Pressure Control Devices for Sealing Around Tubular Members
A pressure control device for sealing about a tubular string comprises: a flange disposed about a central axis, an annular extension extending from the flange and an annular seal element coupled to the annular extension. The seal member includes a through-passage for receiving the tubular string and an annular recess in which the annular extension is disposed. The annular extension includes a radially-inward facing surface that includes a tapered region that is nonlinear in an axial cross-section for reducing mechanical stresses in the seal member.
Latest National Oilwell Varco, L.P. Patents:
This application claims benefit of U.S. provisional application Ser. No. 62/622,428 filed Jan. 26, 2018, and entitled “Pressure Control Devices for Sealing Around Tubular Members,” which is hereby incorporated herein by reference in its entirety for all purposes.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot applicable.
BACKGROUND Field of the DisclosureThe present disclosure relates generally to drilling systems and to rotating control devices (RCD) for such systems. More particularly, the disclosure relates to systems and methods for providing annular seals between concentric fluid conduits as they rotate relative to each other and as one of the fluid conduits moves axially through the RCD.
Background to the DisclosureIn applications requiring the transmission of fluid under relatively high pressure, it is sometimes necessary to interconnect a rotatable conduit with a stationary conduit, and to provide seals therebetween to prevent leakage of the pressurized fluid. One such application is in drilling operations where a drill pipe or another tubular member passes through a rotating control device (RCD), where the outer housing of the RCD remains stationary while an internal sleeve and packing elements, which are seals, surround and rotate along with the drill pipe. In this arrangement the sleeve and the drill pipe are rotatable conduits. Each packing element includes a rigid annular insert having a mounting flange and a resilient annular seal element that surrounds and contacts the pipe. The packing elements allow the drill pipe to move axially into or out from a wellbore without fluid leakage.
During operation, axial movement of the drill pipe through the RCD causes the resilient the seal elements to deform, expanding and contracting in response to varying outside diameter of the drill pipe and its joints. Such deformation induces life-reducing and thus undesirable mechanical stress in the seal elements.
When it is believed that a seal failure may have occurred, drilling operations are typically halted so that the seals can be inspected and possibly replaced. However, drilling costs are very high, such that downtime must be avoided or minimized as much as possible. Consequently, systems and apparatus that extend the life of the packing elements would be welcomed by the industry.
BRIEF SUMMARY OF THE DISCLOSUREThese and other needs in the art are addressed by a pressure control device having components configured to work together to minimize damaging mechanical stresses and thereby to extend the life of seals and decrease the likelihood that drilling operations must be shut down in order to replace seals. In one embodiment, a pressure control device for sealing about a tubular string comprises: a flange disposed about a central axis, an annular extension extending from the flange and having a radially-inward facing surface; and an annular seal element coupled to the annular extension. The seal member includes a through-passage for receiving the tubular string and an annular recess in which the annular extension is disposed. The radially-inward facing surface comprises a tapered region that is nonlinear in an axial cross-section.
In some embodiments, the radially-inward facing surface flares outwardly, away from the through-passage. The radially-inward facing surface may, in some embodiments, include first and second ends wherein the second end is further from the central axis than the first end. In some embodiments, the radially-inward facing surface comprises a first region extending from the first end and a second region extending from the first region, and wherein the second region is continuously curved in an axial cross-section. The second region may include a constant radius in an axial cross-section. Further, in some embodiments, the radially-inward facing surface comprises a first region extending from the first end and a second region extending from the first region, and wherein the second region, in an axial cross-section, has a radius that has a value selected from the range 0 to 30 inches.
In some embodiments the annular seal element comprises: a seal first end adjacent the flange; a seal second end axially spaced apart from the flange; and a radially outermost surface having first and second regions, wherein the first region extends from the seal first end and the second region extends from the seal second end toward the seal first end and is frustoconical.
Also disclosed herein is a pressure control device for sealing about a tubular string, comprising: a central axis; an annular insert; and an annular seal element coupled to the annular insert. The seal element comprises: a seal first end disposed adjacent the annular insert; a seal second end axially spaced apart from the annular insert; a through-passage extending through the seal first and second ends for receiving the tubular string; and a radially outermost surface including a first region extending from the seal first end and a second region extending from the seal second end toward the first region, wherein the second region tapers as it extends in a direction away from the annular insert. In some embodiments, the second region on the annular seal element intersects the first region, and in some embodiments, the second region is frustoconical. In some embodiments, the annular insert comprises an annular flange disposed about the central axis; an annular extension extending from the flange; and a radially-inward facing surface extending along the annular extension, wherein the annular seal element includes an annular recess in which the annular extension is disposed, the annular recess extending from the seal first end. The radially-inward facing surface of the annular insert includes a tapered region that expands radially outwardly as it extends axially away from the flange. The radially-inward facing surface may, in some embodiments, further include a generally cylindrical region extending from the flange to the tapered region.
