Pulser Cycle Sweep Method and Device

Abstract

A servo valve in a servo pulser used to restrict flow to a larger main valve includes external stops on a housing to define rotational starting/stopping points and sweep zones for a servo rotor having digits for contacting the stops. The digits extend longitudinally away from the servo valve seat and extend into the sweep zones. Interaction between the stops and the digits in the sweep zones limit rotation of the rotor to a swept arc between the stops. The servo pulser rotor oscillates between stopping points in alternating clockwise/counterclockwise sweeps. Each sweep in a given direction creates one full pulse: closed, open, and closed. The servo pulser carries out a feedback/decision loop between hydraulic pulses (and sweeps) that receives information on one or more previous pulses and calculates how fast or slow it should drive the servo rotor for the current pulse.

Claims

1. A servo pulser for a mud pulse telemetry MWD system, comprising: a servo rotor; and a valve seat; and a housing around the rotor, the housing forming at least one arcuate sweep zone rotationally fixed relative to the valve seat; and the servo rotor comprising laterally-extending arms; and at least one digit extending longitudinally away from the seat and into one of said at least one sweep zone.

2. The servo pulser of claim 1, the housing comprising at least one stop on the interior of said housing; and the at least one sweep zone comprising at least one clockwise stopping point and at least one counter-clockwise stopping point.

3. The servo pulser of claim 2, the housing comprising two stops; and one of the stops forming the at least one clockwise stopping point and other of the stops forming the at least one counter-clockwise stopping point.

4. The servo pulser of claim 3, the housing comprising two arcuate sweep zones rotationally fixed relative to the valve seat; and each of the stops forming a clockwise stopping point and a counter-clockwise stopping point.

5. The servo pulser of claim 2, the servo rotor having a permitted sweep arc defined by mechanical interaction between at least one stop and the at least one digit.

6. The servo pulser of claim 1, the housing forming two arcuate sweep zones rotationally fixed relative to the valve seat; and the servo rotor comprising two digits extending longitudinally away from the seat, each of said digits extending into one each of the two sweep zones.

7. The servo pulser of claim 6, the housing comprising two stops; and each of the stops forming a clockwise stopping point and a counter-clockwise stopping point.

8. The servo pulser of claim 1, the servo rotor comprising four laterally-extending arms; each of said arms comprising a servo tip extending longitudinally toward the seat; and two digits extending longitudinally away from the seat.

9. The servo pulser of claim 1, the servo rotor having a permitted sweep arc defined by mechanical interaction between the housing and the at least one digit.

10. The servo pulser of claim 9, the sweep arc being at or around 90 degrees.

11. The servo pulser of claim 1, the valve seat comprising servo holes; and travel zones between the servo holes; the travel zones not permitting fluid flow therethrough; and the travel zones extending about 20-25 degrees.

12. A method of controlling a servo pulser for a mud pulse telemetry MWD system, comprising: rotating a servo rotor; the servo rotor comprising laterally-extending arms; and at least one digit extending longitudinally away from a valve seat and into at least one arcuate one sweep zone; and the at least one sweep zone formed by a housing around the rotor and rotationally fixed relative to the valve seat.

13. The method of claim 12, the at least one sweep zone comprising at least one clockwise stopping point and at least one counter-clockwise stopping point; and the mechanically interacting step occurring at the stopping points.

14. The method of claim 12, the rotating step comprising rotating the servo rotor within a permitted sweep arc defined by mechanically interacting the at least one digit and the housing.

15. The method of claim 12, further comprising defining a sweep arc of the rotating step by mechanically interacting the at least one digit and the housing.

16. The servo pulser of claim 15, the sweep arc being at or around 90 degrees.

17. The method of claim 12, the rotating step comprising rotating the servo rotor between stopping points and through travel zones between servo holes on the servo seat; the travel zones not permitting fluid flow therethrough; and the travel zones are about 20-25 degrees in extent.

18. The method of claim 12, the rotating step comprising creating a full pulse during a single sweep of the servo rotor in a given direction.

19. The method of claim 18, the single sweep of the servo rotor beginning and ending with the mechanical interaction between the at least one digit and the housing.

20. The method of claim 18, the rotating step further comprising reversing the direction of the rotation of the servo rotor; and then creating another full pulse during another single sweep of the servo rotor.

21. The method of claim 12, the rotating step comprising rotating the servo rotor between stopping points and through travel zones between servo holes on the servo seat; the travel zones not permitting fluid flow therethrough; and the travel zones are about 20-25 degrees in extent.

22. The method of claim 12, the rotating step comprising the servo rotor starting such that servo tips on said laterally-extending arms fully close servo holes on said servo seat; and then continuing rotating the servo rotor continuously in one direction first to rotate the servo tips to fully open the servo holes, and then to rotate the servo tips to close the servo holes.

23. The method of claim 22, the continuing rotating step further comprising braking the rotation of the servo rotor while the servo holes are fully open.

24. The method of claim 12, the rotating step comprising the servo rotor starting such that servo tips on said laterally-extending arms fully close servo holes on said servo seat; then rotating the servo rotor in one direction to rotate the servo tips to fully open the servo holes; then stopping the servo rotor such that the servo tips rest in travel zones between the servo holes; and then rotating the servo rotor in the same direction to rotate the servo tips to close the servo holes.

