Drill bit support assembly incorporating dampener for high frequency torsional oscillations

Abstract

This invention describes a method and system for damping torsional oscillations in a downhole system. The system includes: a downhole tubing string; a drill bit support assembly configured to support and receive a fracturing device, wherein the fracturing device is disposed at an end of the downhole tubing string and mounted to the drill bit support assembly; and a damping system disposed at at least one of the following locations: on and / or in the drill bit support assembly, the damping system including at least one damper element arranged to contact a portion of the drill bit support assembly.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Patent Application 16 / 568789, filed September 12, 2019, the entire contents of which are incorporated herein by reference. Background Technology 1. Technical Field

[0004] The present invention relates generally to downhole operations and systems for damping vibrations in downhole systems during operation.

[0005] 2. Description of related technologies

[0006] Drilling boreholes deep underground is used for many applications, such as carbon dioxide sequestration, geothermal production, and oil and gas exploration and production. In all these applications, boreholes are drilled so that they penetrate or allow access to materials (e.g., gases or fluids) contained in strata located below the surface (e.g., sequestration chambers). Different types of tools and instruments can be set in the boreholes to perform a variety of tasks and measurements.

[0007] During operation, downhole components can be subjected to vibration, which can affect operational efficiency. For example, severe vibration in the drill string and bottom hole assembly can be caused by cutting forces at the drill bit or mass imbalances in downhole tools (such as mud motors). The effects of such vibration can include, but are not limited to, reduced drilling rates, reduced measurement quality, and excessive fatigue and wear of downhole components, tools, and / or equipment. Summary of the Invention

[0008] This document discloses systems and methods for damping oscillations (such as torsional oscillations) in downhole systems. The system includes a downhole system arranged to rotate within a borehole and a damping system configured on the downhole system. The damping system includes one or more dampers mounted at or within the drill bit support assembly of the downhole system. These dampers are arranged to reduce or eliminate one or more specific vibration modes, and thus enable improved downhole operation and / or efficiency.

[0009] Furthermore, the present invention describes a method and system for damping torsional oscillations in a downhole system. The system includes: a downhole tubing string; a drill bit support assembly configured to support and receive a fracturing device, wherein the fracturing device is disposed at an end of the downhole tubing string and mounted to the drill bit support assembly; and a damping system disposed at at least one of the following locations: on and / or in the drill bit support assembly, the damping system including at least one damper element arranged to contact a portion of the drill bit support assembly.

[0010] The method includes installing a damping system at at least one of the following: on and / or in a drill bit support assembly on a downhole string of a downhole system, the drill bit support assembly having a fracturing device attached thereto. The damping system includes at least one damper element arranged to contact a portion of the drill bit support assembly, wherein at least a portion of the damper element moves relative to the drill bit support assembly at a velocity that is the sum of a periodic velocity fluctuation with amplitude and an average velocity. Attached Figure Description

[0011] The subject matter considered to be the invention is specifically pointed out and explicitly claimed in the claims at the end 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, wherein similar elements have similar reference numerals, in which:

[0012] Figure 1 Examples of systems for performing downhole operations that can adopt embodiments of this disclosure;

[0013] Figure 2 It is an illustrative graph of the typical curve of friction or torque between two interacting subjects versus relative velocity or relative rotational speed;

[0014] Figure 3 It is a graph showing the hysteresis curve of friction force versus displacement for a positive relative average velocity with additional small velocity fluctuations.

[0015] Figure 4 It is a graph of friction, relative velocity, and their product against time for a positive relative average velocity with additional small velocity fluctuations.

[0016] Figure 5 It is a graph showing the hysteresis curve of friction force versus displacement for a zero relative average velocity with additional small velocity fluctuations.

[0017] Figure 6 It is a graph of friction, relative velocity, and the product of the two for zero relative average velocity with additional small velocity fluctuations;

[0018] Figure 7 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0019] Figure 8A It is a graph of tangential acceleration measured at the drill bit;

[0020] Figure 8B It corresponds to Figure 8A The graph shows the rotational speed;

[0021] Figure 9AThis is a schematic diagram of the downhole system, showing how the mode shape of the downhole system changes with distance from the drill bit;

[0022] Figure 9B It shows that it can be used Figure 9A Exemplary corresponding mode shapes of torsional vibrations excited during the operation of downhole systems;

[0023] Figure 10 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0024] Figure 11 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0025] Figure 12 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0026] Figure 13 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0027] Figure 14 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0028] Figure 15 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0029] Figure 16 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0030] Figure 17 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0031] Figure 18 This is a schematic diagram of a damping system according to one embodiment of the present disclosure;

[0032] Figure 19 This is a schematic diagram of a damping system according to one embodiment of the present disclosure; and

[0033] Figure 20 This is a schematic diagram illustrating the effect of modal damping ratio on local vibration amplitude;

[0034] Figure 21 This is a schematic diagram of a downhole tool with a damping system;

[0035] Figure 22 yes Figure 21 A cross-sectional view of the downhole tools;

[0036] Figure 23 This is a schematic diagram of a drill bit support assembly incorporating a damper element according to one embodiment of the present disclosure;

[0037] Figure 24 This is a schematic diagram of a tangential damper element according to one embodiment of the present disclosure;

[0038] Figure 25 This is a schematic diagram of a tangential damper element according to one embodiment of the present disclosure;

[0039] Figure 26 It is an illustrative graph of typical forces or torques between two interacting bodies associated with a hydraulic damper element versus relative velocity or relative rotational speed; and

[0040] Figure 27 This is a schematic diagram of a drill bit support assembly incorporating a damper element according to one embodiment of the present disclosure. Detailed Implementation

[0041] Figure 1 A schematic diagram of a system for performing downhole operations is shown. As shown, the system is a drilling system 10, which includes a drill string 20 having a drilling assembly 90 (also referred to as a bottom hole assembly (BHA)) delivered in a borehole 26 penetrating the formation 60. The drilling system 10 includes a conventional derrick 11 erected on a base plate 12 supporting a rotary table 14, which is rotated at a desired rotational speed by a prime mover (such as an electric motor (not shown)). The drill string 20 includes a drilling tubing 22, such as drill pipe, extending downwards from the rotary table 14 into the borehole 26. A fracturing device 50 (such as a drill bit attached to the end of the BHA 90) fractures the geological formation as it rotates to drill the borehole 26. The drill string 20 is connected to surface equipment, such as a system for lifting, rotating, and / or pushing (including but not limited to) the winch 30 via pulley 23 through the square drill pipe joint 21, swivel 28, and line 29. In some embodiments, the surface equipment may include a top drive (not shown). During drilling operations, the winch 30 is operated to control the pressure on the drill bit, which affects the drilling rate. The operation of the winch 30 is well known in the art and will not be described in detail herein.

[0042] During drilling operations, suitable drilling fluid 32 (also referred to as “mud”) from the source or mud pit 31 is circulated under pressure through the drill string 20 by a mud pump 34. The drilling fluid 31 enters the drill string 20 via a wave eliminator 36, a fluid line 38, and a kerb joint 21. The drilling fluid 31 is discharged at the bottom of the borehole 51 through an opening in the fracturing device 50. The drilling fluid 31 circulates upwards along the wellbore through the annular gap 27 between the drill string 20 and the borehole 26, and returns to the mud pit 32 via a return line 35. A sensor S1 in the fluid line 38 provides information about the fluid velocity. Surface torque sensors S2 and S3, associated with the drill string 20, provide information about the torque and rotational speed of the drill string, respectively. Additionally, one or more sensors (not shown) associated with line 29 are used to provide information about the hook load on the drill string 20 and other desired parameters related to drilling of the borehole 26. The system may also include one or more downhole sensors 70 positioned on the drill string 20 and / or BHA 90.

[0043] In some applications, the fracturing device 50 is rotated solely by rotating the drill string 22. However, in other applications, a drill motor 55 (e.g., a mud motor) housed within the drilling assembly 90 is used to rotate the fracturing device 50 and / or to superimpose or supplement the rotation of the drill string 20. In either case, for a given formation and a given drilling assembly, the rate of penetration (ROP) of the fracturing device 50 into the formation 60 depends largely on the pressure on the drill bit and the drill bit rotation speed. Figure 1 In one aspect of the implementation, a drilling motor 55 is coupled to a fracturing device 50 via a drive shaft (not shown) disposed in a bearing assembly 57. The drilling motor 55 rotates the fracturing device 50 as drilling fluid 31 passes under pressure through it. The bearing assembly 57 supports the radial and axial forces on the fracturing device 50, the downward thrust of the drilling motor, and the reactive upward load from the applied drilling pressure. A stabilizer 58, coupled to the bearing assembly 57 and / or other suitable locations, acts as a centralizer for the drilling assembly 90 or a portion thereof.

[0044] The surface control unit 40 receives signals from downhole sensors 70 and equipment via transducers 43, such as pressure transducers, placed in fluid lines 38, and from sensors S1, S2, S3, hook load sensors, RPM sensors, torque sensors, and any other sensors used in the system, and processes such signals according to programmed instructions provided to the surface control unit 40. The surface control unit 40 displays desired drilling parameters and other information used by operators at the drilling rig site to control drilling operations on a display / monitor 42. The surface control unit 40 includes a computer; a memory for storing processor-accessible data, computer programs, models, and algorithms; a recorder, such as a magnetic tape unit, a memory unit, etc., for recording data; and other peripheral devices. The surface control unit 40 may also include a simulation model used by the computer to process data according to programmed instructions. The control unit responds to user commands entered via a suitable device (such as a keyboard). The surface control unit 40 is adapted to activate an alarm 44 in the event of certain unsafe or undesirable operating conditions.

[0045] Drilling assembly 90 also includes other sensors and devices or tools for providing various measurements related to the formation surrounding the borehole and for drilling the borehole 26 along a desired path. Such devices may include equipment for measuring formation resistivity near and / or in front of the drill bit, gamma-ray equipment for measuring formation gamma-ray intensity, and equipment for determining the drill string inclination, azimuth, and position. A formation resistivity tool 64, fabricated according to the embodiments described herein, can be coupled at any suitable location (including above the lower initiator assembly or steering unit 62) to estimate or determine the formation resistivity near or in front of the fracturing device 50 or at other suitable locations. Inclinometer 74 and gamma-ray equipment 76 may be suitably positioned to determine the inclination and formation gamma-ray intensity of the BHA, respectively. Any suitable inclinometer and gamma-ray equipment may be used. Additionally, an azimuth device (not shown) such as a magnetometer or gyroscope may be used to determine the drill string azimuth. Such devices are known in the art and therefore will not be described in detail herein. In the exemplary configuration described above, the drilling motor 55 transmits power to the fracturing device 50 via a shaft that also allows drilling fluid to be transferred from the drilling motor 55 to the fracturing device 50. In an alternative embodiment of the drill string 20, the drilling motor 55 may be coupled below the resistivity measuring device 64 or at any other suitable location.

[0046] Still referencing Figure 1Other logging-while-drilling (LWD) devices (generally designated as 77 here), such as devices for measuring formation porosity, permeability, density, rock properties, fluid properties, etc., may be placed in appropriate locations within the drilling assembly 90 to provide information for assessing the subsurface formation along the borehole 26. Such devices may include, but are not limited to, temperature measuring tools, pressure measuring tools, borehole diameter measuring tools (e.g., calipers), acoustic tools, nuclear tools, nuclear magnetic resonance tools, and formation testing and sampling tools.

[0047] The aforementioned equipment transmits data to a downhole telemetry system 72, which in turn transmits the received data upwards along the wellbore to a surface control unit 40. The downhole telemetry system 72 also receives signals and data from the surface control unit 40 and transmits such received signals and data to appropriate downhole equipment. In one aspect, a mud pulse telemetry system can be used to transmit data between the downhole sensor 70 and equipment and surface equipment during drilling operations. A transducer 43, placed in a fluid line 38 (e.g., a mud supply line), detects mud pulses in response to data transmitted by the downhole telemetry system 72. The transducer 43 generates an electrical signal in response to changes in mud pressure and transmits such a signal via a conductor 45 to the surface control unit 40. In other respects, any other suitable telemetry system may be used for two-way data communication (e.g., downlink and uplink) between the ground and BHA 90. These telemetry systems include, but are not limited to, acoustic telemetry systems, electromagnetic telemetry systems, optical telemetry systems, and wired telemetry systems, which may utilize wireless couplers or repeaters within the drill string or borehole. A wired telemetry system can be constructed by connecting drill pipe segments, each segment including a data communication link (such as an electrical wire) extending along the pipe. Data connections between segments can be made by any suitable method, including but not limited to hard electrical or optical connections, inductive, capacitive, resonant coupling (such as electromagnetic resonant coupling), or directional coupling methods. When coiled tubing is used as drill pipe 22, the data communication link may extend along the side of the coiled tubing.

[0048] The drilling systems described so far relate to those that utilize drill tubing to deliver drilling assemblies 90 into the borehole 26, where pressure on the drill bit is typically controlled from the surface by controlling the operation of a winch. However, a large number of current drilling systems, particularly those used for drilling highly skewed and horizontal boreholes, utilize coiled tubing to deliver drilling assemblies downhole. In such applications, thrusters are sometimes deployed in the drill string to provide the desired force at the drill bit. Additionally, when coiled tubing is used, the tubing is not rotated via a rotary table, but rather injected into the borehole via a suitable injector, while a downhole motor (such as drilling motor 55) rotates the fracturing equipment 50. For offshore drilling, offshore drilling rigs or vessels are used to support the drilling equipment, including the drill string.

[0049] Still referencing Figure 1 A resistivity tool 64 may be provided, which includes, for example, multiple antennas, including, for example, transmitters 66a or 66b and / or receivers 68a or 68b. Resistivity may be a formation property of interest when making drilling decisions. Those skilled in the art will understand that other formation property tools may be used in conjunction with or in place of the resistivity tool 64.

[0050] Tail-end drilling can be a configuration or operation used to provide fracturing equipment and is becoming increasingly attractive in the oil and gas industry due to several advantages compared to conventional drilling. An example of such a configuration is shown and described in co-owned U.S. Patent No. 9,004,195, entitled “Apparatus and Method for Drilling a Borehole, Setting a Liner and Cementing the Borehole During a Single Trip,” the entire contents of which are incorporated herein by reference. Importantly, despite the relatively low drilling rate, the time required to align the tail-end with the target is reduced because it is run into the borehole simultaneously. This can be beneficial in expanding formations where borehole contraction can hinder tail-end installation. Furthermore, using tail-end drilling in depleted and unstable oil formations minimizes the risk of casing or drill string jamming due to borehole collapse.

