Oscillating shear valve for mud pulse telemetry and its operation

Abstract

The present invention describes a method and system for generating pulses in a drilling fluid. The method includes driving a rotor to rotate relative to a stator of a pulser assembly in an oscillating manner. The oscillating manner includes rotating a blocking element from an intermediate position to a first blocked angular position, and rotating the blocking element from the first blocked angular position to a second blocked angular position, such that selective blocking occurs. When drilling fluid flows through the drill string to generate pressure pulses in the drilling fluid, the rotation of the at least one blocking element selectively blocks a stator flow channel, and the oscillating manner is an oscillation of the blocking element between the first blocked angular position and the second blocked angular position, such that a single oscillation occurs between the two blocked states of the stator flow channel.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of the earlier filing date of U.S. application serial number 62 / 949,731, filed December 18, 2019, the entire disclosure of which is incorporated herein by reference. Background Art Technical Field

[0004] The present disclosure relates to drilling fluid telemetry systems, and more particularly to telemetry systems incorporating an oscillating shear valve for regulating the pressure of drilling fluid circulating in a drill string within a wellbore.

[0005] Description of Related Technology

[0006] Drilling fluid telemetry systems (often referred to as mud pulse systems) are particularly well-suited for telemetry (transmission) of information from the bottom of a borehole to the Earth's surface during subsurface operations (e.g., oil well drilling operations). The telemetry information typically includes, but is not limited to, parameters such as pressure, temperature, direction, and wellbore deviation. Other parameters include well logging data such as resistivity, acoustic density, porosity, induction, self-potential, and pressure gradient of various formations. This information can be crucial to the efficiency of drilling operations.

[0007] Telemetry operations use mud pulse valves to generate pressure pulses within the fluid (i.e., drilling mud). Mud pulse valves must operate under extremely high downhole static pressures, high temperatures, high flow rates, and various aggressive flow types. Under these conditions, the mud pulse valve must be able to generate pressure pulses of approximately 100 psi to 300 psi.

[0008] Different types of valve systems can be used to generate downhole pressure pulses for telemetry. Valves that open and close a bypass from the inside of the drill string to the wellbore annulus generate negative pressure pulses, as seen, for example, in U.S. Patent No. 4,953,595. Valves placed in the circulating mud flow with controlled restriction are often referred to as positive pulse systems, as seen, for example, in U.S. Patent No. 3,958,217. The entire contents of these patents are incorporated herein by reference.

[0009] It is desirable to increase mud pulse data transmission rates to accommodate the large amounts of measured downhole data that need to be transmitted to the surface. A major drawback of available mud pulse valves is their low data transmission rates. Increasing the data rate with available valve types results in unacceptably high power consumption, unacceptable pulse distortion, or may be physically impractical due to erosion, washout, and abrasive wear. Due to their low activation / operating speeds, nearly all existing mud pulse valves are capable of only generating discrete pulses. In order to effectively use a carrier wave to transmit a frequency-shifted (FSK) or phase-shifted (PSK) encoded signal to the surface, the actuation speed must be increased and fully controlled.

[0010] An example of a negative pulse valve is shown in U.S. Patent No. 4,351,037. The entire contents of this document are incorporated herein by reference. The present technology includes a downhole valve for discharging a portion of the circulating fluid from the interior of the drill string into an annular space between the tubular string and the wall of the borehole. The drilling fluid circulates downward along the interior of the drill string, flows out through the drill bit, and ascends along the annular space to the surface. By temporarily discharging a portion of the fluid flow from a side port, a transient pressure drop is generated and the transient pressure drop is detectable at the surface to provide an indication of the downhole discharge. The downhole instrument is arranged to generate a signal or mechanical action to form the above-mentioned discharge when a downhole detection event occurs. The disclosed downhole valve is partially defined by a valve seat having an inlet and an outlet and a valve stem that can move to an inlet end of the valve seat and move away from the inlet end of the valve seat in a linear path with the drill string.

[0011] As those skilled in the art will appreciate, all negative pulse valves require a high pressure differential below the valve (i.e., downhole) to generate a sufficient pressure drop when the valve opens. Due to this high pressure differential, negative pulse valves are generally easy to clean. Generally, it is undesirable to bypass flow above the drill bit into the annulus. Therefore, it is important to ensure that the valve can fully close the bypass. Each time the valve is actuated, it impacts the valve seat. Due to this impact, negative pulse valves are more susceptible to mechanical and abrasive wear than positive pulse valves.

[0012] Compared to negative pulse valves, positive pulse valves can, but do not need to, completely close the flow path to operate. Positive lift valves are less susceptible to seat wear. The primary force acting on positive lift valves is hydraulic pressure, as the valve opens or closes against the flow stream. To reduce actuation power, some positive lift valves are hydraulically actuated, as described in U.S. Patent No. 3,958,217. The entire contents of this document are incorporated herein by reference. In this configuration, the main valve is indirectly operated by a pilot valve. The low-power pilot valve closes the flow restriction, which activates the main valve to create a pressure drop. The power consumption of this valve is very low. A disadvantage of this valve is the passive operation of the main valve. At high actuation rates, the passive main valve cannot follow the actively operated pilot valve. As a result, the pulse signal generated downhole will become highly distorted and almost undetectable at the surface.

[0013] Alternative configurations include rotating disc valves, which are configured to open and close a flow channel perpendicular to the flow stream. The hydraulic force acting on this type of valve is less than that of a poppet-type valve. However, as actuation speed increases, dynamic inertial forces become the dominant power drain. For example, U.S. Patent No. 3,764,968 describes a rotary valve configured to transmit frequency-shift key (FSK) or phase-shift key (PSK) encoded signals. The entire contents of this document are incorporated herein by reference. The valve uses a rotating disc and a non-rotating stator with multiple corresponding slots. The rotor is continuously driven by an electric motor. Depending on the motor speed, when the rotor intermittently interrupts the fluid flow, pressure pulses of a certain frequency are generated in the flow. The motor speed needs to be changed to change the frequency of the pressure pulses to allow FSK or PSK type signals. The number of pulses per rotor revolution corresponds to the number of slots in the rotor and stator. To change the phase or frequency, the rotor needs to increase or decrease its speed. This may require the rotor to rotate to overcome rotational inertia and achieve the new phase or frequency, requiring several pulse cycles to make the transition. For such a continuously rotating device, amplitude encoding of the signal is essentially impossible. To change frequency or phase, the large moment of inertia associated with the motor must be overcome, which requires a significant amount of power. When rotating continuously at a certain speed, a turbine can be used or gears can be included to reduce the system's power consumption. On the other hand, when the signal encoding switches from one speed to another, both options significantly increase the system's inertia and power consumption.

[0014] The above examples illustrate some of the key considerations when applying fast-acting valves to generate pressure pulses. Other considerations for using these systems in drilling operations include the extreme impact forces present in a moving drill string, such as dynamic (vibration) energy. This results in excessive wear, fatigue, and failure of the system's operating components. The unique challenges encountered in the drill string environment, including the need for a long-lasting system to prevent premature failure and component replacement, necessitate a robust and reliable valve system. Summary of the Invention

[0015] Provided herein are systems and methods for generating pulses in drilling fluid. The method includes driving a rotor in an oscillatory manner relative to a stator of a pulser assembly, wherein the pulser assembly includes a tool housing disposed along a drill string, and the stator and rotor are disposed within the tool housing, wherein the stator includes at least one stator flow channel for permitting drilling fluid to flow therethrough, and the rotor includes at least one blocking element configured to selectively block fluid flow through the at least one stator flow channel. The oscillatory driving comprises: rotating the at least one blocking element from a neutral position to a first blocking angular position, such that a first selective blocking of the at least one stator flow channel by the at least one blocking element occurs, wherein the neutral position is defined by minimal blocking of flow through the at least one stator flow channel by the at least one blocking element; and rotating the at least one blocking element from the first blocking angular position to a second blocking angular position opposite the neutral position of the first blocking angular position, such that a second selective blocking of the at least one stator flow channel by the at least one blocking element occurs. Rotation of the at least one blocking element selectively blocks the at least one stator flow channel as drilling fluid flows through the drill string to generate pressure pulses in the drilling fluid. Furthermore, the oscillating pattern is an oscillation of the at least one blocking element between the first blocking angular position and the second blocking angular position, so that a single oscillation exists between two blocking states of the at least one stator flow channel.

[0016] The rotary pulser assembly and system described herein are configured to be positioned along a drill string through which drilling fluid flows. The rotary pulser includes a housing configured to be supported along the drill string. A stator is supported by the housing, the stator having at least one stator flow channel extending from an upstream end to a downstream end of the stator. A rotor is positioned adjacent to the stator, the rotor including at least one blocking element, the rotor being rotatable to selectively block the at least one stator flow channel using the at least one blocking element. A motor is coupled to the rotor, wherein the motor assembly is operable to rotate the rotor relative to the stator. A controller is configured to drive the motor and rotate the rotor relative to the stator, wherein the controller is configured to drive the rotation of the rotor in an oscillating manner. The oscillating pattern includes: a first selective blocking of the at least one stator flow channel by the at least one blocking element occurring when the blocking element rotates from an intermediate position to a first blocking angular position, wherein the intermediate position is defined by minimal blocking of flow through the at least one stator flow channel by the at least one blocking element; and a second selective blocking of the at least one stator flow channel by the at least one blocking element occurring when the blocking element rotates from the first blocking angular position to a second blocking angular position, wherein the second blocking angular position is opposite the intermediate position of the first blocking angular position. Rotation of the blocking element selectively blocks the at least one stator flow channel when drilling fluid flows through the drill string to generate a pressure pulse in the drilling fluid. Furthermore, the oscillating pattern is an oscillation of the at least one blocking element between the first blocking angular position and the second blocking angular position, such that a single oscillation occurs between the two blocked states of the at least one stator flow channel.

[0017] Unless otherwise expressly stated, the aforementioned features and elements may be combined in various combinations without exclusivity. These features and elements and their operation will become more apparent from the following description and accompanying drawings. However, it should be understood that the following description and accompanying drawings are intended to be illustrative and explanatory in nature, rather than restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of this specification. The foregoing and other features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0019] Figure 1 is a schematic diagram showing a drilling rig 1 engaged in drilling operations in which embodiments of the present disclosure may be incorporated;

[0020] Figure 2A is a schematic diagram of a pulser assembly that may incorporate embodiments of the present disclosure;

[0021] Figure 2B yes Figure 2AA schematic diagram of a stator of a pulser assembly;

[0022] Figure 2C yes Figure 2A A schematic diagram of a rotor of a pulser assembly;

[0023] Figure 3 is a sequence of images of the operation of a pulser assembly according to one embodiment of the present disclosure;

[0024] Figure 4 is a schematic diagram of a pulser assembly according to one embodiment of the present disclosure;

[0025] Figure 5A is a sequence of operational images of a pulser assembly according to one embodiment of the present disclosure illustrating a transition from an open position to a first closed position;

[0026] Figure 5B yes Figure 5A An operational sequence of the pulser assembly showing a transition from a first closed position back to an open position;

[0027] Figure 5C yes Figure 5A An operational sequence of a pulser assembly illustrating a transition from an open position to a second closed position;

[0028] Figure 6A is a graph of angular position as a function of operating time according to one embodiment of the present disclosure;

[0029] Figure 6B is a graph of pressure as a function of operating time according to one embodiment of the present disclosure;

[0030] Figure 6C is a graph of power consumption of an electric motor driving a rotor during operation according to one embodiment of the present disclosure;

[0031] Figure 6D is a graph of current drawn by a motor during operation according to one embodiment of the present disclosure;

[0032] Figure 7 is a graph of pressure as a function of angular position of the pulser assembly;

[0033] Figure 8A is a graph of pressure as a function of time for alternative configurations of pulser assemblies;

[0034] Figure 8B is a graph of pressure as a function of time for alternative configurations of pulser assemblies;

[0035] Figure 9is a schematic diagram of a pulser assembly according to one embodiment of the present disclosure;

[0036] Figure 10 is a graph showing pressures based on different pressure curves for different pulser configurations;

[0037] Figure 11A is a schematic diagram of a rotor of a pulser assembly according to one embodiment of the present disclosure;

[0038] Figure 11B It is along Figure 11A The line BB shown is observed Figure 11A a side elevation view of a blocking element of a rotor;

[0039] Figure 11C It is along Figure 11A The line CC shown is observed Figure 11A A cross-sectional view of a blocking element of a rotor;

[0040] Figure 12A is a schematic diagram of a pulser assembly according to one embodiment of the present disclosure, shown in a starting orientation illustrating a transition from an open position to a first closed position;

[0041] Figure 12B Shown Figure 12A A series of operational orientations of a pulser assembly illustrating transition from a first closed position back through an open position;

[0042] Figure 12C Shown Figure 12A A series of operational orientations of the pulser assembly illustrating a transition from a low blocking position to a second closed position;

[0043] Figure 12D Shown Figure 12A Operational orientation series of pulser components;

[0044] Figure 13A is a graph of torque as a function of angular position of the pulser assembly; and

[0045] Figure 13B is a graph of torque as a function of angular position of a pulser assembly incorporating one embodiment of the present disclosure. DETAILED DESCRIPTION

[0046] The detailed description of one or more embodiments of the disclosed apparatus and methods presented herein is presented by way of example and not limitation with reference to the accompanying figures.

