Bypass valve

Abstract

A method and apparatus for controlling fluid flow through a drill string includes a housing having an axis, a radial wall with a bore extending axially therethrough, and an aperture formed in the radial wall. The aperture is in fluid communication with the bore. A piston is located inside the housing and has an orifice configured to permit axial fluid flow through the housing. The spring axially biases the piston to a closed position.

Claims

1. A fluid pressure actuated diverter valve apparatus for controlling fluid flow to a mud motor for a milling tool supported on a tubular string, comprising: a housing forming a part of the tubular string and further comprising an inlet, a straight through outlet and at least one lateral wall port; a piston reciprocally mounted within said housing; the piston including a top end, at least one internal passage disposed through the piston downwardly from the top end through which fluid is permitted to flow through the piston to the mud motor without obstruction during a milling operation; a lateral flow passage which extends between the top end and a lateral outlet within the piston; wherein the piston is reciprocated from an upper position and a lower position within the housing by increasing flow through the piston to maintain a predetermined flow to the mud motor by circulating excess flow into said housing through said lateral flow passage; and wherein at least a portion of the lateral flow passage is maintained at a position within the housing above the lateral wall port when the piston is in the lower position.

2. The apparatus of claim 1, wherein: the lateral flow passage includes a plurality of split flow paths deviating from the orifice.

3. The apparatus of claim 2, wherein: at least one of the split flow paths remains in fluid communication through the piston to permit flow from a flow path above the piston to a flow path below the piston.

4. The apparatus of claim 3, wherein: at least one of the split flow paths is obstructed when the piston is in its upper position from permitting fluid communication through the piston and through the lateral wall port in the housing.

5. The apparatus of claim 4, wherein: at least one of the split flow paths is in fluid communication through the piston when the piston is in its lower position to permit flow from the flow path above the piston through the lateral wall port to an annulus outside of the housing.

6. The apparatus of claim 1, wherein: said lateral flow passage further comprises a crescent shaped inlet at said top end of said piston.

7. The apparatus of claim 1, wherein: said housing defines an interior plenum about said at least one lateral wall port; said lateral flow passage comprising multiple outlets selectively axially aligned with said plenum.

8. The apparatus of claim 7, wherein: said at least one lateral wall port comprises multiple circumferentially spaced wall ports communicating with said interior plenum; at least one of said multiple outlets is circumferentially misaligned with at least one said wall port.

9. The apparatus of claim 7, wherein: said lateral flow passage extending substantially parallel to said straight through passage until turning radially outwardly to orient said multiple outlets radially toward said plenum.

10. The apparatus of claim 1, wherein: said multiple outlets further comprise hardened nozzles with outlets oriented radially into said plenum.

11. The apparatus of claim 1, wherein: said at least one lateral wall port comprises a plurality of spaced wall ports; said lateral flow passage comprising multiple outlets each selectively aligned with a respective wall port.

12. The apparatus of claim 1, wherein: said lateral flow passage comprising multiple outlets each angularly oriented toward a downhole end of said piston.

13. The apparatus of claim 1, wherein: said housing further comprising a hardened ring to protect at least one seal around said piston from erosion of fluid flowing past one or more outlets from said lateral flow passage.

14. The apparatus of claim 1, wherein: said internal passage and said lateral flow passage extend axially from said top end of said piston with said lateral flow passage comprising a crescent shape cross section with multiple outlets radially extending outlets adjacent said outer periphery of said piston.

15. The apparatus of claim 14, wherein: said piston is fabricated with an additive manufacturing process.

16. The apparatus of claim 1, wherein: said piston comprises a clearance fit to said housing for damping high frequency movement of said piston resulting from fluid flow.

17. The apparatus of claim 16, wherein: said internal passage is unrestricted.

18. The apparatus of claim 1, wherein: said flow generated force is created in said internal passage.

19. The apparatus of claim 1, wherein: the shape of at least one of said passages is round, oval or crescent.

20. The apparatus of claim 1 further comprising: an orifice defined within the top end of the piston from which the internal passage and the lateral flow passage both extend.

21. The apparatus of claim 1 further comprising: a separate axial end opening for the lateral flow passage at the top end of the piston.

22. A flow control method for a borehole tool, comprising: providing a housing further comprising an inlet, a straight through outlet and at least one lateral wall port, the housing further having end connections for attaching to a tubular string to position a borehole tool in a borehole; additively manufacturing a piston in said housing selectively covering said wall port, said piston comprising an internal passage extending downwardly from an orifice proximate a top end of the piston in flow communication with said straight through outlet and a lateral flow passage beginning adjacent said top end to a circulation outlet and extending to an outer periphery of said piston, said circulation outlet movable into aligned or misaligned positions with respect to said at least one lateral wall port responsive to flow generated force in said straight through passage opposing a bias force on said piston; maintaining a predetermined flow to the borehole tool by circulating excess flow into said housing through said lateral flow passage, at least a portion of the lateral flow passage remaining above the lateral wall port as said excess flow is circulated.

