VIBRATION-DAMPING SUB INCLUDING A PLURALITY OF ANGLED SHAPED HOLES

Abstract

Provided is a vibration-damping sub, a tool string, and a method. The vibration-damping sub, in one aspect, includes a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool. The vibration-damping sub, according to this aspect, may further include a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves.

Claims

1. A vibration-damping sub, comprising: a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool; and a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves.

2. The vibration-damping sub as recited in claim 1, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 30 degrees relative to perpendicular to the longitudinal axis of the tubular damping body.

3. The vibration-damping sub as recited in claim 1, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 40 degrees relative to perpendicular to the longitudinal axis of the tubular damping body.

4. The vibration-damping sub as recited in claim 1, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of 45 degrees2 degrees relative to perpendicular to the longitudinal axis of the tubular damping body.

5. The vibration-damping sub as recited in claim 1, wherein the opposing ends are a vibration source end and a vibration-sensitive tool end, and further wherein the angle () of each of the plurality of shaped holes points toward the vibration source end.

6. The vibration-damping sub as recited in claim 1, wherein the plurality of shaped holes comprise a first grouping of shaped holes each having a first shape and a first size and a second grouping of shaped holes axially spaced from the first grouping of shaped holes and having one or both of a second shape different than the first shape and a second size different than the first size.

7. The vibration-damping sub as recited in claim 1, wherein the plurality of shaped holes comprise axially spaced rows of circumferentially shaped holes, wherein the circumferentially shaped holes in each row are misaligned with, or at a different spacing than, the circumferentially shaped holes of an adjacent row.

8. The vibration-damping sub as recited in claim 1, wherein the tubular damping body further comprises a plurality of contiguous tubular portions formed of different materials having different mechanical impedances.

9. The vibration-damping sub as recited in claim 8, wherein the plurality of contiguous tubular portions comprise two or more tubular portions axially arranged with respect to one another or two or more tubular portions circumferentially arranged with respect to one another.

10. The vibration-damping sub as recited in claim 1, wherein the plurality of shaped holes comprise smooth inner surfaces.

11. A tool string, comprising: a vibration-sensitive tool; a vibration source coupled to vibration-sensitive tool, the vibration source capable of generating a mechanical vibration in excess of a design threshold for the vibration-sensitive tool; and a vibration-damping sub rigidly coupled between the vibration-sensitive tool and the vibration source, the vibration-damping sub including: a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool; and a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves.

12. The tool string as recited in claim 11, wherein the vibration source comprises a perforating gun supporting one or more shaped charges for perforating a wall of a wellbore, wherein a detonation of the shaped charges generates the mechanical vibration.

13. The tool string as recited in claim 11, wherein the tubular damping body has no damping components that are directly moveably coupled to the tubular damping body.

14. The tool string as recited in claim 11, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 30 degrees relative to perpendicular to the longitudinal axis of the tubular damping body.

15. The tool string as recited in claim 11, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of 45 degrees2 degrees relative to perpendicular to the longitudinal axis of the tubular damping body.

16. The tool string as recited in claim 11, wherein the opposing ends are a vibration source end and a vibration-sensitive tool end, and further wherein the angle () of each of the plurality of shaped holes points toward the vibration source end.

17. The tool string as recited in claim 11, wherein the plurality of shaped holes comprise a first grouping of shaped holes each having a first shape and a first size and a second grouping of shaped holes axially spaced from the first grouping of shaped holes and having one or both of a second shape different than the first shape and a second size different than the first size.

18. The tool string as recited in claim 11, wherein the plurality of shaped holes comprise axially spaced rows of circumferentially shaped holes, wherein the circumferentially shaped holes in each row are misaligned with, or at a different spacing than, the circumferentially shaped holes of an adjacent row.

19. The tool string as recited in claim 11, wherein the tubular damping body further comprises a plurality of contiguous tubular portions formed of different materials having different mechanical impedances.

20. The tool string as recited in claim 19, wherein the plurality of contiguous tubular portions comprise two or more tubular portions axially arranged with respect to one another or two or more tubular portions circumferentially arranged with respect to one another.

21. A method, comprising: lowering a tool string via a conveyance into a wellbore, the tool string including: a vibration-sensitive tool supported on the conveyance; a vibration source coupled to the conveyance and capable of generating a mechanical vibration in excess of a design threshold for the vibration-sensitive tool; and a vibration-damping sub rigidly coupled between the vibration-sensitive tool and the vibration source, the vibration-damping sub including: a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool; and a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves; and operating the vibration source to generate a mechanical wave in excess of a design threshold for the vibration-sensitive tool, the plurality of shaped holes dampening the mechanical wave to below the design threshold for the vibration-sensitive tool.