[0047] Figure 1is a schematic diagram showing a drilling rig 100 involved in a drilling operation. Drilling fluid 102 (also known as drilling mud) is circulated by a pump 104 through the inner bore of a drill string 106, downwardly through a bottom hole assembly (BHA) 108, through a drill bit 110, and then back to the surface through an annulus 112 between the drill string 106 and the borehole wall 114. The BHA 108 may include any of a plurality of sensor modules 116, 118, and 120. As will be understood by those skilled in the art, the sensor modules 116, 118, and 120 may include formation evaluation sensors, directional sensors, probes, detectors, and the like. Such sensors and modules are well known in the art and will not be described further. The BHA 108 also includes a pulser assembly 122. The pulser assembly 122 is configured to induce pressure fluctuations in the mud flow of the drilling fluid 102. The pressure fluctuations or pulses are propagated to the surface by the drilling fluid 102 in the drill string 106 and / or the drilling fluid 108 in the annulus 112 and are detected at the surface by a pulse sensor 124 and an associated control unit 126. As will be understood by those skilled in the art, the control unit 126 can be a general or special purpose computer or other processing unit. The pulse sensor 124 is connected to a flow line 128 and can be a pressure transducer or a flow transducer, as will be understood by those skilled in the art. The BHA 108 includes or defines a longitudinal axis.

[0048] Now turn Figures 2A to 2C , a schematic diagram of the pulser assembly 200 is shown. Figure 2A is a partial cross-sectional schematic diagram of the pulser assembly 200, Figure 2B is a schematic diagram of the stator 202 of the pulser assembly 200, and Figure 2C FIG is a schematic diagram of a rotor 204 of a pulser assembly 200. The pulser assembly 200 may be installed or otherwise used in a downhole system, such as a Figure 1 In this embodiment, the pulser assembly 200 is arranged as an oscillating shear valve assembly configured for mud pulse telemetry. As shown, the pulser assembly 200 is arranged in the inner bore of a tool housing 206. In some embodiments, the tool housing 206 may be a drilling collar in a bottom hole assembly (e.g., Figure 1). In other embodiments, the tool housing 206 may be a separate housing adapted to fit into the drill collar bore. Various other configurations are possible without departing from the scope of the present disclosure. The tool housing includes or defines a longitudinal axis H. The longitudinal axis H may be parallel to and / or aligned with the longitudinal axis S of the stator 202. In operation, for example, while drilling, a drilling fluid 208 will flow through the stator 202 and the rotor 204 and through the annulus between the pulser housing 210 and the inner diameter or surface of the tool housing 206. The pulser housing 210 includes or defines a longitudinal axis (not shown). The longitudinal axis of the pulser housing 210 may be parallel to the longitudinal axis H of the tool housing 206. The drilling fluid 208 may be referred to herein as drilling mud, drilling fluid, and / or mud. The drilling fluid may flow in a direction parallel to the longitudinal axis of the housing or BHA.

[0049] Figure 2A and Figure 2B The stator 202 is shown as being fixed relative to the tool housing 206 and the pulser housing 210. The stator 202 may define or include a plurality of longitudinal stator flow channels 212. The stator 202 includes or defines an upstream side 213 and a downstream side 215. Figure 2A and 2C The rotor 204 shown in FIG is disk-shaped with notched blades 214 (rotor blades) defining rotor flow passages 216 that are similar in size and shape to the stator flow passages 212 in the stator 202 (although not as long in the axial direction, as shown in FIG). Figure 2A 20). The rotor 204 includes or defines an upstream side 203 and a downstream side 205. Although shown as flow channels (defined by rotor blades), in some embodiments, holes or openings may be formed in the stator and rotor, respectively. The rotor flow channel 216 is configured so that the rotor flow channel 216 will align with the stator flow channel 212 at certain angular positions of the rotor to define a straight or substantially straight (i.e., axial) flow path. The rotor 204 is positioned adjacent the stator 202 and is configured to oscillate rotationally or be driven rotationally. Angular displacement (rotation) of the rotor 204 relative to the stator 202 will change the effective flow area of the axial flow path defined by the flow channels 212, 216 and thereby produce pressure fluctuations in the circulating mud column. In alternative embodiments, the rotor may not be disc-shaped, but may include an extension on the downstream side.

[0050] To achieve a pressure cycle, it is necessary to open and close the axial flow path by changing the angular positioning of the rotor blades 214 relative to the stator flow channel 212. This is accomplished by oscillating the rotor 204 about the rotor shaft axis R. The rotor blades 214 rotate in a first direction until the flow area is fully or partially restricted. This partial or complete restriction (or blockage) creates or generates a pressure increase in the fluid. The rotor blades 214 then rotate in the opposite direction to reopen the flow path. As the flow path opens, the pressure decreases. The angular displacement required to generate a pressure pulse depends on the design of the rotor 202 and stator 204. The narrower the flow path design of the pulser assembly 200, the smaller the angular displacement required to generate the pressure fluctuation. A relatively small angular displacement is generally desirable (and therefore relatively narrow flow channels 212, 216 may be more desirable). However, narrow flow channels can be blocked by debris or foreign particles in the fluid flow, so a compromise must be struck between narrow flow channels for low displacement and larger flow channels to allow debris to pass.

[0051] The power required to accelerate the rotor 204 is proportional to the angular displacement of the rotor when oscillating rotationally about the rotor shaft axis R. The smaller the angular displacement, the lower the actuation power required to accelerate or decelerate the rotor 204. As an example, due to the eight flow channels (rotor flow channels 216) on the rotor 204 and stator 202 (stator flow channels 212) and the maximization of the total flow channel cross-section, an angular displacement of approximately 22.5° is used to generate a pressure drop. Having this relatively low angular displacement angle ensures relatively low actuation energy, even at high pulse frequencies. In some configurations, it may not be necessary to completely block the flow of fluid through the flow path to generate a pressure pulse. Therefore, different amounts of blockage or angular rotation of the rotor 204 can be used to generate different pulse amplitudes.

[0052] like Figure 2AAs shown, rotor 204 is attached or operably coupled to rotor shaft 218. Thus, rotation of rotor shaft 218 can cause rotation of rotor 204. Rotor shaft 218 passes through seal 220 and is assembled through one or more bearings 222. Bearings 222 are configured to secure rotor shaft 218 in a radial and axial position relative to pulser housing 210. Rotor shaft 218 is operably connected to motor 224, wherein rotor shaft 218 is configured to be rotationally driven by motor 224. Motor 224 can be, for example, an electric motor, such as a reversible brushless DC motor, a servo motor, or a stepper motor. Motor 224 can be configured to be electronically controlled, such as by circuitry in electronics module 226. Electronics module 226 can enable precise operation of rotor 204, such as oscillatory movement in two rotational directions (e.g., clockwise and counterclockwise). Precise control of the position of rotor 204 provides for specific shaping of pressure pulses generated by the fluid flow (e.g., drilling mud) through pulser assembly 200. The electronic module 226 may include a programmable processor that may be preprogrammed to transmit data using any of a number of coding schemes including, but not limited to, amplitude shift keying (ASK), frequency shift keying (FSK), or phase shift keying (PSK), or a combination of these techniques.

[0053] In some embodiments, the tool housing 206 may include one or more pressure sensors (not shown) mounted at locations above and below the pulser assembly 200. Such pressure sensors may be configured with sensing surfaces exposed to the fluid in the drill string bore. The pressure sensors may be powered by the electronics module 226 and may be configured to receive surface-transmitted pressure pulses. The processor and / or circuitry within the electronics module 226 may be programmed to change data encoding parameters based on the received surface-transmitted pressure pulses. The encoding parameters may include the type of encoding scheme, baseline pulse amplitude, baseline frequency, rotor angular displacement, rotor angular position at neutral position, or other parameters that affect data encoding. In an alternative embodiment, the BHA 108 may include a turbine driven by mud flow. In such an embodiment, the turbine may be configured to receive surface-transmitted pulses by measuring turbine speed fluctuations.

[0054] The pulser housing 210 can be filled with a suitable lubricant 228 to lubricate the bearings 222 and utilize the downhole pressure of the drilling mud 208 to pressure-compensate the interior of the pulser housing 210. The bearings 222 are typical anti-friction bearings known in the art and will not be described further. In some embodiments, and as shown, the seal 220 can be configured as a flexible bellows seal that is directly connected to the rotor shaft 218 and the pulser housing 210. Thus, the seal 220 can seal (e.g., airtightly) the pulser housing 210 filled with the lubricant 228 (e.g., oil). Angular movement or rotation of the rotor shaft 218, such as driven by the motor 224, causes the flexible material of the seal 220 to twist, thereby accommodating the angular movement while maintaining the seal of the lubricant 228 within the pulser housing 210. In some embodiments, the flexible bellows material of the seal 220 can be an elastomeric material, a fiber-reinforced elastomeric material, or other suitable material as will be appreciated by those skilled in the art. Depending on the material of the seal 220, the arrangement of the components, etc., it may be desirable to keep the angular rotation of the rotor shaft 218 relatively small so that the material of the seal 220 is not overly stressed by the torsional motion. In other configurations, the seal 220 may be an elastomeric rotary shaft seal or a mechanical face seal, as will be understood by those skilled in the art. That is, the seal 220 may employ various configurations and arrangements to provide a sealed, lubricant-filled interior of the pulser assembly 200 without departing from the scope of the present disclosure.

[0055] In some embodiments, the motor 224 may be configured with a double-ended motor shaft or a hollow motor shaft. In some such embodiments, one end of the motor shaft is attached to the rotor shaft 218 of the rotor 204 of the pulser assembly 200, and the other end of the motor shaft is attached to a torsion spring 230. The torsion spring 230 may be anchored to an end cap 232. In such embodiments, the torsion spring 230, the rotor shaft 218, and the rotor 204 are configured as a mechanical spring-mass system. The torsion spring 230 is designed so that the natural frequency of the spring-mass system is at or near the desired oscillation pulse frequency of the pulser assembly 200. Methods for designing resonant torsion spring-mass systems are well known in the mechanical arts and will not be described here. The advantage of a resonant system is that once the system is in resonance, the motor 224 only needs to provide power to overcome external forces and system damping, while the rotational inertia force is balanced by the resonant system. In alternative embodiments, the torsion spring may be attached to the rotor shaft.

