Patent Application
20190284882
The present invention generally relates to downhole operations and systems for damping vibrations of the downhole systems during operation.
Boreholes are drilled deep into the earth for many applications such as carbon dioxide sequestration, geothermal production, and hydrocarbon exploration and production. In all of the applications, the boreholes are drilled such that they pass through or allow access to a material (e.g., a gas or fluid) contained in a formation (e.g., a compartment) located below the earth's surface. Different types of tools and instruments may be disposed in the boreholes to perform various tasks and measurements.
In operation, the downhole components may be subject to vibrations that can impact operational efficiencies. For example, severe vibrations in drillstrings and bottomhole assemblies can be caused by cutting forces at the bit or mass imbalances in downhole tools such as mud motors. Impacts from such vibrations can include, but are not limited to, reduced rate of penetration, reduced quality of measurements, and excess fatigue and wear on downhole components, tools, and/or devices.
Disclosed is a device for transferring torque to a drill bit in a borehole having a borehole axis including a support element configured to rotate in the borehole about the borehole axis, a torque transferring element configured to transfer torque from the support element to the drill bit and further configured to isolate torsional oscillations that are created at the drill bit from the support element, a blocking element configured to block rotation of the torque transferring element relative to the support element about the borehole axis in at least one direction, and a bearing element between the support element and the drill bit.
Also disclosed is a method of transferring torque to a drill bit in a borehole having a borehole axis. The method includes rotating a support element about the borehole axis, transferring, with a torque transferring element, torque from the support element to the drill bit, isolating with a torsional flexible element torsional oscillations that are created at the drill bit from the support element, blocking, with a blocking element, rotation of the torque transferring element relative to the support element about the borehole axis in at least one direction, and bearing, with a bearing element, a torque transferring element configured to transfer torque from the support element to the drill bit and further configured to isolate torsional oscillations that are created at the drill bit from the support element.
Further disclosed is a system for drilling a borehole into the earth's subsurface, the system including a drill bit configured to rotate and penetrate through the earth's subsurface, and a vibration isolation device configured to isolate vibration that is caused at the drill bit, the vibration having an amplitude. The amplitude of the vibration below the vibration isolation device is 20% higher than the amplitude of the vibration above the vibration isolation device.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein like elements are numbered alike, in which:
During drilling operations, a suitable drilling fluid 31 (also referred to as the “mud”) from a source or mud pit 32 is circulated under pressure through the drill string 20 by a mud pump 34. The drilling fluid 31 passes into the drill string 20 via a desurger 36, fluid line 38 and the kelly joint 21. The drilling fluid 31 is discharged at the borehole bottom 51 through an opening in the disintegrating tool 50. The drilling fluid 31 circulates uphole through the annular space 27 between the drill string 20 and the borehole 26 and returns to the mud pit 32 via a return line 35. A sensor S1 in the fluid line 38 provides information about the fluid flow rate. A surface torque sensor S2 and a sensor S3 associated with the drill string 20 respectively provide information about the torque and the rotational speed of the drill string. Additionally, one or more sensors (not shown) associated with line 29 are used to provide the hook load of the drill string 20 and about other desired parameters relating to the drilling of the borehole 26. The system may further include one or more downhole sensors 70 located on the drill string 20 and/or the BHA 90.
In some applications the disintegrating tool 50 is rotated by only rotating the drill pipe 22. However, in other applications, a drilling motor 55 (for example, a mud motor) disposed in the drilling assembly 90 is used to rotate the disintegrating tool 50 and/or to superimpose or supplement the rotation of the drill string 20. In either case, the rate of penetration (ROP) of the disintegrating tool 50 into the earth formation 60 for a given formation and a given drilling assembly largely depends upon the weight on bit and the drill bit rotational speed. In one aspect of the embodiment of
A surface control unit 40 receives signals from the downhole sensors 70 and devices via a transducer 43, such as a pressure transducer, placed in the fluid line 38 as well as from sensors S1, S2, S3, hook load sensors, RPM sensors, torque sensors, and any other sensors used in the system and processes such signals according to programmed instructions provided to the surface control unit 40. The surface control unit 40 displays desired drilling parameters and other information on a display/monitor 42 for use by an operator at the rig site to control the drilling operations. The surface control unit 40 contains a computer, memory for storing data, computer programs, models and algorithms accessible to a processor in the computer, a recorder, such as tape unit, memory unit, etc. for recording data and other peripherals. The surface control unit 40 also may include simulation models for use by the computer to processes data according to programmed instructions. The control unit responds to user commands entered through a suitable device, such as a keyboard. The surface control unit 40 is adapted to activate alarms 44 when certain unsafe or undesirable operating conditions occur.
The drilling assembly 90 also contains other sensors and devices or tools for providing a variety of measurements relating to the formation surrounding the borehole and for drilling the borehole 26 along a desired path. Such devices may include a device for measuring the formation resistivity near and/or in front of the drill bit, a gamma ray device for measuring the formation gamma ray intensity and devices for determining the inclination, azimuth and position of the drill string. A formation resistivity tool 64, made according an embodiment described herein may be coupled at any suitable location, including above a lower kick-off subassembly 62, for estimating or determining the resistivity of the formation near or in front of the disintegrating tool 50 or at other suitable locations. An inclinometer 74 and a gamma ray device 76 may be suitably placed for respectively determining the inclination of the BHA and the formation gamma ray intensity. Any suitable inclinometer and gamma ray device may be utilized. In addition, an azimuth device (not shown), such as a magnetometer or a gyroscopic device, may be utilized to determine the drill string azimuth. Such devices are known in the art and therefore are not described in detail herein. In the above-described exemplary configuration, the drilling motor 55 transfers power to the disintegrating tool 50 via a shaft that also enables the drilling fluid to pass from the drilling motor 55 to the disintegrating tool 50. In an alternative embodiment of the drill string 20, the drilling motor 55 may be coupled below the resistivity measuring device 64 or at any other suitable place.
Still referring to
The above-noted devices transmit data to a downhole telemetry system 72, which in turn transmits the received data uphole to the surface control unit 40. The downhole telemetry system 72 also receives signals and data from the surface control unit 40 and transmits such received signals and data to the appropriate downhole devices. In one aspect, a mud pulse telemetry system may be used to communicate data between the downhole sensors 70 and devices and the surface equipment during drilling operations. A transducer 43 placed in the fluid line 38 (e.g., mud supply line) detects the mud pulses responsive to the data transmitted by the downhole telemetry system 72. Transducer 43 generates electrical signals in response to the mud pressure variations and transmits such signals via a conductor 45 to the surface control unit 40. In other aspects, any other suitable telemetry system may be used for two-way data communication (e.g., downlink and uplink) between the surface and the BHA 90, including but not limited to, an acoustic telemetry system, an electro-magnetic telemetry system, an optical telemetry system, a wired pipe telemetry system which may utilize wireless couplers or repeaters in the drill string or the borehole. The wired pipe telemetry system may be made up by joining drill pipe sections, wherein each pipe section includes a data communication link, such as a wire, that runs along the pipe. The data connection between the pipe sections may be made by any suitable method, including but not limited to, hard electrical or optical connections, induction, capacitive, resonant coupling, such as electromagnetic resonant coupling, or directional coupling methods. In case a coiled-tubing is used as the drill pipe 22, the data communication link may be run along a side of the coiled-tubing.
