Patent Application
20110036589
This invention relates to a wellhead connection between two wellhead housing members. The invention also extends to a method of forming a wellhead connection between two wellhead housing members.
Drilling of oil or gas wells typically involves attaching a drilling stack blow out preventer (BOP) stack to a conductor pipe, surface casing or other wellhead component on a temporary basis. Quick connection and break up of the drilling stack is desirable. Known wellhead connections to surface casings or conductor pipes do not readily accommodate this type of drilling stack attachment, see for example the following exemplary patents—U.S. Pat. No. 4,304,424 to Hanson, U.S. Pat. No. 4,239,266 to Mynhier, U.S. Pat. No. 4,936,382 to Thomas, U.S. Pat. No. 5,299,644 to Ekert, U.S. Pat. No. 5,332,043 to Ferguson, and U.S. Pat. No. 6,834,718 to Webster. There is still a need for a wellhead connection to a conductor pipe, surface casing or other wellhead component which will accommodate a drilling stack and which will also allow for quick makeup and disassembly after drilling.
Flanged drilling spools are often used within a drilling BOP stack, however, considerable time and equipment are needed to connect and disassemble. A wellhead spool adapted for quick makeup and disassembly would be useful for drilling and other wellhead applications.
The present invention provides a pressure-containing wellhead connection, and a method of forming a wellhead connection, which can be quickly and easily connected and disassembled at a wellhead.
In one broad aspect, a method is provided for forming a wellhead connection. The method includes:
i. providing a first housing member and a second housing member, each being adapted to be connected together in seated relationship with the first housing member partly within the second housing member, and forming an annulus between the housing members in an area of overlap, and being adapted to form a seal to a cylindrical inner bore when connected together and so as to provide a top connector and a bottom connector for wellhead equipment located above or below, the first housing member being formed with a circumferential groove in its outer periphery in the area of overlap;
ii. providing a radially expandable and contractable latch ring formed from a plurality of latch ring segments and positioned within the annulus so as to be adjacent the circumferential groove;
iii. maintaining the latch ring in an expanded position out of contact with the circumferential groove with radial actuators extending through the second housing member into contact with latch ring segments;
iv. landing the first housing member in the second housing member and optionally forming a seal to the inner bore;
v. moving the latch ring with the radial actuators into a radially contracted position in contact with the circumferential groove; and
vi. locking the latch ring in the contracted position.
In one embodiment, the wellhead connection includes first and second housing members, each adapted to be connected together in seated relationship with the first housing partly within the second housing and forming an annulus between the housings in an area of overlap. The housings may be adapted to form a seal to a cylindrical inner bore (inner bore seal) when connected together. The housings provide a top connector and a bottom connector for connecting to wellhead equipment to be located above and below. The first housing is formed with a circumferential groove in its outer periphery in the area of overlap. A radially expandable and contractable latch ring is formed from a plurality of latch ring segments, the latch ring being held within the annulus so as to be adjacent the circumferential groove. Radial actuators extend through the second housing into contact with the latch ring segments to move the latch ring segments between a contracted position with the latch ring in contact with the circumferential groove, and an expanded position, with the latch ring out of contact with the circumferential groove. An annular retaining ring may be adapted to be positioned in the annulus in contact with the latch ring to lock the latch ring in the contracted position.
In another embodiment, a wellhead connection is provided which includes a generally cylindrical upper housing member having an upper portion and a lower portion and forming a cylindrical inner bore between the upper and lower portions. The upper portion forms a top connector being adapted to make a pressure-containing connection to wellhead equipment to be located thereabove. The lower portion also forms a sealing surface to form an inner bore seal. A circumferential ring groove is formed in an outer periphery of the upper housing member outside the sealing surface. A generally cylindrical lower housing member is provided with a lower end portion forming a bottom connector to connect to a wellhead member to be located therebelow. The lower end portion is adapted to seat the lower portion of the upper housing member in an area of overlap so as to form a continuous inner bore with the cylindrical inner bore of the upper housing or with an inner bore of the wellhead member. The lower housing member is also adapted to form an annular counterbore above the sealing surface, the counterbore forming an annulus to the outer periphery of the upper housing and being threaded at an upper end. The lower housing also forms threaded radial ports extending to the annulus for alignment with the circumferential ring groove. A radially expandable and contractable latch ring formed in a plurality of latch ring segments is adapted to be positioned in the annulus for radial movement between a contracted position locked in the circumferential ring groove, and an expanded position within the annulus. Each latch ring segment is formed with an outwardly opening locking slot. Each of a plurality of threaded radial bolts is adapted to be threaded into one of the radial ports. Each of the radial bolts has a locking end adapted to be received in locking relationship within the locking slot of a latch segment, whereby threaded movement of the radial bolts expands and contracts the latch ring segments. An annular retaining ring is adapted to be retained in the counterbore to lock the latch ring in the contracted position.
In yet a further embodiment, a wellhead connection is provided which includes a generally cylindrical upper housing member forming a cylindrical inner bore between its upper and lower portions. The upper portion forms a top connector adapted to make a pressure-containing connection to wellhead equipment to be located thereabove. The lower portion forms a sealing surface to form an inner bore seal, and a circumferential ring groove being formed in an outer periphery of the upper housing member outside the sealing surface. A generally cylindrical lower housing member has a lower end portion forming a bottom connector adapted to connect to a wellhead member to be located therebelow. The lower housing member is adapted to seat the lower portion of the upper housing member in an area of overlap so as to form an annulus between the upper and lower housing members in the area of overlap above the sealing surface and so as to form a continuous inner bore with an inner bore of the wellhead member. The lower housing is formed with a plurality of threaded radial ports extending to the annulus for alignment with the circumferential ring groove. A radially expandable and contractable latch ring formed in a plurality of latch ring segments is adapted to be positioned in the annulus for radial movement between a contracted position locked in the circumferential ring groove, and an expanded position within the annulus. Each latch ring segment is formed with an outwardly opening locking slot. Threaded radial bolts are provided, each being adapted to be threaded into one of the radial ports, and each having a locking end adapted to be received in locking relationship within the locking slot of a segment, whereby threaded movement of the radial bolts expands and contracts the latch ring segments. In this manner, after the upper and lower housing members are connected, the latch ring may be locked in the contracted position by tightening the bottom connector, such as a threaded connection, between the lower housing member and the casing head.