[0051] although Figure 1 This disclosure pertains to drilling operations, but those skilled in the art will understand that, despite the different components, similar configurations can be used to perform various downhole operations. For example, as known in the art, cabled, wireline, tailpipe drilling, reaming, coiled tubing, and / or other configurations can be used. Furthermore, production configurations can be employed for extracting materials from and / or injecting materials into the formation. Therefore, this disclosure is not limited to drilling operations but can be applied to any suitable or desired one or more downhole operations.

[0052] Severe vibrations in the drill string and bottomhole assembly during drilling operations can be caused by cutting forces at the drill bit or mass imbalances in downhole tools (such as drilling motors). Such vibrations can lead to reduced drilling rates, decreased quality of measurements performed by the tools in the bottomhole assembly, and wear, fatigue, and / or failure of downhole components. As those skilled in the art will understand, different types of vibration exist, such as lateral vibration, axial vibration, and torsional vibration. For example, viscous / slippage and high-frequency torsional oscillations (“HFTO”) throughout the drilling system are types of torsional vibration. The terms “vibration,” “oscillation,” and “fluctuation” are used in the same broad sense as repetitive and / or periodic movements or periodic deviations from average values ​​(such as average position, average velocity, average acceleration, average force, and / or average torque). Specifically, these terms are not intended to be limited to harmonic deviations but can include all kinds of deviations, such as, but not limited to, periodic deviations, harmonic deviations, and statistical deviations. Torsional vibrations can be induced by self-excitation mechanisms arising from the interaction of the drill bit or any other cutting structure (such as a reamer bit) with the formation. The main difference between viscous / slip and HFTO lies in the frequency and typical mode shapes: for example, HFTO typically has frequencies above 50 Hz, compared to viscous / slip torsional vibrations which are typically below 1 Hz. Furthermore, the excited mode shapes of viscous / slip are usually the first mode shape of the entire drilling system, while the mode shapes of HFTO can be higher-order and are typically confined to a smaller part of the drilling system with relatively high amplitudes at the excitation point, which can be the drill bit or any other cutting structure (such as a reamer bit) or any contact between the drilling system and the formation (e.g., achieved by a stabilizer).

[0053] Due to the high frequency of the vibration, HFTO corresponds to high acceleration and torque values ​​along the BHA. Those skilled in the art will understand that for torsional motion, one of acceleration, force, and torque is always accompanied by the other two. In this sense, acceleration, force, and torque are equivalent in that none of them would occur without the other two. The load of high-frequency vibration can negatively impact the efficiency, reliability, and / or durability of the electronic and mechanical components of the BHA. The embodiments provided herein relate to providing torsional vibration damping on downhole systems to mitigate HFTO. In some embodiments of this disclosure, torsional vibration damping can be activated if a threshold value for a measured characteristic (such as torsional vibration amplitude or frequency) is achieved within the system.

[0054] According to the non-limiting embodiments provided herein, the torsional vibration damping system may be based on a friction damper. For example, according to some embodiments, friction between two components (such as two interacting bodies) in the BHA or drill string can dissipate energy and reduce the level of torsional oscillations, thereby mitigating potential damage caused by high-frequency vibrations. Preferably, the energy dissipation of the friction damper is at least equal to the HFTO energy input caused by the drill bit-rock interaction.

[0055] The friction damper described herein can cause significant energy dissipation and thus reduce torsional vibration. When two components or interacting bodies are in contact with each other and move relative to each other, friction acts in the opposite direction to the relative velocities of the contact surfaces of these components or interacting bodies. Friction causes energy dissipation.

[0056] Although specific descriptions have been given regarding friction dampers, the dampers, damper elements, and damper systems disclosed herein are not limited to friction. That is, as described below, other principles of damping can be achieved using dampers with different configurations. For example, damping can be generated by viscous damping, frictional damping, hydraulic damping, magnetic damping (e.g., eddy current damping), piezoelectric (shunt) damping, etc. As used herein, a damper element can be part of a damping system configured to dissipate energy caused by relative movement between at least a portion of the damper element and the downhole tubing. That is, relative movement of the damper element or a portion thereof allows energy (e.g., HFTO) to be dissipated, and thus reduces vibrations within or along the downhole tubing.

[0057] Figure 2 Figure 200 is an illustrative curve of a typical curve of friction or torque between two interacting bodies against relative velocity v (e.g., relative rotational speed). The two interacting bodies have contact surfaces and a force component F perpendicular to the contact surfaces that engage the two interacting bodies. N Figure 200 illustrates the correlation between frictional force or torque between two interacting subjects and speed-weakening behaviors such as cutting behavior in frictional contact or characteristics. At higher relative velocities (v > 0) between the two interacting subjects, the frictional force or torque exhibits different values ​​as shown by point 202. Decreasing the relative velocity will result in an increase in frictional force or torque (also known as speed-weakening characteristics). When the relative velocity is zero, the frictional force or torque reaches its maximum value. Maximum frictional force is also known as static friction, adhesive friction, or viscous friction.

[0058] Typically, frictional force F R Depends on the normal force, as in equation F R =μ·F NAs described in the text, the coefficient of friction is μ. Generally speaking, the coefficient of friction μ is a function of velocity. In this paper, the normal force can also correspond to the undulation of excited vibrations in the normal direction. When the relative velocity between two interacting bodies is zero (v = 0), the static friction force F S With normal force component F N The relevant equation is F. S =μ0·F N The static friction coefficient is μ0. When the relative velocity between two interacting bodies is not zero (v≠0), the friction coefficient is called the dynamic friction coefficient μ. If the relative velocity further decreases to a negative value (i.e., if the direction of relative motion of the two interacting bodies switches to the opposite direction), the frictional force or torque switches to the opposite direction and has a high absolute value at point 204 in graph 200, corresponding to the step from a positive maximum to a negative minimum. That is, the relationship between frictional force and velocity shows the sign change at the point where the velocity changes sign and is discontinuous at point 204 in graph 200. Velocity weakening is a well-known effect between frictionally connected interacting bodies. The velocity weakening characteristic of contact force or torque is considered a potential root cause of viscosity / slippage. Velocity weakening can also be achieved by utilizing a dispersed fluid with higher viscosity at lower relative velocities and lower viscosity at higher relative velocities. The same effect can be achieved if the dispersed fluid is forced through a relatively small channel, since the flow resistance is relatively high or low at low or high relative velocities, respectively.

[0059] refer to Figures 8A to 8B , Figure 8A The measured torsional acceleration of the downhole system versus time is shown. Figure 8A During the 5-second measurement time shown, Figure 8A An oscillating torsional acceleration with an average acceleration of approximately 0g is shown, which is superimposed with an oscillating torsional acceleration having a relatively low amplitude between approximately 0s and 3s and a relatively high amplitude of up to 100g between approximately 3s and 5s. Figure 8B It shows the relationship with Figure 8A The corresponding rotational speed within the same time period. According to Figure 8A , Figure 8B The average velocity v0 is shown (in) Figure 8B (Indicated by line v0), this average speed is relatively constant at approximately 190 revolutions per minute. This average speed is determined by... Figure 8AThe relatively low and high acceleration amplitudes in the oscillating rotational velocity are superimposed, with a relatively low amplitude between approximately 0 s and 3 s and a relatively high amplitude between approximately 3 s and 5 s. It is noteworthy that even within the time period of approximately 3 s and 5 s, when the amplitude of the rotational velocity oscillation is relatively high, the oscillating rotational velocity does not cause a negative value in the rotational velocity.

[0060] Refer again Figure 2 Point 202 shows the average velocity of the two interacting entities, which corresponds to Figure 8B The average velocity v0 in the middle. Figure 2 In the schematic diagram, Figure 8B The data corresponds to points with velocities that oscillate at a relatively high frequency around the average velocity v0 due to HTFO, which changes relatively slowly over time compared to HFTO. Therefore, it is shown that... Figure 8B The data points are at Figure 2 The curve moves back and forth on the positive branch, rarely or never reaching negative velocity values. Therefore, the corresponding frictional force or torque oscillates around the positive average frictional force or average frictional torque and is generally positive or only rarely negative. As discussed further below, point 202 shows the location where the positive average relative velocity corresponds to the static torque, and point 204 shows the advantageous point for frictional damping. It should be noted that the frictional force or torque between the drilling system and the borehole wall does not produce additional damping for the high-frequency oscillations in the system. This is because the average velocity of the relative velocity between the contact surfaces of the interacting subjects (e.g., the stabilizer and the borehole wall) is not so close to zero that the HFTO causes a sign change in the relative velocity of the two interacting subjects. Instead, the relative velocity between the two interacting subjects has a high average value at a certain distance from zero, which is large enough that the HFTO does not cause a sign change in the relative velocity of the two interacting subjects (e.g., by...). Figure 2 Point 202 is shown in the diagram.

[0061] As those skilled in the art will understand, Figure 2 The weakening characteristic of the contact force or torque relative to the relative velocity, as shown, results in energy being applied to the system to cause the relative movement of the interacting subjects to oscillate at an average velocity v0, which is high compared to the velocity of the oscillating movement. In this context, other examples of self-excited mechanisms, such as coupling between axial and torsional degrees of freedom, can induce similar characteristics.

[0062] The corresponding lag is Figure 3 Depicted in Figure 4 The graph shows the time curves of friction force and velocity. Figure 3 The frictional force F is shown. r(Sometimes referred to as cutting force in this context) the hysteresis relationship between displacement and position, which moves at a positive average relative velocity with additional small velocity fluctuations (causing additional small displacements dx). Therefore, Figure 4 This shows the frictional force (F) for a positive average relative velocity with additional small velocity fluctuations (causing additional small displacements dx). r ), relative velocity (dx / dτ) and their product (by Figure 4 (as indicated by label 400 in the text). Those skilled in the art will understand that the area between friction and velocity over time is equal to the dissipated energy (i.e., the area between line 400 and the zero axis), which is determined by... Figure 3 and Figure 4 The case shown is negative. That is, in the case of... Figure 3 and Figure 4 In the case shown, energy is transferred from friction to oscillation via frictional contact.

[0063] Refer again Figure 2 Point 204 represents the favorable average velocity for frictional damping of small velocity fluctuations or oscillations other than the average velocity. For small fluctuations in relative movement between two interacting bodies, Figure 2 The discontinuity at point 204 and the sign change of the relative velocities of the interacting entities also cause a sudden sign change in the frictional force or torque. This sign change causes hysteresis, resulting in a large amount of dissipated energy. For example, comparing... Figure 5 and Figure 6 , Figure 5 and Figure 6 respectively with Figure 3 and Figure 4 It has a similar graph, but shows the case of zero average relative velocity with additional small velocity fluctuations or vibrations. Figure 6 The line below 600 corresponds to the product F. r The area of ​​dx / dτ is equal to the energy dissipated over a time interval, and is positive in this case. That is, in the case of... Figure 5 and Figure 6 In the case shown, energy is transferred from high-frequency oscillations to friction via frictional contact. (This is in contrast to the previous example.) Figure 3 and Figure 4 Compared to the cases shown, this effect is considerably higher and has the expected positive or negative sign. According to... Figure 2 , Figure 5 and Figure 6 The comparison also clearly shows that the dissipated energy depends significantly on v = 0 (i.e., Figure 2 The difference between the maximum and minimum frictional forces at position 204. When v = 0, the larger the difference between the maximum and minimum frictional forces, the higher the energy dissipation. Although Figures 3 to 4By using speed weakening properties (such as Figure 2 The frictional force or torque is generated by the characteristics shown herein, but embodiments of this disclosure are not limited to this type of characteristic. The apparatus and methods disclosed herein will be effective for any type of characteristic, provided that the frictional force or torque undergoes a step with a sign change when the relative velocity between the two interacting subjects changes its sign.

[0064] Friction dampers according to some embodiments of this disclosure will now be described. Friction dampers are installed in drilling systems (such as...) Figure 1 The friction damper is on or in the drilling system 10 shown, and / or is part of the drilling system 10, such as part of a bottom hole assembly 90. The friction damper is part of a friction damping system having two interacting bodies, such as a first element and a second element having a frictional contact surface with the first element. The friction damping system of this disclosure is arranged such that the average velocity of the first element is related to the rotational velocity of the drilling system on which the first element is mounted. For example, the first element may have an average velocity or rotational velocity similar to or the same as that of the drilling system, such that small undulating oscillations cause... Figure 2 The sign change or zero crossing of the relative velocity between the first and second elements at point 204. It should be noted that the friction or torque between the drilling system and the borehole wall does not produce additional damping for high-frequency oscillations in the system. This is because the relative velocity between the contact surfaces (e.g., the stabilizer and the borehole) does not have a zero average value (e.g., ...). Figure 2 Point 202 in the document). According to the embodiment described herein, the static friction between the first and second elements is set sufficiently high such that the first element can accelerate the second element (during rotation) to an average speed v0 with the same value as the drilling system. Therefore, the additional high-frequency oscillation is based on being equal to or close to... Figure 2 Point 204 in Figure 2 The oscillations around the location in the middle introduce slippage between the first element (e.g., a damping device) and the second element (e.g., a drilling system) at positive or negative velocities. Inertial force F I Slippage occurs when the static friction force exceeds the coefficient of static friction between the two interacting bodies, which is expressed as the coefficient of static friction between the two bodies multiplied by the normal force: F I >μ0·F N According to the implementation scheme of this disclosure, the normal force F N (For example, caused by the contact and surface pressure of the contact surfaces between two interacting subjects) and the static friction coefficient μ0 are adjusted to achieve optimal energy dissipation or optimal amplitude. Furthermore, the moment of inertia (torsion), the contact and surface pressure of the contact surfaces, and the arrangement of the damper or contact surface relative to its distance from the drill bit can be optimized.

[0065] For example, turning Figure 7A schematic diagram of a damping system 700 according to one embodiment of the present disclosure is shown. The damping system 700 is part of a downhole system 702 (such as a bottom hole assembly and / or drilling assembly). The downhole system 702 includes a drill string 704 that rotates to enable drilling operations of the downhole system 702 to form a borehole 706 within a formation 708. As discussed above, the borehole 706 is typically filled with drilling fluid, such as drilling mud. The damping system 700 includes a first element 710 that is operatively coupled (e.g., fixedly coupled) or integral with the downhole system 702 to ensure that the first element 710 rotates at an average speed correlated with (e.g., similar to or the same as) the average speed of the downhole system 702. The first element 710 is in frictional contact with a second element 712. The second element 712 is at least partially movably mounted on the downhole system 702, wherein a contact surface 714 is located between the first element 710 and the second element 712.

