Patent Application
20200173247
This disclosure relates in general to oil and gas tools, and in particular, to systems and methods for sealing between components in wellbore operations.
In oil and gas production, different pieces of equipment may be utilized in a downhole environment in order to isolate sections of a wellbore. For example, casing may be installed along an outer circumferential extent of the wellbore and additional equipment, such as hangers and the like, may be installed within the wellbore. The hanger may be used to support wellbore tubulars utilized within the system. In operation, seals (e.g., elastomeric, metal, etc.) may be arranged between the downhole components in order to establish pressure barriers in order to direct fluid into and out of the well along predetermined flow paths. Seals may be “U” shaped and energized via an energizing ring that is driven into the U-opening to provide pressure to drive the seals against the wellbore components. The energizing ring is typically driven into position using setting tools that rely on bore pressure, which may be limited due to other equipment used at the site, such as blowout preventers (BOPs).
Applicant recognized the limitations with existing systems herein and conceived and developed embodiments of systems and methods, according to the present disclosure, to improve the systems by reducing setting loads for downhole sealing systems.
In an embodiment, an energizing ring for setting a downhole seal includes a body having a varied cross-section along at least a portion of an axial length. The energizing ring also includes a plurality of peaks forming at least a portion of the varied cross-section having a first diameter. The energizing ring also includes a plurality of valleys forming at least a portion of the varied cross-section having a second diameter, the first diameter being larger than the second diameter, and respective valleys of the plurality of valleys being arranged proximate respective peaks of the plurality of peaks.
In an embodiment, a system for forming a seal between downhole components includes a seal arranged between at least two downhole components. The seal includes a first leg and a second leg, each leg positioned proximate one of the at least two downhole components, wherein the first and second legs engage the at least two downhole components upon activation of the seal. The system also includes an energizing ring to activate the seal. The energizing ring extends into an opening of the seal to drive the first leg and the second leg radially outward relative to an axis of the energizing ring. The energizing ring includes a plurality of geometric features, forming a varied cross-section, that sequentially contact the seal when the energizing ring is installed within the opening, wherein respective geometric features of the plurality of geometric features form areas of high and low concentrations of pressure that alternate axially along a length of the energizing ring when installed within the opening.
In an embodiment, a method for setting a downhole seal includes arranging a seal within a wellbore between at least two wellbore components. The method also includes aligning an energizing ring with an opening of the seal. The method further includes driving the energizing ring into the opening of the seal to deform the seal. The method includes engaging legs of the seal with a plurality of geometric features formed on the energizing ring, the geometric features reducing a contact area between the legs and the energizing ring.
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:
The foregoing aspects, features, and advantages of the present disclosure will be further appreciated when considered with reference to the following description of embodiments and accompanying drawings. In describing the embodiments of the disclosure illustrated in the appended drawings, specific terminology will be used for the sake of clarity. However, the disclosure 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 or direction are made with reference to the illustrated embodiments and are not intended to be limiting or exclude other orientations or directions.
Mechanically energized U-cup type metal annular pack offs are set by forcing an actuating energizing ring into the inside of a U-cup sealing element. The energizing ring expands the sealing element into the seal pocket and provides mechanical preload into the sealing surfaces. This mechanical preload provides the contact pressure for containing pressure. The setting load is a function of two components: 1) the friction between the energizing ring and the U-cup seal interfaces, and 2) the energy to provide compression preload on the sealing surface. The compression load is designed to provide a predetermined amount of contact pressure to form a metal-to-metal seal. Accordingly, it is not desirable to lower the compression load so that the setting load can be optimized.
Embodiments of the present disclosure lower the frictional load between the energizing ring and the sealing element via a series of geometrical features. In various embodiments, the geometric features may include a set of bumps, a set of tapers and flats, or a combination thereof. As a result of small contact areas between the interface, the setting load is reduced. In other words, setting loads are decreased as the radial clamping force or frictional load that the energizing ring applies to the sealing element is reduced at valleys or pockets formed between the geometric features. Moreover, in various embodiments, less strain energy is transmitted to the sealing element because there is less expansion at certain areas. Accordingly, the setting load may be reduced because of a reduction in friction load. However, this reduction in friction load may be caused by a reduction in energy to expand the seal because the non-contact points between the geometric features may lead to less energy to expand the seal. That is, less energy to expand the seal may correspond to a lower radial load, which may further correspond to less normal load. This normal load may be correlated to friction. Therefore, in embodiments, the reduction in energy to expand the seal may also correspond to a reduced frictional load. Furthermore, in various embodiments, local increases in mechanical advantage may further reduce the loads. As the energizing ring enters the sealing element, the first set of geometrical features (e.g., bumps/tapers) contacts the sealing element. This causes the sealing element to expand. As the energizing ring is driven further into the sealing element, each bump/taper in the series sequentially makes contact and preloads the sealing element. The bumps/tapers may be sized such that only the crest (e.g., highest part) maintains contact with the sealing element. This reduction in contact area reduces the overall frictional loads due to the reduced radial contact loads, as described above. In other words, the geometrical features form localized points of interference, rather than a continuous interface along a length of the energizing ring. Moreover, it should be appreciated that while embodiments of the present disclosure may include a plurality of geometric features, in various embodiments, a single geometric feature may be utilized. In various embodiments, lubricious coatings may further be integrated in order to enhance the frictional reduction.
In various embodiments, setting a mechanically energized metal seal uses large settings loads. As described above, these loads are the result of the friction between the energizing ring and the sealing element, as well as the preload to form a seal. In the operational case, where the seal is run with a tool that uses bore pressure, the maximum pushing capacity may be limited by a blowout preventer (BOP) or other wellhead components. For example, the annular/pipe rams of the BOP are closed and the annular void between the tool and the BOP is pressurized. This pressure applies a piston force to the tool, which sets the seal. If the seal is set in a lower pressure rated wellhead, and the BOP is downsized for cost, it is possible that the annular tool pressure may not be sufficient to set the seal. Embodiments of the present disclosure reduce the setting load of the seal without compromising the sealing capability. As a result, the seal can be set in more scenarios, and the tools can be downsized. Furthermore, in various embodiments, reducing the setting load may enable design of tools with more contact pressure to provide enhanced sealing capabilities using existing setting equipment.
In the illustrated embodiment, a hanger 112 is arranged radially inward from the housing 106 and includes a shoulder 114 that receives the wellbore sealing system 100. The illustrated hanger 112 may receive one or more wellbore tubulars that are suspended into the borehole 102, for example, to recover hydrocarbons. The wellbore sealing system 100 illustrated in
As described above, the energizing ring 118 is driven into the opening 120 via the setting load, which is a combination of a frictional force between the energizing ring 118 and the seal 116 and an energy to provide compression preload at sealing surfaces 126, 128. In the illustrated embodiment, the energizing ring 118 has a substantially straight edge 130 and a lower tapered portion 132. The substantially straight edge 130 occupies a majority of a length 134 of the energizing ring 118, and as a result, a length 136 of the substantially straight edge 130 may be referred to as a point of interference 138. It should be appreciated that the point of interference 138 may be used to describe a contact area and does not necessarily refer to a singular point or singular location. That is, the point of interference 138 may be used to refer to an extended surface or as an interface between the energizing ring 118 and the seal 116. Because the point of interference 138 is substantially the length 134 of the energizing ring 118, the point of interference may be substantially equal to a total contact area where frictional forces between the energizing ring 118 and the seal 116 may be high. In other words, as the energizing ring 118 is installed, the point of interference is maintained along the length of the energizing ring 118 throughout installation. As a result, a larger force is used to drive the energizing ring 118 into the opening 120. That is, the larger frictional force, along with a pre-determined desired compression preload, leads to a larger setting load. As will be described herein, embodiments of the present disclosure utilize one or more geometric features to reduce the point of interference, thereby reducing frictional forces and reducing the setting load.
As shown, the legs 306, 308 are deformed by the energizing ring 200 such that they move radially outward from the axis 314 of the energizing ring 200. The radially outward force is applied by the peaks 216 that contact the legs 306, 308. In the illustrated embodiment, the valleys 222 are not in contact with the legs 306, 308. As a result, a point of interference 316 at each peak 216 is only formed at the peak or crest and does not include the full lower portion 210 of the energizing ring 200. That is, as the energizing ring 200 is installed within the seal 300, the points of interference 316 formed along a length of the opening 304 may be limited to the areas at the peaks 216. In other words, the varied cross section creates areas of high and low concentrations of pressure alternating axially when installed within the opening of the seal. As a result, a total contact area, which may be equal to the sum of each point of interference 316, is smaller than the contact area of the embodiment illustrated in
As shown, the legs 506, 508 are deformed by the energizing ring 400 such that they move radially outward from the axis 418 of the energizing ring 400. The radially outward force 514 is applied by the peaks 410 that contact the legs 506, 508. In the illustrated embodiment, the valleys 412 are not in contact with the legs 506, 508. As a result, a point of interference 516 at each peak 410 is only formed at the peak or crest and does not include the full lower portion 404 of the energizing ring 400. That is, as the energizing ring 400 is installed within the seal 400, the points of interference 516 formed along a length of the opening 504 may be limited to the areas at the peaks 410. As a result, a total contact area, which may be equal to the sum of each point of interference 516, is smaller than the contact area of the embodiment illustrated in
The foregoing disclosure and description of the disclosed embodiments is illustrative and explanatory of the embodiments of the invention. Various changes in the details of the illustrated embodiments can be made within the scope of the appended claims without departing from the true spirit of the disclosure. The embodiments of the present disclosure should only be limited by the following claims and their legal equivalents.
