ACTUATION MECHANISM FOR WATER HAMMER VALVE

Abstract

The present invention discloses an actuation mechanism for a water hammer valve. The water hammer valve is initially prevented from operating, and an actuation mechanism for the water hammer valve is actuated by dropping one or more balls or other objects onto the valve. Once actuated, the pilot and piston mechanism in the water hammer valve operate to produce hydraulic pulses from an upstream pressurized fluid.

Description

RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Patent Application No. 61/890,684, filed on Oct. 14, 2013, which is herein incorporated by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to an actuation mechanism for a downhole water hammer valve.

2. Description of the Related Art

Fluid is commonly pumped through a workstring of tubing (such as coiled tubing, or jointed tubing) inserted into a well to drill or to provide intervention services such as stimulation or milling of obstructions. U.S. Pat. No. 6,237,701 and U.S. Pat. No. 7,139,219 disclose hydraulic impulse generators incorporating self-piloted poppet valves designed to periodically stop the flow of fluid at the bottom end of the tubing. U.S. Pat. No. 8,528,649 (“the '649 Patent”) describes a percussive water hammer that generates axial loads on a workstring and pressure pulsations in the annulus between the workstring and the borehole or completion tubing. Each of these patents is incorporated herein by reference.

The percussive loads generated by the water hammer increase the lateral range of a workstring and improve the effectiveness of milling and drilling tools located at the end of a long workstring, particularly in extended reach horizontal wells. These pulses can also be used to generate a signal that can be used for seismic processing. The annulus pressure pulsations help to remove debris from the wellbore.

Workstrings often incorporate a jar that is actuated when the tubing becomes stuck. These tools incorporate a latch that releases when a tension or compression load is applied at some level that is higher than the normal levels required for operations. In the case of an up jar, a pull load releases a latch that allows the tool to extend freely over a fixed travel until it hits a hard stop. There are up jars and down jars and bidirectional jars. These tools were developed primarily for vertical drilling operations and are designed to be deployed near the neutral point where the drill collars transition from tension to compression during drilling operations. Locating and actuating jars is much more difficult in an extended reach horizontal well. The pull force must be transmitted to the tool through a curve where the borehole transitions from vertical to horizontal and through a long section of borehole that may have additional twists and turns. In the case of coiled tubing, the pull forces required to actuate the jar commonly exceed the design limits for the tubing and the fatigue life of the coil is reduced.

The water hammer valve can also be used to free downhole equipment including stuck workstring, downhole valves or obstructions in a borehole. As disclosed in the '649 Patent, the amplitude of the percussive load is limited by bypassing a portion of the flow through the valve in order to limit wear and tear on other downhole components such as motors, releases and measurement while drilling tools. If a tool becomes stuck the flow rate can be increased to increase the percussive force, and this commonly works to free the workstring.

The tool described in the '649 Patent, however, operates continuously and may be subject to wear on extreme reach well interventions or while operating on poor quality fluid laden with abrasive particles or abrasive weighted drilling mud. There would be a significant advantage if one were able to prevent a water-hammer valve, such as that described in the '649 Patent, from operating while running into the heel of a horizontal well, and actuating the valve only when it becomes difficult to feed the tubing into the well.

Directional drilling (DD) requires the use of measurement while drilling (MWD) tools that may be sensitive to downhole vibration. The water hammer valve pulsations may also interfere with the mud pulse data telemetry employed by DD systems. For this reason as well, it would be a substantial advantage if one were able to actuate the valve only when drilling progress slows or if the workstring (drillstring) becomes stuck.

A water hammer valve can also generate a seismic signal that can be used for seismic-while-drilling applications. This application requires operation on heavy mud that can cause increased wear of the tool. The seismic signal is only needed as the drill approaches a formation that requires a casing change. An actuation mechanism would allow the water-hammer valve to be turned on when needed for seismic work.

