RING SEALS FOR OIL AND GAS APPLICATIONS

BACKGROUND

1. Field of Invention

[0001]This disclosure is related to sealing within oil and gas wells and specifically to ring seals in oil and gas applications.

2. Description of the Prior Art

[0002]A subsea well or any completion installation may include equipment and infrastructure to support hydrocarbon production and other features associated therewith. Aspects of the subsea well or completion installation may include an assembly of casings, tubing, hangers, valves, seals, and control systems that may reside on or close to at least one well, and may be associated with at least one wellheads. A ring seal as part of the seal aspects may include stainless steel seals. The ring seal may have a low external pressure rating (such as for 1 Kilo pounds per square inch (ksi)). The ring seal may be sensitive to geometric variability (such as tolerance) and misalignments in the system, which may make it challenging when used with certain low pressure operations, subsea wells, or completion installations.

SUMMARY

[0003]In at least one example, a system for a subsea well or completion installation may include a ring seal having a web feature and a lip feature. The system may include at least one groove between the web feature and the lip feature. The at least one groove may include a groove bottom transition which is aligned along a horizontal axis which is perpendicular with respect to a vertical axis of a wellbore of the subsea well or completion installation.

[0004]In at least another example, a method for a subsea well or completion installation may include preparing a ring seal having a web feature and a lip feature. The step of preparing the ring seal may include preparing the ring seal to fit within at least one component of the subsea well or completion installation. The method may include forming at least one groove between the web feature and the lip feature. The step of forming at least one groove may be such that the at least one groove may be formed to include a groove bottom transition which is along a horizontal axis which is perpendicular with respect to a vertical axis of a wellbore of the subsea well or completion installation.

[0005]In yet another example, a method for a subsea well or completion installation may include determining a pressure rating to be associated with a ring seal of the subsea well or completion installation. The method may include a step for determining the ring seal to be used with the subsea well or completion installation, based in part on the pressure rating. The ring seal may include a web feature, at least one lip feature, and at least one groove between the web feature and at least one lip feature. The at least one groove may include a groove bottom transition which is along a horizontal axis which is perpendicular with respect to a vertical axis of a wellbore of the subsea well or completion installation. The method may include installing the ring seal between a wellhead housing or mandrel and a master valve block in the subsea well or completion installation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]Various examples in accordance with the present disclosure will be described with reference to the drawings, in which:

[0007]FIG. 1 illustrates an example system subject to a ring seal having a groove bottom transition which is aligned along a horizontal axis of a wellbore of a subsea well or completion installation, according to at least one example herein.

[0008]FIG. 2 illustrates an application of a ring seal having a groove bottom transition which is aligned along a horizontal axis of a wellbore, according to at least one example herein.

[0009]FIG. 3A illustrates physical details of a ring seal, according to at least one example herein.

[0010]FIG. 3B illustrates details of a symmetry and a fit of a ring seal within an application, according to at least one example herein.

[0011]FIG. 4 illustrates sealing details of a ring seal, according to at least one example herein.

[0012]FIG. 5 illustrates a process flow for an example system or steps, as described with respect to one or more of FIGS. 1-4, in accordance with at least one example.

[0013]FIG. 6 illustrates another process flow for an example system or steps, as described with respect to one or more of FIGS. 1-4, in accordance with at least one example.

DETAILED DESCRIPTION

[0014]In the following description, various examples will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the examples. However, it will also be apparent to one skilled in the art that the examples may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the example being described.