[0056] Embodiments of the present disclosure relate to rotary pulser assemblies (i.e., pulsers) and methods for operating such assemblies. The pulser assembly includes a housing, a stator supported by the housing, a rotor adjacent to the stator, and a motor assembly coupled to the rotor, such as described above with respect to Figures 2A to 2CAs shown and described. The electronic module is configured to control the movement or operation of the motor assembly and, therefore, the rotation of the rotor. The movement or rotation of the rotor may be oscillation. That is, the rotor may be driven in a first rotational direction D1 and in a second (opposite) rotational direction D2, with a change of direction between such drives. In some embodiments, a specific rotation angle may be performed relative to a center position so that, when starting from a center or intermediate position, the rotor may be driven in a predefined rotational angle in a first direction, and when such an angle is reached, the direction of rotation may be reversed and thus rotate in a second direction. As the rotor rotates in the second rotational direction D2, the rotor may pass through the center or intermediate position and continue to rotate to the same predefined rotational angle (but opposite to the first rotational direction D1). The term opposite refers to the opposite rotational direction of the rotor or the angular position of the rotor that can be reached from the intermediate position by rotating the rotor in the opposite rotational direction. That is, rotating from the angular position of the rotor to the relative angular position includes passing through the intermediate position.

[0057] The rotor 204 may include one or more blocking elements 214, such as Figures 2A to 2C The obstructing element may be sized and shaped to at least partially (and possibly completely) block fluid flow through a flow passage 212, duct, or opening in a stator disposed adjacent to the rotor (e.g., as Figures 2A to 2C shown). Figure 2B and Figure 2C Cross-sectional views of the stator 202 and rotor 204, viewed from an uphole perspective, are provided, respectively. When the rotor is rotated by the motor, one or more blocking elements 214 and one or more rotor flow channels 216 rotate with the rotor. In a default or stationary state (when the motor is off), as indicated by the orientation of the stator 202 and rotor 204 relative to each other, the rotor can be arranged so that the flow path is open and the blocking elements do not block, or minimally block, the stator flow channels. However, the rotor is configured to be driven in a rotational manner such that the blocking elements can block or otherwise restrict fluid flow through the stator flow channels (i.e., by blocking the stator flow channels).

[0058] Since the flow paths are open or at least partially open (e.g., minimum blocking position) when at rest (or in a motor-off state), the rotor can be rotated from an intermediate (open) position to a maximum blocking position (i.e., closed or partially closed), whereby one or more blocking elements block the flow of fluid through one or more corresponding flow paths of the stator. As an example, when the rotor rotates by a predefined first blocking angle α1 (e.g., Figure 3 As shown in FIG, the rotor can rotate in a first rotation direction D1 to block the flow channel. The rotor will stop rotating at a first blocking angle α1 (angular velocity ω min1 = 0), and then reverses in the second rotation direction D2, thereby reducing the resistance until the minimum resistance is reached at the intermediate position α0 (as Figure 3 The rotation will continue from the intermediate position α0 in the same direction (i.e., the second rotation direction D2) and at the maximum rotation speed ω of the rotor. max Passing or crossing the middle position, and rotating to the second maximum blocking position (such as Figure 3 Again, the rotor will stop rotating at the second blocking angle α2 (ω min =0), then reverses the direction of rotation (ie, enters the first rotation direction D1), again reducing the resistance until a minimum resistance is reached at the intermediate position α0.

[0059] The rotation will continue from the intermediate position α0 in the same direction (ie the first rotation direction D1) and at the maximum rotation speed ω of the rotor max Passing or crossing the middle position α0, and rotating back to the first maximum blocking position at the first blocking angle α1. max Reversal (D1 to D2) past the first blocking angular position α1 of the intermediate position α0 to the direction of rotation again at the maximum rotation speed ω max The rotor cycle of reversing (D2 to D1) and passing through the intermediate position α0 to the second blocking angle α2 of the first blocking angle position α1 represents one rotational oscillation cycle of the rotor. The rotor flow channel aligned with the specific stator flow channel at the intermediate position α0 when the motor is turned off aligns with the specific stator flow channel at the intermediate position α0 twice during one rotational oscillation cycle of the rotor. During the two alignments during one rotational oscillation cycle, the rotational speed is maximum, i.e., ω in the rotation direction D2. max and ω along the rotation direction D1 max In such a configuration and operation, the intermediate position α0 may represent or be defined by an angle of 0°. The specific rotor cycle from a first closed position having a minimum rotational speed, through an open position having a maximum rotational speed, to a second closed position, and back through the open position to the first closed position is new and provides significant advantages over the prior art systems described herein with respect to the pulse patterns produced by the rotary pulser.

[0060] For example, turning Figure 3, a series of schematic diagrams illustrating the operation of a portion of a pulser assembly 300 according to one embodiment of the present disclosure. The pulser assembly 300 includes a stator 302 and a rotor 304 rotatable relative to the stator 302. The rotational movement of the rotor 304 can be driven by a motor, as described above. The stator 304 includes a stator flow channel 306 and the rotor 304 includes a rotor flow channel 308, and when the rotor flow channel 308 is aligned with the stator flow channel 306, a flow path is defined through the pulser assembly 300. The rotor 304 also includes at least one blocking element 310 that is rotatable to block or otherwise prevent fluid from flowing through the stator flow channel 306.

[0061] Figure 3 The series of schematic diagrams in show the oscillatory motion of the rotor 304 relative to the stator 302 and, in particular, the obstruction or blocking provided by the blocking element 310 (eg, a portion of the rotor without a flow channel) as the blocking element moves relative to the stator flow channel 306. Figure 3 An orientation series (a)-(l) is shown, which shows the orientation of the rotor 304 relative to the stator 302. Figure 3 In orientation (a), the rotor 304 is at rest (e.g., the drive motor is off), the rotor flow channel 308 is aligned with the stator flow channel 306, and the blocking element 310 does not block or otherwise obstruct flow through the flow path defined by the aligned flow channels 306, 308, or minimally obstructs flow through the flow path defined by the aligned flow channels 306, 308. The size and shape of the blocking element 310 are configured to ensure sufficient obstruction (partial or complete) of the stator flow channel 306 when the blocking element 310 is moved to align with the stator flow channel 306. The following series of orientations (a)-(l) will be with respect to first rotating counterclockwise (e.g., a first rotational direction D1) in orientations (b)-(d), then rotating clockwise (e.g., a second rotational direction D2) in orientations (e)-(j), and concluding with a counterclockwise rotation back to the starting orientation in orientations (k)-(l) (e.g., an intermediate position). It should be understood that with respect to the above description, counterclockwise and clockwise directions are defined relative to a downhole perspective on the rotor. The terms downstream and downhole refer to the location of the pulser assembly on the drill bit side. The terms upstream and uphole refer to the location of the pulser assembly on the surface side.

[0062] In orientation (a), the rotor 304 is shown in the bottom angular position α0. When the pulser assembly 300 is at rest and / or the motor is off, the bottom angular position α0 is a default angle relative to the reference orientation of 0°. In some configurations, as described below, the rotor 304 can be biased to the bottom angular position α0 so that when the motor is off, regardless of the position of the rotor 304, the rotor 304 will return to the bottom angular position α0 due to a biasing force. Such biasing can be achieved by a torque spring (e.g., a torsion spring) or other similar biasing element, which is configured to return the rotor 304 to the bottom angular position α0 when no rotational force is applied thereto. As the rotor oscillates about the bottom angular position α0 (the neutral position), the spring load of the torsion spring is zero at the bottom angular position α0. In the neutral position, the torsion spring is untensioned (e.g., the spring is released). It should be noted that the torsion of the seal 220 may also contribute to the biasing force toward the bottom angular position α0. In alternative embodiments, an electric motor (eg, an electric brake) or another electrical or mechanical mechanism may bias the rotor in the base angle position.

[0063] In orientation (b), rotor 304 rotates counterclockwise relative to stator 302 (e.g., first rotational direction D1), causing a portion of blocking element 310 to block or otherwise obstruct a portion of stator flow channel 306. As shown, in orientation (b), the amount of alignment or overlap between stator flow channel 306 and rotor flow channel 308 is less than when rotor 304 is at base angle α0. Consequently, the amount of obstruction of the flow path defined by rotor flow channel 308 and stator flow channel 306 increases, thereby increasing the pressure of the fluid.

[0064] In orientation (c), rotor 304 rotates further counterclockwise relative to stator 302 (e.g., first rotational direction D1), causing the portion of blocking element 310 that obstructs or blocks stator flow channel 306 to increase. As shown, in orientation (c), the amount of alignment or overlap between stator flow channel 306 and rotor flow channel 308 is less than when rotor 304 is in orientation (b). Consequently, the amount of obstruction of the flow path defined by rotor flow channel 308 and stator flow channel 306 is further increased, thereby increasing the pressure of the fluid even more than in orientation (b).

[0065] In orientation (d), rotor 304 rotates further counterclockwise relative to stator 302, causing blocking element 310 to completely block or obstruct stator flow channel 306. As shown, in orientation (d), rotor flow channel 308 does not overlap any straight portion of stator flow channel 306, and therefore, the pressure increase is greater than in orientations (b) and (c). Due to the axial gap, or distance, between the adjacent faces of rotor 304 and stator 302 (between the downstream side of the stator and the upstream side of the rotor), flow is forced to flow around the outer diameter of rotor 304, through the rotor flow channel, the axial gap, and ultimately through rotor flow channel 308. In orientation (d), rotor 304 has rotated through the full range of a single blocking oscillation and thus ends at the first blocking angular position α1. When rotor 304 has rotated to the first blocking angular position α1, the direction of rotation (e.g., the first rotational direction D1) changes (reverses) to clockwise rotation. Consequently, at the first blocking angular position α1, the rotational speed of rotor 304 reaches zero and reverses direction (e.g., the second rotational direction D2). In orientation (d) and a first blocked angular position α1, a biasing member (e.g., a torsion spring) provides a maximum repulsive force F1 (a first biasing force) toward the bottom angular position α0 of the rotor 304. The gap between the adjacent faces of the rotor 304 and the stator 302 can be several millimeters wide to several centimeters wide. A typical gap can be between 2 mm wide and 6 mm wide.

[0066] Orientations (e)-(j) illustrate clockwise rotation of the rotor 304 relative to the stator 302. As shown, the flow path defined by the overlap of the rotor flow channel 308 and the stator flow channel 306 increases in magnitude as the rotor 304 rotates. In orientation (g), the rotor 304 passes through the base angle α0 and then continues past the base angle α0 in a clockwise direction (e.g., the second rotational direction D2). In orientation (j), the rotor 304 rotates completely in the clockwise direction of the oscillation, achieving the second maximum blockage. In orientation (j), the rotor 304 has rotated through the full range of a single blocking oscillation and ends at the second blocking angular position α2. When the rotor 304 has rotated to the second blocking angular position α2, the direction of rotation (e.g., the second rotational direction D2) will change to counterclockwise rotation (e.g., the first rotational direction D1), and thus, at the second blocking angular position α2, the rotational speed of the rotor 304 will reach zero and reverse direction. As shown, in orientation (j), the rotor flow channel 308 does not overlap any straight portion of the stator flow channel 306, and thus, at the second blocked angular position α2, a maximum pressure increase is achieved. In orientation (j) and the blocked angular position α2, the biasing member (e.g., a torsion spring) provides a maximum repulsive force F2 (a second biasing force) toward the bottom angular position α0, where the repulsive force F2 has at least a component in the opposite direction of the first biasing force F1. The biasing forces F1 and F2 act on the rotor 304 to support rotation back to the bottom angular position α0. The biasing forces F1 and F2 can be tangential forces and act in opposite tangential directions, where the tangential direction relates to the circumference of the rotor. The value of the second blocked angle α2 can be equal to the value of the first blocked angle α1.

[0067] exist Figure 3 , orientation (k)-(l) shows the rotor 304 returning to the bottom angle α0 so that the stator flow channel 306 and the rotor flow channel 308 are aligned and the flow path is fully open. In orientation (l), the rotor reaches the starting position (a) again. If another pulse is desired, the rotor 304 can continue to rotate counterclockwise, as shown in orientation (b)-(d), or even a complete oscillation of orientation (b)-(j) or orientation (b)-(l). For the series of pressure pulses, the operating sequence through orientations (d) to (j) and the corresponding counterclockwise sequence of orientations (j) to (d) are repeated. Such a continuous series of oscillations can produce a continuous series of pressure pulses. The term "fully open" as used in this disclosure refers to the rotor orientation relative to the stator that corresponds to the maximum fluid flow and / or corresponds to the minimum obstruction of the flow path in a given stator-rotor combination. The rotor flow channel is perpendicular to the tool housing 206 ( Figure 2A ) of the longitudinal axis and the drilling fluid 208 ( Figure 2A ) may be smaller in cross-section in at least one of the flow directions.

