The present invention is directed to a method for adding a pipe section to a drill string. The pipe section comprises an inner pipe section and an outer pipe section, and the drill string comprises an inner pipe string and an outer pipe string. The method comprises the steps of attaching the pipe section to a carriage that is adapted to advance and rotate the pipe section, and aligning an end of the inner pipe section with an end of the inner pipe string. The method further comprises the steps of advancing the end of the inner pipe section towards the end of the inner pipe string, and rotating the inner pipe section in a first direction until the inner pipe section applies a first torque to the inner pipe string. The method further comprises the step of measuring a magnitude of the first torque, and if the measured magnitude of the first torque exceeds a predetermined threshold value, rotating the inner pipe section in a second direction opposed to the first direction.
The present invention is also directed to another method for adding a pipe section to a drill string. The pipe section comprises an inner pipe section and an outer pipe section, and the drill string comprises an inner pipe string and an outer pipe string. The method comprises the steps of attaching the pipe section to a carriage that is adapted to advance and rotate the pipe section, and advancing the pipe section towards an end of the drill string until the inner pipe section is in contact with the inner pipe string and the outer pipe section is in contact with the outer pipe string. The method further comprises the steps of applying a first torque to the outer pipe section that causes its rotation in a first direction. The first torque having a magnitude sufficient to produce interference between the outer pipe section and the outer pipe string. The method further comprises the steps of measuring the magnitude of the first torque, and stopping rotation of the pipe section if the magnitude of the first torque exceeds a predetermined threshold value.
Turning now to the figures,
With reference to
The dual-member drill string 16 is formed by assembling the inner string 20 and the outer string 22. The inner string 20 extends within the outer string 22, which is formed from a series of outer pipe sections 28 arranged in end-to-end engagement. Preferably, each adjacent pair of outer pipe sections 28 is coupled with a torque-transmitting threaded connection. The inner string 20 is formed of a series of inner pipe sections 26 arranged in end-to-end engagement. Preferably, each adjacent pair of inner pipe sections 26 is coupled with a torque-transmitting non-threaded connection. Adjacent inner pipe sections 26 have a “slip-fit” connection. A non-threaded connection for the inner pipe sections 26 permits swifter assembly of the drill string 16 than if a threaded connection is used.
In operation, the inner pipe string 20 is rotatable independently of the outer pipe string 22. The inner pipe string 20 rotates the drill bit 18, while the outer pipe string 22 steers the drill bit. Steering of the drill bit 18 is accomplished using a steering mechanism incorporated into the outer surface of the outer pipe string 22. The steering mechanism deflects the drill string 16 and drill bit 18 in the desired direction. Steering mechanisms known in the art are deflection shoes or bent subs. When drilling straight, both the inner and outer pipe string 20 and 22 rotate. When steering, only the inner pipe string 20 rotates.
Turning to
Turning to
With reference to
Each of the box ends 50 and 64 may be removably attached to an end of an inner pipe section 26 via a plurality of fasteners 61, as shown in
With reference to
Continuing with
With reference to
Continuing with
Turning back to
With reference to
While the dither or oscillating technique has improved the reliability of making aligned connections 46 or 58, the technique is known to cause wear on the connections. Wear is caused because the inner pipe section 26 continues to rotate until the set time period has expired or the set angular distance has been reached. Such rotation continues regardless of whether a proper torque transmitting connection 46 or 58 has already been established. Continued rotation means continued torque and stress applied to the connections 46 or 58.
Another issue encountered when making the connections 46 or 58 is the magnitude of the torque applied to the inner pipe section 26 being added to the inner pipe string 20. The carriage 34 is adapted to provide enough torque to rotate the entire drill string 16. However, significantly less torque is required to connect a new inner pipe section 26 to the inner pipe string 20. For example, 2,000 pounds-feet of torque may be required to rotate the drill string 16; whereas, 200 pounds-feet of torque may be required to rotate a single inner pipe section 26.
