Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses added emphasis has been placed on maximizing each given well's life and productivity over the course of the well's life. Thus, well logging, profiling and monitoring of well conditions are playing an ever increasing role in oilfield operations. Similarly, more actively interventional applications are regularly called for such as clean-out applications, opening or closing valves and sliding sleeves or any number of other maneuvers targeting maximized recovery and well life.
In addition to regular intervention for sake of monitoring and/or managing well operations, the well itself may also be of fairly sophisticated architecture. For example, in an attempt to maximize recovery from the reservoir and extend the useful life of the well, it may be of a fairly extensive depth and tortuous configuration. This may include overall depths in the tens of thousands of feet range. Once more, such wells may include extended horizontal or deviated sections of several thousand feet. As a result, interventions through such wells are becoming of ever increasing difficulty as noted below.
Where interventional applications are sought in wells of particularly challenging architecture, wireline cable, coiled tubing, drill pipe or other semi-rigid conveyance line may be utilized to deliver an interventional tool to a target location in the well. In order to help the conveyance line navigate the well downhole, conveyance aids are available to help the conveyance line and toolstring traverse the challenging architecture of the well. These may include active conveyance aids such as tractors or vibration tools, generally located near the end of conveyance line near the toolstring. Thus, the conveyance line may be actively pulled further downhole or vibrated in such a manner as to help extend the overall reach of the conveyance line.
In light of the potential drawbacks to conveyance aids noted above, a toolstring may be outfitted with more straight-forward, passive features to help in traversing a well of sophisticated architecture. For example, the toolstirng or a housing of a given tool may be equipped with passive rollers. That is, conventional, appropriate sized wheel-like features may be placed at the outer surface of the toolstring. So, for example, where a 100 foot toolstring is rounding a transition bend of a few hundred feet or so into a deviated well section, the rollers may passively contact the well wall as the bend is rounded. This may prevent mechanical or even differential sticking in such situations. Once more, preventing such sticking in this manner may be the extent of the conveyance aid that is required in order to allow the tool to reach the target location downhole. That is, the challenge in delivering the toolstring to the downhole target location at times may be less about overall load capacity throughout the well, for example, as may be met by a heavy duty tractor, and more about being able to passively round a bend at a given location. Certainly where this is the case, passive roller-aided conveyance may be preferable to other aiding techniques.
Unfortunately, while passive roller-aided conveyance may be suitable for helping the toolstring to reach a downhole target location in theory, rollers face their own inherent limitations. For example, passive, and even active rollers, generally include bearing ring assemblies similar to those found in wheels on conventional pair of roller skates. Setting aside manufacturability disadvantages, these types of assemblies are also relatively short-lived upon exposure to downhole environments. That is, it is understandable that a host of spherical bearings exposed to debris, sand or downhole fluids tends to lock-up and/or corrode fairly quickly. Indeed, after every couple of deployments into the well, it is likely that replacement of all of the bearing assemblies for the toolstring is called for. Yet, in spite of these added maintenance and materials costs, this is often the operators' most practical option for aiding in the conveyance of the toolstring.
A downhole toolstring is provided that includes a tool housing equipped with a conveyance aid. The conveyance aid includes at least two roller devices for contacting a wall of the well during the conveyance therethrough. Further, the roller devices themselves each include a cylindrical bearing based mechanism to allow rolling thereof during the contacting of the wall.
Embodiments are described with reference to certain downhole applications through deviated well sections that may benefit from roller devices as an aid to conveyance of a toolstring through the well. In particular, coiled tubing line is utilized to deliver a logging and treatment assembly of considerable length to a downhole location at a depth beyond a non-vertical section of the well. Though, wireline, drill pipe and other conveyance line types may be utilized. Regardless, conveyance of the assembly may be aided by passive rollers thereof as it enters a deviated or tortuous portion of the non-vertical well section. Of course, a host of other downhole assemblies and accessories, conveyed by coiled tubing or otherwise, may be outfitted with conveyance aids as detailed herein. These may include more interventional devices and applications such as for perforating or those of a more passive nature such as for more limited conventional logging. Regardless, so long as the conveyance aid of the assembly includes roller devices with cylindrical bearing based mechanisms therein, enhanced conveyance thereof through the well may be achieved.