The drilling system described thus far relates to those drilling systems that utilize a drill pipe to convey the drilling assembly 90 into the borehole 26, wherein the weight on bit is controlled from the surface, typically by controlling the operation of the drawworks. However, a large number of the current drilling systems, especially for drilling highly deviated and horizontal boreholes, utilize coiled-tubing for conveying the drilling assembly downhole. In such application a thruster is sometimes deployed in the drill string to provide the desired force on the drill bit. Also, when coiled-tubing is utilized, the tubing is not rotated by a rotary table but instead it is injected into the borehole by a suitable injector while the downhole motor, such as drilling motor 55, rotates the disintegrating tool 50. For offshore drilling, an offshore rig or a vessel is used to support the drilling equipment, including the drill string.
Still referring to
Liner drilling can be one configuration or operation used for providing a disintegrating device becomes more and more attractive in the oil and gas industry as it has several advantages compared to conventional drilling. One example of such configuration is shown and described in commonly owned U.S. Pat. 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 herein by reference in its entirety. Importantly, despite a relatively low rate of penetration, the time of getting the liner to target is reduced because the liner is run in-hole while drilling the borehole simultaneously. This may be beneficial in swelling formations where a contraction of the drilled well can hinder an installation of the liner later on. Furthermore, drilling with liner in depleted and unstable reservoirs minimizes the risk that the pipe or drill string will get stuck due to hole collapse.
Although
Severe vibrations in drillstrings and bottomhole assemblies during drilling operations can be caused by cutting forces at the bit or mass imbalances in downhole tools such as drilling motors. Such vibrations can result in reduced rate of penetration, reduced quality of measurements made by tools of the bottomhole assembly, and can result in wear, fatigue, and/or failure of downhole components. As appreciated by those of skill in the art, different vibrations exist, such as lateral vibrations, axial vibrations, and torsional vibrations. For example, stick/slip of the whole drilling system and high-frequency torsional oscillations (“HFTO”) are both types of torsional vibrations. The terms “vibration,” “oscillation,” as well as “fluctuation,” are used with the same broad meaning of repeated and/or periodic movements or periodic deviations of a mean value, such as a mean position, a mean velocity, and a mean acceleration. In particular, these terms are not meant to be limited to harmonic deviations, but may include all kinds of deviations, such as, but not limited to periodic, harmonic, and statistical deviations. Torsional vibrations may be excited by self-excitation mechanisms that occur due to the interaction of the drill bit or any other cutting structure such as a reamer bit and the formation. The main differentiator between stick/slip and HFTO is the frequency and typical mode shapes: For example, HFTO have a frequency that is typically above 50 Hz compared to stick/slip torsional vibrations that typically have frequencies below 1 Hz. Moreover, the excited mode shape of stick/slip is typically a first mode shape of the whole drilling system whereas the mode shape of HFTO can be of higher order and are commonly localized to smaller portions of the drilling system with comparably high amplitudes at the point of excitation that may be the bit or any other cutting structure (such as a reamer bit), or any contact between the drilling system and the formation (e.g., by a stabilizer).
Due to the high frequency of the vibrations, HFTO correspond to high acceleration and torque values along the BHA. Those skilled in the art will appreciate that for torsional movements, one of acceleration, force, and torque is always accompanied by the other two of acceleration, force, and torque. In that sense, acceleration, force, and torque are equivalent in the sense that none of these can occur without the other two. The loads of high frequency vibrations can have negative impacts on efficiency, reliability, and/or durability of electronic and mechanical parts of the BHA. Embodiments provided herein are directed to providing torsional vibration damping upon the downhole system to mitigate HFTO. In some embodiments of the present disclosure, the torsional vibration damping can be activated if a threshold of a measured property, such as a torsional vibration amplitude or frequency is achieved within the system.
In accordance with a non-limiting embodiment provided herein, a torsional vibration damping system may be based on friction dampers. For example, according to some embodiments, friction between two parts, such as two interacting bodies, in the BHA or drill string can dissipate energy and reduce the level of torsional oscillations, thus mitigating the potential damage caused by high frequency vibrations. Preferably, the energy dissipation of the friction damper is at least equal to the HFTO energy input caused by the bit-rock interaction.
Friction dampers, as provided herein, can lead to a significant energy dissipation and thus mitigation of torsional vibrations. When two components or interacting bodies are in contact with each other and move relative to each other, a friction force acts in the opposite direction of the velocity of the relative movement between the contacting surfaces of the components or interacting bodies. The friction force leads to a dissipation of energy.
Generally, friction force FR depends on the normal force as described in the equation FR=μ ·FN, with friction coefficient μ. Generally, the friction coefficient μ is a function of velocity. In the case that the relative speed between two interacting bodies is zero (ν=0), the static friction force FS is related to the normal force component FN by the equation FS=μ0·FN with the static friction coefficient μ0. In the case that the relative speed between the two interacting bodies is not zero (ν ≠0), the friction coefficient is known as dynamic friction coefficient μ. If the relative velocity is further decreased to negative values (i.e., if the direction the relative movement of the two interacting bodies is switched to the opposite), the friction force or torque switches to the opposite direction with a high absolute value corresponding to a step from a positive maximum to a negative minimum at point 204 in plot 200. That is, the friction force versus velocity shows a sign change at the point where the velocity changes the sign and is discontinuous at point 204 in plot 200. Velocity-weakening characteristic is a well-known effect between interacting bodies that are frictionally connected. The velocity-weakening characteristic of the contact force or torque is assumed to be a potential root cause for stick/slip. Velocity-weakening characteristic may also be achieved by utilizing dispersive fluid with a higher viscosity at lower relative velocities and a lower viscosity at higher relative velocities. If a dispersive fluid is forced through a relatively small channel, the same effect can be achieved in that the flow resistance is relatively high or low at low or high relative velocities, respectively.
With reference to
Referring again to
As will be appreciated by those of skill in the art, the weakening characteristic of the contact force or torque with respect to the relative velocity as illustrated in
The corresponding hysteresis is depicted in
Referring again to
Friction dampers in accordance with some embodiments of the present disclosure will now be described. The friction dampers are installed on or in a drilling system, such as drilling system 10 shown in
For example, turning to
In the case of frictional forces, the difference between the minimum and maximum friction force is positively dependent on the normal force and the static friction coefficient. The dissipated energy increases with friction force and the harmonic displacement, but, only in a slip phase, energy is dissipated. In a sticking phase, the relative displacement between the friction interfaces and the dissipated energy is zero. The upper amplitude limit of the sticking phase increases linearly with the normal force and the friction coefficient in the contact interface. The reason is that the reactive force in the contact interface, J{umlaut over (x)}=FNμHr, that can be caused by the inertia J of one of the contacting bodies if it is accelerated with {umlaut over (x)} has to be higher than the torque MH=FNμHr that defines the limit between sticking and slipping. As used herein, FN is the normal force and μH is the effective friction coefficient and r is the effective or mean radius of the friction contact area.
