US20030146219A1

US20030146219A1 - Apparatus

Info

Publication number: US20030146219A1
Application number: US10/275,844
Authority: US
Inventors: Austen Ross
Original assignee: R B ROSS (STEEL FABRICATIONS) Ltd
Current assignee: R B ROSS (STEEL FABRICATIONS) Ltd
Priority date: 2000-05-10
Filing date: 2001-05-10
Publication date: 2003-08-07
Also published as: GB0225994D0; GB2381026B; WO2001086112A3; WO2001086112A2; GB2381026A; AU2001256472A1; GB0011217D0

Abstract

The present invention relates to apparatus this is particularly, but not exclusively, suited for use as a mud bucket in the oil and gas industry. The apparatus includes a seal that seals the mud bucket to a tubular (e.g. a stand of drill pipe). The seal is attached to the mud bucket via a quick release mechanism so that worn-out or damaged seals can be replaced quickly.

Description

The present invention relates to apparatus for fixing seals to containers used to contain fluids draining from pipes. It is particularly suitable for use in the oil and gas industry on containers such as mud buckets, and provides a quick release mechanism for releasably attaching the seal between the mud bucket and lengths of drill pipe.

When drilling for oil or gas it is customary to use a drill string made up from a number of lengths (or stands) of drill pipe connected together end to end. The stands of drill pipe are typically coupled together using screw threads. The drill string is provided with a drill bit on a lower end and the drill bit is typically rotated by pumping drill fluid or mud through the string and a mud motor that imparts a rotational force to the drill bit to create a borehole. The mud can also pass out through the bit so that the drill fluid cools and lubricates the bit during the drilling operation and conveys drill cuttings from the face of the borehole back to surface.

When the borehole has been drilled, the drill string is removed from the borehole and dismantled stand-by-stand as adjacent stands are disconnected from each other and stored, for example, on the platform of a drill rig. As an upper stand is disconnected from a lower one, the drill fluid in the upper stand will drain from it. It is standard procedure to mount a container around a joint between adjacent stands before they are disconnected to contain the mud, which is expensive and toxic. The container is conventionally called a mud bucket.

The mud bucket typically comprises two semi-cylindrical portions that are longitudinally hinged together and can be closed around the joint between adjacent stands of drill pipe. The mud bucket is provided with an aperture at each end through which the stands extend and a seal is located in each aperture so that the stands may move (e.g. axially and rotationally) relative to the mud bucket but no mud can escape. A conduit typically runs from a drainage port on a lower part of the mud bucket to a collection vessel so that the mud can be collected and recycled if required.

The seal in each aperture needs to be periodically replaced, which generally involves dismantling of the mud bucket and thus increases the time taken to dismantle the drill string. The drill string typically needs to be dismantled and removed from the borehole before a production string or casing, liner etc is located in the borehole to facilitate the recovery of hydrocarbons therefrom.

Bolts are typically used to secure the seal to the mud buckets, and as the bolts are liable to clogging, the downtime may be considerable during replacement of the seals.

According to the present invention there is provided apparatus for containing fluid adapted to engage a tubular, the apparatus comprising a container and at least one seal that seals the container to the tubular in a closed configuration, the seal being attached to the container by at least one bolt that engages with at least one threaded socket wherein the apparatus is adapted to allow quick release and attachment of the seal.

In one embodiment, the quick release is effected by providing a minimal number of bolts. Thus, a lesser number of bolts must be removed to release the seal and then replaced to re-attach the seal.

In a second embodiment, the quick release is effected by providing the bolts with a low pitch screw thread. Thus, the bolts require to be turned a lesser number of times to release the seal and then re-attach it.

In a third embodiment, the quick release is effected by providing the sockets either on the container, or by providing the sockets in the seal itself.

Each of the first, second and third embodiments above may be combined into any combination with one another.

The seal can be attached to an annular flange on the container, the annular flange typically extending into a bore of the container at one or both ends thereof.

In an alternative embodiment, the container is provided at each end with a seal cradle. The seal cradle includes two semicircular portions and the seal includes two semicircular portions that are engaged in respective portions of the cradle. Each portion of the cradle includes an annular flange that extends inwardly, and the portions of the seal are typically located under the flange.

The annular flange is typically provided with apertures therethrough to receive the bolt, and the seal is typically fixed against the flange. In one embodiment, the flange has a rib or lip circumscribing an inner periphery of the flange and the rib or lip typically bears against the seal when the seal is attached to the flange. This lip or rib can enhance the quality of the seal, by resisting the passage of fluids past the joint between the flange and the seal.