Another pressure control device for sealing about a tubular string is disclosed and comprises: a central axis; an annular insert, and an annular seal element. The insert includes a flange disposed about the central axis, an annular extension concentric with the flange and extending from the flange, and a radially-inward facing surface extending along the annular extension. The annular seal element is coupled to the annular extension. The seal element includes: a seal first end disposed adjacent the flange; a seal second end axially spaced apart from the flange; a through-passage extending through the seal first and second ends for receiving the tubular string; and an annular recess in which the annular extension is disposed. The seal element further includes a radially outermost surface having a first region extending from the seal first end and a second region extending from the seal second end toward the first region. The radially-inward facing surface of the annular insert includes a tapered region that expands radially outwardly as it extends axially away from the flange.
In some embodiments, the second region on the annular seal element intersects the first region and in some embodiments, the tapered region is continuously curved. The tapered region of the annular insert may have a constant radius as viewed in a profile on an axial plane.
In some embodiments, the radially-inward facing surface of the annular insert comprises: a first end coupled to the flange, a second end spaced from the first end; and a cylindrical region extending from the first end; wherein the tapered region extends from the cylindrical region toward the second end. In some embodiments, the tapered region of the radially-inward facing surface intersects the second end at a fillet; and wherein the tapered region intersects the fillet at a tangent line that is disposed at angle between 5 and 45 degrees, inclusive, with respect to the central axis.
Thus, embodiments described herein include a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The various features and characteristics described above, as well as others, will be readily apparent to those of ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings.
For a detailed description of the disclosed exemplary embodiments, reference will now be made to the accompanying drawings:
The following description is exemplary of certain embodiments of the disclosure. One of ordinary skill in the art will understand that the following description has broad application, and the discussion of any embodiment is meant to be exemplary of that embodiment, and is not intended to suggest in any way that the scope of the disclosure, including the claims, is limited to that embodiment.
The figures are not drawn to-scale. Certain features and components disclosed herein may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. In some of the figures, in order to improve clarity and conciseness, one or more components or aspects of a component may be omitted or may not have reference numerals identifying the features or components. In addition, within the specification, including the drawings, like or identical reference numerals may be used to identify common or similar elements.
As used herein, including in the claims, the terms “including” and “comprising,” as well as derivations of these, are used in an open-ended fashion, and thus are to be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” means either an indirect or direct connection. Thus, if a first component couples or is coupled to a second component, the connection between the components may be through a direct engagement of the two components, or through an indirect connection that is accomplished via other intermediate components, devices and/or connections. The recitation “based on” means “based at least in part on.” Therefore, if X is based on Y, then X may be based on Y and on any number of other factors. The word “or” is used in an inclusive manner. For example, “A or B” means any of the following: “A” alone, “B” alone, or both “A” and “B.”
In addition, the terms “axial” and “axially” generally mean along or parallel to a given axis, while the terms “radial” and “radially” generally mean perpendicular to the axis. For instance, an axial distance refers to a distance measured along or parallel to a given axis, and a radial distance means a distance measured perpendicular to the axis. Furthermore, any reference to a relative direction or relative position is made for purpose of clarity, with examples including “top,” “bottom,” “up,” “upper,” “upward,” “down,” “lower,” “clockwise,” “left,” “leftward,” “right,” and “right-hand.” For example, a relative direction or a relative position of an object or feature may pertain to the orientation as shown in a figure or as described. If the object or feature were viewed from another orientation or were implemented in another orientation, it may then be helpful to describe the direction or position using an alternate term.
DETAILED DESCRIPTION OF THE DISCLOSED EXEMPLARY EMBODIMENTSThe present disclosure involves sealing between a rotatable conduit and a stationary conduit to prevent fluid leakage. The sealing is achieved by a packing element(s), which serves as a pressure control device and may rotate with the rotatable conduit or may remain stationary with the stationary conduit. Each packing element includes an annular insert having a mounting flange and an annular seal element that surrounds and contacts the pipe. Axial movement of a drill pipe or another tubular string through the packing element may cause the annular seal element, which includes a resilient portion, to deform as it expands and contracts in response to varying outside diameter of the tubular string and its joints. Deformation causes stress in the resilient portion. The packing element embodiments disclosed herein are configured to reduce stress within the seal element as a drill pipe or another tubular string slides into or through the packing element or remains sealingly coupled within the packing element.
