Patent Application
20050247455
The present invention relates to a hydraulic circuit connected to an injector for injecting coiled tubing into a well, and a method of controlling the gripping of the tubing associated therewith.
Many coiled tubing injectors utilize a hydraulic circuit to control movement of one or more components of the injector in order to grip and advance the coiled tubing through the injector and to the well.
Several potential problems arise during the operation of a typical injector hydraulic circuit. In particular, if the diameter of the tubing increases during the operation of a typical injector hydraulic circuit, there may be an unsafe pressure increase in the circuit. Also, many injector hydraulic circuits require a human operator to move near the injector during operation to adjust the gripping pressure on the tubing, thus increasing the risk of harm to the operator.
Further, if there is a loss of pressure to the injector hydraulic circuit, the tubing will be released, thus creating a “runaway” situation whereby the released tubing could cause harm to the operator and significantly damage the injector and the well. Current runaway-prevention solutions include using a shut-off valve to isolate the injector hydraulic circuit after a loss of pressure, or connecting a check valve upstream of the injector hydraulic circuit to hold the pressure in the injector hydraulic circuit. Although these solutions prevent a complete loss of pressure to the injector hydraulic circuit, they do not provide an easy and safe way for the human operator to resume control of the injector hydraulic circuit after the pressure has been restored. In addition, neither of these solutions enables the gripping pressure on the tubing to be increased in the event of an unforeseen failure in operator-house pressure.
Therefore, what is needed is an injector for advancing coiled tubing into a well that overcomes these problems.
a-4b are diagrammatic views depicting a hydraulic circuit according to another embodiment of the invention.
Referring to
A spool of coiled tubing 18 is positioned at a predetermined location away from the injector 10. Unspooled tubing 20 passes from the spool and under a measuring device, such as a wheel 22, and between several (seven in the example of
The injector 10 includes a frame 28 having a base 28a, and a pair of substantially similar carriages 30a and 30b mounted on the base via a pair of carrier lugs 31a and 31b. The carriages 30a and 30b drive the tubing 20 into the stuffing box 16 for passage through the well-head 14 and into the well 12.
The carriages 30a and 30b are depicted in greater detail in
Two rods 34a and 34b extend out from the cylinders 32a and 32b, respectively, with one end of each rod being connected to its corresponding piston and the other end connected to the carriage 30a by two mounting brackets 35a and 35b, respectively. The cylinders 32a and 32b are connected in a hydraulic circuit (not shown) so that fluid is selectively introduced and discharged from the cylinders to cause corresponding contraction and extension of the cylinders, as will be further described. This contraction and extension of the cylinders 32a and 32b causes corresponding movement of the carriages 30a and 30b towards each other to grip the tubing 20, and away from each other to release the tubing. It is understood that two other cylinders (not shown), identical to the cylinders 32a and 32b, are connected to the carriages 30a and 30b on the other sides of the carriages.
The carriage 30a includes a gripping chain 36 extending between, and engaged with, two spaced sprockets 37 (one of which is shown in
The outer surface of the chain 40 is in engagement with the inner surface of the chain 36 and is free wheeling about its sprockets 42. It is understood that a motor (not shown) is provided to drive at least one of the sprockets 37, and therefore the chain 36. The engagement between the chains 36 and 40 is such that the chain 36 drives the chain 40 which functions to support the chain 36.
Since the carriage 30b is identical to the carriage 30a the above components of the carriage 30a will be referred to by the same reference numerals in connection with the carriage 30b.
During the general operation, and referring to
Referring to
The control circuit 52 includes a source 54 of pressurized hydraulic fluid which is connected to a check valve 56 in the circuit 50 via a hydraulic work line 58 that also extends from the check valve to the input of a control valve 60 in the circuit 50. The check valve 56 permits fluid flow in a direction indicated by the flow arrows, but prevents flow in the opposite direction. An accumulator 64 is connected to the line 58 between the check valve 56 and the control valve 60 via a line 66. The accumulator 64 is adapted to store fluid from the circuit 50 and introduce the stored fluid into the circuit under conditions to be described.