Description

BRIEF DESCRIPTION

[0004] Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0005] FIG. 1 illustrates a schematic view of a well system designed, manufactured and operated according to one or more embodiments disclosed herein;

[0006] FIG. 2 illustrates a block diagram of the tool string of FIG. 1;

[0007] FIG. 3 illustrates a cross-sectional view of one example configuration of a tool string wherein the vibration source is a perforating (perf) gun and the vibration-sensitive tool is an electronic tool;

[0008] FIGS. 4A through 4J illustrate various different views of a vibration-damping sub designed, manufactured and/or operated according to one or more embodiments of the disclosure;

[0009] FIG. 5 illustrates a flat pattern of the tubular damping body of FIGS. 4A through 4J further detailing one example arrangement of the plurality of shaped holes;

[0010] FIG. 6 illustrates a flat pattern of a vibration-damping sub designed, manufactured and/or operated according to one or more alternative embodiments of the disclosure;

[0011] FIG. 7 illustrates a flat pattern of a vibration-damping sub designed, manufactured and/or operated according to one or more alternative embodiments of the disclosure; and

[0012] FIG. 8 is a Cartesian coordinate system for describing the physics of acoustics through any two of the adjacent materials of different impedances.

DETAILED DESCRIPTION

[0013] In the drawings and descriptions that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. The drawn figures are not necessarily to scale. Certain features of the disclosure may be shown exaggerated in scale or in somewhat schematic form and some details of certain elements may not be shown in the interest of clarity and conciseness. The present disclosure may be implemented in embodiments of different forms.

[0014] Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed herein may be employed separately or in any suitable combination to produce desired results.

[0015] Unless otherwise specified, use of the terms connect, engage, couple, attach, or any other like term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. Unless otherwise specified, use of the terms up, upper, upward, uphole, upstream, or other like terms shall be construed as generally away from the bottom, terminal end of a well; likewise, use of the terms down, lower, downward, downhole, downstream, or other like terms shall be construed as generally toward the bottom, terminal end of a well, regardless of the wellbore orientation. Use of any one or more of the foregoing terms shall not be construed as denoting positions along a perfectly vertical axis. Unless otherwise specified, use of the term subterranean formation shall be construed as encompassing both areas below exposed earth and areas below earth covered by water such as ocean or fresh water.

[0016] The present disclosure is generally directed to mitigating vibration in a tool string to protect a vibration-sensitive tool. The disclosed approach focuses on disrupting the mechanical waves produced from a shock or other vibration source, utilizing interference and acoustic impedance differences to reduce the magnitude of that wave. The wave is intentionally redirected to impose a reduction in intensity before the wave reaches a vibration-sensitive tool. This may include using reflection and refraction waves to destructively interfere with the wave, and to extend the distance the wave must travel prior to reaching the vibration-sensitive tool. The vibration mitigation may act in any or all axes of freedom, as further discussed below.

[0017] Embodiments of the disclosure include a vibration-damping sub coupled between a vibration source and a vibration-sensitive tool. The vibration-damping sub has a specific pattern of shaped holes formed into the wall of the tubular damping body to provide at least a portion of the vibration mitigation. The shaped holes are not merely perforations, but may have shapes and/or arrangements specially configured to impede propagation of the mechanical wave. The shaped holes may be formed by any suitable means, such as stamping, cutting, perforating, molding, or additive manufacturing (e.g., 3D printing). The shapes and arrangement of the shaped holes may be determined, in one or more embodiments, from electronic modeling and thus may vary based on the particular application. The shaped holes in at least some embodiments are described as slots, having a relatively long but narrow form factor, and can have a variety of different shapes from circles, ovals, polygons (e.g., triangles, squares, rectangles, hexagons, etc.), or irregular shapes.

[0018] In accordance with one or more embodiments, the plurality of shaped holes extend through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves. In at least one other embodiment, the plurality of shaped holes extend through the tubing wall at an angle () of at least 10 degrees, if not at least 15 degrees, if not at least 20 degrees, if not at least 25 degrees, if not at least 30 degrees, if not at least 35 degrees, if not at least 40 degrees, relative to perpendicular to the longitudinal axis of the tubular damping body. In at least one other embodiment, the plurality of shaped holes extend through the tubing wall at an angle () ranging from 35 degrees to 55 degrees, if not from 40 degrees to 50 degrees, relative to perpendicular to the longitudinal axis of the tubular damping body. In yet another embodiment, the plurality of shaped holes extend through the tubing wall at an angle () of 45 degrees 2 degrees relative to perpendicular to the longitudinal axis of the tubular damping body.

