Spring assist system with positional feedback for carriers of snubbing slip bowls

Abstract

An apparatus comprising a slip bowl for supporting drill pipe within a well hole and a plurality of carriers associated with the slip bowl. The plurality of carriers are configured to move between an open position and a closed position. At least one spring assist mechanism are each associated with one of the plurality of carriers. The at least one spring assist mechanism biases the associated carrier to maintain the carrier in the open position.

Description

TECHNICAL FIELD

[0001] The present invention relates to slip bowls for snubbing equipment and hydraulic work over units, and more particularly, to a slip bowl including a spring assist system including a spring assembly for maintaining a position of a carrier of the slip bowl and a position sensor for tracking a position of the carrier within the slip bowl. In some embodiments, the spring assist system includes a pressurized gas spring, for example, a nitrogen gas spring.BACKGROUND

[0002] Snubbing slip bowls are utilized in pipe-heavy and pipe-light scenarios during hydraulic work over operations of pressurized oil wells. Some styles of slip bowls utilize gravity to maintain the operating path of the carriers when the bowl is upright in the pipe-heavy position. In the pipe-light operating mode, the slip bowl is mounted in an inverted orientation. Gravity, in the pipe-light mode, causes the carriers to fall out of position. A “top plate” is utilized to keep the carriers from falling out and hanging uselessly below the inverted slip bowl. However, even with the “top plate” in place, inverted slip bowls can fail to close consistently. Additionally, the “top plate” takes up space that could otherwise be used for other components within the equipment. Traditional slip bowls also lack a method for electronically sensing and indicating the position of the carriers during operation. This position data can be used for various tasks such as electronically interlocking a set of slip bowls or indicating to the operator when a mechanical failure has occurred in the equipment. The increased safety implications of knowing the position of the carriers at all times would be extremely advantageous.SUMMARY

[0003] The present invention, as disclosed and described herein, in one aspect thereof, comprises an apparatus including a slip bowl for supporting drill pipe within a well hole and a plurality of carriers associated with the slip bowl. The plurality of carriers are configured to move between an open position and a closed position. At least one spring assist mechanism is associated with each one of the plurality of carriers. The at least one spring assist mechanism biases the associated carrier to maintain the carrier in the open position.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] For a more complete understanding, reference is now made to the following description taken in conjunction with the accompanying Drawings in which:

[0005] FIG. 1 illustrates carriers of a slip bowl having a spring assist system in an open position;

[0006] FIG. 2 illustrates carriers of a slip bowl having a spring assist system in the closed position;

[0007] FIG. 3 illustrates a perspective view of a carrier of a slip bowl being held in the open position by the spring assist system;

[0008] FIG. 4 illustrates a perspective view of a carrier of a slip bowl being held in the closed position by the spring assist system;

[0009] FIG. 5 illustrates a perspective view of a spring assist system in an open position;

[0010] FIG. 6 illustrates a perspective view of a spring assist system in a closed position;

[0011] FIG. 7 illustrates a cross-sectional view of a spring assist system having positional feedback sensing;

[0012] FIG. 8 illustrates a block diagram of a control system for determining carrier position within a slip bowl; and

[0013] FIG. 9 illustrates a flow diagram of the process for determining carrier position using feedback from a spring assist mechanism.DETAILED DESCRIPTION

[0014] Referring now to the drawings, wherein like reference numbers are used herein to designate like elements throughout, the various views and embodiments of a spring assist system with positional feedback for carriers of snubbing slip bowls are illustrated and described, and other possible embodiments are described. The Figs. are not necessarily drawn to scale, and in some instances the drawings have been exaggerated and / or simplified in places for illustrative purposes only. One of ordinary skill in the art will appreciate the many possible applications and variations based on the following examples of possible embodiments.

[0015] Referring now to the drawings, and more particularly to FIG. 1, there is illustrated a slip bowl 102 having carriers 104 positioned in the open position. The carriers 104 support gripping inserts 105 that enable the carriers to grip drill pipe that is passing through the slip bowl 102. Snubbing slip bowls 102 are used in pipe-heavy and pipe-light scenarios within a snubbing jack during hydraulic work over operations of pressurized oil wells. Some styles of slip bowls 102 utilize gravity to maintain the operating path of the carriers 104 when the slip bowl 102 is upright in the pipe-heavy position. However, during pipe-light operation, the slip bowl 102 is mounted in an inverted orientation from that illustrated in FIG. 1 and gravity will bias the carriers 104 to fall out of position. As mentioned previously, a top plate (not shown) may be utilized to keep the carriers 104 from falling out and hanging uselessly below an inverted slip bowl 102. However, the top plate can cause inverted slip bowls 102 to fail to close consistently. Additionally, the top plate takes up space that could otherwise be used for other components within the drilling equipment.