Similar mechanisms apply if the contact force is caused by a displacement and spring element. The acceleration {umlaut over (x)} of the contact area can be due to an excitation of a mode and is dependent upon the corresponding mode shape, as further discussed below with respect to
The normal force and friction force have to be adjusted to guarantee a slipping phase in an adequate or tolerated amplitude range. A tolerated amplitude range can be defined by an amplitude that is between zero and the limits of loads that are, for example, given by design specifications of tools and components. A limit could also be given by a percentage of the expected amplitude without the damper. The dissipated energy that can be compared to the energy input, e.g., by a forced or self-excitation, is one measure to judge the efficiency of a damper. Another measure is the provided equivalent damping of the system that is proportional to the ratio of the dissipated energy in one period of a harmonic vibration to the potential energy during one period of vibration in the system. This measure is especially effective in case of self-excited systems. In the case of self-excited systems, the excitation can be approximated by a negative damping coefficient and both the equivalent damping and the negative damping can be directly compared. The damping force that is provided by the damper is nonlinear and strongly amplitude dependent.
As shown in
The curve is dependent on different parameters. It is beneficial to have a high normal force but a sliding phase with as low an amplitude as possible. In the case of the inertia mass, this can be achieved by a high mass or by placing the contact interface at a point of high acceleration. In the case of contacting interfaces, a high relative displacement in comparison to the amplitude of the mode is beneficial. Therefore, an optimal placement of the damping device according to a high amplitude or relative amplitude is important. This can be achieved by using simulation results, as discussed below. The normal force and the friction coefficient can be used to shift the curve to lower or higher amplitudes but does not have a high influence on the damping maximum. If more than one friction damper is implemented, this would lead to a superposition of similar curves shown in
Referring again to
The second element 712 has a moment of inertia J. When HFTO occurs during operation of the downhole system 702, both the downhole system 702 and the second element 712 are accelerated according to a mode shape. Exemplary results of such operation are shown in
Due to the tangential acceleration and the inertia of the second element 712, relative inertial forces occur between the second element 712 and the first element 710. If these inertial forces exceed a threshold between sticking and slipping, i.e., if these inertial forces exceed static friction force between the first element 710 and the second element 710, a relative movement between the elements 710, 712 will occur that leads to energy dissipation. In such arrangements, the accelerations, the static and/or dynamic friction coefficient, and the normal force determine the amount of dissipated energy. For example, the moment of inertia J of the second element 712 determines the relative force that has to be transferred between the first element 710 and the second element 712. High accelerations and moments of inertia increase the tendency for slipping at the contact surface 714 and thus lead to a higher energy dissipation and equivalent damping ratio provided by the damper.
Due to the energy dissipation that is caused by frictional movement between the first element 710 and the second element 712, heat and wear will be generated on the first element 710 and/or the second element 712. To keep the wear below an acceptable level, materials can be used for the first and/or second elements 710, 712 that can withstand the wear. For example, diamonds or polycrystalline diamond compacts can be used for, at least, a portion of the first and/or second elements 710, 712. Alternatively, or in addition, coatings may help to reduce the wear due to the friction between the first and second elements 710, 712. The heat can lead to high temperatures and may impact reliability or durability of the first element 710, the second element 712, and/or other parts of the downhole system 702. The first element 710 and/or the second element 712 may be made of a material with high thermal conductivity or high heat capacity and/or may be in contact with a material with high thermal conductivity or heat capacity.
Such materials with high thermal conductivity include, but are not limited to, metals or compounds including metal, such as copper, silver, gold, aluminum, molybdenum, tungsten or thermal grease comprising fat, grease, oil, epoxies, silicones, urethanes, and acrylates, and optionally fillers such as diamond, metal, or chemical compounds including metal (e.g., silver, aluminum in aluminum nitride, boron in boron nitride, zinc in zinc oxide), or silicon or chemical compounds including silicon (e.g., silicon carbide). In addition or alternatively, one or both of the first element 710 and the second element 712 may be in contact with a flowing fluid, such as the drilling fluid, that is configured to remove heat from the first element 710 and/or the second element 712 in order to cool the respective element 710, 712. Further, an amplitude limiting element (not shown), such as a key, a recess, or a spring element may be employed and configured to limit the energy dissipation to an acceptable limit that reduces the wear. When arranging the damping system 700, a high normal force and/or static or dynamic friction coefficient will prevent a relative slipping motion between the first element 710 and the second element 712, and in such situations, no energy will be dissipated. In contrast, a low normal force and/or static or dynamic friction coefficient can lead to a low friction force, and slipping will occur but the dissipated energy is low. In addition, low normal force and/or static or dynamic friction coefficient may lead to the case that the friction at the outer surface of the second element 712, e.g., between the second element 712 and the formation 708, is higher than the friction between first element 710 and second element 712, thus leading to the situation that the relative velocity between first element 710 and second element 712 is not equal to or close to zero but is in the range of the mean velocity between downhole system 702 and formation 708. As such, the normal force and the static or dynamic friction coefficient may be adjusted (e.g., by using the adjusting element 716) to achieve an optimized value for energy dissipation.
This can be done by adjusting the normal force FN, the static friction coefficient μ0, the dynamic friction coefficient μ, or combinations thereof. The normal force FN can be adjusted by positioning the adjusting element 716 and/or by actuators that generate a force on one of the first and second elements with a component perpendicular to the contact surface of first and second element, by adjusting the pressure regime around first and second element, or by increasing or decreasing an area where a pressure is acting on. For example, by increasing the outer pressure that acts on the second element, such as the mud pressure, the normal force FN will be increased as well. Adjusting the pressure of the mud downhole may be achieved by adjusting the mud pumps (e.g., mud pumps 34 shown in
The normal force FN may also be adjusted by a biasing element (not shown), such as a spring element, that applies force on the second element 712, e.g. a force in an axial direction away from or toward the first element 710. Adjusting the normal force FN may also be done in a controlled way based on an input received from a sensor. For example, a suitable sensor (not shown) may provide one or more parameter values to a controller (not shown), the parameter value(s) being related to the relative movement of the first element 710 and the second element 712 or the temperature of one or both of the first element 710 and the second element 712. Based on the parameter value(s), the controller may provide instruction to increase or decrease the normal force FN. For example, if the temperature of one or both of the first element 710 and the second element 712 exceeds a threshold temperature, the controller may provide instruction to decrease the normal force FN to prevent damage to one or both of the first element 710 and the second element 712 due to high temperatures. Similarly, for example, if a distance, velocity, or acceleration of the second element 712 relative to the first element 710 exceeds a threshold, the controller may provide instructions to increase or decrease the normal force FN to ensure optimal energy dissipation. By monitoring the parameter value, the normal force FN may be controlled to achieve desired results over a time period. For instance, the normal force FN may be controlled to provide optimal energy dissipation while keeping the temperature of one or both of the first element 710 and the second element 712 below a threshold for a drilling run or a portion thereof.
Additionally, the static or dynamic friction coefficient can be adjusted by utilizing different materials, for example, without limitation, material with different stiffness, different roughness, and/or different lubrication. For example, a surface with higher roughness often increases the friction coefficient. Thus, the friction coefficient can be adjusted by choosing a material with an appropriate friction coefficient for at least one of the first and the second element or a part of at least one of the first and second element. The material of first and/or second element may also have an effect on the wear of the first and second element. To keep the wear low of the first and second element it is beneficial to choose a material that can withstand the friction that is created between the first and second elements. The inertia, the friction coefficient, and the expected acceleration amplitudes (e.g., as a function of mode shape and eigenfrequency) of the second element 712 are parameters that determine the dissipated energy and also need to be optimized. The critical mode shapes and acceleration amplitudes can be determined from measurements or calculations or based on other known methods as will be appreciated by those of skill in the art. Examples are a finite element analysis or the transfer matrix method or finite differences method and based on this a modal analysis. The placement of the friction damper is optimal where a high relative displacement or acceleration is expected.
