Patent Application
20050205269
The present invention relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a deep set packer with hydrostatic setting actuator.
In relatively deep wells, sufficient hydrostatic pressure exists for use in setting a packer. Typical hydrostatic set packers for use in deep wells have actuators which include annular piston areas formed between concentric tubular members. Unfortunately, the large hydrostatic pressures found in deep wells tend to deform these concentric tubular members, so that the actuators are unable to operate satisfactorily. For example, using conventional hydrostatic set packers it has not yet been possible to satisfactorily set the packers at pressures greater than 19,000 psi.
Therefore, it may be seen that it would be very beneficial to provide improved hydrostatic set packers for use in deep wells.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a packer and an actuator therefor are provided which are configured for use in high hydrostatic pressure environments. Associated methods are also provided.
In one aspect of the invention, a packer for use in a subterranean well is provided. The packer includes an actuator for setting the packer. The actuator includes multiple pistons circumferentially spaced apart from each other.
In another aspect of the invention, an actuator for use in a well packer is provided. The actuator includes multiple pistons, each of which is received in a respective one of multiple bores. The actuator further includes a force transmission device. Each of the pistons is releasably coupled to the force transmission device.
In yet another aspect of the invention, a method of setting a packer in a subterranean well is provided. The method includes the steps of: increasing pressure on the packer in the well; and displacing multiple pistons relative to respective multiple bores of an actuator of the packer in response to the pressure increasing step, thereby setting the packer in the well.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of a representative embodiment of the invention hereinbelow and the accompanying drawings.
Representatively illustrated in
As depicted in
Thus, the packer 12 is capable of both sealing and anchoring a tubular string 20 in the wellbore 14. Note that, although the wellbore 14 is depicted in
In one beneficial feature of the packer 12, an actuator 22 of the packer is positioned longitudinally between the seal elements 16 and the slip assembly 18. The actuator 22 produces both upwardly and downwardly directed forces when it is actuated, and these forces are transmitted directly from the actuator to each of the seal elements 16 and the slip assembly 18. In this manner, the forces produced by the actuator 22 are more efficiently utilized in the packer 12 than in conventional hydrostatic set packers, resulting in more satisfactory and reliable sealing and anchoring of the tubular string 20.
However, it should be clearly understood that it is not necessary in keeping with the principles of the invention for the actuator 22 to be positioned between the seal elements 16 and the slip assembly 18. The actuator 22 could instead be positioned below the slip assembly 18 or above the seal elements 16, for example. The embodiments described herein are used only as examples to illustrate applications of the principles of the invention, and are not to be taken as limiting the invention.
Referring additionally now to
Furthermore, the actuator 22 includes a setting initiation device 32. This device 32 is used to prevent the actuator 22 from actuating until a predetermined pressure on the packer 12 is reached, at which point the device permits the actuator to actuate and set the packer. Prior to application of the predetermined pressure, pressure in the well 10 causes the pistons 24 to exert an upwardly directed biasing force on the ring 30, and also causes the device 32 to exert a downwardly directed biasing force on the ring.
The downwardly directed force is greater than the upwardly directed force. However, when the predetermined pressure is applied, a rupture disc 34 of the device 32 is ruptured, thereby exposing an atmospheric chamber 46 (see
Note that the chamber 46 may be at atmospheric pressure when the actuator 22 is initially installed, or it could be at another pressure which is less than the pressure expected in the well at the location at which the actuator is to be positioned when it is actuated. It is not necessary in keeping with the principles of the invention for the chamber 46 to be at atmospheric pressure at any particular time, although in a preferred embodiment, the chamber is at atmospheric pressure when the actuator 22 is installed in the well. However, another pressure could be used if desired, such as another pressure less than hydrostatic pressure in the well at the location where the actuator 22 is to be positioned.
In
Upward displacement of any of the pistons 24 causes upward displacement of the ring 30. However, since each of the pistons 24 is releasably coupled to the ring 30, it is not necessary for all of the pistons to displace in order for the ring to displace. Thus, the ring 30 can displace upward with less than all of the pistons 24.
In
This is a very beneficial feature of the actuator 22, since it still permits the actuator to set the packer 12, even though one or more of the pistons 24 experiences a malfunction. For example, if there are ten of the pistons 24 and one of them experiences a malfunction, then about 90% of the maximum setting force can still be output by the actuator 22 to set the packer 12. In deep wells, where a round trip to replace a malfunctioning packer is extraordinarily time-consuming and expensive, this feature is very desirable.