An output from the valve 60 is connected to a counterbalance valve 68 via a hydraulic work line 70. The valve 68 is normally closed but can be opened under conditions to be described. A hydraulic work line 72 extends from the line 58 at a location downstream of the valve 60 to a check valve 74 and, from the latter valve, to the line 58 at a location upstream of the valve 60. The check valve 74 permits fluid flow in a direction indicated by the flow arrows, but prevents flow in the opposite direction. It is understood that the valve 60 includes a relief mechanism (not shown) and its function will be described in detail.
The counterbalance valve 68 is also connected to a work line 76 which, in turn, is connected to one end portion of each cylinder 32 via a plurality of branch lines 78, 80, 82 and 84. Thus, fluid flows from the source 54, through the valves 56, 60, and 68 and to the cylinders 32 for actuating the cylinders in a manner to be described. It is understood that the valve 68 includes a check valve that will permit fluid flow in this manner but will prevent fluid flow in the opposite direction.
The fluid source 54 is also connected to the injector hydraulic circuit 50 via a hydraulic work line 86 which, in turn, is connected to the other end portion of each cylinder 32 via a plurality of branch lines 88, 90, 92 and 94 to enable fluid to flow from the cylinders back to the source in a direction indicated by the flow arrows.
The line 86 is also connected to a pilot-operated check valve 96, via a pilot line 98, and the check valve 96 is, in turn, connected to the line 58 via a hydraulic work line 100. The check valve 96 normally prevents flow through the line 100 and is adapted to open when fluid is received from the pilot line 98 to permit flow in the direction indicated by the flow arrows under conditions to be described. It is understood that fluid flow between the source 54 and the lines 58 and 86 can be selectively and remotely controlled by an operator in any conventional manner.
An output from the valve 60 is also connected to a counterbalance valve 102 via a pilot line 104 which extends to a relief valve 106 located in the control circuit 52. The valve 102 is normally closed but is opened under conditions to be described, and the valve 106 is adjustable to control the pressure reduction across the valve 60, from the line 58 to the line 70. The valve 60 is configured to allow some fluid to pass through it from the line 58 to the line 70, while allowing some fluid to be diverted, or bled off, from the valve to the line 104 and the valve 102, for passage to the relief valve 106, all under conditions to be described.
A manifold 110 is provided in the control circuit 52 and is connected to a switching valve 112 via a line 114. Although not shown in the drawings in the interest of clarity, it is understood that the manifold 110 receives fluid from the source 54. The switching valve 112 is connected to the counterbalance valves 68 and 102 in the injector hydraulic circuit 50 via lines 116 and 118, respectively which act as pilot lines for the counterbalance valves and, as such, control the operation of the valves.
A pressure gauge 120 is also provided in the control circuit 52 and is connected to the line 76 in the circuit 50 via a line 122. Thus, the pressure gauge 120 can measure pressure in the line 76 and therefore the pressure in the cylinders 32. The relief valve 106 and the switching valve 112 are connected, via a line 124 and a line 126, respectively, to a return manifold, or tank, 127. The switching valve 112 normally connects the line 116 to the manifold 110 via the line 114, but is adapted to be switched to terminate this connection and connect the line 116 to the tank 127 via the line 126, under conditions to be described.
In the circuit 50, the check valve 96 and the control valve 60 are connected, via the line 100 and a line 130, respectively, to a tank 132. Thus fluid can be discharged from the valves 60 and 96 into the tank 132 under conditions to be described.
The counterbalance valves 68 and 102 are normally closed, but are adapted to open in response to a predetermined fluid pressure being applied to the valves by the lines 116 and 118, respectively. When the valve 68 is in its open position, fluid is allowed to flow from upstream of the valve 60, through the valves 60 and 68, and to the cylinders 32 as indicated by the flow arrows. Fluid is also allowed to flow in the reverse direction from the cylinders 32, through the valve 68 and to the tank 132, either via the control valve 60 or via the check valves 74 and 96 in a manner to be described. When the valve 68 is in its closed position, fluid is still allowed to flow from upstream of the valve 60 to the cylinders 32 via the valve 60 and the check valve included in the valve 68. However, reverse fluid flow from the cylinders 32 to the tank 132 via the valve 68 is not allowed when the valve 68 is in its closed position. When the valve 102 is in its open position, fluid is allowed to flow from the valve 60 to the valve 106 as indicated by the flow arrows. When the valve 102 is in its closed position, fluid is not allowed to flow from the valve 60 to the valve 106. Reverse fluid flow through the valve 102, that is, fluid flow from the valve 106 to the valve 60, is not possible, regardless of whether the valve 102 is in its open or closed position.
Assuming that the tubing 20 (
Fluid also flows from the source 54 to the manifold 110 in the control circuit 52 and pressurizes the manifold to a pressure that also corresponds to the maximum gripping pressure of the carriages 30a and 30b. Assuming that the switching valve 112 is in its normal mode in which it connects the manifold 110 to the line 116, fluid flows from the manifold 110, through the valve 112, and to the lines 116 and 118 to pressurize the lines. The counterbalance valves 68 and 102 are normally closed and, the lines 116 and 118, respectively serve as a pilot line for the valves and thus open the valves and allow pressure to be transmitted through the valves.
The output pressure from the valve 60 is transmitted to one end of each of the cylinders 32 via the lines 70,76, 78, 80, 82 and 84. Assuming that the rods of the cylinders 32 are in an extended position as a result of a previous operation, the rods will retract to the positions shown in
Due to the opening of the counterbalance valve 102, some of the fluid from the valve 60 will bleed off and pass through the pilot line 104, the counterbalance valve 102, and to the relief valve 106. The valve 60 and the relief valve 106 are designed so that the relief valve can control the amount of flow that can be bled off from the valve 60 in the above manner, and therefore the fluid pressure passing to the cylinders 32. In particular, to increase the amount of force on the tubing 20, the relief valve 106 is adjusted to reduce the amount of flow being bled off from the valve 60, thereby increasing the output pressure in the line 70. To decrease the amount of force on the tubing 20, the relief valve 106 is adjusted to increase the amount of flow being bled off from the control valve 60, thereby decreasing the output pressure in the line 70.
When the fluid applied to the cylinders 32 is at the desired pressure corresponding to the desired pressure, or load, that the carriages 30a and 30b exert on the tubing 20, the relief valve 106 is no longer adjusted and the output pressure in the line 70 remains constant, thereby applying constant loading on the tubing 20. In each of the above modes, the pressure applied to the cylinders 32 can be measured using the gauge 120.
In situations where the tubing 20 is part of a string having a varying diameter, constant pressure on the cylinders 32 can always be maintained despite the fact that the diameter of the tubing varies as it passes through the injector 20. Specifically, if the diameter of the tubing 20 increases during the above mode, it causes a corresponding extension of the cylinders 32 from the retracted position of
If the diameter of the tubing 20 decreases, additional hydraulic fluid will enter the cylinders 32 from the fluid source 54 via the valve 60 in the manner described above, thereby maintaining constant pressure on the cylinders 32. Assuming that the carriages 30a and 30b are gripping the tubing 20 in accordance with the foregoing, if there is a significant loss in the fluid pressure available from the source 54 for whatever reason, the pressure levels in the line 58 and the line 116, which are both normally at the maximum gripping fluid pressure discussed above, will drop significantly. When this occurs, there is no immediate effect on the pressure in the line 58 or the accumulator 64 since the check valve 56 maintains the maximum gripping fluid pressure downstream from its location in the line 58. Likewise, the closed check valve 96 prevents fluid from flowing from the line 58 to the tank 132 via the line 100, thereby holding the pressure level in the line 58 downstream of the check valve 56 at the maximum gripping pressure.
In response to any significant loss in the fluid pressure available from the source 54, the pressure at the manifold 110 also drops since the manifold is supplied with fluid from the source 54. Thus, the pressure in the line 116 is lowered accordingly. Since the line 116 serves as the pilot line for the counterbalance valve 68, this pressure drop causes the counterbalance valve 68 to close, thereby holding the gripping pressure in the cylinders 32. Similarly, the pressure drop in the line 116 causes a pressure drop in the pilot line 118, thus causing the counterbalance valve 102 to close and prevent fluid from being bled off from the valve 60 via the pilot line 104.
Also in response to the above significant loss in the fluid pressure available from the source 54, the normal operating pressure placed on the cylinders 32 will not only be maintained as discussed above, but the pressure on the cylinders 32 will be increased for safety purposes. In particular, the output pressure of the control valve 60, and therefore the pressure on the cylinders 32, will increase because the pressure in the line 58 downstream of the check valve 56 is higher than the pressure in the line 70 and fluid can no longer be bled off from the control valve 60 via the pilot line 104, as discussed above. This pressure increase is possible due to the fact that the above-mentioned check valve included in the counterbalance valve 68 will allow pressure to be transmitted to the cylinders 32, but will prevent pressure to be transmitted in the opposite direction from the cylinders 32, even though the counterbalance valve 68 is closed. Also, additional fluid provided to the line 58 by the accumulator 64 will be transmitted to the cylinders 32 through the valve 60, the check valve included in the counterbalance valve 68, and the lines 58, 70, 76, 78, 80, 82 and 84, to place additional pressure on the cylinders. Thus, the cessation of pressure bleeding from the control valve 60 and the additional pressure provided by the accumulator 64 will result in the gripping pressure provided by the cylinders 32 rising to a value that is significantly higher than the normal operating gripping pressure.
When the full fluid pressure in the source 54 is restored, the counterbalance valves 68 and 102 will automatically open again, allowing pressure to be bled off from the valve 60, thereby reducing the pressure to the cylinders 32. The gripping pressure will then be able to be controlled as usual by the relief valve 106. Thus, an operator does not have to leave the control circuit 52 to restart normal injector hydraulic circuit 50 control and operation.
The circuits 50 and 52 are also adapted to operate in an emergency mode in the event it is desired to terminate the normal operation of the injector 10 for some unforeseen reason. In this case an operator would manually switch the switching valve 112 so that the above-mentioned connection between the line 116 and the manifold 110 is terminated and a connection is established between the line 116 and the tank 127 via the line 126, as discussed above. Thus fluid in the line 116 is passed to the tank 127 resulting in a significant pressure drop in the line 116, similar to the pressure drop experienced when the fluid pressure at the source 54 is lost as discussed above.
When the pressure in the line 116 drops, the counterbalance valve 68 closes, thus holding the gripping pressure in the cylinders 32. Similarly, the counterbalance valve 102 closes due to the drop in pressure in the line 116 and therefore the line 118, thus preventing pressure from being bled off from the control valve 60. As a result, the pressure at the valve 60, and therefore the pressure in the line 70, increases and is transmitted to the cylinders 32 via the check valve included in the closed counterbalance valve 68, as discussed above, and the lines 76, 78, 80, 82 and 84. The output pressure will increase all the way up to the maximum gripping pressure since the fluid source 54 is still providing maximum gripping pressure to the injector hydraulic circuit 50 via the line 58. Thus, the accumulator 64 does not have to provide additional pressure to the cylinders 32 as in the previous mode. The output pressure of the control valve 60, and therefore the pressure placed on the cylinders 32, ceases to increase and remains constant after reaching the maximum gripping pressure.