25. The method of claim 12, further comprising executing a feedback loop between pulses to determine the desired velocity profile for driving the servo rotor.

26. The method of claim 25, the feedback loop comprising comparing a last-pulse sweep time to a last-pulse digital pulse width.

27. The method of claim 26, the feedback loop further comprising commanding the servo rotor to move continuously between a starting point and a stopping point.

28. The method of claim 26, the feedback loop further comprising commanding the servo rotor to move from a starting point to an intermediate stop in a travel zone; then checking if enough time has elapsed for a desired pulse width; then commanding the servo rotor to move from the intermediate stop to a stopping point.

29. The method of claim 25, further comprising saving the current sweep time and current digital pulse width.

30. A method of controlling a servo pulser for a mud pulse telemetry MWD system, comprising: executing a feedback loop between pulses to determine the desired velocity profile for driving rotation of a servo rotor, the feedback loop comprising comparing a last-pulse sweep time to a last-pulse digital pulse width; saving a current sweep time and a current digital pulse width; and setting the direction of the next pulse for the opposite direction of the current pulse.

31. The method of claim 30, further comprising between the comparing and saving steps, commanding the servo rotor to move continuously between a starting point and a stopping point.

32. The method of claim 30, between the comparing and saving steps, commanding the servo rotor to move from a starting point to an intermediate stop in a travel zone; then checking if enough time has elapsed for a desired pulse width; then commanding the servo rotor to move from the intermediate stop to a stopping point.

33. The method of claim 32, carrying out the checking step again, before commanding the servo rotor to move from the intermediate stop to a stopping point.

34. The method of claim 32, the step of commanding the servo rotor to move from the intermediate stop to a stopping point comprising a deceleration event before reaching the stopping point.

35. A method of pulsing using a servo pulser for a mud pulse telemetry MWD system, comprising: creating a first full pulse by carrying out a first sweep of a servo rotor in a given direction; reversing the direction of the rotation of the servo rotor; and creating a second full pulse by carrying out a second sweep of the servo rotor.

36. The method of claim 35, the servo rotor rotation limited by a permitted sweep arc, the sweep art defined by mechanical interactions.

37. The method of claim 36, defining the sweep arc by mechanically interacting at least one digit extending longitudinally away from a servo seat and a housing.

38. The method of claim 35, the sweep arc being at or around 90 degrees.

39. The method of claim 38, the first sweep of a servo rotor step comprising rotating the servo rotor through travel zones between servo holes on a servo seat; the travel zones not permitting fluid flow therethrough; and the travel zones are about 20-25 degrees in extent.

40. The method of claim 35, further comprising executing a feedback loop between the first pulse and the second pulse to determine the desired velocity profile for driving the servo rotor.

41. The method of claim 40, the feedback loop comprising comparing a last-pulse sweep time to a last-pulse digital pulse width.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0046] FIG. 1A is a representative view of parts of the surface and downhole portions of a drilling rig.

[0047] FIG. 1B is a partial cutaway of the upper portion of the MWD tool as shown in FIG. 1A.

[0048] FIG. 1C shows a front view of portion of a servo pulser showing several sections separated from one another.

[0049] FIG. 2 is a representative view of the various components that together may comprise the downhole portion of an MWD tool.

[0050] FIG. 3A shows a right, front, top, oblique exploded view of a portion of an embodiment of the invention.

[0051] FIG. 3B shows a left, rear, top, oblique exploded view of portion of the embodiment of the invention shown FIG. 3A.

[0052] FIG. 4A shows a right, front, top, oblique view of a servo screen housing of an embodiment of the invention.

[0053] FIG. 4B shows a left elevation of the screen housing in FIG. 4A.

[0054] FIG. 4C shows a section view along line A-A from FIG. 4B.

[0055] FIG. 4D shows a section view along line B-B from FIG. 4C.

[0056] FIG. 5A shows right elevation of a servo seat of an embodiment of the invention.

[0057] FIG. 5B shows a section view along line C-C from FIG. 5A.

[0058] FIG. 6A shows left elevation of a nozzle insert of an embodiment of the invention.

[0059] FIG. 6B shows a section view along line D-D from FIG. 6A.

[0060] FIGS. 7A-E show a series of opening/closing states of the servo pulser as viewed along internal sightline E in FIG. 3A.

[0061] FIGS. 7F-J show a second series of opening/closing states of the servo pulser in the reverse order as in FIGS. 7A-E.

[0062] FIG. 8 shows interrelationships between certain operational statuses and actions of an embodiment of the invention in a first process.

[0063] FIG. 9 shows interrelationships between certain operational statuses and actions of an embodiment of the invention in a second process.

[0064] FIG. 10 shows interrelationships between certain operational statuses and actions of an embodiment of the invention in a third process.