SUMMARY OF THE INVENTION

The present invention discloses an actuation mechanism for a water hammer valve. The water hammer valve is initially prevented from operating and an actuation mechanism for the water hammer valve is actuated by inserting one or more balls or other objects into pressurized fluid flow. The ball or balls once seated onto the valve actuate it, and the poppet assembly, containing a pilot and piston mechanism, in the water hammer valve operates to produce hydraulic pulses from and within an upstream pressurized fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and attendant advantages of an exemplary embodiment will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings:

FIG. 1A shows a plan view of the bottom of an exemplary pulse valve with one embodiment of the actuation mechanism of the present invention (hereafter referred to “the tool”);

FIG. 1B shows a longitudinal cross-section view of the tool taken along section line A-A in FIG. 1A;

FIG. 1C shows a transverse cross-section view of the tool taken along section line B-B in FIG. 1B;

FIG. 2A shows a plan view of the bottom of the pulse valve poppet assembly;

FIG. 2B shows a longitudinal cross-section view of the pulse valve poppet assembly taken along section line C-C of FIG. 2A.

FIG. 3A shows a plan view of the bottom of the upper manifold assembly;

FIG. 3B shows a longitudinal cross-section view of the upper manifold assembly taken along section line D-D in FIG. 3A;

FIG. 3C shows a longitudinal cross-section view of the upper manifold assembly taken along section line E-E (90 degrees counterclockwise from D-D) in FIG. 3A;

FIG. 4A shows a plan view of the lock assembly;

FIG. 4B shows a longitudinal cross-section view of the lock assembly taken along section line F-F in FIG. 4A;

FIGS. 5A and 5B show a plan view and a longitudinal cross-section view, respectively, of the upper portion of the tool after the balls have been dropped and just before they reach the ball seats;

FIGS. 6A and 6B show a plan view and a longitudinal cross-section view, respectively, of the upper portion of the tool with the balls seated;

FIG. 7A shows a plan view of the bottom of the tool;

FIG. 7B shows a longitudinal cross-sectional view of the middle portion of the tool taken along section line J-J in FIG. 7A with shear pins 44 broken. The lock assembly and poppet have moved to the first hard stop (the shear pin shear configuration);

FIG. 7C shows a longitudinal cross-sectional view of the middle portion the tool taken along section line K-K (90 degrees from J-J) in FIG. 7A in the same configuration as FIG. 7B;

FIGS. 8A and 8B show a plan view and a longitudinal cross-section view, respectively, of the middle portion the tool with shear pin 45 broken and the lock assembly moved to the hard stop;

FIGS. 9A and 9B show a plan view and a longitudinal cross-section view, respectively, of the middle portion the tool with the poppet assembly and stop rod moved to their uppermost positions;

FIGS. 10A and 10B, 11A and 11B, 12A and 12B show the middle portion of the tool with the poppet assembly in various stages during operation after actuation;

FIGS. 13A and 13B show a plan view and a longitudinal cross-section view, respectively, of another embodiment the tool with a latch mechanism in the locked state;

FIGS. 14A and 14B show a plan view and a longitudinal cross-section view, respectively, of the upper manifold assembly containing the latch mechanism in the locked state;

FIG. 14C shows a longitudinal cross section view of the upper manifold assembly containing the latch mechanism taken along section line T-T in FIG. 14B; and

FIGS. 15A and 15B show a plan view and a longitudinal cross-section view, respectively, of the tool with the latch mechanism in the released state.

DETAILED DESCRIPTION

It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. While a preferred embodiment of the invention is described herein, the invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings.

The operation and configuration of the poppet valve and pilot shift mechanism are described in U.S. Pat. No. 8,528,649.

FIG. 1B is a longitudinal cross-sectional view of a pulse valve with the ball-drop actuation mechanism (hereafter referred to as “the tool”) taken along section lines A-A in FIG. 1A. FIG. 1B shows a poppet assembly 12 coaxially disposed inside of a cartridge assembly 11, which is in turn coaxially disposed inside of a housing assembly 10. The housing assembly 10 comprises upper adaptor 15, housing 16, lower adaptor 17, and anti-wear rings 24. The upper adaptor 15 incorporates inlet threads and seals to connect fluid passage A to a supply tube and the lower adaptor 17 incorporates threads and seals and fluid passage H for fluid connection to downstream components of a bottomhole assembly such as a motor and mill or jetting head.