Turning now to
As illustratively shown in
For example, a first damping location 908 is close to the bit of downhole system 900 and mainly damps the first and third torsional oscillations (corresponding to mode shapes 902, 906) and provides some damping with respect to the second torsional oscillation (corresponding to mode shape 904). That is, the first damping location 908 to be approximately at a peak of the third torsional oscillation (corresponding to mode shape 906), close to peak of the first torsional oscillation mode shape 902, and about half-way to peak with respect to the second torsional oscillation mode shape 904.
A second damping location 910 is arranged to again mainly provide damping of the third torsional oscillation mode shape 906 and provide some damping with respect to the first torsional oscillation mode shape 902. However, in the second damping location 910, no damping of the second torsional oscillation mode shape 904 will occur because the second torsional oscillation mode shape 904 is nearly zero at the second damping location 910.
Although only two locations are shown in
Due to the high amplitudes at the drill bit, for example, one good location of a damper is close to or even within the drill bit. Further, the first and second elements are not limited to a single body, but can take any number of various configurations to achieve desired damping. That is, multiple body (multi-body) first or second elements (e.g., friction damping devices) with each body having the same or different normal forces, friction coefficients, and moments of inertia can be employed. Such multiple-body element arrangements can be used, for example, if it is uncertain which mode shape and corresponding acceleration is expected at a given position along a downhole system.
For example, two or more element bodies that can achieve different relative slipping motion between each other to dissipate energy may be used. The multiple bodies of the first element can be selected and assembled with different static or dynamic friction coefficients, angles between the contact surfaces, and/or may have other mechanisms to influence the amount of friction and/or the transition between sticking and slipping. Several amplitude levels, excited mode shapes, and/or natural frequencies can be damped with such configurations. For example, turning to
Turning now to
The contact between the three bodies 1118, 1120, 1128 may be established, maintained, or supported by elastic connection elements such as spring elements between two or more of the bodies 1118, 1120, 1128. In addition, or alternatively, the first body 1118 may have a first static or dynamic friction coefficient pi and a first force FN1 at the first contact surface 1122, the second body 1120 may have a second static or dynamic friction coefficient μ2 and a second force FN2 at the second contact surface 1124, and the third body 1128 may have a third static or dynamic friction coefficient μ3 and a third force FN3 at the third contact surface 1130.
In addition, or alternatively, the first body 1118 and the third body 1128 may have a fourth force FN13 and a fourth static or dynamic friction coefficient μ13 between each other at a contact surface between the first body 1118 and the third body 1128. Similarly, the third body 1128 and the second body 1120 may have a fifth force FN32 and a fifth static or dynamic friction coefficient μ32 between each other at a contact surface between the third body 1128 and the second body 1120.
Further, the first body 1118 can have a first moment of inertia J1, the second body 1120 can have a second moment of inertia J2, and the third body 1128 can have a third moment of inertia J3. In some embodiments, the static or dynamic friction coefficients μ1, μ2, μ3, μ13, μ32, the forces FN1, FN2, FN3, F13, F32, and the moment of inertia J1, J2, J3 can be selected to be different than each other so that the product μi·Fi (with i=1, 2, 3, 13, 32) are different for at least a subrange of the relative velocities of first element 1110, first body 1118, second body 1120, and third body 1128. Moreover, the static or dynamic friction coefficients and normal forces between adjacent bodies can be selected to achieve different damping effects.
Although shown and described with respect to a limited number of embodiments and specific shapes, relative sizes, and numbers of elements, those of skill in the art will appreciate that the damping systems of the present disclosure can take any configuration. For example, the shapes, sizes, geometries, radial placements, contact surfaces, number of bodies, etc. can be selected to achieve a desired damping effect. While in the arrangement that is shown in
Turning now to
The movable portion 1234 can have any desired length that may be related to the mode shapes as shown in
As such, even though it may not be known where the exact location of mode maxima or minima is during a downhole deployment, it is assured that the second element 1212 is in frictional contact with the first element 1210 at a position of maximum amplitude to achieve optimized damping. Although shown with a specific arrangement, those of skill in the art will appreciate that other arrangements of partially fixed first elements are possible without departing from the scope of the present disclosure. For example, in one non-limiting embodiment, the fixed portion can be in a more central part of the first element such that the first element has two movable portions (e.g., at opposite ends of the first element). As can be seen in
In the above described embodiments, and in damping systems in accordance with the present disclosure, the first elements are temporarily fixed to the second elements due to a friction contact. However, as vibrations of the downhole systems increase, and exceed a threshold, e.g., when a force of inertia exceeds the static friction force, the first elements (or portions thereof) move relative to the second elements, thus providing the damping. That is, when HFTO increase above predetermined thresholds (e.g., thresholds of amplitude, distance, velocity, and/or acceleration) within the downhole systems, the damping systems will automatically operate, and thus embodiments provided herein include passive damping systems. For example, embodiments include passive damping systems automatically operating without utilizing additional energy and therefore do not utilize an additional energy source.
Turning now to
In some embodiments, the first elements may be substantially uniform in material, shape, and/or geometry along a length thereof. In other embodiments, the first elements may vary in shape and geometry along a length thereof. For example, with reference to
Turning now to
Turning now to
Turning now to
Turning now to
Turning now to
Advantageously, embodiments provided herein are directed to systems for mitigating high-frequency torsional oscillations (HFTO) of downhole systems by application of damping systems that are installed on a rotating string (e.g., drill string). The first elements of the damping systems are, at least partially, frictionally connected to move circumferentially relative to an axis of the string (e.g., frictionally connected to rotate about the axis of the string). In some embodiments, the second elements can be part of a drilling system or bottomhole assembly and does not need to be a separately installed component or weight. The second element, or a part thereof, is connected to the downhole system in a manner that relative movement between the first element and the second element has a relative velocity of zero or close to zero (i.e., no or slow relative movement) if no HFTO exists. However, when HFTO occurs above a distinct acceleration value, the relative movement between the first element and the second element is possible and alternating plus and minus relative velocities are achieved. In some embodiments, the second element can be a mass or weight that is connected to the downhole system. In other embodiments, the second element can be part of the downhole system (e.g., part of a drilling system or BHA) with friction between the first element and the second element, such as the rest of the downhole system providing the functionality described herein.
