US20190178047A1

US20190178047A1 - Annular blowout preventer packing element

Info

Publication number: US20190178047A1
Application number: US15/839,342
Authority: US
Inventors: Bradford S. Franks
Original assignee: Axon Pressure Products Inc
Current assignee: Axon Pressure Products Inc
Priority date: 2017-12-12
Filing date: 2017-12-12
Publication date: 2019-06-13

Abstract

An annular blowout preventer (BOP) packing element with improved sealing function and reduced elastomer loss over time is provided. The annular BOP packing element has a bore formed therethrough and includes an elastomer, an array of hardened segments, and an energizer/extrusion ring. The hardened segments are arranged circumferentially about a longitudinal axis of the packing element and bonded to an upper surface of the elastomer. The energizer/extrusion ring is bonded to a lower portion of the elastomer opposite the upper surface of the elastomer.

Description

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to annular blowout preventers, and more specifically, to an improved packing element for an annular blowout preventer.

BACKGROUND

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art.
Blowout preventers are used extensively throughout the oil and gas industry. Typical blowout preventers include a main body to which are attached various types of ram units or packing units. The two categories of blowout preventers that are most prevalent are ram blowout preventers and annular blowout preventers. Blowout preventer stacks frequently utilize both types, typically with at least one annular blowout preventer stacked above several ram blowout preventers. A blowout preventer stack may be secured to a wellhead and may provide a means for sealing the well in the event of a system failure.
Annular blowout preventers generally include annular packing units or packing elements made at least partially from elastomeric material. Upon activation of the annular BOP, the packing element seals the wellbore. The annular blowout preventer typically includes a piston that is actuated (e.g., through pressurized air or fluid) into engagement with the elastomeric packing element. Such activation of the annular packing element compresses the elastomeric material within the annular space until the elastomeric material deforms in a radially inward direction to ultimately seal the wellbore. Metallic or other hardened segments are sometimes included in the annular packing element to help close off the wellbore and guide the elastomer.
Existing annular packing elements can have issues with rubber loss and decreased sealing performance when used over long periods of time. It is now recognized that an annular blowout preventer packing unit with improved sealing function and reduced elastomer loss over time is desired.

SUMMARY

In accordance with an embodiment of the present disclosure, an annular blowout preventer (BOP) packing element having a bore formed therethrough includes an elastomer, an array of hardened segments, and an energizer/extrusion ring. The hardened segments are arranged circumferentially about a longitudinal axis of the packing element and bonded to an upper surface of the elastomer. The energizer/extrusion ring is bonded to a lower portion of the elastomer opposite the upper surface of the elastomer.
In accordance with another embodiment of the present disclosure, a method includes locking and sealing a tubular within an annular blowout preventer (BOP) via a packing element of the annular BOP. The packing element includes an elastomer, an array of hardened segments, and an energizer/extrusion ring. The hardened segments are arranged circumferentially about a longitudinal axis of the packing element and bonded to an upper surface of the elastomer. The energizer/extrusion ring is bonded to a lower portion of the elastomer opposite the upper surface of the elastomer.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an annular blowout preventer, in accordance with an embodiment of the present disclosure;

FIG. 2 is a perspective view of an annular blowout preventer packing element, in accordance with an embodiment of the present disclosure;

FIG. 3 is a top view of the annular blowout preventer packing element of FIG. 2, in accordance with an embodiment of the present disclosure;

FIG. 4 is a cross-sectional view of the annular blowout preventer packing element taken along lines 4-4 of FIG. 3, in accordance with an embodiment of the present disclosure;

FIG. 5 is an expanded cross-sectional view of the annular blowout preventer packing element taken within the dashed lines of FIG. 4, in accordance with an embodiment of the present disclosure;

FIGS. 6A-6D are top, left side, front, and right side views of a hardened segment of the annular blowout preventer packing element of FIGS. 2-4, in accordance with an embodiment of the present disclosure;

FIG. 7 is a perspective cutaway view of certain components of the annular blowout preventer packing element of FIGS. 2-4 along with mold spacer parts used for shaping rubber during formation of the annular blowout preventer packing element, in accordance with an embodiment of the present disclosure;

FIG. 8 is a cross-sectional view of an energizer/extruder ring of the annular blowout preventer packing element of FIGS. 2-4, in accordance with an embodiment of the present disclosure;

FIG. 9A is a top view of the energizer/extruder ring of FIG. 8, in accordance with an embodiment of the present disclosure;