As shown in FIG. 2B, the poppet assembly 12 includes a piston 33 with poppet 31 attached at its distal end with a lower nut 32, and a pilot bushing 34 attached at its proximal end with upper nut 35. Returning to FIG. 1B, the poppet assembly 12 is able to move up and down axially inside of cartridge assembly 11, which comprises poppet seat 13, lower manifold 23, lower stop ring 22, lower cylinder 21, upper stop ring 20, upper cylinder 19, and upper manifold 18. A clamp nut 14 is threadably engaged with upper adaptor 15 of the housing assembly 10 to securely clamp the components of the cartridge assembly 11 inside the housing assembly 10.

With reference to both FIGS. 1B and 2B, a pilot 36, shown in FIG. 2B, is coaxially disposed inside of the poppet assembly 12 and slides axially between an upper and lower position. The poppet assembly 12 moves axially between upper and lower radially extending steps inside the cartridge assembly 11. Major and minor outer cylindrical surfaces of the piston 33 form slidable seals against the internal bores of the fixed parts of the cartridge assembly 11. In addition, major and minor outer cylindrical surfaces of the pilot 36 form slidable seals against the internal bores of piston 33, pilot bushing 34, and poppet 31. At the lower end of the poppet assembly 12 is a poppet 31 that moves toward and away from a poppet seat 13 to close or open the pulse valve in response to changing pressure conditions within the pulse valve and changes in the path of fluid communication within the pulse valve caused by the moving pilot 36. The poppet assembly 12 and cartridge assembly 11 may comprise several pieces to facilitate efficient and low cost manufacturing of the pulse valve, generally as described in U.S. Pat. No. 8,528,649.

FIG. 1B shows the tool in the locked open configuration. The pilot 36 is shown in its lower position, and the poppet assembly 12 is in its upper position with poppet 31 away from poppet seat 13 so the passage of flow through the tool is unobstructed. In this open position, fluid flow is not obstructed and moves from inlet passage A through fluid passages n, h, D, E, and flow restriction G to outlet passage H.

FIGS. 3B and 3C show longitudinal cross-section views of the upper manifold assembly 1, which is disposed within cartridge assembly 11. Upper manifold assembly 1 contains the upper manifold 18 (which also comprises the upper portion of cartridge assembly 11), slidable seal 42, set screws 43, and lock assembly 2 (shown in FIG. 4B). Lock assembly 2 is constrained in movement by shear pins 44. Set screws 43 retain shear pins 44 and form a seal to upper manifold 18. The shear pins may instead be any of one or more shear devices, such as shear screws made from a material of known shear strength, such as a bronze alloy. The shear pins are chosen to be strong enough to restrain the slidable components against the full variety of inertial forces (accelerations and vibrations) during handling and the normal downhole operations such as milling. The shear pins are also designed to allow actuation when the requisite number of balls are dropped into the workstring and pumped to the tool. Lock assembly 2 acts to prevent pilot 36 from shifting to its upper position, which as described in U.S. Pat. No. 8,528,649. The pilot 36 being in its lower position causes poppet assembly 12 to move to its upper position when fluid flows though the tool. In this configuration, the pulse valve is open and allows fluid to pass relatively unobstructed through the tool.

As seen in FIG. 4B, the lock assembly 2 comprises ball catcher 3, pin holder 4, stop rod 5, shear pin 45, capture nut 6, retaining ring 7, bumper 8, and retaining ring 9. Retaining ring 9 prevents bumper 8 from falling off of stop rod 5. Stop rod 5 is disposed coaxially inside of a cavity Q within the pin holder 4 and is also restrained axially by shear pin 45. The bottom of the stop rod has an enlarged section that engages pilot 36 inside of poppet assembly 12. As shown in FIG. 3B, the slidable seal 42 prevents leakage from the upper end of upper manifold 18 and the interior spaces of cartridge assembly 11.