[0019] The angle (), in one or more embodiments, produces incidence angles of reflection and refraction to destructively interfere with waveforms that are produced at one end of the sub in a manner that reduces the magnitude of the waveform before reaching the other end of the sub. In one or more embodiments, the plurality of shaped holes may be asymmetric in terms of shape and/or arrangement of the shaped holes with respect to a longitudinal axis of a tubular damping body. The asymmetric shape and/or arrangement may generate an asymmetric wave response beneficially disrupting propagation of the mechanical waveform as compared with a symmetric shape and/or arrangement.

[0020] The vibration-damping sub may also incorporate different materials with acoustic impedance differences to reduce magnitudes of the waveforms. The vibration-damping sub may mitigate vibration without reliance on springs, rubberized materials, or moving parts, which may reduce complexity and increase reliability. In one or more embodiments, a plurality of contiguous tubular portions of different mechanical impedances may disrupt the mechanical wave. In one or more embodiments, the plurality of contiguous tubular portions of different mechanical impedances may sufficiently disrupt the mechanical wave without any shaped holes. In one or more other embodiments, the plurality of contiguous tubular portions of different mechanical impedances may be combined with shaped holes to further disrupt the mechanical wave as compared with using shaped holes or different material impedances alone.

[0021] In one or more embodiments, inner surfaces of the slots or other shaped holes may be smooth, e.g., without any appreciable protrusions extending from an inner surface of the shaped holes. By shaping and arranging the shaped holes as disclosed herein, shaped holes with smooth interior surfaces may sufficiently attenuate the mechanical wave without the added structural complexity of a non-smooth inner surface of the shaped holes. This aspect may desirably reduce manufacturing costs and simplify design.

[0022] The disclosed principles are particularly useful in mitigating mechanical shock that certain tools, such as perforating guns, can generate. The disclosed principles are also useful in mitigating other sources of vibration that may be coupled to the tool string. The vibration source may be another part of the tool string itself (e.g., another tool) or some external source coupled to the tool string via the conveyance.

[0023] FIG. 1 illustrates a schematic view of a well system 100 designed, manufactured and operated according to one or more embodiments disclosed herein. The well system 100 may include an assortment of equipment and systems generally understood in the oil and gas industry for constructing and operating a wellbore 110 (e.g., hydrocarbon recovery wellbore including portions 120, 125), and some features are schematically shown, simplified, or omitted for ease of discussion. A support structure 130, such as a mast or derrick, or a crane in the case of a rig less operation, is erected above the earth's surface 115 over the wellbore 110. A support foundation or platform, such as a rig floor 135, is provided at the base of the support structure 130. Although certain drawing features of FIG. 1 depict a land-based oil and gas rig, the present disclosure is useful with other types of rigs, such as offshore platforms or floating rigs used for subsea wells, and in any other geographical location. In those other types of rigs, the earth's surface 115 may alternatively represent the floor of a seabed, and the rig floor 135 may be on an offshore platform or floating rig over the water above the seabed.

[0024] The support structure 130 is capable of supporting the weight of the tool string 150 suspended from the conveyance 140, and may include equipment generally understood in the art for raising and lowering tubular strings or other conveyance in the wellbore 110. The conveyance 140 is depicted here as a tubing string, which may be assembled at the earth's surface 115 by progressively adding tubing segments end to end to reach a desired depth. Examples of a tubing string include a drill string comprising segments of drill pipe connected end to end, a casing string, a completion string, and other tubing strings. In certain wellbore operations, the conveyance 140 may alternatively comprise coiled tubing, wireline, or other conveyance suitable for supporting the tool string 150 as it is conveyed into or out of the wellbore 110. In addition to physical support for raising and lowering the tool string 150, the conveyance 140 may provide fluid communication to the tool string 150, such as for certain hydraulic actuating functions, circulation of wellbore fluids, or production of wellbore fluids. The conveyance 140 may also provide electrical connections between the tool string 150 and earth's surface 115, such as for conveying electrical power or communicating information electronically between the tool string 150 and surface equipment.

