Information
-
Patent Grant
-
6182752
-
Patent Number
6,182,752
-
Date Filed
Tuesday, July 14, 199826 years ago
-
Date Issued
Tuesday, February 6, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Duane, Morris & Heckscher LLP
-
CPC
-
US Classifications
Field of Search
US
- 166 7515
- 166 70
- 137 268
-
International Classifications
-
Abstract
A plug-dropping head capable of dropping balls or plugs or other objects is disclosed. The plug-dropping head has a compact design with a cylinder having multiple chambers for storage of plugs and/or balls. The device can be actuated manually or automatically, locally or remotely, to rotate the cylinder to present a different bore in alignment with a flowpath through the housing. An exterior signal indicates that the object has fallen through the device. An indexing feature assures alignment of the individual bores in the cylinder which contain a plug or wiper with the main passage through the tool. Flow can be maintained through the tool as the cylinder is rotated. Rotation of the cylinder allows an obstruction device in the flowpath to move out of the way to allow the ball or plug to drop when sufficient alignment is reached.
Description
FIELD OF THE INVENTION
The field of this invention relates to devices which can be used to drop objects into a wellbore, particularly balls or plugs used during the process of cementing liners.
BACKGROUND OF THE INVENTION
Devices have been used to drop balls or plugs into the wellbore, generally as part of a cementing process for a liner or casing. Balls can be dropped to actuate external packers or liner hangers, while wiper plugs are dropped during the cementing process, with one of the major purposes to wipe the cement from the casing or liner. In this patent application, reference will be made to plug-dropping head with the understanding that different types of objects can be dropped or inserted through it and the reference to plug-dropping head is meant for convenience to be all-inclusive. In situations that required multiple drops of plugs, plug-dropping heads in the past have been stacked vertically, one on top of the other, such that the assemblies could grow to a dimension of nearly 20 ft. or more. Typical of such devices is one made by Nodeco, designated as a top-drive cementing head for dual darts. This assembly is indicated as being approximately 2400 mm long. Other companies have made plug-dropping heads to drop multiple plugs and, in general, all these prior designs have vertically stacked similar or identical assemblies on top of each other so that plugs are arranged one on top of the next and can be dropped sequentially, starting with the lowermost plug. Since these plug-dropping heads are frequently inaccessible to the rig floor, devices have been developed to remotely actuate these plug-dropping heads so that one or more plugs can be dropped when desired. Patents which illustrate the remote actuation of plug-dropping heads are U.S. Pat. Nos. 5,435,390 and 5,590,713. These patents also incorporate the use of vertical stacking of plugs.
The problem with the prior art designs is that the assemblies were overly long, expensive to build, and time-consuming to assemble and effectively operate, primarily due to inaccessibility. What is needed is a compact device which could be simply operated which would also allow for dropping multiple plugs and/or balls. One of the objectives of the present invention is to provide such a compact design which could hold a multiplicity of plugs and/or balls in discrete chambers in a cylinder rotating about a vertical axis. Thus, the objective of a compact design is achieved with the present invention in view of its configuration. Another objective of the present invention is to provide an indexing feature which assures the desired alignment for dropping the plugs. Another objective of the present invention is to signal visually to rig personnel that a plug or ball or other object has been dropped. Yet another object is to allow actuation of the device with ongoing circulation and to configure the device in such a manner that circulation continues as the device is actuated. Yet another object is to construct the device in the manner so as to transmit torque therethrough without stressing threaded connections. Yet another objective is to provide a simple design which is not only compact but also reliable in operation. Those and other objectives of the present invention will become more apparent to those of skill in the art from a review of the preferred embodiment which is described below.
SUMMARY OF THE INVENTION
A plug-dropping head capable of dropping balls or plugs or other objects is disclosed. The plug-dropping head has a compact design with a cylinder having multiple chambers for storage of plugs and/or balls. The device can be actuated manually or automatically, locally or remotely, to rotate the cylinder to present a different bore in alignment with a flowpath through the housing. An exterior signal indicates that the object has fallen through the device. An indexing feature assures alignment of the individual bores in the cylinder which contain a plug or wiper with the main passage through the tool. Flow can be maintained through the tool as the cylinder is rotated. Rotation of the cylinder allows an obstruction device in the flowpath to move out of the way to allow the ball or plug to drop when sufficient alignment is reached.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a sectional elevation of the device showing a ball the instant before it is to drop through the device when the support flapper has rotated out of the way.
FIG. 2
is the view seen along lines
2
—
2
of FIG.
1
.
FIG. 3
is the view along lines
3
—
3
of FIG.
2
.
FIG. 4
is an external elevational view of the apparatus of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The plug-dropping head P is shown in
FIG. 1
to be made of several components. A lower housing
10
has a threaded outlet
12
. Threaded outlet
12
continues as bore
14
. The lower housing
10
has a top surface
16
which accepts the cylinder
18
in a sealing arrangement accomplished by O-ring or any other type of seal
20
. The cylinder
18
has a circumferential ring
22
also seen in FIG.
2
. Circumferential ring
22
has outer teeth
24
which mesh with gear
26
. Gear
26
is connected to crank
27
so that when crank
27
is rotated, the cylinder
18
is rotated with respect to the lower housing
10
and the upper housing
28
. It should be noted that the depicted technique for rotating the cylinder
18
with respect to the housings
10
and
28
is intended to be schematic and to also represent numerous alternative ways of accomplishing the relative rotational movement of the cylinder
18
. For example, cylinder
18
can be moved by a motor powered electrically, pneumatically, or hydraulically, connected to a drive to cylinder
18
. A stepper motor can be used which will accurately rotate the cylinder
18
the precise amount for alignment of the next ball or plug. Those skilled in the art will appreciate other techniques that can be employed to accomplish the rotation of cylinder
18
. While the lower end
30
of cylinder
18
extends into a receptacle
32
in lower housing
10
, the upper end
34
of cylinder
18
extends into a receptacle
36
of upper housing
28
. As previously stated, seal
20
seals adjacent the lower end
30
of cylinder
18
, while seal
38
seals adjacent the upper end
34
of cylinder
18
. Seal
38
is located within receptacle
36
of upper housing
28
.
Upper housing
28
has a threaded inlet
40
which extends into bore
42
, which is in alignment with bore
14
. It can be readily seen that the central axis
44
of the plug-dropping head P is offset from the central axis
46
of the cylinder
18
. This is more clearly seen in
FIG. 2
where the central axes are marked in the plan view.
Referring again to
FIG. 1
, a soft metallic or nonmetallic thrust bearing
48
is installed in the lower housing
10
to facilitate the rotation of the cylinder
18
with respect to the lower housing
10
and upper housing
28
. The thrust bearing
48
can be made of brass or bronze or PTFE or any other compatible material which will facilitate the relative rotation while having sufficient strength to support the weight of the assembly of cylinder
18
.
A cover
50
has a series of slots
52
as shown in FIG.
4
. Tabs
54
extend into slots
52
after the cover
50
has been attached to the lower housing
10
at thread
56
. A bolt
58
holds the tab
54
in slot
52
. The upper housing
28
, as shown in
FIG. 3
, is secured to the cover
50
by nut
60
via threaded connection
62
. Cover
50
has a series of windows
64
through which a lug
66
held by bolt
68
is inserted and fastened. The purpose of lug
66
is to transmit torque from upper housing
28
to cover
50
and to avoid placing applied torque on the threaded connection
62
. Similarly, the tabs
54
act to transfer torque from the cover
50
to the lower housing
10
and avoid placing applied torque on the threaded connection
56
. Those skilled in the art will appreciate that during the cementing procedure, the liner being cemented may be rotated and the string supporting the liner will be connected to the plug-dropping head P through the connections
12
and
40
such that a turning force applied at the rig will be transmitted through the plug-dropping head P in some installations when the liner is being rotated.
As previously stated, the operation of the plug-dropping head P can be automated so that a remote signal can be received at the plug-dropping head P and electronics or other control mechanisms can be actuated to accomplish the turning of the cylinder
18
when desired. A space
70
exists between the cover
50
and the cylinder
18
due to the offset mounting of the cylinder
18
with respect to the axis
44
in which the control mechanisms and/or drive mechanisms can also be installed.