It is common for well service fluids to contain particulate contamination such as sand, fragments of iron oxide, and other intentionally added particles. An annular cavity B is formed between the upper portion of upper manifold 18 and pin holder 4 and ball catcher 3. Passages j are provided to allow debris to pass through cavity B and prevent it from accumulating during operation.

FIG. 5B shows four balls 41 in transit to the four ball seats m in ball catcher 3. In some embodiments, objects other than balls may be used. For example, this may include darts with a dart seat, or another obstruction object with an appropriate seat. In other embodiments, ball seat m may be configured to seat one or more balls. These balls are commonly fabricated from hard polymer (plastic), polymer-fiber composite, or steel. Balls can be inserted into the workstring and pumped to the bottom hole assembly (BHA) using commonly available well site equipment. The passages n leading to ball seats m allow fluid flow to pass through and are designed in such a way that each ball will arrive at a ball seat and not get trapped in any upstream pocket nor be prevented from reaching a ball seat by the position between the balls already seated and the passages n. This design feature could readily be understood by persons knowledgeable in the art of designing multi-ball actuated mechanisms. If objects other than balls are used engage a seat and restrict flow downstream, the objects would have to be designed such that they would not be prevented from reaching the seat by becoming trapped in any upstream pocket. Similarly, the objects would have to be designed to appropriately restrict fluid flow once they were engaged in the seat.

FIG. 6B shows the assembly after the balls 41 have landed in the ball seats m. The upper end of ball catcher 3 and the balls 41 then block fluid flow to flow-through passages h. A slidable clearance seal is created between ball catcher 3, clamp nut 14, and upper manifold 18, as shown in FIG. 1B. Because fluid continues to be pumped into the fixed volume of the supply tubing, and because the outlet at ball catcher 3 is obstructed by the seated balls 41, pressure builds up in passage A and the areas upstream of the tool. At high fluid flow rates, the balls 41 can seat very rapidly, abruptly stopping the flow below ball seat 3 and creating a water hammer pressure pulse which adds to the pressure increase. Also at this time, pressure falls in passage h and in every other passage downstream of the obstruction. When the force due to pressure differential applied to upper end of ball catcher 3 and across the balls 41 reaches the shear strength of shear pins 44, the shear pins 44 shear and the lock assembly 2 is allowed to slide axially and accelerate rapidly downward. Because the bumper 8 is in proximal contact with pilot 36 and the poppet 31 is in proximal contact with the pilot 36, the poppet assembly 12 is caused to slide axially downward along with lock assembly 2. The shorn shear pins 44 are shown in FIG. 7B.

At this point, if force due to pressure differential acting on the upper end of the ball catcher and balls and acting against the inertia of all the slidable components of the tool exceeds the shear strength of shear pin 45, then shear pin 45 will shear and allow the components of lock assembly 2 to slide to their final positions and allow the pulse valve to actuate. If this force is lower than the shear strength of shear pin 45, the lock assembly and poppet assembly will move together to the location shown in FIG. 7B.

FIG. 7B shows lock assembly 2 and poppet assembly 12 moved downward to the lower position of poppet assembly 12. At this point, poppet assembly 12 is prevented from moving forward by contact between poppet seat 13 and lower end of poppet 31. FIG. 7C shows the shear pin 45 intact and not sheared. Flow passages h remain blocked by the balls and the ball catcher and pressure in passage A remains high and increases due to fluid being continuously pumped into the fixed volume of the workstring. When the force due to pressure applied to upper end of the ball catcher and balls reaches the shear strength of shear pin 45, the pin shears and allows all the slidable components to move freely to the full extent of their travel.