[0025] The tool string 150 is coupled to at least one vibration source 160, which may be a vibration-generating tool in the tool string 150. The tool string 150 includes at least one vibration-sensitive tool 170. The vibration source 160 is capable of generating shock or other sources of vibration at a magnitude capable of damaging the vibration-sensitive tool 170. A vibration-damping sub 180 according to this disclosure is coupled between the vibration source 160 and the vibration-sensitive tool 170 to protect the vibration-sensitive tool 170 from potentially damaging vibration from the vibration source 160. In at least one embodiment, the vibration-sensitive tool 170 is positioned uphole of the vibration source 160, with the vibration-damping sub 180 located therebetween. In yet another embodiment, the vibration-sensitive tool 170 is positioned downhole of the vibration source 160, with the vibration-damping sub 180 located therebetween. The vibration source 160 may be directly or indirectly coupled to the vibration-damping sub 180, with or without spacing therebetween. For example, the vibration source 160 may be directly physically coupled to the vibration-damping sub 180, or the vibration source 160 may be spaced along a rigid portion (e.g., tubing) of the conveyance 140. Likewise, the vibration-damping sub 180 may be directly or indirectly coupled to the vibration-sensitive tool 170. As further discussed below, the vibration-damping sub 180 may use a plurality of shaped holes and/or material combinations in the wall of the vibration-damping sub 180 specially configured to interfere with propagation of a mechanical wave. The vibration-damping sub 180 may be considered solid state in the sense that it may optionally provide damping without the use of any moveable parts (e.g., springs, mechanical dampers, or other reciprocating members) moveably coupled with respect to a housing of the vibration-damping sub 180.

[0026] FIG. 2 is a block diagram of the tool string 150 of FIG. 1. The vibration source 160 may be any tool capable of generating a mechanical waveform 162 of sufficient magnitude and/or frequency to damage the vibration-sensitive tool 170 if unmitigated. One example of the vibration source 160 discussed above is a perforating gun, which generates a mechanical shock as a result of firing explosive charges. A mechanical shock (which may be referred to herein simply as shock) is just one possible source of vibration. In one or more embodiments, the shock is a transient physical excitation resulting from a sudden acceleration caused, for example, by an explosion. The shock produces extreme rates of force with respect to time. The shock can be expressed as a vector, with units of an acceleration. A shock pulse can be characterized by its peak acceleration, the duration, and the shape of the shock pulse (half sine, triangular, trapezoidal, etc.). Other vibration sources can also produce damaging vibrations, and this disclosure contemplated both vibrations due to shock as well as other sources and types of vibration. The mechanical waveform 162 may have a waveform with one or more quantifiable waveform properties W.sub.1 such as an amplitude, intensity, energy level, or other properties, the magnitude of which may indicate or relate to the potential for damaging other components.

[0027] The vibration-sensitive tool 170 may be any tool susceptible to damage from the vibration from the vibration source 160 if the vibration is unmitigated. For example, the vibration-sensitive tool 170 may include one or more electronic component 174 and/or mechanical component 176 that are susceptible to the mechanical wave from a shock or other sources of vibration. Examples of vibration-sensitive mechanical components include motors, hydraulic pumps, and solenoid valves. The vibration-sensitive tool 170 may have an objective (e.g., numerical or quantifiable) design threshold for withstanding shock or other sources of mechanical vibration, above which damage is expected. The design threshold may be expressed in terms of one or more of the same quantifiable waveform properties (e.g., amplitude, intensity, energy level, etc.) used to describe the waveform properties W.sub.1 of the vibration source 160. The vibration source 160 may be capable of generating a mechanical vibration in excess of that design threshold, if unmitigated.

[0028] The vibration-damping sub 180 according to one embodiment of the disclosure is coupled between the vibration source 160 and the vibration-sensitive tool 170 to protect the vibration-sensitive tool 170 from damaging vibrations from the vibration source 160. The vibration-damping sub 180 is configured, as further described below in association with various examples, to dampen the mechanical vibration at the vibration source 160 to below the design threshold for the vibration-sensitive tool 170 by the time the mechanical vibration or waveform components thereof reach the vibration-sensitive tool 170. In particular, the vibration-damping sub 180 may utilize reflection and/or refraction to destructively interfere with mechanical waves attempting to propagate along the vibration-damping sub 180 and/or to extend the distance the mechanical wave must travel through the vibration-damping sub 180 prior to reaching the vibration-sensitive tool 170. The result of this attenuation is a reduced-intensity (e.g., attenuated) mechanical waveform 172 with waveform properties W.sub.2 that propagates from the vibration-damping sub 180 to the vibration-sensitive tool 170. The attenuated properties W.sub.2 of the (e.g., attenuated) mechanical waveform 172 are now below the design threshold for the vibration-sensitive tool 170, thereby protecting the vibration-sensitive tool 170 from damage due to the original mechanical waveform 162 generated by shock or other vibration-producing event.