Referring to
Housing 110 includes a housing wall or tubular body 111 extending along the central axis 101 from a lower end 112 to an upper end 113, having an outer surface and a through-bore 114. Through-bore 114 is centered on axis 101 and defines an inner wall.
RSA 125 extends at least partially within the through-bore 114 of housing 110. RSA 125 includes a rotatable sleeve 130 received within a bearing assembly 180 to rotate about axis 101 relative to the housing 110, a speed indicator 131 received in sleeve 130 at a location along axis 101 that is aligned with sensor 120 of outer housing 110. Sleeve 130 and pipe 102, when installed, are configured as a rotatable conduit, and housing 110 is configured as a stationary conduit. Sensor 120 is configured to detect the periodic presence of speed indicator 131 as sleeve assembly 125 rotates relative to housing 110 and sensor 120.
In
Rotating sleeve 130 includes a sleeve outer surface 134 and a bore 136 extending from a lower end 132 to an upper end 133. In
Upper sleeve member 140 includes a threaded lower end 142 attached to sleeve coupling 165 and an upper end 133 attached to collar 168. Sleeve member 140 includes a radially protruding annular shoulder 146 located between ends 142, 133 and a port 148 extending into shoulder 146 along a central axis 149 coplanar with central axis 117 of port 116. Some misalignment between axis 149 and 117 is acceptable in various embodiments depending on the sensitivity of sensor 120. Port 148 is configured to receive speed indicator 131 at a fixed position along port axis 149, disposing speed indicator 131 at a fixed distance from axis 101, being generally flush or adjacent to outer surface 134. Whenever sleeve 130 rotates the indicator 131 to the circumferential position of sensor 120, the magnet of indicator 131 is at a fixed distance from sensor 120 within its detection range (e.g. a prescribed distance). Repeated movement of speed indicator 131 past sensor 120 provides a measurement of the rotational speed of sleeve 430 with respect to housing 110. Thus sensor 120 is configured as a speed sensor.
Referring again to
Continuing to reference
Considering surface 230 in
Referring again to
Outermost surface 212 includes a first region 272 extending axially from the seal first end 262 at a taper angle 273 with respect to axis 202 and a second region 274 extending from the seal second end 264 toward the first region 272. In
Annular seal element 305 extends from a seal first end 362 coupled to annular extension 226, adjacent flange 206 to a seal second end 364 axially spaced apart from flange 206. Seal element 305 further includes a through-passage 266 extending through the seal first and second ends 362, 364, an annular recess 268 extending from seal first end 362, and a radially outermost surface 312 extending from first end 362 to second end 364, and having a plurality of axial slots 214, in surface 312. Each axial slot 214 is aligned with a fastener hole 208 in flange 206. Only one pair of aligned slot 214 and hole 208 is shown in
Outermost surface 312 includes a first region 372 extending from the seal first end 362 at a mild taper with respect to axis 302, a tapered second region 374 extending from the first region 372, and a cylindrical, third region 376 extending from the second region 374 to the seal second end 364. Second region 374 and third region 376 intersect at an obtuse angle 377. In
Annular insert 404 includes a first end 422, a second end 424 spaced apart from first end 422 along axis 402, a flange 206 disposed about axis 402 at end 422, an annular extension 426 concentric with flange 206 extending from the flange 206 to end 424, and a cylindrical radially-inward facing surface 430 extending along flange 206 and annular extension 426, and a plurality of axially extending fastener holes 208. The profile view of
Annular seal element 205 is the same as previously described with respect to
Some embodiments of packing elements in accordance with principles described herein include an annular seal element having an outer surface region defined by a single axially-extending character, such as being entirely frustoconical or entirely cylindrical, as examples. Some of these embodiments include slots 214.
While exemplary embodiments have been shown and described, modifications thereof can be made by one of ordinary skill in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations, combinations, and modifications of the systems, apparatuses, and processes described herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. The inclusion of any particular method step or operation within the written description or a figure does not necessarily mean that the particular step or operation is necessary to the method. The steps or operations of a method listed in the specification or the claims may be performed in any feasible order, except for those particular steps or operations, if any, for which a sequence is expressly stated. In some implementations two or more of the method steps or operations may be performed in parallel, rather than serially.
Claims
1. A pressure control device for sealing about a tubular string, comprising:
- a flange disposed about a central axis, the central axis disposed on an axial plane;
- an annular extension extending from the flange and having a radially-inward facing surface; and
- an annular seal element coupled to the annular extension, the seal member having a through-passage for receiving the tubular string and an annular recess in which the annular extension is disposed;
- wherein the radially-inward facing surface comprises a tapered region that is nonlinear in an axial cross-section formed on the axial plane.