The socket is typically captive on the seal or the container. For example, the socket may be provided on the flange of the container adjacent an end thereof, and preferably adjacent to an end aperture of the container. In a preferred embodiment, the socket is captive on the seal and is typically embedded therein. The socket can have a grease injection point such as a grease nipple at the opposite end of the socket to the end that receives the bolt.

The container is typically provided as two separate portions. Optionally, the two portions of the container are connected together, typically by a hinge.

The threads in the socket and the threads of the bolt are preferably of shallow pitch, e.g. 1 to 4 turns per inch and preferably around 2 turns per inch. Thus, a typical bolt only has a few turns along the shank. This enables the bolt to be engaged with and released from a respective socket with minimal turning. The threads can optionally be interrupted so that they do not extend around the whole circumference of the shaft of the bolt. This facilitates clearance of cuttings and other debris from the threads, and also substantially prevents corrosive fluids from being retained in the threads.

The seal is typically at a lower end of the container in use Two seals are typically provided, with a seal typically being disposed at opposite ends of the container. A plurality of bolts is preferably provided e g. 2 to 10 bolts per seal. The bolts may be hand-operated. A plurality of threaded sockets are typically provided on the apparatus, preferably a separate threaded socket for each bolt. Thus, a socket is typically provided for each bolt. The sockets may be attached to the container by any suitable means or sockets may be pre-formed therein. The threaded rockets are preferably held in the seal adjacent to apertures in the container.

The apparatus typically includes at least one plate. Typically the apparatus includes two plates for each seal. The sockets may be provided between the two plates.

Typically, each seal comprises two portions that may in preferred embodiments be semicircular in cross-section. Each seal is typically held between the two plates, but the plates may be embedded within the seal.

Each seal is typically attached to the container (e.g. by coupling directly to a flange of the container or by coupling to the seal cradle that is attached to the container) before the seal is connected to the tubular. The bolts are typically driven through an upper plate into the threaded sockets to secure the seal onto the container. Optionally, the bolts may extend into a lower plate.

Typically, the second seal is attached to the other end of the container by the same procedure.

The seal preferably comprise a resilient substance such as a rubber or plastics material.

The seals are typically replaced periodically. This typically entails removing the apparatus from the tubular, unscrewing the bolts from the threaded sockets, removing the worn-out seals and replacing the seal. The apparatus is then typically reassembled and connected to the tubular.

Typically, a first seal seals a connection between an upper stand of tubular (e.g. drill pipe) and the container. A second seal typically seals a connection between a lower stand of tubular (e.g. drill pipe) and the container.

Typically, the respective portions of the seal, plates and container connect to seal the apparatus to the tubular to form a sealed container around the join between two tubulars (e.g. between two stands of drill pipe.

The apparatus typically includes an outlet for draining fluid that collects in the container. The fluid is typically drill fluid or mud and is optionally recycled.

The tubular typically comprises two or more stands of drill pipe that have been coupled together (e.g. by screw threads). After the apparatus has engaged the drill pipe, adjacent stands of pipe are typically disconnected to release fluids into the container. The contained fluids are typically drained through the outlet, and the container is decoupled from the pipe and subsequently the upper pipe is typically completely disconnected from the lower one; the drill string is then raised to locate a further joint between adjacent stands of drill pipe at the level of the container The next stand of pipe may then be removed in a similar fashion. This process may then proceed to remove each stand of pipe in turn while containing the drilling fluids.

