outer threads 312 of the lock ring 308 and the inner threads 210 of the first core 202 may have a smaller pitch than the inner threads 31 0 of the lock ring 308 and the outer threads 21 2 of the second core 206.

[0036] Figure 3B illustrates an enlarged view of the portion of the frac plug 300 indicated by the detail labeled 3B of Figure 3A. As shown in Figure 3B, the back-up ring 1 12 of the frac plug 300 may be trapezoidal and have a relatively smooth outer surface 314. In the exemplary embodiment, the slip 106 includes a left-hand thread profile 122 where the crest 219 (only one indicated) of each thread 21 3 (only one indicated) is angled towards the second sub 104, as described above. Additionally, a portion of the slip 106 adjacent the back-up ring 1 12 may define one or more threads 31 6. Each thread 316 includes a first flank 317 that is shorter than a second flank 319, angling the crest 321 of each thread 316 towards the first sub 102. In one embodiment, the slip 106 may include a second thread 318 has a larger pitch, a larger pitch diameter, or both a larger pitch and a larger pitch diameter than the other threads 31 6 that have crests 321 angled towards the first sub 102.

[0037] Other embodiments of the slip 106 may include threads 316 that have a pitch, a pitch diameter, or both a pitch and a pitch diameter that are the same size, or a different thread may have a larger pitch, a larger pitch diameter, or both a larger pitch and a larger pitch diameter than the other threads 316. In another embodiment, the threads 31 6 may be replaced by teeth (not shown) having points (not shown) that angle towards the first sub 1 02. Further embodiments of the slip 106 may include a left-hand thread profile 1 22, threads 31 6, or both a left-hand thread profile 1 22 and threads 31 6 that have crests 21 9, 321 that are generally perpendicular to the outer surface 124 of the slip 106.

[0038] It should be appreciated that while the slip 1 06 is particularly well suited to the frac plug 1 00, the present disclosure is not thereby limited. The slip 106 may be used on other frac plugs having a single body, a central mandrel, or more than one slip. Similarly, the slip 1 06 disclosed herein includes features that may readily be applied to slips currently used on other downhole tools.

[0039] Figure 4 illustrates a cross-sectional view of an exemplary frac plug 400, according to one or more embodiments. Although the frac plug 400 in Figure 4 is alternative to the frac plugs 100 and 300 in Figures 1 , 2A, and 3A, it is substantially similar in several respects. Accordingly, like numerals indicate like elements and therefore will not be described again in detail except where material to the present embodiment.

[0040] The first sub 102 of the frac plug 400 may include a cast metallic cap 402 coupled to a resin and fiber composite main body 404, as shown in Figure 4. The cap 402 may be coupled to the main body 404 using adhesives, a threaded connection, or both. Still other mechanisms for coupling the cap 402 and the main body 404, such as bonding and mechanical fasteners, may be used in alternative embodiments. Although the composite material in the exemplary embodiment of the main body 404 is a resin and fiber composite, other suitable composites known in the art may be used. Additionally, other embodiments of the cap 402 may be machined or formed from powdered metal.

[0041] As illustrated in this particular embodiment, the cap 402 may include threads 406 defined in an outer surface 408 of the cap 402. The threads 406 may engage with the compression ring 224 to retain the sealing element 1 08. Additionally, the lock ring 308 may engage with inner threads 41 0 defined by the main body 404 to couple the first sub 1 02 and the second sub 1 04, as shown in Figure 4.

[0042] Figures 5-9 illustrate the installation of the frac plug 300 of Figure 3A. Initially, the frac plug 300 is positioned within a tubular section 502 using a running tool 504 that extends through the frac plug 300, as shown in Figure 5. The frac plug 300 is retained on the running tool 504 by a shear ring 506 configured to break at a predetermined load and a cylindrical retainer 508. The shear ring 506 may be positioned adjacent the second sub 1 04 and the cylindrical retainer 508 may be positioned adjacent the first sub 102. The process of positioning the frac plug 300 within the tubular section 502 may be aided by the pump down ring 1 10, which helps move the frac plug 300 into position within the tubular section 502. Once the frac plug 300 reaches the desired location, the running tool 504 begins to compress the frac plug 300 by pulling the shear ring 506 towards the cylindrical retainer 508 and pushing the cylindrical retainer 508 towards the shear ring 506.

[0043] As shown in Figure 6, the tapered surface 21 4 of the outer sleeve 204 may radially expand the slip 1 06 and back-up ring 1 1 2 as the frac plug 300 is compressed. In some embodiments, this expansion may cause the slip 1 06 to fracture along the longitudinal grooves 1 18, creating a plurality of slip segments (not shown). In other embodiments, the longitudinal grooves 1 18 in the slip 1 06 may allow the slip 106 to expand without fracturing. As the back-up ring 1 12 is made of a ductile material, the back-up ring 1 1 2 expands without fracturing as it moves along the tapered surface 21 4.