[0065] FIG. 11 shows steps of a process for carrying out an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0066] In one embodiment of the invention, as described in detail below, information of use to the driller is measured at the bottom of a borehole relatively close to the drilling bit and this information is transmitted to the surface using pressure pulses in the fluid circulation loop that manifest as pulses in the surface pressure. The command to initiate the transmission of data may be sent by stopping fluid circulation and allowing the drill string to remain still for a minimum period of time. Upon detection of this command, the downhole tool measures at least one downhole condition, usually an analog signal, and this signal is processed by the downhole tool and readied for transmission to the surface. When the fluid circulation is restarted, the downhole tool waits a predetermined amount of time to allow the fluid flow to stabilize and then begins transmission of the information by repeatedly closing and then opening the pulser valve to generate pressure pulses in the fluid circulation loop. The sequence of pulses sent is encoded into a format that allows the information to be decoded at the surface and the embedded information extracted and displayed.

[0067] Referring now to the drawings and specifically to FIG. 1A, there is generally shown therein a simplified sketch of the apparatus used in the rotary drilling of boreholes 12. A borehole 12 is drilled into the earth using a rotary drilling rig which consists of a derrick 14, drill floor 16, draw works 18, traveling block 20, hook 22, swivel joint 24, kelly joint 26 and rotary table 28. A drill string 30 used to drill the bore well is made up of multiple sections of drill pipe that are secured to the bottom of the kelly joint 26 at the surface and the rotary table 28 is used to rotate the entire drill string 30 while the draw works 18 is used to lower the drill string 30 into the borehole and apply controlled axial compressive loads. The bottom of the drill string 30 is attached to multiple drilling collars 32, which are used to stiffen the bottom of the drill string 30 and add localized weight to aid in the drilling process. A measurement while drilling (MWD) tool 10 is generally depicted attached to the bottom of the drill collars 32 and a drilling bit 34 is attached to the bottom of the MWD tool 10.

[0068] The drilling fluid or “mud” is usually stored in mud pits or mud tanks 36, and is sucked up by a mud pump 38, which then forces the drilling fluid to flow through a surge suppressor 40, then through a kelly hose 42, and through the swivel joint 24 and into the top of the drill string 30. The fluid flows through the drill string 30, through the drill collars 32, through the MWD tool 10, through the drilling bit 34 and its drilling nozzles (not shown). The drilling fluid then returns to the surface by traveling through the annular space 44 between the outer diameter of the drill string 30 and the well bore 12. When the drilling fluid reaches the surface, it is diverted through a mud return line 46 back to the mud tanks 36.

[0069] The pressure required to keep the drilling fluid in circulation is measured by a pressure sensitive transducer 48 on the kelly hose 42. The measured pressure is transmitted as electrical signals through transducer cable 50 to a surface computer 52 which decodes and displays the transmitted information to the driller.

[0070] FIG. 1B shows a partial cutaway of the upper portion of the MWD tool 10 to reveal pulser 62 (main pulser, main valve) connected to servo pulser 64. Both are located within the inner diameter of MWD tool 10. The one end of pulser 62 is connected to servo pulser 64 to create a path for drilling fluid between those components. The other end of pulser 62 is in contact with the internal drilling fluid column 13 within the inner diameter of MWD tool 10.

[0071] FIG. 1C shows servo pulser 64 with the several sections separated from one another for clarity. Servo nozzle housing 102 is hydraulically and mechanically attached to pulser 62 at its first end via female connector 109, and mechanically to a first end of compensator housing 306 at its second end, so that servo shaft 126 and be driven therefrom through keyed end 127 which is permanently attached to servo shaft 126. Second end of compensator housing 306 is mechanically attached via male connector 108 and female connector 109 to a first end of electronics housing 310, and second end of electronics housing 310 is mechanically and electrically attached as part of MWD tool 10. FIG. 2 generally shows a schematic representation of the various components that together make up the downhole portion of an MWD tool. The downhole MWD tool 10 consists of an electrical power source 54 coupled to controller 56. Controller 56 is coupled to sensor package 58 and servo pulser 64. The servo pulser 64 is coupled to a vibration and rotation sensitive switch 60 and a pulser 62.

[0072] FIG. 2 shows one embodiment of the method of the MWD tool. Another embodiment (not depicted) is one in which the vibration and rotation sensitive switch 60 is integrated into the servo pulser 64. Another embodiment (not depicted) is one in which controller 56 is integrated into the servo pulser 64 which is directly connected to sensor package 58.

[0073] Controller 56 in FIG. 2 has the ability to be alerted or informed of the status of the vibration and rotation present in the drill string either by directly communicating to the vibration and rotation sensitive switch 60 or by having this information transmitted through the servo pulser 64. The vibration and rotation sensitive switch 60 can be integrated into the controller 56 and can thereby acquire this information directly.

[0074] Returning to FIG. 1C, and with reference to FIGS. 3A-3B, in an embodiment of the invention, servo nozzle housing 102 includes screen housing 103 and nozzle bulkhead 104, with servo valve 101 within screen housing 103. Screen housing 103 includes fluid inlets 146 in this embodiment, two thereof, spaced about the circumference of screen housing 103, and which are screened by servo screens 147 as a filtering/screen mechanism to restrict large particulate matter as are sometimes present in the drilling fluid 66 from entering into fluid inlets 146. Fluid inlets 146 allow drilling fluid to enter screen housing 103 and be hydraulically connected to/from servo valve 101 via central channel 142, and through valve 101, and via valve 101 to nozzle bulkhead 104 and then on to pulser 62.