FIG. 9B is a perspective cutaway view of the energizer/extruder ring taken along lines 9B-9B of FIG. 9A, in accordance with an embodiment of the present disclosure; and

FIG. 9C is a perspective cutaway view of the energizer/extruder ring taken within the dashed lines of FIG. 9B, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
Generally, embodiments of the disclosure are directed to an improved packing element that may be utilized in annular blowout preventers. Existing spherical packing elements function such that the elastomer (e.g., rubber) section is compressed and forced radially inward first and the metallic segments close around the tubular later. With this sequence of closing the packing element, there is a race between the elastomer and the metal segments as to which one is located first for sealing the wellbore. This leads to the possibility of parts of the rubber being extruded upward into a position between the tips of the metallic segments and the tubular, which can decrease the sealing function of the packing element.
The disclosed annular packing element overcomes the drawbacks associated with existing packing elements. Specifically, the disclosed packing element is arranged such that the timing of segment closure and rubber sealing is changed. The segment tips of the packing element close the extrusion gap first, and then the elastomer is squeezed in place for sealing.
The disclosed packing element may include an array of hardened metal segments, an elastomer, and an energizer/extrusion ring. The packing element may be a spherical annular packing element. The array of segments may be arranged radially about a longitudinal axis of the packing element and bonded to an upper surface of the elastomer. The energizer/extrusion ring may include an array of fingers projecting radially outward. The energizer/extrusion ring may be constructed from a hardened material and bonded to a lower surface of the elastomer opposite the upper surface of the elastomer. The energizer/extrusion ring may provide additional support to the packing element during actuation of the element into a closed configuration. Specific surfaces of the individual segments and the energizer/extrusion ring may be bonded directly to the elastomer in a manner that prevents the elastomer from extruding into the bore ahead of the segment tips closing. This may improve the sealing function of the packing element and prevent elastomer loss or degradation over long term use of the packing element.
Turning now to the drawings, FIG. 1 is a schematic cross-sectional view of an annular BOP 10 which may employ the disclosed annular packing element 12. The annular BOP 10 may generally include a housing 14, a piston 16 disposed in an annular chamber 18 within the housing 14, and the annular packing element 12. The illustrated annular BOP 10 may be combined with a number of other BOP units arranged in a vertical stack. Such a stack of units is commonly referred to as a BOP stack, and may include one or more ram-type BOPs (not shown) as well as one or more annular BOPs (e.g., 10). As such, FIG. 1 is merely representative of a single annular BOP 10, which may be combined with any number of other BOPs not shown.
The annular BOP 10 generally includes a vertical bore 20 extending therethrough, and a tubular 22 may be disposed within the vertical bore 20. The tubular 22 may form part of a drillpipe, casing, riser, liner, production tubing, coiled tubing, or any other string of tubular that is being positioned within a wellbore below the BOP 10. The BOP 10 is designed to lock the tubular 22 in place and seal the tubular 22 against large pressures from downhole in the event of a kick or other unanticipated event.
The housing 14 may generally enclose the other components of the annular BOP 10. The housing 14 may be one continuous component or may include two or more outer housing components coupled together via appropriate fasteners such as bolts. An upper portion 24 of the housing 14 may have a curved or spherical shape for accommodating the annular packing element 12. Inside the housing 14, the annular packing element 12 is generally positioned above the piston 16, and the piston 16 is at least partially seated within the annular chamber 18.
One or more walls 26 located inside the housing 14 may define the annular chamber 18. As shown, for example, the annular BOP 10 may include a cylindrical wall 26 coupled to and extending upward from a bottom surface of the housing 14 to form a radially internal wall of the annular chamber 18. The rest of the annular chamber 18 may be defined by an external side wall of the housing 14 and the bottom surface of the housing 14, as shown. However, other arrangements of walls, surfaces, and similar components may define the annular fluid chamber 18 in other embodiments. Seals 28 are generally located between the walls of the chamber 18 and the piston 16 disposed therein.
Actuating the annular BOP 10 to close off and seal the tubular 22 generally involves directing pressurized fluid into the chamber 18. This pressurized fluid forces the piston 16 to move upward within the chamber 18. An upper surface 30 of the piston 16 presses directly into the annular packing element 12 in response to this upward movement. This force from the piston 16 compresses the packing element 12 against the surfaces of the housing 14, which direct the packing element 12 to collapse radially inward into locking/sealing engagement with the tubular 22 extending through the BOP 10.
As illustrated, the packing element 12 may be a spherical annular packing element having a rounded or spherical upper surface shape. The packing element 12 of FIG. 1 may include hardened segments bonded to an elastomer and an energizer/extrusion ring, and the arrangement of these components are such that the hardened packing element segments close against the tubular 22 prior to the elastomer portion sealing against the tubular 22. As such, the disclosed packing element 12 may provide an enhanced timing of annular BOP element closure that prevents undesirable elastomer extrusion and degradation.
FIGS. 2-5 illustrate the presently disclosed annular packing element 12 and its constituent components in greater detail. As mentioned above, the annular packing element 12 generally includes a plurality of hardened segments 110, an elastomer 112, and an energizer/extrusion ring 114. The hardened segments 110 are generally arranged in a circumferentially spaced array and are each coupled to an upper surface 116 (FIG. 4) of the elastomer 112. The hardened segments 110 generally form an upper bound of the overall packing element 12. When the packing element 12 of FIG. 2 is assembled into the BOP of FIG. 1, for example, these hardened segments 110 will be the portions of the packing element 12 that directly interface with the upper portion of the housing during actuation of the BOP. The hardened segments 110 have a generally rounded shape at their upper surfaces so as to form a spherical annular packing element 12. The hardened segments 110 may be constructed from any sufficiently hard metallic material including, but not limited to, steel. The material of the segments 110 may be any material that meets the API 164 4th edition 5.3 pressure-containing parts requirements for 60 Ksi to 75 Ksi (see table 1 below) with a chemical composition in accordance with the steel composition limits for pressure-containing parts per table 2 below.