The cylinders 32 will remain at the maximum gripping pressure until the operator manually switches the switching valve 112 to connect the line 116 back to the manifold 110 upon resolution of the emergency situation. When this occurs, the pressure in the line 116 will increase back up to the maximum gripping pressure, resulting in the opening of the counterbalance valves 68 and 102. This allows the resumption of pressure bleeding from the control valve 60, thereby decreasing the pressure placed on the cylinders 32 via the open counterbalance valve 68. The operator may then control the gripping pressure using the relief valve 106, as described above.
When it is desired to open the carriages 30a and 30b (
To achieve this opening action, the fluid source 54 is activated and pressurized fluid is applied to the line 86 by a proper valve, switch, or the like. This results in fluid flowing to the cylinders 32 via the lines 88, 90, 92 and 94, in a direction opposite the flow arrows shown in
During this cylinder open mode, the counterbalance valve 102 remains open because the line 116 is still pressurized at the maximum gripping pressure as discussed above. However, pressure is not bled off from the control valve 60 to the valve 102 since the pressure in the line 70 is greater than the pressure in the line 58 and therefore the counterbalance valve 102 is not employed.
The embodiment of
The sub-circuit 136 is substantially the symmetric equivalent of the sub-circuit 134, containing the same components that are found in the sub-circuit 134, which are given the same reference numerals with prime designations. Thus, the line 76′ is connected to the two cylinders 32 associated with the circuit 136 via the lines 82′ and 84′ and the line 86′ is connected to the two cylinders 32 via the lines 92′ and 94′. Also, the sub-circuit 134′ includes a gauge 138′ connected to the line 70 via a line 140′, and a gauge 142′ connected to the accumulator 64′. The line 100′ is connected to the tank 132 via the line 143. A line 144′ is provided that connects the line 56′ to the line 143 which, in turn, is connected to the tank 132, and a manual open/close valve 146′ is connected in the line 144′. The line 148 connects the line 130′ to the line 143 which, in turn, is connected to the tank 132. The sub-circuits 134, 136 are connected to the line 58 by two branches 58a and 58a′ which, in turn, are connected to the check valves 56 and 56′, respectively.
The control circuit 52′ shown in
In operation of the embodiment of
The gauges 138, 138′ are used for troubleshooting purposes and measure the output pressures of the control valves 60, 60′ in the lines 70, 70′, respectively. The gauges 142, 142′ measure the pre-charge pressure of the accumulators 64, 64′, respectively, and the manual open/close valves 146, 146′ may be used to drain the hydraulic circuit 50 of its fluid, draining the fluid to the tank 132 via the lines 144, 144′, respectively, and via the line 143.
In the control circuit 52′, the gauge 150 measures the approximate sum of the pressure in the lines 70 and 70′, respectively, that is, the output pressure from the control valves 60 and 60′, respectively. The pressure gauge 120 measures the pressure being applied only to the two cylinders 32 associated with the sub-circuit 134 while the gauge 152 measures the pressure being applied to the two cylinders 32 associated with the sub-circuit 136.
The operation of the embodiment of
It is understood that variations may be made in the foregoing without departing from the scope of the invention. For example, although four cylinders 32 are used in the injector 10 and the injector hydraulic circuits 50 and 50′, the quantity of cylinders 32 may vary as long as an evenly distributed load is applied to the tubing 20 via the gripping elements 38. For the embodiment of
Further, in addition to the injector 10, other configurations and/or types of injectors for injecting coiled tubing may be employed in conjunction with the injector hydraulic circuit 50 or 50′, as long as the injector types include hydraulic actuated cylinders.
Still further, the number of sub-circuits in the embodiment of
Still further, one or more embodiments of
Any foregoing spatial references, such as “side,” “above,” etc., are for the purpose of illustration only and do not limit the specific spatial orientation of the structure described above.
Although only two exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many other variations and modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such variations and modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.