FIG. 8B shows the ball catcher moved to its lower position, after both shear pins 44 and shear pin 45 have been shorn. This position is reached when a radially extending step on the ball catcher and the upper manifold 18 come into contact. This allows fluid to flow through the tool again, but now poppet assembly 12 is allowed to begin moving axially through its normal cycle of motions causing the pulse valve, which is downstream of the poppet assembly 12, to operate. The arrangement of ports and the principle of operation of the moving parts may be similar to those described in U.S. Pat. Nos. 7,139,219 or 8,528,649. In the configuration shown in FIG. 8B, the pulse valve is closed and an effective seal is created between poppet 31 and poppet seat 13. Fluid upstream of the poppet seat is at high pressure and fluid downstream of the poppet seat is at low pressure. This pressure differential acts on the annular area between D3 and D4 of piston 33 (shown in FIG. 2B) and creates a large force that causes the piston 33 and the other components of the poppet assembly 12 to slide axially upward and open the pulse valve. The pilot 36, having been in proximal contact with bumper 8, causes the bumper, retaining ring 9, and stop rod 5 to slide upward as well. As the stop rod 5 enters cavity Q within pin holder 4 and ball catcher 3, the displaced volume of fluid of the stop rod 5 exits cavity Q through a longitudinal groove k in the stop rod 5 as shown in FIG. 1C.

With the pulse valve open, pressurized fluid flows through passages h, D, E, flow restriction G, and outlet passage H. The piston 33 reaches its upper position when a radially extending step on the piston 33 reaches the lower surface of the upper stop ring 20. In this configuration the flow passages are reconfigured. Pressure differential then acts on annular area between D1 and D2 (shown in FIG. 2B) and causes the pilot 36 to shift toward its upper position. The bumper 8, still in contact with the pilot, continues to slide upward, carrying the stop rod 5 and retaining ring 9 with it.

FIG. 9B shows that the pilot 36 has moved to its upper position. The upper position of the pilot 36 is reached when a radially extending step on the pilot 36 comes into contact with the lower end of the pilot bushing 34. This event is quite rapid, and the stop rod 5, bumper 8, and retaining ring 9 have significant upward momentum, which causes them to continue sliding upward. The upper position of the stop rod 5 is reached when a radially extending step on the stop rod 5 and the lower end of retainer nut 6 come into contact. In this position, retaining ring 7, being loosely captured between the pin holder 4 and retainer nut 6, engages a radial groove p in the stop rod 5 that prevents the stop rod 5 from leaving this position. Retaining ring 7 constrains the stop rod 5 such that the pilot 36 and bumper 8 no longer come into contact, leaving the pulse valve to cycle normally. The actuation mechanism has, in this configuration, reached its final operation and has no more interaction with the pulse valve.

Once the actuation mechanism as described above has been actuated, the poppet assembly 12 is used to create a water hammer effect. FIGS. 9B, 10B, 11B, and 12B illustrate four stages of the repeating cycle of poppet assembly 12 and pilot 36. The arrangement of ports and the principle of operation of the moving parts of the poppet assembly 12 may be similar to those described in U.S. Pat. Nos. 7,139,219 or 8,528,649, producing a pressure pulse each time that the poppet 31 closes the pulse valve, stopping fluid flow through the outlet passage. In this way, the actuation mechanism provides the ability to control when to activate the water hammer valve.

In another embodiment of the actuation mechanism, shear pins 44 are omitted and pressure forces are employed to restrain the movement of lock assembly 2. Seal friction force due to slidable seal 42 engaging pin holder 4 aids in restraining the lock assembly against inertial forces (accelerations and vibrations) experienced during handling and during normal downhole operations such as milling. As in the embodiment described above, shear pin 45 restrains stop rod 5 from moving axially within pin holder 4. This embodiment is similarly actuated by the dropping of one or more balls 41 into ball seat 3, as shown in FIGS. 5B and 6B. Figures that effectively show this embodiment are FIGS. 1A, 1B, 2A, 2B, 3C, 4A, 4B, 7C, and FIGS. 8 through 12.