[0068] Therefore, as regards Figure 3As described, the pulser assembly 300 is configured to be stationary in the open position and to oscillate between two closed positions during operation. Furthermore, during operation, since the open position is between the two closed positions, the blocking element 310 of the rotor 304 will rotate at a maximum rotational speed of + / - ω as the rotor flow channel 308 passes through the stator flow channel 306 twice in the rotational directions D1 and D2 during one rotor cycle, assuming sinusoidal movement of the rotor 304. max In addition, the blocking element 310 of the rotor 304 will reach a zero rotational speed ω within the rotational movement range (ie, the first blocking angle α1 and the second blocking angle α2, the first reversal point and the second reversal point). min1 / ω min2 , and thus when the rotation direction changes from D1 to D2 or D2 to D1 , the stator flow channel 306 will be blocked (ie, maximum obstruction) at the maximum oscillation configuration (α1 , α2 ) of the pulser assembly 300 .

[0069] Advantageously, the pulser assembly of the embodiment described herein has a much higher speed or transition through the open position when assuming sinusoidal movement of the rotor 304 compared to existing oscillating configurations. The sinusoidal input of the rotational movement has a low speed region (i.e., maximum obstruction, minimum rotational speed) in the two closed positions, with the speed being at a maximum (i.e., minimum obstruction, maximum rotational speed) through the middle of the movement cycle. In the middle position of the arrangement, obstruction is minimal or zero (i.e., open passage through the flow path defined by the stator and rotor flow channels). Because pressure buildup rises overproportionally toward the closed position and underproportionally near the open position, the faster transition through the open state and the slower transition through the closed state produce a more sinusoidal pressure signature over time. Such a sinusoidal pressure signal is beneficial for decoding pressure pulses at the surface, thus providing a more efficient system.

[0070] Additionally, as described above, the base angle α0 is the default angle when the pulser assembly is stationary and / or the motor is off. That is, in the de-energized state (i.e., with power off), the rotor flow passages automatically align with the stator flow passages (i.e., the open state). This default to the open state can be achieved using a torsion spring, such as shown and described in U.S. Patent No. 6,626,253, entitled "Oscillating Shear Valve for Mud Pulse Telemetry," the entire contents of which are incorporated herein by reference.

[0071] In some embodiments, a torsion spring may be attached to the motor and pulser housing. The torsion spring is designed so that the combination of the torsion spring and the rotating mass (i.e., the rotor, rotor shaft, seals, etc.) produces a torsional resonant spring-mass system near the desired operating frequency of the pulser assembly. Thus, the pulser assembly can have a neutral torque free state in an intermediate position. Thus, when the motor is powered off or turned off, the open position can be maintained. The advantage of the open position (rather than a mid-block position as in U.S. Patent No. 6,626,253) is that it produces a lower flow restriction (e.g., a lower pressure drop) in the power-off state and is less sensitive to blockage or accidental obstruction in the power-off state. Compared to existing systems, the rotor cycle (including passing through the open position at maximum rotational speed) results in an oscillation (α1, α2) from the intermediate position that is twice the oscillation angle and a maximum oscillation speed of + / - ω. max is half the oscillation speed.

[0072] Now turn Figure 4 , shows a schematic diagram of a pulser assembly 400 according to one embodiment of the present disclosure. The pulser assembly 400 can operate similarly to that described above, having an open default or de-energized position and a driven oscillation between two closed positions. The pulser assembly 400 includes a tool housing 402 through which drilling mud 404 can pass. Disposed within the tool housing 402 is a stator 406 and a rotor 408 disposed relative to the stator 406. In this exemplary embodiment, the stator 406 defines a plurality of stator flow channels 410, and the rotor 408 includes an equal number of rotor flow channels 412. As described above, when the rotor flow channels 412 are aligned with the stator flow channels 410, a flow path can be defined so that the drilling mud 404 can flow through the pulser assembly 400. In operation, the rotor 408 may be rotatably driven by a motor 414 to have one or more blocking elements 416 that will block (partially or completely) the stator flow passage 410 to block the flow of drilling mud 404 through the pulser assembly 400 .

[0073] The pulser assembly 400 includes a rotor shaft 418 that operably connects the motor 414 to the rotor 408. As will be appreciated by those skilled in the art, the motor 414 may be a brushless motor. The rotor shaft 418 is rotatably mounted within a bearing housing 420 via one or more bearings 422. A lubricant 424 may be contained within the bearing housing 420 to lubricate the rotor shaft 418 and enable rotational movement of the rotor shaft when driven by the motor 414. As described above, the lubricant 424 may be sealed within the bearing housing 420 by a seal 426. The seal 426 is configured to retain the lubricant within the bearing housing 420 and prevent the drilling mud 404 from entering the bearing housing 420. The seal 426 is configured to maintain this seal even during rotation of the rotor shaft 418 relative to the seal 426. Additionally, a torsion spring 428 is shown that is operably connected to the rotor shaft 418 to ensure that the rotor shaft 418 (and attached rotor 408) will return to a specific and predefined position when the motor 414 is turned off (i.e., the open position of the flow path defined when the stator flow passage 410 is aligned with the rotor flow passage 412).

[0074] According to some embodiments, the pulser assembly can be operated to perform sinusoidal or substantially sinusoidal oscillations of the rotor 408 relative to the stator 406. Furthermore, according to some embodiments, the pulser assembly 400 can be configured for a variety of different modulation schemes. For example, but not limited to, a processor or other controller can be configured to drive the operation of the pulser assembly to transmit data using any of a number of encoding schemes, including but not limited to amplitude shift keying (ASK), frequency shift keying (FSK), pulse position modulation (PPM), quadrature phase shift keying (QPSK), or phase shift keying (PSK), or combinations of these techniques. Furthermore, in some embodiments, the amplitude of the generated signal can be controlled or adjusted through controlled operation of the pulser assembly. For example, different amounts of blocking or angular rotation can be used to generate different pulse amplitudes. That is, in some embodiments, the maximum rotation angles α1, α2 (off state) can be controlled and adjusted to enable the generation of pressure pulses of different amplitudes. The specific modulation technique, oscillation mode, amplitude, etc. can be controlled by a controller operably connected to the motor of the pulser assembly. The controller may be configured to receive a downlink from the surface with instructions for a particular type of operation, such as amplitude, signal strength, modulation scheme, oscillation mode, maximum angle, oscillation frequency, etc. Such a downlink may be used to change specific operating parameters of the pulser assembly.

[0075] According to the embodiments of the present disclosure (e.g., Figure 3), the minimum number of blocking elements is one, which can be rotated to selectively block the flow path of the fluid through the pulser assembly. The number of blocking elements can be based in part on the desired rotation angle range α1, α2 for blocking. For example, in one non-limiting embodiment, a relatively high number of blocking elements can result in smaller oscillation angles α1, α2. In addition, the relative angular dimensions of the blocking elements relative to the opening of the stator flow channel can be configured for desired operation. For example, in the various illustrations shown herein, the blocking elements can have approximately the same size and shape as the opening of the corresponding stator flow channel that is selectively blocked by the blocking elements. However, in other embodiments, the blocking elements can be larger or smaller than the opening of the stator flow channel. That is, in some non-limiting embodiments, the angular arc or range (angular dimension) of the blocking element can be larger than the angular arc or range of the corresponding opening of the stator flow channel. In the same way, the radial dimension of the blocking element can be smaller or larger than the radial dimension of the stator flow channel, the term "radial" referring to the direction perpendicular to the axis of the rotor shaft.

[0076] In some embodiments, the pulser assembly of the present disclosure may include various additional components. For example, the pulser assembly may include a controller, a processor, sensors, feedback elements, etc., which may be operably connected to and / or in communication with the pulser assembly's controller. Such electronic components and parts may be used to operate the pulser assembly described herein. For example, one or more pressure sensors may be mounted at locations above and below the pulser assembly to monitor pressure upstream and downstream of the pulser assembly. Such pressure sensors may be configured with sensing surfaces exposed to the fluid in the drill string bore. The pressure sensors may be powered by an electronics module, as described above, and may be configured to receive surface-transmitted pressure pulses. The processor and / or circuitry in such an electronics module may be programmed to change data encoding parameters based on the received surface-transmitted pulses. The encoding parameters may include the type of encoding scheme, baseline pulse amplitude, baseline frequency, maximum angle, or other parameters that affect data encoding.

[0077] A pressure sensor mounted above the pulser assembly can be used to measure the pressure differential between the open and closed positions of the flow path. As the fluid flow rate changes (flow rate changes), the pressure differential between the open and closed positions can change, which can affect the pressure pulse decoding at the surface. This is because the amplitude of the received pressure signal varies with the pressure differential. For example, the desired pressure in the fluid column in the bore of the drill string above the pulser assembly may be 50 bar in the open position and 20 bar in the closed position of the flow path. This configuration provides a pressure differential of 30 bar. If the flow rate of the fluid pumped through the bore of the drill string changes during downhole operations, the pressure differential may also change. Based on the change in the pressure differential measured by the pressure sensor above the pulser assembly, the pulser assembly controller can change pulser assembly parameters, such as the base frequency or maximum angle to be adjusted, to once again achieve a pressure differential of 30 bar. A pressure sensor below the pulser assembly allows for measurement of the pressure differential above and below the pulser assembly.

[0078] Now turn Figures 5A to 5C , shows a series of schematic diagrams of the operation of a pulser assembly 500 according to one embodiment of the present disclosure. The pulser assembly 500 includes a stator 502 and a rotor 504 rotatable relative to the stator 502. The fluid flow 501 is Figures 5A to 5B Thus, the fluid stream 501 flows into the pulser assembly 500 from the ground toward the pulser assembly 500 (as indicated by the arrows of the fluid stream 501). The fluid stream 501 will flow into the stator 502 through one or more flow paths 512 defined by the stator flow channels 506 and toward the rotor 504. In some embodiments, the rotor 504 is positioned downstream of the stator 502 (e.g., as shown in FIG. Figures 5A to 5C ). However, in other embodiments, the rotor may be arranged upstream of the stator, or the rotor may be arranged between the two stators. The rotational movement of the rotor 504 may be driven by a motor, as described above. The stator 502 includes a plurality of stator flow channels 506, and the rotor 504 includes a plurality of rotor flow channels 508 defined between blocking elements 510. When the rotor flow channels 508 are aligned with the stator flow channels 506, a flow path 512 through the pulser assembly 500 is defined. When the blocking elements 510 are aligned with the stator flow channels 506, fluid flow through the flow path 512 is blocked (completely or partially). Even if the flow path 512 is completely blocked, a secondary flow path remains around the blocking elements 510, thereby allowing flow to bypass the rotor, but at a higher pressure than if it were less blocked.

[0079] Figures 5A to 5C An orientation sequence is shown as the rotor 504 rotates relative to the stator 502 to illustrate the orientation of the blocking element 510 relative to the stator flow channel 506 during oscillation of the rotor 504 . Figure 5AA sequence of a first open to closed sequence (orientations (a)-(d)) is shown, wherein a first open orientation is shown at orientation (a) and a first closed orientation is shown at orientation (d). Figure 5B The sequence of transitions from a first closed orientation (d) to a second open orientation (g) is shown. Figure 5C The transition sequence from the second open orientation (g) to the second closed orientation (k) is shown. Figures 5A to 5C This is done with reference to the particular blocking element 514 as it rotates relative to the first stator flow passage 516 and the second stator flow passage 518 .

[0080] Orientation (a) shows an open position, in which rotor flow channel 508 is aligned with stator flow channel 506, and thus flow path 512 is at maximum flow opening. In this orientation, blocking element 514 does not block flow through any flow path 512 and is aligned with a portion of stator 502. However, as the process transitions from orientation (a) to orientation (b) to orientation (c), rotor 504 rotates relative to stator 502, causing blocking element 514 to begin blocking or overlapping first stator flow channel 516. It should be understood that other blocking elements 510 will block flow through other stator flow channels 506, including second stator flow channel 518. However, this description will focus solely on blocking element 514 as it blocks flow through first and second stator flow channels 516, 518. Consequently, blocking element 514 will restrict or block flow through flow path 512, which passes through first stator flow channel 516. In orientation (d), the blocking element 514 is aligned with the first stator flow channel 516 (maximum angular position), and thus the flow path 512 through the first stator flow channel 516 is maximally obstructed (e.g., substantially blocked), thereby creating a high pressure (first maximum obstruction) in the flow upstream of the rotor 504. In orientation (d), the rotational speed of the rotor 504 is zero.

[0081] Go to Figure 5B In the sequence shown, the direction of rotation of the rotor 504 is reversed, and the orientation of the rotor 504 relative to the stator 502 is reversed. As shown, the blocking element 514 transitions from orientation (e) to orientation (g), and thus transitions from a maximum blocking position (orientation (d)) back to a maximum open position of orientation (g).

[0082] The rotational motion of the rotor 504 will continue beyond the center orientation (orientation (g)), and the blocking element 514 will travel beyond the open position to a second (opposite) maximum angular position (at zero speed and maximum obstruction). That is, the blocking element 514 will continue to oscillate to block flow through the second stator flow channel 518 (orientations (h) to (k)), as shown. Figure 5C As shown. Thus, the rotational aspect of the embodiments of the present disclosure is a transition from an open position at the start (orientation (a)) to a first closed position (orientation (d)), reversing the direction of rotation, through an open position (orientation (g)), and to a second closed position opposite the first closed position (orientation (k)), and then repeating in an oscillatory manner. Thus, assuming sinusoidal movement, during operation (open position) a maximum rotational speed will occur in orientations (a) and (g), and a minimum rotational speed (i.e., zero) will occur in the maximum closed position (orientations (d) and (k)). The reversal point of the rotor oscillation will occur at the maximum closed position.

[0083] As described above, as provided in the embodiments of the present disclosure, when using the closed-to-closed movement of the blocking element, a sinusoidal drive of the rotor may be recommended to save energy. Under such control, as discussed, the minimum rotational speed is at the extreme of the closed state, and the maximum rotational speed is at the extreme of the fully open state. The cyclical pattern of oscillation according to the embodiments of the present disclosure is therefore between the short open state between the closed state and the closed state, wherein the neutral torque free state is located in the middle (open) position. This allows the use of a torsion spring (e.g., spring 428) operably connected to the rotor shaft and the attached rotor. The torsion spring returns the rotor to a specific and predefined position or orientation when the motor is turned off. That is, when the motor is deactivated or turned off, the rotor will return to a position or orientation relative to the stator that has a maximum open flow path through the pulser assembly. In addition, such a configuration allows the use of a torsional resonant spring-mass system that can operate near or at the desired operating frequency of the pulser assembly.

[0084] Now turn 6A to 6D , shows a schematic graph representing the oscillatory operation of a pulser assembly according to one embodiment of the present disclosure. Figure 6A The graph 600 shown in FIG. 6 represents the angular position of the rotor relative to the stator of the pulser assembly. Figure 6B The graph 602 shown in FIG. 6 represents a graph of the pressure of the drilling mud within or above the pulser assembly. Figure 6C Graph 604 shown in FIG. 6 represents the power consumption of the electric motor driving the rotor. Figure 6D Graph 606 shown in FIG. 6 is a schematic graph of the current drawn by the motor.

[0085] exist Figure 6A In the embodiment, when the position of the rotor is at the minimum angular position (α0) (the intermediate position), the flow path through the pulser assembly will be fully open, and at the maximum angular positions α1 and α2, the flow path through the pulser assembly may be partially or fully blocked by a blocking element that covers or otherwise blocks the corresponding stator flow channel, as shown and described above.

[0086] In graphs 600, 602, time t0 represents the position of the rotor in an intermediate position. This can be a stationary position of the rotor, such as a power state shut down with the drive motor shut down, or it can be an intermediate position during a cycle of the rotor. As shown in graphs 600, 602, time t0 is equal to 0.125s. The rotor will rotate to a first rotational direction toward the first closed position of the close-to-close sequence. At time 0.25s (labeled as time t1), the angular position of the rotor is at a first maximum closed position (e.g., a first blocking angle α1, as described above), and the blocking element will block the stator flow channel to prevent or maximally restrict flow through the flow path of the pulser assembly. In one non-limiting example, the first rotational direction of the rotor can be clockwise, and the blocking element will close the flow path. At time t1, the pressure is at a maximum, such as Figure 6B As shown (first pulse). At time t1, this position and pressure mark the beginning of the closed-to-closed pulse sequence. In this example, the actuation frequency may be 2 Hz. That is, at time t1, the pulser assembly is in the maximum closed position and the rotor is rotating at zero angular velocity (the reversal point), thus creating the first high pressure state at time t1. In other words, the pressure during the rotor cycle is at its maximum at time t1.

[0087] Starting at time t1, the rotor will reverse direction at time t2 (time 0.375s) and proceed counterclockwise through the open position or state (neutral position). At time t2, the rotor will rotate at maximum speed, and the pressure will again be at its lowest value during the rotor cycle. However, at time t3 (time 0.5s), the rotor will continue to rotate counterclockwise in a second rotational direction to the second maximum angular position of rotor α1, opposite the rotor's first maximum angular position relative to the neutral position. This rotation from time t1 (closed) to time t3 (closed) represents half a rotor cycle. At time t3, the rotor is at the second reversal point and the second maximum closed position. The second reversal point is similar to the first reversal point, with zero angular velocity and a second high-pressure state (second pulse). The rotor will then reverse direction (return to clockwise rotation) and pass through the center (position 0 or neutral position, for example, as shown at time t0) and reach the first extreme reversal position again. Therefore, at time t4 (time 0.625s), the pulser assembly opens and achieves low pressure, but at the rotor's highest / maximum rotational speed. The rotor will return to the maximum closed position at time t5 (time 0.75s) and reach zero rotational speed again to reverse direction and complete a closed-to-closed cycle.

[0088] Figure 6Cis a schematic graph illustrating the power consumption of the electric motor driving the rotor. Power consumption is at its maximum at times t1 and t3 when the rotor is in its first and second most closed positions and the pressure is at its maximum. Power consumption is at its minimum at times t2 and t4 when the rotor is in its intermediate position and the pressure is at its minimum. Figure 6D is a schematic graph of the current drawn by the motor. When the rotor passes through the intermediate position and the pressure is at a minimum, the current is zero at times t2 and t4. When the rotor is in the first and second maximum closed positions, the current is at a maximum at times t1 and t3. As the direction of rotation of the rotor (and motor) changes to the opposite direction, the current polarity changes between the first (t1) and second (t3) maximum closed positions.

[0089] Figure 7 FIG7 is a schematic graph 700 illustrating the relationship between angular position and pressure in the mud column above the pulser assembly. On the left side of graph 700, the rotor is in an angular position that allows fluid flow (an open position or nearly an open position). As the angle increases (along the x-axis), at least one blocking element of the rotor increasingly closes or blocks the fluid passage, causing the pressure in the mud column to increase. As shown in the figure, the relationship is nonlinear. Due to this nonlinear relationship, the pressure curve produced by the existing system has a relatively high crest factor. The crest factor is a parameter of the waveform that represents the ratio of the peak value to the effective value. In other words, the crest factor indicates the extreme degree of the peak of the waveform. The relatively high crest factor (and extreme peaks) of the existing system reduces the effective signal transmission strength.

[0090] The disclosed embodiments can optimize the pressure pulse by creating a pressure profile that concentrates the energy on the fundamental frequency (carrier frequency) and contains only a few higher harmonics with relatively low amplitude in the transmitted signal. Thus, the effective signal strength can be maximized. For example, in a pressure profile (e.g., Figure 6B ) can be seen that the sinusoidal pressure curve is generated by a sinusoidal moving input (e.g., at the rotor). That is, the motor of the pulser assembly can be driven using a sinusoidal moving input to drive the oscillation of the rotor. It should be noted that due to the fact that two pressure cycles are generated in one mechanical cycle (one rotor cycle), the frequency of the pulsed pressure is twice the mechanical frequency. In addition, the minimum mechanical input power to generate the signal (e.g., torsion spring, no gears, larger rotation angles at lower angular velocities) can be achieved by the embodiments of the present disclosure. This may be useful for high carrier frequencies (pressure fluctuations), such as above, for example, 10 Hz (5 Hz mechanical rotor oscillation frequency). This minimization can be achieved by driving the oscillatory movement of the rotor by a sinusoidal drive performed by the motor. Therefore, according to some non-limiting embodiments, a sinusoidal input is selected for the oscillatory drive of the rotor relative to the stator.

[0091] In existing configurations, such as shown and described in U.S. Patent No. 7,280,432, which is incorporated herein by reference, using a sinusoidal relationship between angular position and time to minimize mechanical energy requirements results in a less than ideal pressure profile. Figure 8A As shown, the graph 800 represents a graph similar to Figure 6B The pressure sequence of graph 800 deviates from a single frequency sinusoidal pattern and therefore produces a weaker pressure transmission signal (signal power is lost in the higher frequency content, higher harmonics). It should also be noted that for Figures 6A to 6B At the same pulse actuation frequency (and peak pressure) used in [1], the position frequency of existing systems is twice that of the system according to the present disclosure, but the amplitude is half. Various existing systems have attempted to address this shortcoming by using unique valve geometries (e.g., U.S. Patent No. 4,847,815), but such systems also suffer from other disadvantages, such as an unfavorable torque-to-close angle relationship and a reduced cross-section in the open position. Other solutions may incorporate an axial offset between the stator and rotor.

[0092] Additionally, some existing configurations operate using on-to-on oscillations (as opposed to current off-to-off oscillations). Figure 8B The pressure curve 802 for open to open operation is shown with a very large crest factor, with significant pressure peaks (spikes). The spikes occur as the vanes or other obstructing elements pass through the stator flow passage at the highest speed (between the two open positions). That is, the period of the closed state is very short, while the open state is where the oscillation changes direction. This results in Figure 8B Pressure graph 802 is shown.

[0093] Although this open-to-open operation produces a similar pressure drop, the transmitted signal strength is significantly reduced as a result. This is observed when using a sinusoidal angle positioning versus time and the same relationship of pressure versus closing angle as described above for Figure 7 Explained. Figure 8B The steep pressure spike shown can be explained by the high angular velocity movement in the closed position, rather than the relatively long exposure in the open position during the cycle reversal (rotor cycle). Figure 7 ), the time period of the pulse pressure is very short and results in a spike-like pulse. As noted, compared to the pressure signal of the embodiment of the present disclosure ( Figure 6B , graph 602), the crest factor in graph 802 is much higher. In addition, the open-to-open operation may cause signal attenuation and distortion, reduced signal strength, etc.

[0094] Such an open-to-open system may be suitable for baseband transmission at relatively low frequencies, preferably with a stationary position in the closed valve state, thereby forming a plateau at high pressure. Therefore, the open-to-open sequence must be stopped at an intermediate position, where the highest speed would typically be for a sinusoidal drive input. Consequently, in the case of non-sinusoidal inputs and non-sinusoidal pressure pulse generation, the system would be less suitable for the high-speed mud pulse telemetry systems enabled by embodiments of the present disclosure. For example, existing open-to-open systems are typically suitable for operation up to 2 Hz, while the closed-to-close operation described herein enables operation up to 50 Hz.

[0095] The pulser assembly and operation of the present invention overcomes these disadvantages while also improving the efficiency of signal transmission (e.g., sinusoidal operation and pressure transmission). That is, by employing an off-to-off oscillating operation, a sinusoidal pressure pulse with a relatively low crest factor can be achieved. A low crest factor and a smooth sine wave (compared to Figure 6B and Figure 8 ) provide an effective pressure signal to be generated at the surface and thus extracted.

