Patent Grant
7086461
The present invention relates to a method and apparatus for gripping tubulars, for example drill pipe. More particularly, the present invention relates to the provision in such a method and apparatus of a mechanism for avoiding the accidental release of tubulars during a handling operation.
During the construction and maintenance of oil wells it is necessary to construct extremely long strings of tubulars. For example, in order to drill a well a drill string is used, whilst after a well has been drilled a casing string must be constructed in order to line the well. Subsequently, a tubing for conveying oil to the surface is inserted inside the casing. Due to the great weight of such tubular strings, possibly several hundred tons, extreme care is required when constructing, raising, and lowering the strings.
A typical sequence of events during the making up of a string is as follows:
The basic construction of the spider 2 and the elevator 5 is the same and is illustrated in a cross-section in
The hydraulic or pneumatic power which can be applied to the pistons which move the slips is limited. The resulting force is not sufficient to raise the slips of an elevator or spider when that elevator or spider is taking the weight of any significant length of tubular. In theory at least it is not possible for an operator to release the slips of the elevator and the spider at the same time, an action which would result in the dropping of the tubular into the well.
A potential problem with the slip design described however is that it is possible, when the new length of casing has been attached to the string and the elevator regrips the tubular, for the elevator to grip the tubular at too high a point such that the slips contact the tubular at the junction between the outstanding box and the main body of the tubular. Thus, the only contact between the slips and the tubular may be over a small part of the length of the slips. This situation is illustrated in
A possible solution to the problem has been disclosed in U.S. Pat. No. 4,676,312. This document describes an interlock circuit in which the supply of pressurised air to the valve which controls the movement of the spider slips is prevented by an interlock valve if the elevator slips are not correctly engaged with the tubing.
According to a first aspect of the present invention there is provided apparatus for gripping and releasing a tubular, the apparatus comprising:
As used here, the term “elevator” means apparatus which is arranged to grip and hold a tubular for the purpose of raising and lowering the tubular. The term “spider” means an apparatus arranged to grip and hold a tubular whilst remaining substantially stationary.
Embodiments of the present invention may significantly reduce the risk of a tubular being dropped into the well as a result of the elevator slips not properly engaging the uppermost length of a tubing string. The movement of the valve controlling the opening of the spider slips is mechanically inhibited if the elevator slips are not correctly engaging the tubular.
Preferably, said valve for directly controlling the supply of pressurised fluid to move the spider slips is a mechanically operated valve which is operated manually. Alternatively however, the valve may be operated by an electrical motor, solenoid, etc, and/or may be remote controlled (e.g. using radio, infra-red, or ultrasonic signals).
In certain embodiments of the present invention, the valve for controlling the supply of pressurised fluid to the spider slips is operated by a lever. The means for mechanically inhibiting movement of the valve comprises a guide plate through which the lever projects. The guide plate is moveable between first and second positions. In a first position the guide plate prevents movement of the lever to open the valve and in a second position allows movement of the lever to open the valve. Movement of the guide from the first position to the second position is prevented if the elevator slips are not correctly closed.
In certain embodiments of the present invention, the apparatus comprises sensor means for detecting when the elevator slips are in the correct gripping position. The sensor means is coupled to said means for mechanically inhibiting movement of the spider control valve.
In certain embodiments of the invention, the sensor means comprises a piston and cylinder arrangement coupled between the main body and the slips of the elevator. The piston and cylinder arrangement is coupled hydraulically to said means for mechanically inhibiting movement of the spider control valve.
In other embodiments of the present invention, said sensor means comprises a switch which is moved from a first position to a second position when the elevator slips are moved to the correct closed position. When the switch is in the first position, movement of the guide plate from its first to its second position is prevented. When the switch is in the second position, movement of the guide plate from its first to its second position is possible. More preferably, the switch controls the supply of pressurised fluid to a piston and cylinder arrangement, the piston of which locks the guide plate in its first position when the supply of pressurised fluid to the cylinder is prevented, and releases the guide plate when the supply of pressurised fluid to the cylinder is allowed. Preferably, said switch is arranged to directly open and close a hydraulic or pneumatic circuit. Alternatively, the switch may form part of an electrical circuit which is arranged to open and close a hydraulic or pneumatic circuit.
The means for mechanically inhibiting movement of the spider control valve may comprise a piston and cylinder arrangement of a hydraulic or pneumatic circuit coupling an elevator control valve to a piston and cylinder arrangement for opening and closing the elevator slips. The first mentioned piston and cylinder arrangement is located between the piston and cylinder arrangement for moving the slips and the elevator control valve. A rod of the first mentioned piston and cylinder arrangement is displaced by the flow of fluid in the circuit to inhibit or allow movement of the spider control valve.
Other arrangements for locking and unlocking the guide plate are envisaged. The sensor may be an optical or electrical switch which detects closure of the elevator slips. The switch may control the supply of pressurised fluid (pneumatic or hydraulic) to a guide plate locking means.
The apparatus may comprise a mechanical link coupling the elevator slips to the means for mechanically inhibiting movement of the spider control valve. For example, the link may be a Bowden cable where movement of the elevator slips causes a corresponding movement of the core of the cable which is connected to the means for inhibiting movement of the spider control valve.
It will be appreciated that the apparatus may also comprise a mechanically operated valve for controlling the supply of pressurised fluid to move the elevator slips between a gripping position and a release position. This valve may be operated by a lever which also projects through said guide plate. Preferably, when the guide plate is in its first position, the lever may be moved to open the elevator slips, whilst when the guide plate is in its second position, movement of the lever to open the slips is prevented.
In alternative embodiments of the invention, the mechanically operated valve for controlling the supply of pressurised fluid to move the spider slips between a gripping position and a release position may be operated by a switch, knob, or the like, with movement of the knob, switch, etc being inhibited to prevent the valve being operated to open the spider slips when the elevator slips are not correctly closed.
An additional user operable locking means may be provided for preventing accidental movement of the guide plate between the first and second positions.
In alternative embodiments of the invention, the apparatus comprises a second valve for directly controlling a supply of pressurised fluid to move the elevator slips between a gripping position and a release position, wherein said means for mechanically inhibiting movement of the first mentioned valve comprises a mechanism for meshing said first and second valves together.
Preferably, the first and second valves are capable of controlling the flow of pressurised air and hydraulic fluid. More preferably, the first and second valves are ball valves.
Preferably, the first and second valves may each be rotated between a first position in which the associated set of slips is caused to be closed and a second position in which the associated set of slips is caused to be open. More preferably, the meshing of the valves results in the locking of the first valve in the first position, when the second valve is in the second position, and the release of the first valve when the second valve is rotated from the second to the first position. The meshing of the valves may also result in the locking of the second valve in the first position, when the first valve is in the second position, and the release of the second valve when the first valve is rotated from the second to the first position.
The first and second valves may each comprise a substantially cylindrical body member rotatable around its longitudinal axis. Each cylindrical body has an arcuate section cut away, and the cylindrical bodies are arranged co-axially so that when the first valve is located in the first position, and the second valve is located in the second position, part of the second valve is located in the cut away of the valve, and vice versa when the first valve is located in the second position and the second valve is located in the first position.
Preferably, the means for mechanically inhibiting movement of the spider slips control valve further comprises sensor means for detecting when the elevator slips are in the correct gripping position. The sensor means is coupled to a mechanism for locking said first valve in the first position when the elevator slips are detected to be open, thus preventing rotation of the first valve from the first to the second position, and the release of the second valve.
Preferably, second sensor means is provided for detecting when the spider slips are in the correct gripping position. The second sensor means is coupled to a mechanism for mechanically locking the second valve in the first position when the spider slips are detected to be open, thus preventing rotation of the second valve from the first to the second position, and the release of the first valve.
The first and second detector means and the respective valve locking mechanisms ensure that a valve cannot be moved from the first to the second position to open the associated slips, unless the other set of slips are detected to be closed.
In certain embodiments of the invention, the first and second sensor means comprise respective piston and cylinder arrangements arranged beneath the slips of the elevator and spider. Each piston and cylinder arrangement is coupled hydraulically or pneumatically to the corresponding locking mechanism. Each locking mechanism may comprise a hydraulically or pneumatically operate locking rod which is moveable between a position in which the rod engages the corresponding valve and a position in which the rod is disengaged from that valve.
The apparatus may comprise a mechanical link coupling the elevator slips to the means for mechanically inhibiting movement of the spider control valve. For example, the link may be a Bowden cable where movement of the elevator slips causes a corresponding movement of the core of the cable which is connected to the means for mechanically inhibiting movement of the first valve.
Preferably, said valves for directly controlling the supply of pressurised fluid to move the spider and spider slips are mechanically operated valves which are operated manually. Alternatively however, the valves may be operated by electrical motors, solenoids, etc, and/or may be remote controlled (e.g. using radio, infra-red, or ultrasonic signals).
In one embodiment of the invention, said means for mechanically inhibiting movement of said valve comprises a sensor coupled to the elevator slips and arranged to sense movement of the elevator slips between an open and a closed position, the sensor being coupled to an electronic controller arranged to control a means for mechanically inhibiting movement of said valve.
According to a second aspect of the present invention there is provided a method of controlling the gripping and releasing of a tubular and comprising mechanically inhibiting movement of control means for directly controlling a flow of fluid to raise and lower a set of spider slips, when a set of slips of an elevator are not correctly gripping the tubular, such that the spider slips cannot be moved from a gripping to a release position.
Preferably said control means is a valve. However, the control means may be any other suitable apparatus such as a pump.
According to a third aspect of the present invention there is provided a method of gripping and releasing a tubular, the method comprising the steps of:
According to another aspect of the present invention there is provided apparatus for gripping and releasing a tubular, the apparatus comprising:
According to another aspect of the present invention there is provided apparatus for gripping and releasing a tubular, the apparatus comprising:
According to another aspect of the invention there is provided apparatus for gripping and releasing a tubular, the apparatus comprising:
For a better understanding of the present invention and in order to show how the same may be carried into effect reference will now be made by way of example to the accompanying drawings, in which:
a illustrates schematically a hydraulic system for controlling the elevator and spider of the arrangement of
b illustrates schematically a hydraulic system for controlling the elevator and spider of the arrangement of
c illustrates schematically a modified hydraulic system for controlling the elevator and spider of the arrangement of
A conventional system for handling tubulars using an elevator and spider arrangement has been described above with reference to
With reference to
Both the spider control valve 18 and the elevator control valve 20 are operated by respective levers 22,23. In order to close a set of slips 14,15 which are currently in the release position, the lever of the corresponding control valve is moved for a short time (e.g. a few seconds) to a “close” position. After the slips have been moved, the lever is returned to a central “neutral” position. Similarly, in order to open a set of slips 14,15 currently in a closed position, the corresponding lever is moved for a short time to an “open” position before being returned to the central neutral position. Each lever 22, 23 therefore has three positions; open, close, neutral. In the arrangement shown in
In order to control the operation of the levers 22, 23, the control valves 18,20 are mounted directly beneath a guide plate 24 (in the schematic illustration of
In the first operational position, the elevator control valve lever 23 can be moved from the neutral position to both the open and close positions, whilst the spider control valve lever 22 may be moved between the neutral and the close position. In the second operational position of the guide plate 24, the elevator control valve lever 23 must remain in the close position, whilst the spider control valve lever 22 may be moved from the neutral position to both the open and close positions.
With reference again to
The operation of the control system of
The position of the piston within the arrangement 28 tracks the position of the elevator slips 15 relative to the elevator body. Movement of the piston within the cylinder causes fluid to be expelled from the cylinder, through the supply lines 30 into the top of the cylinder of the arrangement 31. This causes the piston 35 to be withdrawn into the cylinder, moving the locking rod 32 away from the guide plate 24. When the elevator slips 15 have been lowered to the correct position in which they engage the body of the pipe length 34, the rod 32 is disengaged from the guide plate 24. In this position, the guide plate 24 can be moved by the operator to the left providing that both levers 22,23 are held in the close position. The lever 22 can then be operated to open the spider slips 14. This configuration is illustrated in
In the event that the operator moves the elevator control valve lever 23 to the close position whilst the elevator 13 is located at too high a position with respect to the upper length of drill pipe length 34, it is possible that the elevator slips 15 may close around the junction between the upper box of the pipe and the main body of the pipe (the situation illustrated in
If this situation arises, the piston of the sensor arrangement 28 will not be sufficiently withdrawn into the cylinder. The volume of fluid transferred to the arrangement 31 will not be sufficient to fully disengage the rod 32 from the guide plate 24. It will not therefore be possible for an operator to move the guide plate 24 to the left, and to open the spider slips 14. This embodiment of the present invention therefore provides a mechanical “sequencer” for the spider and elevator control valves 18,20.
When the valve 20 is subsequently operated to raise the elevator slips 15 (following the opening and closing of the spider slips 14), pressurised fluid drives the piston 42 out of its chamber. The pressurised fluid expelled from the chamber is in turn forced into the chamber(s) of the elevator slip drive arrangements 17, causing the elevator slips 15 to be raised. The valve 43 is provided to compensate for leaks, and ensures that sufficient fluid is available to fully open the elevator slips 15 when required.
With reference to
Pressurised fluid is supplied to the input of the valve switch 51 via a supply line 54 (which is coupled to a pressurised source of fluid which is not shown in the drawing). The output of the valve switch 51 is provided to the input of a delay circuit. This circuit comprises a one way flow regulator 55 which allows the compressed air from the output of the valve switch 51 to be fed to the input of an accumulator 56. The output of the accumulator 56 is provided to a control input of a second valve switch 57. The main input of the second valve switch 57 is coupled to the supply line 54. The output of the second valve switch 57 is provided to an input of the piston and cylinder arrangement 31, which input is situated in front of the head of the piston 35.
In the event that the elevator slips 15 close about the main body of the drill pipe 34, the slips 15 will be lowered relative to the elevator 13 to the required extent. The contact member 53 will contact the valve switch 51, causing the switch to open. Compressed air will flow from the supply line 54, through the flow regulator 55 to the input of the accumulator 56. Pressure builds up in the accumulator 56 until the pressure at the output of the accumulator 56 causes the second valve switch 57 to open. The time taken for the accumulator 56 to charge to a sufficient pressure to activate the second valve switch provides a short time delay between the closure of the elevator slips 15 and the possible release of the guide plate 24. As long as the second valve switch 57 remains closed, no pressure is present at the head of the piston 35 and the piston remains in its fully extended position in which the guide plate 24 is locked in its rightmost position. However, when the second valve switch 57 is opened, compressed air from the supply line 54 is conducted to the head of the piston 35 causing the piston to be retracted within its cylinder. The retraction of the piston 35 causes the guide plate 24 to be released. Assuming therefore that the operation of the lever 23 has resulted in the elevator slips 15 being moved to their correct lowered or closed position, the operator can slide the guide plate 24 to its leftmost position. The operator can then operate the lever 22 of the spider control valve 18 to move the spider slips 14 to their raised or open position. The elevator 13 then takes the full weight of the drill pipe string 33. This configuration is illustrated in
In the event that the elevator slips 15 grip around the box of the drill pipe 34, the contact member 53 attached to the slip support ring 29 will not contact and open the valve switch 51. Thus, no pressure will be applied to the head of the piston 35 and the guide plate 24 will remain locked in its rightmost position. In this position, the lever 22 operating the spider control valve 18 cannot be moved from its neutral position to open the spider slips.
When the pressure in the accumulator 64 reaches a predefined level, the pressure causes a valve switch 65 to move from a closed position in which no compressed air is passed from the supply line 54 to the piston head of the piston 35, to an open position in which compressed air is provided to the piston head. Therefore, when the elevator slips 15 are raised (or are jammed at an intermediate position), the piston 35 remains in its fully extended position, locking the guide plate 24 in its rightmost position. However, when the elevator slips 15 are correctly lowered, the piston 30 is withdrawn within the cylinder 29 and movement of the guide plate 24 is allowed.
With reference to
Each of the control valves 108, 120 comprises a cylindrical top plate 122, 123 and a cylindrical body member 124, 125 depending from the top plate. Both the top plate and the cylindrical body are rotatable together about their longitudinal axes, within the valve housing 126. As can be seen in
Each of the valve cylinders 124, 125 is arranged to rotate a ball member within a spherical socket formed in the valve housing. Each ball member has two bores extending through it in a transverse plane. The bores are arranged to couple fluid flow lines (leading to the piston and cylinder arrangements 106, 107 and slip closure sensors to be described below) to a source of pressurised hydraulic fluid P and to a tank for draining fluid. The advantage of the particular valve arrangement described here is that it can handle both air (pneumatic) and hydraulic fluid without leakage, although only the use of hydraulic fluid is described here.
The spider 102 and elevator 103 are provided with respective slip closure sensors 129, 130. Considering the spider slip closure sensor 129, this comprises a piston and cylinder arrangement, with a rod 131 extending from the piston head 132 being in contact with associated slips 104. When the spider slips 104 are open, the piston is extended whilst when the slips are fully closed the piston is compressed within the cylinder. Hydraulic fluid flow lines 133, 134 are coupled to the cylinder in front of and behind the piston head. The hydraulic lines 133,134 are coupled to a piston driven locking mechanism 135, in front of and behind the piston head of that mechanism. When the spider slips 104 are moved from the open to the fully closed position, fluid is expelled from the bottom of the cylinder of sensor 129, through the line 134, causing a rod 136 of the locking mechanism 135 to be retracted into the cylinder. Fluid expelled from the cylinder of the mechanism 135 flows through line 133 into the top of the cylinder of the sensor 129. The elevator slip closure sensor 130 operates in a similar manner to control a locking rod 137 of a locking mechanism 138. It will be understood from
The operation of the system of
When the elevator slips are fully lowered, the piston of the sensor 130 is fully depressed. This in turn results in the locking rod 137 of the locking mechanism 138 being fully retracted, releasing the spider control valve 108. Because of the new location of the cut out in the cylindrical plate 123 of the elevator control valve 120, the spider control valve can now be rotated to conduct fluid to the piston and cylinder arrangement 106 to raise the spider slips 104. The raising of the spider slips 104 is detected by the sensor 129, and when the slips 104 are fully raised, the result is that the locking rod 136 is fully extended. This prevents rotation of the elevator control valve 120 to open the elevator slips 105.
