DUAL BEARING ROTATING CONTROL HEAD AND METHOD
An apparatus comprises a first bearing assembly, a second bearing assembly, a housing and a pipe. The first bearing assembly, the second bearing assembly and the housing define an interior space. The pipe extends through the first bearing assembly and the second bearing assembly and through the interior space.
Not applicable.
BACKGROUNDThis disclosure relates generally to the field of wellbore pressure control devices. More specifically, the disclosure relates to pressure control devices that control and diver drilling and wellbore fluids while providing a seal around a tubular component.
Wellbore pressure control devices include devices known as rotating control heads, rotating diverters, rotating blowout preventers (hereinafter rotating control head or “RCH”). Such pressure control devices are configured to enable a string of pipe and/or wellbore drilling or intervention tools to sealingly pass therethrough axially, and further to enable rotation of the pipe while sealing the wellbore hydraulically. When used, for example in wellbore drilling operations, a drill pipe string is passed through a bearing assembly in the RCH. The bearing assembly enables a seal element therein and the pipe to rotate relative to a housing that may be affixed to the top of a casing or other pipe disposed at least partially into the wellbore. The housing is configured to enable hydraulic communication to the interior of the wellbore below the bearing assembly. One non-limiting use for RCHs may be in managed pressure drilling.
When bearings in the bearing assembly fail, expensive and difficult procedures to remove the pipe from the wellbore are conducted while maintaining the wellbore hydraulic seal through the RCH. Also, difficult and expensive pipe removal operations are conducted because seal elements in the bearing assembly fail.
An example wellbore operation in which a rotating control head (RCH) may be used is shown schematically in
Typically, during operations, the wellbore 12 is filled with fluid 11, such a “drilling mud”, a completion brine or other fluid used to drill and/or complete the wellbore 12. The fluid 11 is typically lifted from a pit or tank 26 disposed at the surface. The tank 26 may include a supply of cleaned or conditioned fluid 28. The fluid 28 may be lifted by a pump 24 which discharges the fluid to the top drive 22. Internal rotating seal elements in the top drive 22 enable the fluid 28 to be pumped through the interior of the pipe 14 into the wellbore 12. The top drive 22 may also be used to rotate the pipe 14, such as for axially lengthening (drilling) the wellbore 12.
The wellbore 12 may include a pipe or casing 33 (“surface casing”) set to a relatively limited depth near the surface. An upper end of the surface casing 33 may be coupled to a sealing element called a rotating control head 34. The rotating control head 34 may be coupled to the casing by a flange 34B to a corresponding flange 33A at the upper end of the surface casing 33, although the manner of coupling the rotating control head 34 to the surface casing 33 is not a limitation on the scope of the present disclosure.
The rotating control head 34 seals an annular space 12A between the exterior of the pipe 14 and the interior of the surface casing 33 to prevent uncontrolled release of fluid 11 from the wellbore 12. The rotating control head 34 may include a fluid discharge outlet 34A. The fluid discharge outlet 34A may be disposed below sealing elements (
The example shown in
In an example dual bearing assembly rotating control head according to the present disclosure, and as will be explained further below, two independent bearing assemblies, each having a sealing or stripper element associated therewith, may be assembled to a rotating control head housing in tandem and connected to each other in spaced apart relation by a housing such as a spacer spool. A first bearing assembly may be configured to support most of the operating load of wellbore operations. As the first bearing assembly reaches the end of its operable life, whether by impending failure of the bearing and/or the sealing element, a second bearing assembly may enable continuing wellbore operations to a point where the ordinary sequence of wellbore operations would allow for a bearing assembly to be replaced without unduly interrupting wellbore operations.
In the present example, and as will be further explained below with reference to
The first bearing assembly 118 as well as the second bearing assembly 110 may require additional seals within a bearing pack, sufficiently strong to control the intended maximum operating pressures (e.g., 3000 pounds per square inch static) in the wellbore (12 in
The example first and second bearing assemblies 118, 110 may be stabbed onto a pipe (e.g., the pipe 14 in
A side view of an assembled dual bearing assembly rotating control head 34 according to the present disclosure is shown in
The spacer spool 114 may include one or more ports 114A, terminated with couplings such as flanges or other pressure tight coupling features. The one or more ports 114A may be in fluid communication with an interior space (114B in
The first bearing assembly (118 in
The main rotating control head housing 124 may couple to the wellbore pipe or casing (33 in
The fluid discharge port 34A explained with reference to
Some of the details of the first and second bearing assemblies will now be explained with reference to
Each of the first 118 and second bearing 110 and assemblies may include a respective stripper element 122, 116 to provide sealing engagement to a pipe or pipe string moved longitudinally through each bearing assembly 118, 110, respectively, e.g., the pipe 14 as shown in
The sleeve 110A may include a shoulder 110F on an exterior thereof. The shoulder 110F may be in contact with an upper bearing 110C and a lower bearing 110D each on one side of the shoulder 110F. The upper bearing 110C and the lower bearing 110D may rotatably transfer axial loading from the sleeve 110A to a bearing housing 110E. The bearing housing 110E may be the portion of the second bearing assembly that is coupled to the spacer spool 114. The upper bearing 110C and the lower bearing 110D may each be sealed with respective seals 111 of any type known in the art to seal a rotating shaft passing through a bearing supporting such shaft rotatably in a fixed housing.
The first bearing assembly 118 may be mounted in the main rotating control head housing 124 as explained above, and may have substantially the same components, including a sleeve and stripper element 122 as explained with reference to the second bearing assembly 110.