[0044] As the frac plug 300 is compressed, the threads 31 6 on the slip 106 that are facing the first sub 102 contact the tubular section 502. The threads 31 6, and, in particular, the larger thread 318, may engage or "bite" into the inner diameter of tubular section 502, preventing further movement of the second sub 1 04 towards the first sub 1 02. Since the frac plug 300 is being compressed by the running tool 504, the cylindrical retainer 508 will continue to push the first sub 102 towards the second sub 1 04. This movement allows the slip 106 and back-up ring 1 12 to continue to move along the tapered surface 21 4 of the outer sleeve 204. The continued expansion of the slip 106 allows the left-hand threads 1 22 of the slip 1 06 to engage with the tubular section 502, preventing movement of the slip 1 06 away from the first sub 102 and further retaining the frac plug 300 in position.

[0045] Additionally, the compression ring 224 shifts along the external threads 602 of the first core 202 as the frac plug is compressed, compressing the sealing element 1 08 and creating a seal between the frac plug 300 and the tubular section 502. The interface between the compression ring 224 and the first core 202 may also have a ratcheting effect, where the threads 604 of the compression ring 224 slide over the external threads 602 of the first core in one direction, but are restricted from moving in the opposite direction by the external threads 602. Accordingly, the ratcheting effect may prevent movement of the compression ring 224 away from the sealing element 1 08 and the outer sleeve 204. Similarly, the lock ring 308 may ratchet along the inner threads 210 of the first core 202, and the second core 206 may ratchet along the inner threads 310 the lock ring 308, preventing decompression of the frac plug 300.

[0046] As shown in Figure 6, the compression ring 224 and sealing element 1 08 are both circumferentially disposed about the first sub 1 02 and separated from the slip 1 06 by the outer sleeve 204. This allows the compressive force applied by the running tool 504 to independently act on the ratcheting interface between the compression ring 224 and the first sub 102, and the ratcheting interface between the first sub 1 02, lock ring 308, and the second sub 104. This arrangement allows the frac plug 300 to continue to compress even if one of the interfaces reaches full compression before the other interface, ensuring the frac plug 300 is fully set within the tubular section.

[0047] As shown in Figure 7, the slip 1 06 may engage with the inner diameter of the tubular section 502 when the frac plug 300 is set, securing the frac plug 300 in place. Additionally, the back-up ring 1 1 2, having expanded into the position shown in Figure 7, contacts the tubular section 502 and may prevent extrusion of the sealing element 108. Once the frac plug 300 is set in position, the shear ring 506 breaks when the predetermined load is reached. The running tool 504 is then tripped out of the tubular section.

[0048] Once the running tool 504 is removed from the frac plug 300 and tubular section 502, as shown in Figure 8, a sealing ball 902 is dropped down the tubular section 502. The sealing ball 902 seats against the inner surface 904 of the first sub 102, as shown in Figure 9, sealing the bore 906 of the frac plug 300. The force of the sealing ball 902 against the first sub 102 of the frac plug 300 may further secure the frac plug 300 in place by shifting the back-up ring 1 1 2 and slip 1 06 further along the tapered surface 21 4 of the first sub 1 02.

[0049] Although not illustrated, it should be understood that the processes of running and setting frac plugs 1 00 and 400 are substantially similar to the process of running and setting frac plug 300. However, the second sub 1 04 of frac plug 1 00 ratchets within the first sub 102 to retain the frac plug 100 in the compressed position , omitting the lock ring 308.

[0050] Once the fracturing operations are complete, the frac plugs 1 00, 300, and 400 may be removed through milling. In embodiments employing a slip 1 06 with a left-hand thread 1 22, the left-hand thread 1 22 of the slip 106 may prevent the frac plug 300 from rotating as the frac plug 100, 300 is being milled, since milling tools typically rotate clockwise. Additionally, the castellations 1 16 in the first and second subs 102, 1 04 of the frac plug 1 00, 300 may allow the frac plug 300 to interface with a second, downstream frac plug 1 00, 300 as it is milled, reducing or eliminating rotational movement of the frac plug 1 00, 300 being milled.

[0051] In addition to the embodiments described above, U.S. Provisional Patent Application Serial Numbers 62/350,231 , 62/382,464, and 62/466,482 incorporated by reference above disclose additional embodiments differing from embodiments described herein in various ways. Although not expressly disclosed herein, these embodiments disclosed in the aforementioned provisional applications are, as previously stated, incorporated by reference into the present application. It is to be understood that the lack of an express disclosure herein does not disclaim such embodiments. Those incorporated embodiments are, through their incorporation, a part of this disclosure as if expressly set forth herein. They therefore are within the scope of the subject matter claimed below.