23. The method of claim 22, comprising: maintaining said lateral flow passage circulation outlet no lower than said at least one wall port.

24. The method of claim 22, comprising: shaping said lateral flow passage in a crescent shape in an axial orientation with multiple openings as said circulation outlet.

25. The method of claim 24, comprising: making said at least one wall port multiple wall ports; directing said multiple openings into a plenum defined by said housing and placing nozzles in said openings to direct flow into said plenum and through said multiple wall ports.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic section view in the full bypass open position;

(2) FIG. 1A is a schematic view of portions of the tubular string which include a mud motor and milling tool.

(3) FIG. 2 is a section view in the flow through position with no bypass flow;

(4) FIG. 3 is the view of FIG. 2 with full bypass flow open;

(5) FIG. 4 is an enlarged view of FIG. 3;

(6) FIG. 5 is an external view of the piston showing an integrated exit port;

(7) FIG. 6 is a section view through the piston of FIG. 5;

(8) FIG. 7 is a section view of FIG. 4 showing the inlet to the piston;

(9) FIG. 8 is another section view below FIG. 7 at the annular diffuser chamber level;

(10) FIG. 9 is another section below FIG. 8 at the housing port level;

(11) FIG. 10 is an external view of the piston of FIGS. 2 and 3;

(12) FIG. 11 is a section view through the piston of FIG. 10;

(13) FIG. 12 is an end view through the piston of FIG. 6;

(14) FIG. 13 is a section view through the piston of FIG. 6 at the top of the outlet from the piston;

(15) FIG. 14 is a section view of an assembly where the piston is not made with additive manufacturing in the bypass open position;

(16) FIG. 15 is the view of FIG. 14 with the bypass closed position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(17) Referring to FIG. 1, a housing 10 is part of a tubular string that is not shown. At the lower end 12 there is a mud motor 11 that operates a tool 13 such as a drill bit, for example, as depicted in FIG. 1A. Above the upper end 14 a string extends to a pump that is not shown to deliver pressurized fluid to the mud motor which is typically a progressing cavity pump also referred to as a mud motor, such as a Moineau style pump. The mud motor 11 needs a steady predetermined flow rate that is maintained through the use of a translating piston 16 that has an orifice 18 and a schematically illustrated combination travel stop and rotational lock 20. A biasing string 22 offers resistance to axial displacement of the piston 16 created by the force to get the predetermined flow rate through orifice 18. Below a predetermined flow rate determined by the size of the orifice 18 and the strength of the spring 22 the piston 16 is located higher than shown in FIG. 1 so that the lateral passage 24 leading to the outlet 26 is closed because it is up against the inside wall of the piston 16 with outlet 26 between spaced seals 30 and 32. Alignment between piston opening 26 and annular port 34 is important to reduce erosion and is achieved when end 35 of extension tube 36 contacts travel stop 37 in housing 10. Flow through orifice 18 travels through internal passage 19 to operate the mud motor 11.

(18) Lateral passage 19 is shown as being crescent shaped. The reason it is preferably crescent shaped is to provide maximum flow area around the internal passage 19. There is a gradual transition from the crescent shape to outlet to minimize erosion. This could also be accomplished by making both passage 19 and 24 crescent shaped, or making passage 19 crescent shaped and passage 24 circular. Another possibility would be for one of both of the passages 19 and 24 to be oval instead of circular.

(19) Life of seals 30 and 32 can be reduced if piston 16 rapidly oscillates in housing 10 because of inconsistent flow rates through the piston. Seal damage can be reduced by controlling how quickly fluid flows in and out of chamber 41 between extension tube 36 and housing 10. By creating a tight radial clearance 39 between extension tube 36 and housing 10 high frequency movement of piston 16 is damped because fluid entering and leaving chamber 41 is restricted by the tight clearance. Passage 24 can be totally independent of passage 18 to the top of piston 16 or intersect passage 18 near the top end of the piston 16 so that incremental flow as piston 16 moves goes through passage 24 as ports 26 and 34 come into alignment. At flow rates above a predetermined level, typically over 4 barrels a minute (for a 2 motor with higher flow rates contemplated for larger motors), displacement of piston 16 begins until travel stop and rotational lock 20 halts axial movement with the outlet 26 aligned with wall opening 34. Although a single passage 24 leading to an opening 26 that ultimately aligns with opening 34 is illustrated, more than one path out of the housing 10 is contemplated as will be later described. The orifice 18 may be a removable disc or a carbide nozzle with a passage through it so that it can be replaced if it wears or it may be integral with passage 19 through the piston 16 that can be lined with a removable sleeve or unlined. In any event, the orifice remains higher than the wall opening 34 even in the full bypass flow out of port 34 into the surrounding annular space. While the recirculation flow out opening or openings 34 is variable the flow to the mud motor that is not shown remains constant. The flow straight through to the mud motor and laterally out the housing 10 both go through the piston 16. Preferably, the total flow rate should be increased so that if there is to be bypass flow out port or ports 34 the axial travel of the piston 16 should be at the stop represented by 20 so that openings 26 line up with openings 34. Variations of the FIG. 1 schematic design will be described below.