If 2,000 pounds-feet of torque is applied to the non-threaded connections 46 or 28, the connections may become damaged if the ends 48 and 50 or 60 and 64 are not fully engaged or are misaligned. Thus, it is known in the art to limit the magnitude of torque used to connect a new inner pipe section 26 to the inner pipe string 20 to only the magnitude of torque required to make the connection 46 or 58. However, wear is still imposed on the connection 46 or 58 because the inner pipe section 26 continues to rotate until the set time period has expired or the set distance has been reached.
The present connection method limits wear to the connections 46 or 58 by substituting a cyclic timed oscillation or oscillation through a set angle with a torque-dependent oscillation. With a torque-dependent oscillation, the direction of rotation of the inner pipe section 26 is automatically reversed once a desired magnitude of torque is measured within inner drill string 20. Thus, no excessive torque is applied to the connection 46 or 58.
Turning to
To start, the inner pipe section 26 is slowly rotated in a first direction, as shown by step 102. The inner pipe section 26 is rotated until the polygonal outer profile 62 of the pin end 60 applies a first torque to the polygonal inner profile 66 of the box end 64, as shown by step 104. Once the first torque is applied, a sensor included in the machine 10 will measure the magnitude of the first torque, as shown by step 106. If the magnitude of first torque exceeds a predetermined threshold value, the inner pipe section 26 will automatically reverse direction and rotate in a second direction, as shown by steps 108 and 110. The first and second directions are opposite clock directions. If the magnitude of the first torque does not exceed the threshold value, the inner pipe section 26 will continue rotating in the first direction, as shown by step 112.
The predetermined threshold value may be the magnitude of torque required to establish a torque transmitting connection 58. For example, the value may be at least 200 pounds-feet. By automatically reversing rotation of the inner pipe section 26 once this value is measured, no excessive torque is applied to the connection 58.
With reference to
Continuing with
When rotation of the inner pipe section 26 is reversed, the pin end 60 will rotate through the windows 70, shown in
The processor can be programmed to automatically stop rotation of the inner pipe section 26 if the time elapsed is less than the threshold value, as shown by step 122. The processor may also send an error notification to the operator if the threshold value is not met, as shown by step 122. The operator may then check the inner pipe section 26 for damage. If necessary, the operator may remove the inner pipe section 26 and start over. The processor may also log the event so that it may be diagnosed and analyzed, if desired. The processor may also automatically stop rotation of the outer pipe section 28 if the threshold value is not met.
Continuing with
After a proper torque-transmitting connection is established, any torsional resistance being applied to the inner pipe section 26 is preferably removed. The torsional resistance is removed in order to prevent unnecessary wear to the inner pipe section 26 as the outer connection is made. Torsional resistance is removed by rotating the inner pipe section 26 to an angular position that is intermediate the angular position of the inner pipe section 26 at the time the first and second torque were measured. Alternatively, the inner pipe section 26 may be rotated for a length of time equal to half of the threshold value of the elapsed time between measurement of the first and second torque. Once torsional resistance is removed from the inner pipe section 26, the end of the pipe section 26 may be brought completely together with an end of the inner pipe string 20.
With reference to
With reference to
The time it takes the pin end 60 or 48 to rotate between adjacent windows 70 or 72 may be determined using the below equation:
In which, Δ is the expected time, in seconds, it will take for the inner pipe section 26 to rotate through the window 70 or 72. Such value may be referred to as the “window time”. In which, α is the angle α for the windows 70 or 72, Θ is the rotational speed of the inner pipe section 26, in rotations per minute (rpm), and “6” is a constant that takes into account the conversion from rotations to degrees and the conversion from minutes to seconds.
Finally, “n” takes into account the number of areas along the inner pipe section 26 that may experience instances of no torsional resistance. One area this occurs is within the windows 70 or 72. Another area this may occur is between an inner pipe section 26 and its removably attached box end 50 or 64. The removable box end 50 or 64 may rotate relative to the inner pipe section 26 it is attached to. This relative rotation may provide instances where no torsional resistance is experienced between the box end 50 or 64 and the inner pipe section 26. Thus, an inner pipe section 26 with a removable box end 50 or 64 will have two areas that experience instances of no torsional resistance. In contrast, if the box end 50 or 64 is welded to or integral with the inner pipe section 26, there is no relative rotation between the inner pipe section 26 and its box end 50 or 64. Thus, only the windows 70 or 72 provide an area where no torsional resistance may occur.