Referring now to
Thus, in the depicted example, where the toolstring 101 is conveyed to sufficient depths, it must traverse a bend 197 in the well 180. Given that the toolstring 101 may be a fairly rigid structure spanning 50-150 feet or more, roller device or devices 100 such as those depicted may serve as a passive aid in allowing the toolstirng 101 to round the bend 197. That is, as the rigid toolstring 101 is advanced by conveyance line such as, but not limited to, coiled tubing 110 into the bend 197, the well wall 185 may present a tight fit or squeeze to the elongated toolstring 101. However, the roller devices 100 may passively and responsively roll against the well wall 185 at this time to further aid in conveyance of the toolstring 101 beyond the bend 197.
While rounding the bend 197 with passive assistance of roller devices 100 appears fairly straight forward, particular challenges may be presented to the effectiveness of the devices 100 due to the nature of the well environment. For example, as detailed further below, the toolstring 101 of the example embodiment shown includes logging devices 160 for obtaining a variety of different types of well data such as the nature of the surrounding formation 195 or well fluids and other constituents. Indeed, as shown in
Continuing now with reference to
Continuing with reference to
In the embodiment of
In light of the vast amount of particle and other expected downhole exposures, the roller devices 100 are configured with cylindrical bearing based mechanisms as noted above. More specifically, with reference to
The internals of the roller devices 100 reveal cylindrical bearing based mechanisms in the form of journal bearings 200. That is, the indicated housing 260 is equipped with mandrels 215 that extend therefrom such that circumferential, substantially monolithic journal bearings 200 may be disposed thereabout. In this manner, a smooth substantially uninterrupted bearing interface is provided between the body of each roller device 100 and each mandrel 215. As a result, exposure and opportunity for particulate, sand and other debris 199 of the well 180, to interact with such bearing based mechanisms 200 is kept at a minimum. For example, the amount of exposed surface to volume area is minimized with use of a smooth monolithic piece as opposed to conventional ball bearings. Furthermore, the ability is now afforded to configure the underside of a body of the roller device 100 to substantially morphologically match the journal bearing 200. Thus, the bearing 200 may be substantially isolated from the indicated exposures of concern.
Continuing with reference to
In the embodiment shown, two rollers 100 in an adjacent fashion. Thus, when a sampling implement 265 as shown in
In the embodiment of
Referring now to
With added reference to
Referring now to
The intentional physical disconnect between the journal pieces 320, 340 as described above results in an interface 330 that allows for intentional slippage. That is, the reason forces from one surface 301 or another 315 do not necessarily fully translate across the entirety of the bearing 200 is due to the allowance of slippage at the noted interface 330. Once more, this interface 330 is located at an isolated interior of the bearing 200 such that its presence does not result in a new location of exposure in terms of well debris and other corrosives of the environment. More specifically, unlike use of multi-piece spherical bearings for example, a multi-piece bearing 200 is provided in
Referring now to
Specifically, with reference to
By the same token, with reference to
Additionally, with reference to these same roller devices 401, they may be positioned at opposite sides of the housing 460 and of sufficient distance (d′) relative a diameter (D) of the well 180 so as to provide a degree of centralization. That is, rather than attain a footing at a side of the well 180 opposite the perpendicular axis 411 and zone 466 for the sampling tool 465, centralization above the ‘floor’ of the well wall 485 may be attained. So, for example, at the time of sampling, it is less likely that the elongated interior roller devices 400 would be in contact with debris at the well wall 185, particularly during formation sampling. Of course, a variety of additional tool configurations and roller device types may also be developed which take advantage of underlying embodiments of cylindrical bearing based mechanisms.
Referring now to
Embodiments described hereinabove include roller-aided conveyance devices and techniques that may or may not be passive in nature. However, these roller devices avoid the use of ring assemblies utilizing a plurality of spherical bearings. Thus, bearing life is not significantly compromised in light of regular exposure to the downhole environment. Rather, roller devices and conveyance may be aided through use of an underlying cylindrical bearing based mechanism, that may even be of enhanced manufacturability and comparatively low labor replacement cost. In addition to aiding conveyance of the toolstring 101, those skilled in the art will appreciate that the roller device or devices 100, 400, and/or 401 may also prevent or mitigate sticking of the toolstring 101 while the toolstring 101 is stationary, such as when the sampling implement 265 or sampling tool 465 is directly interfacing with the well wall 185 for extended periods of time, as the roller device or devices 100, 400, and/or 401 may provide a mechanism for passively and/or responsively rolling against a well wall 185 and/or a mudcake formed thereon.
The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. Regardless, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.
This Patent Document claims priority under 35 U.S.C. § 119 to U.S. Provisional App. Ser. No. 61/613,261, entitled “Conveyance Accessories” filed on Mar. 20, 2012, and incorporated herein by reference in its entirety.
Number | Date | Country | |
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61613261 | Mar 2012 | US |