Patent Application
20080060849
This invention and some of its advantages can be better understood by reference to the following detailed description, considered in connection with the accompanying drawings, wherein:
Embodiments of the present invention provide methods and apparatus that may be used to mitigate the effects of vibration of various tools, such as downhole tools, by utilizing a vibration isolation device incorporating a shape memory alloy (SMA) material. For some embodiments, the vibration isolation device, which may be referred to as an SMA “damper”, may be designed and deployed to utilize static loading during expected operation to induce partial phase transformation from austenite to martensite. This partial phase transformation may result in reduced stiffness compared to a tool or component in either the austenite or martensite phase completely.
Accordingly, when the vibration isolation device is subjected to additional loading due to vibrations, the lower stiffness of the SMA material may reduce the force transmissibility between associated coupled components based on the partial phase transformation. That is, energy from the additional loading due to vibrations may be consumed by phase transformation of the SMA material in the vibration isolation device, rather than be transmitted to components.
As used herein, the term shape memory alloy (SMA) generally refers to a metal that exhibits properties generally referred to as the shape memory effect and superelasticity (also known as pseudoelasticity). Various types of SMAs that may be suitable for use as described herein include, but are not limited to NiTi (Nickel-Titanium), CuZnAl (Copper-Zink-Aluminum), NiTiCu (Nickel-Titanium-Copper), and CuAlBe (Copper-Aluminum-Beryllium), or any combination thereof. The particular composition or ratio of each element for any particular alloy may be selected based on the desired properties for a given application.
The shape memory effect refers to the ability of an SMA to return to its original shape after it has been deformed therefrom. In some situations, an SMA may return to its original shape via heating and/or during unloading (from a superelastic state). This effect is due to a temperature-dependent phase transformation between a low-symmetry crystallographic structure (known as martensite) to a high-symmetry crystallographic structure (known as austenite). Further explanation of the underlying physics resulting in the SMA properties is provided in Otsuka et al., Wayman et al. and Funakubo et al. See, e.g., Otsuka, K., and Wayman, C. M. (Eds.), Shape Memory Materials, Cambridge University Press, Cambridge, (1999); Wayman, C. M. Phase Transformations, Nondiffusive, In: Cahn, R. W., Haasen, P. (Eds.), Physical Metallurgy. North-Holland Physics Publishing, New York, pp. 1031-1075, (1983); Funakubo, H. (Ed.), Shape Memory Alloys. Gordon Breach Sci. Pub., New York, (1987).
The temperatures at which the martensite and austenite phases start and finish forming, respectively, may be represented by the following variables: MS, MF, AS, and AF. These temperatures are dependent on the particular composition of the SMA and are typically known and provided by a vendor of the SMA. Superelasticity generally occurs when the SMA is completely composed of material in austenite phase (i.e., at temperature is greater than AF). As the load on the SMA is increased, material in the austenite phase transforms into the martensite phase because of the loading. The temperatures and strain at which the SMA changes its crystallographic structure are characteristic of the particular SMA selected, and can be tuned by varying elemental ratios and/or thermomechanical treatment.
As used herein, the term drill string generally refers to a combination of a drillpipe, a bottomhole assembly (BHA), and any other tools used to make an excavating member (e.g., a drill bit, underreaming device, or other type of device suitable for removing earth formation) rotate or turn at the bottom of the wellbore (e.g., a mud or electric motor). Drillpipe generally refers to tubular elements fitted with special threaded ends to connect rig surface equipment with the bottomhole assembly and the drill bit, allowing drilling fluid to be pumped to the drill bit and allowing the drill bit to be raised, lowered and rotated. Bottom hole assembly generally refers to a lower portion of the drill string including the drill bit, bit sub, a mud motor (in certain applications), stabilizers, drill collars, heavy-weight drillpipe, jarring devices (“jars”), and various other components.
To facilitate understanding the following description refers to a vibration isolation device having SMA materials positioned to reduce vibrations transmitted between a drill bit and a drill string as a specific, but not limiting, example of a useful application. However, those skilled in the art will recognize that a vibration isolation device of the type described herein and/or utilized in the manner described herein may be used to mitigate the effects of vibration in a wide variety of applications involving a wide variety of different tools.