[0066] Regarding friction, the difference between the minimum and maximum friction is positively correlated with the normal force and the static friction coefficient. Energy dissipation increases with friction and harmonic displacement, but only during the sliding phase. In the viscous phase, the relative displacement between the friction interfaces and the dissipated energy are zero. The upper amplitude limit of the viscous phase increases linearly with the normal force and friction coefficient at the contact interface. This is because one of the contacting elements... Under accelerated conditions, the reactive force at the contact interface can be caused by the inertia J of the contacting subject. The torque M must be higher than the limit between viscosity and slip. H =F NμHr As used in this article, F N It is a normal force, and μ H is the effective coefficient of friction, and r is the effective or average radius of the frictional contact area. For complex frictional contact parts with interacting subjects, both adhesion and sliding can occur simultaneously. In this paper, the contact pressure can be optimized to achieve optimal damping and amplitude.

[0067] If the contact force is caused by displacement and spring elements, a similar mechanism applies. Acceleration of the contact area. This can be attributed to the excitation of a mode and depends on the corresponding mode shape, as described below relative to... Figure 9B Further discussion. Regarding the added inertial mass J, as long as the contact interface is viscous, the acceleration... This is equal to the acceleration of the excited mode and the corresponding mode shape at the additional location.

[0068] The normal force and frictional force must be adjusted to ensure that the sliding phase is within a suitable or permissible amplitude range. The permissible amplitude range can be defined by the amplitude between zero and the load limit, which is given, for example, by the design specifications of the tool and component. The limit can also be given as a percentage of the expected amplitude without a damper. The dissipated energy, comparable to the energy input (e.g., by forced excitation or self-excitation), is a measure of the damper's efficiency. Another measure is the equivalent damping provided to the system, which is proportional to the ratio of the energy dissipated during one cycle of harmonic vibration in the system to the potential energy during one cycle of vibration. This measure is particularly effective for self-excited systems. In the case of self-excited systems, the excitation can be estimated by a negative damping coefficient, and both equivalent damping and negative damping can be directly compared. The damping force provided by the damper is nonlinear and strongly dependent on the amplitude.

[0069] like Figure 20 As shown, damping occurs during the viscous phase ( Figure 20 The left end of the curve (where the relative movement between the interacting entities is zero) is zero. If, as described above, the limit between the viscous and sliding stages is exceeded by the force transmitted through the contact interface, relative sliding motion causing energy dissipation occurs. Subsequently, the damping ratio provided by frictional damping increases to a maximum and then decreases to a minimum. The amplitude that will occur depends on the excitation, which can be described by the negative damping term. In this paper, as... Figure 20 The maximum value of the damping provided must be higher than the negative damping from the self-excited mechanism. The amplitude occurring in the so-called limiting cycle can be determined by the intersection of the negative damping ratio and the equivalent damping ratio provided by the friction damper.

[0070] This curve depends on various parameters. High normal force, but a slip phase occurring at the minimum amplitude of the bottom hole assembly, is advantageous. In terms of inertial mass, this can be achieved with high mass or by placing the contact interface at a point of high acceleration relative to the excited mode shape. In terms of the contact interface, high relative displacement is advantageous compared to the amplitude of the mode shape at the contact point, for example, along the axial axis of the BHA. Therefore, the optimal arrangement of the damping devices based on high amplitude or relative amplitude is important. This can be achieved using simulation results, as discussed below. Normal force and friction coefficient can be used to shift this curve to lower or higher amplitudes, but have little effect on the maximum damping value. If more than one friction damper is implemented, this will cause… Figure 20The superposition of similar curves is shown. Adjusting the normal force and coefficient of friction to achieve the same maximum amplitude benefits the overall damping achieved. Furthermore, a slight shift in the damping curve will result in a wider curve relative to the amplitude, which is beneficial for considering the effect of shifting the amplitude to the right of the maximum value. In this case, for a self-excited system, the amplitude will increase to an extremely high value, as indicated by negative damping. In this case, the amplitude needs to be shifted again to the left of the maximum value, for example, by moving away from the bottom or reducing the rotational speed of the system to a lower level. The amplitude in this context is determined by factors such as relative to the maximum value. Figure 8B The average rotational speed indicated and discussed scales approximately linearly.

[0071] Refer again Figure 7 The tubing string 704 and therefore the downhole system 702 rotate at a speed of The rotation is measured in revolutions per minute (RPM). The second element 712 is mounted on the first element 710. The normal force F between the first element 710 and the second element 712 can be selected or adjusted by adjusting the application and use of element 716. N The adjusting element 716 can be adjusted, for example via a thread, actuator, piezoelectric actuator, hydraulic actuator, and / or spring element, to apply a force having a component in a direction perpendicular to the contact surface 714 between the first element 710 and the second element 712. For example, as Figure 7 As shown, the adjusting element 716 can apply a force in the axial direction of the downhole system 702. Since the axis of the downhole system 702 forms a non-zero angle with the contact surface 714 of the first element 710 and the second element 712, this force is converted into a force component F perpendicular to the contact surface 714 of the first element 710 and the second element 712. N In some configurations, the angle between system 712 and the inertial mass element is selected or defined to allow sliding motion and avoid self-locking.

[0072] The second element 712 has a moment of inertia J. When an HFTO occurs during the operation of the downhole system 702, both the downhole system 702 and the second element 712 are accelerated according to the mode shape (e.g., the amplitude distribution defined along the dimensions of the drilling system, drill string, and / or BHA) and the amplitude of the mode (e.g., scaling the amplitude of the mode shape). Figure 8A and Figure 8B An exemplary result of this operation is shown in the figure. Figure 8A It is a graph of tangential acceleration measured at the drill bit, and Figure 8B That is the corresponding rotational speed.

[0073] Due to the tangential acceleration and inertia of the second element 712, a relative inertial force occurs between the second element 712 and the first element 710. If these inertial forces exceed the threshold between viscosity and slippage, i.e., if these inertial forces exceed the static friction between the first element 710 and the second element 710, relative motion will occur between elements 710 and 712, causing energy dissipation. In this arrangement, acceleration, the coefficient of static friction and / or the coefficient of dynamic friction, and the normal force determine the amount of energy dissipated. For example, the moment of inertia J of the second element 712 determines the relative force that must be transmitted between the first element 710 and the second element 712. High acceleration and moment of inertia increase the tendency to slip at the contact surface 714, thus causing higher energy dissipation and equivalent damping ratio provided by the damper.

[0074] Energy dissipation due to frictional movement between the first element 710 and the second element 712 will generate heat and wear on the first element 710 and / or the second element 712. To keep wear below an acceptable level, wear-resistant materials may be used for the first element 710 and / or the second element 712. For example, diamond or polycrystalline diamond composite sheets may be used for at least a portion of the first element 710 and / or the second element 712. Alternatively or additionally, coatings may help reduce wear caused by friction between the first element 710 and the second element 712. Heat can cause high temperatures and can affect the reliability or durability of the first element 710, the second element 712, and / or other components of the downhole system 702. The first element 710 and / or the second element 712 may be made of materials with high thermal conductivity or high heat capacity, and / or may be in contact with materials with high thermal conductivity or high heat capacity.

[0075] Such materials with high thermal conductivity include, but are not limited to, metals or metal-containing compounds such as copper, silver, gold, aluminum, molybdenum, tungsten, or hot greases containing fats, greases, oils, epoxy resins, silicones, polyurethanes, and acrylates, and optionally fillers such as diamond, metals or metal-containing chemical compounds (e.g., silver, aluminum in aluminum nitride, boron in boron nitride, zinc in zinc oxide) or silicon or silicon-containing chemical compounds (e.g., silicon carbide). In addition or alternatively, one or both of the first element 710 and the second element 712 may be in contact with a fluid (such as drilling fluid) configured to remove heat from the first element 710 and / or the second element 712 to cool the respective elements 710, 712. Furthermore, amplitude limiting elements (not shown), such as keys, grooves, or spring elements, may be used and configured to limit energy dissipation to an acceptable limit, thereby reducing wear.

[0076] When the damping system 700 is arranged, a high normal force and / or static or dynamic friction coefficient will prevent relative sliding motion between the first element 710 and the second element 712, and in such cases, no energy is dissipated. In contrast, a low normal force and / or static or dynamic friction coefficient can result in low friction, and sliding will occur, but less energy will be dissipated. Furthermore, a low normal force and / or static or dynamic friction coefficient can cause friction at the outer surface of the second element 712 (e.g., between the second element 712 and the formation 708) to be higher than that between the first element 710 and the second element 712, resulting in a relative velocity between the first element 710 and the second element 712 that is not equal to or close to zero but falls within the range of the average velocity between the downhole system 702 and the formation 708. Therefore, the normal force and static or dynamic friction coefficient, as well as the arrangement of the damper elements relative to the excited modes and mode shapes (e.g., by using the adjusting element 716), can be adjusted to achieve optimized energy dissipation.

[0077] This can be achieved by adjusting the normal force F. N The static friction coefficient μ0 and the dynamic friction coefficient are determined by the arrangement of small damper elements relative to the excited mode shape, or by a combination thereof. The normal force F can be adjusted in the following ways. N The positioning adjustment element 716 and / or the actuator generates a force on one of the first and second elements, with a component perpendicular to the contact surfaces of the first and second elements, thereby adjusting the pressure state around the first and second elements, or increasing or decreasing the area of ​​pressure application. For example, increasing the external pressure acting on the second element (such as mud pressure) will also increase the normal force F. N The pressure of the downhole mud can be adjusted by regulating the mud pump on the surface (e.g., Figure 1 This can be achieved using the mud pump 34 shown or other equipment (such as bypasses, valves, fluctuation suppressors) that affects mud pressure on the surface or downhole. The normal force can be adjusted to a harmonic with the same frequency as the natural frequency of the excited mode shape, and thus has a low normal force value for low acceleration of inertial mass and a high normal force value for low acceleration of inertial mass, and thus allows sliding motion with low acceleration values.

[0078] The normal force F can also be adjusted by a biasing element (not shown) such as a spring element. N The biasing element applies a force to the second element 712, for example, a force in an axial direction away from or towards the first element 710. The normal force F can also be applied in a controlled manner based on input received from the sensor. NThe adjustment is as follows. For example, a suitable sensor (not shown) can provide one or more parameter values ​​to the controller (not shown), which are related to the relative motion of the first element 710 and the second element 712 or the temperature of one or both of the first element 710 and the second element 712. Based on these parameter values, the controller can provide an increase or decrease in the normal force F. N The controller can provide instructions, for example, to reduce the normal force F if the temperature of one or both of the first element 710 and the second element 712 exceeds a threshold temperature. N The controller provides instructions to prevent damage to one or both of the first element 710 and the second element 712 due to high temperatures. Similarly, for example, if the distance, velocity, or acceleration of the second element 712 relative to the first element 710 exceeds a threshold, the controller can provide an increase or decrease in the normal force F. N The instructions ensure optimal energy dissipation. The normal force F can be controlled by monitoring parameter values. N To achieve the desired result within a time period. For example, controllable normal force F N To provide optimal energy dissipation while keeping the temperature of one or both of the first element 710 and the second element 712 below a threshold during or during the drilling process.

[0079] Additionally, the static or dynamic coefficient of friction can be adjusted by using different materials, such as, but not limited to, materials with different stiffness, roughness, and / or lubricity. For example, surfaces with higher roughness generally increase the coefficient of friction. Therefore, the coefficient of friction can be adjusted by selecting a material with an appropriate coefficient of friction for at least one of the first and second elements, or a portion thereof. The materials of the first and / or second elements can also affect the wear of the first and second elements. To keep the wear of the first and second elements low, it is advantageous to select materials capable of withstanding the friction generated between the first and second elements. The inertia, coefficient of friction, and expected acceleration amplitude (e.g., varying with mode shape and eigenfrequency) of the second element 712 are parameters that determine the dissipated energy and also need to be optimized. The critical mode shape and acceleration amplitude can be determined by measurement or calculation, or based on other known methods as understood by those skilled in the art. Examples are finite element analysis, transfer matrix method, or finite difference method, and modal analysis or analytical modes based thereon. It is optimal to place the friction damper where high relative displacement or acceleration is expected.

[0080] Now turning Figure 9A and Figure 9B An example of downhole system 900 and its corresponding modes is shown. Figure 9A This is a schematic diagram of the downhole system, showing how the mode shapes of the downhole system change with distance from the drill bit. Figure 9B It shows that it can be used Figure 9A An exemplary corresponding torsional oscillation mode shape excited during the operation of a downhole system. Figure 9A and Figure 9B The schematic diagram illustrates the potential location and arrangement of one or more components of the damping system on the downhole system 900.

[0081] like Figure 9A As schematically shown, the downhole system 900 includes various components with different diameters (and different masses, densities, configurations, etc.), and therefore, during rotation of the downhole system 900, these different components can induce various modes. Exemplary modes indicate where the highest amplitude will exist, which may require damping by applying a damping system. For example, as... Figure 9B As shown, mode shapes 902, 904, and 906 of a first torsional oscillation, a second torsional oscillation, and a third torsional oscillation of a downhole system 900 are illustrated. Based on knowledge of mode shapes 902, 904, and 906, the location of the first element of the damping system can be optimized. Damping may be required and / or implemented when the amplitudes of mode shapes 902, 904, and 906 are at their maximum values ​​(peak values). Therefore, two potential locations for attaching or mounting the damping system of this disclosure are exemplarily shown.

[0082] For example, the first damping position 908 is close to the drill bit of the downhole system 900 and primarily dampes the first and third torsional oscillations (corresponding to modes 902 and 906) and provides some damping for the second torsional oscillation (corresponding to mode 904). That is, the first damping position 908 is approximately at the peak of the third torsional oscillation (corresponding to mode 906), close to the peak of the first torsional oscillation mode 902, and approximately halfway to the peak of the second torsional oscillation mode 904.

[0083] The second damping position 910 is arranged to again primarily provide damping for the third torsional oscillation mode 906 and some damping for the first torsional oscillation mode 902. However, in the second damping position 910, damping of the second torsional oscillation mode 904 does not occur because the second torsional oscillation mode 904 is close to zero at the second damping position 910.

[0084] Despite Figure 9A and Figure 9B Only two locations are shown for arranging the damping system of this disclosure, but the implementation is not so limited. For example, any number and arrangement of damping systems can be installed along the downhole system to provide torsional vibration damping to the downhole system. Examples of preferred installation locations for the dampers are where one or more of the mode shapes are expected to exhibit high amplitudes.

