The present disclosure relates generally to useful life improvement for downhole tools and, more specifically, to an ultrasonic impact treatment (“UIT”) to improve the life of downhole tools.
Currently, roller burnishing and shot peening are applied for inner diameter/outer diameter treatment of drill collars and other downhole tools. Each process, however, has its own limitations. For example, the shot peening process is limited by the shallow compressive layer/lower magnitude of induced compressive stress, while roller burnishing (or deep rolling) is limited by the relatively complex nature of the process as well as limited availability in remote drill sites. Moreover, these processes are not suitable for machining tool features having corners or sharp bends, each of which has a direct effect on the useful life of the downhole tool.
Illustrative embodiments and related methodologies are described below as they might be employed in an ultrasonic impact treatment method to improve the useful life of downhole tools. In the interest of clarity, not all features of an actual implementation or methodology are described in this specification. It will be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. Further aspects and advantages of the various embodiments and related methodologies disclosed will become apparent from consideration of the following description and drawings.
As described herein, ultrasonic impact treatment methodologies of the present disclosure can be applied to extend the useful life of downhole tools by inducing compressive stress layers along any desired surface of the downhole tool using an ultrasonic impact treatment device. Through use of the disclosed methods, the useful life of the downhole tool may be improved, such as by increasing the fatigue life, corrosion resistance or weld crack resistance of the downhole tool. Exemplary methodologies achieve the foregoing changes in mechanical properties by introducing ultrasound energy into the surface of the downhole tool through a surface impulse contact probe (pin or ball probe, for example), also known as ultrasonic impact treatment. The ultrasonic impact treatment device introduces deformation on the surface layer which, in turn, induces a compressive residual stress. Since the contact probe can be customized to a desired shape, the ultrasonic impact treatment can be applied to any desired surface of the downhole tool. As the downhole tool is being used, the induced compressive layers prevent crack growth in the tool's subsurface layers, thus increasing its fatigue life, corrosion resistance or weld crack resistance. Accordingly, through use of the disclosed methods, various mechanical/physical properties of the downhole tool may be improved. For example, the fatigue life of a target surface of the downhole tools may be improved by as much as four to five times as compared to an as-machined surface of the downhole tool. With reference to
Referring again to the flowchart of
At block 104, operational parameters of the ultrasonic impact treatment device are then determined based upon the physical characteristics of the downhole tool. Operational parameters may include, for example, device settings and/or physical characteristics of the ultrasonic impact treatment device. Physical characteristics of the ultrasonic impact device may include, for example, the contact probe tip geometry and tip material types. The probe tip geometry and tip material types may be optimized, for example, based upon the physical characteristics and the radii call out on the downhole tool. Similarly, the operational parameters, such as operating frequency and oscillating amplitude, may be optimized based upon the stress analysis performed at the physical characteristics of the downhole tool (e.g. at the corners) and the depth of compressive layers sought to be induced along the downhole tool's surface. The operational parameters may further include, for example, at least one of an operating frequency, oscillating amplitude, treatment travel speed, output power range, or excitation voltage. In certain exemplary embodiments, the operating frequency may be in the range of 20-50 kHz, oscillating amplitude in the range of 20-40 microns, treatment travel speed in the range of 0.3 m/min.-1.5 m/min, output power range of 200-1800 VA, and excitation voltage in the range of 60-110V. However, such operational parameters may be adjusted as necessary for any given application.
At block 106, the ultrasonic impact treatment device is configured to correspond to the operational parameters of the downhole tool. In one implementation, the configuration of the ultrasonic impact treatment device is achieved using one or more user-selectable settings of the ultrasonic impact device, which can be adjusted or otherwise set according to the desired or expected operational parameters necessary for the given downhole tool.
At block 108, the ultrasonic impact treatment device is then used to induce residual compressive stress layers along one or more desired surfaces of the downhole tool, thereby improving the useful life of the downhole tool. In certain implementations, compressive layer depths up to 0.100″ have been imparted on a target surface of a downhole tool according to this aspect of the method. Examples of these target surfaces of the downhole tool that may be treated include the threads, welded portions, or exterior portions of the tool (e.g. external pockets along the tool or corners). Thereafter, the downhole tool treated according to an embodiment of the method outlined in
In certain embodiments, the physical characteristics of the downhole tool described so above may also be used to determine the geometry of the contact probe (alternatively referred to in the art as the indenter) of the ultrasonic impact treatment device, as well as the materials used in the device. The geometry of the ultrasonic impact treatment device may include, for example, the number of contact probes, the contact probe diameter, contact probe tip diameter or treatment angle.
In another example method, the ultrasonic impact treatment may be applied to the downhole tool before, or as step of, repairing the ultrasonic impact treatment device. For example, if a downhole tool has been corroded due to the downhole environment (mud, for example), an ultrasonic impact treatment may first be conducted along the tool's surface according to the presently disclosed principles. After the ultrasonic impact treatment device has been performed, a protective hard-layer coating, such as a high-velocity oxygen fuel spray coating, may be applied. Alternatively, the ultrasonic impact treatment may be conducted on the tool (and then the coating applied) before the tool is ever deployed downhole. In yet another alternative methodology, the entire internal diameter of the downhole tool may be treated using the ultrasonic impact treatment device in order to protect the tool from internal diameter corrosion cracking in those areas experiencing high chloride levels.
As demonstrated above, exemplary methodologies of the present disclosure can be used to impart desired physical or mechanical characteristics to a downhole tool. For example, the fatigue life of the downhole tool is improved when compared to as-machined downhole tools, as can be seen in
In addition, the surface finish is also improved as shown in
Still referring to
In addition, the present disclosure provides a useful effect on the direction of the fatigue crack initiation/propagation.
Moreover, the present disclosure provides portability of application where, for example, a portable ultrasonic impact treatment device may be used offshore or in remote areas (repair and maintenance facilities, for example). As such, the fatigue life of the downhole tool threads or physical characteristics may be improved. In addition, the present disclosure may also be used to combat the cracking susceptibility at the heat affected zones on welded connections along the tool. In such methodologies, the ultrasonic impact treatment is conducted after the welding is completed, thus introducing the compressive layers that combat subsequent cracking.
A few exemplary optimized sets of parameters for specific thread types and/or other physical characteristics will now be described. In one methodology, the ultrasonic impact treatment is applied to the threads of a downhole tool using the following parameters: operating frequency of ˜40 kHz; oscillating amplitude of ˜20 μm; probe tip diameter of ˜0.125″; probe tip radii of ˜0.020″; robotic mode; probe tip hardness of 50 HRC; treatment angle of 45°-90°; measured compressive layer depth of ˜0.012″; and a compressive layer of ˜40-50 ksi.
In another exemplary methodology, the ultrasonic impact treatment is applied to one or more physical characteristics (corners, edges, etc.) using the following parameters: operating frequency of ˜25 kHz; oscillating amplitude of ˜30 μm; probe tip diameter of 0.125″; probe tip radii of ˜0.060″; robotic mode; probe tip hardness of 56 HRC; treatment angle of 45°-90°; measured compressive layer depth of ˜0.070″; and a compressive layer of ˜90-100 ksi. These and a variety of other optimized parameters may be used with the present disclosure.
Although various embodiments and methodologies have been shown and described, the disclosure is not limited to such embodiments and methodologies and will be understood to include all modifications and variations as would be apparent to one skilled in the art. Therefore, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US13/20549 | 1/7/2013 | WO | 00 |