(20) FIG. 2 shows a layout of the schematic design of FIG. 1. The housing 10 is multicomponent between ends 12 and 14 Piston 16 has an extension tube 36 with a flange 38 against which spring 22 applies an uphole force. Multiple ports 34 communicate with an annular plenum 40 that is closed off by piston 16 and seals 30 and 32. Seal 32 is on piston 16 while seal 30 is fixed in the housing 10 near the upper end 14. Passage 19 has a removable orifice 42 held with a removable retainer 44. Retainer 44 can be threaded or otherwise attached to hold orifice 42 piston 16. The use of an orifice or any restriction in passage 19 is optional. Hardened nozzles 46 communicate with plenum 40 and the combined flow into plenum 40 exits housing 10 through ports 34. Hardened wear ring 48 protects seal 30 and housing 10 from erosive action of high velocity flow, particularly when piston 16 has not shifted fully in to the wide open bypass position of FIG. 3.

(21) FIGS. 5 and 6 show recirculation passage 24 terminating in an outlet 52 that has formed downhole taper 54 and a rounded uphole end 56. An internal deflector ramp 58 can be provided. Those skilled in the art will appreciate that the various configurations described with the exception of FIGS. 14 and 15 can only economically be fabricated with the process of additive manufacturing. While FIGS. 5 and 6 show a single piston outlet port 26 there can be multiple ports circumferentially offset such that the passage 24 has a crescent shaped entrance as shown in FIGS. 7 and 12. If nozzles 46 are used in the FIGS. 5 and 6 design they can align with respective openings 26 of the piston 16 for insertion and securing such as by brazing or with adhesive or other known ways of fixation. FIG. 8 shows a section view through piston 16 at the location of the nozzles 46. FIG. 9 shows another section view a bit lower down illustrating the plenum 40 leading to multiple outlets 34 where some nozzles are out of alignment with ports 34 but others can be in radial alignment with an opening 34. Four openings 34 are shown and three nozzles 46 but different quantities of each can be used. The additive machining process allows this and the use of the plenum 40 volume allows all the outlets of the nozzles 46 to reach an outlet port 34 even if the flow direction is reoriented one or more times to find a path to exit for recirculation flow while avoiding passing through the mud motor.

(22) FIG. 10 is an external view of piston 16 in FIG. 2. FIG. 11 is a cross section view of FIG. 10. FIGS. 8 and 9 show section views of the piston 16 corresponding to the embodiment of FIGS. 10 and 11. FIGS. 12 and 13 correspond to the variation shown in FIGS. 5 and 6.

(23) FIGS. 14 and 15 show the limitations of fabrication of piston 16 using intersecting bores to construct passage 24 to opening 26. Here depending on the size of the piston 16 only a single drilled bore 24 may be possible that is intersected at right angles with another bore to create the exit port 26. On the other hand when using additive manufacturing internal passageways can be created that cannot be made with other fabrication techniques currently known or even using known casting or molding techniques. A crescent shaped bypass passage 24 can be created with multiple outlets into which a nozzle can be secured. The surrounding housing 10 can define a plenum 40 that links outlets of multiple nozzles 46 for ultimate flow exit through openings 34 in housing 10 for recirculation bypassing the mud motor or other tool that is in the bottom hole assembly that is not shown.

(24) The various described embodiments split flow between straight through and recirculation so that as the flow increases there are two distinct paths and recirculated flow avoids the straight through flow restricting path. While all flow goes through the piston, the flow is split within the piston in discrete straight through and recirculating paths. The piston with these discrete paths is additively manufactured to allow multiple exit nozzles for the recirculating path that can discharge into aligned outlet ports in the surrounding housing or into a plenum between the piston and the outer housing where flow can exit out radially or can be redirected at least once to a nearby housing exit port. The discrete recirculation path can be crescent shaped to maximize the number of outlets particularly in the smaller sizes.

(25) The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: