Vibration isolation coupling for reducing vibrations in a drill string

Abstract

A vibration isolation coupling includes a first coupling portion, a second coupling portion including an outer surface and an inner surface portion, and a vibration isolation portion extending between the first coupling portion and the second coupling portion. The vibration isolation portion includes a first solid annular portion and a second solid annular portion. The vibration isolation portion includes a plurality of slots extending from the first solid annular portion toward the second solid annular portion forming a plurality of vibration isolation elements. Each vibration isolation element of the plurality of vibration isolation elements is disconnected from an adjacent vibration isolation element of the plurality of vibration isolation elements by a corresponding slot of the plurality of slots. The plurality of vibration isolation elements enables torsional rotation of the first coupling portion relative to the second coupling portion.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefits of U.S. Provisional Application Serial Nos. 62 / 899,354, 62 / 899,291, 62 / 899,331, and 62 / 899,332, all filed on September 12, 2019, the entire disclosure of which is incorporated herein by reference. Background Technology

[0003] 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.

[0004] 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. Vibration can take the form of viscous / slip vibration and high-frequency torsional oscillation (HFTO). HFTO vibration typically occurs at frequencies above 50 Hz and can be located in a small portion of the drill string. Typically, HFTO has a high amplitude at the drill bit. 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

[0005] This invention discloses a vibration isolation connector for reducing high-frequency torsional oscillations in a drill string. The vibration isolation connector includes: a first connector portion including an outer surface and an inner surface; a second connector portion including both the outer and inner surface portions; and a vibration isolation portion extending between the first and second connector portions. The vibration isolation portion includes a first solid annular portion defining a first terminal and a second solid annular portion defining a second terminal. The vibration isolation portion includes a plurality of slots extending from the first solid annular portion toward the second solid annular portion, thereby forming a plurality of vibration isolation elements. Each of the plurality of vibration isolation elements is disconnected from an adjacent vibration isolation element through a corresponding slot in the plurality of slots. The plurality of vibration isolation elements allows the first connector portion to rotate torsionally relative to the second connector portion.

[0006] A method of isolating high frequency torsional vibrations from a portion of a drill string connected to another portion of the drill string by a vibration isolation coupling having a first coupling portion connected to a second coupling portion by a vibration isolation portion having a plurality of slots defining a plurality of vibration isolation elements. The method includes introducing torsional vibrations into the first coupling portion and isolating the torsional vibrations from the second coupling portion by torsional oscillations of the vibration isolation portion. BRIEF DESCRIPTION OF DRAWINGS

[0007] The following description should not be read as limiting in any way. With reference to the drawings, like elements are numbered alike:

[0008] Figure 1 A resource exploration and recovery system including a vibration isolation coupling is shown according to one aspect of an example embodiment;

[0009] Figure 2A A bottom hole assembly (BHA) geometry without a vibration isolation coupling is shown;

[0010] Figure 2B A high frequency torsional oscillation (HFTO) mode without a vibration isolation coupling is shown;

[0011] Figure 3A A BHA geometry with a vibration isolation coupling is shown according to one example aspect;

[0012] Figure 3B A HFTO mode with a vibration isolation coupling is shown according to one example embodiment;

[0013] Figure 4 A vibration isolation coupling is shown according to one aspect of an example embodiment;

[0014] Figure 5 A cross-sectional view of the vibration isolation coupling of Figure 4 taken along line 3-3 is shown according to one aspect of an example embodiment;

[0015] Figure 6 An isometric view of a portion of the vibration isolation coupling of Figure 4 is shown according to one aspect of an example embodiment;

[0016] Figure 7 An axial end view of a portion of the vibration isolation coupling of Figure 6 is shown according to one aspect of an example embodiment;

[0017] Figure 8An axial end view of a portion of a vibration isolation coupling is shown according to a further aspect of one example embodiment;

[0018] Figure 9 An axial end view of a portion of a vibration isolation coupling is shown according to a further aspect of one example embodiment;

[0019] Figure 10 An axial end view of a portion of a vibration isolation coupling is shown according to a further aspect of one example embodiment;

[0020] Figure 11 A cross-section of a vibration isolation coupling is shown according to a further aspect of one example embodiment;

[0021] Figure 12 An axial end view of a portion of a vibration isolation coupling is shown according to a further aspect of one example embodiment; and

[0022] Figure 13 A cross-section of an end portion of a vibration isolation coupling is shown according to a further aspect of one example embodiment. DETAILED DESCRIPTION

[0023] A detailed description of one or more embodiments of the devices and methods disclosed herein is presented in reference to the drawings.

[0024] Figure 1 A schematic view of a resource detection and recovery system for performing downhole operations is shown. The resource detection and recovery system includes a downhole assembly. As shown, the resource detection and recovery system takes the form of a drilling system 10. The drilling system 10 includes a conventional derrick 11 erected on a floor 12 that supports a rotary table 14 that is rotated at a desired rotational speed by a prime mover, such as an electric motor (not shown). Figure 1 The downhole assembly of the drilling system 10 takes the form of a drill string 20 that extends through the rotary table 14 and includes a drilling tubular 22, such as a drill pipe, into a borehole 26 having an annular wall 27 that extends into a geologic formation 28. The drill string can be a directional drill string that includes a deflection device, a drilling motor, and / or a steering unit 65.

[0025] The fragmentation tool 30, such as a drill bit attached to the end of the drill string 20, forms part of a bottom hole assembly (BHA) 32. The fragmentation tool 30 is operated to fragment the geological formation 28, thereby forming the borehole 26. The drill string 20 is coupled to surface equipment, such as a system for lifting, rotating and / or pushing (including but not limited to) a drawworks 33 through a cathead 43 via a kelly joint 35, a swivel 38 and a line 39. In some embodiments, the surface equipment can include a top drive (not shown). During drilling operations, the drawworks 33 is operated to control the weight on bit, which affects the rate of penetration of the fragmentation tool 30 into the geological formation 28. Operation of the drawworks 33 is well known in the art and is therefore not described in detail herein.

[0026] During drilling operations, a suitable drilling fluid 45 (also referred to as "mud") from a mud pit 48 is circulated by a mud pump 50 under pressure through the interior bore of the drill string 20. The drilling fluid 45 enters the drill string 20 via a desurger 56, a flow line 58 and the kelly joint 35. The drilling fluid 45 exits at the bottom 60 of the borehole 26 through an opening in the fragmentation tool 30. The drilling fluid 45 circulates up the wellbore through an annular space 64 between the drill string 20 and the annular wall 27 (borehole wall) of the borehole 26 and is returned to the mud pit 48 via a flowback line 68. A sensor SI in the flow line 58 provides information about the flow rate of the fluid. A surface torque sensor S2 and a sensor S3 associated with the drill string 20 provide information about the torque and rotational speed, respectively, of the drilling tubular 22. Additionally, one or more sensors (not shown) associated with the line 39 are used to provide hook load data for the drill string 20 as well as other desired parameters related to the drilling of the borehole 26. The drilling system 10 can also include one or more downhole sensors 70 positioned on the drill string 20 and / or the BHA 32.

[0027] In some applications, the fragmentation tool 30 is rotated by rotating the drilling tubular 22. However, in other applications, a drilling motor (not shown), such as a mud motor, can form part of the BHA 32 and can be operated to rotate the fragmentation tool 30 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 fragmentation tool 30 into the geological formation 28 depends largely on the weight on bit and the drill bit rotational speed.