As described above, the second elements of the damping systems are selected or configured such that when there is no vibration (i.e., HFTO) in the string, the second element will be frictionally connected to the first element by the static friction force. However, when there is vibration (HFTO), the second elements become moving with respect to the first element and the frictional contact between the first and the second element is reduced as described above with respect to
In the various configurations discussed above, sensors can be used to estimate and/or monitor the efficiency and the dissipated energy of a damper. The measurement of displacement, velocity, and/or acceleration near the contact point or surface of the two interacting bodies, for example in combination with force or torque sensors, can be used to estimate the relative movement and calculate the dissipated energy. The force may also be known without a measurement, for example, when the two interacting bodies are engaged by a biasing element, such as a spring element or an actuator. The dissipated energy could also be derived from temperature measurements. Such measurement values may be transmitted to a controller or human operator which may enable adjustment of parameters such as the normal force and/or the static or dynamic friction coefficient(s) to achieve a higher dissipated energy. For example, measured and/or calculated values of displacement, velocity, acceleration, force, and/or temperature may be sent to a controller, such as a micro controller, that has a set of instructions stored to a storage medium, based on which it adjusts and/or controls at least one of the force that engages the two interacting bodies, and/or the static or dynamic friction coefficients. Preferably, the adjusting and/or the controlling is done while the drilling process is ongoing to achieve optimum HFTO damping results.
While embodiments described herein have been described with reference to specific figures, it will be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications will be appreciated to adapt a particular instrument, situation, or material to the teachings of the present disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that the present disclosure will include all embodiments falling within the scope of the appended claims or the following description of possible embodiments.
Severe vibrations in drillstrings and bottomhole assemblies can be caused by cutting forces at the bit or mass imbalances in downhole tools such as drilling motors. Negative effects are among others reduced rate of penetration, reduced quality of measurements and downhole failures.
Different sorts of torsional vibrations exist. In the literature the torsional vibrations are mainly differentiated into stick/slip of the whole drilling system and high-frequency torsional oscillations (HFTO). Both are mainly excited by self-excitation mechanisms that occur due to the interaction of the drill bit and the formation. The main differentiator between stick/slip and HFTO is the frequency and the typical mode shape: In case of HFTO the frequency is above 50 Hz compared to below 1 Hz in case of stick/slip. Further the excited mode shape of stick/slip is the first mode shape of the whole drilling system whereas the mode shape of HFTOs are commonly localized to a small portion of the drilling system and have comparably high amplitudes at the bit.
Due to the high frequency HFTO corresponds to high acceleration and torque values along the BHA and can have damaging effects on electronics and mechanical parts. Based on the theory of self-excitation increased damping can mitigate HFTOs if a certain limit of the damping value is reached (since self-excitation is an instability and can be interpreted as a negative damping of the associated mode).
One damping concept is based on friction. Friction between two parts in the BHA or drill string can dissipate energy and reduce the level of torsional oscillations.
In this idea a design principle is discussed that to the opinion of the inventors works best for damping with friction. The damping shall be achieved by a friction force where the operating point of the friction force with respect to the relative velocity has to be around point 204 shown in
As discussed above, friction forces between the drilling system and the borehole will not generate significant additional damping in the system. This is because the relative velocity between the contact surfaces (e.g. a stabilizer and the borehole) does not have a zero mean value. The two interacting bodies of the friction damper must have a mean velocity or rotary speed relative to each other that is small enough so that the HFTO leads to a sign change of the relative velocity of the two interacting bodies of the friction damper. In other words, the maximum of the relative velocities between the two interacting bodies generated by the HFTO needs to be higher than the mean relative velocity between the two interacting bodies.
Energy dissipation only occurs in a slipping phase via the interface between the damping device and the drilling system. Slipping occurs if the inertial force exceeds the limit between sticking and slipping that is the static friction force: FR>μ0·FN (wherein the static friction force equals the static friction coefficient multiplied by the normal force between both contacting surfaces). The normal force and/or the static or dynamic friction coefficient may be adjustable to achieve an optimal or desired energy dissipation. Adjusting at least one of the normal force and the static or dynamic friction coefficient may lead to an improved energy dissipation by the damping system.
As discussed herein, the placement of the friction damper should be in the area of high HFTO accelerations, loads, and/or relative movement. Because different modes can be affected a design is preferred that is able to mitigate all HFTO modes (e.g.,
An equivalent can be used as a friction damper tool of the present disclosure. A collar with slots as shown in
The advantage of this principle is that the friction devices will be directly mounted into the force flow. A twisting of the collar due to an excited HFTO mode and corresponding mode shape will partly be supported by the friction devices that will move up and down during one period of vibration. The high relative movement along with an optimized friction coefficient and normal force will lead to a high dissipation of energy.
This goal is to prevent an amplitude increase of the HFTO amplitudes (represented by tangential acceleration amplitudes in this case). The (modal) damping that has to be added to every instable torsional mode by the friction damper system needs to be higher than the energy input into the system. The energy input is not happening instantaneously but over many periods until the worst case amplitude is reached (zero RPM at the bit).
With this concept a comparably short collar can be used because the friction damper uses the relative movement along the distance from bit. It is not necessary to have a high tangential acceleration amplitude but only some deflection (“twisting”) of the collar that will be achieved in nearly every place along the BHA. The collar and the dampers should have a similar mass to stiffness ratio (“impedance”) compared to the BHA. This would allow the mode shape to propagate in the friction collar. A high damping will be achieved that will mitigate HFTO if the parameters discussed above are adjusted (normal force due to springs etc.). The advantage in comparison to other friction damper principles is the application of the friction devices directly into the force flow of the deflection to a HFTO mode. The comparably high relative velocity between the friction devices and the collar will lead to a high dissipation of energy.
The damper will have a high benefit and will work for different applications. HFTO causes high costs due to high repair and maintenance efforts, reliability issues with non-productive time and small market share. The proposed friction damper would work below a motor (that decouples HFTO) and also above a motor. It could be mounted in every place of the BHA that would also include a placement above the BHA if the mode shape propagates to this point. The mode shape will propagate through the whole BHA if the mass and stiffness distribution is relatively similar. An optimal placement could for example be determined by a torsional oscillation advisor that allows a calculation of critical HFTO-modes and corresponding mode shapes.
A resource exploration and recovery system, in accordance with an exemplary embodiment, is indicated generally at 3010, in
Second system 3018 may include a tubular string 3030, formed from one or more tubulars 3032, which extends into a borehole or wellbore 3034 formed in formation 3036. Wellbore 3034 includes an annular wall 3038 which may be defined by a surface of formation 3036. In an embodiment, tubular string 3030 takes the form of a drill string (not separately labeled that supports a bottom hole assembly (BHA) 3044 which, in turn, is connected to a drill bit 3048 that is operated to form wellbore 3034. That is, BHA 3044 includes drill bit 3048 as well as drill collars and other components (not separately labeled). BHA 3044 may include a rotary steerable tool, a drilling motor, sensing tools, such as a resistivity measurement tool, a gamma measurement tool, a density measurement tool, a directional measurement tool, stabilizer, and a power and/or communication tool. In accordance with an exemplary embodiment, a vibration isolation device 3050 is mechanically connected above, below, or between components of BHA 3044. Vibration isolation device 3050 is a modular tool that can be installed at various positions above, below, or within BHA 3044. For example, vibration solation device 3050 can be installed above a steering unit (not shown) and below one or more formation evaluation tools. Vibration isolation device 3050 defines a flexible connection that limits vibrations, for example, high frequency torsional oscillations (HFTO) that may result from drill bit 3048 passing through components of second system 3018 toward surface system 3016.
