VALVES

Abstract: There is disclosed a valve for closing a well bore to flow therethrough automatically in response to the loss of a controlled condition. The valve has springs 34,35 in which energy may be generated, in response to bleeding off of pressure above the closed valve. So long as the controlled condition is maintained, the return of a pressure balance across the closed valve will permit the release energy generated in one 35 of the springs to open the valve. The loss of the controlled condition released further energy generated in the other spring 34 to close the valve.

Description: This invention relates generally to valves, and, more particularly to improvements in valves to the type which are adapted to fail closed in response to the loss of a controlled condition. In one of its important aspects, this invention relates to valves of this type for use in controlling flow through a well bore below the earth's surface. Some prior valves of this latter type, often known as "storm chokes", are usually installed in the lower end of a production tubing for closing it in response to the velocity of the flow of well fluid therethrough, and thus, for example, to fail closed in the event of a blowout of the well. In such valves, the velocity at which the valve closes, and thus the controlled condition, may be changed by adjustment of the sizes of the orifices in the body of the valve through which the well fluid flows, or the force of a spring urging the closure member of the valve to open position, or both. If, however, the pressure of the formation from which the fluid is produced has dropped to a low level, adjustment of either or both of the orifice sizes and the spring force may seriously interfere with production. In other prior valves of this type, the closure member is adapted to be held open by hydraulic control fluid, which may be supplied thereto from a source at the head of the well, but spring pressed to closed position in response to the reduction in pressure of the control fluid below a predetermined low value. This loss in pressure of the control fluid may in turn occur in response to a predetermined fluid pressure condition, such as a rapid loss of wellhead flow pressure indicative of a blowout, or other controlled condition. Since valves of the latter type require a fluid conduit extending between the wellhead and the fluid responsive operator for the closure member and thus a long response time, they are ordinarily installed at the mud line of an offshore well, and thus do not provide protection for the full length of the tubing, as in the case of the velocity type valves. Also, it would be necessary to recomplete a well in order to replace the storm choke with a surface controlled valve. These and other problems could be overcome if the valve could be controlled by means at the surface requiring no physical connection with the valve, and thus installable deep in the well, as in the case of storm chokes, but at the same time independently of the condition of the well fluid, as in the case of surface controlled valves. It has been proposed to operate a valve or other mechanism deep within a production string of a well bore by transmitting electrical signals from the subsurface level to the valve through the earth. Such a valve requires a battery pack to provide the power necessary to control the valve in response to the receipt of a signal. Due to power drain from the battery pack, which is especially rapid in well bores where the temperature may be as high as 300°F, the energy available at the subsurface level would be limited, especially over a long period of time. This would be a particular problem in the case of a subsurface valve of the type described which may be left in the well for years, and which may have to operate - i.e., open, close, and then reopen - many times, whether due to an unavoidable loss of the controlled condition or a planned loss for test purposes. It is the primary objective of this invention to provide a valve of this latter type which may be installed deep in the well bore, and which is controllable independently of velocity or flow lines connecting it to the surface, but which is suited for operation in response to communication systems having subsurface power sources which are susceptible to depletion over the anticipated period of usage of the valve. A more particular object is to provide such a valve which is self energised in the sense that it does not draw on the subsurface power source for either moving to open or closed position, but only for the purpose of providing a relatively small force to hold it open for so long as the controlled condition is maintained. Still a further object is to provide a valve as described which may be interchanged with a storm choke controlling an existing well. The invention provides a valve comprising a body having a flowway therethrough, a closure member movable between positions opening and closing the flowway, and energy storage means to provide mechanical energy for moving the closure member from one of its