An additional pressure sensor 127B may be disposed in a chamber therefor located above the upper seal 111. In the event any fluid leaks past the second bearing assembly 110, suck leakage may be detected by an increase in the pressure measured by the additional pressure sensor 127B. By using measurements of pressure from the pressure sensor (127 in
As explained above, by having at least one port (114A in
One or more of such indications based on measured pressure may provide the wellbore operator an indication that the first bearing assembly requires removal and replacement. In some examples, such removal and replacement may be performed at a time during wellbore operations so as to minimize disruption of such operations. One specific example may be during a time in which the entire pipe is removed from the wellbore to change a drill bit. During the time in which wellbore operations continue even with failure of the stripper element 122 in the first bearing assembly 118, the stripper element 116 in the second bearing assembly 110 may prevent fluid from bypassing the rotating control head 34, thus providing the wellbore operator with a possible opportunity to continue wellbore operations uninterrupted until a convenient time is available for bearing assembly replacement. The foregoing continuation of wellbore operations may be based on an estimated remaining lifetime of the second bearing assembly and/or the stripper element associated therewith. Provided that the estimated remaining lifetime is at least or exceeds an expected time until the convenient time, wellbore operations may continue until the convenient time, whereupon the first and/or second bearing assemblies may be replaced.
Having two bearing assemblies as described above with reference to
As previously explained, it may also possible to use the one or more ports (114A in
Another example may be to pump fluid, e.g., lubricant, into the interior of the spacer spool (114B in
A rotating control head that includes two independent and sealed bearing assemblies and sealing elements may provide increased safety in wellbore operations and reduced risk of wellbore fluid leakage and consequent environmental hazard.
In one example, an apparatus comprises a first bearing assembly, a second bearing assembly, a housing and a pipe. The first bearing assembly, the second bearing assembly and the housing define an interior space. The pipe extends through the first bearing assembly and the second bearing assembly and through the interior space.
In another example, a method comprises pressurizing fluid to a predetermined value in an interior space defined by a housing, a first bearing assembly and a second bearing assembly. The method further comprises measuring a pressure of the interior space to determine a leak in at least one of the first bearing assembly and the second bearing assembly when the measured pressure differs from the predetermined by a predetermined amount.
In yet another example, a method comprises pumping lubricant into an interior space of an apparatus defined by at least a first bearing assembly and a second bearing assembly. Each of the first bearing assembly and the second bearing assembly comprises a stripper element. The method further comprises inserting a pipe through the interior space so as to go through the first bearing assembly and the second bearing assembly.
Although the preceding description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein. Rather, it extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
Claims
1. An apparatus comprising:
- a first bearing assembly;
- a second bearing assembly;
- a housing, the first bearing assembly, the second bearing assembly and the housing defining an interior space, and
- a pipe extending through the first bearing assembly and the second bearing assembly and through the interior space.
2. The apparatus of claim 1, wherein the housing comprises at least one port in fluid communication with the interior space.
3. The apparatus of claim 2, further comprising a main pressure sensor in fluid communication with the interior space.
4. The apparatus of claim 2, further comprising a fluid pump in fluid communication with the interior space.
5. The apparatus of claim 4, further comprising a pressure regulator in fluid communication with the interior space.
6. The apparatus of claim 5, wherein the fluid pump moves a lubricant.
7. The apparatus of claim 1, further comprising a first pressure sensor located exteriorly of the interior space functionally adjacent the first bearing assembly.
8. The apparatus of claim 1, further comprising a second pressure sensor exteriorly of the interior space adjacent the second bearing assembly.
9. The apparatus of claim 1, wherein each of the first bearing assembly and the second bearing assembly comprises a stripper element, the pipe to be accommodated by the stripper elements.
10. The apparatus of claim 1, wherein the apparatus comprises a rotating control head.
11. A method comprising:
- pressurizing fluid to a predetermined value in an interior space defined by a housing, a first bearing assembly and a second bearing assembly; and
- measuring a pressure of the interior space to determine a leak in at least one of the first bearing assembly and the second bearing assembly when the measured pressure differs from the predetermined by a predetermined amount.
12. The method of claim 11, further comprising measuring a pressure from a first pressure sensor located exteriorly of the interior space and adjacent the first bearing assembly to determine a leak in the first bearing assembly.
13. The method of claim 11, further comprising measuring a pressure from a second pressure sensor located exteriorly of the interior space and adjacent the second bearing assembly to determine a leak in the second bearing assembly.
14. The method of claim 11, wherein the fluid comprises a lubricant.
15. The method of claim 11, further comprising replacing at least one of the first bearing assembly and the second bearing assembly.
16. A method comprising:
- pumping lubricant into an interior space of an apparatus defined by at least a first bearing assembly and a second bearing assembly, each of the first bearing assembly and the second bearing assembly comprising a stripper element; and
- inserting a pipe through the interior space so as to go through the first bearing assembly and the second bearing assembly.
17. The method of claim 16, further comprising moving the pipe with respect to the interior space so as to lubricate at least one stripper element.
18. The method of claim 17, wherein moving the pipe in a first direction introduces the lubricant to the stripper element associated with the first bearing assembly.
19. The method of claim 17, wherein moving the pipe in a second direction introduces the lubricant to the stripper element associated with the second bearing assembly.
20. The method of claim 17, wherein the pumping generates a pressure substantially equal to a pressure in an annular space in a wellbore.
Type: Application
Filed: Feb 11, 2014
Publication Date: Dec 31, 2015
Inventor: Jason Philip Lock (Red Deer, Alberta)
Application Number: 14/766,576