[0015]In at least one example, to address one or more of such issues described throughout herein, a system for a subsea well or completion installation may include a ring seal having a web feature and at least one lip feature. In one example, there may be two lip features on the ring seal. The system may include at least one groove between the web feature and the at least one lip feature. The at least one groove may include a groove bottom transition which is aligned along a horizontal axis which is perpendicular with respect to a vertical axis of a wellbore of the subsea well or completion installation. The ring seal prepared in accordance with such an example may include a high interference fit, on the at lest one lip feature, of a minimum of 0.030 inches in a normal-to-seal band direction. The ring seal may also include the at least one groove that may be annular or circumferential between a top web feature and a top lip feature, as well as a bottom web feature and a bottom lip feature. The arrangement of the top and bottom web and lip features with their respective grooves may be so that there is structural and feature symmetry in the ring seal with respect to a horizontal axis that is perpendicular to the vertical axis of the wellbore. The ring seal with the groove and structural symmetry may include improved flexibility that may be beneficial in high interference fits. For instance, a benefit from improved flexibility may be realized because the structural and feature symmetry may ensure plastic strains are not excessive.

[0016]The ring seal may include a large radius of its radius transition on the lip feature and which may be a minimum of 0.5 inches. The radius transition may be on the lip feature, from an exterior side of the ring seal to an interior side of the ring seal. This may allow the ring seal to have reduced contact stresses during installation, where the contact stresses may be in part due to the high interference fit (of a minimum of 0.03 inch, in one example). In one example, the radius transition may mitigate or reduce the risk of galling or scratching. The ring seal may have at least two angled sealing surfaces of the lip feature. The high interference fit may ensure a tighter and more reliable seal when used in a subsea well or completion installation. To accommodate this tight fit and prevent excessive strain, the seal may include circumferential grooves on both the top and bottom faces of the web features. The grooves may enhance flexibility in the ring seal at least during installation.

[0017]The ring seal may include a large radius transition of about 13 to about 25 degrees. This may reduce contact stresses during installation and may minimize the risk of galling or scratching. The ring seal may include an about 21 degree angled sealing surface that may transition to an 18 degree angled sealing surface. The transition between the angled sealing surfaces may be a smooth or direct transition that may be devoid of any intermediate angles or grooves. The at least two angled sealing surfaces may form its sealing angles with respect to a vertical axis of the wellbore. The angled sealing surfaces may provide enhanced support in high-pressure environments, including up to 15 kilo pounds per square inch (ksi). This also ensures that the ring seal is capable of robust performance under challenging conditions. The angle of the angled sealing surfaces may be between about 1 to 7 degrees less than an angle of its corresponding mating surfaces of the subsea well or completion installation. In one example, the at least two angled sealing surfaces may be formed of individual angles with respect to the vertical axis of the wellbore and may be such that each of the angled sealing surfaces is away from a corresponding mating surface by about 1 to 7 degrees.

[0018]FIG. 1 illustrates an example system subject to a ring seal having a groove bottom transition which is aligned along a horizontal axis which is perpendicular with respect to a vertical axis of a wellbore of the subsea well or completion installation, according to at least one example herein. The system 100 may include a platform 102, which may be a ship or a terrestrial feature. The platform 102 may be a floating or fixed (such as anchored or jack-up) structure associated with a water surface 104 of a water environment. The platform 102 may be a base for subsea well or completion installation and other operations for extracting and processing oil and gas.

[0019]The platform 102 may be associated with a well production or injection tree for controlling the flow of hydrocarbons or other media (such as CO2, produced water) from or to the well. The platform 102 may include valves, chokes, and other equipment for regulating and monitoring the production. Further, the platform 102 may include an Xmas or production tree, a blowout preventer (BOP) stack, a tubing hanger, seals, and other components suitable for the subsea well or completion installation. One or more features have been removed for clarity with the present discussion, but it is readily apparent that removal or inclusion of certain features is not intended to be limited, but provided by way of example only.

[0020]The platform 102 may be substantially above a wellbore 106. A wellbore 106 may extend along a vertical axis 140, which may also be referred to herein as a wellbore axis. A wellhead housing or mandrel 108 may sit at a top of the wellbore 106 and may allow flow therethrough. The wellbore housing or mandrel 108 may be connected to a BOP 110. The BOP 110 may include shear rams 112, sealing rams 114, and/or an annular ram 116. One purpose of the BOP 110 may be to control pressure in the wellbore 106. The BOP 110 may be connected to the platform 102 by a riser 118. With respect to drilling operations, a drill string 120 may be passed from a rig 122 on the platform 102, through the riser 118, through the BOP 110, through the wellbore housing or mandrel 108, and into the wellbore 106.