Embodiments of the present invention shall now be described, by way of example only, and with reference to the accompanying drawings, in which: [0029]
FIG. 1 is a perspective view of a first embodiment of a mud bucket; [0030]
FIG. 2 is a front cross-sectional view of an alternative embodiment of a mud bucket; [0031]
FIG. 3 is a plan view of a seal cradle for use with the mud bucket of FIG. 3; [0032]
FIG. 4 is a cross-sectional view through the line A-A of the seal cradle of FIG. 3; [0033]
FIG. 5 is a perspective view of part of a seal for use with the mud bucket of FIG. 2; and, [0034]
FIG. 6 is a front (a) and side (b) views of a fixing for use with the FIG. 5 seal. [0035]
Referring now to the drawings, FIG. 1 shows a container or mud bucket [0036] 1 that comprises first and second portions 2 a, 2 b with semicircular cross-sections. The portions 2 a, 2 b are connected by axially spaced-apart hinges 19. The mud bucket 1 is engaged around a joint 15 between two stands 4, 5 of drill pipe and sealed at an interface 3 between the first and second portions 2 a, 2 b of the mud bucket 1. FIG. 2 shows a preferred embodiment of a mud bucket 100 that is substantially the same as mud bucket 1, but has fewer bolt holes that allow the seal 10 to be coupled to the mud bucket 100 easier and quicker as will be described. Like reference numerals have been used in FIG. 2 to designate like parts, prefixed “1”.
Referring in particular to FIG. 1, an [0037] upper seal 10 is provided at an interface between the stand 4 and an upper end of the mud bucket 1. A lower seal 20 is provided at a lower end of the mud bucket 1 and the lower stand 5. The lower seal 20 functions and is constructed in the same manner as the upper seal 10 and will not be described hereafter in detail The seals 10, 20 are typically made from rubber although other resilient materials such as plastics may be used.
A [0038] central aperture 24 extends through the centre of the seal 10 to allow passage of the pipe stands 4, 5 therethrough. Mud or fluids present in the mud bucket 1 cannot escape past the seals 10, 20 although the stands 4, 5 may rotate therein and move axially therethrough.
Referring now to FIGS. 3 and 4 in particular, there is shown a [0039] seal cradle 50 that is adapted to be coupled to each end of the mud bucket 1. A seal cradle 50 is typically located at each end of the mud bucket 1, and each seal cradle 50 includes first and second arcuate portions 52, 54.
The [0040] seal 10, which is typically a resilient member, is located in the cradle 50 and is held in place using two semicircular plates 21, 22 that are axially spaced-apart and coupled together using nuts 13. The plates 21, 22 with the seal 10 are located in one of the portions 52, 54 of the cradle 50. A second set of plates (not shown) that are similar to plates 21, 22 are used in the other of the portions 52, 54.
Each [0041] portion 52, 54 includes a semicircular aperture 56 so that when the portions 52, 54 are brought together in use (as shown in FIG. 3), there is formed a circular aperture through which the stands 4, 5 may pass.
The [0042] seal 10 has two arcuate portions (not shown) that are each semicircular and can fit between the plates 21, 22. An upper and lower race of each portion of the seal 10 can be substantially co-planar with an upper face 22 f of plate 22 and a lower face 211 of plate 21 so that the seal 10 is substantially between the plates 21, 22. However, the seal 10 may take any form and the plates 21, 22 can be embedded in the seal 10, providing that apertures 25 a, 25 b in the plates 22, 21 that allow access to nuts 13 are left accessible. Alternatively, The portions of the seal and the plates 21, 22 join to form half of the seal 10. When the two portions of the seal 10 are brought together, the seal 10 has a circular cross-section in a horizontal direction through FIG. 1 after the mud bucket 1 is engaged with the stands 4, 5 and sealed at interface 3.
The [0043] apertures 25 a, 25 b extend axially through the plates 21, 22 and the nuts 13 are provided between the aperture 25 a in plate 22 and aperture 25 b in plate 21. The nuts 13 are provided with a thread that corresponds with the thread of bolts 12 that are used to couple the seal 10 to the seal cradle 50. One of the portions 52, 54 of the seal cradle 50 is attached to the portion 2 a of the mud bucket and the other of the portions 52, 54 is attached to the other portion 2 b of the mud bucket 1 before the mud bucket 1 is engaged with the stands 4, 5.
An upper surface of [0044] portion 52 of the seal cradle 50 is formed as an inwardly extending flange 27, and an upper surface of the portion 54 of the seal cradle 50 is similarly formed as an inwardly extending flange 28. Two circumferentially spaced-apart apertures 60 are provided in the flange 27, and two circumferentially spaced-apart apertures 62 are provided in flange 28. The apertures 60, 62 allow the bolts 12 to extend therethrough to engage with the nuts 13 of the plates 21, 22. Although a total of four apertures 60, 62 are shown in FIG. 3, the number of apertures 60, 62 and thus the number of bolts 12 that are used to couple the seal 10 to the cradle 50 may be varied. For example, the embodiment shown in FIG. 1 is provided with eight bolts 12 and thus eight nuts 13. The preferred embodiment shown in FIG. 2 is provided with four bolts 12 and nuts 13. The reduction in the number of bolts 12 between the two embodiments reduces the time required to assemble and dismantle the seal 10 and cradle 50, thus making it quicker and easier to replace worn out or damaged seals 10.