TABLE 1

	Yield Strength		Elongation in	Reduction of
	0.2% Offset	Tensile Strength	50 mm	Area
Material	min.	min.	min.	min.

Designation	MPa	(psi)	MPa	(psi)	%	%

36K	248	(36,000)	483	(70,000)	21	none
						specified
45K	310	(45,000)	483	(70,000)	19	32
60K	414	(60,000)	586	(85,000)	18	35
75K	517	(75,000)	655	(95,000)	18	35
Non-standard	As specified	As specified	As specified	As specified	15	20
Materials

NOTE Information on strength of materials at elevated temperature is found in API 6A and API TR 6MET.

TABLE 2

		Martensitic Stainless
		Steels Limit
Alloying	Carbon and Low-alloy Steels Limit	% Mass Fraction
Element	% Mass Fraction (Maximum)	(Maximum)

Carbon	0.45	0.15
Manganese	1.80	1.00
Silicon	1.00	1.50
Phosphorus	0.025	0.025
Sulphur	0.025	0.025
Nickel	1.00	4.50
Chromium	2.75	11.0 to 14.0
Molybdenum	1.50	1.00
Vanadium	0.30	N/A

The energizer/extrusion ring 114 is located along a lower portion of the overall annular packing element 12, as shown in FIGS. 4 and 5. The energizer/extrusion ring 114 has a relatively flat, annular shape. As shown, a small portion of the elastomer 112 may extend around a lower surface 118 of the energizer/extrusion ring 114 such that the ring 114 is disposed partially within the elastomer 112. In other embodiments, the energizer/extrusion ring 114 may be coupled directly to a lower surface of the elastomer 112 such that the elastomer 112 does not extend around the lower surface 118 of the energizer/extrusion ring 114. In any event, the energizer/extrusion ring 114 may provide a hardened bottom surface to the overall packing element 12 so as to support and direct the extrusion of the elastomer 112 as the piston (16 of FIG. 1) presses upward against the packing element 12. The energizer/extrusion ring 114 may be a single annular shaped piece, and the ring 114 may be constructed from any sufficiently hard metallic material including, but not limited to, steel. The material of the energizer/extruder ring 114 may be any material that meets the API 164 4th edition 5.3 pressure-containing parts requirements for 36 Ksi to 75 Ksi (see table 1 above) with a chemical composition in accordance with the steel composition limits for pressure-containing parts per table 2 above.
The elastomer 112 generally forms a bulk portion of the packing element 12. The elastomer 112 is a single piece of material coupled between the lower surfaces of each of the hardened segments 110 and an upper surface of the energizer/extrusion ring 114. As mentioned above, the elastomer 112 may in some instances be formed entirely around the energizer/extrusion ring 114. The elastomer 112 has a cross-sectional shape that varies at different circumferential positions. The hardened segments 110 may be bonded directly to an upper surface of the elastomer 112 at certain circumferential positions, while the upper surface of the elastomer 112 may be exposed and uncovered at other circumferential positions. The elastomer 112 may be formed into the specific shape for the packing element 12 via a molding process, which will be described in detail below. The elastomer 112 may be made from rubber or any other desirable elastomeric material that is sufficiently compressible for use in the disclosed packing/sealing operation.
Having generally described the components that form the disclosed packing element 12, a more detailed description of the relative shape, dimensions, and arrangement of these components will now be provided.
The packing element 12 includes an array of several segments 110 disposed circumferentially about a longitudinal axis 120 (see FIG. 4) of the packing element 12. As shown in FIGS. 2 and 3, for example, the packing element 12 may include eighteen total segments 110 arranged about the axis 120. The segments 110 may be arranged equidistant from each other around the circumference of the packing element 12, such that the segments 110 are separated from one another by an angle of approximately 20 degrees about the axis 120. Other numbers of segments 110 may be utilized in other embodiments of the packing element 12. Regardless of the number of segments 110 that are arranged within the packing element 12 in total, the segments 110 may be equidistantly arranged about the axis 120 (e.g., 12 segments each separated by 30 degrees, 20 segments each separated by 18 degrees, etc.).