The number of areas along the inner pipe section 26 that may experience instances of no torsional resistance also depends on whether the inner pipe section 26 is being connected to the spindle 36 or the drill string 16. If the inner pipe section 26 is being attached to the spindle 36 and has a removable box end 50 or 64, the inner pipe section will have two areas that may experience instances of no torsional resistance.
If the inner pipe section 26 is being connected to the inner drill string 20 and has a removable box end 50 or 64, the inner pipe section will have four areas that may experience instances of no torsional resistance. Two areas are found at the connection between the inner pipe section 26 and the spindle 36 and two areas at the connection between the inner pipe section 26 and the drill string 20. In contrast, if the box end 50 or 64 is welded to its pipe section 26, only one area is found at the connection between the inner pipe section 26 and the spindle 36, and one area at the connection between the inner pipe section 26 and the drill string 20.
Turning back to
Turning back to
In alternative embodiments, step 120 in
The number of inner pipe section 26 rotations in each direction may be limited by the time it takes the outer pipe section 28 to thread onto the outer pipe string 22. Thus, the number of times the inner pipe section 26 rotates in each direction may be controlled by controlling the speed at which the outer pipe section 28 connects to the outer pipe string 22.
Turning to
The preferred rotational speed of the outer pipe section 28 may be determined using the below equation:
In which, ω is the ideal rotational speed of the outer pipe section 28 in rpm, and “L” is the standoff 82, in inches. In which, “P” is the pitch of the thread, in inches, and Δ is the window time. In which, “n” is the number of desired rotation cycles of the inner pipe section 26. For example, if “4” is used in the equation, two cycles clockwise and two cycles counter-clockwise are accounted for. Finally, in which “60” is a constant for converting rotations per second into rpm.
Continuing with
The processor included in the machine 10 may be programmed to automatically make the above calculations based on the measurements of the chosen pipe sections and operator preferences. The operator preferences may vary throughout a single operation. If the preferences vary, the processor may continually update the calculations as new inputs are received.
With reference to
To start, the inner pipe section 26 is rotated in a first direction until a first torsional resistance is sensed, as shown by steps 202 and 204. Once sensed, a first angular position of the inner pipe section 26 is recorded, as shown by step 206. The inner pipe section 26 is then rotated in a second direction until a second torsional resistance is sensed, as shown by steps 208 and 210. Once sensed, a second angular position of the inner pipe section 26 is recorded, as shown by step 212. The processor compares the first angular position to the second angular position and determines a median angular position, as shown by steps 214 and 216. The inner pipe section 26 is then oriented at the median angular position, as shown by step 218. Once in the median angular position, the ends 60 and 64 are forced the remainder of the distance together, making the connection 58, as shown by step 220. The inner pipe string 20 may then be held stationary while the outer pipe section 28 is threaded onto the outer pipe string 22. Alternatively, the outer connection may be made at the same time as the connection 58. The same method 200 may be used to make the connection 46.
Turning to
To start, the outer pipe section 28 is advanced towards the outer drill string 22 until the adjacent ends 38 and 40 are in contact with one another, as shown by step 302. The outer pipe section 28 is rotated in a first direction, as shown by step 304. The processor measures a magnitude of torque required to rotate the outer pipe section 28, as shown by step 306. If the magnitude of torque exceeds a predetermined threshold value, rotation of the outer pipe section 28 is stopped and an error notification is sent to the operator, as shown by step 308. The threshold value may be 1,000 pounds-feet. If the magnitude of torque does not exceed the threshold value, the outer connection may be completely made, as shown by step 310.