Referring additionally now to
Each piston 24 includes an elongated extension 38 which extends through a respective one of multiple openings 40 formed through the ring 30. The openings 40 are circumferentially spaced apart in the ring 30, corresponding to the spacing of the pistons 24 in the bores 36 of the structure 26. A shoulder 42 formed on each of the extensions 38 is larger than the opening 40 through which the extension 38 extends, so that upward displacement of the piston 24 causes the shoulder to engage the ring 30 and displace it upward with the piston. However, note that the ring 30 can be displaced upwardly without the piston 24 displacing upward.
Each of the pistons 24 is depicted as being made up of multiple elements, an extension 38 threaded into a seal-carrying member 44, but it will be appreciated that the pistons could be made up of more or less elements in keeping with the principles of the invention. The bores 36 in which the members 44 are received are separate from each other, and are preferably at atmospheric pressure when the actuator 22 is used with the packer 12 (i.e., an atmospheric chamber exists in each bore 36 above the member 44). Thus, each of the bores 36 may be separately pressure-checked prior to running the actuator 22 (e.g., by pulling a vacuum on the individual bores and checking for leakage), and a leak into one of the bores after running the actuator will not affect operation of the pistons 24 in the other bores.
Note that the bore 36 above each member 44 may be at atmospheric pressure when the actuator 22 is initially installed, or it could be at another pressure which is less than the pressure expected in the well at the location at which the actuator is to be positioned when it is actuated. It is not necessary in keeping with the principles of the invention for the bore 36 above each member 44 to be at atmospheric pressure at any particular time, although in a preferred embodiment, the bore above each member is at atmospheric pressure when the actuator 22 is installed in the well. However, another pressure could be used if desired, such as another pressure less than hydrostatic pressure in the well at the location where the actuator 22 is to be positioned.
Due to the unique construction and configuration of the actuator 22, the relatively small diameter multiple pistons 24 and bores 36 are not deformed significantly when exposed to high pressures in a well. By circumferentially spacing apart the bores 36 in the structure 26, the bores are supported by the sidewall of the structure surrounding each bore. In addition, since the pistons 24 are not annular-shaped, they are not deformed significantly by the pressure applied thereto. Thus, the actuator 22 is capable of satisfactory operation at pressures in excess of 19,000 pounds per square inch in a well.
The setting initiation device 32 includes the chamber 46 between two sets of seals 48, 50. It will be readily appreciated by one skilled in the art that, when pressure is applied to the actuator 22 in the well 10, and the setting initiation device 32 is in the configuration shown in
When the predetermined pressure is reached, the rupture disk 34 ruptures, and the chamber 46 is exposed to the pressure in the well 10. Thus, the downwardly directed force formerly produced by the setting initiation device 32 is eliminated, and the upwardly directed force produced by the pistons 24 displaces the ring 30 upwardly (upon shearing shear screws 56 in the setting initiation device 32).
Positioned above each of the shoulder screws 52 is an elongated member 58 of the force transmission device 28. The force transmission device 28 includes six of the members 58 in this embodiment. The members 58 extend through respective openings 60 (see
In
Referring additionally now to
When the members 58 displace upwardly, the piston 66 will be displaced upwardly by the members and will apply a compressive force to the seal elements 16, causing them to extend outwardly into sealing engagement with the wellbore 14. The piston 66 provides a backup, in case the other pistons 24 fail to generate enough force (for example, if one or more of the pistons 24 malfunctions) to displace the members 58 upward and compress the seal elements 16 sufficiently. To utilize the piston 66 as a backup, a pressure differential is applied from an interior flow passage 68 (formed longitudinally through an inner tubular mandrel 70 of the packer 12) to an exterior of the packer. When a sufficiently large pressure differential is applied, shear screws 72 will shear and the piston 66 will be displaced upwardly by the pressure differential to compress the seal elements 16.
The lower end 62 of the actuator 22 abuts the slip assembly 18. When the actuator 22 elongates (between the upper ends 64 of the members 58 and the lower end 62 of the actuator), a downwardly directed force is applied from the lower end of the actuator to the slip assembly 18. This downwardly directed force causes the slip assembly 18 to extend outward into gripping engagement with the wellbore 14.
Note that, because the actuator 22 is positioned between the seal elements 16 and the slip assembly 18, the actuator is able to apply a compressive force to the seal elements and to the slip assembly 18, without the need for the force to be transmitted through one of these to get to the other. In addition, the actuator 22 is preferably not secured directly to the mandrel 70, but is instead reciprocably mounted on the exterior of the mandrel. Thus, when the actuator 22 elongates, the same force applied upwardly by the actuator via the members 58 toward the seal elements 16 is also applied downwardly by the actuator via the lower end 62 toward the slip assembly 18 (i.e., the forces are equal, but oppositely directed).
Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are contemplated by the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.