[0016] Each of the carriers 104 is pivotally connected to a mid-portion of a respective shear arm 118 using a pivot bolt 119. Each shear arm 118 is mounted at its base to connecting shaft 120 and, under normal conditions, rotates with the connecting shaft to move the carrier 104 via the pivot bolt 119. However, when a predetermined torque between the shear arm 118 and a connecting shaft 120 is exceeded, a shear key between the shear arm and the connecting shaft will break and thereafter the shear arm will not reliably rotate identically with the connected shaft. This situation of a broken shear key may provide a further situation wherein the carrier 104 may not completely close around pipe within the slip bowl 102. Rather, in this situation, the shear arm 118 will not move the carrier 104 reliably between the open position and the closed position. This can result in failure of the gripping inserts 105 to engage the pipe string creating dangerous operating conditions.

[0017] The slip bowl 102 enables movement of the carriers 104 between the open position as illustrated in FIG. 1 and the closed position as illustrated in FIG. 2 responsive to movement of the actuator arm 106. The actuator arm 106 moves the carriers 104 between the open position of FIG. 1 and the closed position of FIG. 2 responsive to a hydraulic cylinder 107 moving between the retracted position shown in FIG. 1 that opens the carriers 104 and the extended position as shown in FIG. 2 that moves the carriers to the closed position. As the piston arm 109 of the hydraulic cylinder 107 extends outward from the hydraulic cylinder to the extended position, the actuator arm 106 rotates the connecting shafts 120 and the shear arms 118 to cause each of the carriers 104 to move towards a drill pipe within the slip bowl 102 and grip the drill pipe. The carriers 104 are maintained in either the open position of FIG. 1 or the closed position of FIG. 2 using a spring assist mechanism 108. The spring assist mechanism 108 consists of a spring cylinder 110 that is outwardly biased (i.e., biased to extend) and can move between an open (i.e., extended) position as illustrated in FIG. 1 and a closed (i.e., compressed) position as illustrated in FIG. 2. The spring assist mechanism 108 additionally includes a position sensor 112 for monitoring the position (e.g., extension or orientation) of the spring cylinder 110 as will be more fully described herein below. In some embodiments the position sensor 112 can be a linear position sensor, whereas in other embodiments it can be a rotary position sensor or an angular position sensor, provided the position sensor detects the current position of the spring cylinder 110 as it moves between its open position and its closed position. In the illustrated embodiment, the position sensor 112 is a linear variable differential transformer (LVDT) position sensor for monitoring the position of a magnet included within the spring cylinder 110 as will be more fully described herein below. A LVDT position sensor 112 is a device that measures the linear motion of an object (a magnet) and converts measured motion to an electrical signal.

[0018] The carriers 104 are connected to the spring assist mechanism 108 using a top bracket 114 that connects to the top alignment hole of the carrier 104. A lower mounting bracket 116 mounts the lower end of the spring assist mechanism 108 to the shear arm 118 of the carrier 104. Connection of the spring assist mechanism 108 to the carriers 104 biases the carriers to lie against the shear arm 118 when opening to prevents the carriers from moving out of position responsive to external forces such as gravity. While the illustration of FIGS. 1 and 2 illustrate the slip bowl 102 in a non-inverted position, it will be appreciated that if the slip bowl 102 were inverted the spring assist mechanism 108 would prevent gravity from pulling the carriers 104 downward and out of position within the slip bowl 102.

[0019] Referring now to FIG. 3, there is more particularly illustrated a perspective view of the carrier 104 and associated spring assist mechanism 108 connected to the slip bowl 102. A top end of the spring assist mechanism 108 can be connected to the carrier 104 using a top bracket 114, and a lower end of the spring assist mechanism can be connected to the shear arm 118 using a lower bracket 116. In the illustrated embodiment, a first end of the top bracket 114 is connected to a top end of the spring cylinder 110 using a first bolt 302 and a second end of the top bracket is connected to a top alignment hole of the carrier 104 using an alignment bolt 304, wherein the alignment bolt 304 is offset from the pivot bolt 119. Further, a first end of the lower bracket 116 is connected to a lower end of the spring cylinder 110 and a second end of the lower bracket is connected to the shear arm 118 near its base. When the actuator arm 106 moves the carrier 104 to the open position (i.e., via the action of the connecting shaft 120 and shear arm 118), the upper portion of the outwardly biased spring cylinder 110 will extend while pushing against the top bracket 114, thereby rotating the carrier around the pivot bolt 119 towards the base of the shear arm due to the offset between the alignment bolt 304 and pivot bolt 119 while the base of the spring cylinder remains in a fixed position with respect to the shear arm 118.