[0028] The surface control unit 80 receives signals from the downhole sensors 70 and equipment via transducers 83, such as pressure transducers, placed in the fluid line 58, and from sensors S1, S2, S3, hook load sensors, RPM sensors, torque sensors, and any other sensors. The surface control unit 80 processes such signals in accordance with programmed instructions. The surface control unit 80 can display on a display / monitor 85 desired drilling parameters and other information used by the operating personnel at the rig site to control the drilling operation. The surface control unit 80 includes a computer, memory for storing data, computer programs, models, and algorithms accessible to the processor in the computer, a recorder, such as a tape unit, memory unit, or the like, for recording data, and other peripherals. The surface control unit 80 can also include simulation models used by the computer to process data in accordance with programmed instructions. The surface control unit 80 can be responsive to user commands entered through suitable devices, such as a keyboard. The surface control unit 80 is adapted to activate an alarm 87 in the event of certain unsafe or undesirable operating conditions.

[0029] The BHA 32 also includes other sensors and devices or tools for providing a variety of measurements related to the geological formation 28 and for drilling the borehole 26 along a desired path. Such devices can include devices for measuring the resistivity of the formation near and / or ahead of the fracturing tool 30, gamma ray devices for measuring the gamma ray intensity of the formation, and devices for determining the inclination, azimuth, and position of the drilling tubular 22. Other devices, such as logging-while-drilling (LWD) devices (indicated generally at 90, such as devices for measuring formation porosity, permeability, density, rock properties, fluid properties, etc.) can be placed at suitable locations in the BHA 32 for providing information useful for evaluating the geological formation 28 of the borehole 26. Such devices can include, but are not limited to, temperature measurement tools, pressure measurement tools, borehole diameter measurement tools (e.g., calipers), acoustic tools, nuclear tools, nuclear magnetic resonance tools, and formation testing and sampling tools. Additional measurement-while-drilling (MWD) tools (not shown) can include directional and dynamic measurement tools for measuring magnetic fields, accelerations, loads, and possibly derived characteristics such as inclination, azimuth, rotational speed, etc.

[0030] The above equipment transmits data to a downhole telemetry system 92, which in turn transmits received data up the wellbore to the surface control unit 80. The downhole telemetry system 92 also receives signals and data from the surface control unit 80 and transmits such received signals and data to the appropriate downhole equipment. In one aspect, a mud pulse telemetry system can be used to communicate data between downhole sensors (indicated generally by 94, disposed on the drill string 20) and equipment and the surface equipment during drilling operations. A transducer 83 placed in a fluid line 58 (e.g., a mud supply line) detects mud pulses in response to data transmitted by the downhole telemetry system 92. The transducer 83 generates electrical signals in response to mud pressure changes and transmits such signals to the surface control unit 80 via a conductor 96.

[0031] In other aspects, any other suitable telemetry system can be used for bidirectional data communication (e.g., downlink and uplink) between the surface and the BHA 32, including but not limited to acoustic telemetry systems, electromagnetic telemetry systems, optical telemetry systems, wired pipe telemetry systems that can utilize wireless couplers or repeaters in the drill string or borehole. A wired pipe telemetry system can be constructed by connecting drill pipe sections, where each pipe section includes a data communication link (such as an electrical wire) extending along the pipe. Data connections between pipe sections 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 direct coupling methods. In the case where coiled tubing is used as the drilling tubular 22, the data communication link can extend along the side of the coiled tubing.

[0032] The drilling system 10 relates to those drilling systems that utilize a drill pipe to deliver the BHA 32 into the borehole 26, where the weight on bit is typically controlled from the surface by controlling the operation of the drawworks 33. However, a large number of current drilling systems, particularly those used to drill highly deviated boreholes and horizontal boreholes, utilize coiled tubing to deliver the drilling assembly downhole. In such applications, a thruster (not separately labeled) can be deployed in the drill string 20 to provide the desired force on the fracturing tool 30. Additionally, when coiled tubing is employed, the tubing is not rotated by a rotary table, but is instead injected into the borehole by a suitable injector, while a downhole motor such as a drilling motor (not shown) rotates the fracturing tool 30. For offshore drilling, an offshore rig or vessel can be used to support the drilling equipment, including the drill string.

[0033] Still referring to Figure 1A resistivity tool 100 can be provided that includes, for example, a plurality of antennas including, for example, a transmitter 104a or 104b or and a receiver 108a or 108b. Resistivity can be one formation property of interest when making drilling decisions. Those skilled in the art will appreciate that other formation property tools can be used with or instead of the resistivity tool 100.

[0034] Liner drilling can be a configuration or operation that is becoming more attractive in the oil and gas industry because of several advantages compared to conventional drilling. One example of such a construction is shown and described in commonly 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,” which is incorporated by reference herein in its entirety. Importantly, although the rate of penetration is relatively low, the time required to position the liner to the target depth is reduced because the liner is being run in while the borehole is being drilled. This can be beneficial in swelling formations where the contraction of the borehole can hinder installation of the liner. In addition, using a liner to drill in a depleted and unstable reservoir can minimize the risk of sticking pipe or drill string due to borehole collapse.

[0035] Although Figure 1 Although shown and described with respect to drilling operations, those skilled in the art will appreciate that similar constructions can be used to perform different downhole operations, although with different components. For example, as known in the art, completion, wireline, wireline pipe, liner drilling, under-reaming, coiled tubing, re-entry, and / or other constructions can be used. In addition, production configurations can be employed for extracting material from and / or injecting material into a formation. Accordingly, the present disclosure is not limited to drilling operations, but can be used for any appropriate or desired downhole operation or operations.

[0036] Severe vibrations in the drill string and bottom hole assembly during drilling operations can be caused by cutting forces at the fragmentation tool 30 or mass imbalances in downhole tools such as drilling motors. Such vibrations can result in reduced rate of penetration, reduced wellbore quality, reduced quality of measurements taken by tools of the bottom hole assembly, and can result in downhole component wear, fatigue, and / or failure. As understood by those skilled in the art, there are different vibrations, such as lateral, axial, and torsional vibrations. For example, stick / slip and high frequency torsional oscillation (“HFTO”) of the entire drilling system are both types of torsional vibrations. The terms “vibration,” “oscillation,” and “fluctuation” are used in the same broad sense of repeated and / or periodic motion or periodic deviation of the mean (such as mean position, mean velocity, and mean acceleration). In particular, 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, harmonic, and statistical deviations.

[0037] Torsional vibrations can be excited by a self-excitation mechanism that occurs due to the interaction of the fragmentation tool 30 or any other cutting structure such as an under-reamer bit with the formation. The main difference between stick / slip and HFTO is the frequency and the typical mode shape: for example, HFTO has a frequency that is typically higher than 50 Hz compared to stick / slip torsional vibrations that usually have a frequency lower than 1 Hz. Typically, HFTO of particular interest can be in the range between 50 Hz and 500 Hz. These HFTO modes are referred to as critical HFTO or critical HFTO modes. Criteria to identify critical HFTO modes are described in Andreas Hohl et al., Journal of Sound and Vibration, 342 (2015), 290-302. Furthermore, the excited mode shape of stick / slip is typically the first mode shape of the entire drilling system, whereas the mode shape of HFTO can be of higher order and is typically localized to a smaller portion of the drilling system and relatively high at the excitation point, which can be the fragmentation tool 30 or any other cutting structure such as an under-reamer bit or any contact between the drilling system and the formation (e.g., realized by stabilizers).

[0038] Due to the high frequency of the vibrations, HFTO corresponds to high acceleration and torque values along or in only a portion of the BHA. Those skilled in the art will appreciate that for torsional motion, one of acceleration, force, and torque always accompanies the other two. In this sense, acceleration, force, and torque are equivalent in the sense that none of these can occur without the other two. The load of high frequency vibrations can have a negative impact on the efficiency, reliability, and / or durability of the electronic and mechanical components of the BHA. Embodiments provided herein are directed to providing a vibration isolation coupler 140 to mitigate HFTO. The vibration isolation coupler 140 is a modular tool that can be installed at various locations above, below, or within the BHA 32.

[0039] For example, the vibration isolation coupler 140 can be installed above the fragmentation tool 30. In a directional drill string (directional BHA), a steering unit 65 can be located above the fragmentation tool 30. In one embodiment, a stabilizer (subsea stabilizer) can be placed above and / or below the vibration isolation coupler 140. The stabilizer located above and / or below the vibration isolation coupler centers the vibration isolation coupler in the borehole and prevents the surface of the vibration isolation coupler from contacting the annular wall 27. The steering unit 65 is located near the fragmentation tool 30 in order to adjust the direction of drilling. In one embodiment, the vibration isolation coupler 140 is disposed in the upward direction along the borehole from the steering unit 65. Above the vibration isolation coupler, there can be one or more formation evaluation (FE) tools.

[0040] The fragmentation tool 30 is the point of excitation of HFTO. Without a vibration isolation coupler in the BHA, HFTO would excite HFTO along the entire BHA above a desired threshold. The vibration isolation coupler 140 isolates the propagation of HFTO excited in the portion of the BHA above the vibration isolation coupler 140 from the portion of the BHA below the vibration isolation coupler. The vibration isolation coupler 140 limits the excitation of HFTO by the cutting forces at the fragmentation tool 30 to the BHA below the vibration isolation coupler 140. Due to the design of the vibration isolation coupler 140, the torsional dynamics of the BHA are modified to allow selected HFTO modal shapes to have a selected amplitude only in the portion of the BHA below the vibration isolation coupler 140. The vibration isolation coupler 140 in the BHA allows the portion of the BHA below the vibration isolation coupler 140 to oscillate (HFTO) by isolating oscillations from the portion of the BHA above the vibration isolation coupler. In addition, the vibration isolation coupler changes the number of HFTO modes excited. In the BHA with the vibration isolation coupler, a smaller number of HFTO modes are excited.

[0041] The vibration isolation coupler 140 acts as a mechanical low pass filter for the HFTO and includes an isolation frequency (natural frequency or first resonant frequency). The isolation effect of the vibration isolation coupler 140 is caused by the significantly smaller isolation frequency of the vibration isolation coupler compared to the HFTO frequencies excited at the fracturing device 30 or at any other cutting structure in the BHA. The smaller isolation frequency can be achieved by using a vibration isolation coupler 140 with a sufficiently small torsional stiffness. The small torsional stiffness of the vibration isolation coupler 140 in the torsional degree of freedom for frequencies above the isolation frequency will isolate the mass located below the vibration isolation coupler 140 from the mass located above the vibration isolation coupler 140. The HFTO modes excited at the fracturing tool 30 at frequencies above the isolation frequency are isolated from the portion of the BHA located above the vibration isolation coupler 140. In one embodiment, a suitable isolation frequency of the vibration isolation coupler in the downhole assembly is between 10 Hz and 100 Hz. Alternatively, in another embodiment, the isolation frequency can be between 10 Hz and 70 Hz. In yet another embodiment, the isolation frequency (first natural frequency or first resonant frequency) can be between 20 Hz and 50 Hz. Simulations show that an isolation frequency of 30 Hz achieves the desired isolation of the HFTO modes. The isolation frequency of the vibration isolation coupler 140 depends on the torsional spring constant (or torsional stiffness) of the vibration isolation coupler 140 and the oscillating mass below the vibration isolation coupler 140. The term "small torsional stiffness" refers to a ratio between the bending stiffness and the torsional stiffness (Bending Stiffness / Torsional Stiffness (BST / TST)) greater than 10, greater than 15, greater than 20, greater than 30, greater than 40, or greater than 50.

[0042] In one embodiment, positioning the vibration isolation coupler 140 above the steering unit 65 and the drilling fracturing tool 303 provides a sufficiently high oscillating mass that achieves an isolation frequency of about 30 Hz. A smaller mass (e.g., only the fracturing tool 30) results in an isolation frequency higher than 30 Hz, such as a frequency between about 150 Hz and about 200 Hz. The BHA assembly located near the fracturing tool 30 is designed to withstand high levels of vibration (axial, lateral, and torsional). An isolation frequency of 30 Hz limits the HFTO modes, the associated torque loads, and the angular acceleration loads acting on the steering unit 65 and the fracturing tool 30 to only a few selected HFTO modes. A higher isolation frequency would result in more HFTO modes excited in the portion of the BHA located below the vibration isolation coupler 140, which can result in damaging the steering unit 65 and / or the fracturing tool 30. In this embodiment, the lower portion of the BHA (located below the vibration isolation coupler 140) is decoupled (isolated) from the upper portion of the BHA (located above the vibration isolation coupler).

[0043] In an alternative embodiment, it is possible to excite HFTO modes with the BHA located in a portion of the vibration isolation coupler (e.g. by a washover drill). In such examples, the vibration isolation coupler 140 isolates the portion of the BHA below the vibration isolation coupler from the HFTO modes. In a BHA with a vibration isolation coupler as described herein, the HFTO mode shape amplitude above the vibration isolation coupler 140 (the portion of the BHA without HFTO excitation) is relatively low compared to the HFTO mode shape amplitude below the vibration isolation coupler 140 (the portion of the BHA with HFTO excitation).

[0044] Figure 2A and Figure 2B The geometry of a reference BHA (4.75” tool size) in a drill string without a vibration isolation coupler is shown, along with simulated six HFTO mode shapes with corresponding frequencies (f) between 119.4 Hz and 357.6 Hz. The parameter S c is an indicator of the likelihood of occurrence of a HFTO mode shape. The HFTO mode shape amplitude indicates the location of the torsional vibration energy in the BHA section of the drill string.

[0045] Figure 3A and Figure 3B The geometry of a reference BHA in a drill string with a vibration isolation coupler 140 placed above the fracturing tool 30 and the steering unit 65 is shown. The addition of the vibration isolation coupler 140 results in a lower number of HFTO modes in the frequency range of 50 Hz to 500 Hz. There are also other modes of the vibration isolation coupler with high likelihood of occurrence at or near the isolation frequency of the vibration isolation coupler (30 Hz). However, these HFTO modes with small frequency / small amplitude do not have an impact similar to the HFTO modes with higher frequency / amplitude that occur along the BHA in the reference BHA without a vibration isolation coupler Figure 2A and Figure 2B ).

[0046] Figure 2A , 2B and Figure 3A , 3B The simulated results shown demonstrate that the HFTO is concentrated at the fracturing tool 30 and the steering unit 65. Above the vibration isolation coupler 140, the HFTO mode shape amplitude is significantly reduced in magnitude compared to the corresponding mode shape amplitude below the vibration isolation coupler 140. In the upper portion of the reference BHA without a vibration isolation coupler 140 Figure 2A , 2BThe HFTO mode shapes present in the FE tool 100 due to varying torsional dynamics are not excited in the BHA with the vibration isolation coupler 140, or appear with significantly smaller HFTO mode shape amplitudes. As a result, the FE tool or MWD tool including highly complex electronics (PCBA, ceramic material including multi-chip modules (MCM)), sensors, connectors, wires, hydraulic devices, and / or mechanical devices located above the vibration isolation coupler 140 are exposed to reduced torsional dynamic loads, resulting in higher quality downhole measurement data (especially imaging data) and enhanced downhole tool reliability.