Each of the segments 110 used in the packing element 12 may have a substantially identical shape. However, one or more of the segments 110 may be constructed with a tapped hole 122 formed therethrough. The tapped holes 122 on the upper side of the two segments 110 may be used for mounting lifting components (e.g., hooks or rings) that allow for lifting of the packing element in/out of the BOP. As shown in FIG. 3, the tapped holes 122 may be formed in two of the eighteen total segments 110. These two segments 110 may be located on opposite sides of the packing element 12 from each other. As such, the array of eighteen segments 110 may include one tapped hole segment (110 with hole 122) followed circumferentially by eight regular segments 110 (without a hole), followed by the other tapped hole segment (110 with hole 122) and then the final eight regular segments 110.
FIGS. 6A-6D show detailed views of one of the plurality of segments 110 that have been described above. As illustrated, the segment 110 may be symmetrical with respect to a plane 124. Upon assembly of the segment 110 into the packing element (12 of FIG. 3), this plane 124 is defined by the longitudinal axis 120 of the packing element 12 and a radial line from the axis 120 to a center point of the segment 110.
The segment 110 may include a body portion 126 and an outer flange portion 128. The flange portion 128 curves in an upward direction from a base 130 to a tip 132. The base 130 of the flange portion 128 is located at the furthest radial position from the longitudinal axis of the packing element once assembled, and the tip 132 of the flange portion 128 is located at the closest radial position to the axis. The base 130 of the flange portion 128 is wider in a circumferential direction (width 134) than the tip 132 of the flange portion 128 (width 136). Both sides of the flange portion 128 slope inwardly from the larger width 134 of the base 130 to the smaller width 136 of the tip 132. The flange portion 128 of the segment 110 may have a substantially consistent thickness 138 throughout its entire curved shape.
The flange portion 128 may have a rounded shape that defines the overall spherical profile of the fully assembled packing element. When fully assembled into the packing element, the flange portions 128 of the plurality of segments 110 form the uppermost surfaces of the packing element that directly engage the spherical housing of the annular BOP. The segments 110 are designed to flex radially inward in response to this engagement with the housing so that the tips 132 of the segments 110 are brought into closing contact with the tubular in the BOP before the elastomer comes into sealing contact with the tubular. The tips 132 of the many segments 110, once assembled into the packing element, partially define the bore through the packing element of the BOP.
The body portion 126 of the segment 110 may be entirely aligned with the symmetrical segment plane 124 and may extend along a lower surface 140 of the flange portion 128 from a center point of the tip 132 to a center point of the base 130. The body portion 126 may have a substantially consistent width 142 for its entire surface area. Upon assembly of the segment 110 into the packing element, the body portion 126 generally extends into the elastomer, as opposed to the flange portion 128 which sits atop the elastomer.
In the assembled position, the body portion 126 may be shaped with a first edge 144 that extends in a radially outward and downward direction from the tip 132 of the flange portion 128, and a second edge 146 that extends in a radially inward and upward direction from the base 130 of the flange portion 128. As shown, the two edges 144 and 146 may meet at a point 148 corresponding generally to a midpoint of the spherical curve of the flange portion 128. However, this point 148 may be repositioned in a different location by adjusting the angles of these edges 144 and 146 extending from the tip 132 and the base 130, respectively. In other embodiments, the body portion 126 may feature a curved profile as opposed to the one formed of two relatively straight edges 144 and 146 in the figures.
Turning to FIGS. 8 and 9A-9C, the shape and arrangement of the energizer/extrusion ring 114 will now be described in detail. The energizer/extrusion ring (hereinafter referred to as the “ring”) 114 of the packing element may be a single solid piece as shown. The ring 114 has a shallow cylindrical shape, meaning the ring 114 extends a further distance in an radially outward direction than it extends in a vertical thickness direction (parallel with axis 120). The ring 114 has a bore 210 formed therethrough, and this bore 210 partially defines the bore through the packing element of the BOP. The ring 114 may include a main body 212 immediately surrounding the bore 210 and a plurality of radially extending fingers 214 that extend outward from the main body 212. Between the radially extending fingers 214, a plurality of slots 216 are present. A