[0021]A lower end of the drill string 120 may be attached to a drill bit 124 that extends the wellbore 106 as the drill string 120 turns. There may be a mud pump 126 with mud lines 128 connecting the mud pump 126 to the BOP 110. The system 100 may include a mud return line 130 connecting the mud pump 126 to the platform 102. A remotely operated vehicle (ROV) 132 may be used to make adjustments to, repair, or replace equipment as necessary. Although a BOP 110 is illustrated, the wellbore housing or mandrel 108 may be attached to other well equipment as well, including, for example, a tree, a spool, a manifold, or another valve or completion assembly.

[0022]In one example, drilling a wellbore 106 may start through use of a suction pile 134. An operation may be performed to attach the wellbore housing or mandrel 108 to the top of the suction pile 134. The suction pile 134 may be lowered to a sea floor 136, if the system 100 is for subsea well. As interior chambers in the suction pile 134 are evacuated, the suction pile 134 may be driven into the sea floor 136, until the suction pile 134 is substantially submerged in the sea floor 136 and a wellbore housing or mandrel 108 is positioned at the sea floor 136 so that further drilling can commence. As the wellbore 106 is drilled, walls of the wellbore may be reinforced with concrete casings 138 that provide stability to the wellbore 106 and help to control pressure from the formation.

[0023]While FIG. 1 discusses drilling operations, the system 100 may support well production operations and may include a master valve block (MVB 202 in FIG. 2) and other components used for well production. The system 100 may support injection tree operations for controlling injection flow of hydrocarbons or other media into a wellbore 106. A sealing or a sealing connection may be provided between at least two components in the system 100 for drilling, for well production, or for injection tree operations. In one example, the two components may include a tubing head spool on a wellhead, the MVB on a tubing head spool, or a blow-out preventor (BOP) on a wellhead. The sealing may be performed in any operation by, in part, using hydraulic cylinders to force dogs of rings and seals into engagement with one or more of the at least two components. The ring seal may be used in support of such sealing and in support of drilling operations, well production operations, or injection operations.

[0024]FIG. 2 illustrates an application 200 of a ring seal having a groove bottom transition which is aligned along a horizontal axis of a wellbore, according to at least one example herein. The illustration in FIG. 2 is a block representation and is not implied as a literal representation of the application 200. The application 200 may be a subsea tree assembly and may include a wellhead housing or mandrel 108 between a wellbore 106 and a MVB 202. There may be one or more tubulars 210 associated in the application 200. The MVB 202 may have an MVB bore 202A. The MVB 202 may have a connector 204 attached therewith and may include the ring seal 208. The connector 204 may also be associated with or may include a spacer ring 206.

[0025]Once the MVB 202 is installed on a wellhead housing or mandrel 108, the connector 204 may be latched onto the wellhead housing or mandrel 108. The connector 204 may preload a joint between the MVB 202 and the wellhead housing or mandrel 108, which may deform or deflect the ring seal 208. A spacer ring 206 may be provided for controlling a standoff between the MVB 202 and the wellhead housing or mandrel 108, which in turn may control an amount of deflection the ring seal 208 may experience. The spacer ring 206 may also transfer a preload between the MVB 202 and the wellhead housing or mandrel 108. As in the case of FIG. 1, one or more features have been removed for clarity with the present discussion, but it is readily apparent that removal or inclusion of certain features is not intended to be limited, but provided by way of example only.

