Patent Application
20240141739
The present invention relates to the field of directional drilling, and in particular to a system for repeatedly activating and deactivating tools for use in downhole drilling operations without having to break or trip a tool string.
Downhole drilling operations commonly require a downhole tool to be activated after the tool has been deployed in the borehole. For example, stabilizers are commonly tripped into the borehole in a collapsed state (i.e., with the stabilizer structures retracted into the stabilizer tool body). At some predetermined depth, the stabilizer is activated such that the stabilizer structures expand radially outward from the tool body. Hydraulic activation mechanisms are well known in oilfield services operations and are commonly employed, and even desirable, in such operations.
For example, one well-known hydraulic activation methodology involves dropping an object such as a dart through the interior of the drill string to enable differential hydraulic pressure to activate a downhole tool. Upon completion of the tool's operation, the tool may be deactivated by retrieving the dart using wireline techniques. While commercially serviceable, wireline activation and deactivation is both expensive and time-consuming in that it requires concurrent use of wireline or slickline assemblies.
Another commonly used hydraulic activation methodology makes use of shear pins configured to shear at a specific differential pressure (or in a predetermined range of pressures). Ball drop mechanisms are also known in the art, in which a ball is dropped down through the drill string to a ball seat. Engagement of the ball with the seat typically causes an increase in differential pressure which in turn activates the downhole tool. The tool may be deactivated by increasing the pressure beyond a predetermined threshold such that the ball and ball seat are released (e.g., via the breaking of shear pins). While such shear pin and ball drop mechanisms are also commercially serviceable, they are generally one-time or one-cycle mechanisms (or at least small numbers of cycles) and do not typically allow for unlimited repeated activation and deactivation of a downhole tool.
Various other hydraulic activation mechanisms make use of measurement while drilling (MWD) and/or other electronically controllable systems including, for example, computer controllable solenoid valves and the like. Electronic activation advantageously enables a wide range of activation and deactivation instructions to be executed and may further enable two-way communication with the surface. However, these activation systems tend to be highly complex and expensive and can be severely limited by the reliability and accuracy of MWD, telemetry, and other electronically controllable systems deployed in the borehole. As a result, there are many applications in which their use tends to be undesirable.
There remains a need in the art for a hydraulic activation assembly that enables a downhole tool, such as a stabilizer or reamer, to be repeatedly activated and deactivated any desired number of times during a drilling operation without breaking the tool string or tripping the tool out of the borehole. Such an assembly is preferably purely mechanical and therefore does not require the use of electronically controllable components.
In a first aspect, an indexing control system for a downhole tool comprises: an outer mandrel; an inner mandrel, disposed within the outer mandrel; a barrel cam, disposed on and affixed to the inner mandrel, comprising: a body, disposed on and affixed to the inner mandrel; a cam track formed in the body, comprising: a first loop track; a second loop track; and a transition track connecting the first loop track and the second loop track; and a pin, disposed on the outer mandrel, configured to engage the cam track, wherein a first downhole fluid pressure urges the barrel cam in a downhole direction, causing the pin to traverse a first portion of the first loop track from a first resting position to a second resting position, wherein a second downhole fluid pressure allows the barrel cam to move in an uphole direction, causing the pin to traverse a second portion of the first loop track from the second resting position to the first resting position, wherein a third downhole fluid pressure urges the barrel cam to move in a downhole direction, causing the pin to traverse a part of the first portion of the first loop track from the first resting position, and wherein a fourth downhole fluid pressure allows the barrel cam to move in an uphole direction, causing the pin to traverse the part of the first portion of the first loop track in a reverse direction and traverse the transition track toward the second loop track.
In a second aspect, a downhole tool assembly comprises: an outer mandrel; an indexing control system, comprising: an inner mandrel, disposed within the outer mandrel; a barrel cam, disposed on and affixed to the inner mandrel, comprising: a body, disposed on and affixed to the inner mandrel; a cam track formed in the body, comprising: a first loop track; and a transition track connecting the first loop track and a second loop track; and a pin, disposed on the outer mandrel, configured to engage the cam track; and a downhole tool connected to the outer mandrel, configured for activation and deactivation by the indexing control system, wherein a first downhole fluid pressure urges the barrel cam in a downhole direction, causing the pin to traverse a first portion of the first loop track from a first resting position to a second resting position, wherein a second downhole fluid pressure allows the barrel cam to move in an uphole direction, causing the pin to traverse a second portion of the first loop track from the second resting position to the first resting position, wherein a third downhole fluid pressure urges the barrel cam to move in a downhole direction, causing the pin to traverse a part of the first portion of the first loop track from the first resting position, and wherein a fourth downhole fluid pressure allows the barrel cam to move in an uphole direction, causing the pin to traverse the part of the first portion of the first loop track in a reverse direction and traverse the transition track toward the second loop track.