[0075] Compensator housing 306 encloses a dual shaft gearbox (not shown) for coupling to and driving servo shaft 126 by drive shaft 326 via keyed end 127, drive shaft 326 being located at a first end of compensator housing 306. The gearbox is attached at its second end to magnetic bulkhead 308 via a shaft through a piston compensator (not shown). Oil fill plugs 304 are provided in compensator housing 306 to permit filling the interior thereof with hydraulic oil for lubrication and pressure compensation, that is, to balance internal oil pressure on gaskets and seals with the exterior fluid pressure. Compensator housing 306 includes a piston compensator exposed to the pressure of the drilling fluid on one upstream side and transmitting that pressure to compress the oil-filled interior of compensator housing 306. Magnetic bulkhead 308 also includes a coupling device (not shown) to transmit torque between to drive shaft 326 (via a dual-shaft gearbox) from electronics housing 310 through the use of a plurality of magnets on compensator housing 306 matched to a plurality of magnets on magnetic coupling 312 of electronics housing 310. That magnetic coupling device drives one end of the dual-shaft gearbox resident inside compensator housing 306, the other end of the dual-shaft gearbox being connected to drive shaft 326.

[0076] Electronics housing 310 includes magnetic coupling 312 at its first end, connected to electric motor 328. Electronics housing 310 includes motor driver 316, and at its second end includes mechanical connections and electrical connection 318. Connection 318 allows servo pulser 64 to be mechanically and electrically connected to controller 56 or electrical power source 54 or in general, to other components that may make up part of MWD tool 10.

[0077] Turning to FIGS. 3A, 3B, and 4A-4D, in an embodiment of the invention, screen housing 103 includes female connectors 109 on each end of body 140, valve section 150 at the end adjacent to nozzle bulkhead 104, and with fluid inlets 146 between valve section 150 and female connector 109 that connects to electronics housing 310. Central channel 142 creates a connecting space down the center of body 140 fluidically connecting fluid inlets 146 to valve section 150. That fluidic connection allows drilling fluid 66 to reach servo valve 101. Central channel 142 also is a space for servo shaft 126 to pass axially toward female connector 109 connected to electronics housing 310 to permit keyed end 127 to be connected to and driven by drive shaft 326.

[0078] Valve section 150 of screen housing 103 contains servo valve 101 positioned within valve section 150, which includes servo seat retainer 153 and dl, with rotor section 151 being more proximal to fluid inlets 146 and between valve seat retainer 153 and fluid inlets 146. Servo valve 101 includes servo rotor 120 and servo seat 170.

[0079] Servo rotor 120 is placed inside rotor section 151 and includes servo shaft 126, with keyed end 127, and rotor arms 122, each having a common axis of rotation 121. Rotor arms 122 are lateral extensions reaching radially off axis of rotation 121 of servo shaft 126. Rotor arms 122 include servo tips 124 attached thereto, e.g. by means of an interference press fit, into tip holes 123 formed on valve seat side 130 of rotor arms 122. Servo tips 124 thus extend axially seat-wise from rotor arms 122 toward servo seat 170 and away from stops 156 and fluid inlets 146 and servo shaft 126. Rotor arms 122 also include digits 125 either formed thereon, or attached thereto, onto opposing stop side 131 thereof. Digits 125 thus extend axially stop-wise from rotor arms 122 away from servo seat 170 and toward stops 156 and fluid inlets 146 and servo shaft 126, and in the opposing direction of servo tips 124. Digits 125 include opposing faces substantially tangent to the directions of rotation, clockwise CW face 133 and counter-clockwise CCW face 134. In this embodiment, there are four rotor arms 122, each with one servo tip 124, but only two digits 125, rotor arms 122 with a digit 125 are separated from one another by another one rotor arm 122 without a digit 125. In addition, dowel pin 129 is also attached to servo shaft 126 on axis of rotation 121, e.g., by means of an interference press fit for fitting into rotor pin hole 179 of servo seat 170.

[0080] Turning to FIGS. 3A, 3B, 4A-4D, and 5A-5B, in an embodiment of the invention, servo seat 170 is set within cylindrical servo seat retainer 153 and includes rotor face 175, facing servo rotor 120, and opposing nozzle face 176. Servo holes 171 pass through servo seat 170 from rotor face 175 to nozzle face 176. Servo seat 170 also includes rotor pin hole 179 at the center thereof on rotor face 175, and keyholes 178 depressed into the outer edge of rotor face 175 for locking into anti-rotation keys 154 of servo seat retainer 153 on the interior of servo screen housing 103. Nozzle face 176 of servo seat 170 includes axially-extending peripheral ring 173. Ring 173 extends axially toward nozzle bulkhead 104. Ring 173 extends from at or about the outer periphery of servo seat 170 to at or about 30% of the radius of ring 173, and is broad enough to occlude a fraction, at or about 50% of the axially-oriented flow area 174 of servo holes 171. Servo holes 171 are circular on rotor face 175, and spaced about symmetrically radially outward of rotor pin hole 179 and inward of the outer edge of servo seat 170. Rotor face 175 includes travel zones 177, being the portions of rotor face 175 not pierced by servo holes 171 and over which servo tips 124 can pass in rotational fashion without occluding servo holes 171. Servo holes 171 extend axially through nozzle face 176 but are roughly semi-circular as viewed axially, being partially occluded by the inner edge of ring 173. Servo holes extend axially past nozzle face 176 and terminate in angled flow redirect 172, which acts to turn the flow of drilling fluid 66 from essentially axial at rotor face 175 to partially radially inwardly beyond nozzle face 176 to direct flow into nozzle insert 112.

[0081] In operation, servo tips 124 are pressed onto rotor face 175 of servo seat 170 and are located radially by guiding dowel pin 129 into rotor pin hole 179. In this manner, servo shaft 126, rotor arms 122, and servo tips 124 are located to the servo seat 170 to allow servo shaft 126 to be rotated relative to servo seat 170 and servo holes 171.

[0082] Servo seat 170 and servo tips 124 are preferably made out of a hard material to provide significant resistance to erosion and wear caused by the repeated opening and closing of said servo valve 101. Some such materials can be made from cemented ceramics or carbides such as aluminum oxide, silicon carbides, tungsten carbides. Although such hard materials are generally better in applications, it can be seen that in some embodiments, standard metal or plastic components may be used as a means to reducing manufacturing costs. Having the edge of the servo tip 124 be sharp where it is in contact with servo seat 170 significantly adds to the cutting and sweeping ability of the servo valve 101. The action of rotating the servo shaft 126 in effect causes the sharp knife-like edge of the servo tips 124 to sweep across rotor face 175 of servo seat 170 and thereby cut any contaminants that may be obstructing servo holes 171. This shearing action is highly desirable in MWD applications where additives and contaminants in the drilling mud may frequently cause jams in some equipment.

[0083] Rotor section 151 includes stops 156 to limit rotation of servo rotor 120. Stops 156 are mechanical and rotationally fixed with respect to valve seat 170 and rotor section 151 of screen housing 103 and extend partially radially inward of the outer diameter of the servo seat. Stops 156 are formed on interior surface 152 of rotor section 151 of screen housing 103 and extend radially-inwardly along only some portions of the circumferential extent of screen housing 103 and extend axially toward servo seat 170 only around halfway of the axial extent of rotor section 151. Stops 156 have both a clockwise CW surface 163 and a counter-clockwise CCW surface 164. Each of CW surface 163 and CCW surface 164 may contact digits 125.

[0084] By extending inwardly for only some portions of that circumferential extent, stops define two arcuate sweep zones 158 of around 90 degrees or exactly 90 degrees, and which are rotationally fixed with respect to valve seat 170 and rotor section 151. Sweep zones 158 define an about or exactly 90-degree sweep arc 159 in which servo rotor 120 is permitted to move between starting points 161 and stopping points 162 (see FIG. 4B). The two digits 125, extending axially away from servo seat 170, and stops 156 extend axially toward servo seat 170 sufficiently for digits 125 to contact stops 156 and for stops 156 to create limited rotation of servo rotor 120. Thus, each digit 125 extends into one of the two sweep zone 158 formed in rotor section 151 by stops 156, and the interaction between stops 156 and digit 125 in sweep zone 158 limits rotation of servo rotor 120 to sweep arc 159.

[0085] As stops 156 extend axially toward servo seat 170 only around halfway of the axial extent of rotor section 151, rotor section 151 also defines cylindrical open area 157, in which rotor arms 122 and servo tips 124 can rotate unobstructed (though their rotation is limited by interaction of stops 156 and digits 125).\

[0086] Starting points 161 and stopping points 162 may be created by mechanical interaction of matching faces on the stop and axially-extending digits on the arms of the rotor. In particular, a first (or clockwise “CW”) stopping point 162 is caused by mechanical interaction of CW faces 133 of digits 125 with a CW surface 163 on stop 156 on rotor section 151 at the CW end of a sweep zone 158. A second (or counterclockwise “CCW”) stopping point 162 is caused by mechanical interaction of CCW faces 134 of digits 125 with a CCW surface 164 on stop 156 on rotor section 151 at the CCW end of a sweep zone 158. These stopping points 162 thus define the permitted sweep arc 159 and are then starting points 161 when the direction of rotation or rotor section 151 is reversed.

[0087] Turning to FIGS. 3A, 3B, 6A-6B, in an embodiment of the invention, nozzle bulkhead 104 includes male connector 108 for connection to screen housing 103 and female connector 109 for connection to pulser 62. Cylindrical insert receiver 117 is formed adjacent or within female connector 109 to receive cylindrical nozzle insert 112 which seats on insert seat 113. Nozzle insert 112 includes reducer section 115 in which the cross-sectional flow area reduces to transition section 116, which is at or about the same size as throat 114 formed through insert seat 113. Flow of drilling fluid 66 can thus flow through nozzle insert 112, throat 113 and into female connector 109 to continue to pulser 62.

