CASING HANGER COMPRESSION RING SYSTEM

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

This Non-Provisional Patent Application is related to and claims the benefit of priority from U.S. Provisional Application No. 63/663,407, titled “CASING HANGER COMPRESSION RING SYSTEM AND METHOD,” filed on Jun. 24, 2024, and incorporated by reference herein in its entirety for all intents and purposes.

BACKGROUND

1. Field of Disclosure

Embodiments of the present disclosure relate to oil and gas tools, and in particular, to systems and methods for compression rings implemented in casing hangers.

2. Description of the Prior Art

In the drilling phase of oil and gas extraction operations, casing hangers allow casing to be set in the wellbore. Casing hangers also connect the casing string to the wellhead and seal the annulus. Within a casing hanger, various seals, including compression seals (also known as compression rings), may be used to seal and maintain the pressure in the annulus. Compression seals are compressed axially to generate a radial sealing force against the casing to prevent a loss of fluid (e.g., oil, gas, solid, or a combination thereof) from the annulus. However, during a blowout, such as occurring from excess downhole pressure, typical compression seals used in a casing hanger may fail by breaking, tearing, leaking, deforming, etc. Moreover, typical compression seals often fail at the cut (the interface at which two or more parts of the seal come together) and at the cap screw holes. What is needed in the industry is a system and method for a compression seal with greater resistance to failure in order to better maintain annulus pressure.

SUMMARY

Applicants recognized the problems noted above herein and conceived and developed embodiments of compression seals, according to the present disclosure, for providing an increased resistance to sealing failure via alternative sealing geometries at the cut between segments of the compression seal.

In an embodiment, a seal for a piece of oil and gas equipment includes a first segment of the seal, a second segment of the seal, a cut defined by the separation in the seal between the first segment and the second segment of the seal, and an interface formable at the cut when a first face of the first segment and a second face of the second segment make contact. The interface formed at the cut increases a surface area of contact between the first segment and the second segment.

In another embodiment, a casing hanger assembly includes a casing hanger housing having a bore extending along a casing hanger axis, one or more top plates axially aligned with the casing hanger housing along the casing hanger axis, one or more bottom plates axially aligned with the casing hanger housing along the casing hanger axis, a seal axially aligned with the casing hanger housing along the casing hanger axis and positioned between the one or more top plates and the one or more bottom plates, and one or more fasteners configured to secure the seal between the one or more top plates and the one or more bottom plates. The seal of the casing hanger assembly includes first segment and a second segment of the seal, a cut defined by the separation in the seal between the first segment and the second segment of the seal, and an interface formable at the cut when a first face of the first segment and a second face of the second segment make contact, the interface increasing a surface area of contact between the first segment and the second segment.

BRIEF DESCRIPTION OF THE DRAWINGS

The present technology will be better understood on reading the following detailed description of non-limiting embodiments thereof, and on examining the accompanying drawings, in which:

FIG. 1A is a perspective view of a compression seal with a failure, in accordance with embodiments of the present disclosure;

FIG. 1B is a perspective and internal view of a compression seal with a failure, in accordance with embodiments of the present disclosure;

FIG. 2 is an exploded isometric view of a casing hanger assembly with a compression seal, in accordance with embodiments of the present disclosure;

FIG. 3A is an isometric view of a compression seal with an embodiment of an upgraded interface, in accordance with embodiments of the present disclosure;

FIG. 3B is an isometric view of a compression seal with another embodiment of an upgraded interface, in accordance with embodiments of the present disclosure;

FIG. 3C is an isometric view of a compression seal with another embodiment of an upgraded interface, in accordance with embodiments of the present disclosure;

FIG. 3D is an isometric view of a compression seal with another embodiment of an upgraded interface, in accordance with embodiments of the present disclosure;

FIG. 3E is an isometric view of a compression seal with another embodiment of an upgraded interface, in accordance with embodiments of the present disclosure;

FIG. 3F is an isometric view of a compression seal with another embodiment of an upgraded interface, in accordance with embodiments of the present disclosure; and

FIG. 3G is an isometric view of a compression seal with another embodiment of an upgraded interface, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

The foregoing aspects, features and advantages of the present technology will be further appreciated when considered with reference to the following description of preferred embodiments and accompanying drawings, wherein like reference numerals represent like elements. In describing the preferred embodiments of the technology illustrated in the appended drawings, specific terminology will be used for the sake of clarity. The present technology, however, is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes equivalents that operate in a similar manner to accomplish a similar purpose.

When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. Additionally, it should be understood that references to “one embodiment”, “an embodiment”, “certain embodiments,” or “other embodiments” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, reference to terms such as “above,” “below,” “upper”, “lower”, “side”, “front,” “back,” or other terms regarding orientation are made with reference to the illustrated embodiments and are not intended to be limiting or exclude other orientations. Moreover, references to “substantially” or “approximately” or “about” may refer to differences within ranges of +/−10 percent.

Embodiments of the present disclosure are directed toward a compression seal to be used in oil and gas equipment, particularly casing hangers. The compression seal may comprise one or more segments, separated by a cut. At the cut of the compression seal, one or more faces of the one or more segments may be designed to form an interface. Embodiments of the present disclosure are directed towards different geometries on the faces of the segments of the compression seal. Different angles, shapes, and patterns on the faces at the cut may better prevent failure (via e.g., breaking, tearing, leaking, deforming, etc.) of the compression seal at the cut. These various embodiments may overcome one or more problems with existing systems, such as systems in which the faces at the interface are merely a straight and flat. Systems and methods discussed herein may address failure of compression seals in casing hangers by having geometries on the faces at the interface that create a tighter seal at the cut between the segments of the compression seal. The embodiments may also increase the sealing surface at the interface, which may eliminate a seal leak path. During situations of excess pressure, the various embodiments discussed herein may be able to better resist the radial blowout at the cut of the compression seal.

FIG. 1A is a perspective view of an embodiment of a compression seal 100 that has had a blowout failure. The compression seal 100 may include a first segment 102 and a second segment 104 (together, “segments,” “portions,” “pieces,” etc.). As illustrated, the segments 102, 104 include one or more seal apertures 106 that may allow the compression seal 100 to be secured to other components via fasteners (not depicted in FIG. 1A), such as cap screws. The compression seal 100 also includes a cut 108, defined as a physical separation between two segments 102, 104 of the compression seal 100. In FIG. 1A, the compression seal also has a blowout 110 at the cut 108, which, as can be seen, comprises a tearing and deformation at the cut 108. The tearing and deformation of the blowout 110 may be defined as a failure of the compression seal 100. The failure of the compression seal 100 due to the blowout 110 may result in a loss of pressure in the equipment in which the compression seal 100 is installed. Pressure from the inside of the compression seal 100 may escape radially through the cut 108 to an external surface 112 of the compression seal 100 and cause the blowout 110 at the external side 112.

FIG. 1B is a perspective view of an embodiment of a compression seal 150 that has had a blowout failure, with segments 102, 104 separated to allow for a view of the cut 108. Additionally, the compression seal 150, similar to compression seal 100 of FIG. 1A, includes one or more seal apertures 106, a blowout 110, and an external surface 112. In the present view of FIG. 1B, a face 152 of segment 104 may be seen. In the embodiment illustrated, the face 152 is a straight and flat surface.

FIG. 2 is an exploded isometric view of an embodiment of a casing hanger assembly 200, which shares several similar features with the compression seal 100 of FIG. 1A and compression seal 150 of FIG. 1B, such as the first segment 102 and second segment 104, and others, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. It should be appreciated that although a casing hanger assembly 200 is depicted, compression seal embodiments of the present disclosure may be used in conjunction with other surface or subsea oil and gas equipment besides casing hangers, such as tubing hangers, Christmas trees (XTs), wellheads, and other equipment. The casing hanger assembly of FIG. 2 includes a casing hanger housing 202 that comprises a casing hanger housing bore 203 extending along a casing hanger axis 204. It should be appreciated that the casing hanger may also be referred to as a slip hanger. The casing hanger housing 202 may comprise housing apertures 206 that may be designed to allow fasteners 208 to secure other components to the casing hanger housing 202.