width 218 of each finger 214 as taken along a circumference of the ring 114 may be larger than a width 220 of each slot 216 between adjacent fingers 214 as taken alone the circumference of the ring 114. The main body 212 of the ring 114 at the location of the bore 210 is thicker in a vertical direction (thickness 222) than a thickness of the fingers 214 (thickness 224). The thickness of the main body 212 may gradually slope from this thickness 222 at the bore 210 to the thickness 224 of the fingers 214, as shown. The thicker main body 212 may help to prevent the elastomer disposed directly above the main body 212 in the fully assembled packer element from extruding into the bore between the actuating piston of the BOP and the tubular.
The extended fingers 214 may provide increased stiffness to the lower portion of the packing element, as well as to distribute upward force from the actuating piston to the packing element in a controlled manner. The number of fingers 214 extending from the main body 212 of the ring 114 may coincide with the number of segments 110 disposed in the packing element. Upon assembly of the packing element, as shown in FIG. 4 for example, the fingers 214 may be circumferentially aligned with respective segments 110 so that each finger 214 is located directly below a corresponding one of the segments 110. This way, upon an upward actuation force acting on the packing element 12, the ring 114 may direct the upward force in a concentrated manner directly to the plurality of segments 110, thereby urging the segments 110 to close against the tubular prior to the elastomer 112 being compressed into sealing engagement with the tubular.
As shown in FIG. 9A, the ring 114 may include two threaded holes 226 formed vertically through the main body 212 of the ring 114. Upon assembly of the packing element, these threaded holes 226 may be disposed directly in alignment with the tapped holes formed through the two segments. The holes 226 may be utilized for removing the assembled packing element out of a mold used in construction of the elastomer. An upper surface 228 of the ring 114 is generally flat so as to provide an appropriate surface for bonding to the elastomer above.
Turning to FIGS. 2-5, a detailed description of the shape of the elastomer 112 will now be provided. The elastomer 112 is located between the ring 114 at the bottom and the plurality of segments 110 at the top. The elastomer may generally be molded into a desired shape and bonded to each of the segments 110 and the ring 114. As illustrated, the elastomer 112 may have a bore 310 formed therethrough. This bore 310 may form part of the overall bore through the packing element 12, along with the tips 132 of the segments 110 and the bore 210 of the ring 114.
Along the bore 310, the elastomer 112 may have a profile defined by a plurality of crests 312 and troughs 314. The crests 312 may each be aligned with the body portion of one of the segments 110, while the troughs 314 may each be located in a circumferential position between two adjacent segments 110. The elastomer 112 may slope radially outward and downward from each of the crests 312 at angles defined by the two corresponding edges 144 and 146 of the segment 110.
The elastomer 112 may similarly slope radially outward and downward from each of the troughs 314. However, the angles and lengths of sloping edges 316 and 318 of the elastomer 112 from the trough 314 to an outer surface of the packing element 12 may be different from the sloping edges from the crest 312 to the outer surface. Specifically, the angles of the sloping edges 316 and 318 of the elastomer 112 may each be larger (as measured from the vertical axis 120) than the corresponding sloping surfaces of the elastomer 112 defined by edges 144 and 146. At a radially outer surface of the packing element 12, a height 320 of the elastomer 112 at a circumferential position corresponding to the crest 312 is smaller than a corresponding height 322 of the elastomer 112 at a circumferential position corresponding to the trough 314. However, other shapes of the elastomer may be possible in other embodiments.
As shown in FIG. 5, a radially internal portion of the elastomer 112 located immediately above the embedded ring 114 may be removed. That is, the bore 310 of the elastomer 112 may have a relatively larger diameter immediately above the ring 114 than it has along the rest of the bore 310. The edges of the annular space 324 formed along the bore 310 of the elastomer 112 may be rounded, as shown. This space 324 within the elastomer 112 may help to prevent the elastomer 112 from extruding into a bore location between the ring 114 and the tubular during actuation of the packing element.