[0020] In a similar manner as shown in FIG. 4, when the actuator arm 106 moves the carrier 104 to the closed position around a drill string, the pivoting of the carrier around the pivot bolt 119 relative to the shear arm 118 will push the top bracket 114 against the outward bias of the spring cylinder 110 and force the top portion of the spring cylinder into the lower portion. The spring assist mechanism 108 will thus rotate to a position substantially perpendicular to the drill string wherein the lower end will rotate around the axis of the shear arm 118.

[0021] As previously described, the spring assist mechanism 108 includes a position sensor 112 to determine the current position of the carrier 104 in either the open position, the closed position or some intermediate position between the open and closed positions by detecting the current configuration of the spring cylinder 110 in either the open / extended configuration, the closed / compressed configuration or some intermediate configuration between the open / extended and closed / compressed configurations. In the illustrated embodiment, the position sensor 112 is a LVDT position sensor connected to a fixed portion of the spring cylinder 110 that can detect the movement of a magnet connected to a moving portion of the spring cylinder and thereby determine if the spring cylinder is in the open / extended configuration, the closed / compressed configuration or some intermediate configuration therebetween, as described more fully herein below.

[0022] Referring now to FIGS. 5 and 6, there are illustrated perspective views of the spring assist mechanism 108 in both the open / extended position (FIG. 5) and the closed / compressed position (FIG. 6). The spring assist mechanism 108 consists of the spring cylinder 110 having an internal cylinder or tube 502 that telescopically engages an outer cylinder or tube 504. The spring cylinder 110 is mounted to the slip bowl 102 using the top bracket 114 and a lower bracket 116. The top bracket 114 comprises an L-shaped member 506 having a tab portion 508 integrated therewith. The tab portion 508 defines a hole 510 therethrough for receiving the alignment bolt 304 that engages with the top alignment hole of the carrier 104. The tab portion 508 is inserted between a pair of arms within the carrier 104 having the alignment hole defined therein. The hole 510 aligns with the alignment hole of the carrier 104 and the alignment bolt 304 is inserted therethrough to secure the top bracket 114 to the carrier 104. A threaded bolt 512 is used for securing the top bracket 114 to the internal cylinder 502 of the spring cylinder 110.

[0023] A pair of support brackets 514 are used for supporting the LVDT position sensor 112 the support brackets 514 consist of a first member 516 and a second member 518 that are integrated with the outer surface of the outer cylinder 504 of the spring cylinder 110. The pair of support brackets 514 define an opening therein through which the LVDT position sensor 112 may be inserted. A securing bolt 520 and nut 522 are used for pinching the members 516 and 518 towards each other to secure the LVDT position sensor 112 between them. Control signals to and from the LVDT position sensor 112 are through a connection lead 113

[0024] The lower bracket 116 comprises a U-shaped bracket that is bolted to opposite sides of the outer cylinder 504 of the spring cylinder 110. The U-shaped bracket comprises a first support arm 530 and a second support arm 532 that are located on opposite sides of the outer cylinder 504. The first support arm 530 and second support arm 532 are interconnected by a backplate 534 that is integrally connected with each of the first and second support arms. The backplate 534 further defines a pair of mounting tabs 536 by which the lower bracket 116 is connected to the shear arm 118 of the slip bowl. The mounting tabs 536 define an opening through which a bolt 538 may be inserted in and secured with a nut 540. The bolt 538 will insert through a hole defined within the shear arm 118 and then through the opening defined in the mounting tabs 536 before the lower bracket 116 is secured using the nut 540.

[0025] Referring now to FIG. 7, there is provided a cross-sectional view of the spring assist mechanism 108 in accordance with one embodiment. As discussed previously, the top bracket 114 is mounted to the internal cylinder 502 using a bolt 512. The bolt 512 threadedly engages a threaded chamber 702 defined within the tab portion 508 of the top bracket 114. The L-shaped portion 500 of the top bracket 114 as well as the internal cylinder 502 define openings therein through which the bolt 512 may be passed to threadedly engage the threaded chamber 702 to secure the top bracket 114 to the internal cylinder 502.

[0026] The internal cylinder 502 telescopically engages the outer cylinder 504 through a sliding bushing 704 that interconnects the internal cylinder 502 with the outer cylinder 504. In the illustrated embodiment, the internal cylinder 502 and outer cylinder 504 are biased toward an extended position (which corresponds to the open position of the carrier 104) by a nitrogen gas spring 706. The nitrogen gas spring 706 is mounted within interior chambers defined within the internal cylinder 502 and the outer cylinder 504. Gas springs are well suited to provide the bias in the spring cylinder 110 because even when the gas spring is fully extended, the gas is already under pressure. This preloaded pressure generates an initial force (preload) without needing significant displacement or compression. In other embodiments, different types of springs may be used in the spring cylinder 110 to bias the cylinders 502, 504 or other movable portions.