FIG. 2 also includes a first top plate 210 and a second top plate 212. It should be appreciated that although two top plates 210, 212 are depicted in FIG. 2, there may be any reasonable number of top plates. The first top plate 210 and the second top plate 212 may be configured to fit together such that bringing the top plates 210, 212 together on the same plane and aligning the edges of the top plates 210, 212 creates substantially a single circular top plate. Also illustrated in FIG. 2 is a first bottom plate 214 and a second bottom plate 216. It should similarly be appreciated that although two bottom plates 214, 216 are depicted in FIG. 2, there may be any reasonable number of bottom plates. The first bottom plate 214 and the second bottom plate 216 may be configured to fit together such that bringing the bottom plates 214, 216 together on the same plane and aligning the edges of the bottom plates 214, 216 creates substantially a single circular bottom plate.

Additionally, the first segment 102 and second segment 104 of the compression seal may be configured to fit together such that bringing the segments 102, 104 together on the same plane and aligning/fitting together the first faces 218 of the first segment 102 with the second faces 220 of the second segment 104 creates substantially a single circular compression seal. The faces 218, 220 may have different geometries, as will be explained further in connection with FIGS. 3A-3G. It should be appreciated that although as depicted in FIG. 2, there are just two segments 102, 104 coming together to form a single compression seal, there may be any reasonable amount of segments per compression seal, as well as any reasonable amount of circular compression seals included in the casing hanger assembly 200.

Furthermore, in the casing hanger assembly 200 that is fully assembled, the top plates 210, 212, the compression seal segments 102, 104, and the bottom plates 214, 216 may be in axial alignment with the casing hanger housing 202 along the casing hanger axis 204. Also in the fully assembled assembly, the top plates 210, 212, compression seal segments 102, 104, and bottom plates 214, 216 each create substantially a single circular plate or seal, as applicable. The compression seal segments 102, 104 may be positioned and secured between the top plates 210, 214 and the bottom plates 214, 216.

Moreover, the top plates 210, 212 may include one or more top plate apertures 222 and the bottom plates 214, 216 may include one or more bottom plate apertures 224. The top plate apertures 222, the seal apertures 106, and the bottom plate apertures 224 may be aligned with the housing apertures 206 circumferentially along the casing hanger axis 204. When the all of the apertures 222, 106, 224, 204 are aligned, the fasteners 208 may be able to extend through the apertures 222, 106, 224, 204 in order to secure the top plates 210, 212, compression seal segments 102, 104, and bottom plates 214, 216 to the casing hanger housing 202. Fastening the top plates 210, 212, compression seal segments 102, 104, and bottom plates 214, 216 to the casing hanger housing 202 using the fasteners 208 compresses the compression seal segments 102, 104, sealing a leak path. Used in conjunction with the fasteners 208 to secure the plates, compression seal, and housing together, may be engaging rings 226 and/or nuts, which also may be aligned with the apertures 222, 106, 224, 204 circumferentially along the casing hanger axis 204 and the fasteners 208 may extend through the rings 226.

FIG. 3A is an isometric view of an embodiment of a compression seal 300, which shares several similar features with the compression seal 100 of FIG. 1A, the compression seal 150 of FIG. 1B, and the casing hanger assembly 200 of FIG. 2, such as the first segment 102, second segment 104, one or more seal apertures 106, cut 108, and external surface 112, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. The compression seal 300 may include a first face 301 of the first segment 102 and a second face 302 of the second segment 104. As illustrated, the first face 301 can include at least one recess 304, and the second face 302 can include at least one protrusion 306 corresponding to the recess 304 such that the recess 304 is configured to receive the protrusion 306 when the first and second faces 301, 302 engage. In the specific embodiment shown in FIG. 3A, there are depicted two recesses 304 and two protrusions 306, but any appropriate number of recesses 304 and protrusions 306 can be used.