Reference will now follow to
In accordance with an exemplary embodiment, support element 3060 includes a first end portion 3068, a second end portion 3069 and an intermediate portion 3071 extending therebetween. First end portion 3068 may be connected to other components of the BHA 3044 and second system 3018, for example by a thread. Intermediate portion 3071 includes an inner wall (not separately labeled) that defines an internal portion 3074. A blocking element 3080 is arranged proximate to first end portion 3068 within internal portion 3074. Blocking element 3080 prevents relative rotation between support member 3060 and drill bit 3048 in at least one direction. In one exemplary embodiment, blocking element 3080 is fixedly attached to support member 3060. Fixed attachment of blocking element 3080 to support member 3060 may be achieved by screws, clamps, welding, adhesive attachment, or similar means. Blocking element 3080 may include a mud flow passage 3082 that permits a flow of, for example, drilling mud to enter internal portion 3074. Support element 3060 may be formed from, for example, steel or alloys thereof.
In further accordance with an exemplary embodiment, torsional flexible element 3064 includes a first end 3090, and a second end 3091. First end 3090 defines a shaft 3094 having a first end section 3095 and a second end section 3096. Shaft 3094 is formed from a material and/or shape that is more flexible than support element 3060. A parameter of the torsional flexibility of the torsional flexible element 3064 is the torsional spring constant (also known as spring's torsion coefficient, torsion elastic modulus, or spring constant) of the torsional flexible element 3064. For example, shaft 3094 may be formed from titanium, titanium alloys brass, aluminum, aluminum alloys, nickel alloys, steel, such as high strength steel, alloys of steel, a composite, or carbon fiber. Material of shaft 3094 may be selected by its shear modulus which affects the spring constant of shaft 3094. Material of shaft 3094 may also be selected by its density which is related to the mass or moment of inertia of shaft 3094 which also affects the isolation efficiency of shaft 3094. A lower mass or moment of inertia, and thus, a lower density of shaft 3094 increases the isolation efficiency of shaft 3094. More specifically, torsional flexible element 3064 and/or shaft 3094 is formed from a material, and is sized and shaped to provide a selected flexibility that promotes relative angular rotation relative to support element 3060 in order to isolate predetermined vibrations resulting from HFTO.
Thus, in an embodiment, vibration isolation device 3050 is designed to possess a torsional flexibility per unit length that is greater than a torsional flexibility per unit length of at least a portion of the BHA. For example, in an embodiment, vibration isolation device 3050 is designed to possess a torsional flexibility per unit length or that is greater than a torsional flexibility per unit length of support element 3060 or a component above support element 3060. An effective isolation may be achieved if the torsional spring constant of the torsional flexible element 3064 is lower than other components in the BHA 3044 or vibration isolation device 3050. For example, an effective isolation may be achieved if the torsional spring constant of the torsional flexible element 3064 is at least 10 times lower than other components in the BHA 3044 or vibration isolation device 3050 (e.g. support element 3060). For example, an effective isolation may be achieved if the torsional spring constant of the torsional flexible element 3064 is at least 50 times lower than other components in the BI-IA 3044 or vibration isolation device 3050 (e.g. support element 3060). In order to create such a torsional flexible portion the moment of inertia can be reduced, the length of the torsional flexible portion can be increased, and/or a material with a lower shear modulus can be selected. For a cylindrical torsional flexible element 3064 with a material that has a given shear modulus, the second moment of area can be decreased or the length can be increased to decrease torsional spring constant.
In the embodiment of
In still further accordance with an exemplary embodiment, a first radial bearing 3130 is arranged between drill bit 3048 and support element 3060. For example, in an exemplary embodiment, a first radial bearing 3130 is arranged between coupler 3108 and support element 3060. A second radial bearing 3131 is arranged between drill bit 3048 and support element 3060, such as between coupler 3108 and support element 3060 axially spaced apart from first radial bearing 3130. At this point, it should be understood that the term “radial bearing” describes a bearing that supports angular rotation and axial movement while at the same time limit radial movement. The term “axial bearing” describes a bearing that supports angular rotation and radial movement while at the same time limits axial movement. It should also be understood that the number and position of bearings between drill bit 3048 and support element 3060 along vibration isolation device 30503064 may vary. Further, one or more axial load transferring elements, such as axial bearings or thrust bearings 3134 may be arranged between support element 3060 and drill bit 3048, such as between coupler 3108 and support element 3060. Bearings, such as axial bearings 3134 or radial bearings 3130, 3131, may comprising coatings or inserts such as diamond inserts (e.g. polycrystalline diamond compact (PDC) inserts) that protect bearing parts from damage or wear. The bearings may be ball bearings, thrust ball bearings, or roller bearings. Bearings may be installed in a bearing seat (not shown) that is movable with respect to support element 3060. For example bearings may be installed in a bearing seat that is pivotable with respect to support element 3060. In the arrangement of
In accordance with an exemplary aspect, differential movement between support element 3060 and torsional flexible element 3064 dissipates energy through friction thereby dampening modal deformation. That is, energy that may be imparted to support element 3060 and/or torsional flexible element 3064 is dampened through frictional forces. More specifically, radial bearings 3130, 3131, and/or one or more axial bearings 3134 may define a friction damper (not separately labeled). In addition, to bearings 3130, 3131, and 3134, separate damping elements (not shown) may be included in the vibration isolation device 3050 such as damping elements discussed and disclosed with respect to
It should be understood that an adjustment device 3200 may be connected to first radial bearing 3130, second radial bearing 3131 and/or one or more axial bearings 3134. Adjustment device 3200 may selectively adjust frictional forces in first radial bearing and/or second radial bearing 3131 as well as in one or more axial bearings 3134. Adjustment device 3200 may include passive devices such as springs, and or active devices such as actuators, controlled dampers and the like. A measurement device 3210 may be employed to measure an amount of damping. Measurement device 3210 may be connected to adjustment device 3200 through a controller 3220. Controller 3220 may control an amount of damping provided through adjustment device 3200 based on parameters sensed by measurement device 3210 or as sensed by other BHA components.
During the drilling process, support element 3060 may be rotated by a rotating device (not shown) which may be part of the BHA 3044 (e.g. by a drilling motor) or located at the surface as part of the first system 3014 (e.g. by a so called top drive located at the earth's surface). The torque of rotating support element 3060 is transferred to the drill bit 3048 via torsional flexible element 3064, shaft 3094 and coupler 3108. By rotating drill bit 3048, drill bit 3048 interacts with formation 3036 that may in turn create torsional oscillations at the drill bit 3048 which will overlay the rotation of drill bit 3048 by rotating support element 3060. The torsional oscillations may be transferred through the various components of second system 3018 depending on their mass, moment of inertia, spring constant, or flexibility per unit length.