In a third aspect, a method of repeatedly activating and deactivating a downhole tool comprises: moving a pin in a first loop track of a cam track of a barrel cam, causing uphole and downhole movement of the barrel cam; moving the pin through a transition track of the cam track from the first loop track to a second loop track of the cam track; moving the pin in the second loop track, causing uphole and downhole movement of the barrel cam; and activating and deactivating the downhole tool by the uphole and downhole movement of the barrel cam, wherein moving the pin is caused by increasing or decreasing downhole fluid pressure.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of apparatus and methods consistent with the present invention and, together with the detailed description, serve to explain advantages and principles consistent with the invention. In the drawings,
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without these specific details. In other instances, structure and devices are shown in block diagram form in order to avoid obscuring the invention. References to numbers without subscripts are understood to reference all instances of subscripts corresponding to the referenced number. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.
As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, or the like, depending on the context.
Although particular combinations of features are recited in the claims and disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. Features may be combined in ways not specifically recited in the claims or disclosed in the specification.
Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim in combination with every other claim in the claim set. No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such.
During a typical drilling operation, drilling fluid (commonly referred to as “mud” in the art) is pumped downward through the drill string 170 and the bottom hole assembly (BHA) where it emerges at or near the drill bit 172 at the bottom of the borehole 180. The mud serves several purposes, including cooling and lubricating the drill bit 172, clearing cuttings away from the drill bit 172 and transporting them to the surface, and stabilizing and sealing the formations through which the borehole 180 traverses. The discharged mud, along with the borehole cuttings and sometimes other borehole fluids, then flows upward through the annulus 182 (the space between the drill string 170 and the borehole wall) to the surface. In various embodiments, tool assembly 110 makes use of the differential pressure between an internal flow channel and the annulus to selectively activate and deactivate certain tool functionality (e.g., the radial extension of a stabilizer structure outward from a tool body).
Those of ordinary skill in the art will understand that the deployment illustrated in
In one embodiment, tool assembly 110 may include a downhole tool such as a stabilizer configured for selective hydraulic activation and deactivation. As used herein, activating and deactivating means that features of the downhole tool may move relative to a tool body 120. For example, stabilizer structures 105 may be extended radially outward from the tool body 120 and retracted radially inward towards (or into) the tool body 120.
Turning now to
In
Indexing control section 210 may comprise a barrel cam 215, a pin 216 for engaging with the barrel cam 215, a first spring 217, and a second spring 219. The first spring 217 has a lower spring force than the second spring 219, as will be described in more detail below. The first spring 217 and the second spring 219 are biased to urge the barrel cam 215 in an uphole direction. The barrel cam 215, first spring 217, and second spring 219 are disposed on and affixed to an inner mandrel 260 between the inner mandrel 260 and an outer mandrel 250. The pin 216 is disposed through the outer mandrel 250, which holds the pin 216 in place during operation of the downhole tool assembly 200. Pin 216 is spring loaded, allowing pin 216 to stay engaged with tracks of varying depth in the barrel cam 215. In operation, the barrel cam 215 rotates and moves axially as urged by the pin 216, which moves within grooves formed on the circumference of the barrel cam 215, as described in more detail below. Downhole movement of the barrel cam 215 axially is caused by downhole fluid pressure urging the barrel cam 215 and inner mandrel 260 against the first spring 217 and second spring 219. The first spring 217 is mounted on a downhole portion of the barrel cam 215 and compresses against a sleeve 218 so that compression of the second spring 219 does not occur until the first spring 217 is compressed into the sleeve 218 so that the barrel cam 215 bears on the sleeve 218. The sleeve 218 is urged in an uphole direction by the second spring 219, with uphole movement of the sleeve 218 limited by stop pin 211. A pin 212 prevents downhole movement of the second spring 219. When the first spring 217 is compressed into the sleeve 218 far enough that the barrel cam 215 engages with the sleeve 218, further downhole movement of the barrel cam 215 causes the sleeve 218 to compress the second spring 219. When pumps are off, the second spring 219 urges the sleeve 218 against the stop pin 211 and the first spring 217 urges the barrel cam 215 uphole. By using two springs of different spring forces, finer control of the movement of the inner mandrel 260 may be achieved. However, embodiments of the downhole tool assembly may be manufactured with only a single spring, instead of two springs as illustrated and described herein.
Although a single pin 216 is illustrated in the
As illustrated in
As illustrated in
The basic structure of the cam track 810 is an alternating sequence of loop tracks of different lengths connected by transition tracks 850. Any number of tracks and transition tracks 850 may be provided. In one embodiment, the alternating sequence of loop tracks comprises alternating long loop tracks 830 and short loop tracks 840. The transition tracks 850 are not part of either the long loop tracks 830 or the short loop tracks 840 and provide a one-way transition path from one loop to the next.
Focusing now on the short loop track 840 of
If fluid pressure is reduced while pin 216 is traversing path 842 before reaching resting position 843, however, pressure from first spring 217, second spring 219, or both may push the barrel cam 215 in an uphole direction, causing pin 216 to traverse back through path 842, where step 844 prevents further movement towards resting position 841, so pin 216 instead traverses transition track 848 towards an adjacent long loop track 830. Transition track 848 is sloped towards the adjacent long loop track 830. Typically, this is accomplished by increasing fluid pressure by an amount less than necessary to urge the barrel cam 215 downhole far enough to reach resting position 843. Thus, after repeatedly cycling the barrel cam 215 by increasing and decreasing fluid pressure resulting in repeated traversals of the short loop track 840, the barrel cam 215 may be indexed toward the adjacent long loop track 830.
Increased fluid pressure will cause pin 216 to traverse the path from resting position 931 along path 932 towards resting position 933. Uphole from resting position 931, a step 934 prevents backward movement of the pin 216 towards resting position 931. When pin 216 is in resting position 933, reducing fluid pressure allows pin 216 to traverse paths 935, 936, and 937, ending back in resting position 931. Resting position 933 is stepped down from path 932, preventing reverse traversal of path 932 once pin 216 reaches resting position 933. This traversal may be performed repeatedly as many times as desired.
If fluid pressure is reduced while pin 216 is traversing path 932 before reaching resting position 933, however, pressure from first spring 217, second spring 219, or both may push the barrel cam 215 in an uphole direction, causing pin 216 to traverse back through path 932, where step 934 prevents further movement towards resting position 931, so pin 216 instead traverses transition track 938 towards an adjacent short loop track 840. Transition track 938 is sloped towards the adjacent short loop track 840. Typically, this is accomplished by increasing fluid pressure by an amount less than necessary to urge the barrel cam 215 downhole far enough to reach resting position 933. Thus, after repeatedly cycling the barrel cam 215 by increasing and decreasing fluid pressure resulting in repeated traversals of the long loop track 830, the barrel cam 215 may be indexed toward the adjacent short loop track 840.
Although described above in terms of a single pin 216, typically a plurality of pins 216 are employed, spaced around the outer mandrel 250, with each pin 216 traversing either a long loop track 830 or a short loop track 840, depending on the index position of the barrel cam 215. For example, as illustrated in
By employing a barrel cam 215 as illustrated and described above as an indexing control system, a downhole tool assembly 200 may be activated and deactivated repeatedly using purely mechanical elements with hydraulic pressure exerted by drilling mud. This provides an advantage over previous techniques that employed darts, balls, or the like, which could only be activated or deactivated a limited number of times, without the need for complex electronic control systems. Although described and illustrated in terms of a stabilizer, as explained above the techniques described herein can be used in a variety of other downhole tools where such repeated activation and deactivation cycles may be desired in either onshore or offshore settings.
In addition to providing a method for repeatedly activating or deactivating the downhole tool assembly, because activation and deactivation are signaled by changes in fluid pressure, such as by turning the mud pump off and on, activation and deactivation can be achieved faster with the system described above, reducing costs for the drilling operator. Balls and darts can take a relatively long time to flow through the drilling mud downhole at the relevant drilling depths. In contrast, changes in fluid pressure traverse through the drilling mud at the speed of sound, so may reach the indexing control system much faster than a ball or dart. Furthermore, by using an alternating sequence of two different length loops, the indexing control system can potentially cause two different activation and deactivation sequences, each one controlled by a different one of the loop tracks described above.
While certain example embodiments have been described in detail and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not devised without departing from the basic scope thereof, which is determined by the claims that follow.