[0047] In one embodiment, the vibration isolation coupler 140 is formed with a length as short as possible in order to keep the FE tool close to the fracturing tool 30. In one embodiment, the vibration isolation coupler 140 as described herein can be shorter than 2 m. In another embodiment, the vibration isolation coupler 140 can be shorter than 1.5 m. In yet another embodiment, the vibration isolation coupler 140 can be shorter than 1.2 m. In yet another embodiment, the vibration isolation coupler 140 can be shorter than 1.1 m. In yet another embodiment, the vibration isolation coupler 140 can be shorter than 1 m. In order to achieve the isolation properties, the vibration isolation coupler 140 comprises a small rotational stiffness (torsional softness, small torsional stiffness) to isolate the HFTO. At the same time, the vibration isolation coupler 140 has a high bending stiffness to facilitate the steering behavior of the directional BHA (i.e., the steering unit).

[0048] Different designs for the vibration isolation coupler 140 are presented herein in various embodiments, achieving mechanical properties that balance between torsional softness and bending stiffness while keeping mechanical stresses below acceptable limits. Mechanical stresses are induced by axial loads (weight on bit (WOB)), torque applied by surface equipment (drill string rotation), dynamic bending and vibrations (lateral, axial, torsional) of the borehole turn. The vibration isolation coupler 140 can be formed integrally as only one piece, or can be formed from multiple connected components.

[0049] Vibration isolation couplings that are integrally formed without connections, such as threaded, welded, or otherwise formed connections, are less prone to tool failure. Modern manufacturing methods, such as additive manufacturing, have the opportunity to result in vibration isolation couplings that are formed as an integral part having complex shapes. The vibration isolation couplings as described herein do not include bearings or other components that move relative to one another. The absence of bearings results in reduced wear. The vibration isolation couplings as described herein do not use frictional surfaces or frictional forces to dissipate rotational energy. In this context, friction includes viscous friction (viscous forces). It should be understood that the vibration isolation couplings 140 only isolate rotation associated with torsional oscillations. Rotation (non-oscillatory or continuous rotation) applied by the rotary table or top drive is transmitted from the BHA above the vibration isolation couplings to the BHA below the vibration isolation couplings. Although the vibration isolation couplings 140 isolate the HFTO, the BHAs above and below the vibration isolation couplings are rotatably coupled.

[0050] Referring to Figures 4 to 7 The vibration isolation couplings 140 include a first coupling portion 146 defining a first terminal end 147 and a second coupling portion 148 defining a second terminal end 149, the first and second coupling portions connected by a vibration isolation portion 150. The vibration isolation portion 150 includes a first terminal end 151 and a second terminal end 152. The first coupling portion 146 includes an outer surface and an inner surface (not separately labeled) defining a central passage 141. The second coupling portion 148 includes an outer surface and an inner surface (not separately labeled) defining a central passage 142. The first and second coupling portions 146, 148 include connection elements (not separately labeled) that can be used to connect to adjacent tools, such as threaded segments (not shown). For example, the first coupling portion 146 can take the form of a female threaded connection, while the second coupling portion 148 can take the form of a pin connection. The vibration isolation couplings 140 extend along a longitudinal axis “L”.

[0051] In an alternative embodiment, the pin connection can be included in the first coupling portion 146 and the female threaded connection can be included in the second coupling portion 148. In one embodiment, the vibration isolation couplings 140 are modular tools that can be integrated into a modular BHA. Thus, the vibration isolation couplings 140 also transfer data communications and power from the portion of the BHA located above the vibration isolation couplings 140 to the portion of the BHA located below, and vice versa, through a power and communication bus, such as a powerline bus system (not shown). The power and communication bus can include an electrical or optical connection that travels from the first coupling portion 146 through the vibration isolation portion 140 to the second coupling portion 148. This connection can be provided by electrical (power, data) or optical (data) conductors or wires (also not shown).

[0052] The first coupling portion 146 and the second coupling portion 148 can include connectors (not shown) that interface with the power and communication bus systems of the downhole components above or below the vibration isolation coupler 140. The connectors included in the first coupling portion 146 and / or the second coupling portion 148 can take the form of ring connectors (not shown), or alternatively, the form of central connectors (also not shown) located in the central passages 141 in the first coupling portion 146 and 142 in the second coupling portion 148 and the inner bore (not individually labeled) of the downhole components. Conductors or wires can pass through the vibration isolation portion 150 via the cavities or passages as described herein. In alternative embodiments, other connector types can also be employed.

[0053] In one embodiment, the first coupling portion 146, the second coupling portion 148, and the vibration isolation portion 150 are integrally formed, for example, using additive manufacturing techniques. In one alternative embodiment, the first coupling portion 146 is connected to the first terminal end 151 of the vibration isolation portion 150 and the second coupling portion 148 is connected to the second terminal end 152 of the vibration isolation portion 150 by welding (e.g., stud welding) or by other means of connection including threads. The vibration isolation portion 150 includes a plurality of vibration isolation elements, one of which is indicated with 156. As shown, each of the vibration isolation elements 156 includes an outer surface 158. Depending on the specific shape, the vibration isolation elements can also include an inner surface 159 that defines a chamber or cavity 186. A central support 170 passes through the vibration isolation coupler 140 and joins the first coupling portion 146 and the second coupling portion 148. The chamber or cavity is located in an annular region that surrounds the central support 170. The central support 170 includes an outer surface portion 172 and can include an inner surface portion 174 that defines a central passage portion 175. Figures 4 to 5

[0054] In one embodiment, the plurality of connecting elements 180 are in a radial direction (R) from the central support 170 to the outer surface 158 of the vibration isolation elements 156. In one embodiment, the connecting elements 180 are in a radial direction (R) from the central support 170 to the inner surface 159 of the vibration isolation elements 156. In one embodiment, the connecting elements 180 are in a radial direction (R) from the central support 170 to the outer surface 158 of the vibration isolation elements 156 and in a radial direction (R) from the central support 170 to the inner surface 159 of the vibration isolation elements 156. Figure 7 ​) extends from an outer surface portion 172 of the central support 170 and is connected with the plurality of vibration isolation elements 156. The term "radial" relates to a direction that is perpendicular to the longitudinal axis L of the vibration isolation coupler 140. The plurality of connection elements 180 are integrally formed with the central support 170 and the corresponding vibration isolation element of the plurality of vibration isolation elements 156. As will be detailed herein, the cavities 186 can be used to convey fluids along the drill string 20 or can be used as a path for conductors (electrical conductors, optical conductors) to run. The connection elements 180, the slots 190, and the vibration isolation elements 156 extend from the first coupler portion 146 to the second coupler portion 148 along more than half the length of the vibration isolation portion 150. The slots 190 terminate at a portion of the vibration isolation portion 150 that includes a closed surface and a solid annular portion. The solid annular portion includes a first solid annular portion 143 and a second solid annular portion 144 located at opposite ends of the vibration isolation portion 150. The first solid annular portion 143 encircles the central passage 141 and the second solid annular portion 144 encircles the central passage 142.

[0055] According to one example embodiment, the vibration isolation portion 150 includes a plurality of slots or cutouts 190 that separate and define the plurality of vibration isolation elements 156. The slots 190 extend between the first coupler portion 146 and the second coupler portion 148. Each slot of the plurality of slots 190 includes a first terminal portion 193 and an opposite second terminal portion 194. The first terminal portion 193 is spaced apart from the first terminal 147 defined by the first coupler portion 146 and the second terminal portion 194 is spaced apart from the second terminal 149 defined by the second coupler portion 148. The first terminal portion 193 is closer to the first coupler portion 146 than the second coupler portion 148 and the second terminal portion 194 is closer to the second coupler portion 148 than the first coupler portion 146. The first terminal portion 193 terminates at the first solid annular portion 143 and the second terminal portion 194 terminates at the second solid annular portion 144.

[0056] The slots or cutouts 190 are generally parallel to the longitudinal axis L of the vibration isolation coupler 140. The vibration isolation elements 156 extend along the length of the vibration isolation portion 150 from the first coupler portion 146 to the second coupler portion 148. The vibration isolation elements 156 extend between adjacent (abutting) slots 190 in a circumferential direction C Figure 7 )(perpendicular to the longitudinal axis L). With this arrangement, it should be understood that the plurality of slots 190 do not extend the entire length of the vibration isolation portion 140. The number of slots can vary.

[0057] The first terminal portion 193 and the second terminal portion 194 of the plurality of slots 190 include transition zones to the solid annular portion of the vibration isolation portion 150. The first terminal portion 193 includes a first transition zone 153 to the first solid annular portion 143, and the second terminal portion 194 includes a second transition zone 154 to the second solid annular portion 144. The first and second transition zones each include a smooth transition to the first and second solid annular portions 143, 144. The smooth transition includes at least one radius. In embodiments, the transition zone can include a three center curve or a basket arch. The plurality of vibration isolation elements 156 include transition zones to the solid annular portion of the vibration isolation portion 150. The transition zones from the plurality of vibration isolation elements 156 to the solid annular portion include a smooth transition that includes at least one radius, a three center curve, or a basket arch. The plurality of connecting elements 180 include transition zones to the central support 170 of the vibration isolation portion 150. The transition zones from the plurality of connecting elements 180 to the central support 170 include a smooth transition that includes at least one radius, a three center curve, or a basket arch.

[0058] According to one example embodiment, a torsional input at the first coupler portion 146 is translated through the vibration isolation portion 150 to the second coupler portion 148. The plurality of slots 190 allow the first coupler portion 146 to torsionally rotate relative to the second coupler portion 148 about a longitudinal axis L of the vibration isolation coupler 140. The plurality of slots 190 allow rotation about the longitudinal axis L through elastic bending or deformation of the plurality of vibration isolation elements 156 and torsion of the central support 170. The bending of the plurality of vibration isolation elements is bending generally perpendicular to the longitudinal axis L of the vibration isolation coupler 140. The plurality of slots reduce the torsional stiffness of the vibration isolation portion 150.

[0059] In one embodiment, the first coupler portion 146 and the second coupler portion 148, the vibration isolation portion 150 (including the central support), the connecting element 180, and the plurality of vibration isolation elements 156 are integrally formed. The torsional rotation of the first coupler portion 146 relative to the second coupler portion 148 and the torsional rotation (oscillation) of the vibration isolation portion 150 about the longitudinal axis L of the vibration isolation coupler isolates the HFTO generated by the fracturing tool 30 below the vibration isolation coupler 140 from the portion of the BHA located above the vibration isolation coupler 140. The fracturing tool 30 is located below the vibration isolation coupler 140 and closer to the second coupler portion 148 than the first coupler portion 146. The torsional oscillation occurs at the excitation HFTO frequency excited at the fracturing tool 30 by the cutting forces. The amplitude of the torsional oscillation (perpendicular to the longitudinal axis L) decreases along the vibration isolation portion 150. In an ideal case, the first coupler portion 146 is no longer oscillating. That is, the HFTO is isolated from the first coupler portion 146 by the vibration isolation portion 150.

[0060] The isolation of the torsional oscillation between the second coupler portion 148 and the first coupler portion 146 is achieved by the torsional softness of the vibration isolation portion 150, which allows the second coupler portion 148 to rotate relative to the first coupler portion 146. In an embodiment, the torsional input occurs at the first coupler portion 146. This can occur when, for example, the HFTO is generated closer to the first coupler portion 146 than the second coupler portion 148 by a reamer located above the vibration isolation coupler 140. In one exemplary embodiment, the fracturing tool 30 is located downhole of the vibration isolation coupler 140. The first coupler portion 146 is located uphole, and the second coupler portion 148 is located downhole. In one exemplary aspect, the first coupler portion 146 represents the more surface-located end of the vibration isolation coupler 140. By using an optimized topology to form the vibration isolation portion 150, the required torsional softness or flexibility of the vibration isolation portion 150 is achieved to achieve the required isolation of the portion of the BHA located above the vibration isolation coupler from the HFTO.

[0061] The torsional stiffness is calculated by the following equation:

[0062] T = G * I T

[0063] where T is the torsional stiffness, G is the shear modulus, and I T is the torsional moment of inertia about the axis of rotation (the longitudinal axis L).

[0064] By using FE modeling, the shape of the central support 170, the connecting element 180, and the vibration isolation elements 156 are adjusted to achieve the torsional moment of inertia I Twhile at the same time (i) maintaining the required bending stiffness and (ii) not exceeding the required axial length of the vibration isolation coupling 140 (typically 1 m). The small torsional inertia moment I T results in a small torsional stiffness T.

[0065] The extension of the vibration isolation element 156 along the longitudinal axis L and the extension of the vibration isolation element in the circumferential direction C of the vibration isolation coupling 140 results in a high bending stiffness.

[0066] In one embodiment, the first coupling portion 146 and the second coupling portion 148 can be formed of the same material as the vibration isolation portion 150. In another embodiment, the first coupling portion 146 and the second coupling portion 148 can be formed of different materials. The slots 190 enable a selected torsional softness by preserving the bending stiffness. The bending stiffness is supported by the orientation of the slots 190 being generally parallel to the longitudinal axis L. These slots are oriented to achieve a rotationally symmetric topology, providing a uniform bending stiffness in each bending direction and avoiding warping deformation effects under torsional movement. The mass distribution of the vibration isolation portion 150 in the circumferential direction is rotationally symmetric by rotation around the longitudinal axis L.

[0067] To achieve uniform bending, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 slots are used. In addition, the shape of the vibration isolation element 156 must satisfy the symmetry requirement to avoid an unbalanced mass in the vibration isolation portion 150 with respect to rotation around the longitudinal axis L and to support its bending stiffness (mainly the circumferential extension of the vibration isolation element 156). The width of the slots is adjusted to allow the vibration isolation portion 150 to have certain torsional angles a Figure 5 ) before the slots close and to prevent further torsion.

[0068] Closing the slots with torsional oscillations results in a locking of the vibration isolation portion 150. The choice of slot width includes a type of end stop in the vibration isolation coupling for a torsional angle a or a torsional oscillation amplitude. The slots extend parallel to the longitudinal axis L along the length of the vibration isolation portion 150 and along at least 50%, 70%, 80%, 90%, 95%, or 99% of the total length of the vibration isolation coupling 140.

[0069] Figure 8A vibration isolation coupling 200 is shown that illustrates another aspect according to one example embodiment. The vibration isolation coupling 200 includes a vibration isolation portion 202 formed by a plurality of vibration isolation elements, one of which is indicated at 204. Each of the plurality of vibration isolation elements 204 includes an outer surface 206 and an inner surface 208. The vibration isolation coupling 200 includes a central support 210 having an outer surface portion 212 and can include an inner surface portion 214 that defines a central passage portion 216.

[0070] In one embodiment, the vibration isolation portion 202 includes a plurality of connecting elements 218 that extend from the outer surface portion 212 of the central support 210 and connect with corresponding ones of the plurality of vibration isolation elements 204. A circumferential extension of the connecting elements 218 (not separately labeled) is less than a circumferential extension of the vibration isolation elements 204 (also not separately labeled), thereby forming a plurality of chambers or cavities in an annular region of the vibration isolation portion 202, one of which is indicated at 220. In one example aspect, the plurality of connecting elements 218 are integrally formed with the central support 210 and corresponding ones of the plurality of vibration isolation elements 204.

[0071] According to one example embodiment, the vibration isolation coupling 200 includes a first plurality of slots or cuts, one of which is indicated at 224, and a second plurality of slots or cuts, one of which is indicated at 226. The first plurality of slots 224 includes a first width, and the second plurality of slots 226 includes a second width that is greater than the first width. It should be appreciated that the first plurality of slots 224 and the second plurality of slots 226 do not extend the entire length of the vibration isolation portion 202.

[0072] According to one example embodiment, a torsional input at a first coupling portion (not shown) of the vibration isolation coupling 200 is translated to a second coupling portion (also not shown). The vibration isolation portion 202 allows the first coupling portion to torsionally rotate relative to the second coupling portion through elastic torsion of the central support 210 and bending or deformation of the plurality of connecting elements 218. In one embodiment, the first coupling portion and the second coupling portion are integrally formed with each of the plurality of vibration isolation elements 204, the connecting elements 218, and the central support 210. The torsional rotation of the first coupling portion relative to the second coupling portion facilitated by the torsional softness of the vibration isolation portion 202 reduces the HFTO generated by the fracturing tool 30.

[0073] Figure 9A vibration isolation coupling 228 is shown that illustrates another aspect according to one example embodiment. The vibration isolation coupling 228 includes a vibration isolation portion 230 having a plurality of vibration isolation elements, one of which is indicated at 231. Each of the plurality of vibration isolation elements 231 includes an outer surface 237 and an inner surface 238. A central support 240 extends through the vibration isolation coupling 228 and includes an outer surface portion 241 and a solid cross-section (not separately labeled). The solid central support positively affects the isolation efficiency of the isolator.

[0074] In one embodiment, a plurality of connecting elements, one of which is shown at 243, extend from the outer surface portion 241 of the central support 240 and connect with corresponding ones of the plurality of vibration isolation elements 231, thereby forming a plurality of annular chambers or cavities 233. In one example aspect, the plurality of connecting elements 243 can be integrally formed with the central support 240 and corresponding ones of the plurality of vibration isolation elements 231. The circumferential extent of the connecting elements 243 (not separately labeled) is less than the circumferential extent of the vibration isolation elements 231, thereby forming the plurality of annular chambers or cavities 233 in the annular region of the vibration isolation portion 228.

[0075] According to one example embodiment, the vibration isolation portion 230 includes a plurality of slots or cutouts 244 that separate and define the plurality of vibration isolation elements 231 and facilitate torsional rotation of the vibration isolation coupling 228 in a manner similar to that described herein. It should be appreciated that the plurality of slots do not extend the entire length of the vibration isolation portion 230.

[0076] In one embodiment, one or more of the plurality of vibration isolation elements 231 can include a passage 252. The passage 252 can extend into a corresponding one of the plurality of connecting elements 243. The number, geometry, and arrangement of the passages 252 can vary. The passages 252 facilitate the flow of fluid through the vibration isolation coupling 228. The passages 252 can also accommodate conductors. The fluid can take the form of drilling mud that flows to the fragmentation tool 30. The drilling mud can flow through a mud motor (not shown) to provide prime mover power to the fragmentation tool 30. The conductors can transfer data, power, and control signals within the BHA from one downhole component to another, such as downhole / subsurface tools, devices, sensors, etc.

[0077] Torsional input at the first coupler portion (not shown) of the vibration isolation coupler 228 is translated to the second coupler portion (also not shown) in a manner similar to that described herein. The plurality of slots 244 allows the first coupler portion to torsionally rotate relative to the second coupler portion through elastic bending or deformation of the plurality of connecting elements 243 and torsion of the central support in a manner similar to that described herein. In one embodiment, the central support 240 is integrally formed with the plurality of vibration isolation elements 231 and connecting elements 243. The torsional rotation of the first coupler portion relative to the second coupler portion facilitated by the torsional softness of the vibration isolation portion 230 reduces HFTO generated by the fragmentation tool 30.

[0078] Figure 10 A vibration isolation coupler 300 according to another aspect of one exemplary embodiment is shown. The vibration isolation coupler 300 includes a vibration isolation portion 304 having a plurality of vibration isolation elements 306. Each of the plurality of vibration isolation elements 306 includes an outer surface 314 and an inner surface 316. A central support 320 extends through the vibration isolation coupler 300. The central support 320 includes an outer surface portion 322 and a solid cross-section (not individually labeled).

[0079] In one embodiment, a plurality of connecting elements, one of which is shown at 324, extend from the outer surface portion 322 of the central support 320 and connect with corresponding ones of the plurality of vibration isolation elements 306, thereby forming a plurality of annular chambers or cavities (not individually labeled). In one exemplary aspect, the plurality of connecting elements 324 are integrally formed with the central support 320 and corresponding ones of the plurality of vibration isolation elements 306.

[0080] According to one exemplary embodiment, the vibration isolation portion 304 includes a plurality of slots or cutouts, one of which is indicated at 328, that facilitate torsional rotation of a first coupler portion (not shown) relative to a second coupler portion (also not shown) in a manner similar to that described herein. It should be appreciated that the plurality of slots do not extend the entire length of the vibration isolation portion 304. It should also be appreciated that the number of slots can vary.

[0081] In one embodiment, one or more of the plurality of connecting elements 324 can include a passage 330 that facilitates the flow of fluid through the vibration isolation coupler 300. The passage 330 can also accommodate a conductor. The fluid can take the form of drilling mud that flows to the fragmentation tool 30. The drilling mud can flow through a mud motor (not shown) to provide prime mover power to the fragmentation tool 30. The conductor can communicate control signals between, for example, the surface control unit 80 and downhole / subterranean tools, devices, sensors, etc.

[0082] Torsional input at the first coupler portion (not shown) of the vibration isolation coupler 300 is translated to the second coupler portion (also not shown) in a manner similar to that described herein. The plurality of slots 328 allows the first coupler portion to torsionally rotate relative to the second coupler portion through elastic bending or deformation of the plurality of connecting elements 324 and torsion of the central support 320. In one embodiment, the central support 320 is integrally formed with the plurality of vibration isolation elements 306 and connecting elements 324. The torsional rotation of the first coupler portion relative to the second coupler portion facilitated by the torsional softness of the vibration isolation portion 304 reduces HFTO generated by the fracturing tool 30.

[0083] Figure 11 A vibration isolation coupler 350 according to another aspect of one example embodiment is shown. The vibration isolation coupler 350 includes a vibration isolation portion 352 having a plurality of vibration isolation elements, one of which is indicated at 354. Each of the plurality of vibration isolation elements 354 includes an outer surface 362 and an inner surface 364. A central support 368 extends through a central bore. The central support 368 includes an outer surface portion 372 and a central passage 374.

[0084] In one embodiment, a plurality of connecting elements, one of which is indicated at 376, extend from the outer surface portion 372 of the central support 368 and connect with corresponding ones of the plurality of vibration isolation elements 354, thereby forming a plurality of annular chambers or cavities (not individually labeled). In one example aspect, the plurality of connecting elements 376 are integrally formed with the central support 368 and corresponding ones of the plurality of vibration isolation elements 354.

[0085] According to one example embodiment, the vibration isolation portion 352 includes a plurality of slots or cuts, one of which is indicated at 390, which facilitate torsional rotation of a first coupler portion (not shown) relative to a second coupler portion (also not shown) in a manner similar to that described herein. It should be appreciated that the plurality of slots 390 do not extend the entire length of the vibration isolation portion 352. It should also be appreciated that the number of slots 390 can vary.

[0086] In one example embodiment, each of the plurality of vibration isolation elements 354 includes a first segment 392 extending outwardly from one of the plurality of connecting elements 376 in a first circumferential direction C( Figure 7 ) and a second segment 394 extending outwardly from the one of the plurality of connecting elements 376 in a second circumferential direction. In one example aspect, the second segment 394 is radially inwardly offset relative to the first segment 392. Radially inwardly refers to the radial direction R( Figure 7). In another exemplary aspect, a first segment 392 extending from one of the plurality of connecting elements 376 overlaps a second segment 394 extending from an adjacent connecting element of the plurality of connecting elements 376. The term "adjacent" in relation to a connecting element, a vibration isolation element, or a slot means abutting connecting elements, vibration isolation elements, or slots.

[0087] In a manner similar to that described herein, a torsional input translation at the first coupler portion (not shown) is translated to the second coupler portion (also not shown). In a manner similar to that described herein, the plurality of slots 390 allows the first coupler portion to torsionally rotate relative to the second coupler portion through elastic bending or deformation of the plurality of connecting elements 376. In one embodiment, the central support 368, each of the plurality of vibration isolation elements 354, and the plurality of connecting elements 376 are integrally formed together. The torsional rotation of the first coupler portion relative to the second coupler portion facilitated by the torsional softness of the vibration isolation portion 352 reduces the HFTO generated by the fracturing tool 30.

[0088] Figure 12 A vibration isolation coupler 400 is shown in accordance with another aspect of one exemplary embodiment. The vibration isolation coupler 400 includes a vibration isolation portion 406 having a plurality of vibration isolation elements 407 separated from one another by a plurality of slots, one of which is indicated with 408. It should be appreciated that the plurality of slots 408 do not extend the entire length of the vibration isolation portion 406. Further, the number of slots 408 can vary. Each of the plurality of vibration isolation elements 407 includes an outer surface 420 and an inner surface 422 defining a cavity (not individually labeled). A central support 409 is disposed in a central bore and includes an outer surface portion 432 and a solid cross-section (not individually labeled).

[0089] In one embodiment, a plurality of connecting elements 440 extend from the outer surface portion 432 of the central support 409 and connect with corresponding ones of the plurality of vibration isolation elements 407, thereby forming a plurality of chambers or cavities 448. In one exemplary aspect, the plurality of connecting elements 440 are integrally formed with the corresponding isolation vibration elements of the plurality of vibration isolation elements 407 and the central support 409.

[0090] In one exemplary embodiment, a conduit 460 extends through one or more of the plurality of cavities 448. The conduit 460 can facilitate the passage of fluid or conductors through the vibration isolation coupler 400. The fluid can take the form of drilling mud that flows to the fracturing tool 30. The drilling mud can flow through a mud motor (not shown) to provide prime mover power to the fracturing tool 30. The conductors can communicate control signals between, for example, the surface control unit 80 and downhole / subterranean tools, devices, sensors, etc.

[0091] In a manner similar to that described herein, a torsional input imparted at a first coupler (not shown) of the vibration isolation coupler 400 is translated to a second coupler (also not individually labeled). The plurality of slots 408 allow the first coupler portion to torsionally rotate relative to the second coupler portion through elastic bending or deformation of the plurality of connecting elements 440 and torsion of the central support 409. In one embodiment, the plurality of vibration isolation elements 407, the central support 409, and the plurality of connecting elements 440 are integrally formed. The torsional rotation of the first coupler portion relative to the second coupler portion facilitated by the torsional softness of the vibration isolation portion 406 reduces the HFTO generated by the fracturing tool 30.

[0092] Reference will now be made to Figure 13 A vibration isolation coupler 500 according to another aspect of one exemplary embodiment will now be described. The vibration isolation coupler 500 includes a first coupler portion 504 that extends to a second coupler portion (not shown) through a vibration isolation portion 510. The vibration isolation portion 510 includes a plurality of vibration isolation elements (one of which is indicated with 520) separated from one another by a plurality of slots (one of which is indicated with 525). It should be appreciated that the plurality of slots 525 do not extend the entire length of the vibration isolation portion 510. Further, the number of slots 525 can vary. The first coupler portion 504 and the second coupler portion (not shown) do not include slots. The portions of the first coupler portion and the second coupler portion that do not include slots include a closed outer surface and can include a solid annular portion that encircles a central passage within the first coupler portion and the second coupler portion. The first coupler portion 504 and the second coupler portion (not shown) each include a passage for conveying a fluid.

[0093] Each of the plurality of vibration isolation elements 520 includes an outer surface 530 and an inner surface 532 defining an annular cavity 526. A conduit 540, also referred to as a tailpipe, extends through the annular cavity. In one embodiment, the conduit 540 can be spaced apart from the inner surface 532. The tailpipe 540 can facilitate fluid passage through the vibration isolation coupling 500 and to a central passage in the first and second coupling portions. The fluid can take the form of drilling mud that flows to the fragmentation tool 30. The drilling mud can flow through a mud motor (not shown) to provide prime mover power to the fragmentation tool 30. In addition, one or more of the plurality of vibration isolation elements 520 can include a passage 550 that receives one or more conductors that can pass control signals between, for example, the surface control unit 80 and downhole / subsurface tools, devices, sensors, etc. The tailpipe 540, the plurality of vibration isolation elements 520, and the solid annular portion can be integrally formed. The vibration isolation coupling can be modeled using finite element simulation (FE simulation, FE modeling) with different parts of the vibration isolation coupling 140 having different material properties, dimensions, and shapes (e.g., number, size, and shape of the vibration isolation elements, number, length, and width of the slots, or configuration of the central support) to optimize and fine-tune the ratio of bending stiffness to torsional stiffness (BST / TST) to be as large as possible, for example, a ratio greater than 15.

[0094] Some embodiments of the foregoing disclosure are illustrated below:

[0095] Embodiment 1. A vibration isolation coupling for reducing high frequency torsional oscillations in a drill string, the vibration isolation coupling comprising: a first coupling portion comprising an outer surface and an inner surface; a second coupling portion comprising an outer surface and an inner surface portion; and a vibration isolation portion extending between the first coupling portion and the second coupling portion, the vibration isolation portion comprising a first solid annular portion defining a first terminal end of the vibration isolation portion and a second solid annular portion defining a second terminal end of the vibration isolation portion, the vibration isolation portion comprising a plurality of slots extending from the first solid annular portion toward the second solid annular portion forming a plurality of vibration isolation elements, each of the plurality of vibration isolation elements being disconnected from an adjacent vibration isolation element of the plurality of vibration isolation elements by a corresponding slot of the plurality of slots, the plurality of vibration isolation elements enabling torsional rotation of the first coupling portion relative to the second coupling portion.

[0096] Embodiment 2. The vibration isolation coupling of any preceding embodiment, further comprising: a central support, wherein each of the plurality of vibration isolation elements is coupled to the central support by a corresponding connection element of the plurality of connection elements.

[0097] Embodiment 3. The vibration isolation coupling of any preceding embodiment, wherein the central support comprises a central passage.

[0098] Embodiment 4. The vibration isolation coupling of any preceding embodiment, wherein the central support comprises an outer surface portion and a solid cross-section.

[0099] Embodiment 5. The vibration isolation coupling of any preceding embodiment, wherein each of the plurality of vibration isolation elements, the connecting elements, and the central support are integrally formed.

[0100] Embodiment 6. The vibration isolation coupling of any preceding embodiment, wherein one of at least one of the plurality of vibration isolation elements and at least one of the plurality of connecting elements comprises a passage, wherein the passage extends from the first coupling portion and the second coupling portion.

[0101] Embodiment 7. The vibration isolation coupling of any preceding embodiment, wherein the first coupling portion and the second coupling portion comprise threaded portions.

[0102] Embodiment 8. The vibration isolation coupling of any preceding embodiment, wherein the vibration isolation coupling comprises a longitudinal axis and a plurality of slots extending generally parallel to the longitudinal axis.