For example, the amount of torsional oscillations that is transferred through shaft 3094 is lower than through another component of second system 3018 if the flexibility per unit length of shaft 3094 is higher than the flexibility per unit length of the other component of second system 3018. In addition, the amount of torsional oscillations that is transferred through bearings such as radial bearings 3130, 3131, or one or more axial bearings 3134 is also very low compared to other components of the second system 3018. Hence, by the configuration shown in
For example, in an exemplary embodiment, torsional flexible element 3064 or shaft 3094 transfer torque as well as axial load from and to the drill bit 3048. In another exemplary embodiment, torsional flexible element 3064 or shaft 3094 may only transfer torque from and to the drill bit 3048 and other loads, such as axial loads and/or bending (e.g. cyclic bending), may be transferred by one or more axial bearings 3134 and/or radial bearings 3130, 3131, respectively. In another exemplary embodiment, support element 3060 transfers bending moment and axial loads partially via radial bearings 3130, 3131 and one or more axial bearings 3134 from and to drill bit 3048. By utilizing axial bearing 3134 and radial bearings 3131, 3130 below the second end section 3096 of shaft 3094, support element 3060 and drill bit 3048 are rotationally decoupled for small torsional deflections or oscillations. In other words, at least a part of the torque and torsional oscillations are transferred between drill bit 3048 and support element 3060 via torsional flexible element 3064 and shaft 3094. Thus, in one non-limiting embodiment, torsional flexible element 3064 or shaft 3094 transfer 30% or more of the torque from and to the drill bit 3048.
For example, in one non-limiting embodiment, torsional flexible element 3064 or shaft 3094 transfer 60% or more of the torque from and to the drill bit 3048. For example, in one non-limiting embodiment, torsional flexible element 3064 or shaft 3094 transfer 90% or more of the torque from and to the drill bit 3048. In a similar way, axial bearing 3134 may transfer 30% or more of the axial load from and to the drill bit 3048. For example, axial bearing 3134 may transfer 60% or more of the axial load from and to the drill bit 3048. For example, axial bearing 3134 may transfer 90% or more of the axial load from and to the drill bit 3048.
It should be understood, that comparably large deflections may take place at the torsional flexible element 3064. Looking further into
In accordance with an exemplary embodiment, vibration isolation device 3050 absorbs vibrations that may result from HFTO produced by drill bit 3048. That is, torsional flexible element 3064 may oscillate angularly relative to support element 3060 to isolate vibrations. Without the incorporation of vibration isolation device 3050 torsional vibrations may occur at multiple frequencies having multiple modes along BHA 3044 as shown at 3148 in
As shown in
For example, amplitudes above vibration isolation device 3050 may be 40% lower than below vibration isolation device 3050. For example, amplitudes above vibration isolation device 3050 may be 60% lower than below vibration isolation device 3050. For example, amplitudes above vibration isolation device 3050 may be 85% lower than below vibration isolation device 3050. By comparing
For example, a vibration isolation device can be described as an oscillator, such as a torsional oscillator with a spring constant, such as a torsional spring constant, which acts as a mechanical low pass filter comprising an isolation frequency or cut-off frequency. Frequencies above that cut-off frequency are partially or completely suppressed and therefore isolated from a portion of the BHA 3044. The cut-off frequency (as well as the so-called eigenfrequency or resonance frequency) is a function of the spring constant. The more flexible the torsional oscillator, the lower the cut off frequency. For a cylindrical vibration isolation device, the cut-off frequency also depends on the length and the diameter of the vibration isolation device. Typical cylindrical vibration isolation device may have a diameter of less than 15 cm depending on material and the tool size. For example, a typical cylindrical vibration isolation device may have a diameter of less than 15 cm in 9.5″ tools and less than 8 cm in 4.75″ tools. For example, a typical cylindrical vibration isolation device may have a diameter of less than 13 cm in 9.5″ tools and less than 7 cm in 4.75″ tools. Similar, typical lengths of a vibration isolation device may be above 0.75 m depending on the tool size. For example, typical lengths of a cylindrical vibration isolation device may be above 0.75 m in 4.75″ tools and above 0.8 m in 9.5″ tools. For example, typical lengths of a cylindrical vibration isolation device may be above 0.9 m in 4.75″ tools and above 1.1 m in 9.5″ tools.
As shown in
It should be understood that instead or in addition to the bearing elements other friction dampener components (not displayed) can be connected to the coupler 3108 and the support element 3060 in a similar fashion as the bearing elements, with the difference that those other components are not utilized as bearing elements but for friction damping purposes. Those friction dampener components can be sized in an optimum manner for dampening. The material of those friction dampener components can also be selected accordingly. Those additional friction dampener components also take advantage of the relatively high modal deformation.
In yet still further accordance with exemplary embodiment, an electrical conduit, such as an electrical conductor 3137, wire, or cable may extend through vibration isolation device 3050 for transmission of electrical power and/or communication through vibration isolation device 3050. Electrical conductor 3137 may, for example, extend through support element 3060 and transition into torsional flexible element 3064 via shaft 3094. Electrical conductor 3137 may extend to a connector portion 3140 provided on coupler 3108. Connector portion 3140 may take the form of an electrical contact such as a contact ring, a sliding contact, an inductive connection, or a resonant electromagnetic coupling device 3142. It should be understood that other connector types are also possible. For example, connector portion 3140 may also take the form of a centrally positioned pin type connector. In accordance with an exemplary embodiment, vibration isolation device 3050 absorbs vibrations that may result from HFTO produced by drill bit 3048. That is, torsional flexible element 3064 may rotate angularly relative to support element 3060 to absorb vibrations. Without the incorporation of vibration isolation device 3050 vibrations may occur at multiple frequencies having multiple modes as shown at 3148 in
Reference will now follow to
First recess 3318 includes a first stop surface 3322 and a second stop surface 3323. Second stop surface 3323 is spaced circumferentially relative to first stop surface 3322. Similarly, second recess 3320 includes a third stop surface 3326 and a fourth stop surface 3327. Fourth stop surface 3327 is spaced circumferentially from third stop surface 3326. First, second, third, and fourth stop surface extend radially outwardly of inner surface 3310.
In still further accordance with an exemplary aspect, coupler 3108 includes a first lobe section 3340 defined by, at least a portion of, outer surface 3312. Coupler 3108 also includes a second lobe section 3342 that is arranged opposite of first lobe section 3340. The number of lobe sections and the relative location of the lobe sections may vary. Typically, the number and location of the lobe sections would correspond to the number and orientation of the recesses formed in inner surface 3310.
First lobe section 3340 includes a first stop surface section 3346 and a second stop surface section 3348. First stop surface section 3346 is substantially complimentary of first stop surface 3322 and second stop surface section 3347 is substantially complimentary of second stop surface 3323. Second lobe section 3342 includes a third stop surface section 3350 and a fourth stop surface section 3352. Third stop surface section 3350 is substantially complimentary of third stop surface 3326 and fourth stop surface section 3352 is substantially complimentary of second stop surface 3327. With this arrangement, if for example, drill bit 3048 sticks for any reason, and support member 3060 is be rotated by a surface drive or drilling motor, torsional flexible element 3064 and shaft 3094 could be twisted which may lead to over torque and damage. Stop mechanism 3300 protects torsional flexible element 3064 and shaft 3094 from over torque that may be causes by a stuck or stalled drill bit. Stop mechanism 3300 mechanism may include spring elements or coatings (not shown) that protect the stop surfaces and/or stop surface sections.
Reference will now follow to
In accordance with an exemplary aspect, vibration isolation device 3050 includes an end stop mechanism that limits the relative rotation of hub 4120 with respect to support element 3060. For example, hub 4120 includes a first flange portion 4140 and a second, opposing flange portion 4142. Inner surface 4130 includes a first flange element 4150 and a second opposing flange element 4152. First flange element 4150 may be substantially complimentary of first flange 4140 and second flange element 4152 may be substantially complimentary of second flange 4142. A first spring element 4160 may be arranged between and connected with each of first flange 4140 and first flange element 4150. A second spring element 4162 may also be arranged between and connected with second flange element 4152. First and second spring elements 4160 and 4162 isolate torsional deflection of connector portion 3140 such as may result from vibrations caused by HFTO produced by drill bit 3048.