positions to the other characterised by means and responsive to differential pressure established across the closure member when closed to store mechanical energy in the energy storage means, one part of the energy stored in the storage means being effective to open the valve on reduction of differential pressure, a latch to hold the closure member open, a second part of the energy stored in the storage means being effective for closing the valve on release of the latch, a control device to produce a retaining force to retain the latch in holding position, the latch being released when the force is removed in response to a received signal or failure of the device. When the valve is installed within a well bore, the pressure differential may be created by bleeding off the well fluid pressure in the well bore above the closed closure member, and then reduced by restoring the well fluid pressure above the closure member, so as to substantially equalize the pressure across the closure member. Consequently, the only power required is that necessary to provide a force to hold the further stored energy, which force, as will be apparent from the description to follow, may be of a very minor magnitude. In the preferred and illustrated embodiment of the invention, the energy is stored in spring means. In the preferred valve, a control device includes an electric power source and a solenoid to be energised by the power source in response to a signal transmitted from a location remote from the valve, for preventing release of the second part of said stored energy so long as them delivery of power from the power source is adequate to activate the solenoid, said solenoid being inoperable to prevent release of the second part of the stored energy when said power is lost as a result of the interruption of said signal and/or power drain from the power source. Preferably the valve has a sealed chamber in which the power source and other electrical components of the communication system may be contained for protection from the surrounding environment, and, more particularly, having such a chamber which does not require a seal between the mechanical components of the valve and the electrical components. Due to an efficient mechanical connection between the actuator and the means in which the further energy is generated, only small power is required to control the valve, even over a period of years. Thus, the invention contemplates that the valve may be opened and closed repeatedly upon interruption of the signal, either for the purpose of providing fail safe control, or for test purposes in order to be assured that the valve is functioning properly and thus capable of providing fail safe control, if needed. Preferably, the retainer and closure member are so held and released by means which include toggle links connected at one end to the body, and means including a rod connected to the other end of the toggle links to extend them when the closure member is open and collapse them when the closure member and retainer are released for movement to their second position. The solenoid holds the links in extended position so long as the power level of the battery is maintained, and permits the links to collapse upon the loss of said power level. In the drawings, wherein like reference characters are used throughout to designate like parts:- Fig. 1 is a vertical sectional view of the valve supported within the lower end of a tubing string, and with the closure member in closed position; Figs. 1A-1A and 1B-1B are cross-sectional views of the valve, as seen long broken lines 1A-1A and 1B-1B, respectively, of Fig. 1; Fig. 2 is a vertical sectional view of the valve, similar to Fig. 1, but upon the bleeding of the pressure of well fluid from above the closure member so as to cause the retainer to move to its upper position, with the toggle links held in extended positions to which they were lifted upon raising of the retainer to its upper position and the solenoid energized; Figs. 2A-2A and 2B-2B are cross-sectional views of the valve, as seen long broken lines 2A-2A and 2B-2B, respectively, of Fig. 2; Fig. 3 is another vertical sectional view of the valve, similar to Figs. 1 and 2, but upon lowering of the closure member to its open position in response to balancing the pressure of well fluid across the closure member; Fig. 4 is still another vertical sectional view of the valve, similar to Figs. 1, 2 and 3, but upon retraction of the end of the solenoid, in response to the loss of power from the battery, so as to unlock the retainer and closure member and permit the closure member to be moved upwardly to the closed position of Fig 1; Fig. 5 is a side view of the control rod removed from the retainer, and as seen along broken lines 5-5 of Fig. 1; Fig. 6 is another side view of the rod, as seen along broken lines 6-6 of Fig. 2; and Fig. 7 is another cross sectional view of the valve, as seen along broken lines 7-7 of Fig. 1. With reference now to the details of the above described drawings, the lower end of a production tubing 10 is shown