Turning to
To start, the magnitude of torque applied to the inner pipe section 26 to be removed from the inner pipe string 16 is measured, as shown by step 402. If the magnitude exceeds a threshold value, the inner pipe section 26 is rotated in a counter-clockwise direction, as shown by steps 402 and 404. A sensor will continually measure the magnitude of torque applied to the inner pipe section 26, as shown by step 406. The carriage 34 will continue to rotate the inner pipe section 26 in a counterclockwise direction until the magnitude of the torque applied to the inner pipe section 26 is below the threshold value. The threshold value may be, for example, 200 pounds-feet.
If the magnitude of torque does not exceed the threshold value, the outer pipe section 28 may be rotated counter-clockwise so as to unthread the outer pipe section 28 from the outer drill string 22, as shown by step 406. The inner pipe section 26 is pulled from the inner pipe string 20 as the outer pipe section 28 unthreads from the outer pipe string 22. The method 400 may also be used when removing the spindle 36 directly from the drill string 16.
The above method is effective at removing torque from the inner pipe section. However, even with torsional resistance removed, the slip-fit connection may become “locked” during operation. The inner pipe sections 26 may become locked when in the operating torque-transmitting position, shown in
Preferably, locked connections are “unlocked” prior to removing a pipe section 24 from the drill string 16. The connection is unlocked when adjacent pipe sections may be rotatable within the angle α with little torsional resistance. If a connection 58 is not unlocked prior to disconnection, damage or wear may occur. Additionally, the connection 58 may fail to properly disconnect, which may negatively affect the proper functioning of the carriage 34 as will be discussed below.
A first method to unlock a locked connection is provided in
While rotating the pipe section 24 counterclockwise, torsional resistance in the counterclockwise direction is measured by the carriage 34 at 504. Torsional resistance will not be detected until the pin end 60 has rotated through the window 70 and engaged a second side 92 of the projections 68, as shown in
Once a threshold resistance is detected, for example, 200 pounds-feet, counterclockwise rotation is stopped. The threshold resistance is enough to unlock the inner pipe section 26 connections 58, but low enough to prevent counterclockwise rotation of a bit or backreamer. For each pipe section 24, there are two potentially locked inner pipe section 26 connections 58. Both connections may be unlocked during a single counterclockwise rotation.
Once the threshold resistance is detected, the inner pipe rotation may be reversed and rotated to relieve torque encountered in the counterclockwise direction at 506, as shown in
A number of variations can be made to the above described method. It may be desirable to vary the speed of counterclockwise rotation. For example, counterclockwise rotation may begin at max speed. Speed may then be slowed after an initial time interval has passed or after rotating a specified angle. For example, the angle may be equal to a multiple of a corresponding to the number of windows associated with a pipe section. Alternatively, speed may be varied in relation to the measured torsional resistance in the counterclockwise direction. Rotational speed is started at max speed and decreases once the measured torsional resistance approaches the measured threshold resistance.
Additionally, it may not be necessary to rotate the inner pipe section 26 counterclockwise more than a set number of revolutions. For example, two revolutions may be enough to unlock a locked connection 58. In this case, the inner pipe section will be rotated counterclockwise two revolutions or until the threshold resistance is detected, whichever occurs first. The number of revolutions may also depend on the length of the drill string 16 underground. The length of the drill string 16 continues to decrease as pipe sections 24 are removed from the drill string. The shorter the drill string 16, the easier it is to rotate the bit or backreamer. Therefore, the maximum number of counterclockwise revolutions allowed may decrease as pipe sections are removed from the drill string 16.
The inner pipe string connections shown in the Figures are considered “pin-up” connections. “Pin-up” inner pipe sections 26 are attached together by holding the pin end of an inner pipe section at the first end of the drill string 16 stationary, while the box end of an inner pipe section encloses around the pin end.