A split spool wellhead connection 10 such as used for drilling is illustrated in
In
In the first embodiment of
In a preferred embodiment, the well connection 10 may be used within a drilling BOP stack. The split spool 10, formed with upper and lower housings 22, 18, allows one to quickly break the drilling stack into multiple pieces. Small hand tools (ex. sockets and crescent wrench on ends of radial bolts 30, and turning rods in horizontal apertures 42 in retaining ring 40) are all that is required to makeup and break the connection. The sealing arrangement is set up so that the axial force to energize the inner bore seal 19 located between the housings 18, 22 is small. O-ring seals 41 between the retaining ring 40 and the upper and lower housings 22, 18 may be included, although these seals may not need to be pressure seals. The inner bore seal 19 may take the form of an elastomeric seal, such as an O-ring seal, or may take the form of a metal seal ring. Exemplary metal seals suitable for this application are shown in U.S. Pat. No. 5,059,140 to Szymezak; U.S. Pat. No. 6,561,521 to Janoff et al.; and US Published Patent Application 2009/0266558 published Oct. 29, 2009 to Farquharson et al. The seal 19 may be placed on mating, tapered sealing surfaces 44, 45 of the upper and lower housings 18, 22 as shown in
Retaining ring 40 and latch ring segments 25a function to lock all components together. Other styles of latch rings might be used, for instance the locking slots might be differently shaped such as U-shaped. Similarly, alternate radial actuators for the latch ring might be used instead of the threaded radial bolts. However, the embodiment of
While the invention is illustrated with the upper housing 22 landed within the lower housing 18 and forming a continuous inner bore 24, 21 extending there through, it should be understood that the invention has broader applications. For instance, the housings could be reversed, and one or more of the housing members may function as a closed member such as a cap.
The cylindrical inner bore 24′ of the upper housing 22′ is continuous with the cylindrical inner bore 60 of the casing head 54. The inner bores 60, 24′ of casing head 54 and upper housing 22′ respectively are sealed, with an inner bore seal which is shown in FIGS. 7,8 to be a metal seal ring 62. However, in some applications the inner bore seal may have alternate embodiments, or may be formed as an elastomeric seal such as an O-ring seal between overlapping or tapered sealing surfaces between the upper housing 22′ and the casing head 54.
The metal seal ring 62 shown in
The detail of the metal seal at the inner bore is best shown in
Once the upper housing 22′, lower housing 18′, and casing head 54 are connected together, the retaining ring 40′ is tightened in the annulus A′ between the housings 18′, 22′ to lock the latch ring, and optionally to energize the metal seal ring 62, through a downward force applied to the latch ring 25′ and upper housing 22′.
As with the first embodiment, the upper and lower housings 18′, 22′ may be quickly disassembled. After disassembly, the threaded upper end of the casing head 54 is available for a quick threaded connection to an production wellhead, such as a tubing head, through a threaded connector such as is shown in US published Patent Application 2008/0185156, to Rodgers et al., published Aug. 7, 2008.
In yet a further embodiment, the wellhead connection may be formed similarly to that shown in
In still further embodiments, the wellhead connection may be configured similar to the embodiments shown in
As used herein and in the claims, the word “comprising” is used in its non limiting sense to mean that items following the word in the sentence are included and that items not specifically mentioned are not excluded. The use of the indefinite article “a” in the claims before an element means that one of the elements is specified, but does not specifically exclude others of the elements being present, unless the context clearly requires that there be one and only one of the elements. For example, the term “a seal” as used herein and in the claims may include multiple seals.
All references mentioned in this specification are indicative of the level of skill in the art of this invention. All references are herein incorporated by reference in their entirety to the same extent as if each reference was specifically and individually indicated to be incorporated by reference. However, if any inconsistency arises between a cited reference and the present disclosure, the present disclosure takes precedence. Some references provided herein are incorporated by reference herein to provide details concerning the state of the art prior to the filing of this application, other references may be cited to provide additional or alternative device elements, additional or alternative materials, additional or alternative methods of analysis or application of the invention.
The terms and expressions used are, unless otherwise defined herein, used as terms of description and not limitation. There is no intention, in using such terms and expressions, of excluding equivalents of the features illustrated and described, it being recognized that the scope of the invention is defined and limited only by the claims which follow. Although the description herein contains many specifics, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the embodiments of the invention.
One of ordinary skill in the art will appreciate that elements and materials other than those specifically exemplified can be employed in the practice of the invention without resort to undue experimentation. All art-known functional equivalents, of any such elements and materials are intended to be included in this invention. The invention illustratively described herein suitably may be practiced in the absence of any element or elements, limitation or limitations which is not specifically disclosed herein.
This application claims priority from U.S. Provisional Patent Application No. 61/234,570 filed Aug. 17, 2009, which is incorporated by reference in its entirety herein to the extent that there is no inconsistency with the present disclosure.
| Number | Date | Country | |
|---|---|---|---|
| 61234570 | Aug 2009 | US |