[0088] Turning to FIGS. 4, 7A-7J, and FIGS. 8-10, pulse (or pressure pulse) 200 is experienced in surface pressure 220 of drilling fluid 66 in communication with the pulser 62. Pulse 200 includes: (i) low-pressure state 221 (0-signal 226), as a substantially stable lower pressure associated with servo tips 124 obstructing servo holes 171 and with being at one of starting point 161; (ii) pressure increase transition 222, associated with servo tips 124 progressively opening up servo holes 171 as they rotate with rotor 120; (iii) high-pressure state 223 (1-signal 227), as a substantially stable and increased pressure, associated with servo tips 124 having fully opened up servo holes 171; (iv) pressure drop transition 224, associated with servo tips 124 progressively closing off servo holes 171 as they rotate with rotor 120; and (v) a return to low-pressure state 221 (0-signal 226), associated with servo tips 124 obstructing servo holes 171 and with being at one of stopping points 164. The period of time during which digital voltage signal 205 is at its high voltage state 227 is digital pulse width 201. The period of time between when pulser 62 starts to open and when pulser 62 starts to close is hydraulic pulse width 202, which corresponds closely to the period of time surface pressure 220 shows an increasing value before dropping off, thus pressure increase transition 222 and high-pressure state 223.

[0089] In an embodiment, digital pulse width 201 may be at or about 1 s, at or about 0.5 s, at or about 0.25 s, or at or about 0.1 s. In an embodiment, hydraulic pulse width 202 may be narrower, equal or wider than the associated digital pulse width 201 that causes the pulse 200 to be generated, with the difference in time explained by the lag between the onset of the digital voltage signal's transition to a high state or subsequently to a low state and the associated delay to the opening or subsequent closing of the servo tips 124 over servo holes 171.

[0090] FIG. 8 details the behavior of an embodiment of the current invention as it pertains to the operation of servo valve 101 in situations where servo rotor 120 of servo valve 101 moves continuously between starting and stopping points 161 and 162 without any coasting, braking or stops. Servo rotor 120 accelerates and travels continuously in one direction from servo tips 124 fully closing servo holes 171, to first rotate servo tips 124 to fully open servo holes 171, then continues to rotate to servo tips 124 then subsequently close and fully obstruct servo holes 171, changing rotary valve position from 0-degrees to 90-degrees. This action begins in closed state 231 and is followed by acceleration event 241 upon the reception of rising edge 206 of digital voltage signal 205. Current spike 331 in motor current 330 reflects power being applied to motor 238, followed by falling current 332. This acceleration causes servo rotor 120 to rotate to its open position 232 where servo tips 124 are in travel zone 160 in which servo holes 171 are not obstructed, initiating pulse 200. Servo rotor 120 continues to further rotate away from starting point 161 and causes servo tips 124 to sweep over servo holes 171, first partially obstructing them and then onto fully obstructing them to fully close servo valve 101, thus ending pulse 200. As shown in FIG. 8, servo rotor 120 then moves continuously between starting and stopping points 161 and 162 in the reverse direction, as shown by it changing rotary valve position back from 90-degrees to 0-degrees. During this rotation in the reverse direction, a second pulse 200 is created.

[0091] FIG. 9 details the behavior of an embodiment of the current invention as it pertains to the operation of the servo valve in situations where servo rotor 120 of servo valve 101 moves in one direction to open servo holes 171 by rotating servo tips 124 from fully closing servo holes 171 to fully open servo holes 171. This action begins in closed state 231 and is followed by acceleration event 241 upon the reception of rising edge 206 of digital voltage signal 205. Current spike 331 in motor current 330 reflects power being applied to motor 238, followed by falling current 332. This acceleration causes servo rotor 120 to rotate to its open position 232 where servo tips 124 are in travel zone 160 in which servo holes 171 are not obstructed, beginning pulse 200. Servo rotor 120 then enters coasting phase 242 where motor 238 is not energized (current 330 flowing through the motor is zero), but the rotational inertia of the rotating portions of servo valve 101 (including servo rotor 120, servo tips 124, servo shaft 126) causes servo rotor 120 to continue to rotate, to coast, servo rotor 120 towards the edge of travel zone 160. Here, the rotary valve position of servo valve 101 changes, albeit at a slower rate than the opening portion of the pulse event. When falling edge 207 is detected on digital voltage signal 205, servo pulser 64 initiates second acceleration event 241, causing another current spike 331 in motor current 330, and causing servo rotor 120 to further rotate away from starting point 161 at a higher speed towards the end of sweep zone 158, and causes servo tips 124 to sweep over servo holes 171, first partially obstructing them and then onto fully obstructing them to fully close servo valve 101, thus ending pulse 200. Prior to the end of pulse 200, and slightly before the end of the required rotation, servo pulser 64 may enter into deceleration event 243, to cause servo rotor 120 to decelerate as it approaches stop 156, with the aim being to cause digits 125 to contact stop 156 at the end of pulse 200 with a minimum amount of force, this creating a reasonably optimal pulse event where energy consumption is minimized and unnecessary impacts to the servo valve and stop surfaces are minimized or avoided. As shown in FIG. 9, servo rotor 120 then moves between starting and stopping points 161 and 162 in the reverse direction, as shown by it changing rotary valve position back from 90-degrees to 0-degrees. During this rotation in the reverse direction, a second pulse 200 is created.