Referring to
FIG. 2
, the cylinder
18
is shown to have bores
72
,
74
,
76
, and
78
. These bores have centerlines which are preferably equidistant from axis
46
. Although four bores are shown, other configurations having greater or fewer numbers of bores in cylinder
18
can be employed without departing from the spirit of the invention. In the plan view of
FIG. 2
, bore
78
is in alignment with bores
14
and
42
. Bore
78
shows clear which can be the position during the pumping of the cement or other fluids. Ultimately, due to the rotation of the cylinder
18
, bores
76
,
74
and
72
, respectively, can come into sufficient alignment with bores
14
and
42
so as to allow a ball or plug therein to drop through bore
14
. Looking at
FIG. 2
, the cylinder
18
rotates in a clockwise direction as shown by arrow
80
. A ratchet
82
, shown schematically in
FIG. 2
, permits only rotation in the direction of arrow
80
without reverse rotation. Those skilled in the art will appreciate that other types of ratcheting devices or their equivalents can ensure unidirectional rotation of the cylinder
18
without departing from the spirit of the invention. Similarly, rotation can be counterclockwise without departing from the spirit of the invention.
Referring again to
FIG. 1
, a plug
84
is secured by threads
86
in bore
88
. In the preferred embodiment, bore
88
, as shown in
FIG. 2
, is located adjacent the bore
78
such that balls or plugs can be loaded into bores
72
,
74
, and
76
in conjunction with clockwise rotation of the cylinder
18
before any of the bores
72
,
74
and
76
are brought into alignment with bores
14
and
42
, respectively, on the lower housing
10
and upper housing
28
. A bleed passage
89
is provided in upper housing
28
such that the threaded connection
86
continues the engagement of plug
84
to upper housing
28
as O-ring or any other type of seal
90
passes above bleed passage
89
to allow pressure to vent out of the plug-dropping head P through passage
88
before the removal of plug
84
. Plug
84
is removed for loading of balls or plugs into the bores such as
72
,
74
and
76
.
Another feature of the present invention is the signaling feature. Referring to
FIG. 3
, a flapper
92
, which acts as an obstruction device, is shown in two positions. Flapper
92
pivots about rod
94
whose end can be seen in FIG.
3
. Rod
94
is shown more clearly in
FIGS. 1 and 2
. Rod
94
extends through lower housing
10
, with seal
96
preventing the escape of pressure in the plug-dropping head P. The lower end
30
of the cylinder
18
has a series of oval-shaped recesses
98
, shown in FIG.
2
. In the preferred embodiment, recesses
98
are oriented 90° from each other to correspond to alignment of bores
72
,
74
,
76
or
78
with bores
14
and
42
. Rod
94
has a cam
100
which normally rides on the bottom surface
102
of cylinder
18
. As any one of the bores illustrated in
FIG. 1
come into alignment with bores
14
and
42
, the oval-shaped opening or recess
98
presents itself adjacent the cam
100
, thus allowing the weight of flapper
92
to initiate 90° rotational motion as tab end
104
rotates into recess
98
, as shown in FIG.
3
. At other times, recess
98
is rotated away from tab end
104
, causing a pivoting of the flapper
92
with rod
94
. Thus, referring to
FIG. 3
, the flapper
92
is shown in the open position where a ball or plug can be dropped and the same flapper
92
′ is also shown in
FIG. 3
in the closed position. The flapper
92
′ remains in the closed position until there is near alignment or complete alignment between a given bore in the cylinder
18
and bores
14
and
42
. Attached to the end of rod
94
is indicating flag
106
which is oriented downwardly toward threaded outlet
12
when the flapper
92
is in the open position shown in FIG.
3
.
FIG. 4
also illustrates the flag
106
indicating to rig personnel that a ball or plug has dropped through bore
14
. The other position of flag
106
is 90° rotated from the position shown in FIG.
4
and indicated as
106
′ in FIG.
4
.
Those skilled in the art will appreciate that although a 90° rotating flapper
92
has been illustrated as the device to selectively retain a ball or plug prior to its being dropped through bore
14
, other devices can be used, and the primary objective of the assembly just described is to give rig personnel a signal that a ball or plug has become aligned with the bore
14
and the ball or plug has been dropped due to removal of a support which would keep the ball or plug from falling through bore
14
. Thus, a 90° rotating plug or a series of fingers could also be used as long as they were structurally sound to prevent the ball or plug from passing therethrough under circulating pump pressure internal to the plug-dropping head P. It should be noted that there is no need for the flapper
92
to close off the passage and, in fact, it is desirable to maintain circulation through the plug-dropping head P, even with the flapper
92
′ in the closed position. Along those lines, to ensure the ability to flow sufficiently, particularly while cylinder
18
rotates, a bore
108
is provided in cylinder
18
along central axis
46
. In the preferred embodiment, the upper housing
28
has a cutaway
110
which allows flow through bore
42
to go in the direction of arrows
112
and
114
to accomplish flow through bore
108
back into bore
14
, while at the same time flow is going straight through from bore
42
through the aligned bore in cylinder
18
into bore
14
. Those skilled in the art will appreciate that the configuration shown in
FIG. 2
will always allow flow through bore
108
of cylinder
18
through the recess
110
and its equivalent recess,
116
in bottom housing
10
. While the recesses have been shown in upper housing
28
and lower housing
10
, they could as easily be located in the cylinder
18
itself. The recesses can be configured for continuous flow through bore
108
or they can be sloped or tapered so that flow through bore
108
only occurs for a short period of time during rotation of cylinder
18
and effectively is significantly reduced or eliminated when a bore in cylinder
18
comes into alignment with bores
42
and
14
.
FIG. 3
also indicates an indexing feature which ensures proper alignment of a given bore in cylinder
18
with bores
14
and
42
. Circumferential ring
22
has a series of holes
118
, one of which is shown in FIG.
2
. Mounted to the lower housing
10
is a spring-loaded indexing pin
120
. In the manual version shown in
FIGS. 2 and 3
, the pin
120
is pulled down before the crank
27
is rotated. Once there has been some angular rotation of cylinder
18
, the pin
120
is released and cranking continues with crank
27
. Ultimately, when the next bore in cylinder
18
is in alignment with bores
14
and
42
, the pin
120
pops into hole
118
to prevent further rotation. Those skilled in the art will appreciate that other indexing devices, including those that are automatically operated, are also within the purview of the invention. Thus, especially if the cylinder
18
is motor-driven, a host of devices can be used to stop motor operation after a predetermined angular displacement of cylinder
18
. This can be accomplished by using, for example, a stepper motor to control the rotation of cylinder
18
. It can also be accomplished by putting targets on cylinder
18
and sensing the passage of such targets upon a predetermined rotation of cylinder
18
. The important thing is that there is a mechanism, be it manual or automatic, to ensure that movement of cylinder
18
stops when a given bore in cylinder
18
comes into sufficient alignment with bores
14
and
42
.
Those skilled in the art will appreciate that the figures are truly schematic in several senses. The illustration of a manual crank
27
is intended to be sufficiently schematic so as to encompass a power-driven cylinder
18
which is either locally controlled or remotely controlled from a location removed from the plug-dropping head P. The mechanism involving rod
94
is also intended to be schematic for alternative systems which retain a plug or ball from falling into bore
14
until there is sufficient alignment with the bore in cylinder
18
. Further, the schematic representation of the assembly involving flag
106
with rod
94
is also intended to broadly illustrate numerous alternative techniques of giving visual, audible or other signals to rig personnel that rotation of cylinder
18
has occurred and the ball or plug has dropped. It should be noted that
FIG. 1
illustrates the presence of a ball
122
(which is normally dropped before plugs) suspended in bore
76
just instantaneously before it drops through bore
14
since the flapper
92
is in the open position. Thus, for example, one application of the plug-dropping head P can be the placement of a ball in bore
76
with a plug in bore
74
and bore
72
such that rotation in the direction of arrow
80
will result in first a ball being dropped and the next two rotations will allow plugs to be dropped. The plugs are not shown in the drawings for clarity, and the design of the plugs themselves is not a part of this invention.