[0026]Although the application 200 is of a wellhead housing or mandrel 108 between a wellbore 106 and a MVB 202, there may be other application of the ring seal 208. In one example, the ring seal 208 may be provided between any components for sealing within oil and gas wells where a wide range of low to high pressure ratings (such as pressure ratings from 1 ksi to 15 ksi) are to be addressed. The MVB 202 may include tubing heads, a Christmas tree, and other components. The MVB 202 may include an MVB bore 202B that may align with a wellhead housing bore 108C of the wellhead housing or mandrel 108. The ring seal 208 is annular, although FIG. 2 illustrates only an interior side (302 in FIG. 3A) of the ring seal 208.

[0027]FIG. 3A illustrates physical details 300 of a ring seal, according to at least one example herein. The physical details 300 include that a ring seal 208 may have an interior side 302 facing a wellbore 106 and an exterior side 304 facing away from the wellbore 106. The physical details 300 include that a ring seal 208 may have multiple web features 306 and multiple lip features 308 on an exterior side 304 facing away from the wellbore 106. The physical details 300 include that a ring seal 208 may have at least one of the grooves 312 between each set of one of the lip features 308 and one of the web features 306.

[0028]FIG. 3B illustrates details 350 of a symmetry and a fit of a ring seal within an application, according to at least one example herein. FIG. 3B illustrates that at least one of the grooves 312 may include a groove bottom transition 356 which may be along a horizontal axis 354 that is perpendicular to a vertical axis 140 of a wellbore 106 of an application 200 or a system 100, such as a subsea well or completion installation. As used herein, the groove bottom transition 356 is in reference to a shape at a bottom of each groove 312 that includes an upwards or downwards facing apex (detailed further in FIG. 4) in alignment horizontal axis that is perpendicular to a vertical axis 140 of the wellbore.

[0029]FIG. 3B also illustrates that the web features 306 may include a web surfaces 358. The web surfaces 358 may be above or below the web features 306. The web surface 358 may be along a horizontal axis 354 which is perpendicular to the vertical axis 140 of the wellbore 106. The web surfaces 358, along with the entire web features 306, may be adapted for or may provide one or more different features or functions in a system which includes the application 200 in FIG. 2. For instance, the web features 306 may include a hold for the ring seal 208 in place (such as being part of a run) when running the ring seal 208 for a subsea installation in the application 200 in FIG. 2. The web features 306 may provide an alignment by, in part, stopping the ring seal 208 from cocking or tilting in an installed position within the system. The web features 306 may provide an increase in a radial stiffness of the ring seal by a first predetermined threshold, which may be predetermined for the application 200.

[0030]The web features 306 may prevent the lip features 308 from over-rotating with respect to a second predetermined threshold when the ring seal 208 is internally pressurized and based in part on the radial stiffness. The web features 306 may provide prevention of excessive deflection in the ring seal by a third predetermined threshold when the ring seal is externally pressured and based in part on the radial stiffness. The web features 306 may provide resistance to movements of rotation and deflection in the ring seal by one or more predetermined thresholds. The resistance may ensure contact at angled sealing surfaces 360 of the lip feature 308 is maintained within predetermined limits so that a sealing interface of the ring seal is maintained. One or more of the first, second, third, or more or more predetermined thresholds may be predetermined for the application 200. The predetermined limits may also be predetermined for the application 200. The predetermination, as used herein, may be based in part on pressure ratings for one or more components to be used in an application of a system having the ring seal 208.

[0031]The details 350 also illustrate that the ring seal 208 incorporates structural symmetry with respect to the horizontal axis 354. For instance, the lip features 308, the web features 306, and the grooves 312 are symmetrically provided on a top and a bottom of the ring seal 208. In another example, one or more of each of the web features 306 may include a web surface 358 and one or more of each of the lip features 308 may include the angled sealing surfaces 360. Each of the angled sealing surfaces may allow an interference fit 362 (generally referred to as a fit), with respect to at least one component, such as the wellhead housing or mandrel 108, and with respect to a sealing interface 364 formed there with. In one example, the fit 362 may be a minimum of 0.03 inches, between at least one of the angled seal surfaces 360 to at least one component of the subsea well or completion installation (such as the wellhead housing or mandrel 108).