FIG. 4 shows that, upon assembly of the packing element 12, the segment 110 does not form part of a lower surface 412 of the packing element 12 that interfaces with the actuation piston of the BOP. A total vertical height 410 of the segment 110 (from tip 132 to base 130) is shorter than a total vertical height 411 of the elastomer 112 and segment 110 combined (from tip 132 to lower surface 412). The segments 110 do not reach all the way downward into contact with the ring 114 or to a position near where the piston interfaces with the ring 114 and/or elastomer 112. This reduction of height in the segments 110 may prevent undesirable mechanical lockup of the segments 110 with the piston below, as is possible with existing packing elements.
It should be noted that, as illustrated, the edges 144 and tips 132 of the segments 110 are located relatively close to the diameter of the overall bore formed through the packing element 12. For example, the point 148 at which the edges 144 and 146 of the body portion of the segment 110 meet is located a radial distance 414 from the bore of the packing element 12, and this distance 414 is equal to approximately one third of a radial distance 416 from the point 148 to a radially outer edge of the packing element 12. The tip 132 of the segment 110, as shown, actually defines an upper part of the bore through the packing element 12. Because the edges 144 and tips 132 of the segments 110 are located closer to the drift diameter of the packing element 12, the tips 132 are in better position to be quickly closed into engagement with a tubular disposed therethrough before the elastomer 112 below the tips 132 reach the tubular. Instead, the tips 132 will be brought into contact with the tubular first, and the elastomer 112 will then be compressed into sealing engagement with the tubular at locations bounded by the tips 132 at the upper end and by the ring 114 at the lower end of the packing element 12.
FIG. 7 illustrates an arrangement of the ring 114, segments 110, and certain components used during the construction process of the disclosed packing element 12. Specifically, FIG. 7 shows the ring 114 and segments 110 arranged along with spacers 510 that are used during the mold process to shape the elastomer (not shown). Before positioning the components as shown, the process of building the packing element 12 may begin with applying bonding material to surfaces of the segments 110 and ring 114 that will interface directly with the elastomer 112. The surfaces that will receive the bonding material may include the lower surface 140 of the flange portion 128 of each segments 110 (FIG. 6C), as well as the entire body portion 126 of each segment 110 (FIGS. 6B-6D), and the flat upper surface 228 of the ring 114 (FIG. 9A).
After the bonding is applied, the segments 110, ring 114, and spacers 510 are arranged in a mold cavity in the arrangement depicted in FIG. 7. The spacers 510 may sit one between each of the adjacent segments 110. These spacers 510 will define the shape of the elastomer at circumferential positions between the segments 110 (corresponding to the elastomer troughs). The spacers 510 may be integrally formed with the mold cavity or they may be separate parts that are independently positioned within the mold cavity. The segments 110 will be disposed in the mold cavity in positions between the spacers 510. The ring 114 will then be positioned in the mold cavity. The ring 114 will be clocked such that holes 226 through the ring 114 align with the corresponding tapped holes through two of the segments 110. At this point, the mold cavity may be filled with elastomer to complete the formation of the packing element 12.
The presence of the energizer/extrusion ring 114 and having the surfaces of the segments 110 and ring 114 bonded to the elastomer 112 provides extrusion resistance of the elastomer into the bore of the BOP. That is, upper and lower portions of the elastomer do not extrude into positions that are radially between the closed tips 132 and the sealed tubular or radially between the ring 114 (and below piston) and the tubular. This improves the sealing function of the packing element 12 as compared to existing annular packing elements, because more elastomer is available to seal the space between the closed segments tips 132 at the top and the ring 114 at the bottom of the packing element 12. In addition, this lack of undesired elastomer extrusion prevents loss of elastomer from the packing element 12 from long-term use.
While the disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the following appended claims.