Those skilled in the art will now appreciate that what has been demonstrated is a compact design for a plug-dropping head P which can be operated completely manually or automatically, locally or from a remote location and, in a very compact design, can allow rig personnel to drop one or more balls and/or one or more plugs in a very simple design which will operate reliably.
Also illustrated in
FIG. 2
is a counter-balancing weight
124
. Since the cylinder
18
is mounted off-center from axis
44
and may be rotated during cementing, the counterbalancer
124
counterbalances the offset mounting of the cylinder
18
so that vibration is reduced or eliminated. Those skilled in the art will appreciate that the cylinder
18
is mounted in an offset manner on axis
46
so that its various bores can be rotated into a central position in alignment with longitudinal axis
44
. Other type of delivery systems can be used instead of cylinder
18
with bores thereon. Instead of a cylinder
18
, a ring with internal dividers can be used such that turning the ring on its vertical axis will position the next ball or plug for dropping. A belt with dividers can also be used so that rotating the belt about a vertical axis will position successive balls or plugs for dropping.
The compact design of the plug-dropping head P allows faster rig-up due to its lightweight nature and its compact design. The design is fairly simple and the sealing components, such as seals
90
,
38
,
20
, and
96
can be easily replaced, even by rig personnel, if necessary, at the location. The design incorporates a feature so as not to stress threaded connections
56
and
62
when torques are transmitted through the plug-dropping head P. A signaling system is also incorporated and the number and size of the bores in cylinder
18
can be varied to accommodate a particular application.
The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.
Claims
- 1. A device for inserting at least one object into a wellbore, comprising:a housing having a passage therethrough, said passage connectable to a wellbore for insertion of objects therein; a retention device supported by said housing to hold at least one object to be inserted in the wellbore and to selectively position it in said passage of said housing for insertion into the wellbore; an obstruction device in said passage of said housing which prevents release of an object from said retention device until a predetermined alignment between said passage in said housing and the object in said retention device has been achieved.
- 2. The device of claim 1, wherein:said retention device holds a plurality of objects which can sequentially be sufficiently aligned with said passage in said housing for insertion into the wellbore.
- 3. The device of claim 2, further comprising:an external signal device to give an indication that said retention device has positioned an object therein in sufficient alignment with said passage in said housing so that the object can be inserted into the wellbore.
- 4. The device of claim 2, wherein:said device further comprises a rotatably mounted member configured to separately retain the objects for insertion, such that rotation of said member sequentially brings successive objects in sufficient alignment with said passage in said housing to allow their insertion.
- 5. The device of claim 4, wherein:said member comprises a cylinder with multiple bores; said cylinder is motor-driven.
- 6. The device of claim 5, wherein:said motor is actuated remotely to facilitate insertion of objects when said housing is mounted inaccessible to personnel.
- 7. A device for inserting at least one object into a wellbore, comprising:a housing having a passage therethrough, said passage connectable to a wellbore for insertion of objects therein; a retention device supported by said housing to hold at least one object to be inserted in the wellbore and to selectively position it in said passage of said housing for insertion into the wellbore; said retention device holds a plurality of objects which can sequentially be sufficiently aligned with said passage in said housing for insertion into the wellbore; an obstruction device in said passage of said housing which prevents release of an object from said retention device until a predetermined alignment between said passage in said housing and the object in said retention device has been achieved; said obstruction device rotates so as to no longer obstruct said passage in said housing when said predetermined alignment is reached; said rotation operates an external signal to indicate said predetermined alignment.