At this stage, all of the weight of the tubular is taken by the elevator 102, whilst the accidental opening of the elevator slips 105 is prevented. The tubular may now be lowered through the spider 102. When the tubular is at the correct height, the spider control valve 108 can be rotated (the locking rod 137 is at this stage retracted and the valves are meshed to allow rotation of the spider control valve) to engage the spider slips 104. Both the spider and the elevator are now holding the tubular. The sensor 129 detects closure of the spider, and causes the locking rod 136 to retract, releasing the elevator control valve 120. The elevator control valve 120 can then be rotated to raise the elevator slips 105. This completes one cycle of operation.
The system of
b illustrates a control system for the apparatus of
There is illustrated in
Each pressure compensation circuit comprises a valve which is opened or closed when the corresponding slip set is opened or closed, with the valve being coupled to a reservoir (or accumulator) 507. When a valve is open and the apparatus is heating up, expanding fluid may flow through the valve from the hydraulic circuit and expands into the accumulator. In the same way, when the apparatus is cooling, fluid is sucked from the accumulator, through the valve, into the hydraulic circuit.
With reference to
Both the spider control valve and the elevator control valve are operated by respective levers 209,210. In order to close a set of slips which are currently in the release position, the lever of the corresponding control valve is moved to a “close” position. Similarly, in order to open a set of slips currently in a closed position, the corresponding lever is moved to an “open” position. In the arrangement shown in
In order to control the operation of the levers 209,210, the control valves are mounted directly beneath a guide plate 211 (in the schematic illustration of
In the first operational position, the elevator control valve lever 210 can be moved between both the open and close positions, whilst the spider control valve lever 209 is held in the closed position. In the second operational position of the guide plate 211, the elevator control valve lever must remain in the close position, whilst the spider control valve lever may be moved between the open and close positions.
Sensor arrangements 213,214 are coupled to each of the spider and the elevator. These may be electrical, optical sensors, etc, and are arranged to detect when the slips of the spider and elevator are in the open and the closed positions. Both sensor arrangements are electrically coupled to a PLC 215. The PLC contains logic for analysing the outputs of the sensors and controlling a pair of locking rods 216,217 accordingly. The locking rods may be driven by solenoids in response to control signals generated by the PLC, and are arranged to lock the guide plate in either its leftmost or rightmost position. When the PLC detects that the slips of the spider are closed, the rightmost locking rod is withdrawn, allowing the guide plate to be slid to the right, thus releasing the lever controlling the elevator slips (in this position, the left most locking rod snaps back into a locking position). This lever can then be moved to open the elevator slips. Similarly, when the elevator slips are subsequently closed (after for example the connection of a further tubular to a string), the left most locking rod is withdrawn, allowing the guide plate to be slid to the left, releasing the spider slip control lever which can be moved to open the spider slips. The right most locking rod has by this time snapped back to the locking position.
The stroke measurement can be used to monitor slip movement while taking over the string load to analyse the performance of the actual grip, i.e. as a quality control measurement.
It will be appreciated by the person of skill in the art that various modifications may be made to the above described embodiment without departing from the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0026997.7 | Nov 2000 | GB | national |
| 0116170.2 | Jul 2001 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB01/04911 | 11/5/2001 | WO | 00 | 10/10/2003 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO02/36927 | 5/10/2002 | WO | A |
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|---|---|---|---|
| 3906813 | Webber et al. | Sep 1975 | A |
| 4042123 | Sheldon et al. | Aug 1977 | A |
| 4676312 | Mosing et al. | Jun 1987 | A |
| 5791410 | Castille et al. | Aug 1998 | A |
| 6386282 | Jansch | May 2002 | B1 |
| 6626238 | Hooper | Sep 2003 | B1 |
| Number | Date | Country |
|---|---|---|
| 1 099 824 | May 2001 | EP |
| 9404788 | Mar 1994 | WO |
| 9831914 | Jul 1998 | WO |
| 9900577 | Jan 1999 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20040188098 A1 | Sep 2004 | US |