[0085] Due to the high amplitude at the drill bit, a good location for a damper is, for example, close to or even inside the drill bit. Furthermore, the first and second elements are not limited to a single body, but can take any number of various configurations to achieve the desired damping. That is, multiple bodies (multi-body) first or second elements (e.g., friction damping devices) can be used, where each body has the same or different normal force, coefficient of friction, and moment of inertia. Such a multi-body element arrangement can be used, for example, if it is uncertain which mode shape and corresponding acceleration are expected at a given location along the downhole system.

[0086] For example, two or more component bodies can be used to dissipate energy by achieving different relative sliding motions between them. The multiple bodies of the first component can be selected and assembled using different static or dynamic coefficients of friction, angles between contact surfaces, and / or may have other mechanisms affecting the amount of friction and / or the transition between viscosity and sliding. Such configurations can be used to dampen several amplitude levels, excited mode shapes, and / or natural frequencies.

[0087] For example, turning Figure 10 A schematic diagram of a damping system 1000 according to one embodiment of the present disclosure is shown. The damping system 1000 can be compared with the above-described damping system. Figure 7 The damping system 1000 operates in a similar manner to that shown and described. The damping system 1000 includes a first element 1010 and a second element 1012. However, in this embodiment, the second element 1012, mounted to the first element 1010 of the downhole system 1002, is formed by a first body 1018 and a second body 1020. The first body 1018 has a first contact surface 1022 between the first body 1018 and the first element 1010, and the second body 1020 has a second contact surface 1024 between the second body 1020 and the first element 1010. As shown, the first body 1018 and the second body 1020 are separated by a gap 1026. The gap 1026 is provided to prevent interaction between the first body 1018 and the second body 1020, allowing them to operate independently of each other (e.g., move) or not to interact directly with each other. In this embodiment, the first body 1018 has a first static friction coefficient or dynamic friction coefficient μ1 and a first force F perpendicular to the first contact surface 1022. N 1. The second body 1020 has a second static friction coefficient or dynamic friction coefficient μ2 and a second force F perpendicular to the second contact surface 1024. N2 Furthermore, the first body 1018 may have a first moment of inertia J1, and the second body 1020 may have a second moment of inertia J2. In some embodiments, the first static friction coefficient or dynamic friction coefficient μ1 and the first normal force F... NAt least one of the first moment of inertia J1 and the second static friction coefficient or dynamic friction coefficient μ2, and the second normal force F are chosen to be different from the second static friction coefficient or dynamic friction coefficient μ2 and the second normal force F, respectively. N2 And the second moment of inertia J1. Therefore, the damping system 1000 can be configured to take into account multiple different mode shapes at essentially a single location along the downhole system 1002.

[0088] Turn now Figure 11 A schematic diagram of a damping system 1100 according to one embodiment of the present disclosure is shown. The damping system 1100 can operate in a manner similar to that shown and described above. However, in this embodiment, the second element 1112 installed to the first element 1110 of the downhole system 1102 is formed by a first body 1118, a second body 1120, and a third body 1128. The first body 1118 has a first contact surface 1122 between the first body 1118 and the first element 1110, the second body 1120 has a second contact surface 1124 between the second body 1120 and the first element 1110, and the third body 1128 has a third contact surface 1130 between the third body 1128 and the first element 1110. As shown, the third body 1128 is located between the first body 1118 and the second body 1120. In this embodiment, the three bodies 1118, 1120, and 1128 are in contact with each other, and therefore they can have a normal force and a static friction coefficient or a dynamic friction coefficient.

[0089] The contact between the three bodies 1118, 1120, and 1128 can be established, maintained, or supported by an elastic connecting element (such as a spring element) between two or more of the bodies 1118, 1120, and 1128. Alternatively, the first body 1118 may have a first static or dynamic coefficient of friction μ1 and a first force F at the first contact surface 1122. N 1. The second body 1120 may have a second static friction coefficient or dynamic friction coefficient μ2 and a second force F at the second contact surface 1124. N2 Furthermore, the third body 1128 may have a third static friction coefficient or dynamic friction coefficient μ3 and a third force F at the third contact surface 1130. N3 .

[0090] Alternatively, the first body 1118 and the third body 1128 may have a fourth force F between them at the contact surface between the first body 1118 and the third body 1128. N13 and the fourth static friction coefficient or dynamic friction coefficient μ 13 Similarly, the third body 1128 and the second body 1120 may have a fifth force F between them at the contact surface between the third body 1128 and the second body 1120. N32And the fifth static friction coefficient or dynamic friction coefficient μ 32 .

[0091] Furthermore, the first body 1118 may have a first moment of inertia J1, the second body 1120 may have a second moment of inertia J2, and the third body 1128 may have a third moment of inertia J3. In some embodiments, the static friction coefficient or dynamic friction coefficient μ1, μ2, μ3, μ 13 μ 32 Force F N1 F N2 F N3 F 13 F 32 The moments of inertia J1, J2, and J3 can be chosen to be different from each other, such that for at least a subrange of the relative velocities of the first element 1110, the first body 1118, the second body 1120, and the third body 1128, the product μ i ·F i (Where i = 1, 2, 3, 13, 32) are different. In addition, the static or dynamic friction coefficient and normal force between adjacent bodies can be selected to achieve different damping effects.

[0092] Although a limited number of embodiments and specific shapes, relative dimensions, and quantities of elements have been shown and described, those skilled in the art will understand that the damping system of this disclosure can take any configuration. For example, shape, size, geometry, radial arrangement, contact surfaces, number of bodies, etc., can be selected to achieve the desired damping effect. Although in Figure 11 In the arrangement shown, the first body 1118 and the second body 1120 are connected to each other through frictional contact with the third body 1128; however, such arrangement and description are not limiting. The connection between the first body 1118 and the second body 1120 can also be achieved by hydraulic, electrical, or mechanical coupling devices or mechanisms. For example, the mechanical coupling between the first body 1118 and the second body 1120 can be achieved by a rigid or elastic connection between the first body 1118 and the second body 1120.

[0093] Turn now Figure 12A schematic diagram of a damping system 1200 according to one embodiment of the present disclosure is shown. The damping system 1200 can operate in a manner similar to that shown and described above. However, in this embodiment, a second element 1212 of the damping system 1200 is partially fixedly attached to or connected to a first element 1210. For example, as shown in this embodiment, the second element 1212 has a fixed portion 1232 (or fixed end) and a movable portion 1234 (or movable end). The fixed portion 1232 is fixed to the first element 1210 along a fixed connection 1236, and the movable portion 1234 is in frictional contact with the first element 1210 across a contact surface 1214 (similar to frictional contact with the first element 1210 relative to the first element 1210). Figure 10 The first element 1010 and the second element 1012 are in frictional contact (described).

[0094] Movable parts 1234 can have the ability to interact with Figure 9B The movable portion may be longer than one-tenth the distance between the maximum and minimum values ​​of any modal vibration mode that may have been calculated for a particular drilling assembly. In another example, in some embodiments, the movable portion may be longer than one-quarter the distance between the maximum and minimum values ​​of any modal vibration mode that may have been calculated for a particular drilling assembly. In yet another example, in some embodiments, the movable portion may be longer than half the distance between the maximum and minimum values ​​of any modal vibration mode that may have been calculated for a particular drilling assembly. In yet another example, in some embodiments, the movable portion may be longer than the distance between the maximum and minimum values ​​of any modal vibration mode that may have been calculated for a particular drilling assembly.

[0095] Therefore, even if the exact location of the modal maximum or minimum may not be known during downhole deployment, it can be ensured that the second element 1212 is in frictional contact with the first element 1210 at the location of maximum amplitude to achieve optimized damping. Although a specific arrangement is used to illustrate, those skilled in the art will understand that other arrangements of the partially fixed first element are possible without departing from the scope of this disclosure. For example, in a non-limiting embodiment, the fixed portion may be located in a more central part of the first element, such that the first element has two movable portions (e.g., at opposite ends of the first element). Figure 12 As can be seen, the movable portion 1234 of the second element 1212 is quite elongated and can cover the modal vibration modes (such as) corresponding to the length of the movable portion 1234 of the second element 1212. Figure 9BPart of the modal modes 902, 904, 906. An elongated second element 1212 that is in frictional contact with the first element 1210 is preferable to a shorter second element because a shorter second element can be located in an undesirable portion of the modal mode, such as in a damped position 910 where the second modal mode 904 has little or even zero damping, as described above relative to... Figure 9B As explained, the use of the elongated second element 1212 ensures that at least a portion of the second element is located at a certain distance from a position where one or more of the modal modes are zero or at least close to zero. Figures 13 to 19 and Figures 21 to 22 Further examples of elongated second elements that frictionally contact the first element are shown. In some embodiments, the elongated second element may be elastic, such that the movable portion 1234 can move relative to the first element 1210, while the fixed portion 1232 remains stationary relative to the first element 1210. In some embodiments, the second element 1212 may have multiple contact points at multiple locations on the first element 1210.

[0096] In the above embodiments, and in the damping system according to this disclosure, the first element is temporarily fixed to the second element due to frictional contact. However, when the vibration of the downhole system increases and exceeds a threshold, for example when the inertial force exceeds the static friction, the first element (or a portion thereof) moves relative to the second element, thus providing damping. That is, when the HFTO increases within the downhole system to above a predetermined threshold (e.g., a threshold for amplitude, distance, velocity, and / or acceleration), the damping system will operate automatically, and therefore the embodiments provided herein include passive damping systems. For example, embodiments include passive damping systems that operate automatically without utilizing additional energy, thus eliminating the need for additional energy.

[0097] Turn now Figure 13 A schematic diagram of a damping system 1300 according to one embodiment of the present disclosure is shown. In this embodiment, the damping system 1300 includes one or more elongated first elements 1310a, 1310b, 1310c, 1310d, 1310e, 1310f, each elongated first element disposed within and in contact with a second element 1312. Each of the first elements 1310a, 1310b, 1310c, 1310d, 1310e, 1310f may be positioned in the axial tool direction (e.g., in relation to...). Figure 13The cross-section shown has a length (vertical direction) and optionally fixed points, at which corresponding first elements 1310a, 1310b, 1310c, 1310d, 1310e, 1310f are fixed to the second element 1312. For example, the first elements 1310a, 1310b, 1310c, 1310d, 1310e, 1310f can be fixed at the corresponding upper end, middle portion, lower end, or multiple fixed points of different first elements 1310a, 1310b, 1310c, 1310d, 1310e, 1310f, or multiple points of a given single first element 1310a, 1310b, 1310c, 1310d, 1310e, 1310f. Furthermore, as... Figure 13 As shown, the first elements 1310a, 1310b, 1310c, 1310d, 1310e, and 1310f may optionally be biased or engaged to the second element 1312 by a biasing element 1338 (e.g., by applying a force having a component toward the second element 1312 via a biasing spring element or a biasing actuator). Each of the first elements 1310a, 1310b, 1310c, 1310d, 1310e, and 1310f may be arranged and selected to have the same or different normal forces, static or dynamic friction coefficients, and moments of inertia, thereby achieving various damping configurations.

[0098] In some embodiments, the first element may be substantially uniform in material, shape, and / or geometry along its length. In other embodiments, the first element may vary in shape and geometry along its length. For example, refer to... Figure 14 A schematic diagram of a damping system 1400 according to an embodiment of the present disclosure is shown. In this embodiment, a first element 1410 is arranged relative to a second element 1412, and the first element 1410 has a tapered and / or helical arrangement relative to the second element 1412. Thus, in some embodiments, the geometry or shape of the first element or a portion of the second element may change along its length relative to the second element, and such changes may also occur in the circumferential span around or relative to the second element and / or relative to the tool body or downhole system.

[0099] Turn now Figure 15A schematic diagram of another damping system 1500 according to one embodiment of the present disclosure is shown. In the damping system 1500, a first element 1510 is a toothed (threaded) body that mates within a threaded second element 1512. The contact between the teeth (threads) of the first element 1510 and the threads of the second element 1512 provides frictional contact between the two elements 1510, 1512 to achieve damping as described herein. Due to the inclined surface of the first element 1510, the first element 1510 will begin to move under axial vibration and / or torsional vibration. Furthermore, the movement of the first element 1510 in the axial or circumferential direction will also produce circumferential or axial movement in this configuration, respectively. Therefore, utilizing Figure 15 The arrangement shown allows axial vibration to be used to mitigate or dampen torsional vibration, and vice versa. The locations of axial and torsional vibrations can differ. For example, while axial vibration may be uniformly distributed along the drilling assembly, torsional vibration may follow the pattern described above relative to... Figures 9A to 9B The modal vibration modes are discussed. Therefore, regardless of where the vibration occurs, Figure 15 The configuration shown can be used to dampen torsional vibrations by using the movement of the first element 1510 relative to the second element 1512 caused by axial vibration (and vice versa). As shown, an optional fastening element 1540 (e.g., a bolt) can be used to adjust the contact pressure or normal force between the two elements 1510, 1512, thus adjusting the friction and / or other damping characteristics of the damping system 1500.

[0100] Turn now Figure 16 A schematic diagram of a damping system 1600 according to one embodiment of the present disclosure is shown. The damping system 1600 includes a first element 1610, which is a rigid rod fixed at one end within a second element 1612. In this embodiment, the rod end 1610a is arranged to frictionally contact the second element stop 1612a, thus providing damping as described in the embodiment of the present disclosure. The normal force between the rod end 1610a and the second element stop 1612a can be adjusted, for example, by a threaded connection between the rod end 1610a and the first element 1610. Furthermore, the stiffness of the rod can be selected to optimize damping or to advantageously influence the mode shape to provide greater relative displacement. For example, selecting a rod with lower stiffness will result in a higher amplitude and higher energy dissipation of the torsional oscillations of the first element 1610.

[0101] Turn now Figure 17A schematic diagram of a damping system 1700 according to one embodiment of the present disclosure is shown. The damping system 1700 includes a first element 1710 frictionally attached or connected to a second element 1712, the second element being arranged as a rigid rod and fixedly connected (e.g., by welding, screwing, brazing, adhesion, etc.) to an outer tube 1714, such as a drill collar, at a fixed connection 1716. In one aspect, the rod may be a tube comprising electronic components, power supplies, storage media, batteries, microcontrollers, actuators, sensors, etc., susceptible to wear due to HFTO. That is, in one aspect, the second element 1712 may be a probe, such as a probe for measuring orientation information, including one or more of a gravimeter, gyroscope, and magnetometer. In this embodiment, the first element 1710 is arranged to frictionally contact the fixed rod structure of the second element 1712, and to move or oscillate relative to and along the fixed rod structure, thus providing damping as described in the embodiment of the present disclosure. While the first element 1710 is in Figure 17 The element 1710 is shown as relatively small compared to the damping system 1700, but this is not intended to be limiting in this respect. Therefore, the first element 1710 can be of any size and can have the same outer diameter as the damping system 1700. Furthermore, the position of the first element 1710 can be adjustable to move it closer to the maximum modal value, thereby optimizing damping reduction.