in each of Figs. 1 to 4 to extend within a well bore 11 which may be lined with casing, and to be packed off at 12 to close the annular space between it and the well bore above a production zone from which oil or gas is to be recovered through the tubing. As also shown in each of Figs. 1-4, the valve of the present invention, which is indicated in its entirety by reference character 13, is located in the well bore to control the flow of fluid through the tubing, and, more particularly, to fail closed upon the loss of a controlled condition, as will be described to follow. Thus, it is connected to the lower end of a tubular member 14 which is supported within the tubing string 10 by means of locking elements 15 received within a recess 16 in the bore of the tubing string 10, and then sealed with respect thereto by a packing 17 about the tubular member 14. As shown, the valve 13 includes a generally cylindrical body 18 having its open upper end threadedly and sealably connected to the lower end of tubular member 14, and having ports 19 in its side connecting with the well bore beneath the lower end of the tubing string 10. A seat 21 is formed on the body within the flowway between the ports and the open upper end of the body 18, and a closure member including a sleeve 22 is vertically reciprocal within the body between an upper position in which the sleeve engages the seat to close the valve, as shown in Figs. 1 and 2, and a lower position in which it is spaced from the seat, substantially at the level of the lower end of the ports 19, so as to open the flowway, as shown in Figs. 3 and 4. A retainer 23 is guideably reciprocal within the closure member sleeve 22 between an upper position with respect thereto, as shown in Figs. 2, 3 and 4, wherein its upper end provides an upwardly extending conical continuation of the upper end of the sleeve, and a lower position with respect thereto, as shown in Fig 1. The retainer is located in its upper position with respect to the closure member sleeve by the engagement of a sleeve 24 thereabout with the lower end of the closure member sleeve 22, and is located in its lower position with respect to the closure member sleeve by engagement of a shoulder 25 about the retainer with a seat 26 formed on the inner diameter of the sleeve 22. A piston 23A at the upper end of the retainer is sealably reciprocable within the closure member sleeve, so that, as will be described to follow, the retainer may be caused to reciprocate between its upper and lower position, in order to generate energy which is used in opening, closing and reopening the valve in response to the pressure of the well fluid above and below it when closed. The body of the valve includes a transverse wall 27 which separates it into an upper chamber in which the valve closure member and retainer are disposed, and a lower chamber C which, as will be described, is maintained at atmospheric pressure and in which the battery solenoid and other electrical components of the communication system for the valve are contained. A pin 28 extends upwardly from the wall 27 to provide a stop for engaging the lower end of the retainer and thus limiting its downward movement with respect to the valve body. The retainer is held against rotation with respect to the body by means of a rod 29 extending upwardly from the wall 27 into a longitudinal slot 30 formed on the inner diameter of the retainer adjacent its lower end. The slot is of such length that the rod remains within it during reciprocation of the retainer with respect to the valve body. Since the upward movement of the retainer with respect to the closure member sleeve is limited by engagement of sleeve 24 with the lower end of the valve member sleeve 22, the upward movement of the retainer with respect to the body is limited by engagement of the upper end of the valve member sleeve with the seat 21 of the valve body. Ports 31 are formed in the side of the valve body above the transverse wall 27 so that well pressure is balanced within and without the valve body beneath retainer piston 23A. Of course, when the valve member is in the open position of Figs. 3 and 4, the pressure of the well fluid above and below the closure member is substantially the same. On the other hand, when the valve member has been moved to the closed position of Figures 1 and 2, the well fluid above the closure member may be bled off so as to create an upwardly directed pressure differential across the closed valve member, which, for purposes previously mentioned and to be described in detail to follow, causes the retainer to be raised to the position of Fig. 2 in order to set or reset the valve for movement to its open position of Fig. 3. The retainer has a flange 32 about its lower end, and a stop 33 is mounted on the inner diameter of the body above the flange and generally intermediate the upper and lower ends of the body. A first coil spring 34 surrounds the retainer sleeve 24 and is compressed between the lower end of the valve closure member sleeve 22 and the flange 32 so as to urge the