These applications may include various drilling techniques, for example, using casing as the drill string, coiled tubing, as well as applications where there no drill string is used, but rather a bottom hole assembly deployed on wireline, or any other type of rotating member or rotation component. An SMA vibration isolation device as described herein may also be used in an autonomous drilling apparatus, for example, to isolate vibrations transmitted between a drill bit and a remotely operated drive motor or other type equipment (such as logging equipment used to measure downhole parameters while drilling). An SMA vibration isolation device, as described herein, may also be used in other types of applications utilizing rotating members that generate vibrations, such as underreaming, where the diameter of an existing borehole is expanded.
Referring first to
In general, the vibration isolation device 101 may be positioned at any location suitable to dampen vibrations generated when penetrating the Earth with the drill bit 112. As an example, the vibration isolation device 101 may be part of the drill string 120 or threaded in line with the drill string 120 (as shown). As another example, the vibration isolation device 101 may be part of the bottom hole assembly 110, for example, in the form of a drill collar or near-bit component (e.g., located at, near, or between stabilizers 114). Regardless, by placing the vibration isolation device 101 adjacent to or near the bottom hole assembly 110, the vibration isolation device 101 may reduce the amount of vibrations transmitted between the drill string 120 and the bottom hole assembly 110, as well as the vibrations transmitted between the drill bit 112 and the drill string 120.
As described in greater detail below, the vibration isolation device 101 may be designed, such that during the vibration loading or the operating temperature expected during operation, the body 102 undergoes at least a partial phase transformation. Thus, in this exemplary application, the properties of the particular SMA material chosen for use in the body 102, as well as the dimensions of the vibration isolation device 101 (e.g., inner diameter, outer diameter, and length), may depend on a number of factors, such as the expected weight-on-bit and rotational speed of the drill string which may determine the longitudinal strain and rotational strain (torque), respectively. Other factors that may determine the selection of the actual SMA material may include an expected range of temperatures (e.g., expected downhole temperatures) in which the device 101 operates and the materials (e.g., drilling and production fluids) to which the device 101 is exposed.
At least two types of loading may be considered or utilized in the design of the vibration isolation device 101 to mitigate vibrations. The weight-on-bit in the axial direction results in a quasi-static loading, while the string rotation results in constant torque. An additional type of loading is dynamic loading due to axial, lateral and/or torsional vibrations. To enhance vibration isolation, the vibration isolation device 101 may be designed such that, at the expected operating temperature downhole, the force due to static loading is sufficient to induce partial phase transformation of the SMA material from austenite to martensite.
Further, the temperature near the vibration isolation device 101 may also be adjusted to facilitate mitigate of vibrations by adjusting the temperature in the vibration isolation device 101. To adjust the temperature, fluids of different temperatures may be passed through or around the vibration isolation device 101 or an electrical heating/cooling device may be used. The temperature change may result in the SMA operating in a more favorable temperature/strain regime.
As illustrated, the temperatures at which transformation from the martensite phase to austenite phase begins and ends depends on the level of stress applied to the SMA material, as indicated by the martensitic start and finish lines 206 and 208, respectively, which define an austenite-to-martensite transformation region 210. Similarly, the temperatures at which transformation from austenite phase to martensite phase begins and ends also depend on the level of stress, as indicated by the austenitic start and finish lines 204 and 202, respectively, which define a martensite-to-austenite transformation region 220.
As described above, one of the behaviors exhibited by SMA materials is superelasticity. While the material behaves as martensite at temperatures below MF, superelastic behavior is observed during loading and unloading at temperatures above AF. The superelastic behavior is associated with stress-induced martensitic phase transformation and reversal to the austenite phase upon unloading. An example of a superelastic “loading path” 230 as a function of stress in an isothermal example is shown in the phase diagram of
During the loading process, the shape memory alloy behaves in an elastic manner, as shown in the austenite elastic line 302. When a threshold stress level is reached (as indicated by point 303 on the stress axis 350), the transformation stage begins. As the loading continues to increase along an austenite-to-martensite transformation line 304, the transformation strains are generated during conversion of the shape memory alloy from the austenite phase to the martensite phase. When the shape memory alloy has transformed completely into the martensite phase, as shown by the martensite elastic line 306 that begins at point 305 along the stress axis 350, the shape memory alloy behaves in an elastic manner of the martensite phase and continues this behavior as loading is increased until, eventually, permanent deformation occurs. Preferably, the SMA material for the vibration isolation device is selected such that permanent deformation occurs at a point well outside the values of stress and strain expected during normal operation.