[0096] As mentioned above, and as Figure 4 As shown, a spring (e.g., torsion spring 428) can be implemented within the pulser assembly of the present disclosure. The spring can be a torsion spring with a biasing force that ensures that when the motor is turned off, the rotor does not block the stator flow passage, so the flow path will remain in a default or basic (neutral) position. The spring (e.g., Figure 4 The torsion spring 428 shown in FIG can be configured to ensure that the rotor is aligned with the stator and thus open a maximum flow path through the pulser assembly. As will be appreciated by those skilled in the art, a torsion spring can be used to reduce inertial torque and fluid torque. However, an advantage provided by embodiments of the present disclosure is the open state (open flow path) of the pulser assembly when the motor is off or powered off. In some embodiments, the spring can be attached to the rotor shaft and can be a torsion bar (such as Figure 4 However, other designs may use coil springs, magnetic springs, etc.

[0097] As mentioned above, and as Figure 4 As shown, seals (e.g., seal 426) may be implemented within the pulser assembly of the present disclosure. The seal(s) may be in the form of flexible bellows and provide sealing and pressure compensation, particularly for fluid lubricant within the bearing housing and drilling mud external to the bearing housing.

[0098] Reference again Figure 4The bearing housing 420 is filled with a suitable lubricant 424 to lubricate the bearing 422 and utilize the downhole pressure of the drilling mud 404 to pressure-compensate the inner cavity of the bearing housing 420. In some embodiments, the bearing 422 may be a typical anti-friction bearing known in the art and will not be described further. In some embodiments, the seal 426 is a flexible bellows seal directly coupled to the rotor shaft 418 and the bearing housing 420. The seal 426 hermetically seals the lubricant within the bearing housing 420. In such a configuration, angular movement (i.e., oscillatory rotation) of the rotor shaft 418 causes the flexible material of the bellows seal 426 to twist. This twisting can accommodate angular movement while maintaining a seal. As will be understood by those skilled in the art, the flexible bellows material may be an elastomeric material, a fiber-reinforced elastomeric material, or other suitable material. In some configurations, it may be desirable to maintain relatively small angular rotation so that the bellows material is not overly stressed by the twisting movement (thus allowing for the use of a relatively large number of blades / blocking elements). In some embodiments, the seal can be formed by an elastomeric rotary shaft seal, a mechanical face seal, a fluid barrier seal, or other similar sealing configurations, as known in the art. In some embodiments, the seal can be implemented using an airtight sealing assembly (including but not limited to a magnetic clutch device) that enables motion to be transferred through the barrier by means of magnetic torque transfer.

[0099] Now turn Figure 9 , shows a schematic diagram of a pulser assembly 900 according to one embodiment of the present disclosure. The pulser assembly 900 can operate similarly to that described above, having an open default or de-energized position and a driven oscillation between two closed positions. The pulser assembly 900 includes a tool housing 902 through which drilling mud can flow. Disposed within the tool housing 902 is a stator 904 and a rotor 906 disposed relative to the stator 904. In this exemplary embodiment, the stator 904 defines a plurality of stator flow channels, and the rotor includes an equal number of rotor flow channels defined between blocking elements. As described above, when the rotor flow channels are aligned with the stator flow channels, a flow path can be defined that allows drilling mud to flow through the pulser assembly 900. In operation, the rotor 906 can be rotatably driven by a motor and can include one or more blocking elements that will block (partially or completely) the stator flow channels to reduce or prevent drilling mud from flowing through the pulser assembly 900.

[0100] Rotor shaft 908 is configured to be driven by a motor and is operably connected to rotor 906. The rotor shaft is at least partially housed within a bearing housing 910, which contains one or more bearings that support rotor shaft 908. Bearing housing 910 is filled with lubricant to facilitate rotation of rotor shaft 908 within bearing housing 910. A seal 912 is disposed between bearing housing 910 and rotor shaft 908. Seal 912 may be a bellows seal that is fixedly attached to bearing housing 910 and sealingly engages a surface of rotor shaft 908. Seal 912 may be made of an elastomer or other flexible material that allows rotor shaft 908 to rotate relative to seal 912 while maintaining sealing contact therebetween. Seal 912 provides a dual rotation angle compared to conventional bellows seals.

[0101] Now turn Figure 10 , shows a schematic pressure graph 1000 comparing different oscillating systems. The oscillating system shown in the pressure graph 1000 uses a similar sinusoidal drive input (such as Figure 6A ) and consider the relationship between pressure and angle (as shown in Figure 7 ). Pressure graph 1000 includes a closed-to-close oscillating system (disclosed herein) as shown by pressure graph 1002, a semi-oscillating system (prior art) as shown by pressure graph 1004, and an open-to-open oscillating system (prior art) as shown by pressure graph 1006.

[0102] The close-to-close pressure curve 1002 most closely resembles a clean, sinusoidal pressure curve. Therefore, only a few relatively low-amplitude higher harmonics are required to reconstruct the signal at the surface. The frequency content of this pressure curve 1002 remains low, with most of the energy at the fundamental frequency and, therefore, unaffected by bandwidth limitations. Furthermore, the crest factor closely approximates that of a sine function. Therefore, signal transmission is nearly optimal. Due to the relatively low (ideally, none) energy in the several higher harmonics, most (ideally, all) of the pressure energy (hydraulic energy) generated by the pulser assembly is concentrated at the carrier frequency (the fundamental frequency) of the pressure signal. With existing systems, as the pressure curve deviates from a sinusoidal shape, energy is trapped in the higher harmonics. Because higher-frequency pressure waves are more damped as they travel through the mud column to the surface, energy is lost, making it more difficult to detect the pressure signal at the surface and resulting in lower decoding quality.

[0103] In contrast, the semi-oscillatory system illustrated by pressure curve 1004 has a pressure signal that is not a clean sinusoidal pulse (the peaks are sharper and the intervals between peaks are longer due to the extended low-pressure period). Therefore, reconstruction at the surface requires the use of additional higher-order harmonics compared to the harmonics required to reconstruct pressure curve 1002. The harmonics will decay more slowly than in pressure curve 1002. The frequency content of the higher frequencies is no longer negligible. That is, the overall energy content is not concentrated solely at the fundamental frequency. In order to reconstruct the signal from pressure curve 1004, the higher-order harmonics require some bandwidth. This results in a higher crest factor for pressure curve 1004 than for a clean sinusoidal signal (e.g., pressure curve 1002).

[0104] Pressure curve 1006 for open-to-open oscillatory operation does not approximate a sinusoidal shape. Compared to the other pressure curves 1002 and 1004, this pressure curve 1006 has a high crest factor. Reconstructing the signal from pressure curve 1006 requires significant high-order harmonics with high amplitudes. The bandwidth required for reconstruction is significant, and the high-order harmonic content dominates the signal. Furthermore, this results in noise across a wide frequency range, resulting in poor signal transmission quality.

[0105] Now turn Figures 11A to 11C , shows a schematic diagram of a rotor 1100 to be used with a pulser assembly according to one embodiment of the present disclosure. The rotor 1100 is configured to reduce the overall power requirements of the pulse pressure generation. In operation, a hydraulic torque (fluid torque) is generated by the flowing fluid (drilling mud). The hydraulic torque curve can reach high torque values, especially at high flow rates, high fluid density and when it is towards the closed position (i.e., the blocking element blocks the flow path). In addition, the fluid torque can exhibit unstable behavior with high changes in torque value even with small changes in the position of the relevant components. This unstable torque (e.g., Figure 13A Galloping instability (as shown) may result in approaching the closed position.

[0106] To address this instability, the rotor 1100 is configured to achieve a more stable opening torque when approaching the closed position. The rotor 1100 includes a plurality of blocking elements 1102 distributed around and extending from a hub 1104. The hub 1104 can be configured to be operably connected to the rotor shaft of the pulser assembly to achieve driven rotation of the rotor 1100. Adjacent blocking elements 1102 define rotor flow channels 1106 through which drilling mud can pass. As described above, the size and shape of the blocking elements 1102 are set to selectively block or prevent fluid from flowing through the stator flow channels.

[0107] Blocking element 1102 is configured with a chamfered sidewall 1108 or edge. A sidewall refers to the side of the rotor that defines the rotor flow channel. The angle of chamfered sidewall 1108 is set so that the upstream side 1103 of rotor flow channel 1106 has a larger cross-section than the downstream side 1105 of rotor flow channel 1106. In other words, rotor flow channel 1106 has a narrowing geometry along the flow direction through rotor flow channel 1106. Chamfered sidewall 1108 provides an upstream-facing chamfer or surface (i.e., facing the flowing fluid) to deflect the direction of fluid flow and generate an opening torque. This is particularly useful when rotor 1100 is nearing a closed position (i.e., blocking element 1102 is aligned with or substantially covers the stator flow channel). In the open position of the flow path through the stator and rotor, blocking element 1102 does not block the stator flow channel and therefore has no effect on rotor 1100 (i.e., chamfered sidewall 1108 is not exposed to the flowing fluid). However, as the rotor 1100 rotates toward the closed position, the chamfer opening torque effect will increase. The size, angle, and other geometry of the chamfered sidewall 1108 can result in establishing a desired torque curve. In some embodiments, the chamfer can include a bevel, radius, or groove.

[0108] Figure 11B A side view of the obstruction element 1102 of the rotor 1100 is shown, such as along Figure 11A As shown in view BB in. Figure 11C A cross-sectional view of the obstruction element 1102 of the rotor 1100 is shown, such as along Figure 11A As shown in view CC in Figure 11B As shown, the flow direction F d To the right on the page, the obstruction element 1102 thus has an upstream face 1110 located at the upstream end of the obstruction element 1102. Starting from the upstream face 1110, the obstruction element 1102 has a chamfer depth D c . Chamfer depth D c The chamfered side wall 1108 is formed from the upstream surface 1110 along the flow direction F d In addition, if Figure 11C As shown, the chamfered sidewall 1108 has a chamfer angle β. That is, the chamfered sidewall 1108 is along the flow direction F d According to some non-limiting embodiments, the chamfer angle β may be between about 5° and about 45°, and the chamfer depth D c Between about 2 mm and about 10 mm. These are merely exemplary dimensions of the barrier element and its chamfered sidewalls according to some exemplary embodiments of the present disclosure and are not intended to be limiting.

[0109] Now turn 12A to 12D, a schematic diagram illustrating the operation of a pulser assembly 1200 according to one embodiment of the present disclosure is shown. The pulser assembly 1200 includes a stator 1202 and a rotor 1204, similar to those shown and described above. The rotor 1204 includes a plurality of blocking elements 1206, wherein each blocking element 1206 has a chamfered sidewall 1208 (e.g., as shown in FIG. 1 ). Figures 11A to 11C shown and described). 12A to 12D , the flow direction 1210 is to the right on the page, such that the rotor 1204 is disposed downstream of the stator 1202. Thus, as shown, the chamfered sidewall 1208 faces upstream and can be directly impacted and acted upon by the fluid flow.

[0110] Figure 12A The pulser assembly 1200 is shown in a starting state (orientation (a)) in which the blocking element 1206 does not block or otherwise obstruct flow through the stator flow channels 1212 , 1214 . Figure 12B A sequence of orientations (b) through (d) is shown, illustrating the transition or partial oscillation of the blocking element 1206 as it rotates to block flow through the first stator flow channel 1212. That is, orientations (b) through (d) illustrate the transition from an open to a closed (first closed) state of the pulser assembly 1200. As the blocking element 1206 rotates, the chamfered sidewalls are exposed to fluid flow, and this fluid flow exerts a normal force (i.e., an opening torque) on the ground surface that is opposite to the direction of rotation (i.e., in the direction that moves the blocking element 1206 back to the open state of the first stator flow channel 1212). Orientation (d) represents the maximum range of rotation of the blocking element 1206 as it blocks flow through the first stator flow channel 1212. In orientation (d), the rotational speed of the rotor 1204 is zero, and a change in rotational direction occurs, as described above.