[0029] The vibration source 160, vibration-sensitive tool 170, and vibration-damping sub 180 are shown closely spaced in FIG. 2, but may be at any given spacing along the tool string 150 in which the vibration source 160 could potentially transmit damaging mechanical waves to the vibration-sensitive tool 170 without the vibration-damping sub 180. The vibration source 160 may be directly or otherwise rigidly coupled to the vibration-damping sub 180, such that the mechanical waveform 162 propagates from the vibration source 160 to the vibration-damping sub 180. The vibration-damping sub 180 may be directly or otherwise rigidly coupled to the vibration-sensitive tool 170, such that the attenuated mechanical waveform 172 propagates from the vibration-damping sub 180 to the vibration-sensitive tool 170. This propagation of mechanical waves may occur when there is some sort of rigid coupling 145 between these components, even if the components are not directly coupled to each other. For example, where the vibration source 160, vibration-damping sub 180, and vibration-sensitive tool 170 are spaced apart along the conveyance 140 (e.g., rigid tubular conveyance), the conveyance itself may act as the rigid coupling 145 allowing the mechanical wave to propagate between these components of the tool string 150. Propagation of a mechanical wave may also occur where the rigid coupling 145 is present between the vibration source 160, vibration-damping sub, and vibration-sensitive tool 170, even if the conveyance 140 extending above the tool string 150 is not rigid. For example, perforating guns can be conveyed in some cases on rigid tubing, and other times on a flexible wireline. Even when supported by a relatively flexible wireline, a perforating gun could damage other components that are rigidly coupled to the perforating gun. Furthermore, it generally does not matter whether the vibration source 160 is above, below, or otherwise arranged with respect to the vibration-sensitive tool 170 so long as the vibration-damping sub 180 is coupled therebetween. For example, in the tool string 150, the vibration source 160 is sometimes above the vibration-sensitive tool 170 and other times below the vibration-sensitive tool 170.

[0030] In one or more additional embodiments, a number or type of transitions between the vibration-damping sub 180 and the environment may be adjusted to further dissipate energy created by the vibration source 160 to the environment. For example, the fluid in the wellbore may be used to further dissipate the energy created by the vibration source 160.

[0031] FIG. 3 is a cross-sectional view of one example configuration of a tool string 300 wherein the vibration source 370 is a perforating (perf) gun and the vibration-sensitive tool 360 is an electronic tool. The vibration-sensitive tool 360 is embodied here, by way of example, as a downhole tension tool, but could alternatively be any of a variety of electronic tools with sensitive electronic components (e.g., sensors, processors, controllers, circuit boards, and the like). The vibration source 370 includes a rigid, outer gun body 372 to house and protect the internal components (internals) of the vibration source 370. A structural charge holder 378 inside the outer gun body 372 is configured to hold shaped charges (not shown) in selected firing orientations, which may be radially outwardly and at different azimuthal directions with respect to one another. The shaped charges are configured, when detonated, to focus the effect of their explosive energy in a particular direction. The outer gun body 372 may include a first (e.g., downhole) connector 376 for coupling to other tool string components, such as another perforating gun (not shown). The outer gun body 372 may include a second (e.g., uphole) connector 374 for coupling to a downhole connector 384 of the vibration-damping sub 380. The vibration-damping sub 380 may also include an uphole connector 386 for coupling to a downhole connector 366 of the vibration-sensitive tool 360. The vibration-sensitive tool 360 may include an uphole connector 364 for coupling to another tool string component or to a conveyance 340.

[0032] The various example connectors provide physical (e.g., rigid mechanical) coupling between the vibration source 370 (e.g., perf gun), the vibration-damping sub 380, and the vibration-sensitive tool 360. The connectors may also establish electrical connections or pass-through electrical connectivity between the various components of the tool string 300. For example, the vibration-sensitive tool 360 may have an electrical connection that passes through the vibration-damping sub 380 to the vibration source 370 for providing electrical power and/or signal communication to selectively fire the perf gun. When an electronic firing signal is sent to the perf gun, the shaped charges are detonated, resulting in a shock pulse generating a mechanical wave that may be delivered in both an uphole and downhole directions from the perf gun.