[0092] FIG. 10 details the behavior of an embodiment of the current invention as it pertains to the operation of servo valve 101 in situations in which servo rotor 120 of servo valve 101 moves in one direction to open servo holes 171 by rotating servo tips 124 from fully closing servo holes 171 to fully open servo holes 171. This action begins in closed state 231 and is followed by acceleration event 241 upon the reception of rising edge 206 of digital voltage signal 205. Current spike 331 in motor current 330 reflects power being applied to motor 238, followed by falling current 332. This acceleration causes servo rotor 120 to rotate to its open position 232 where servo tips 124 are in travel zone 160 in which servo holes 171 are not obstructed, starting pulse 200. Servo pulser 64 may enter into deceleration event 243 prior to the full entry of servo tips 124 into travel zone 160 so as to cause the servo rotor 120 to stop rotation inside travel zone 160. Servo rotor 120 then enters intermediate stop phase 244 where motor 238 is not energized (current 330 flowing through the motor is zero), and motor 238 may be held in a brake state so as to stop its further rotation, this action being shows by the rotary valve position being steady and unchanging. Dwell time 203 is the period of time for which servo tips 124 are at rest and not obstructing servo holes 171; dwell time 203 thus enlarges pulse width 201. When falling edge 207 is detected on digital voltage signal 205, servo pulser 64 initiates a second acceleration event 241, causing current spike 331 in motor current 330, followed by falling current 332, and causing servo rotor 120 to further rotate away from starting point 161 at a higher speed towards the end of sweep zone 158, and causes servo tips 124 to sweep over servo holes 171, first partially obstructing them and then onto fully obstructing them to fully close servo valve 101, thus ending pulse 200. Prior to the end of pulse 200, and slightly before the end of the required rotation to fully close servo valve 101, servo pulser 64 may enter into deceleration event 243, to cause servo rotor 120 to decelerate as it approaches stop 156, with the aim being to cause digits 125 to contact stop 156 at the end of pulse 200 with a minimum amount of force, this creating a reasonably optimal pulse event where energy consumption is minimized and unnecessary impacts to the servo valve and stop surfaces are minimized or avoided. As shown in FIG. 10, servo rotor 120 then moves between starting and stopping points 161 and 162 in the reverse direction, with the same or other dwell time 203 as shown by it changing rotary valve position back from 90-degrees to 0-degrees. During this rotation in the reverse direction, a second pulse 200 is created. In this embodiment, the act of stopping the rotation of the servo in the middle of a single sweep or pulse event may require up to two acceleration and two deceleration events, and may result in higher power consumption when compared to modes that utilize no coasting or stopping, but may enable proper pulse generation and required valve motion control in geometries where the travel zones inside the swept zones are narrow or just sufficient to retain the servo tips in the travel zone, thereby allowing servo pulser diameters while allowing the use of larger servo tips and servo holes.

[0093] In an embodiment, rotor 120 oscillates between stopping points 162 in alternating clockwise and counterclockwise sweeps 210. Each sweep 210 in a given direction creates one full pulse 200. Thus, each sweep 210 starts with servo pulser 64 in closed state 231, with servo tips 124 at rest and fully obstructing servo holes 171. Sweep 210 then passes through servo pulser 64 being in open state 232, with servo tips 124 at rest or in motion, and not obstructing servo holes 171. Sweep 210 then ends with servo pulser 64 back in closed state 231, with servo tips 124 at rest and fully obstructing servo holes 171. Sweep 201 may have a characteristic sweep rate 212, being the number of sweeps 210 in a unit time, ordinarily per second, as well as sweep time 213 being the time to complete one sweep 210.

[0094] In an embodiment, pulse rate 204 of servo pulser 64 is the same or substantially the same as sweep rate 212. That is, servo pulser 64 creates one full pulse 200 in one sweep 210 of rotor 120. In this embodiment, sweep time 213 also correlates to the time period required to complete one pulse (not pulse width 201).

[0095] In an embodiment, each sweep 210 in a given direction creates one full pulse 200. Each sweep 210 starts with rotor 120 at one of stopping points 162, with drilling fluid 66 at in low pressure state 221 indicating 0-signal 226, then drilling fluid 66 passing through pressure rise transition 222, then reaching high pressure state 223 indicating 1-signal 227, remaining at that pressure for pulse width 201, then drilling fluid 66 passing through pressure drop transition 224, then drilling fluid 66 returning to high pressure state 221 indicating 0-signal 226.

[0096] In an embodiment, rotor 120 oscillates between stopping points 162 in alternating clockwise/counterclockwise sweeps 210. Each sweep 210 in a given direction creates one full pulse, in a 0-signal-1-signal-0-signal progression (226-227-226) (or 0-1-0 progression 228). In an embodiment, servo pulser 64 creates a full pulse 200, rotor 120 beginning at a CCW stop 156 and rotating in a clockwise direction in 0-1-0 progression 228 and ending at CW stop 156. Then servo pulser 64 creates another full pulse 200, rotor 120 beginning at the CW stop 156 and rotating in a counterclockwise direction in 0-1-0 progression 228 and ending at the CCW stop 156.