valve closure member upwardly with respect to the retainer sleeve, and a second coil spring 35 is disposed about the first coil spring and is compressed at its opposite ends between the stop 30 and the flange so that it urges the retainer downwardly with respect to the valve body, and thus, as shown in each of Figs. 1, 3 and 4, into a lower position in which the lower end of the retainer engages stop 28. When the valve is closed, as shown in Fig. 1, either upon installation or in response to the loss of the controlled condition, both the first and second springs are fully expanded or deenergized. Well fluid pressure above the closure member may be bled off to cause the retainer member to rise to the position of Fig. 2, and thereby compress and energize the springs in order to generate energy therein. The solenoid is energized to cause it to move to a position in whch the retainer is locked in its upper position with respect to the closure member, so long as the controlled condition has been established and maintained, in order to set or reset the valve. At this time, the pressure of well fluid above the closure member may be restored to substantially balance pressure across the valve, and thus permit the coil spring 35 to be deenergized or expanded so that the energy generated therein lowers the retainer and thus lower the closure member with retainer to open the valve, as shown in Fig. 3. As long as the controlled condition is maintained, the valve will remain open. However, when the controlled condition is lost, the retainer and closure member are unlocked to release the energy generated in the first coil spring 34 in order to move the closure member upwardly with respect to the retainer and into engagement with the seat 21 to close the valve, as shown in Fig. 1. As also shown in each of Figs. 1-4, a rod 40 extends longitudinally within the retainer, and has an enlarged head 41 at its upper end which fits closely within the upper hollow end of the retainer, and a lower end 42 which extends through a hole 47 in the transverse wall 27 of the body connecting the upper and lower chambers thereof. A pin 43 carried by the retainer projects into its inner diameter to a position beneath the enlarged head 41 of the rod when the retainer is in a lower position with respect to the rod, as shown in Figs. 1 and 5. As the retainer 23 moves upwardly, the pin 43 moves into the lower end of a slot 44, in the head of the rod, as shown in Figs. 2 and 2B, which slot, as shown in Fig. 6, extends at an angle with respect to the vertical so as to rotate the rod approximately 10° with respect to the retainer as the retainer moves to its upper position, as shown in Figs. 2 and 6. A pin 45 is also carried within a hole extending through the retainer at a location opposite the enlarged head 41 of the rod and thus in a position to move above shoulder 26 on the inner diameter of the sleeve, as well fluid pressure above the retainer is bled off to cause it to be moved upwardly to the position of Fig. 2, and pin 43 on the retainer to move into slot 44. As shown in Fig. 2B, the resulting rotation of the head of the rod cams the inner end of pin 45 out of a slot 46 in the right side of the head, and beyond the outer diameter of the retainer above the seat 26. At this time then, the retainer is locked against downward movement with respect to the valve member sleeve, and, conversely, the valve member sleeve is locked against upward movement with respect to the retainer. Since the sleeve 34 has engaged the lower end of the closure member sleeve, the retainer is held against further upward movement with respect to the closure member, which of course is seated and thus prevented from moving up. As shown in Figs. 1A and 2A, as well as in Figs. 1-4, the lower end 42 of the rod which extends through hole 47 in the wall 27 is connected to an arm within the atmospheric chamber C so as to rotate the arm from the position shown in Fig. 1A to the position shown in Fig. 2A as the retainer moves upwardly from the position of Fig. 1 to the position of Fig. 2, and thus as the pin 43 moves into the slot 44 in the head on the upper end of the rod so as to transmit rotation to the rod relative to the retainer. Each outer end of the arm 50 is pivotally connected to one arm of a toggle links 51 having its other arm pivotly connected to a bracket 52 extending downwardly from the transverse wall 27 within the atmospheric chamber, and the arms of the toggle links are connected to one another by means of a rod 53 extending between them. As will be understood from the drawings, rotation of the arm 50 with the control rod 40 will move the outer ends of the toggle links further apart, and thus move the toggle links from the collapsed position of Fig. 1 to the extended position of Fig. 2. Swivel pin connections are provided between the ends of the arms and the links, as well as between the brackets and the links. A platform 54 is suspended from the lower side of the transverse wall 27 by bracket arms 58 extending downwardly from the wall to support a solenoid 59 