When the first segment 102 is brought together with the second segment 104 so that the first face 301 makes contact with the second face 302, it may form an interface at the cut 108 of the compression seal 300. It may be the case that the more recesses and protrusions 304, 306 there are in the faces 301, 302, the larger the surface area of the interface is, which may increase the ability for the compression seal 300 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 300. It should be appreciated that although in FIG. 3A, the recesses and protrusions 304, 306 in the faces 301, 302 are radially aligned with the external surface 112 of the compression seal 300, the recesses and protrusions 304, 306 may be directed at any angle relative to the external surface 112. The geometry of the faces 301, 302 at the interface, here being the recesses and protrusions 304, 306, may be able to better prevent failure of the compression seal 300.

FIG. 3B is an isometric view of an embodiment of a compression seal 310, which shares several similar features with the compression seals 100, 150, 300 of FIG. 1A, 1B, 3A, respectively, and the casing hanger assembly 200 of FIG. 2, such as the first segment 102, second segment 104, one or more seal apertures 106, cut 108, and external surface 112, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. The compression seal 310 may include a first face 311 of the first segment 102 and a second face 312 of the second segment 104. As illustrated, the first face 311 includes two wide recesses 314, and the second face 312 includes two wide protrusions 316. It should be appreciated that although only two wide recesses and protrusions 314, 316 are depicted in FIG. 3A, there may be any reasonable number of recesses and protrusions 314, 316.

When the first segment 102 is brought together with the second segment 104 so that the first face 311 engages the second face 312, such engagement can form an interface at the cut 108 of the compression seal 310. It may be the case that the more wide recesses and protrusions 314, 316 there are in the faces 311, 312, the larger the surface area of the interface is, which may increase the ability for the compression seal 310 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 310. It should be appreciated that although in FIG. 3B, the wide recesses and protrusions 314, 316 in the faces 311, 312 are radially aligned with the external surface 112 of the compression seal 310, the wide recesses and protrusions 314, 316 may be directed at any angle relative to the external surface 112. The geometry of the faces 311, 312 at the interface, here being the wide recesses and protrusions 314, 316, may be able to better prevent failure of the compression seal 310.

FIG. 3C is an isometric view of an embodiment of a compression seal 320, which shares several similar features with the compression seals 100, 150, 300, 310 of FIG. 1A, 1B, 3A, 3B, respectively, and the casing hanger assembly 200 of FIG. 2, such as the first segment 102, second segment 104, one or more seal apertures 106, cut 108, and external surface 112, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. The compression seal 320 may include a first face 321 of the first segment 102 and a second face 322 of the second segment 104. As illustrated, the first face 321 includes first grooves 324, and the second face 322 includes second grooves 326.

When the first segment 102 is brought together with the second segment 104 so that the first face 321 makes contact with the second face 322, it may form an interface at the cut 108 of the compression seal 310. The first grooves 324 and second grooves 326 may be designed to fit together flush, forming a gap-free interface at the cut 108. It may be the case that the more first and second grooves 324, 326 there are in the faces 321, 322, the larger the surface area of the interface is, which may increase the ability for the compression seal 320 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 320. Additionally, it may be the case that the deeper the first and second grooves 324, 326 are, the larger the surface area of the interface is, which may increase the ability for the compression seal 320 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 320. It should be appreciated that although in FIG. 3C, the grooves 324, 326 in the faces 321, 322 are radially aligned with the external surface 112 of the compression seal 320, and the grooves 324, 326 may be directed at any angle relative to the external surface 112. The geometry of the faces 321, 322 at the interface, here being the first and second grooves 324, 326, may be able to better prevent failure of the compression seal 320.