[0097] In an embodiment, rotor 120 oscillates clockwise and then counterclockwise to create two consecutive pulses 200, in a 0-1-0-1-0 progression 229, beginning at the CCW stop 156 and rotating in a clockwise direction to the CW stop 156, then rotating in a counterclockwise direction from the CW stop 156 to the CCW stop 156.

[0098] In an embodiment with an intermediate stop, rotor 120 of servo pulser 64 oscillates between stopping points 162 in alternating clockwise/counterclockwise sweeps 210 with intermediate stop 244 (between stopping points 156) with servo pulser 64 in open state 232. Each sweep 210 in a given direction creates one full pulse 200. Each sweep 210 starts with electric motor 328 driving servo shaft 126, accelerating rotor 120 (acceleration 241) from closed state 231 of servo pulser 64 (servo tips 124 at rest and fully obstructing servo holes 171) towards servo pulser 64 being in open state 232. Then, after an optional coasting event 242, electric motor 328 then decelerates rotor 120 (deceleration 243) so that it stops for dwell time 203 with servo pulser 64 in open state 232 (servo tips 124 not obstructing servo holes 171), creating pulse width 201 of pulse 200. Then electric motor 328 accelerates 241 rotor 120 from open state 232 (in the same direction as the previous acceleration 241) towards servo pulser being in closed state 231. Then, after an optional coasting 242, electric motor 238 decelerates 243 rotor 120 so that it stops with servo pulser 64 in closed state 231 (servo tips 124 at rest and fully obstructing servo holes 171). Each sweep 210 is through sweep arc 159 of at or about 90 degrees and each such arc may include two acceleration events 241 and deceleration events 243. Dwell time 203 exists between first deceleration event 243 and second acceleration event 241, and coasting event 242 is, optionally, between acceleration events 241 and then deceleration events 243.

[0099] In an embodiment with no intermediate stop, rotor 120 of servo pulser 64 oscillates between stopping points 156 in alternating clockwise/counterclockwise sweeps 210 with no intermediate stop between stopping points 156. Each sweep 210 in a given direction creates one full pulse 200. Each sweep 210 starts with electric motor 238 driving servo shaft 126, accelerating 241 rotor 120 from closed state 231 toward servo pulser being in open state 232. Then, after an optional coasting event 242, electric motor 328 then optionally decelerates 243 rotor 120 to extend the time for which servo pulser 64 is in open state 232, creating pulse width 201 of pulse 200. Then electric motor 328 optionally accelerates 241 rotor 120 (in the same direction as the previous acceleration 241) toward servo pulser 64 being in a closed state 231. Then, after an optional coasting event 242, electric motor 328 decelerates 243 rotor 120 so that it stops with servo pulser 64 in closed state 231. Each sweep 210 is through sweep arc 159 of at or about 90 degrees and each such arc includes at least one acceleration event 241 and at least one deceleration event 243 and may include two of each. Any coasting event 242 exists, optionally, between acceleration event 241 and then deceleration event 243, and between deceleration event 243 and acceleration event 241.

[0100] Turning to FIG. 11, in an embodiment, a microcontroller in servo pulser 64 carries out feedback/decision loop 400 between hyraulic pulses (and sweeps) to determine how fast or slow it should drive servo rotor 120, including if it should carry out an intermediate stop or carry out a coasting operation. Feedback/decision loop 400 computes and executes the desired velocity/acceleration, coasting or dwell profile, having received and/or calculated the time required to move the rotating portion of the valve, and other information on one or more previous pulses, such as sweep time 213, digital pulse width 201, applied current.

[0101] Loop 400 includes initiating pulse command 402, followed by slow/fast evaluation step 406 in which saved sweep time 213 (from the last pulse) is compared to digital pulse width 201 (from the last pulse). If sweep time 213 is not greater, then the valve closed faster than commanded, leading to coast mode check 410. If coast mode is off, then commands are issued to motor 328 to carry out an acceleration event 241 to drive servo rotor 120 to intermediate stop 244 in travel zone 160. Following that stop, pulse end check 416 checks if it is time to complete the pulse, e.g. if sufficient dwell time 203 has now elapsed that servo rotor 120 should be moved to the final position at stopping point 162. If the answer is no, it loops back to pulse end check 416 until it answers yes; if the answer is yes, final position order 420 causes the commands to be issued to carry out an acceleration event 241 to drive motor 328 to drive servo rotor 120 to stopping point 162, including an optional deceleration 243. If coast mode is on, then coasting process step 426 causes coasting event 242 to be carried out across servo holes 171 in place of intermediate stop 244 described above. If sweep time 213 is greater, then the valve closed more slowly than commanded, leading to the close fast command 430. In this case servo rotor 120 is commanded to move continuously between starting and stopping points 161 and 162 without any coasting, braking or stops. Thus, commands are issued to carry out an acceleration event 241 to drive motor 328 to drive servo rotor 120 to directly to stopping point 162 using a high or max current to motor 328. Following each of steps 420, 426, and 430, sweep time 213 and digital pulse width 201 are saved for use in the next pulse in save data step 436. Then, in reversal step 438, the direction of the next pulse is set to the opposite direction of the current pulse. Then, in waiting step 440, the system delays until the next pulse is initiated, leading back to step 402. Thus, the system uses an algorithmic feedback loop to control the speed and timings of the servo valve.