with an extendible and retractable end 60. When the toggle links are extended, and the solenoid is energized, the end 60 of the solenoid is raised to the position shown in Fig. 2 to hold the links extended so long as the controlled condition is maintained. On the other hand, when the valve is open, as shown in Fig. 4, and the controlled condition is lost, the solenoid is inoperable to oppose the force of a small spring acting 48 between the body of the solenoid and an end of the solenoid opposite the end 60. Thus, the links are moved off dead center to permit them to be collapsed, in response to rotation of the control rod, as shown in Fig. 4, and thus release the closure member for upward movement from the position of Fig. 4 to the position of Fig. 1. A torque tube 61 surrounds the control rod and is anchored at one end to the transverse wall 27 of the valve body and at the upper end to the head of the control rod. The torque tube thus provides a spring force for urging the control rod from the position of Fig. 3 to the position of Fig. 4, so as to rotate the enlarged upper end of the control rod to a position in which slot 46 is opposite the inner end of pin 45. Thus, as shown in Figs. 1 and 1B, the pin may be urged inwardly from above shoulder 26 and into slot 46 to free the closure member sleeve for moving upwardly with respect to the retainer, and thus from the position of Fig. 4 into the closed position of Fig. 1 in engagement with the seat 21. Also, of course, the torque tube closes the annular space about the rod as the rod rotates between its alternate positions and thus closes the chamber C. The solenoid 59 is electrically connected to a battery pack within a container 62 mounted within the atmospheric chamber C, as shown in broken lines in Figs. 1 to 4. When well pressure above the closure member has been bled off and the solenoid has been energized to retain the toggle link extended, as shown in Fig. 2, the links are held extended so long as the controlled condition is maintained to cause the battery to activate the solenoid. To summarize operation of the valve, and assuming it to be in the reset position of Fig. 2 wherein energy is generated in both of the coil springs, and the solenoid to have been activated to engage its end 60 with the rod 53 extending between the toggle links, and thus hold the toggle links in extended position, well pressure may be equalized across the closed valve member to permit energy generated in coil spring 35 to be released in order to move both the valve member and the retainer downwardly from the closed position of Fig. 2 to the open position of Fig. 3. Although this removes pin 43 from slot 44, the rod is not free to rotate, and the pin 45 continues to remain in a locked position to hold the retainer in its upper position with respect to the closure member, as long as the solenoid is rendered operative. However, when the solenoid is rendered inoperative, spring 48 moves the toggle links off center to permit them to be collapsed by the spring force in the torque tube. As the arm 50 is so rotated, the head at the upper end of the control rod is rotated to a position in which the slot 46 therein is opposite the pin 45 so as to receive the pin, as shown in Fig. 4, and thereby unlock the retainer and closure member sleeve to permit the sleeve be moved upwardly by the inner coil spring 34 from its lower position with respect to the retainer to its upper position with respect thereto and thus to move the upper end of the closure member into engagement with the seat 21 to close the valve, as shown in Fig. 1. As previously described, the controlled condition in the illustrated embodiment of the invention is the maintenance of a power level in the battery pack sufficient to activate the solenoid, and thus hold the toggle links in extended positions. This invention contemplates that a signal may be transmitted from the earth's surface to a switch in a receiver in the container 62 for closing it to electrically connect the battery pack to the solenoid, and thus activate the solenoid so long as the power level of the battery pack has not been drained below the necessary level. This signal could, as previously mentioned, be electromagnetically communicated through the earth itself, and the receiver could include an antenna adapted to receive and transmit the signal to the switch. In any event, this signal may be selectively interrupted so as to deactivate the solenoid by disconnecting it from the batter pack, and thus rendering the solenoid inoperative to hold the toggle links. As also previously mentioned, however, the valve is fail-safe even if the signal continues to be transmitted, but the level of the power of the battery pack has fallen below the predetermined level whereby the solenoid is rendered inoperative to hold the energy generated in the inner coil spring. From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which will are inherent to the apparatus. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is comtemplated by and is within the scope of the claims.