[0027] The position sensing capabilities of the spring assist mechanism 108 are provided by the LVDT position sensor 112 and one or more magnets 708 mounted substantially near the base of the internal cylinder 502. The position of the magnets 708 is sensed by the LVDT position sensor 112 and the sense position information may then be provided to a control system associated with the spring assist mechanism 108 such that a position of the carrier 104 to which the spring assist mechanism 108 is connected may be determined. Thus, a determination may be made if the carrier 104 is in the completely open position, the completely closed position or in some position between these two extremes. As discussed previously, the LVDT position sensor 112 is maintained in a fixed position with respect to the outer cylinder 504 by a pair of support brackets 514.

[0028] Finally, the lower mounting bracket 116 is connected to the lower portion of the outer cylinder 504 in order to mount the spring assist mechanism 108 to the shear arm 118 of the carrier 104. This enables securing of the base of the spring assist mechanism 108 while the top bracket 114 secures the top of the spring assist mechanism 108.

[0029] Referring now to FIG. 8, there is illustrated a block diagram of a control system for determining the position of a carrier 104 within a slip bowl 102. One or more spring assist mechanisms 108 are each associated with a carrier 104 of a slip bowl 102 as described hereinabove with respect to FIGS. 1 and 2. The LVDT position sensor 112 within the spring assist mechanism 108 will generate positioning signals in transmit this to a controller 802. The controller 802 utilizes this information to determine the position of the carrier 104 associated with the spring assist mechanism 108. In this manner, the position of each of the carriers 104 within a slip bowl 102 may be known at any particular point in time.

[0030] Referring now to FIG. 9, there is illustrated a flow diagram of the process for determining positions of carriers 104 within a slip bowl 102. The LVDT position sensor 112 will sense at step 902 the position of a magnet 708 that is contained within a spring cylinder 110. The sensed magnet position information is transmitted at step 904 to the controller 802 by the LVDT position sensor 112. The controller 802 may then determine at step 906 a position of a carrier 104 associated with a received position signal. In this manner, the controller 802 may determine if the carrier 104 is opened, closed or at any positioned between the opened and closed positions.

[0031] It will be appreciated by those skilled in the art having the benefit of this disclosure that this spring assist system with positional feedback for carriers of snubbing slip bowls provides a improved system for both maintaining and monitoring carrier position him. It should be understood that the drawings and detailed description herein are to be regarded in an illustrative rather than a restrictive manner, and are not intended to be limiting to the particular forms and examples disclosed. On the contrary, included are any further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments apparent to those of ordinary skill in the art, without departing from the spirit and scope hereof, as defined by the following claims. Thus, it is intended that the following claims be interpreted to embrace all such further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments.

Claims

1. An apparatus comprising:a slip bowl for supporting drill pipe within a well hole;a plurality of carriers associated with the slip bowl, each of the plurality of carriers configured to pivot about a separate pivot point on the slip bowl between an open position and a closed position;a hydraulic cylinder connected to each of the plurality of carriers for moving the plurality of carries between the open position and the closed position; anda plurality of spring assist mechanisms each connected to one of the plurality of carriers, wherein the plurality of spring assist mechanisms biases the connected carrier to maintain the carrier in the open position after the hydraulic cylinder moves the connected carrier to the open position.

2. The apparatus of claim 1, wherein the plurality of spring assist mechanisms is further configured to provide position data with respect to a position of the connected carrier.

3. The apparatus of claim 1, wherein the plurality of spring assist mechanisms further comprises a spring cylinder for biasing the associated carrier to maintain the plurality of carriers in the open position.

4. The apparatus of claim 3, wherein the spring cylinder further comprises:a first tube;a second tube configured to telescopically slide into an interior of the first tube; anda sliding bushing located between the first tube and the second tube to enable the second tube to telescopically slide into the interior of the first tube.

5. The apparatus of claim 4, wherein the spring cylinder further comprises a gas spring contained within the interior of the second tube and the first tube, the gas spring biases the second tube to maintain the associated carrier in the open position.

6. The apparatus of claim 4 further comprising:at least one magnet connected to the second tube and configured to move with the second tube as the second tube moves telescopically with respect to the first tube; anda sensor fixedly connected to the first tube, the sensor detecting movement of the at least one magnet and generating signals responsive to the detected movement.