FIG. 3D is an isometric view of an embodiment of a compression seal 330, which shares several similar features with the compression seals 100, 150, 300, 310, 320 of FIGS. 1A, 1B, 3A, 3B, 3C, respectively, and the casing hanger assembly 200 of FIG. 2, such as the first segment 102, second segment 104, one or more seal apertures 106, cut 108, and external surface 112, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. The compression seal 330 may include a first face 331 of the first segment 102 and a second face 332 of the second segment 104. As illustrated, the first face 331 includes two first recesses 334, and the second face 332 includes two second recesses 336. It should be appreciated that although only two recesses 334, 336 are depicted in each of the faces 331, 332 in FIG. 3D, there may be any reasonable number of recesses 334, 336. The compression seal 330 also may include one or more seal members 338, which may each be configured to fit within the first recess 334 of the first face 31 and the second recess 336 of the second face 332.

When the first segment 102 is brought together with the second segment 104 so that the first face 331 makes contact with the second face 332, it may form an interface at the cut 108 of the compression seal 330. It may be the case that the more recesses 334, 336 and seal members 338 there are in the faces 331, 332, the larger the surface area of the interface is, which may increase the ability for the compression seal 330 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 330. It should be appreciated that although in FIG. 3D, the recesses 334, 336 and seal members 338 are radially aligned with the external surface 112 of the compression seal 330, the recesses 334, 336 and seal members 338 may be directed at any angle relative to the external surface 112. The geometry of the interface, here being the recesses 334, 336 and seal members 338, may be able to better prevent failure of the compression seal 330.

FIG. 3E is an isometric view of an embodiment of a compression seal 340, which shares several similar features with the compression seals 100, 150, 300, 310, 320, 330 of FIGS. 1A, 1B, 3A, 3B, 3C, 3D, respectively, and the casing hanger assembly 200 of FIG. 2, such as the first segment 102, second segment 104, one or more seal apertures 106, cut 108, and external surface 112, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. The compression seal 340 may include a first face 341 of the first segment 102 and a second face 342 of the second segment 104. As illustrated, the first face 341 is concave with the point of curvature originating at the external side surfaces 112 of the seal 340, and the second face 342 is convex. As such, the linear portions of the cut 108 exist on the external side surfaces 112 of the seal 340 and may extend perpendicular to the internal diameter of the seal 340. It should be appreciated that the compression seal 340 of FIG. 3E may be referred to as a “vertical configuration,” as compared to a “horizontal configuration” of the compression seal 360 of FIG. 3G (discussed below). The concave first face 341 is configured to engage the convex second face 342 along substantially the entire surface area of the first face 341 and the second face 342. It should be appreciated that although the faces 341, 342 have a curved parabolic shape, the faces 341, 342 may have any type of curved or wave shape.

When the first segment 102 is brought together with the second segment 104 so that the first face 341 makes contact with the second face 342, it may form an interface at the cut 108 of the compression seal 340. It may be the case that the more dramatic the curve of the faces 341, 342 are, the larger the surface area of the interface is, which may increase the ability for the compression seal 340 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 340. The geometry of the interface, here being the vertical parabolic curved faces 341, 342, may be able to better prevent failure of the compression seal 340.

FIG. 3F is an isometric view of an embodiment of a compression seal 350, which shares several similar features with the compression seals 100, 150, 300, 310, 320, 330, 340 of FIGS. 1A, 1B, 3A, 3B, 3C, 3D, 3E, respectively, and the casing hanger assembly 200 of FIG. 2, such as the first segment 102, second segment 104, one or more seal apertures 106, cut 108, and external surface 112, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. The compression seal 350 may include a first face 351 of the first segment 102 and a second face 352 of the second segment 104. As illustrated, the first face 351 includes two first angled portions 353 and one first flat portion 354, and the second face 352 includes two second angled portions 356 and one second flat portion 357. It should be appreciated that although two angled portions 353, 356 and one flat portion 354, 357 are included in each of the faces 351, 352 as depicted in FIG. 3F, there may be any reasonable number of angled portions 353, 356 and flat portions 354, 357. For example, in each face there may be one angled portion and two flat portions, or four angled portions and three flat portions, or three angled portions and three flat portions, or any other reasonable combination. Additionally, the angled portions 353, 356 may be at any reasonable angle oblique to the flat portions 354, 357.