[0111] Figure 12C Orientations (e) to (g) are shown, representing a change in the direction of rotation of the blocking element 1206 due in part to a change in rotor rotation and assisted by the force exerted by fluid flow against the chamfered sidewall 1208 (opening torque). Figure 12C Orientation (f) of FIG. 1 shows the blocking element 1206 returning to the open state of the first stator flow channel 1212, wherein flow therethrough is unimpeded. Since this is during oscillation of the pulser assembly 1200, the blocking element 1206 rotates through this position at maximum rotational speed. Orientation (g) shows the blocking element 1206 continuing to travel in the rotational direction of the sequence of orientations (e) through (g), such that the blocking element 1206 travels to a position blocking the second stator flow channel 1214. The second closed state is represented by FIG. Figure 12DA sequence of orientations (h) through (j) is shown, with orientation (j) representing a second, closed state of the pulser assembly 1200. In this position, the rotational speed of the rotor is zero, and the fluid flow will exert a force (opening torque) on the blocking element 1206 at the chamfered sidewall 1208, causing the blocking element 1206 to reverse direction and return toward the open state shown in orientations (a) or (f).

[0112] As detailed above and as 12A to 12D As shown, the blocking element may be larger than the opening of the stator flow channel. That is, in some non-limiting embodiments, the angular arc or range of the blocking element may be larger than the angular arc or range of the corresponding opening of the corresponding stator flow channel. 12B to 12D In the operating cycle shown, the larger angle rotor arc supports the function of the chamfered sidewall 1208. Although both sides of the rotor blocking element 1206 may have chamfered sidewalls, the chamfered sidewall on the closed side of the rotor provides an opening torque that increases toward the blocking position. During such operation, the other chamfered sidewall is hidden behind the stator blocking element, so the hydraulic torque generated is significantly reduced or not generated. In some embodiments, if the circumferential (arc) width of the blocking element is similar to the stator flow channel opening arc, both of the blocking element chamfered sidewalls will be effective in the fully blocked (or near fully blocked) position. Therefore, in some such configurations, when both chamfered sidewalls are exposed simultaneously, the opening torque may be effectively offset or may be unstable (i.e., the effect of the two chamfered sidewalls may result in a neutral torque that is offset when both sides are exposed equally at the same time). For example, in certain circumstances and at certain flow rates and fluid velocities, a situation such as Figure 13A The fluid torque instability shown is shown. Therefore, a blocking element having an arc width greater than the stator flow channel opening can provide significant advantages compared to alternative configurations. In one embodiment, when the pulser assembly is in the closed state, the chamfered sidewall on the closed side can be hidden behind the stator blocking element. That is, the chamfered sidewall can completely disappear behind the stator blocking element. In another embodiment, when the pulser assembly is in the closed state, the chamfered sidewall on the closed side can remain at least partially active. That is, the chamfered sidewall can be at least partially exposed in the closed state of the pulser assembly.

[0113] In some embodiments, the chamfer may extend from the upstream face of the rotor to the downstream face of the rotor. In other embodiments, the chamfer may extend only over a portion of the sidewall between the upstream and downstream faces of the rotor. Thus, the chamfer may begin on the upstream face but not extend to the downstream face, or the chamfer may begin at a distance from the upstream face and end at a distance from the downstream face. A chamfer that does not extend to the downstream face results in greater mechanical stability and prevents material erosion because the chamfer does not end at a small edge of the downstream face.

[0114] Hydraulic torque may be affected by various factors and elements related to fluid flow and the arrangement of the elements of the pulser assembly. For example, but not limited to, some factors related to the pulser assembly may include: the rotational position of the rotor and / or the blocking element, the axial gap distance between the stator and the rotor, the radial clearance between the outer diameter of the blocking element (or rotor edge) and the interior of the tool housing, the blocking element width, the chamfer design and size, the back (downstream) geometry of the blocking element, any reinforcement structures, the rotor hub diameter, the number of rotor flow channels (and the flow path through the pulser assembly), the outer diameter of the pulser assembly, and the effective lever arm of the blocking element. In addition, some exemplary factors related to the fluid passing through the pulser assembly may include, but are not limited to, the pressure drop across the rotor, the flow rate of the drilling mud, and the fluid density.

[0115] Go to 13A to 13B , a schematic graph shows Figure 13A The graph 1300 of the rotor with straight sidewalls (ie, no chamfers) is compared to Figure 13B Graph 1300 illustrates the difference between the rotors with chamfered sidewalls and the rotors with chamfered sidewalls in graph 1302. Graph 1300 illustrates the instability of the torque as the angular position of the rotor without such chamfered sidewalls increases (i.e., toward the closed position). In contrast, graph 1302 illustrates the relatively smooth torque curve resulting from the chamfered sidewalls incorporated into the rotor (e.g., as Figures 11A to 11C and shown in Figure 12).

[0116] Embodiment 1: A method for generating pulses in a drilling fluid, the method comprising: driving a rotor to rotate relative to a stator of a pulser assembly in an oscillating manner, wherein the pulser assembly comprises a tool housing arranged along a drill string, and the stator and the rotor are arranged within the tool housing, wherein the stator comprises at least one stator flow channel to allow drilling fluid to flow therethrough, and the rotor comprises at least one rotor flow channel to allow drilling fluid to flow therethrough, and comprises at least one blocking element configured to selectively block fluid flow through the at least one stator flow channel, wherein the oscillating manner comprises: rotating the at least one blocking element from an intermediate position to a first blocking angular position such that the at least one blocking element is energized by the at least one stator. a first selective blocking of a flow channel, wherein the intermediate position is defined by minimal blocking of flow through the at least one stator flow channel by the at least one blocking element; and rotating the at least one blocking element from the first blocked angular position to a second blocked angular position such that second selective blocking of the at least one stator flow channel by the at least one blocking element occurs, wherein rotation of the at least one blocking element selectively blocks the at least one stator flow channel when drilling fluid flows through the drill string to generate pressure pulses in the drilling fluid, and wherein the oscillatory mode is an oscillation of the at least one blocking element between the first blocked angular position and the second blocked angular position such that the direction of rotation of the rotor changes at the first blocked angular position and the second blocked angular position.

[0117] Embodiment 2: The method according to any of the preceding embodiments, wherein the rotation of the at least one blocking element from the first blocking angular position to the second blocking angular position comprises passing through the intermediate position.

[0118] Embodiment 3: The method according to any of the preceding embodiments, wherein the maximum rotational speed of the rotor is reached at the intermediate position.

[0119] Embodiment 4: The method according to any of the preceding embodiments, wherein a minimum rotational speed of the rotor is reached at the first blocked angular position and the second blocked angular position.

[0120] Embodiment 5: The method of any of the preceding embodiments, further comprising biasing the rotor to maintain the at least one blocking element substantially in the intermediate position such that the at least one stator flow channel is open to passage of the drilling fluid.

[0121] Embodiment 6: The method according to any of the preceding embodiments, further comprising driving the rotation of the rotor to overcome the biasing force of the biasing element, thereby driving the at least one blocking element toward at least one of the first blocking angular position and the second blocking angular position.

[0122] Embodiment 7: The method according to any of the preceding embodiments, wherein the at least one barrier element comprises a chamfered sidewall.

[0123] Embodiment 8: The method of any one of the preceding embodiments, wherein the chamfered sidewall extends from the upstream face of the at least one barrier element to a chamfer depth.

[0124] Embodiment 9: The method according to any of the preceding embodiments, wherein the chamfer depth is between about 2 mm and about 10 mm.

[0125] Embodiment 10: The method of any one of the preceding embodiments, wherein the chamfered sidewall extends from the upstream face of the at least one barrier element at a chamfered angle.

[0126] Embodiment 11: The method according to any of the preceding embodiments, wherein the chamfer angle is between about 5° and about 45°.

[0127] Embodiment 12: According to the method described in any of the preceding embodiments, the method also includes using at least one of amplitude shift keying (ASK), frequency shift keying (FSK), pulse position modulation (PPM), quadrature phase shift keying (QPSK) and phase shift keying (PSK) to transmit downhole information from the pulser assembly.

[0128] Embodiment 13: The method according to any of the preceding embodiments, wherein the pressure pulse has a sinusoidal pressure curve.

[0129] Embodiment 14: The method according to any one of the preceding embodiments, further comprising adjusting at least one of a first blocking angle at the first blocking angle position and a second blocking angle at the second blocking angle position to adjust an amplitude of the pressure pulse.

[0130] Embodiment 15: The method according to any of the preceding embodiments, wherein the pulser assembly comprises a single stator flow channel and a single blocking element.

[0131] Embodiment 16: The method of any preceding embodiment, further comprising receiving a downlink comprising operating instructions for driving rotation of the rotor.

[0132] Embodiment 17: The method according to any of the preceding embodiments, wherein the rotor is arranged downstream of the stator.

[0133] Embodiment 18: The method of any one of the preceding embodiments, wherein the oscillating means is driven by one of a reversible brushless DC motor, a servo motor, or a stepper motor.

[0134] Embodiment 19: The method according to any of the preceding embodiments, wherein the pulser assembly comprises four stator flow channels and four rotor flow channels.

[0135] Embodiment 20: A rotary pulser configured to be positioned along a drill string through which drilling fluid flows, the rotary pulser comprising: a housing configured to be supported along the drill string; a stator supported by the housing, the stator having at least one stator flow channel extending from an upstream end to a downstream end of the stator; a rotor positioned adjacent to the stator, the rotor comprising at least one blocking element, the rotor rotatable to selectively block the at least one stator flow channel using the at least one blocking element; a motor coupled to the rotor, wherein the motor assembly is operable to rotate the rotor relative to the stator; and a controller configured to drive the motor and rotate the rotor relative to the stator, wherein the controller is configured to drive the rotation of the rotor in an oscillating manner such that: when the blocking element is moved from When the intermediate position is rotated to a first blocked angular position, a first selective blocking of the at least one stator flow channel by the at least one blocking element occurs, wherein the intermediate position is defined by minimal blocking of flow through the at least one stator flow channel by the blocking element; when the blocking element is rotated from the first blocked angular position to a second blocked angular position, a second selective blocking of the at least one stator flow channel by the at least one blocking element occurs, wherein when drilling fluid flows through the drill string to generate pressure pulses in the drilling fluid, the rotation of the blocking element selectively blocks the at least one stator flow channel, and wherein the oscillation mode is an oscillation of the at least one blocking element between the first blocked angular position and the second blocked angular position, so that the rotation direction of the rotor changes at the first blocked angular position and the second blocked angular position.

[0136] Embodiment 21: The rotary pulser according to any one of the preceding embodiments, wherein the maximum rotational speed of the rotor is reached at the intermediate position.

[0137] Embodiment 22: The rotary pulser according to any one of the preceding embodiments, wherein the minimum rotational speed of the rotor is achieved at the first blocking angular position and the second blocking angular position.

[0138] Embodiment 23: The rotary pulser according to any of the preceding embodiments, further comprising a biasing element configured to maintain the at least one blocking element approximately in the intermediate position such that the at least one stator flow channel is open for passage of the drilling fluid.

[0139] Embodiment 24: The rotary pulser according to any one of the preceding embodiments, wherein the motor is configured to overcome the biasing force of the biasing element to drive the at least one blocking element toward at least one of the first blocking angular position and the second blocking angular position.

[0140] Embodiment 25: The rotary pulser according to any one of the preceding embodiments, wherein the biasing element is a torsion bar.

[0141] Embodiment 26: The rotary pulser according to any one of the preceding embodiments, wherein the at least one blocking element comprises chamfered sidewalls.

[0142] Embodiment 27: The rotary pulser according to any one of the preceding embodiments, wherein the chamfered sidewall extends from the upstream face of the at least one blocking element to a chamfer depth.

[0143] Embodiment 28: The rotary pulser according to any one of the preceding embodiments, wherein the chamfer depth is between about 2 mm and about 10 mm.

[0144] Embodiment 29: The rotary pulser according to any one of the preceding embodiments, wherein the chamfered sidewall extends from the upstream face of the at least one blocking element at a chamfered angle.