[0032]The details 350 also illustrate that each of the lip features 308 may include a flat horizontal surface 366. The flat horizontal surface 366 may be along a horizontal axis 354 which is perpendicular to the vertical axis 140 of the wellbore 106. The details 350 also illustrate that each of the angled sealing surfaces 360 of each of the web features 306 may have different angles (described further in FIG. 4), relative to the vertical axis of the wellbore. The flat horizontal surface 366 may incorporate a radius transition (as in FIG. 4) to the angled sealing surfaces 360.

[0033]FIG. 4 illustrates sealing details 400 of a ring seal, according to at least one example. The sealing details 400 illustrated that there may be one or more angled sealing surfaces 360 of the lip features 308, such as a first angled sealing surface 360A, which may be a secondary sealing surface, and a second angled sealing surface 360B, which may be a primary sealing surface. The one or more angled sealing surfaces 360A, 360B form different angles, such as a first angle 402 and a second angle 404 relative to the vertical axis 140 of the wellbore 106. An angle transition 406 between the angled sealing surfaces 402, 404 may be a smooth or direct transition that may be devoid of any intermediate angles or grooves.

[0034]The first angle 402 and the second angle 404 may be dependent on angles associated with corresponding mating surfaces 352 on the components used with the ring seal 208, such as the MVB 202 and/or the wellhead housing or mandrel 108. In one example, the first angle 402, of the first angled sealing surfaces 360A, with respect to the vertical axis 140, may be between 1 degrees and 3 degrees less than an angle of its corresponding mating surfaces 352. In one example, the second angle 404, of the second angled sealing surfaces 360B, with respect to the vertical axis 140, may be between 3 degrees and 7 degrees less than the angle of its corresponding mating surfaces 352. The corresponding mating surface 352 may have one or more angles and the difference with respect to the first angle 402 and the second angle 404 may be maintained as described above.

[0035]In another example, FIG. 4 also illustrates that a radius transition 408 may be formed between a flat horizontal surface 366 and the first angled sealing surface 360A of each of the lip features 308. The radius transition 408 may include a large radius of at least 0.5 inch radius. Individual grooves 312 illustrated in FIG. 4 may have individual upward or downward facing apex, with individual ones of the grooves 312, between each of the web features 306 and each of the lip features 308, having a groove bottom transition 356 that may include a bottom dimension 356A. Each of the grooves 312 may include sidewall transitions 356B and may include curves or angles between the groove bottom transition 356 and the sidewall transitions 356B. At least the sidewall transitions 356B may be perpendicular or of other angles (illustrated with the broken and the solid lines), with respect to the vertical axis 140. In one example, the bottom dimension 356A of the groove bottom transition 356 is along the horizontal axis 354. The bottom dimension 356A may be a largest linear dimension, over any of the curves or angles formed, at a bottom of the groove 312. The groove bottom transition 356 may be substantially parallel to the horizontal axis 354 or may have a bottom dimension 356A that is a largest linear dimension and that is substantially along the horizontal axis 354.

[0036]FIG. 5 illustrates a process flow or method 500 for an example system or steps, as described with respect to one or more of FIGS. 1-4, in accordance with at least one example. The method 500 may be used for manufacturing or preparing a ring seal for an application. The method 600 may include a step to prepare 502 a ring seal having a web feature and a lip feature to fit within at least one component of the subsea well or completion installation. At least some aspects, including a general annular shape, may be formed or machined as part of the step to prepare 502 the ring seal.

[0037]The method 500 may include a step to determine 504 an application associated with the ring seal. The method 500 may include, as part of the determination 504 of the application, determining pressure ratings associated with the application. The method 500 may include a step to form 506 at least one groove between the web feature and the lip feature. The at least one groove may include a groove bottom transition which is along a horizontal axis which is perpendicular with respect to a vertical axis of a wellbore of the subsea well or completion installation.