When the first segment 102 is brought together with the second segment 104 so that the first face 351 makes contact with the second face 352, it may form an interface at the cut 108 of the compression seal 350. It may be the case that the more angled portions 353, 356 and flat portions 354, 357 there are in the faces 351, 352, the larger the surface area of the interface is, which may increase the ability for the compression seal 350 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 350. The geometry of the interface, here being the angled portions 353, 356 and flat portions 354, 357, may be able to better prevent failure of the compression seal 350. In FIG. 3F, the angled portions 353, 356 are positioned adjacent to the external surfaces 112 of the compression seal 350. As such, the linear portions of the cut 108 exist on the external side surfaces 112 of the seal 350 and may extend perpendicular to the internal diameter of the seal 350. It should be appreciated that the compression seal 350 of FIG. 3F may be referred to as a “vertical configuration” of the compression seal 350.

One would appreciate that the seal 350 may also be in a “horizontal configuration” where the angled portions 353, 356 are positioned adjacent to the top and bottom surfaces of the compression seal 350. As such, the linear portions of the cut 108 would exist on the top and bottom surfaces of the seal 360 and may extend horizontally and along the internal diameter of the seal 360. It should be appreciated that this compression seal may be referred to as the “horizontal configuration,” as compared to the “vertical configuration” of the compression seal 350 of FIG. 3F. In other words, one would appreciate that this “horizontal configuration,” as compared to the “vertical configuration” of the compression seal 350 of FIG. 3F is similar to how the compression seal 340 of FIG. 3E is the “vertical configuration” as compared to the “horizontal version” of the compression seal 360 of FIG. 3G. The difference here being the shaped surfaces of the faces of the two pairs of compression seals (i.e., angled and flat portions, versus concave and convex portions).

FIG. 3G is an isometric view of an embodiment of a compression seal 360, which shares several similar features with the compression seals 100, 150, 300, 310, 320, 330, 340, 350 of FIGS. 1A, 1B, 3A, 3B, 3C, 3D, 3E, 3F, respectively, and the casing hanger assembly 200 of FIG. 2, such as the first segment 102, second segment 104, one or more seal apertures 106, cut 108, and external surface 112, which will be identified with like reference numerals for convenience purposes only and not to limit the scope of the present disclosure. The compression seal 360 may include a first face 361 of the first segment 102 and a second face 362 of the second segment 104. As illustrated, the first face 361 is concave with the points of curvature originating at the top and bottom surfaces of the seal 360, and the second face 362 is convex. As such, the linear portions of the cut 108 exist on the top and bottom surfaces of the seal 360 and may extend horizontally and along the internal diameter of the seal 360. It should be appreciated that the compression seal 360 of FIG. 3G may be referred to as the “horizontal configuration,” as compared to the “vertical configuration” of the compression seal 340 of FIG. 3E. The concave first face 361 is configured to engage the convex second face 362 along substantially the entire surface area of the first face 361 and the second face 362. It should be appreciated that although the faces 361, 362 have a curved parabolic shape, the faces 361, 362 may have any type of curved or wave shape.

When the first segment 102 is brought together with the second segment 104 so that the first face 361 makes contact with the second face 362, it may form an interface at the cut 108 of the compression seal 360. It may be the case that the more dramatic the curve of the faces 361, 362 are, the larger the surface area of the interface is, which may increase the ability for the compression seal 360 to prevent leaks from seeping through the interface of the cut 108 to the external surface 112 of the compression seal 360. The geometry of the interface, here being the horizontal parabolic curved faces 361, 362, may be able to better prevent failure of the compression seal 360.

Although the technology herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present technology. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present technology as defined by the appended claims.