[0052] As previously noted, the embodiments disclosed in the above provisional applications differ from the embodiments disclosed herein. For example, the embodiment disclosed in Provisional Application 62/350,231 includes a sealing element 108 with an integrated steel back-up ring and pump down ring 1 1 0. The embodiment of Provisional Application 62/350,231 also includes a tapered second sub 104. The embodiment of Provisional Application 62/350,231 further includes a back-up ring 1 12 that is circumferentially disposed about the taper of the second sub and pushes the sealing element 108 up the tapered surface 21 4 of the first sub 1 02 to expand the sealing element 1 08, instead of compressing the sealing element with a compression ring 224. [0053] Additional embodiments, disclosed in Provisional Application 62/382,464, include many of the features disclosed in Provisional Application 62/350,231 . However, one embodiment disclosed in Provisional Application 62/382,464 includes a back-up ring 1 12 that is integral with the slip 106, instead of the sealing element 1 08. Another embodiment disclosed in Provisional Application 62/382,464 includes a slip 106 having a right-hand thread profile defined in the outer surface 1 24 instead of a left-hand thread profile 1 22 to accommodate milling tools that rotate counter-clockwise.

[0054] 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.

Claims

CLAIMS What is claimed is:

1 . A frac plug, comprising:

a plug body having an outer surface, and comprising a taper extending along a portion of the outer surface;

a sealing element circumferentially disposed about the plug body that, when actuated, seals an annulus between the frac plug and a tubular section;

a slip circumferentially disposed about the plug body that, when actuated, engages the tubular section; and

a back-up ring circumferentially disposed about the plug body that, when expanded along the taper of the plug body, contacts the tubular section and prevents extrusion of the sealing element.

2. The frac plug of claim 1 , wherein the back-up ring is fabricated from a ductile metal.

3. The frac plug of claim 2, wherein the back-up ring is fabricated from copper.

4. The frac plug of claim 2, wherein the back-up ring is fabricated from brass.

5. The frac plug of claim 1 , wherein the plug body comprises:

a first sub; and

a second sub.

6. The frac plug of claim 5, wherein the slip is disposed between the first sub and the second sub.

7. The frac plug of claim 6, wherein the sealing element is circumferentially disposed about the first sub.

8. The frac plug of claim 7, further comprising a compression ring circumferentially disposed about the first sub that, when actuated, compresses the sealing element.

9. The frac plug of claim 7, wherein, the back-up ring is disposed between the sealing element and the slip.

1 0. The frac plug of claim 9, wherein a portion of an outer surface of the first sub, the inner surface of the back-up ring, and at least a portion of an inner surface of the slip are tapered.

1 1 . The frac plug of claim 10, wherein the back-up ring and slip are circumferentially disposed about the taper of the outer surface of the first sub.

1 2. The frac plug of claim 5, wherein at least one of the first sub and the second sub is at least partially comprised of a composite material.

1 3. The frac plug of claim 5, wherein the first sub comprises:

a composite material outer sleeve; and

a metal inner core engaged with and structurally supporting the outer sleeve.

1 4. The frac plug of claim 5, wherein the second sub comprises:

a composite material outer sleeve; and

a metal inner core engaged with and structurally supporting the outer sleeve.

1 5. The frac plug of claim 5, further comprising a pump down ring circumferentially disposed about the second sub.

1 6. The frac plug of claim 1 , wherein the plug body comprises a plurality of castellations extending from at least one axial end of the plug body.

1 7 The frac plug of claim 1 , wherein the slip has a first axial end, an outer surface, and an axial length, and defines a left-hand thread pattern in the outer surface extending from the first axial end along a portion of the axial length.

1 8. A method for setting a frac plug within a tubular section, comprising: positioning the frac plug within the tubular section using a running tool; and compressing the frac plug with the running tool to engage a slip of the frac plug with the tubular section to retain the frac plug within the tubular section, and to expand a back-up ring along a taper of the frac plug to engage with the tubular section and prevent extrusion of a sealing element.

1 9. The method of claim 18, wherein the frac plug further comprises a compression ring, and compressing the frac plug with the running tool further comprises ratcheting a compression ring along a threadable engagement with a first sub of the frac plug to compress a sealing element and hold the sealing element in the compressed position.

20. A method of assembling a frac plug, comprising:

circumferentially disposing a back-up ring about a tapered portion of a first sub of the frac plug;

circumferentially disposing a slip about the tapered portion of the first sub such that a first axial end of the slip abuts the back-up ring; and

engaging the first sub with a second sub of the frac plug directly or through a lock ring such that the slip is positioned between the back-up ring and the second sub.