Claims

1. An annular blowout preventer (BOP) packing element having a bore formed therethrough, comprising:

an elastomer;

an array of hardened segments arranged circumferentially about a longitudinal axis of the packing element and bonded to an upper surface of the elastomer; and

an energizer/extrusion ring bonded to a lower portion of the elastomer opposite the upper surface of the elastomer, wherein the energizer/extrusion ring is a single annular shaped piece of material that circumferentially surrounds the bore through the BOP packing element.

2. The annular BOP packing element of claim 1, wherein each of the hardened segments comprises a segment tip at its upper end, wherein a radially inner edge of each segment tip defines an upper portion of the bore though the packing element.

3. The annular BOP packing element of claim 1, wherein each of the hardened segments comprises a vertical height that is less than a vertical distance from a lower surface of the elastomer to an upper surface of the hardened segment.

4. The annular BOP packing element of claim 1, wherein each of the hardened segments comprises a body portion extending into the elastomer and a flange portion resting atop the elastomer.

5. The annular BOP packing element of claim 4, wherein the flange portion comprises a base defining a lower edge of the hardened segment and a tip defining an upper edge of the hardened segment.

6. The annular BOP packing element of claim 5, wherein the flange portion is wider in a circumferential direction at the base than at the tip.

7. The annular BOP packing element of claim 4, wherein the body portion comprises a wall defined by two edges extending at different angles from the flange portion into the elastomer, wherein the two edges intersect at a point.

8. The annular BOP packing element of claim 7, wherein the point at which the two edges intersect is located closer in a radial direction to the bore of the packing element than to a radially outer edge of the packing element.

9. The annular BOP packing element of claim 1, wherein the packing element is a spherical packing element and each of the hardened segments has a rounded upper surface.

10. The annular BOP packing element of claim 1, wherein the ring comprises an annular body portion having an annular shape with an inner diameter and an outer diameter, wherein the inner diameter of the annular body portion partially defines the bore of the packing element, and a plurality of fingers extending radially outward from the outer diameter of the annular body portion.

11. The annular BOP packing element of claim 10, wherein each of the fingers is aligned in a radial direction with a corresponding one of the hardened segments.

12. The annular BOP packing element of claim 1, wherein the elastomer comprises a bore formed therethough that forms a portion of the bore of the packing element, wherein, before the elastomer is compressed, the bore of the elastomer has a first diameter along an upper portion of the elastomer and a second diameter at the lower portion of the elastomer directly adjacent an upper surface of the ring bonded to the elastomer, wherein the second diameter is larger than the first diameter.

13. The annular BOP packing element of claim 1, wherein along a portion of the elastomer forming the bore of the packing element, the elastomer has a circumferential profile defined by a plurality of crests and troughs, wherein the elastomer slopes downward from each crest toward two adjacent troughs.

14. The annular BOP packing element of claim 1, wherein the hardened segments are shaped such that, upon actuation of the packing element, the plurality of hardened segments engage a tubular disposed through the bore of the packing element before the elastomer is compressed into engagement with the tubular.

15. A method, comprising:

locking and sealing a tubular within an annular blowout preventer (BOP) via a packing element of the annular BOP, wherein the packing element comprises:

an elastomer;

16. The method of claim 15, wherein locking and sealing the tubular comprises:

closing tips of the plurality of hardened segments in a radially inward direction until the tips contact and close against the tubular; and

after closing the tips, contacting the tubular via the elastomer in a radially collapsed state.

17. The method of claim 16, further comprising transmitting an upward force from a piston of the annular BOP through the energizer/extrusion ring to close the tips of the plurality of hardened segments, wherein the energizer/extrusion ring comprises a plurality of radially extending fingers each disposed beneath a corresponding one of the plurality of hardened segments.

18. The method of claim 15, further comprising preventing extrusion of the elastomer into a space along a bore of the BOP between the packing element and a piston, via the energizer/extrusion ring.

19. The method of claim 18, wherein the elastomer comprises a bore formed therethough, wherein, before the elastomer is compressed, the bore of the elastomer has a first diameter along an upper portion of the elastomer and a second diameter at the lower portion of the elastomer directly adjacent an upper surface of the ring bonded to the elastomer, wherein the second diameter is larger than the first diameter.

20. The method of claim 15, wherein each of the hardened segments comprises a segment tip at its upper end, wherein a radially inner edge of each segment tip defines an upper portion of a bore though the packing element.