[0033] The mechanical wave generated by the perf gun is generally constrained to propagate through the vibration-damping sub 380 in order to reach the vibration-sensitive tool 360 since the vibration-damping sub 380 is rigidly coupled between the perf gun and the vibration-sensitive tool 360. Losses due to the surrounding fluid will generally be negligible in comparison to the magnitude of the mechanical wave that travels along the vibration-damping sub 380. The vibration-damping sub 380, in one or more embodiments, includes a tubular damping body 382 configured to dampen the vibrations by destructively interfering with the mechanical wave. In particular, the vibration-damping sub 380 in this embodiment has a plurality of axially and circumferentially arranged shaped holes 390 formed through a wall 388 (e.g., tubular wall) of the tubular damping body 382. The shaped holes 390 are a specific pattern (arrangement and shape) formed in the tubular damping body 382 (the shaped holes are not to be confused with the perforations formed in a wellbore casing by firing per charges). The shaped holes 390, in one or more embodiments, pass all the way through the wall 388 of the vibration-damping sub 380, but may alternatively be formed to pass only partially through the wall 388. A mechanical wave imparted at one end of the vibration-damping sub 380 is constrained to pass almost entirely along its tubular damping body 382.

[0034] The arrangement and shapes of shaped holes 390 in the wall 388 provide interference to impede the mechanical wave from propagating along the wall 388. The particular arrangement and shape of the shaped holes 390 may affect the mechanical wave by directing or redirecting the mechanical wave intentionally into certain directions to reduce the magnitude of the wave at one end (e.g., at the downhole connector 384) before reaching the other side of the sub (e.g., the uphole connector 386). This may include using reflection and/or refraction waves to destructively interfere with other waves throughout the vibration-damping sub 380, and to extend the distance the wave must travel through the vibration-damping sub 380 prior to reaching the other side of the vibration-damping sub 380. This may occur without any moving parts (e.g., no springs or reciprocating dampers) coupled to the tubular damping body 382.

[0035] Turning to FIGS. 4A through 4J, illustrated are various different views of a vibration-damping sub 400 designed, manufactured and/or operated according to one or more embodiments of the disclosure. FIG. 4A illustrates a perspective view of the vibration-damping sub 400. FIG. 4B illustrates a side view of the vibration-damping sub 400. FIGS. 4C through 4J illustrate various different cross-sectional views of the vibration-damping sub 400.

[0036] The vibration-damping sub 400, in the illustrated embodiment, includes a tubular damping body 410 having a tubing wall 420 defining a longitudinal axis 425. In this example, the tubular damping body 410 is generally tubular with a circular cross-section. However, other non-circular tubulars may be used and remain within the scope of the disclosure. The vibration-damping sub 400, in the illustrated embodiment, has a length L along the longitudinal axis 425 and a circumference C about the longitudinal axis 425.

[0037] The vibration-damping sub 400, in the illustrated embodiment, additionally includes first and second opposing ends 430, 435 for connecting the tubular damping body 410 within a tool string between a vibration source and a vibration-sensitive tool. In the illustrated embodiment, the first end 430 is a vibration source end (e.g., that end of the tubular damping body 410 positioned more near the vibration source), and the second end 435 is a vibration-sensitive tool end (e.g., that end of the tubular damping body 410 positioned more near the vibration-sensitive tool).

[0038] The vibration-damping sub 400, in the illustrated embodiment, further includes a plurality of shaped holes 440 extending through the tubing wall 420. In one or more embodiments, the plurality of shaped holes 440 are configured to impede propagation of mechanical waves along the tubular damping body 410. Furthermore, in accordance with one embodiment of the disclosure, each of the plurality of shaped holes 440 extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis 425 of the tubular damping body 410, for example to redirect the mechanical waves. The angle () may vary greatly and remain within the scope of the disclosure, but traditionally will fall within the values and/or ranges disclosed above. In at least one embodiment, however, each of the plurality of shaped holes 440 extends through the tubing wall 420 at an angle () of 45 degrees 2 degrees relative to perpendicular to the longitudinal axis 425 of the tubular damping body 410. Furthermore, in at least one embodiment, the angles of each of the plurality of shaped holes 440 point toward the first end 430 (e.g., vibration source end), as shown in the embodiments of FIGS. 4A through 4J. In yet another embodiment, the angles of each of the plurality of shaped holes 440 point away from the first end 430 (e.g., vibration source end).

[0039] In one or more embodiments, such as that shown in FIGS. 4A through 4J, the plurality of shaped holes 440 comprise axially spaced rows 450 of circumferentially shaped holes. In one or more embodiments, the shaped holes 440 in each axially spaced row 450 are misaligned with, or at a different spacing than, the shaped holes 440 of an adjacent axially spaced rows 450. In one or more other embodiments, such as the embodiment of FIGS. 4A through 4J, the plurality of shaped holes 440 comprise a first grouping of shaped holes 460 each having a first shape and a first size and a second grouping of shaped holes 465 axially spaced from the first grouping of shaped holes and having one or both of a second shape different than the first shape and a second size different than the first size.