2. The pressure control device of claim 1 wherein the radially-inward facing surface flares outwardly, away from the through-passage as the radially-inward facing surface extends axially from flange.
3. The pressure control device of claim 1 wherein the radially-inward facing surface includes a first end extending from the flange and a second end spaced from the first end, and wherein the second end is further from the central axis than the first end.
4. The pressure control device of claim 3 wherein the radially-inward facing surface comprises a first region extending from the first end and a second region extending from the first region, and wherein the second region is continuously curved in an axial cross-section formed on the axial plane.
5. The pressure control device of claim 4 wherein the second region has a constant radius in an axial cross-section formed on the axial plane.
6. The pressure control device of claim 3 radially-inward facing surface comprises a first region extending from the first end and a second region extending from the first region, and wherein the second region, in the axial cross-section, has a radius that has a value selected from the range 0 to 30 inches.
7. The pressure control device of claim 1 wherein the annular seal element comprises:
- a seal first end adjacent the flange;
- a seal second end axially spaced apart from the flange; and
- a radially outermost surface having first and second regions;
- wherein the first region extends from the seal first end; and
- wherein the second region extends from the seal second end toward the seal first end and is frustoconical.
8. The pressure control device of claim 8 wherein on the radially outermost surface, the second region intersects the first region.
9. The pressure control device of claim 1 wherein the radially-inward facing surface lacks a radially inward annular protrusion.
10. A pressure control device for sealing about a tubular string, comprising:
- a central axis;
- an annular insert; and
- an annular seal element coupled to the annular insert, the annular seal element comprising: a seal first end disposed adjacent the annular insert; a seal second end axially spaced apart from the annular insert; a through-passage extending through the seal first and second ends for receiving the tubular string; and a radially outermost surface including a first region extending from the seal first end and a second region extending from the seal second end toward the first region;
- wherein the second region tapers as it extends in a direction away from the annular insert.
11. The pressure control device of claim 10 wherein second region on the annular seal element intersects the first region.
12. The pressure control device of claim 10 wherein the second region on the annular seal element is frustoconical.
13. The pressure control device of claim 10 wherein the annular insert comprises:
- an annular flange disposed about the central axis;
- an annular extension extending from the flange; and
- a radially-inward facing surface extending along the annular extension;
- wherein the annular seal element includes an annular recess in which the annular extension is disposed, annular recess extending from the seal first end; and
- wherein radially-inward facing surface of the annular insert includes a tapered region that expands radially outwardly as it extends axially away from the flange.
14. The pressure control device of claim 13 wherein the radially-inward facing surface further comprises a cylindrical region extending from the flange to the tapered region.
15. A pressure control device for sealing about a tubular string, comprising:
- a central axis disposed on an axial plane;
- an annular insert comprising: a flange disposed about the central axis; an annular extension concentric with the flange and extending from the flange; and a radially-inward facing surface extending along the annular extension; and
- an annular seal element coupled to the annular extension, the annular seal element comprising: a seal first end disposed adjacent the flange; a seal second end axially spaced apart from the flange; a through-passage extending through the seal first and second ends for receiving the tubular string; an annular recess in which the annular extension is disposed, the annular recess extending from the seal first end; and a radially outermost surface including a first region extending from the seal first end and a second region extending from the seal second end toward the first region;
- wherein the radially-inward facing surface of the annular insert includes a tapered region that expands radially outwardly as it extends axially away from the flange.
16. The pressure control device of claim 15 wherein the second region on the annular seal element intersects the first region.
17. The pressure control device of claim 15 wherein the tapered region is continuously curved on the axial plane.
18. The pressure control device of claim 17 wherein the tapered region of the annular insert has a constant radius on the axial plane.
19. The pressure control device of claim 15 wherein the radially-inward facing surface of the annular insert comprises:
- a first end coupled to the flange,
- a second end spaced from the first end; and
- a cylindrical region extending from the first end;
- wherein the tapered region extends from the cylindrical region toward the second end.
20. The pressure control device of claim 19 wherein the tapered region of the radially-inward facing surface intersects the second end at a fillet; and
- wherein on the axial plane, the tapered region intersects the fillet at a tangent line that is disposed at angle between 5 and 45 degrees, inclusive, with respect to the central axis.
Type: Application
Filed: Jan 25, 2019
Publication Date: Aug 1, 2019
Applicant: National Oilwell Varco, L.P. (Houston, TX)
Inventors: Christopher Dale Johnson (Houston, TX), Ajay V. Kulkarni (Sugar Land, TX), Ali A. Al-Quraishi (Katy, TX)
Application Number: 16/257,231