[0102] Turn now Figure 18 A schematic diagram of a damping system 1800 according to one embodiment of the present disclosure is shown. The damping system 1800 includes a first element 1810 that is frictionally movable along a second element 1812. In this embodiment, the first element 1810 is arranged to have an elastic spring element 1842 (such as a coil spring or other element or device) to engage the first element 1810 with the second element 1812, thus providing a restoring force when the first element 1810 has moved and deflected relative to the second element. This restoring force is directed to reduce the deflection of the first element 1810 relative to the second element 1812. In such embodiments, the elastic spring element 1842 may be arranged or tuned to the resonant and / or critical frequency (e.g., the lowest critical frequency) of the oscillating system including the first element 1810 and the elastic spring element 1842.

[0103] Turn now Figure 19 A schematic diagram of a damping system 1900 according to one embodiment of the present disclosure is shown. The damping system 1900 includes a first element 1910 that is frictionally movable about a second element 1912. In this embodiment, the first element 1910 is arranged with a first end 1910a having a first contact (e.g., a first end normal force F). Ni The first end static friction coefficient or dynamic friction coefficient μi and the first moment of inertia J i ), and has a second contact at the second end 1910b (e.g., the normal force F at the second end). Ni The second end static friction coefficient or dynamic friction coefficient μ i Second end moment of inertia J i In some such embodiments, the type of interaction between the respective first end 1910a or second end 1910b and the second element 1912 may have different physical characteristics. For example, one or both of the first end 1910a and the second end 1910b may have viscous contact / engagement, and one or both may have sliding contact / engagement. The arrangement / construction of the first end 1910a and the second end 1910b may be configured to provide damping as described in embodiments according to this disclosure.

[0104] Advantageously, the embodiments provided herein relate to systems for mitigating high-frequency torsional oscillations (HFTO) in downhole systems by applying a damping system mounted on a rotating tubing string (e.g., a downhole tubing string or drill string). A first element of the damping system is at least partially frictionally connected to move circumferentially relative to the axis of the drill string (e.g., frictionally connected to rotate about the axis of the drill string). In some embodiments, a second element may be part of the drilling system or downhole tool assembly and does not need to be a separately installed component or weight. The second element, or a portion thereof, is connected to the downhole system in such a way that the relative motion between the first and second elements has zero or near-zero relative velocity (i.e., no relative motion or slow relative motion) in the absence of HFTO. However, when HFTO occurs above different acceleration values, relative motion between the first and second elements is possible and alternating positive and negative relative velocities are achieved. In some embodiments, the second element may be a mass or weight connected to the downhole system. In other embodiments, the second element may be part of the downhole system (e.g., part of the drilling system or BHA, such as the remainder of the downhole system providing the functions described herein) and there is friction between the first and second elements.

[0105] As described above, the second element of the damping system is selected or configured such that when there is no vibration in the drill string (i.e., HFTO), the second element is frictionally connected to the first element via static friction. However, when vibration (HFTO) is present, the second element moves relative to the first element and as described above relative to... Figure 2As described, the frictional contact between the first and second elements is reduced, allowing the second element to rotate (move) relative to the first element (and vice versa). During movement, the first and second elements dissipate energy, thereby mitigating HFTO. The damping system, particularly its first element, has a specific position, weight, external force, and size to achieve damping at one or more specific or predefined vibration modes / frequencies. As described herein, the first element is fixedly connected in the absence of HFTO vibration, but is subsequently able to move in the presence of certain accelerations (e.g., according to the HFTO mode), thus achieving HFTO damping through zero-crossing of relative velocity (e.g., switching between positive and negative relative rotational velocities).

[0106] In the various configurations discussed above, sensors can be used to estimate and / or monitor the efficiency of the damper and the energy dissipated. For example, measurements of displacement, velocity, and / or acceleration near the contact point or surface of the two interacting bodies, in conjunction with force or torque sensors, can be used to estimate relative motion and calculate the dissipated energy. For example, when the two interacting bodies are engaged by a biasing element (such as a spring element or actuator), the force can also be known without measurement. The dissipated energy can also be derived from temperature measurements. Such measurements can be transmitted to a controller or operator, allowing adjustment of parameters such as normal force and / or the coefficient of static or kinetic friction to achieve higher energy dissipation. For example, measured and / or calculated values ​​of displacement, velocity, acceleration, force, and / or temperature can be sent to a controller (such as a microcontroller) having a set of instructions stored in a storage medium, based on which the controller adjusts and / or controls at least one of the force and / or the coefficient of static or kinetic friction that engages the two interacting bodies. Preferably, the adjustment and / or control are performed during the drilling process to achieve optimal HFTO damping results.

[0107] Although the embodiments described herein have been described with reference to specific accompanying drawings, it should be understood that various changes may be made and equivalents may be substituted for elements therein without departing from the scope of this disclosure. Furthermore, many modifications will be made to adapt particular apparatus, situations, or materials to the teachings of this disclosure without departing from the scope of this disclosure. Therefore, it is contemplated that this disclosure is not limited to the specific embodiments disclosed, but rather will include all embodiments falling within the scope of the following description of the appended claims or possible embodiments.

[0108] Severe vibrations in the drill string and downhole assembly can be caused by cutting forces at the drill bit or mass imbalances in downhole tools (such as drill motors). Among other negative effects are reduced drilling rates, decreased measurement quality, and downhole malfunctions.

[0109] Different types of torsional vibrations exist. In the literature, torsional vibrations are mainly distinguished as viscous / slippage throughout the drilling system and high-frequency torsional oscillations (HFTO). Both are primarily excited by self-excitation mechanisms arising from the interaction between the drill bit and the formation. The main difference between viscous / slippage and HFTO is the frequency and typical mode shape: HFTO has frequencies above 50 Hz, compared to frequencies below 1 Hz for viscous / slippage. Furthermore, the excited mode shape of viscous / slippage is the first mode shape throughout the drilling system, while the mode shape of HFTO is typically confined to a small portion of the drilling system and has a relatively high amplitude at the drill bit.

[0110] Due to its high frequency, HFTO corresponds to high acceleration and torque values ​​along the BHA and can have a damaging effect on electronic devices and mechanical components. Based on the theory of self-excitation, increased damping can alleviate HFTO up to a certain limit of the damping value (this is due to the self-excitation instability and can be interpreted as negative damping of the associated modes).

[0111] One damping concept is based on friction. Friction between two components in a BHA or drill string can dissipate energy and reduce the level of torsional oscillations.

[0112] Based on this concept, the inventors discuss the design principle that they believe is most suitable for damping caused by friction. Damping should be achieved by frictional force, wherein the operating point of the frictional force relative to the relative velocity must be... Figure 2 The area around point 204 is shown. This operating point experiences high energy dissipation due to the implementation of frictional hysteresis, while... Figure 2 Point 202 will cause energy input into the system.

[0113] As discussed above, the friction between the drilling system and the borehole does not produce significant additional damping in the system. This is because the relative velocity between the contact surfaces (e.g., the stabilizer and the borehole) does not have a zero average value. The two interacting bodies of a friction damper must have an average velocity or rotational velocity relative to each other that is small enough that the HFTO causes a sign change in the relative velocity of the two interacting bodies. In other words, the maximum value of the relative velocity between the two interacting bodies produced by the HFTO needs to be higher than the average relative velocity between the two interacting bodies.

[0114] Energy dissipation occurs only during the sliding phase at the interface between the damping device and the drilling system. Sliding occurs when the inertial force exceeds the limit between viscosity and sliding (i.e., static friction): F R >μ0·F N(Where static friction equals the static friction coefficient multiplied by the normal force between the two contact surfaces). The normal force and / or the static or dynamic friction coefficient can be adjusted to achieve optimal or desired energy dissipation. Adjusting at least one of the normal force and the static or dynamic friction coefficient can improve energy dissipation caused by the damping system.

[0115] As discussed herein, the friction dampers should be positioned in regions of high HFTO acceleration, load, and / or relative motion. Because different modes can be affected, a design that mitigates all HFTO modes is preferred (e.g., Figure 9A and Figure 9B ).

[0116] An equivalent can be used as the friction damper tool of this disclosure. A slotted drill collar 2100 can be used, such as... Figure 21 and Figure 22 As shown. Figure 22 A cross-sectional view of a slotted drill collar 2100 is shown. In a non-limiting embodiment, the slotted drill collar 2100 has high flexibility and will cause greater deformation without the addition of a friction device 2102. Higher speed will result in higher centrifugal force, which will push the friction device 2102 into the slot under optimized normal force to allow for high frictional damping. Other factors that can be optimized in this configuration are the number and geometry of the slots and the geometry of the damping device. The additional normal force can be provided by a spring element 2104 as discussed above (e.g., Figure 22 (as shown), actuator and / or applied by centrifugal force.

[0117] The advantage of this principle is that the friction device is directly integrated into the force flow. The torsion of the drill collar caused by the excited HFTO mode and corresponding mode shape will be partially supported by the friction device, which will move up and down during one cycle of vibration. The high relative motion, along with the optimized friction coefficient and normal force, will result in high energy dissipation.

[0118] The objective is to prevent an increase in the amplitude of the HFTO (in this case, represented by the tangential acceleration amplitude). The (modal) damping that must be added by the friction damper system to each unstable torsional mode requires an energy input higher than the energy input to the system. This energy input does not occur instantaneously, but rather over multiple cycles until the worst-case amplitude (zero RPM at the drill bit) is reached.

[0119] According to this concept, a relatively short drill collar can be used because the friction damper utilizes relative motion along the distance from the drill bit. A high tangential acceleration amplitude is not required; only some deflection (“torsion”) of the drill collar is needed, which will be achieved in almost every place along the BHA. The drill collar and damper should have a mass-stiffness ratio (“impedance”) similar to that of the BHA. This will allow the mode shape to propagate in the friction drill collar. High damping will be achieved, which will alleviate the HFTO by adjusting the parameters discussed above (normal force due to springs, etc.). An advantage compared to other friction damper principles is that the friction device is directly applied to the force flow of the HFTO mode deflection. The relatively high relative velocity between the friction device and the drill collar will cause high energy dissipation.

[0120] The damper will be highly efficient and effective for various applications. HFTO (High-Frequency Friction Tolerance) causes high costs due to extensive repair and maintenance work, reliability issues accompanied by non-productive time, and a small market share. The proposed friction damper will operate both below (decoupling the HFTO) and above the motor. It can be installed in every location within the BHA (Body Harness), and if the mode shape propagates to that point, this will also be included in the arrangement above the BHA. If the mass and stiffness distributions are relatively similar, the mode shape will propagate throughout the entire BHA. The optimal arrangement can be determined, for example, by a torsional oscillation advisor, which allows for the calculation of critical HFTO modes and corresponding mode shapes.

[0121] Furthermore, as described above, due to the high amplitude at the drill bit, a location for the damper, as described herein, can be positioned within or near the drill bit, such as within or on the drill bit support assembly. That is, according to some embodiments of this disclosure, the damper can be integrated into and become part of the drill bit support assembly. In such embodiments, the distance from the drill bit is essentially zero. As described herein, the drill bit support assembly includes, but is not limited to, a drill bit housing, a drive shaft, sleeves associated with drill bit securing and driving / operating, steering units and / or elements associated with manipulating drilling operations, a bending mechanism for steering in a bending motor, elements engaging the borehole wall, non-rotating sleeves or slowly rotating sleeves, etc. The drill bit support assembly of this disclosure can be part of a BHA including elements other than fracturing equipment, and in some cases, such equipment may be included where fracturing equipment is integrally formed with a part of the drill bit support assembly.

[0122] A steering unit (also referred to as a steering section or steering assembly) is employed and configured for drilling a directional borehole. This directional drilling may be referred to in the art as geological steering. In a non-limiting example, the steering unit includes multiple extendable members (e.g., force-applying members) located on a non-rotating sleeve (e.g., a tool sleeve), which are configured to apply selected or predetermined forces to the borehole wall for drilling the directional borehole. When forces are applied to the borehole wall, the non-rotating sleeve remains stationary or rotates only slowly relative to the borehole wall, while a drive shaft passing through the non-rotating sleeve rotates at the speed of the fracturing equipment (e.g., drill bit RPM). The extendable members may be operated by an actuation mechanism (e.g., a hydraulic actuation mechanism, an electric actuation mechanism, or an electromechanical actuation mechanism).

[0123] In some such embodiments, the damper may be formed by a mass or inertia member connected to the drill bit support assembly solely by a damping force or damping torque. The damping force may be generated, for example, but not limited to, viscous damping, frictional damping, hydraulic damping, magnetic damping (e.g., eddy current damping), piezoelectric (shunt) damping, etc. In some such embodiments, the damper may be combined with a spring that will activate a tuned mass damper or a tuned friction damper. In these cases, the damper's resonant frequency will be tuned to the resonant frequency of the mode to be damped.

[0124] As discussed above, the analysis has shown that damping increases proportionally with the effective rotational inertia and quadratically with the mass-normalized mode shape at the drill bit. The additional constant factor depends on the type of damping. Frictional damping with inertial dampers is theoretically frequency-independent, while hydraulic dampers exhibit a certain frequency dependence. This trade-off also applies to other types of damping and can be influenced by different parameters of the force (e.g., by harmonicly adjusting the normal force of the friction damper configuration, selecting a fluid whose properties change with the relative velocity of the components, etc.). As mentioned, the drill bit box or drill bit is one location where inertial dampers are used, which can be advantageous because the critical mode typically has the maximum amplitude at the drill bit (e.g., as...). Figure 9B (As shown). An exemplary critical mode is at 248 Hz, with maximum amplitude at the drill bit; however, various other modes / frequencies may be critical depending on specific configurations and downhole operations. That is, the critical mode can depend on various considerations, and only the 248 Hz mode is described as an example for illustrative purposes. It is important to note that excitability theoretically also increases quadratically with the amplitude of the mode shape at the drill bit. Furthermore, the amount of damping required to mitigate vibration also increases quadratically with the mode shape at the drill bit.