[0038]The method 500 may include a further step or sub-step to form angled sealing surface on the lip feature. The angled sealing surface may be formed with respect to a vertical axis for the ring seal. Individual ones of the angled sealing surfaces may include different angles relative to the vertical axis of the wellbore. The method 500 may include a further step or sub-step in which the ring seal is formed from at least stainless steel and is formed with structural symmetry with respect to a horizontal axis that is perpendicular to the vertical axis of the wellbore.

[0039]FIG. 6 illustrates another process flow for an example system or steps, as described with respect to one or more of FIGS. 1-4, in accordance with at least one example. The method 600 of FIG. 6 may be used with the method 500 of FIG. 5. The method 600 in FIG. 6 may be a method of use of the ring seal in one application. The method 600 may include a step to determine 602 a pressure rating to be associated with a ring seal of the subsea well or completion installation. The pressure rating may be a virtue of the application, as detailed with respect to one or more of FIGS. 1-5. The method 600 may include a step to determine 604 the ring seal to be used with the subsea well or completion installation based in part on the pressure rating. The ring seal to be used may be at least provided in schematic or may be cataloged after being subject to simulated renderings and tests. The ring seal may include a web feature, a lip feature, and at least one groove between the web feature and the lip feature. The at least one groove may include a grove bottom transition along a horizontal axis which is perpendicular with respect to a vertical axis of a wellbore of the subsea well or completion installation. The method 600 may include a step to install 606 the ring seal between a wellhead housing and a master valve block in the subsea well or completion installation.

[0040]The method 500 may include a further step or sub-step to adjust the ring seal to provide angled sealing surfaces on the lip feature. The angled sealing surface may be provided to be along a horizontal axis which is perpendicular to the vertical axis of the wellbore. The method 500 may include a further step or sub-step so that the web feature includes a flat horizontal surface and multiple angled sealing surfaces. The flat horizontal surface may be along a horizontal axis which is perpendicular to the vertical axis of the wellbore. Individual ones of the angled sealing surfaces may include different angles relative to the vertical axis of the wellbore.

[0041]One feature in a step or sub-step of the method 500 may be such that at least two angled sealing surfaces provided form different angles relative to the vertical axis of the wellbore. In one example, a first angle of the first angled sealing surfaces may be between 3 degrees and 7 degrees less than an angle of a corresponding mating surface of at least one of the components in an application of the ring seal. In one example, the second angle of the second angled sealing surfaces may be between 1 degree and 3 degrees less than an angle of its corresponding mating surfaces of the same or another one of the components in the application of the ring seal.

[0042]In another example, along with the angles with respect to the corresponding mating surfaces, different angles of the angled sealing surfaces may be between about 1 and about 25 degrees. One feature in the step or sub-step in the method 500 may be such that the at least two angled sealing surfaces form individual angles with respect to corresponding mating surfaces of the subsea well or completion installation. A further feature in the step or sub-step may be such that the at least two angled sealing surfaces form a first one of the individual angles that may be between 1 degree and 3 degrees less than an angle of a corresponding mating surface of the subsea well or completion installation. Another feature in the step or sub-step may be such that the at least two angled sealing surfaces form a second one of the individual angles that may be between 3 and 7 degrees less than an angle of a corresponding mating surface of a subsea well or completion installation.

[0043]The method 500 may include a further step or sub-step such that the ring seal may be formed from at least stainless steel and such that one or more of the web feature or the lip feature may include a sealing surface with an interference fit, with respect to at least one component of the subsea well or completion installation. In one example, the interference fit may be between 0.040 to 0.045 inches. The method 500 may include a further step or sub-step such that the pressure rating within an application using the ring seal is from 1 ksi to 15 ksi. The method 500 may include a further step or sub-step such that the ring seal includes structural symmetry with respect to a horizontal axis that is perpendicular to the vertical axis of the wellbore.

[0044]The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the disclosure as set forth in the claims. Further, any of the many examples discussed here may be combined by a person of ordinary skill using the present disclosure to understand the effects of such combinations.