[0040] Turning briefly to FIG. 5, illustrated is a flat pattern of the tubular damping body 410 of FIGS. 4A through 4J, further detailing one example arrangement of the plurality of shaped holes 440. The flat pattern illustrates the tubular damping body 410 as though it were unrolled and laid out flat, with the length L and circumference C of the tubular wall 420 labeled for reference. The plurality of shaped holes 440 are arranged both longitudinally (e.g., along the length L of the tubular damping body 410) and circumferentially (e.g., along the circumference C of the tubular damping body 410). As the mechanical wave 510 generated by the vibration source (not shown) propagates along the tubular damping body 410, it is disrupted by the plurality of shaped holes 440.

[0041] Turning to FIG. 6, illustrated is a flat pattern of a vibration-damping sub 600 designed, manufactured and/or operated according to one or more alternative embodiments of the disclosure. The vibration-damping sub 600, in the illustrated embodiment of FIG. 6, uses a plurality of tubular portions 620, 630, 640, 650, 660 (e.g., contiguous tubular portions) of different mechanical impedances Z.sub.1-Z.sub.5 to disrupt the mechanical wave 610. The different tubular portions are circumferentially extending, and are longitudinally arranged with respect to each other along the tubular damping body 410. In one or more embodiments, every pair of adjacent tubular portions has a different impedance. For example, adjacent tubular portions 620 and 630 have respective impedances Z.sub.1 and Z.sub.2, adjacent tubular portions 630 and 640 have respective impedances Z.sub.2 and Z.sub.3, adjacent tubular portions 640 and 650 have respective impedances Z.sub.3 and Z.sub.4, adjacent tubular portions 650 and 660 have respective impedances Z.sub.4 and Z.sub.5. In certain embodiments, some of the materials can be reused at different locations along the tubular damping body 410 to provide different combinations of impedances from a finite set of material and impedance options. For example, in at least one embodiment, respective impedances Z.sub.4 and Z.sub.2 are equal, and Z.sub.1 and Z.sub.5 are equal. Nevertheless, the variation of mechanical impedances may be ordered or randomized.

[0042] Turning to FIG. 7, illustrated is a flat pattern of a vibration-damping sub 700 designed, manufactured and/or operated according to one or more alternative embodiments of the disclosure. The vibration-damping sub 700 of FIG. 7, in one or more embodiments, uses the longitudinally arranged tubular portions 620, 630, 640, 650, 660, along with a plurality of other portions 720, 730, 740, 750, 760, 770 circumferentially-arranged with respect to each other. The tubular portions 620, 630, 640, 650, 660, 720, 730, 740, 750, 760, 770 are of various mechanical impedances, to disrupt the mechanical wave 710. Other configurations are within the scope of this disclosure including a combination of two or more axially-arranged tubular portions with two or more circumferentially arranged portions.

[0043] In either example of FIG. 6 or FIG. 7, the difference in acoustic impedance of adjacent materials may result in both a reflected wave and a refracted wave as generally understood apart from the specific teachings of this disclosure. Thus, by including several different materials of different impedances, the mechanical wave 610, 710 may be significantly disrupted as it traverses from one tubular portion to the next.

[0044] The physics of shock and vibration may be described for a given reference frame. For example, FIG. 8 is a Cartesian coordinate system 800 for describing the physics of acoustics through any two of the adjacent materials of different impedances. Where Z.sub.1 is the Acoustic Impedance of the initial medium. Z.sub.2 is the Acoustic Impedance of the secondary medium. M.sub.i is the Magnitude of the incident wave. M.sub.r is the Magnitude of the reflected wave. M.sub.t is the Magnitude of the refracted wave. .sub.i=Angle of Incidence. .sub.r=Angle of Reflection. .sub.i=.sub.r. .sub.t=sin1(Z.sub.2(sin(.sub.i)/Z.sub.1). M.sub.t=M.sub.i*2*(Z.sub.2)/(Z.sub.2+Z.sub.1). M.sub.r=M.sub.i*(Z.sub.2Z.sub.1)/(Z.sub.2+Z.sub.1). It can be seen that, for adjacent materials of different impedances, there will generally be some reflection and refraction dependent on the impedance difference between the adjacent materials. By providing numerous materials of different impedances, this reflection and refraction is compounded as a mechanical wave attempts to propagate through a tubular damping body according to any of the disclosed embodiments. For example, this may describe the wave behavior at an interface between two contiguous, solid tubing portions of a damping body have different impedances (e.g., FIGS. 6 and 7) or at the interface between a solid damping body and a slot occupied by a fluid (e.g., an air or liquid) in any of the perforated/slotted embodiments.