[0125] In a non-limiting embodiment of the damper located near but not within the drill bit, the friction damper can be a closed loop having any mode of vibration, connected to the drill bit support assembly and configured to rotate torsionally. In another embodiment, the damper can be a linear mass connected tangentially to or within the drill bit support assembly and configured to effectively induce rotational forces. Several individual dampers can be mounted and configured around or within the drill bit support assembly (i.e., near the end of the drill string). In another configuration, the damper can be formed by two forcibly connected parts of the drill bit support assembly connected to different axial locations on the drill bit support assembly (e.g., near the drill bit connector and near the drive shaft connector). The connection at the different axial locations results in relative movement between the two forcibly connected parts. Examples of this configuration may include, for example, threaded connections to opposing contact surfaces.

[0126] For example, turning Figure 23 A schematic diagram of a drill bit support assembly 2300 is shown. The drill bit support assembly 2300 includes a drill bit holder 2302 configured to receive a drill bit within a drill bit cavity 2304. The drill bit cavity 2304 is configured (e.g., shaped, sized, etc.) to receive a drill bit or other fracturing device. The drill bit holder 2302 is configured to hold and, in some configurations, drive the operation of the drill bit mounted within the drill bit cavity 2304, as will be understood by those skilled in the art. The drill bit or other fracturing device may be configured to cut material (e.g., rock) from the formation during drilling operations.

[0127] As shown, the drill bit housing 2302 is mounted to the drive shaft 2306 within the drill bit support assembly 2300. The drive shaft 2306 is rotatable to drive the operation (e.g., rotation) of the drill bit mounted in the drill bit cavity 2304 / within the drill bit cavity. In operation, drilling torque is transmitted from the drive shaft 2306 to the drill bit housing 2304 via a torque sleeve 2308 and a cap sleeve 2310. A threaded connection 2312 generates axial preload between the drive shaft 2306 and the drill bit housing 2302. Torque is transmitted frictionally between the various components of the drill bit support assembly 2300, which may depend on the axial surface pressure of the contact surfaces, the coefficient of friction, and the radius relative to the tool axis Ax. The first shoulder surface 2314 of the torque sleeve 2308 that contacts the drive shaft 2306 may be coated with a friction-enhancing layer (e.g., a diamond material), which enables torque transmission to be increased by a multiplicative factor, as those skilled in the art will understand. The second shoulder surface 2316, which provides contact between the drive shaft 2306 and the drill housing 2302, can be configured to increase tightening torque (MUT) capability. Due to the coating at the first shoulder surface 2314, relative movement of the torque sleeve 2308 relative to, for example, the drive shaft 2306 is not expected. The cap sleeve 2310 has a larger radius, i.e., relative to the tool axis Ax, than the torque sleeve 2308, and the torque that can be transmitted is greater at the first shoulder surface 2314 than at the second shoulder surface 2316.

[0128] The typical design of the drill bit box, or so-called lower drive shaft, is a double-shoulder screw thread, such as... Figure 23 The example is shown. However, in some alternative configurations, the drill box, torque sleeve, and / or drill bit may be joined together as a single part / component. In this configuration, relative movement occurs between the two shoulders (e.g., Figure 23 The first shoulder surface 2314 and the second shoulder surface 2316 are shown. Therefore, it is not possible to apply a friction-increasing coating to the first shoulder surface, as described above. As a result, this leads to a significant reduction in transmittable torque due to the reduced coefficient of friction and smaller radius of influence.

[0129] As shown in the figure, the drive shaft 2306 and torque sleeve 2308 can be accommodated within the tool sleeve 2318. The tool sleeve 2318 can be a non-rotating sleeve or a slowly rotating sleeve, as those skilled in the art will understand. The tool sleeve 2318 can be configured to engage or connect to the BHA or other downhole components and / or tool string.

[0130] As described above, various types of dampers can be incorporated into various aspects of a drilling system. In the exemplary embodiment shown, the drill bit support assembly 2300 includes a damper element 2320, exemplarily shown as a rotational inertia element. In this embodiment, the damper element 2320 is rotationally decoupled via various bearings 2322 (e.g., radial, such as needle roller bearings or PDC bearings and / or axial bearings). The damper element 2320 is configured to be free and rotatable on the drill bit support assembly 2300 (e.g., relative to the drill bit housing 2302 and / or torque sleeve 2308). The damper element 2320 can be maximized through high-density materials and geometries with specific characteristics. For example, such as... Figure 23 As shown, the volume of damper element 2320 can be selected and / or optimized in a sense that the mass of damper element 2320 has a specific or defined radial distance from the tool axis Ax. For example, as shown, the bearing 2322 (and friction contact) can be arranged radially closer to the tool axis Ax than the damper element 2320 to allow space and optimize the cover sleeve 2310 and damper element 2320. Such space allows ensuring that all aspects of the damping system can withstand the expected loads during operation and allows the geometry and material of damper element 2320 to be selected to maximize rotational inertia and achieve the desired damping.

[0131] In some embodiments, as shown, an axial spring 2324 may be arranged to apply an axial force to the damper element 2320. In this exemplary configuration, the axial spring 2324 is arranged to transmit the axial force to the damper element 2320 via a bearing 2322 (e.g., an axial bearing) and to the friction surface 2326 between the damper element 2320 and the drill housing 2302. In some embodiments, the friction surface 2326 may be replaced by any other type of damping force mechanism. The axial contact pressure at the friction surface 2326 and the existing coefficient of friction create a frictional connection between the damper element 2320 and the drill housing 2302. The spring stiffness of the axial spring 2324 and the coefficient of friction at the friction surface 2326 can be selected to achieve maximum damping relative to the amplitude without compromising the tool life of the drill support assembly 2300 and / or the drill bit mounted to it.

[0132] like Figure 23As shown, damper element 2320 is encapsulated by cap sleeve 2310. Cap sleeve 2310 is selected to withstand external hydrostatic pressure, which may be based on wall thickness and may take into account the outer diameter of damper element 2320. In some embodiments, damper element 2320 (illustratively shown as a physical component) may be configured as a viscous damper. In some such embodiments, the mounting location of damper element 2320 may be filled with fluid, and pressure compensation may be provided by allowing design space in the size of the cap sleeve and other parts to accommodate an increase in the outer diameter of the damper element. As a non-limiting example, the fluid may be an incompressible fluid. In another embodiment, cap sleeve 2310 may be omitted. In some such embodiments, a maximum outer diameter of the damper element may be obtained, and in some such embodiments, a mud-resistant damper element will be required due to exposure to the external environment of the borehole. In this context, the inertial mass or damper element may be adjustable to cover the portion of the bending load that needs to be transmitted. The mud exposure system may also include a cap sleeve that is partially slotted to cover the bend on one hand, but also leaves more design space for the inertial mass / damper element to partially fill the slot between the cap sleeves.

[0133] In some embodiments of this disclosure, a pure rotational damper may be mounted within a drill bit support assembly, and this configuration will benefit from high modal amplitudes at or near the drill bit. Some such mountings may result in a smaller radial position of the damper element, i.e., closer to the tool axis Ax. Therefore, the smaller radius of the damper element may limit the damping effect, but this limitation can be compensated by the fact that a larger mass can be placed at the drill bit support assembly. That is, the selection of the mass and radial position relative to the tool axis Ax may be based on the desired vibration or mode to be damped and on the energy input, which may be negatively damped (e.g., as...). Figure 20 The expected excitation described (as shown) is determined.

[0134] By positioning the damper element within or at the drill bit support assembly (e.g., at or within the drill bit box or other parts of the steering assembly), sufficient damping can be achieved to minimize or eliminate downhole vibrations. This is because, in almost all cases, the mass-normalized mode amplitude of the critical mode shape is greatest at the drill bit or fracturing equipment. This can be physically explained by the fact that if the torque characteristics at the drill bit (or excitation point) are assumed to be weakened relative to the average rotational speed, the excitability and probability of excitation modes also increase quadratically with the quadratic amplitude of the mode shape at that drill bit. Incorporating a damper / damper element into the drill bit support assembly can impose a limitation on the axial length of the damper / damper element. However, because the damping is high due to the high amplitude of the mode shape at or near the drill bit, the damper / damper element can be relatively short and still achieve a sufficient damping effect. The damper at the drill bit support assembly can be less than 30cm, or 40cm, or 50cm, or 100cm, or 150cm.

[0135] According to this disclosure, one type of damping element that can be installed within or at a drill bit support assembly is a linear viscous damper. This damping element will include mass and force elements that transmit forces from the drill bit support assembly to the mass / inertia element. This damping element will have force elements that are directed, arranged, or oriented tangentially to dampen the HFTO. Based on the teachings herein, the force elements can be linear viscous or friction damping elements, as those skilled in the art will understand.

[0136] The damper element 2320 can be a single element or multiple elements / structures. For example, the damper element 2320 can be an inertia ring or other ring-shaped structure, which can be a closed or interrupted ring, such as a half-shell. In some embodiments, a half-shell (or other partial shell) may be used when a complete ring cannot be enabled due to the design or configuration of the drill bit or drill bit support assembly. The half-shell may be assembled around a radial friction contact or radial bearing (e.g., some of the bearings in bearing 2322), which may be arranged relative to the inner diameter of the damper element 2320 and similar in position and mode shape to that inner diameter. The bearings may also be separated to allow mounting of bearing 2322 and / or damper element 2320. In some embodiments, the normal force can be applied through the half-shell and controlled by the elasticity of the half-shell and the applied normal / connection force. In some embodiments, a radial wave spring shell may also be used to apply radial friction between the half-shell of, for example, the damper element and the radial friction contact.

[0137] Different geometries can be used for damper elements (e.g., inertia rings), and these different geometries can be advantageous for increasing inertia. In this sense, the density of the material chosen for the damper element can be selected to be as high as possible, such that the radius of the mass distribution is large relative to the axial axis of the drilling system or drill bit support assembly. The inertia element (or inertia semi-shell) may incorporate additional mass (inertia element) preferably mounted or arranged around the drill bit support assembly.

[0138] In some embodiments, a limiting stop may optionally be provided to prevent the ring-configured damper element from moving freely or continuously (e.g., rotating more than 10°). The normal force between the damper element and the drill housing or other parts of the drill bit support assembly can be applied radially or axially by a spring or other mechanism. Radial friction can be achieved by a spring or through the elastic design of the ring-type damper element. In some such embodiments, the double-half-shell damper element can be prestressed to achieve the desired frictional force. The axial normal force can be achieved by a spring, wherein the weight of the mass / inertia element in the vertical borehole and the spring can be constructed from the housing, etc. The material of the drill bit support assembly can be a steel body or matrix (e.g., a composite material). An axial bearing can be used to decouple the potential normal force spring stack or another normal force applying element from the rotational movement of the inertial mass.

[0139] In some implementations, a tangential damper element may be used within the drill bit housing or other components of the drill bit support assembly. The damper for tangential damping may be mounted relative to the axial axis of the drilling system (e.g., relative to tool axis A). x (Radially) in a position with a high radius.

[0140] For a damper installed to move freely in the tangential direction (direction of tangential acceleration), a threaded connection can be used to a (steel) tube within the drill bit support assembly. The tangential damper can be assembled into the tube, thereby incorporating a mechanism that applies a normal force between the inertial mass (i.e., the damper element) and the support assembly (e.g., the drill bit housing)—preferably orthogonal to the tangential direction. In some embodiments, the tangential damper element can be, for example, threadedly mounted to a corresponding housing or portion thereof within the drill bit housing or other component that can be secured to the drill bit support assembly. The housing can have any geometry that allows it to be mounted in various locations within the drill bit support assembly.

[0141] As described above, according to embodiments of this disclosure, a damper element or assembly is described that, in some configurations, comprises a rotational inertia damper element that can be coupled to the drilling system solely by a damping force or torque on an upper part of the drive shaft. For example, as those skilled in the art will understand and in accordance with the teachings herein, the damping force can be generated, for example, by viscous damping, frictional damping, piezoresistive damping, or (e.g., eddy current type) magnetic damping. In some embodiments, the damper element can be combined with a spring that enables a tuned mass damper or a tuned friction damper. In some such embodiments, the eigenfrequency of the damper providing stiffness (e.g., a spring) and damping, and the eigenfrequency of the adjusted force element, can be tuned to the eigenfrequency of the mode to be damped.

[0142] The drill bit is connected to a support assembly (e.g., a drill bit housing) with damping elements as described above. In some configurations, a different threaded connection may be used between the lower drive shaft and the drill bit support assembly, which allows for the optional incorporation of a friction ring inertial damper. The damping element may be protected by a cap sleeve that is frictionally connected at the upper and lower ends. The cap sleeve does not necessarily provide damping because the normal force ideally prevents sliding movement between the contact surfaces located between the cap sleeve and other components of the drill bit support assembly (e.g., the drill bit housing and tool sleeve). The frictional force is controlled by the coefficient of friction and the normal force caused by the threaded connection between the lower drive shaft and the drill bit support assembly.

[0143] According to some embodiments of this disclosure, the damper element (e.g., an inertial damper) is a ring placed beneath the cover sleeve. The damper element is rotatable freely relative to the drilling system, drill bit support assembly, or other structures. In some embodiments, the mass of the damper element may be provided by a non-magnetic material to prevent interaction with and / or interference with measurements from a magnetometer, which may be positioned close to the drill bit and / or drill bit support assembly. Similarly, the material of the damper element may be selected to minimize or prevent negative impacts on formation assessment measurements or other downhole measurements or operations. As described above, in some embodiments, the damper element may be supported by a frictionless or substantially frictionless radial bearing. The damper element (e.g., an inertial ring) is configured to pass through friction surfaces, such as the contact portion located between the damper element and the drill bit support assembly, or other surfaces (e.g., Figure 23 The friction surface 2326 shown interacts with the drilling system. In some embodiments, the various friction surfaces are axially aligned. The normal force in the friction surfaces is provided by an axial spring (e.g., Figure 23 The axial spring (2324) shown applies friction. The coefficient of friction is based on the material properties of the surfaces interacting with each other frictionally. In some embodiments, the axial spring can be rotatably decoupled from the inertial element via an axial bearing.

[0144] Turn now Figures 24 to 25 A schematic diagram of damper elements 2400 and 2500 is shown. As described above, damper elements 2400 and 2500 are configured for mounting within a drill bit support assembly. Each damper element 2400 and 2500 includes a corresponding housing 2402 and 2502 for receiving and containing the components of the respective damper element 2400 and 2500. The first damper element 2400 has a substantially rectangular geometry (with curved corners), and the second damper element 2500 has a substantially circular geometry. The housings 2402 and 2502 are configured for mounting into the drill bit support assembly (e.g., as shown in the diagram). Figure 23 (As shown).