During the unloading process, the shape memory alloy again behaves in an elastic manner that is consistent with the martensite phase, as shown in the martensite elastic line 306. When a threshold stress level, such as indicated by point 307 along the stress axis 350, is reached, the reverse transformation stage begins for the conversion from martensite-to-austenite phase, as shown by second transformation line or martensite-to-austenite transformation line 308. As the stress on the shape memory alloy is further reduced, the shape memory alloy may reform into its previous structure. When the shape memory alloy has transformed completely into the austenite phase (past point 309), as shown by the austenite elastic line 302, the shape memory alloy behaves in an elastic manner of the austenite phase.
During a superelastic loading-unloading cycle, a portion of the mechanical energy that is used for phase transformation is converted to heat and dissipated. The dissipated energy is equal to the shaded area 310 inside the stress-strain loop shown in
The outer loop exhibiting hysteresis shown in
As noted above, at least two types of loading components may be considered when designing and/or deploying a vibration isolation device, such as the vibration isolation device 101. The first type of loading component is quasi-static loading, resulting from weight-on-bit in the axial direction and a constant torque due to string rotation. The second type of loading component is dynamic loading due to vibrations, such as axial, lateral and/or torsional vibrations. Accordingly, to enhance the effectiveness of the vibration isolation device, it may be designed such that the force due to static loading is sufficient to induce partial phase transformation between the austenite phase and the martensite phase for the portion of the vibration isolation device made from SMA material.
This partial phase transformation is shown in the diagram 400 of
With the SMA material in the vibration isolation device, its properties give a vibration isolation device an advantage over traditional isolation devices because of the phase transformation. For example, traditional vibration isolation devices utilize spring elements, which have problems with resonant behavior at low frequencies, due to low stiffness of the spring elements. While some traditional vibration isolation devices may include additional damping elements (possibly in an effort to alleviate this problem), these damping elements add cost and complexity and may degrade the response of the vibration isolation devices at higher frequencies.
The vibration isolation device of the present embodiments utilizes the properties of the SMA material to enhance vibration isolation over other techniques. For example, for a fixed value of the acceleration, high frequency dynamic stresses (e.g., due to vibration) may result in low amplitude (small displacement) vibration as shown by minor transformation loops 404. These minor transformation loops 404 introduce very little damping, as indicated by the relatively small area enclosed by the minor transformation loops 404. However, for low frequencies with the same value of acceleration, the amplitude of the vibrations are larger (larger displacement), which result in larger transformation loops 406. These transformation loops 406 provide larger damping from the vibration isolation device. Thus, unlike the response of traditional vibration isolation devices, with SMA vibration isolation devices, larger damping may occur at lower frequencies, which typically correspond to higher amplitudes, while less damping occurs at higher frequencies, which typically correspond to lower amplitudes.
The high and low frequency responses are provided by the inherent properties of the SMA material operating in the superelastic regime. In addition, these effects occur not only during axial loading, but also during bending and torsion of the vibration isolation device. Thus, in addition to axial vibrations, lateral and torsional vibrations may also be reduced by the embodiments of the vibration isolation device.
As a result of the material properties, a vibration isolation device formed with an SMA material may provide adequate response without the use of separate spring and damping elements. For some embodiments, the vibration isolation device may be formed as a relatively simple structure, such as a tubular element in-line with, or as part of, a drill string or bottom hole assembly. Such a simple mechanical structure may be beneficial because it has does not have moving parts, which may enhance reliability.
As described above, enhanced vibration damping may be achieved by operating the vibration isolation device in a superelastic regime (e.g., as close as possible to a major transformation loop). Thus, in some cases, an isolation device may be designed with a particular SMA that exhibits superelasticity under the expected operating conditions (e.g., downhole temperature and weight-on-bit) of the isolation device.
For some embodiments, an SMA vibration isolation device may be combined with conventional vibration isolation devices, such as shock subs. Further, other embodiments may include multiple SMA vibration isolation devices coupled together or distributed along an area to optimize dampening effects. In this manner, the vibration isolation devices may be designed to operate for different loads and placed in different locations based on the expected vibrations during operation. Further, this embodiment may enable the operations, such as drilling operations, to continue for larger distances as the loading and temperatures influence the phase of the SMA material in the vibration isolation devices. Accordingly, the multiple isolation devices may include the same or different material and/or dimensional properties to gain a desired effect. Further, for some embodiments, different SMA materials may be used within the same device and/or SMA materials may be combined with non-SMA materials. That is, each of the vibration isolation devices may be selected to facilitate vibration mitigation for different temperature/strain regimes.