In alternative embodiments, the inner pipe sections may be positioned “pin-down”. “Pin-down” inner pipe sections 26 are attached together by holding the box end 64 of an inner pipe section at the first end of the drill string 16 stationary, while the pin end of an inner pipe section is inserted within the box end. If the inner pipe sections 26 are “pin-down”, the inner pipe sections may be considered in an operating torque-transmitting position when the pin end engages with the second side of the projections, as shown in
It may be necessary to remove a pipe section 24 from the drill string 16 with a locked inner pipe connection 58. A carriage 34 comprising an assisted makeup system is known in the art. An example of an assisted makeup system is described in U.S. Pat. No. 7,011,166, the contents of which are incorporated herein by reference. A carriage 34 utilizing assisted makeup comprises a float sensor and a spring system. The spring system is configured to allow the spindle to move independently of, and parallel with, the carriage frame. The spring system provides the carriage with a float range. The float sensor measures the location of the spindle in relation to the float range. Once the spindle reaches an end of the float range pull-back force is stopped.
The purpose of an assisted makeup system is to prevent the carriage from providing excessive thrust or pull-back while connecting or disconnecting a pipe section from the drill string. For example, a carriage may be capable of 30,000 lbs. of pull-back. If this magnitude of pull-back was applied while unthreading an outer pipe section the pipe threads may be stripped or damaged. Therefore, the assisted makeup system may limit pull-back to 2,500 lbs. while disconnecting a pipe section.
If the assisted makeup system limits force while disconnecting a pipe section 34 it may lack the required pull-back force needed to disconnect a locked inner pipe connection 58. As a result, the assisted makeup system may need to account for a locked inner pipe connection 58. This is accomplished by turning off assisted makeup limits once the outer pipe section 28 has been separated from the drill string adequately. To accomplish this on a mechanical spring system the float sensor can be ignored at the proper moment for a limited time interval.
For example, each outer pipe section 28 comprises an outer shoulder which touch when a pair of outer pipe sections are fully threaded. Prior to disconnecting a pipe section from the drill string, the shoulders may need a predetermined amount of separation before the thread is fully disengaged. Once the shoulders are separated by this distance, the connection should be free to fully separate if the inner connection is properly disengaged. Separation distance can be measured by monitoring the location of the carriage in relation to the drill frame. One such predetermined distance that is used in an embodiment of the invention is 1.665″, though this particular dimension is non-critical. Alternatively, the outer rod may be rotated in the counterclockwise direction a predetermined number of revolutions.
If the inner connection 58 does not disengage, the inner rod connection is preventing separation and a peak force should be allowed to apply to the carriage 34 to aid in separating the inner pipe connection. This peak force may be instantaneous or allowed for a minimal time interval to avoid sustained loading. As described above, the assisted makeup may prevent loadings of the carriage above 2,500 lbs., but the instantaneous separation force can be allowed to peak at up to 5,000 lbs. or higher for a period of less than 0.25 seconds, or the shortest detectible measurement interval based on refresh rate of a sensor that measures the load on the carriage 34.
Alternatively, a virtual assisted makeup system may be utilized in lieu of the assisted makeup system. A virtual assisted makeup system is described in U.S. patent publication no. 2020/0217151, Ramos, et al., the contents of which are incorporated herein by reference. The virtual assisted makeup comprises a thrust sensor that continuously monitors the hydraulic system which powers the carriage. This system eliminates the need for the assisted makeup with a spring system and float sensor. A processor may be programmed to vary thrust and pull-back force at any time in response to measured variables.
As above, once the outer pipe section 28 has been separated from the drill string 16 the pull-back force may be increased momentarily to ensure separation of the inner pipe connection 58. However, rather than ignoring the mechanical spring system, the virtual assisted makeup may vary thrust as needed. For example, pull-back may be limited to 2,500 lbs. while unthreading the outer pipe section. Once the threaded connection has disengaged, pull-back may be momentarily increased to 5,000 lbs. to ensure disconnection of the inner pipe section.
Changes may be made in the construction, operation and arrangement of the various parts, elements, steps and procedures described herein without departing from the spirit and scope of the invention as described in the following claims.
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Number | Date | Country | |
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20210285293 A1 | Sep 2021 | US |
Number | Date | Country | |
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Number | Date | Country | |
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Parent | 16299903 | Mar 2019 | US |
Child | 17335895 | US |