Claims: A valve comprising a body 18 having a flowway 19, 20 therethrough, a closure member 22 movable between positions opening and closing the flowway, and energy storage means 34, 35 to provide mechanical energy for moving the closure member from one of its positions to the other characterised by means 23, 23A and 32 responsive to differential pressure established across the closure member 22 when closed to store mechanical energy in the energy storage means 34, 35, one part of the energy stored in the storage means 34, 35 being effective to open the valve on reduction of differential pressure, a latch 26, 45 to hold the closure member open, a second part of the energy stored in the storage means 34, 35 being effective for closing the valve on release of the latch, a control device 41, 50, 51, 59, 60, 62 to produce a retaining force to retain the latch in holding position, the latch being released when the force is removed in response to a received signal or failure of the device. A valve as in Claim 1, wherein said control device includes an electric power source 62 and a solenoid 59 to be energised by the power source in response to a signal transmitted from a location remote from the valve, for preventing release of the second part of said stored energy so long as the delivery of power from the power source is adequate to activate the solenoid, said solenoid being inoperable to prevent release of the second part of the stored energy when said power is lost as a result of the interruption of said signal and/or power drain from the power source. A valve as in Claim 1 or Claim 2, wherein the means in which energy is stored includes spring means 34, 35. A valve as in Claim 3, wherein there are two spring means and the second part of the stored energy in one spring means 34 moves the closure member from open to closed position. A valve as claimed in Claim 2, wherein there are two spring means 34, 35, and a spring retainer 23, 23A, 32 movable with respect to the closure member, the first spring means 35 acting between the retainer and body 18, the second spring means 34 acting between the retainer and closure member, whereby in response to said pressure differential across the closure member, while the closure member is in its closed position, said retainer and closure member shift from a first to a second position with respect to one another, in order to store energy in said first and second spring means, said retainer and closure member being locked in said second position by said latch means 26, 45, so that energy stored in said first spring means 35 is operable, upon said reduction in the pressure differential, to move the closure member with the retainer from its closed to its open position, the closure member remaining in open position so long as said power level is adequate, said retainer and closure member being released upon loss of adequate power level, to permit energy stored in said second spring means to move said closure member and retainer from their second to their first position with respect to one another, whereby the closure member may be moved to closed position by the energy stored in the second spring means. A valve as in any one of the preceding Claims 1 to 5, wherein the valve is for controlling flow through a well bore, and the body flowway is adapted to form a continuation of the well bore. A valve as in Claim 4 as dependent on Claim 2, wherein the closure member includes a sleeve 22 reciprocable within the body between an upper position closing the flowway and a lower position opening the flowway, and further comprising a spring retainer 23, 23A, 32 reciprocable between upper and lower positions with respect to the closure member, first spring means 35 compressed between the body and retainer to urge the retainer downwardly with respect to the body, second spring means 34 compressed between the closure member and retainer to urge the retainer upwardly with respect to the closure member, said retainer including piston means 23A sealably slidable within the closure member sleeve to urge the retainer to its upper position, in response to a reduction in the pressure of well fluid above the closure member, while the closure member is in its closed position, in order to generate energy in said first and second spring means, a rod 40 mounted on the retainer for movement between first and second positions with respect thereto, means 41 responsive to movement of the rod into its second position for retaining the latch in position to hold the retainer in its upper position with respect to the closure member, and to movement of the rod into its first position for releasing said latch to release said retainer for movement to its lower position with respect to the closure member, means 50, 51 for moving the rod to its second position when the retainer is moved to its upper position to store energy in the first and second spring means and the closure member is in its closed position, whereby said retainer is urged by well fluid to its lower position, when the pressure differential across the piston means is reduced, so that energy stored in the first spring means is effective to move the closure member with the retainer to open position, the latch being moveable into a position for holding the rod in its second position, and thus holding the closure in its open position, so long as power from said source is adequate, said latch being inoperable to hold the rod when delivery of power from said source falls below adequate, and means 61 urging the rod from its second to its first position so as to release the retainer from its upper position with respect to the closure member and permit energy stored in the second spring means to move the closure member to closed position. A valve as in Claim 7, wherein the body is adapted to be located within the well bore and has ports 18 in the side thereof connecting with an open upper end 20 of the body to form the flowway. A valve as in Claim 8, wherein there is a seat 21 in the flowway and the closure member sleeve 22 is adapted to engage the seat.

Inventors: AKKERMAN, NEIL HOOVER
Applicants: AVA INTERNATIONAL CORPORATION
Application year: 1985
Main classification: E21B34
IPC codes: E21B34