To manufacture a vibration isolation device having SMA material in accordance with embodiments of the present invention, a number of parameters may be considered, as discussed in
The operations begin, at block 502, by determining an expected range of downhole temperatures. The expected range of temperatures may be determined based on historical data (e.g., previously logged) or via simulation and/or modeling. At block 504, a SMA material may be selected that exhibits superelasticity within the expected range of downhole temperatures. The transformation temperatures of a specific SMA may depend on factors, such as chemical composition, heat treatment and/or cold work.
At block 506, an expected range of weight-on-bit and torque values are determined. As with the expected range of temperatures, these values may be determined based on historical data (e.g., previously logged) or via simulation and/or modeling. At block 508, inner and outer dimensions of the SMA isolation device may be calculated based on the expected range of weight-on-bit and torque values. To calculate these dimensions, the operational temperatures, WOB and torque values should be estimated and the stress-temperature phase diagram (e.g., as shown in
At block 510, the length of the isolation device is calculated based on expected ranges of vibration frequency and amplitude. As with the other dimensions, any suitable technique, such as computer modeling and/or simulations may be utilized to calculate the lengths. Due to the potentially high cost of SMA materials, in some cases, blocks 508 and 510 may be performed in an iterative process in an effort to limit the total amount of SMA material used and associated cost.
In blocks 512-516, the design of the vibration isolation device may be fabricated and utilized. At block 512, the design of the vibration isolation device may be stored on a computer. The storage may include writing the design into memory of a computer system, writing the design of the vibration isolation device onto a portable memory, or printing the design of the vibration isolation device. At block, 514, the vibration isolation device may be fabricated based on the stored design. The fabrication may include treating the SMA to achieve desired properties, forming the material to the desired shape and dimensions (e.g., via machining, molding, or any other suitable techniques). At block 516, the vibration isolation device may be utilized in excavating operations to reach a subsurface formation. These operations may include drilling operations, such as drilling a wellbore to access subsurface formation, or other operations, such as under reaming a section of wellbore. Once accessed, the hydrocarbons may be produced from the subsurface formation at block 518.
To make SMA material selection and dimension calculations such that during vibration loading the SMA material undergoes partial phase transformation, detailed numerical and experimental studies for a variety of particular shape memory alloys under consideration may be performed. Such numerical studies may involve building a mathematical model of a drill string and other drilling equipment along with a vibration isolation device. The modeled drill string, drilling equipment and vibration isolation device may then be subjected to vibration loading. In addition, or as an alternative, an actual physical model (e.g., with full-scale or scaled-down dimensions) may be constructed. Regardless, the models may be generated in an effort to accurately represent the response of the SMA material under the anticipated operating conditions.
When designing connectors for the SMA vibration device, it may be desirable that the connectors do not exhibit superelasticity. For example, when designing connectors (such as connectors 104 in
Embodiments of the present invention may be utilized to reduce the adverse effects of vibration, such as that generated by a component or tool in operation. While an SMA vibration isolation device positioned to reduce vibrations transmitted between a drill bit and a drill string has been described in detail above, those skilled in the art will recognize that a vibration isolation device of the type described herein and/or utilized in the manner described herein may be used to mitigate the effects of vibration in a wide variety of applications involving a wide variety of different tools, including, but not limited to, a variety of different type drilling applications and underreaming. With such applications, it may be possible to select a shape memory alloy that exhibits superelasticity as described herein in the expected range of operating conditions.
Further, in another embodiment, the vibration isolation device may be used in operations involving percussion (e.g. hammer) drilling methods. In percussion drilling, the drill string and the drill bit may not rotate because the power or energy is hydraulically or pneumatically supplied to the drill bit. With the percussion drilling, the vibration isolation device may be positioned above the drill bit and used to minimize vibrations transmitted from the drill bit to the drill string and surface equipment during percussion drilling.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims the benefit of U.S. Provisional Application No. 60/844,033, filed Sep. 12, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60844033 | Sep 2006 | US |