[0145] Damping elements 2400 and 2500 each include mass elements 2404 and 2504 movably mounted within housings 2402 and 2502, respectively. Mass elements 2404 and 2504 are arranged between mounting elements 2406 and 2506 and contact elements 2408 and 2508. Mounting elements 2406 and 2506 are configured to apply forces on the respective mass elements 2404 and 2504 toward the contact elements 2408 and 2508. Therefore, frictional contact can be achieved between the respective mass elements 2404 and 2504 and the contact elements 2408 and 2508. Mass elements 2404 and 2504 may be arranged within the respective housings 2402 and 2502 together with one or more limiting stops 2410 and 2510. Limiting stops 2410 and 2510 may include optional stiffness or hydraulic elements for damping the movement of mass elements 2404 and 2504.

[0146] Furthermore, the limiting stops 2410 and 2510 prevent the mass elements 2404 and 2504 from getting stuck in one edge of the housings 2402 and 2502. The limiting stops 2410 and 2510 may be configured with springs or other elements to avoid damaging the mass elements 2404 and 2504 and to push the mass elements 2404 and 2504 toward a central or rest position relative to the housings. In some embodiments, it may be advantageous to optimize the spring stiffness and / or clearance in the housings 2402 and 2502 to allow movement of the mass elements 2404 and 2504 within the housings 2402 and 2502. The damper elements 2400 and 2500 may be arranged as inserts (e.g., housings 2402 and 2502 are configured for mounting). Insertable damper elements 2400, 2500 can be mounted such that mass elements 2404, 2504 are placed at a position with a high radius relative to the axis of the drilling system (e.g., the axial axis) to increase the rotational inertia of increased damping relative to that axis.

[0147] Mounting elements 2406 and 2506 are configured to apply a normal force to mass elements 2404 and 2504. For example, mounting elements 2406 and 2506 may be arranged as spring housings to press mass elements 2404 and 2504 into contact with contact elements 2408 and 2508. Furthermore, mounting elements 2406 and 2506 and / or contact elements 2408 and 2508 may be configured to control the tangential movement of mass elements 2404 and 2504 to enable damping of the HFTO. In some embodiments, mounting elements 2406 and 2506 press mass elements 2404 and 2504 into contact with contact elements 2408 and 2508 to generate a frictional force. This frictional force may be applied, for example, by a material favorable to the coefficient of friction and the expected wear, which should be as low as possible.

[0148] According to embodiments of this disclosure, damping can be integrated into the drill bit support assembly. Damping can be applied by any axial, tangential, and / or radial force or a corresponding torque capable of dissipating energy. In the case of coupled modes, the damping force in the axial direction can also dissipate energy in the torsional direction. As described for frictional damping, contact surfaces to which a coefficient of friction and a normal force are applied can be optimized and / or selected to dampen one or more critical modes. In some embodiments, advantageous materials or designs can be employed to prevent wear (e.g., copper or polycrystalline diamond cutters). Multiple contacts with different properties can be used to tune the system to an advantageous coefficient of friction or characteristics. In some embodiments, the damper element is configured to move relative to the drill bit support assembly (e.g., the drill bit housing) at a speed that is the sum of a periodic velocity fluctuation with amplitude and an average speed, wherein the average speed is lower than the amplitude of the periodic velocity fluctuation.

[0149] Depending on the type of force applied, different configurations are possible. As discussed above, Figure 2 Typical force characteristics for frictional contact are described. The force characteristics exhibit a velocity weakening effect for relative velocities that are not close to zero. As discussed above, harmonic or periodic relative movement between two elements will introduce energy into the system. Furthermore, as mentioned above, in this case, damping only approaches zero for relative movement at the interacting surfaces (e.g., ...). Figure 2 It is only effective at point 204. An alternative (or in combination with a friction damper) could be a viscous damper.

[0150] Turn now Figure 26 This illustratively demonstrates different torque (T) / force (F) characteristics of viscous fluids relative to the relative displacement between two parts connected by a connecting force. The graph 2600 represents the properties of a Newtonian fluid (e.g., relative movement / velocity). In this graph, curve 2602 represents the properties of a shear-thinned non-Newtonian fluid, curve 2604 represents the properties of a shear-thinned non-Newtonian fluid, and curve 2606 represents the properties of a shear-thickening non-Newtonian fluid. Although graph 2600 is an example of a fluid, this principle can be applied to other types of dampers, such as non-contact dampers (e.g., eddy current dampers). On graph 2600, curve 2602 includes points 1, 2, and 3; curve 2604 includes points 4, 5, and 6; and curve 2606 includes points 7, 8, and 9. Points 1-9 represent the torque T or force F relative to the relative displacement. The difference in the relationship.

[0151] In graph 2600, the slopes of curves 2602, 2604, and 2606 (e.g., at points 1-9) are positive, and the relative motions (including the average velocity at those points) with respect to these points are also positive. The fluctuations in relative displacement, velocity, or acceleration of the forcibly connected parts caused by periodic superimposed oscillations (e.g., caused by HFTO) will provide damping to the system. Relative movement can occur, for example, between parts connected to the borehole wall, through viscous friction in the tangential direction, as with the presence of a non-rotating sleeve utilizing a steering unit. If a positive average rotational speed is applied, the two interacting bodies forcibly connected by this characteristic will also provide damping to the HFTO. On the downside, this characteristic will also result in average static forces (from the contact surfaces) Figure 26 In the T and F (corresponding to points 1-9), the average static reduction comes from the power available for rotation that can be used to break the rock. That is, the damper acts as a brake on the rotation of the downhole system. Therefore, in such cases, higher power may be required at the surface rotation system, which drives the cutting action at the drill bit.

[0152] The required damping depends linearly on the slope of the relative displacement curve for different torques, which can be obtained from... Figure 26 The coefficient is named the viscous damping coefficient d(d1-d9), and it varies with the mass-normalized mode amplitude (e.g., as shown in Figure 1). Figure 9B The static energy dissipation from constant relative movement also increases linearly with the viscous damping coefficient d. Because the modal amplitudes are highly localized and very high at the drill bit, and therefore the relative movement between the two forcibly connected surfaces is high as described above, the static energy dissipation is also high and the damping is effective. Due to the localization and high modal amplitudes, the length of the damper can be relatively short (e.g., axial). The braking force of a relatively short damper is less than that of a relatively long damper. Therefore, the trade-off between dynamically provided damping (e.g., to mitigate HFTO) and (undesirable) static energy dissipation is particularly good near the drill bit or drill bit support assembly.

[0153] Turn now Figure 27 A drill bit support assembly 2700 is shown, having a damper element 2701 in the form of a viscous damper or an eddy current damper. The drill bit support assembly 2700 may be similar to the drill bit support assemblies shown and described above, having a drill bit housing 2702 attached to a drive shaft 2706, wherein the drill bit housing 2702 is configured with a drill bit cavity 2704 to receive a drill bit or other fracturing equipment. The drive shaft 2706 and torque sleeve 2708 may be housed within a tool sleeve 2718. The tool sleeve 2718 may be a non-rotating sleeve or a slowly rotating sleeve, as those skilled in the art will understand. The tool sleeve 2718 may be configured to engage or connect to a BHA or other downhole components and / or tool strings (such as steering units). In this embodiment, as shown, the tool sleeve 2718 may engage with a borehole wall 2750 using force-applying members 2752 (such as one or more ribs, extensions, etc.), as those skilled in the art will understand. The tool sleeve may include, for example, three force-applying members. As is known in the art, the component may also incorporate a type of non-rotating stabilizer.

[0154] The torque sleeve 2708 and drive shaft 2706 rotate to drive the drill bit box 2702, and thus the drill bit or fracturing equipment mounted in the drill bit box. However, the tool sleeve 2718 can be forcibly connected to the borehole wall 2750 using a force-applying member 2752. In some non-limiting embodiments, the force-applying member 2752 can be a steering device that applies force to change the direction of drilling operations. Therefore, the tool sleeve 2718 has an average rotational speed of almost zero. Furthermore, because a bearing or any other decoupling device is used between the torque sleeve 2708 and the tool sleeve 2718, the force-applying member 2752 is decoupled from the dynamic content of HFTO excited by the fracturing equipment.

[0155] The torque sleeve 2708 is subjected to loads from the HFTO, which are harmonic or periodic displacements, velocities or accelerations, and dynamic torsional torques. Therefore, the dynamic relative movement through the HFTO is superimposed on the average relative movement between the torque sleeve 2708 and the tool sleeve 2718. This dynamic relative movement can be used to dampen the HFTO within the drill bit support assembly 2700. The damping force is provided by the damper element 2701 and can be adjusted circumferentially or only at specific portions of the diameter, and by having a relative... Figure 26 Damping force devices with characteristics similar to those described are forcibly connected to torque sleeve 2708 and tool sleeve 2718. That is, in Figure 26At operating points 1-9, a positive slope is required relative to the relative velocity (x-axis) and the transmitted force or torque. This behavior is not limited to hydraulic damping but can be achieved by any other damping force or a combination of damping forces as described herein. That is, damper element 2701 can be a viscous damper or a hydraulic damper, but is not limited to these. For example, an eddy current damper can be used, which exhibits a Newtonian fluid-like relationship between torque and relative velocity. Figure 26 The curve 2602 shown has a purely linear slope. In this context, if the relative movement has a dynamic content from the oscillation connected to the HFTO, the system can be damped by using two parts that are forcibly connected, with or without an average relative velocity close to zero or non-zero. In this example, one of the two forcibly connected parts has zero dynamic content because the dynamic movement of that part from the drill bit support assembly, drive shaft, or similar part that transmits torque is decoupled. Some of the energy from the oscillation can be transferred to the tool sleeve 2718 by the damping force at the damper element 2701. Therefore, it may be advantageous, for example, to design the tool sleeve 2718 or other components / parts (e.g., tool string, downhole string, drilling system, BHA, etc.) to not vibrate excessively due to the mechanism by having a first natural frequency that is different from or higher than the natural frequency of the HFTO of the bottom hole assembly or drilling system.

[0156] Therefore, one form of damping that can be employed in embodiments of this disclosure is hydraulic damping. This hydraulic damping can be achieved by a system located in or around the drill bit support assembly, or in other locations within these locations. In some such embodiments, a viscous fluid (e.g., a viscous fluid in a chamber) can be arranged and installed in locations similar to those described above. In some such applications, the (shear) stress in the fluid between the inertial ring / mass and the drill bit support assembly can be selected to achieve a (damping) force tangential to the tangential acceleration and associated harmonic shift, thereby damping the HFTO. In the case of ring shear, the fluid provides a damping force between the inertial ring and the drill bit support assembly (e.g., the drill bit box). In this case, the ring may require a well-defined geometry of a closed housing and a potential gap between the ring and the housing, which can also be achieved by a cover sleeve. In hydraulic damping, the viscous damping force is sensitive to changes in the parameters of the gap and the viscous fluid. Therefore, a fluid that is insensitive to temperature is preferred. Fluids with varying shear stresses that change with the shear rate can be used to achieve advantageous behavior. Some of these exemplary fluids include, but are not limited to, Newtonian fluids, non-Newtonian fluids (e.g., diluents, shear-thickening fluids, shear-thinning fluids, etc.), pseudoplastics, Bingham plastics, Bingham pseudoplastic fluids, etc.

[0157] Furthermore, in some implementations, magnetic damping may be employed. Magnetic damping can be achieved using a permanent magnet (e.g., mounted on an inertial ring or mass element) that allows movement relative to the coil and can be used to dampen the HFTO. According to magnetic principles, the damping force characteristics are similar to hydraulic (e.g., eddy current) or frictional (hysteresis) forces. In some such configurations, the force will act in the direction of tangential acceleration or in any other direction capable of causing damping in the torsional direction or the direction to be damped.

[0158] Furthermore, in some implementations, the piezoelectric damping principle can be employed to prevent HFTO at the drill bit. A piezoelectric material can be used, connected on one side to an inertial loop or tangential mass and on the other side to a drill bit support assembly. The electrodes of the piezoelectric material can be connected to a circuit incorporating coils, resistors, and capacitors or semi-active or active electronic components. This combination of electrical components can be used to achieve favorable damping characteristics between the inertial loop and the drill bit support assembly. The circuit can be tuned to the system's natural frequency to act as a damper for the tuned mass (i.e., for one or more desired modes). If the piezoelectric stack deforms due to the relative force between the mass element and the drill bit support assembly, the resistor can be arranged to directly dissipate energy. Additionally, the stiffness of the piezoelectric material and the inertial loop mass can also be tuned to a specific frequency. The electrodes of the piezoelectric material can be arranged to dampen torsional vibrations. The direction of the damping force can differ from the direction of the electrodes using a favorable conversion effect from mechanical force to electrical signal proposed by the design of the piezoelectric actuator. The well-known piezoelectric coefficient effect is D... 33 (Electrode in the direction of force), D 31 (orthogonal to the direction of the force) and D 15 (Shear stress). Piezoelectric materials can be positioned to optimize or control the connection between mechanical and electrical systems for specific modes or multiple mode shapes that are critical to HFTO. Furthermore, various different materials can be used to transmit mechanical forces or stresses or associated loads to electrical signals without departing from the scope of this disclosure.

[0159] Furthermore, internal damping and the forces of the resulting material can be used to reduce HFTO. That is, material damping can be passively achieved through the damping properties of highly damped materials. Some such materials include, but are not limited to, polymers, elastomers, rubbers, and multifunctional materials such as shape memory alloys. The material properties of some materials (such as shape memory alloys) can be actively influenced or controlled to achieve a greater damping effect.

[0160] Other damping configurations are possible without departing from the scope of this disclosure. For example, negative capacitors and semi-active components using switching techniques may be employed. Additional damping techniques and components may be used, and the above embodiments and variations are provided for illustrative and explanatory purposes and are not intended to be limiting. All damping principles described herein can be adjusted to act as tuned mass dampers by adding mechanical springs tuned to a specific frequency and by adding any type of damping. Furthermore, one or more damping principles (or other methods / mechanisms) described herein can be combined in a multi-principle configuration. For example, a toroidal inertial damper may be combined with a tangential mass inertial damper mounted within or attached to the blades of a fracturing device. Additionally, magnetic damping forces, hydraulic damping forces, frictional damping forces, piezoresistive damping forces, and material damping forces and principles may be combined to achieve robust damping effects, such as, for example, with respect to temperature.