[0103] Embodiment 9. The vibration isolation coupling of any preceding embodiment, further comprising: a plurality of cavities defined between adjacent ones of the plurality of connecting elements.

[0104] Embodiment 10. The vibration isolation coupling of any preceding embodiment, further comprising a conduit disposed in at least one of the plurality of cavities, the conduit extending through the vibration isolation coupling.

[0105] Embodiment 11. The vibration isolation coupling of any preceding embodiment, wherein each of the plurality of vibration isolation elements comprises a first segment extending outwardly from one of the plurality of connecting elements in a first direction and a second segment extending outwardly from the one of the plurality of connecting elements in a second direction.

[0106] Embodiment 12. The vibration isolation coupling of any preceding embodiment, wherein the second segment is radially inwardly offset relative to the first segment.

[0107] Embodiment 13. The vibration isolation coupling of any preceding embodiment, wherein the vibration isolation portion is integrally formed of different materials.

[0108] Embodiment 14. The vibration isolation coupling of any preceding embodiment, wherein each vibration isolation element of the plurality of vibration isolation elements comprises an outer surface and an inner surface, the inner surface of each vibration isolation element of the plurality of vibration isolation elements defining an annular cavity.

[0109] Embodiment 15. The vibration isolation coupling of any preceding embodiment, further comprising: a tailpipe through the annular cavity, the tailpipe spaced apart from the inner surface of the vibration isolation element, wherein the tailpipe comprises a fluid passage.

[0110] Embodiment 16. The vibration isolation coupling of claim 1, wherein the vibration isolation portion is integrally formed with the first coupling portion and the second coupling portion.

[0111] Embodiment 17. A method of isolating high frequency torsional vibrations from a portion of a drill string connected to another portion of the drill string by a vibration isolation coupling having a first coupling portion connected to a second coupling portion by a vibration isolation portion having a plurality of slots defining a plurality of vibration isolation elements, the method comprising: introducing torsional vibrations into the first coupling portion; and isolating the torsional vibrations from the second coupling portion by torsional oscillation of the vibration isolation portion.

[0112] Embodiment 18. The method of any preceding embodiment, wherein torsionally oscillating the vibration isolation portion comprises elastically bending the plurality of vibration isolation elements.

[0113] Embodiment 19. The method of any preceding embodiment, further comprising: passing a fluid from the first coupling portion through the second coupling portion.

[0114] Embodiment 20. The method of any preceding embodiment, wherein passing the fluid through comprises directing the fluid through a central passage extending through the vibration isolation portion.

[0115] Embodiment 21. The method of any preceding embodiment, wherein the plurality of vibration isolation elements are coupled to the central support by a plurality of connecting elements, and wherein each vibration isolation element of the plurality of vibration isolation elements, the connecting elements, and the central support are integrally formed.

[0116] In the context of describing the application (particularly in the context of the appended claims), the use of the terms “one,” “a,” and “the” and similar referents is to be construed to cover both the singular and the plural, unless otherwise clearly indicated in the context of the specification or claims. Further, it should be noted that the terms “first,” “second,” and the like are used merely to distinguish one element from another, and do not connote any order, quantity, or importance.

[0117] The terms "about" and "substantially" are intended to include the degree of error associated with measuring a particular quantity based on the equipment available at the time of filing the application. For example, "about" and / or "substantially" can include a range of ± 8% or 5%, or 2% of a given value.

[0118] The teachings of the present disclosure can be used in a variety of well operations. These operations can involve treating a formation, a fluid residing in the formation, a wellbore, and / or equipment in the wellbore, such as production tubing, with one or more treatment agents. The 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, cementing agents, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers, and the like. Exemplary well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water injection, cementing, and the like.

[0119] While the application has been described with reference to one or more embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the application without departing from the central scope thereof. Therefore, it is intended that the application not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this application, but that the application will include all embodiments falling within the scope of the claims. Also, in the drawings and the specification, there have been disclosed exemplary embodiments of the application and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, otherwise, the scope of the application thus not to be construed as being limited to the specific embodiments set forth herein but to include all embodiments falling within the scope of the claims.

Claims

1. A vibration isolation coupling for reducing high frequency torsional oscillations in a drill string, comprising: a first coupling portion, the first coupling portion comprising a first outer surface and a first inner surface; a second coupling portion, the second coupling portion comprising a second outer surface and a second inner surface; a vibration isolation portion extending between the first coupling portion and the second coupling portion, the vibration isolation portion comprising a first solid annular portion defining a first terminal end of the vibration isolation portion and a second solid annular portion defining a second terminal end of the vibration isolation portion, the vibration isolation portion comprising a plurality of slots extending from the first solid annular portion toward the second solid annular portion forming a plurality of vibration isolation elements, each slot of the plurality of slots comprising a longitudinal length and a circumferential width, the longitudinal length being greater than the circumferential width, each vibration isolation element of the plurality of vibration isolation elements being disconnected from an adjacent vibration isolation element of the plurality of vibration isolation elements by a corresponding slot of the plurality of slots, the plurality of vibration isolation elements enabling torsional rotation of the first coupling portion relative to the second coupling portion; and a central support, wherein each vibration isolation element of the plurality of vibration isolation elements is coupled to the central support by a corresponding connection element of a plurality of connection elements.

2. The vibration isolation coupling of claim 1, wherein the central support comprises a central passage.

3. The vibration isolation coupling of claim 1, wherein the central support comprises an outer surface portion and a solid cross-section.

4. The vibration isolation coupling of claim 1, wherein each vibration isolation element of the plurality of vibration isolation elements, the connection elements, and the central support are integrally formed.

5. The vibration isolation coupling of claim 1, wherein one of at least one vibration isolation element of the plurality of vibration isolation elements and at least one connection element of the plurality of connection elements comprises a passage, wherein the passage extends from the first coupling portion and the second coupling portion.

6. The vibration isolation coupling of claim 1, wherein the first coupling portion and the second coupling portion comprise threaded portions.

7. The vibration isolation coupling of claim 1, wherein the vibration isolation coupling comprises a longitudinal axis and the plurality of slots extend parallel to the longitudinal axis.

8. The vibration isolation coupling of claim 1, further comprising: a plurality of cavities defined between adjacent connection elements of the plurality of connection elements.

9. The vibration isolation coupling of claim 8, further comprising a conduit disposed in at least one cavity of the plurality of cavities, the conduit extending through the vibration isolation coupling. ​ 10. The vibration isolation coupling of claim 1, wherein each vibration isolation element of the plurality of vibration isolation elements includes a first segment extending outward from one of the plurality of connecting elements in a first direction and a second segment extending outward from the one of the plurality of connecting elements in a second direction.

11. The vibration isolation coupling of claim 1, wherein each vibration isolation element of the plurality of vibration isolation elements includes an outer surface and an inner surface, the inner surface of each vibration isolation element of the plurality of vibration isolation elements defining an annular cavity.

12. A method of isolating high frequency torsional vibrations from a portion of a drill string connected to another portion of the drill string by a vibration isolation coupling of any one of claims 1-11, the vibration isolation coupling having a first coupling portion connected to a second coupling portion by a vibration isolation portion having a plurality of slots defining a plurality of vibration isolation elements, the method comprising: introducing torsional vibrations into the first coupling portion; and isolating the torsional vibrations from the second coupling portion by torsional oscillation of the vibration isolation portion.

13. The method of claim 12, wherein torsionally oscillating the vibration isolation portion includes elastically bending the plurality of vibration isolation elements.

14. The method of claim 12, further comprising: passing a fluid from the first coupling portion through the second coupling portion.

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