At this point it should be appreciated that the exemplary embodiments describe a vibration isolating device that isolates or substantially attenuates vibrations produced as a result of high frequency torsional vibrations of a bottom hole assembly (BHA) from other portions of a drill string. The vibration isolation device is designed to possess a torsional flexibility per unit length that is greater than a torsional flexibility of the BHA. In this manner, a torsional flexible element may angularly rotate relative to a support member as a result of torsional vibrations.
Set forth below are some embodiments of the foregoing disclosure.
A device for transferring torque to a drill bit in a borehole having a borehole axis, comprising: a support element configured to rotate in the borehole about the borehole axis; a torque transferring element configured to transfer torque from the support element to the drill bit and further configured to isolate torsional oscillations that are created at the drill bit from the support element; a blocking element configured to block rotation of the torque transferring element relative to the support element about the borehole axis in at least one direction; and a bearing element between the support element and the drill bit.
The device according to any previous embodiment, further comprising an electrical conduit providing power and/or communication from the support element and through at least a part of the torque transferring element.
The device according to any previous embodiment, further comprising an axial load transferring element configured to transfer axial load from the support element to the drill bit.
The device according to any previous embodiment, wherein the axial load transferring element is an axial bearing.
The device according to any previous embodiment, wherein the torque transferring element has a higher flexibility per unit length than the support element.
The device according to any previous embodiment, wherein a torsional spring constant of the torque transferring element is at least 10 times lower than a torsional spring constant of the support element.
The device according to any previous embodiment, wherein the bearing element comprises a radial bearing and/or an axial bearing.
The device according to any previous embodiment, further comprising a damping system configured to damp torsional oscillations in the torque transferring element.
The device according to any previous embodiment, the damping system comprising: a first element; and a second element in frictional contact with the first element, wherein the second element moves relative to the first element with a velocity that is a sum of a periodic torsional oscillations having an amplitude and a mean velocity, wherein the mean velocity is lower than the amplitude of the torsional oscillations.
The device according to any previous embodiment, the damping system comprising: a first element; a second element in frictional contact with the first element; and an adjusting element arranged to adjust a force between the first element and the second element.
The device according to any previous embodiment, further comprising a drilling fluid flowing through the support element and around the torque transferring element.
The device according to any previous embodiment, wherein the device further comprises an end stop that limits rotational movement between the support element and the drill bit.
The device according to any previous embodiment, further comprising a drilling fluid flowing through the bearing element.
A method of transferring torque to a drill bit in a borehole having a borehole axis, the method comprising rotating a support element about the borehole axis; transferring, with a torque transferring element, torque from the support element to the drill bit; isolating with a torsional flexible element torsional oscillations that are created at the drill bit from the support element; blocking, with a blocking element, rotation of the torque transferring element relative to the support element about the borehole axis in at least one direction; and bearing, with a bearing element, the torque transferring element.
The method according to any previous embodiment, further comprising transmitting, with an electrical conduit, power and/or communication signals from the support element and through at least a part of the torque transferring element.
The method according to any previous embodiment, further comprising transferring, with an axial load transferring element, axial load from the support element to the drill bit.
The method according to any previous embodiment, wherein the torque transferring element has a higher flexibility per unit length than the support element.
The method according to any previous embodiment, wherein a torsional spring constant of the torque transferring element is at least 10 times lower than a torsional spring constant of the support element.
The method according to any previous embodiment, further comprising: damping with a damping system torsional oscillations in the torque transferring element.
A system for drilling a borehole into the earth's subsurface, the system comprising: a drill bit configured to rotate and penetrate through the earth's subsurface; and a vibration isolation device configured to isolate vibration that is caused at the drill bit, the vibration having an amplitude, wherein the amplitude of the vibration below the vibration isolation device is 20% higher than the amplitude of the vibration above the vibration isolation device.
The system according to any previous embodiment, wherein the amplitude of the vibration below the vibration isolation device is 50% higher than the amplitude of the vibration above the vibration isolation device.
The system according to any previous embodiment, wherein the amplitude of the vibration below the vibration isolation device is 70% higher than the amplitude of the vibration above the vibration isolation device.
In support of the teachings herein, various analysis components may be used including a digital and/or an analog system. For example, controllers, computer processing systems, and/or geo-steering systems as provided herein and/or used with embodiments described herein may include digital and/or analog systems. The systems may have components such as processors, storage media, memory, inputs, outputs, communications links (e.g., wired, wireless, optical, or other), user interfaces, software programs, signal processors (e.g., digital or analog) and other such components (e.g., such as resistors, capacitors, inductors, and others) to provide for operation and analyses of the apparatus and methods disclosed herein in any of several manners well-appreciated in the art. It is considered that these teachings may be, but need not be, implemented in conjunction with a set of computer executable instructions stored on a non-transitory computer readable medium, including memory (e.g., ROMs, RAMs), optical (e.g., CD-ROMs), or magnetic (e.g., disks, hard drives), or any other type that when executed causes a computer to implement the methods and/or processes described herein. These instructions may provide for equipment operation, control, data collection, analysis and other functions deemed relevant by a system designer, owner, user, or other such personnel, in addition to the functions described in this disclosure. Processed data, such as a result of an implemented method, may be transmitted as a signal via a processor output interface to a signal receiving device. The signal receiving device may be a display monitor or printer for presenting the result to a user. Alternatively, or in addition, the signal receiving device may be memory or a storage medium. It will be appreciated that storing the result in memory or the storage medium may transform the memory or storage medium into a new state (i.e., containing the result) from a prior state (i.e., not containing the result). Further, in some embodiments, an alert signal may be transmitted from the processor to a user interface if the result exceeds a threshold value.
Furthermore, various other components may be included and called upon for providing for aspects of the teachings herein. For example, a sensor, transmitter, receiver, transceiver, antenna, controller, optical unit, electrical unit, and/or electromechanical unit may be included in support of the various aspects discussed herein or in support of other functions beyond this disclosure.
The use of the terms “above”/“below”, “up”/“down”, “upwards”/“downwards” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to mean “closer to the drill bit”/“farther from the drill bit”, respectively, along the second system 3018. The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity).
It will be recognized that the various components or technologies may provide certain necessary or beneficial functionality or features. Accordingly, these functions and features as may be needed in support of the appended claims and variations thereof, are recognized as being inherently included as a part of the teachings herein and a part of the present disclosure.
The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a borehole, and/or equipment in the borehole, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc.
While embodiments described herein have been described with reference to various embodiments, it will be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications will be appreciated to adapt a particular instrument, situation, or material to the teachings of the present disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed as the best mode contemplated for carrying the described features, but that the present disclosure will include all embodiments falling within the scope of the appended claims.
Accordingly, embodiments of the present disclosure are not to be seen as limited by the foregoing description, but are only limited by the scope of the appended claims.
This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 62/643,385 and No. 62/643,291, both filed Mar. 15, 2018, the entire disclosures of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62643385 | Mar 2018 | US | |
| 62643291 | Mar 2018 | US |