[0161] As described above, one or more damper elements can be integrated into the drill bit housing or other parts of the drill bit support assembly. For example, a ring-shaped damper can be positioned within or around the drill bit support assembly, as shown and described. In some configurations, the damper inertia ring can be lubricated by mud or covered by a sleeve design. In some configurations, a closed or uninterrupted ring can be used. In other configurations, a partial arcuate element can be assembled around the drill bit support assembly (e.g., it can be installed where the ring cannot be assembled in any other way). In some such embodiments, two half-ring arcuate elements can be used. In other embodiments, depending on the specific configuration implemented, more than two ring arcuate elements can be used to form a complete hoop (circumference) structure or a structure smaller than a complete hoop (circumference).

[0162] In some implementations, a broken-ring structure may be used, where discrete masses are arranged around a portion of the drill bit support assembly. In another example, a complete-ring structure may be arranged around the drill bit support assembly, but specific additional mass elements or features of the ring may be positioned relative to specific parts of the drill bit mounted to the drill bit support assembly (e.g., the cutting edge of the drill bit mounted in the drill bit housing). One such example may have a relatively thick ring and a lower overall thickness at a position relative to the cutting edge of the drill bit mounted in the drill bit housing to allow chip flow to pass along the drill bit support assembly.

[0163] In some embodiments, a limiting stop may be provided for the ring-shaped damper element and to prevent the ring from moving freely around the circumference of the drill bit support assembly. Such limiting stops may be provided in embodiments where the mass or added mass is located behind or adjacent to the specific cutting elements of the drill bit mounted to the drill bit housing. In such cases, the limiting stop ensures that the mass or added mass is held in a fixed position relative to the cutting elements.

[0164] It should be understood that the friction damper element of this disclosure can employ radial and / or axial frictional forces. Radial frictional forces can be achieved through a spring or through an elastic design of an inertia ring with two half-shells, and are prestressed. Axial normal forces can be achieved through a spring, and the mass / weight of the inertia element in the vertical bore and / or the spring can be constructed from the housing, etc. The drill bit support assembly can be made of steel or a matrix composite or other suitable material. In some embodiments, bearings can be used in the radial direction to ensure movement of the inertia ring. That is, bearings can be provided to ensure circumferential and / or tangential movement of the damper element. Axial bearings can be used to decouple the potential normal force spring stack from rotational movement.

[0165] In some embodiments, alternatively, the tangential damper element, either from or in combination with a ring-shaped damper element, may be implemented in or on other parts of the drill bit support assembly. In some such embodiments, the tangential damper element may be mounted within a housing threaded into the drill bit support assembly (e.g., in the drill bit housing). In some such configurations, one or more limiting stops may be provided to prevent the tangential damper from sticking or wedging into the edges or corners of the housing. Contact between the limiting stops and the mass of the tangential damper may be achieved using springs or other biasing elements or structures. In some embodiments, the spring stiffness or clearance in the housing may be selected to allow the mass of the tangential damper to move within the housing, and thus enable damping of vibrations, as described above.

[0166] Adjustable elements can also be used to alter the nature of the contact between contact elements in the drill bit support assembly. For example, the normal force can be adjusted in frictional contact. The nature of the damping can be changed by increasing or decreasing the gap between two interacting surfaces that provide damping through relative movement. For example, in the case of magnetic damping, the amount of damping depends, for example, on... Figure 27 The dimensions of the gap at damper element 2701 are shown. All parameters affecting damping can be adjusted, and are not limited to temperature, geometry, and / or electric field. Furthermore, the efficiency of the damping device can be measured by load and acceleration or other vibration measurement sensing devices and provided to a feedback loop to allow further adjustment of the damping parameters as needed.

[0167] Therefore, embodiments of this disclosure relate to positioning a damping system, such as a ring damper or a tangential damper, at or within the drill bit support assembly of a downhole system. By positioning the damping system at or within the drill bit support assembly, improved damping of HFTO or other vibration modes can be achieved.

[0168] Implementation Scheme 1: A system for damping torsional oscillations in a downhole system, the system comprising: a downhole tubing string; a drill bit support assembly configured to support and receive a fracturing device, wherein the fracturing device is disposed at an end of the downhole tubing string and mounted to the drill bit support assembly; and a damping system configured at at least one of the following: on and / or in the drill bit support assembly, the damping system comprising at least one damper element arranged to contact a portion of the drill bit support assembly.

[0169] Implementation Scheme 2: The system according to any of the foregoing embodiments, wherein the damper element is configured to move at least partially relative to the drill bit support assembly at a certain speed, which is the sum of periodic speed fluctuations with amplitude and average speed.

[0170] Implementation Scheme 3: The system according to any of the foregoing implementation schemes, wherein the fracturing device is a drill bit that engages with the drill bit box of the drill bit support assembly.

[0171] Implementation Scheme 4: The system according to any of the foregoing embodiments, wherein the drill bit support assembly includes: a drive shaft; and a torque sleeve, wherein the drill bit housing is rotatably engaged with the drive shaft, and the torque sleeve is arranged to operatively contact the drive shaft.

[0172] Implementation Scheme 5: The system according to any of the foregoing embodiments, wherein the drill bit box is threadedly connected to the drive shaft.

[0173] Implementation Scheme 6: The system according to any of the foregoing embodiments further includes: a tool sleeve disposed outside the torque sleeve, wherein the at least one damper element is disposed between the torque sleeve and the tool sleeve.

[0174] Implementation Scheme 7: The system according to any of the foregoing implementation schemes, wherein the at least one damper element is mounted to the drill bit support assembly.

[0175] Implementation Scheme 8: The system according to any of the foregoing implementation schemes, wherein the at least one damper element is a ring structure arranged circumferentially around the drill bit support assembly.

[0176] Implementation Scheme 9: The system according to any of the foregoing implementation schemes, wherein the annular structure includes two semi-shells arranged around the drill bit support assembly.

[0177] Implementation Scheme 10: The system according to any of the foregoing embodiments further includes: a cover sleeve disposed outside the at least one damper element such that the at least one damper element is positioned between the cover sleeve and the drill bit support assembly.

[0178] Implementation Scheme 11: The system according to any of the foregoing embodiments further includes: at least one bearing arranged to rotatably decouple the movement of at least a portion of the at least one damper element from the movement of the drill bit support assembly.

[0179] Implementation Scheme 12: The system according to any of the foregoing embodiments, wherein the at least one bearing comprises at least one of a radial bearing and an axial bearing.

[0180] Implementation Scheme 13: The system according to any of the foregoing embodiments further includes: an axial spring configured to press at least a portion of the at least one damper element into frictional engagement with the drill bit support assembly.

[0181] Implementation Scheme 14: The system according to any of the foregoing embodiments, wherein the at least one damper element is a tangential damper element.

[0182] Implementation Scheme 15: The system according to any of the foregoing implementation schemes, wherein the drill bit support assembly includes a steering unit.

[0183] Implementation Scheme 16: The system according to any of the foregoing embodiments, wherein the at least one damper element further includes a limiting stop arranged to prevent at least a portion of the at least one damper element from rotating about the drill bit support assembly.

[0184] Implementation Scheme 17: The system according to any of the foregoing embodiments, wherein the damping system is arranged to provide at least one of viscous damping, frictional damping, hydraulic damping, piezoresistive damping, eddy current damping and magnetic damping at the drill bit support assembly.

[0185] Implementation Scheme 18: The system according to any of the foregoing implementation schemes, wherein the downhole string is a drill string, and the drill bit support assembly is mounted to the end of the drill string.

[0186] Implementation Scheme 19: A method for damping torsional oscillations in a downhole system in a borehole, the method comprising: installing a damping system at at least one of: on and / or in a drill bit support assembly on a downhole string of the downhole system, the drill bit support assembly having a fracturing device attached to the drill bit support assembly, the damping system comprising: at least one damper element arranged to contact a portion of the drill bit support assembly, wherein at least a portion of the damper element moves relative to the drill bit support assembly at a speed that is the sum of a periodic velocity fluctuation having amplitude and an average velocity.

[0187] Implementation Scheme 20: The method according to any of the preceding embodiments, wherein the at least one damper element includes a ring structure mounted around the drill bit support assembly.

[0188] To support the teachings herein, various analytical components, including digital and / or analog systems, may be used. For example, controllers, computer processing systems, and / or geological guidance systems as provided herein and / or used with the embodiments described herein may include digital and / or analog systems. These systems may have components such as processors, storage media, memories, inputs, outputs, communication links (e.g., wired, wireless, optical, or others), 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 manners well known in the art. It may be understood that these teachings may be implemented, but not necessarily, 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 disk drive), or any other type of media, which, when executed, cause a computer to perform 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 system designers, owners, users, or other such persons deem relevant. Processed data (such as the results of implemented methods) may be transmitted as signals via the processor output interface to a signal receiving device. The signal receiving device may be a display monitor or printer used to present the results to the user. Alternatively or otherwise, the signal receiving device may be a memory or storage medium. It should be understood that storing the results in memory or storage medium allows the memory or storage medium to be converted from a previous state (i.e., without results) to a new state (i.e., containing results). Furthermore, in some embodiments, if the results exceed a threshold, an alarm signal may be emitted from the processor to the user interface.

[0189] In addition, various other components may be included, and they may be required to provide 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 the aspects discussed herein or to support other functions beyond this disclosure.

[0190] In the context of describing the invention (particularly in the context of the appended claims), the terms “an,” “a,” and “the,” and similar designations, should be interpreted to cover both the singular and plural, unless otherwise specified herein or clearly contradicted by the context. Furthermore, it should be noted that the terms “first,” “second,” etc., used herein do not indicate any order, quantity, or importance, but are used to distinguish one element from another. The modifier “about,” used in conjunction with quantity, includes the stated value and has a meaning determined by the context (e.g., it includes the degree of error associated with a particular quantity of measurement).

[0191] It should be recognized that various components or technologies may provide certain necessary or beneficial functions or features. Therefore, these functions and features that may be required to support the appended claims and their variations are considered to be inherently included as part of the teachings herein and as part of this disclosure.

[0192] The teachings of this disclosure can be applied to a variety of well operations. These operations may involve treating a formation, fluids residing in the formation, boreholes, and / or equipment in the borehole, such as production tubing, with one or more treatment agents. Treatment agents can be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Exemplary treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, corrosion inhibitors, binders, permeability modifiers, drilling mud, emulsifiers, demulsifiers, tracers, flow improvers, etc. Exemplary well operations include, but are not limited to, hydraulic fracturing, production enhancement, tracer injection, cleaning, acidizing, steam injection, water injection, cementing, etc.

[0193] While the embodiments described herein have been described with reference to various implementations, it should be understood that various changes may be made and equivalents may be substituted for elements therein without departing from the scope of this disclosure. Furthermore, many modifications will be made to adapt particular apparatus, situations, or materials to the teachings of this disclosure without departing from the scope of this disclosure. Therefore, it is contemplated that this disclosure is not limited to the specific embodiments disclosed as the best mode contemplated for achieving the described features, but rather that this disclosure will include all embodiments falling within the scope of the appended claims.

[0194] Therefore, the embodiments disclosed herein should not be considered as limited by the foregoing description, but only by the scope of the appended claims.

Claims

1. A system for damping torsional oscillations in a downhole system, the system comprising: Downhole tubing; A drill bit support assembly configured to support and receive a fracturing device, wherein the fracturing device is disposed on an end of the downhole tubing and mounted to the drill bit support assembly; as well as A damping system, the damping system being configured at at least one of the following: on and / or in the drill bit support assembly, the damping system comprising at least one damper element arranged to contact a portion of the drill bit support assembly; The damper element is configured to move at least partially relative to the drill bit support assembly at a speed that is the sum of periodic velocity fluctuations with amplitude and an average velocity.

2. The system of claim 1, wherein the fracturing device is a drill bit that engages with the drill bit housing of the drill bit support assembly.

3. The system of claim 2, wherein the drill bit support assembly comprises: Drive shaft; as well as A torque sleeve, wherein the drill bit housing is rotatably engaged with the drive shaft, and the torque sleeve is arranged to be operatively in contact with the drive shaft.

4. The system according to claim 3, wherein, The drill bit box is threadedly connected to the drive shaft.

5. The system according to claim 3, wherein, The system also includes a tool sleeve disposed outside the torque sleeve, wherein at least one damper element is disposed between the torque sleeve and the tool sleeve.

6. The system of claim 1, wherein the at least one damper element is mounted to the drill bit support assembly.

7. The system of claim 1, wherein the at least one damper element is a ring structure arranged circumferentially around the drill bit support assembly.

8. The system of claim 7, wherein the annular structure comprises two semi-shells arranged around the drill bit support assembly.

9. The system according to claim 1, further comprising: A cover sleeve is disposed outside the at least one damper element such that the at least one damper element is positioned between the cover sleeve and the drill bit support assembly.

10. The system of claim 1, further comprising at least one bearing disposed in the drill bit support assembly, the at least one bearing being arranged to rotatably decouple movement of at least a portion of the at least one damper element from movement of the drill bit support assembly, wherein, The at least one damper element is in substantially frictionless contact with the at least one bearing.

11. The system of claim 10, wherein the at least one bearing comprises at least one of a radial bearing and an axial bearing.

12. The system according to claim 1, further comprising: An axial spring configured to press at least a portion of the at least one damper element into frictional engagement with the drill bit support assembly.

13. The system of claim 1, wherein the at least one damper element is a tangential damper element.

14. The system of claim 1, wherein the drill bit support assembly includes a steering unit.

15. The system of claim 1, wherein the at least one damper element further comprises a limiting stop arranged to prevent at least a portion of the at least one damper element from rotating about the drill bit support assembly.

16. The system of claim 1, wherein the damping system is arranged to provide at least one of viscous damping, frictional damping, hydraulic damping, piezoresistive damping, eddy current damping, and magnetic damping at the drill bit support assembly.

17. The system of claim 1, wherein the downhole string is a drill string, and wherein the drill bit support assembly is mounted to the end of the drill string.

18. A method for damping torsional oscillations in a downhole system in a borehole, the method comprising: The damping system is installed at at least one of the following: on and / or in a drill bit support assembly on the downhole string of the downhole system, the drill bit support assembly having a fracturing device attached to the drill bit support assembly, the damping system comprising at least one damper element arranged to contact a portion of the drill bit support assembly, wherein the damper element moves at least partially relative to the drill bit support assembly at a speed that is the sum of a periodic velocity fluctuation with amplitude and an average velocity.

19. The method according to claim 18, wherein, The at least one damper element includes a ring structure mounted around the drill bit support assembly.

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