To assemble the apparatus, the first portion of the seal [0045] 10 (including the plates 21, 22) is placed under the flange 27 of portion 52 of the cradle 50. Similarly, the second portion of the seal 10 (including the plates 21, 22) is located under the flange 28 of portion 54 of the cradle 50. The bolts 12 are then inserted into the apertures 60, 62 in the flanges 27, 28, through the apertures 25 a in plate 22 and into the nuts 13. The bolts 12 are then driven into the nuts 13 using any conventional means (e.g. a spanner, screwdriver, ratchet etc). The thread on the bolts 12 and the nuts 13 is preferably of a low pitch, i.e. around two turns per inch (approximately two turns per 25 mm). This allows the seal 10 to be attached to the cradle 50 and thus the mud bucket 1 quickly as the bolts 12 require fewer turns than the high pitch threads on conventional bolts 12. The seal 10 is thereby quickly attached to the mud bucket 1. Also, the low pitch threads are not as prone to clogging with mud and cuttings as higher pitch threads because the spaces between the threads is larger and thus less likely to become clogged. The lower pitch of the bolts 12 are also more corrosion resistant as it is less likely that corrosive fluids will be trapped or collect between the threads.
A semicircular lip [0046] 27 l on the flange 27 and a similar lip 28 l on the flange 28 extend inwardly into the bore of the mud bucket 1 and preferably bear against the rubber of the seal 10 when each portion thereof is attached to the flanges 27, 28. The lips 27 l, 28 l create another barrier to the passage of fluids between the seal 10 and the flanges 27, 28 and thereby enhances the seal formed by the seal 10.
In use, the string of drill pipe (eg. stands [0047] 4, 5) is extracted from the borehole once the borehole has been drilled. The portions 2 a, 2 b of the mud bucket 1 are separated and placed around a joint 15 between the upper stand 4 and the lower stand 5 so that the mud bucket 1 seals at the interface 3. The two portions of the upper seal 10 are brought together to form an annular seal around the upper stand 4. The lower seal 20 is formed in the same way and similarly, the two portions of the lower seal 20 are brought together to form an annular seal around the lower stand 5.
The [0048] upper stand 4 is then twisted and released from the lower stand 5 in the conventional manner and moved through but not past the upper seal 10 as shown in FIG. 1, so that mud contained in the upper stand 4 may spill out into the mud bucket 1. Mud contained in the lower stand 5 may also spill into the mud bucket 1. The mud gathers in the mud bucket 1 and may be drained in a controlled manner via a conduit 8 and optionally recycled.
The mud bucket [0049] 1 is then opened via the hinges 19 and the upper stand 4 is completely removed from the assembly and stacked elsewhere. The lower stand 5 is then raised to become the upper stand until its joint with a further lower stand is positioned approximately central in the mud bucket 1. Thereafter, the lower (now upper) stand 5 is disconnected from the stand immediately below it in the string and the remaining mud in stand 5 and some of the mud in the stand below drain into the mud bucket 1. Thereafter, the mud bucket 1 is drained in a controlled manner and the process is repeated until the drill string is removed from the borehole.
The [0050] seals 10, 20 become worn after a period of time and are periodically removed and replaced. To remove the seal 10 for example, the mud bucket 1 is released from the stands of drill pipe via the hinges 19 and disengaged from the stands 4, 5. The bolts 12 are removed to release the two portions of the worn seal 10 from the respective portions 52, 54 of the cradle 50. The removal of the bolts 12 is aided by their low pitched thread that is less liable to mud ingress and so the time taken to remove the bolts is reduced. As the bolts 12 are provided with a low pitch thread, they require fewer turns to be released and thus the seal 10 can be replaced much quicker than conventional seals.
The [0051] bolts 12, best shown in FIG. 2, are advantageously large enough so that the torque required to remove them can be applied by hand. In the event that the bolts 12 cannot be removed by hand, pliers, spanners or other suitable torque tools may be used.
A [0052] new seal 10 is then placed in the cradle 50 and secured as before by screwing the bolts 12 through the apertures 60, 62 in the flanges 27, 28 and through the threaded nuts 13 in the seal 10. The replacement of the seal 10 is also easier and quicker due to the nuts 13 being attached to the seal 10.
In an alternative embodiment, the nuts [0053] 13 can be attached to the mud bucket 1 (e.g. to the flanges 27, 28 or can form part of the cradle 50) The seal 10 may be adequately sealed by using three or four bolts 12 and so the time taken to dismantle the mud bucket 1 and replace the seals 10 is minimised. The lower seal 20 nay be replaced in a similar fashion. The mud bucket 1 may then be connected at a joint between two stands as described above.
FIG. 6 shows an alternative embodiment of [0054] bolts 12 a in which a thread 12 t of the bolts 12 a is interrupted at one or more locations 12 i around the circumference of the shaft of the bolt 12 a. The bolts 12 a can co-operate with the nuts 13 in the same manner as the bolts 12, but are less prone to gathering debris and cuttings in their threads owing to the interruptions 12 i in the thread 12 t.
The [0055] bolts 12 a also have rings 12 r on their heads that allow removal of the bolts 12 a from the nuts 13 with only a screwdriver, bar or the like as the shaft of the screwdriver or the bar etc can be located in the ring 12 r and turned. This obviates the use of other torque tools such as spanners etc, thus reducing the time taken to tighten and slacken the bolts 12 a, which also helps to reduce the time needed to remove and replace the seals 10, 20.
An advantage of certain embodiments of the invention is that the nuts [0056] 13 are pre-formed in the seal 10 thereby reducing the time required to replace the seal 10.
Another advantage of certain embodiments of the invention is that the [0057] bolts 12 have a low pitch thread that provides for easier removal of the seals 10, 20 from the mud bucket 1 as the bolts are less liable to mud ingress and require fewer turns to engage and disengage them from the nuts 13. The bolts 12 may also be operated by hand which makes the replacement of the seals 10, 20 quicker and easier. All of these reduce the downtime whilst the seals 10, 20 are replaced.
Modifications and improvements may be made to the foregoing without departing from the scope of the invention. [0058]

Claims

1. Apparatus for containing fluid adapted to engage a tubular, the apparatus comprising a container and at least one seal that seals the container to the tubular in a closed configuration, the seal being attached to the container by at least one bolt that engages with at least one socket wherein the apparatus is adapted to allow quick release and attachment of the seal.

2. Apparatus according to claim 1, wherein the quick release is effected by providing a minimal number of bolts.

3. Apparatus according to claim 2, wherein two to ten bolts are provided per seal.

4. Apparatus according to any preceding claim, wherein the bolts and/or the sockets have a low pitch screw thread.

5. Apparatus according to claim 4, wherein the threads in the socket and the threads of the bolt have between one and tour turns per inch.

6. Apparatus according to claim 4 or claim 5, wherein the threads of the socket and the threads of the bolt have around 2 turns per inch.

7. Apparatus according to any preceding claim, wherein the threads of the bolt are interrupted so that they do not extend around the whole circumference of a shaft of the bolt.

8. Apparatus according to any preceding claim, wherein the sockets are provided on the container or in the seal.

9. Apparatus according to claim 8, wherein the socket is provided on a flange of the container adjacent an end thereof.

10. Apparatus according to claim 9, wherein the socket is provided adjacent to an end aperture of the container.

11. Apparatus according to claim 8, wherein the socket is captive on the seal and embedded therein.

12. Apparatus according to claim 11, wherein the sockets are embedded in the seal adjacent to apertures in the container.

13. Apparatus according to claim 7, wherein the sockets are pre-formed in the container.

14. Apparatus according to any preceding claim, wherein the container is provided at each end with a seal cradle.

15. Apparatus according to claim 14, wherein the seal cradle includes two semicircular portions and the seal includes two semicircular portions that are engaged in respective portions of the cradle.

16. Apparatus according to claim 15, wherein each portion of the cradle includes an annular flange that extends inwardly, and the portions of the seal are located under the flange.

17. Apparatus according to any preceding claim, wherein the seal is attached to an annular flange provided on the container.

18. Apparatus according to claim 16 or claim 17, wherein the annular flange is provided with apertures therethrough to receive the bolt.

19. Apparatus according to claim 18, wherein the seal is fixed against the flange.

20. Apparatus according to any one of claims 16 to 19, wherein the flange has a rib or lip circumscribing an inner periphery of the flange and the rib or lip bears against the seal when the seal is attached to the flange.

21. Apparatus according to any preceding claim, wherein the seal includes two plates.

22. Apparatus according to claim 21, wherein the sockets are provided between the two plates.

23. Apparatus according to claim 21 or claim 22, wherein the seal is held between the two plates.

24. Apparatus according to claim 21 or claim 22, wherein the plates are embedded within the seal.

25. A seal for a container comprising two spaced-apart plates embedded in a resilient material, the seal including at least, one socket located between the two plates.

26. A seal for a container substantially as hereinbefore described with reference to the accompanying drawings.

27. Apparatus for containing fluid adapted to engage a tubular substantially as hereinbefore described, with reference to the accompanying drawings.