[0145] Embodiment 30: The rotary pulser according to any one of the preceding embodiments, wherein the chamfer angle is between about 5° and about 45°.

[0146] Embodiment 31: The rotary pulser according to any one of the preceding embodiments, further comprising a rotor shaft operatively connecting the motor to the rotor.

[0147] Embodiment 32: The rotary pulser according to any one of the preceding embodiments, further comprising a bearing housing, wherein the rotor shaft extends through the bearing housing.

[0148] Embodiment 33: The rotary pulser according to any one of the preceding embodiments, further comprising one or more seals fixedly connected to the bearing housing and in sealing contact with the rotor shaft.

[0149] Embodiment 34: A rotary pulser according to any of the preceding embodiments, wherein the controller is configured to employ at least one of amplitude shift keying (ASK), frequency shift keying (FSK), pulse position modulation (PPM), quadrature phase shift keying (QPSK) and phase shift keying (PSK).

[0150] Embodiment 35: The rotary pulser according to any one of the preceding embodiments, wherein the pressure pulses have a sinusoidal pressure curve.

[0151] Embodiment 36: The rotary pulser according to any one of the preceding embodiments, wherein the controller is configured to adjust at least one of the first blocking angle of the first blocking angle position and the second blocking angle of the second blocking angle position to adjust the amplitude of the pressure pulse.

[0152] Embodiment 37: The rotary pulser according to any of the preceding embodiments, wherein the stator comprises a single stator flow channel and the rotor comprises a single blocking element.

[0153] Embodiment 38: The rotary pulser according to any one of the preceding embodiments, wherein the controller is configured to receive a downlink including operating instructions for driving rotation of the rotor.

[0154] Embodiment 39: The rotary pulser according to any one of the preceding embodiments, wherein the rotor is arranged downstream of the stator.

[0155] Embodiment 40: The rotary pulser according to any one of the preceding embodiments, wherein the motor is one of a reversible brushless DC motor, a servo motor, or a stepper motor.

[0156] Embodiment 41: The rotary pulser according to any of the preceding embodiments, further comprising at least one pressure sensor arranged to monitor the pressure of the pressure pulses.

[0157] Embodiment 42: The rotary pulser according to any one of the preceding embodiments, comprising four stator flow channels and four rotor flow channels.

[0158] Embodiment 43: The rotary pulser according to any one of the preceding embodiments, wherein a reversal oscillation point is located at each of the first blocking angular position and the second blocking angular position.

[0159] The systems and methods described herein provide various advantages. For example, compared to prior art systems and methods, the embodiments provided herein enable improved and more efficient data transmission via mud pulse telemetry. For example, a more defined and easily reconstructed signal can be generated. Closed-to-closed operation provides a clean sinusoidal signal, compared to previous configurations that generated higher crest factor signals. Furthermore, the chamfered sidewalls on the blocking element provide smoother operation, minimizing torque instabilities, particularly when the pulser assembly is in the closed-to-closed state.

[0160] To support the teachings herein, various analysis components may be used, including digital systems and / or analog systems. For example, a controller, computer processing system, and / or geosteering system as provided herein and / or used with the embodiments described herein may include a digital system and / or an analog system. These systems may have components such as processors, storage media, memory, inputs, outputs, communication links (e.g., wired, wireless, optical, or other), user interfaces, software programs, signal processors (e.g., digital or analog), and other such components (e.g., resistors, capacitors, inductors, etc.) for providing operation and analysis of the apparatus and methods disclosed herein in any of several ways well known in the art. It is contemplated that these teachings may, but need not, be implemented in conjunction with a set of computer-executable instructions stored on a non-transitory computer-readable medium, including memory (e.g., ROM, RAM), optical media (e.g., CD-ROM), or magnetic media (e.g., disk, hard drive), or any other type of media, which, when executed, cause a computer to implement the methods and / or processes described herein. In addition to the functions described in this disclosure, these instructions may also provide equipment operation, control, data collection, analysis and other functions that the system designer, owner, user or other such personnel consider relevant. Processed data (such as the result of the implemented method) may be transmitted to a signal receiving device via a processor output interface as a signal. The signal receiving device may be a display monitor or printer for presenting the result to the user. Alternatively or in addition thereto, the signal receiving device may be a memory or a storage medium. It should be understood that storing the result in a memory or a storage medium may convert the memory or the storage medium from a previous state (i.e., not including the result) to a new state (i.e., including the result). In addition, in some embodiments, if the result exceeds a threshold value, an alarm signal may be transmitted from the processor to the user interface.

[0161] In addition, various other components may be included and required to provide various aspects of the teachings herein. For example, sensors, transmitters, receivers, transceivers, antennas, controllers, optical units, electrical units, and / or electromechanical units may be included to support various aspects discussed herein or to support other functionality beyond the present disclosure.

[0162] The elements of the embodiments have been introduced by the articles "a" or "an". The articles are intended to indicate that there are one or more of these elements. The terms "including" and "having" are intended to be inclusive, such that there may be additional elements other than the listed elements. The conjunction "or" when used with a list of at least two terms is intended to mean any term or combination of terms. The term "configuration" refers to one or more structural limitations of a device that are required to perform the function or operation for which the device is configured. The terms "first" and "second" do not indicate a particular order, but are used to distinguish different elements.

[0163] Many variations may be made to the steps (or operations) described herein without departing from the scope of the present disclosure. For example, the steps may be performed in a different order, or steps may be added, deleted, or modified. All of these variations are considered part of the present disclosure.

[0164] It should be recognized that various components or techniques may provide certain necessary or advantageous functions or features. Therefore, these functions and features that may be required to support the appended claims and their variants are considered to be inherently included as part of the teachings herein and part of the present disclosure.

[0165] Although the embodiments described herein have been described with reference to various embodiments, it will be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications will be made to adapt specific instruments, situations, or materials to the teachings of the present disclosure without departing from the scope of the present disclosure. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed as the best mode contemplated for implementing the described features, but that the present disclosure will include all embodiments falling within the scope of the appended claims.

[0166] Accordingly, the disclosed embodiments are not to be seen as limited by the foregoing description, but are only limited by the scope of the appended claims.

Claims

1. A method for generating pressure pulses in a drilling fluid, the method comprising: Driving rotation of a rotor relative to a stator of a pulser assembly in an oscillatory manner, wherein the pulser assembly includes a tool housing disposed along a drill string, and the stator and the rotor are disposed within the tool housing, wherein the stator includes at least one stator flow channel to permit drilling fluid to flow therethrough, and the rotor includes at least one rotor flow channel to permit drilling fluid to flow therethrough and includes at least one blocking element configured to selectively block the flow of drilling fluid through the at least one stator flow channel, wherein the oscillatory manner comprises: rotating the at least one blocking element from an intermediate position to a first blocking angular position such that a first selective blocking of the at least one stator flow channel by the at least one blocking element occurs, wherein the intermediate position is defined by minimal blocking of drilling fluid flow through the at least one stator flow channel by the at least one blocking element; and rotating the at least one blocking element from the first blocking angular position to a second blocking angular position such that a second selective blocking of the at least one stator flow channel by the at least one blocking element occurs, wherein the rotation of the at least one blocking element occurs at a rotational speed and selectively blocks the at least one stator flow channel when drilling fluid flows through the drill string to generate pressure pulses in the drilling fluid, wherein the oscillation mode is an oscillation of the at least one blocking element between the first blocking angular position and the second blocking angular position, so that the rotation direction of the rotor changes at the first blocking angular position and the second blocking angular position, and The rotational speed of the at least one blocking element at the intermediate position is greater than the rotational speed of the at least one blocking element at the first blocking angular position or the second blocking angular position. 2 . The method of claim 1 , wherein the rotation of the at least one blocking element from the first blocking angular position to the second blocking angular position comprises passing through the intermediate position. The method according to claim 1 , wherein the maximum rotational speed of the rotor is reached at the intermediate position.

4. The method of claim 1, further comprising biasing the rotor to maintain the at least one blocking element in the intermediate position such that the at least one stator flow channel is open to passage of the drilling fluid. The method of claim 1 , wherein the at least one blocking element comprises a chamfered sidewall.

6. The method of claim 1, further comprising transmitting downhole information from the pulser assembly using at least one of amplitude shift keying, frequency shift keying, pulse position modulation, quadrature phase shift keying, and phase shift keying. The method of claim 1 , wherein the pressure pulse has a sinusoidal pressure profile. 8 . The method of claim 1 , further comprising adjusting at least one of a first blocking angle at the first blocking angular position and a second blocking angle at the second blocking angular position to adjust an amplitude of the pressure pulse.

9. The method of claim 1, wherein the pulser assembly comprises a single stator flow channel and a single blocking element.

10. The method of claim 1, further comprising receiving a downlink including operating instructions for driving rotation of the rotor.

11. The method of claim 1 , further comprising maximum obstruction of drilling fluid flow through the at least one stator flow channel, wherein the maximum obstruction is achieved when the at least one blocking element is in each of the first blocked angular position and the second blocked angular position.

12. The method of claim 11, wherein a maximum pressure increase is achieved at the second blocked angular position.

13. A rotary pulser configured to be positioned along a drill string through which drilling fluid flows, the rotary pulser comprising: a housing configured to be supported along the drill string; a stator supported by the housing, the stator having at least one stator flow passage extending from an upstream end to a downstream end of the stator; a rotor positioned adjacent to the stator, the rotor including at least one blocking element, the rotor rotatable to selectively block the at least one stator flow channel with the at least one blocking element; a motor coupled to the rotor, wherein the motor assembly is operable to rotate the rotor relative to the stator; and a controller configured to drive the motor and rotate the rotor relative to the stator, wherein the controller is configured to drive rotation of the rotor in an oscillatory manner such that: a first selective blocking of the at least one stator flow channel by the at least one blocking element occurs when the blocking element is rotated from an intermediate position to a first blocking angular position, wherein the intermediate position is defined by minimal blocking of drilling fluid flow through the at least one stator flow channel by the blocking element, a second selective blocking of the at least one stator flow channel by the at least one blocking element occurs when the blocking element rotates from the first blocking angular position to a second blocking angular position, wherein the rotation of the blocking element occurs at a rotational speed and selectively blocks the at least one stator flow channel when drilling fluid flows through the drill string to generate pressure pulses in the drilling fluid, wherein the oscillation mode is an oscillation of the at least one blocking element between the first blocking angular position and the second blocking angular position, so that the rotation direction of the rotor changes at the first blocking angular position and the second blocking angular position, and The rotational speed of the at least one blocking element at the intermediate position is greater than the rotational speed of the at least one blocking element at the first blocking angular position or the second blocking angular position.

14. The rotary pulser of claim 13, wherein the at least one blocking element comprises a chamfered side wall.

15. The rotary pulser of claim 13, further comprising a rotor shaft operatively connecting the motor to the rotor.

16. The rotary pulser according to claim 13, wherein the pressure pulses have a sinusoidal pressure curve. 17 . The rotary pulser of claim 13 , wherein the controller is configured to adjust at least one of a first blocking angle at the first blocking angular position and a second blocking angle at the second blocking angular position to adjust an amplitude of the pressure pulse.

18. The rotary pulser of claim 13, wherein the stator comprises a single stator flow channel, and the rotor comprises a single blocking element.

19. The rotary pulser of claim 13, further comprising at least one pressure sensor arranged to monitor the pressure of the pressure pulses.

20. The rotary pulser according to claim 13, comprising four stator flow channels and four rotor flow channels.

21. The rotary pulser of claim 13, further comprising maximum obstruction of drilling fluid flow through the at least one stator flow channel, wherein the maximum obstruction is achieved when the at least one blocking element is in each of the first blocked angular position and the second blocked angular position.

22. The rotary pulser of claim 21, wherein a maximum pressure increase is achieved at the second blocked angular position.

23. The rotary pulser according to claim 13, wherein the maximum rotation speed of the rotor is achieved at the intermediate position.

24. The rotary pulser of claim 13, further comprising a biasing element configured to maintain the at least one blocking element in the intermediate position such that the at least one stator flow channel is open to passage of the drilling fluid.

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