- 8. A device for inserting at least one object into a wellbore, comprising:a housing having a passage therethrough, said passage connectable to a wellbore for insertion of objects therein; a retention device supported by said housing to hold at least one object to be inserted in the wellbore and to selectively position it in said passage of said housing for insertion into the wellbore; said retention device holds a plurality of objects which can sequentially be sufficiently aligned with said passage in said housing for insertion into the wellbore; said device further comprises a rotatably mounted member configured to separately retain the objects for insertion, such that rotation of said member sequentially brings successive objects in sufficient alignment with said passage in said housing to allow their insertion; said member comprises a cylinder with multiple bores; said cylinder is mounted with its longitudinal centerline offset from the centerline of said housing and in a sealed relationship thereto; said bores which retain an object are located at a predetermined radius from the centerline of said cylinder.
- 9. The device of claim 8, wherein:said cylinder further comprises at least one flow passage therethrough which is in fluid communication with said passage in said housing at least a portion of the time that said cylinder is rotated.
- 10. The device of claim 8, further comprising:a weight mounted to said housing to offset said off-center mounting of said cylinder with respect to said housing when said housing is rotated.
- 11. The device of claim 10, wherein:said housing comprises an upper and lower housing with said cylinder in between, said upper and lower housings each connected to a cover in a manner which transmits applied torque through said cover without going through a threaded connection holding said cover to said upper or lower housings.
- 12. A device for inserting at least one object into a wellbore, comprising:a housing having a passage therethrough, said passage connectable to a wellbore for insertion of objects therein; a retention device supported by said housing to hold at least one object to be inserted in the wellbore and to selectively position it in said passage of said housing for insertion into the wellbore; said retention device holds a plurality of objects which can sequentially be sufficiently aligned with said passage in said housing for insertion into the wellbore; said device further comprises a rotatably mounted member configured to separately retain the objects for insertion, such that rotation of said member sequentially brings successive objects in sufficient alignment with said passage in said housing to allow their insertion; said member comprises a cylinder with multiple bores; said housing comprises an obstruction device held in an obstruction position by the position of said cylinder relative to said housing, said obstruction device movable out of said passage when rotation of said cylinder has brought a bore thereon into sufficient alignment with said passage to allow the object to be inserted into the wellbore.
- 13. The device of claim 12, wherein:a signaling device on said housing to give a signal that said obstructing device has rotated out of said passage in said housing.
- 14. The device of claim 13, wherein:said rotation of said cylinder beyond said point of sufficient alignment rotates said obstructing device back into said passage until the next bore in said cylinder presents itself in sufficient alignment with said passage in said housing to allow another object to be inserted.
- 15. The device of claim 12, wherein:said obstructing device allows flow through said passage while obstructing said passage sufficiently to prevent an object from passing; said cylinder comprising a flowpath therethrough separate from said bores retaining objects such that flow through said passage in said housing and through said flowpath can occur as said cylinder is rotated.
- 16. The device of claim 14, wherein:said obstruction device comprises a rod-mounted flapper actuated by a cam; said cylinder having a recess associated with each bore thereon so that when said sufficient alignment is reached, said cam can rotate into said recess to move said obstruction device out of said passage in said housing; further rotation of said cylinder forces said cam out of said recess to rotate said obstruction device back into said passage in said housing.
- 17. A device for inserting at least one object into a wellbore, comprising:a housing having a passage therethrough, said passage connectable to a wellbore for insertion of objects therein; a retention device supported by said housing to hold at least one object to be inserted in the wellbore and to selectively position it in said passage of said housing for insertion into the wellbore; said retention device holds a plurality of objects which can sequentially be sufficiently aligned with said passage in said housing for insertion into the wellbore; said device further comprises a rotatably mounted member configured to separately retain the objects for insertion, such that rotation of said member sequentially brings successive objects in sufficient alignment with said passage in said housing to allow their insertion; said member comprises a cylinder with multiple bores; said cylinder is prevented from rotating in one direction; said cylinder can be manually rotated; said housing has an indexing feature which selectively prevents further rotation of said cylinder when a bore therein has achieved sufficient alignment with said passage to allow an object to pass, whereupon said indexing feature can be overridden to allow further cylinder rotation.
- 18. The device of claim 17, wherein:said indexing feature comprises a biased pin on one of said cylinder and said housing which engages a stop on the other of said cylinder and said housing to signal said sufficient alignment.
US Referenced Citations (15)