7. The apparatus of claim 1 further comprising a top bracket for connecting a top of the plurality of spring assist mechanisms to an alignment hole of the plurality of carriers.

8. The apparatus of claim 1 further comprising a lower bracket for connecting a lower portion of the plurality of spring assist mechanisms to a shear arm of the plurality of carriers.

9. An apparatus comprising:a slip bowl for supporting drill pipe within a well hole;a plurality of carriers associated with the slip bowl, each of the plurality of carriers configured to pivot about a separate pivot point on the slip bowl between an open position and a closed position; andplurality of spring assist mechanisms each connected to one of the plurality of carriers, wherein the plurality of spring assist mechanisms include a sensor therein to provide position data between the open position and the closed position with respect to a position of the connected carrier pivoting between the open position and the closed position.

10. The apparatus of claim 9, wherein the plurality of spring assist mechanisms further comprises a spring cylinder for biasing the associated carrier to maintain the plurality of carriers in the open position.

11. The apparatus of claim 9, wherein the plurality of spring assist mechanisms further comprises:a first tube;a second tube configured to telescopically slide into an interior of the first tube; anda sliding bushing located between the first tube and the second tube to enable the second tube to telescopically slide into the interior of the first tube.

12. The apparatus of claim 11, wherein the plurality of spring assist mechanisms further comprises a gas spring contained within the interior of the second tube and the first tube, the gas spring biases the second tube to maintain the plurality of carriers in the open position.

13. The apparatus of claim 11 further comprising:at least one magnet connected to the second tube and configured to move with the second tube as the second tube moves telescopically with respect to the first tube; anda sensor fixedly connected to the first tube, the sensor detecting movement of the at least one magnet and generating signals responsive to the detected movement.

14. The apparatus of claim 9 further comprising a top bracket for connecting a top of the plurality of spring assist mechanisms to an alignment hole of the plurality of carriers.

15. The apparatus of claim 9 further comprising a lower bracket for connecting a lower portion of the plurality of spring assist mechanisms to a shear arm of the plurality of carriers.

16. The apparatus of claim 9 further comprising a controller configured to determine a position of the plurality of carriers associated with the plurality of spring assist mechanisms responsive to the provided position data from the sensor.

17. An apparatus comprising:a slip bowl for supporting drill pipe within a well hole;a plurality of carriers associated with the slip bowl, each of the plurality of carriers configured to pivot about a separate pivot point on the slip bowl between an open position and a closed position;a hydraulic cylinder connected to each of the plurality of carriers for moving the plurality of carries between the open position and the closed position;a plurality of spring assist mechanisms each connected to one of the plurality of carriers, wherein the plurality of spring assist mechanisms biases the connected carrier to maintain the carrier in the open position after the hydraulic cylinder moves the connected carrier to the open position and provides position data between the open position and the closed position with respect to a position of the associated carrier as the associated carrier pivots between the open position and the closed position, the plurality of spring assist mechanisms comprising:a first tube;a second tube configured to telescopically slide into an interior of the first tube;at least one magnet connected to the second tube and configured to move with the second tube as the second tube moves telescopically with respect to the first tube; anda sensor fixedly connected to the first tube, the sensor detecting movement of the at least one magnet and generating signals responsive to the detected movement.

18. The apparatus of claim 17, wherein the plurality of spring assist mechanisms further comprises a spring cylinder for biasing the associated carrier to maintain the plurality of carriers in the open position.

19. The apparatus of claim 18, wherein the spring cylinder further comprises a nitrogen gas spring contained within the interior of the second tube and the first tube, the nitrogen gas spring biases the second tube to maintain the plurality of carriers in the open position.

20. The apparatus of claim 17 further comprisinga top bracket for connecting a top of the plurality of spring assist mechanisms to an alignment hole of the plurality of carriers; anda lower bracket for connecting a lower portion of the at least one spring assist mechanism to a shear arm of the plurality of carriers.

21. An apparatus comprising:a slip bowl for supporting drill pipe within a well hole;a plurality of carriers associated with the slip bowl, the plurality of carriers configured to move between an open position and a closed position;a hydraulic cylinder connected to each of the plurality of carriers for moving the plurality of carries between the open position and the closed position; anda plurality of spring assist mechanisms each connected to one of the plurality of carriers, wherein the plurality of spring assist mechanisms biases the connected carrier to maintain the carrier in the open position after the hydraulic cylinder moves the connected carrier to the open position; anda plurality of sensors each located in one of the plurality of spring assist mechanisms for measuring position data between the open position and the closed position with respect to a position of the connected carrier pivoting between the open position and the closed position.

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