The pressure forces that restrain lock assembly 2 can be described as follows. Minor diameter D5 forms a piston area A1 within slidable seal 42. Diameter D5, shown in FIG. 3B, is chosen such that piston area A1 is larger than the annular area J between major diameter D1 and minor diameter D2 of pilot 36. In addition, D5 is chosen such that piston area A1 is smaller than annular area between major diameter D3 and minor diameter D4 of piston 33. The pressure in annular passage D is very nearly equal to (slightly less than) the pressure in passage A, so the downward force on the pilot due to the pressure acting on pin holder 4 is larger than the upward force acting on the pilot in annular area J due to pressure in passage D applied through passages r and q, so the pilot stays in its lower position. In addition, the upward force acting on poppet assembly 12 is larger than the downward force acting on pin holder 4 so the lock assembly and pilot assembly stay in their upper positions until the required number of balls are dropped.

Other release mechanisms may be employed. For example, as an alternative to using shear pins, or in combination with shear pins, a spring-dog detent mechanism may be used.

In yet another embodiment of the actuation mechanism, shown in FIGS. 13A-15B, a spring-loaded latch-detent mechanism (hereafter referred to as the “latch mechanism”) is employed to restrict axial movement of the pilot to initially prevent the water hammer valve from operating. The upper manifold assembly 50 containing the latch mechanism, shown in FIG. 14B in the latched state, shows ball catcher 3 threadably engaged with pin holder 53 and coaxially disposed within upper manifold 18. Circumferential groove S is formed near the upper end of stop rod 5, which is coaxially disposed within pin holder 53. A detent R is formed within upper manifold 18. A tee pin 52 extends through a hole that transversely crosses through pin holder 53, engaging circumferential groove S, and engaging detent R. A strong spring 54, preferably one or more conical disk springs, known as a Bellville washers, provides a force that holds tee pin 52 into detent R and in so doing, restrains pin holder 53 and stop rod 5 from sliding axially. A collet-type high-deflection spring 51 adds to the force provided by the strong spring 54 and is employed after the latch is released. Bumper 8 is coaxially mounted over the lower end of stop rod 5 and is axially retained to the stop rod by retaining ring 9. Retaining nut 7 threadably engages pin holder 53. The retaining nut together with high deflection spring 51 prevent tee pin 52 from moving axially with respect to the pin holder.

It should be noted that the latch mechanism comprising tee pin 52, strong spring 54, high deflection spring 51, and detent R may be one or more, preferably four, instances of said items, as can be seen in FIG. 14C. Various spring configurations, such as leaf springs or coiled springs, may be employed it achieve the same function. In addition, various shapes of the tee pins may be employed in different areas, such as circular in the area where it crosses through holes in pin holder 53 and engages groove S and rectangular in the area where it engages detent R.

As with previously described embodiments, the stop rod 5 and bumper 8, while held in the locked position by the tee pins 52, restricts the axial movement of pilot 36 to its lower position and prevents water hammer valve from operating. When balls 41 are pumped to the tool, and the pressure force acting on the ball catcher exceeds the latch release force, the slidable components of the tool will begin move axially. Those skilled in the art of common mechanisms such as latches will readily understand that FIG. 15B shows the slidable components contained in the upper manifold assembly in their final position, similar to that of FIG. 9B. With the upper manifold assembly 50 components in this final position, the movement of the pilot 36 is no longer restricted and the water hammer valve is free to operate.

Other configurations of a ball seat, piston, release mechanism and trap mechanism may be possible, and the configurations shown herein are not meant to be limiting. Although the concepts disclosed herein have been described in connection with the preferred form of practicing them and modifications thereto, those of ordinary skill in the art will understand that many other modifications can be made thereto. Accordingly, it is not intended that the scope of these concepts in any way be limited by the above description.

Claims

1. A flow-actuated valve comprising:

a housing with an inlet and an outlet, wherein the flow-actuated valve is configured to periodically actuate and at least partially interrupt fluid flow through the housing; and

a releasable lock configured to initially prevent actuation of the flow-actuated valve, wherein the releasable lock is released by increasing the differential pressure through flow passages in the releasable lock.