[0045] Although not expressly shown, a selected pattern of shaped holes in accordance with the disclosure may be combined with a selected arrangement of tubular portions of different impedances (e.g., FIG. 6 or 7), to provide further disruption to the mechanical wave.

[0046] For simplicity, examples have been discussed in terms of a flat pattern and a Cartesian reference frame. It should be recognized, however, that these principles of using destructive interference may be applied in any or all axes of freedom of a Cartesian coordinate system (X,Y, Z) or other reference coordinate system (e.g., polar or cylindrical coordinates). The dynamics of such a system may include, for example, changes in radius, twist, bending, and all 6 axes of freedom.

[0047] This disclosure presents a finite set of example embodiments of different patterns of slots/shaped holes and/or different material impedances. It should be recognized, however, that a myriad of other patterns of shaped holes and/or arrangement of materials with different impedances may be devised within the scope of this disclosure for mitigating vibration in a downhole tool string. A specific configuration may be custom-developed for specific applications, such as through various computer modeling and design simulations. A design method according to this disclosure may include either iterative modeling or the application of machine-learning models to identify the optimal configuration for a vibration-damping sub for a given application. The disclosed embodiments may include any of the various features disclosed herein, including one or more of the following statements.

[0048] Aspects disclosed herein include: [0049] A. A vibration-damping sub, the vibration-damping sub including: 1) a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool; and 2) a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves. [0050] B. A tool string, the tool string including: 1) a vibration-sensitive tool; 2) a vibration source coupled to vibration-sensitive tool, the vibration source capable of generating a mechanical vibration in excess of a design threshold for the vibration-sensitive tool; and 3) a vibration-damping sub rigidly coupled between the vibration-sensitive tool and the vibration source, the vibration-damping sub including: 1) a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool; and 2) a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves. [0051] C. A method, the method including: 1) lowering a tool string via a conveyance into a wellbore, the tool string including: a) a vibration-sensitive tool supported on the conveyance; b) a vibration source coupled to the conveyance and capable of generating a mechanical vibration in excess of a design threshold for the vibration-sensitive tool; and c) a vibration-damping sub rigidly coupled between the vibration-sensitive tool and the vibration source, the vibration-damping sub including: i) a tubular damping body having a tubing wall defining a longitudinal axis and opposing ends for connecting the tubular damping body within a tool string between a vibration source and a vibration-sensitive tool; and ii) a plurality of shaped holes extending through the tubing wall and configured to impede propagation of mechanical waves along the tubular damping body, wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 5 degrees relative to perpendicular to the longitudinal axis of the tubular damping body for redirecting the mechanical waves; and 2) operating the vibration source to generate a mechanical wave in excess of a design threshold for the vibration-sensitive tool, the plurality of shaped holes dampening the mechanical wave to below the design threshold for the vibration-sensitive tool.

[0052] Aspects A, B, and C may have one or more of the following additional elements in combination: Element 1: wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 30 degrees relative to perpendicular to the longitudinal axis of the tubular damping body. Element 2: wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of at least 40 degrees relative to perpendicular to the longitudinal axis of the tubular damping body. Element 3: wherein each of the plurality of shaped holes extends through the tubing wall at an angle () of 45 degrees2 degrees relative to perpendicular to the longitudinal axis of the tubular damping body. Element 4: wherein the opposing ends are a vibration source end and a vibration-sensitive tool end, and further wherein the angles of each of the plurality of shaped holes point toward the vibration source end. Element 5: wherein the plurality of shaped holes comprise a first grouping of shaped holes each having a first shape and a first size and a second grouping of shaped holes axially spaced from the first grouping of shaped holes and having one or both of a second shape different than the first shape and a second size different than the first size. Element 6: wherein the plurality of shaped holes comprise axially spaced rows of circumferentially shaped holes, wherein the circumferentially shaped holes in each row are misaligned with, or at a different spacing than, the circumferentially shaped holes of an adjacent row. Element 7: wherein the tubular damping body further comprises a plurality of contiguous tubular portions formed of different materials having different mechanical impedances. Element 8: wherein the plurality of contiguous tubular portions comprise two or more tubular portions axially arranged with respect to one another or two or more tubular portions circumferentially arranged with respect to one another. Element 9: wherein the plurality of shaped holes comprise smooth inner surfaces. Element 10: wherein the vibration source comprises a perforating gun supporting one or more shaped charges for perforating a wall of the wellbore, wherein a detonation of the shaped charges generates the mechanical vibration. Element 11: wherein the tubular damping body has no damping components that are directly moveably coupled to the tubular damping body.

[0053] Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.