2. The flow-actuated valve of claim 1, wherein the releasable lock is released by increasing the differential pressure through flow passages in the releasable lock until the differential pressure exceeds a threshold.

3. The flow-actuated valve of claim 1, wherein the flow passages in the releasable lock include one or more flow restrictions wherein the differential pressure is increased by increasing a fluid flow rate though the flow passages.

4. The flow-actuated valve of claim 1, wherein the releasable lock comprises one or more shear pins that initially prevent actuation of the flow-actuated valve.

5. The flow-actuated valve of claim 1, wherein the releasable lock comprises a spring-loaded detent that initially prevents actuation of the flow-actuated valve.

6. The flow-actuated valve of claim 1, wherein the releasable lock comprises a friction detent that initially prevents actuation of the flow-actuated valve.

7. A flow-actuated valve comprising:

a housing with an inlet and an outlet, wherein the flow-actuated valve is configured to periodically actuate and at least partially interrupt fluid flow through the housing; and

a releasable lock configured to initially prevent actuation of the flow-actuated valve,

wherein the releasable lock is released by increasing the differential pressure through flow passages in the releasable lock, wherein increasing the differential pressure causes the releasable lock to move from a first position to a second position.

8. The flow-actuated valve of claim 7, wherein the flow passages of the releasable lock are open when the releasable lock is in the first position, wherein the flow passages are at least partially closed when the releasable lock is shifting from first position to second position, wherein the flow passages are open when the releasable lock is in the second position.

9. The flow-actuated valve of claim 7, wherein the differential pressure is increased by seating one or more obstruction objects in the flow passages.

10. The flow-actuated valve of claim 9, wherein the one or more obstruction objects are one or more balls.

11. The flow-actuated valve of claim 9, wherein the one or more obstruction objects are one or more darts.

12. The flow-actuated valve of claim 7, wherein the releasable lock is released by increasing the differential pressure through flow passages in the releasable lock until the differential pressure exceeds a threshold.

13. The flow-actuated valve of claim 7, wherein the flow passages in the releasable lock include one or more flow restrictions wherein the differential pressure is increased by increasing a fluid flow rate though the flow passages.

14. The flow-actuated valve of claim 7, wherein the releasable lock comprises one or more shear pins that initially prevent actuation of the flow-actuated valve.

15. The flow actuated valve of claim 7, wherein the releasable lock comprises a spring-loaded detent that initially prevents actuation of the flow-actuated valve.

16. The flow-actuated valve of claim 7, further comprising:

a pilot, the pilot initially being held in a first position by the releasable lock, the pilot able to move axially into a second position when not being held by the releasable lock; and

a poppet, wherein axial movement of the pilot from the first position to the second position causes the poppet to at least partially close, and axial movement of the pilot back into the first position causes the poppet to open,

wherein the pilot is released from the first position after the releasable lock is released.

17. The flow-actuated valve of claim 16, wherein axial movement of the poppet into the at least partially closed position causes the pilot to move into the first position.

18. A method of operating a flow-actuated valve, comprising:

restricting actuation of a valve using a releasable lock, the releasable lock comprising flow passages to permit fluid flow;

increasing the differential pressure through the flow passages in the releasable lock;

releasing the releasable lock, wherein the releasable lock is released when the differential pressure through the flow passages in the releasable lock is increased above a threshold pressure; and

actuating the valve periodically when the releasable lock has released.

19. The method of claim 18, wherein the releasable lock comprises one or more shear pins that initially restrict actuation of the valve.

20. The method of claim 18, wherein the releasable lock comprises a spring-loaded detent that initially restricts actuation of the valve.

21. The method of claim 18, wherein the releasable lock comprises a friction detent that initially restricts actuation of the valve.

22. The method of claim 18, wherein the differential pressure through the flow passages is increased by receiving one or more released obstruction objects into a seat in the flow passages.

23. The method of claim 22, wherein the obstruction objects are balls.

24. The method of claim 22, wherein the obstruction object are darts.