DRAWWORKS SYSTEM

BACKGROUND

Drawworks units have operated on drilling rigs since the advent of the drilling industry. Over the years, several developments have been made in respect of the power and speed of the units, which are becoming more powerful and controllable.

Over this time period, the basic premise of the unit has remained much the same. The drawworks units utilize a gearbox arrangement driven by a motor unit, which connects mechanically through the gearbox to a drawworks drum, which is used to wind-up and wind-down the wireline of the rig. Safety devices over time have been added to ensure a fail safe operation of the drawworks.

Typically the motors can be direct current (DC) or alternating current (AC) drives. In more modern times, the industry is moving to Variable Frequency Electrical drive control giving rise to single ratio gearboxes. Previously, drive limitations resulted in using variable speed gearboxes, which required gear changes in operation to achieve the desired performance.

Gearbox arrangements have evolved over the years to become more powerful and compact, but are still largely based on a pinion gear arrangement, with the input of the pinion drive gearbox connected to the drive motor and the output connected to the wireline drum. This leads to a larger sized drawworks with less design flexibility. Also, with current pinion drive gearboxes there is always the risk to overspeed the drive system. In overspeed, the torque created by the wireline load can “drive” the drawworks drum, which in turn can drive back through the gearbox into the electrical drive. For this reason, a brake system is used to control the drum operation. Similarly, if there were a gearbox failure, the drum could free run under the load from the wireline if the braking system were unavailable.

SUMMARY

According to aspects of the present disclosure, an example drawworks may include an electrical drive motor and an output shaft driven by the electrical drive motor. A worm gear may be coupled to the output shaft and a bull gear may be engaged with the worm gear. A wireline drum may be coupled to the bull gear and receive rotation from the electrical drive motor through the bull gear. The electrical drive motor, worm gear, and bull gear may comprise a drive unit that is removably coupled to the wireline drum. In certain embodiments, the electrical drive motor may comprise a drive motor module removably coupled to the work gear. The wireline drum may form a drum unit with at least one spigot coupled to the drum, which may be removable coupled to the drive unit.

Embodiments of the drawworks described herein may offer improved compactness, for installation on the rig floor, and power density, to enable greater power capability and greater lift capacity in a smaller footprint. The drawworks described herein also may be used to precisely control the release and rewind of the wireline cable is particularly useful for an automated drilling application. Specifically, by controlling the precise feed-rate of the wireline, the drilling operation does not get overloaded from releasing too much wireline too quickly. Similarly, precise control during the rewind of the wireline on the drawworks drum can lighten the load during the drilling operation.

Additionally, certain worm gear arrangements described herein that may show self-locking tendencies depending on the configuration of and load on the worm gear. The self-locking tendency of the worm gear arrangement arises from the fact that the gearbox has to be driven via the input shaft to operate the worm gear. Under certain load situations, the larger “bull gear” cannot turn the worm gear and the gearbox simply locks-up. Consequently, in those load situations, there is little risk of an overrun situation should the drive system be lost, except in the cases of an actual failure of the worm gearbox, such as the shearing of the gear teeth, before a catastrophic failure would occur. The risk of an actual failure can be further mitigated by using a gearbox with an overload rating with a substantial safety factor, at which point other structural issues would be required before failure, e.g. wireline breakage, or mast structure collapse.

Moreover, certain modular constructions of the drawworks may provide flexibility in terms of design, repair and maintenance. For example, the drive motor modules may provide flexibility on the amount, orientation, and power of the electrical drive motors, which may comprise 1150 hp and 1500 hp electrical AC motors allowing an operation power range from 1150 to up to 9000 hp.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete and thorough understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings.

FIG. 1 is a diagram of an example drilling rig that utilizes drawworks, according to aspects of the present disclosure.

FIG. 2 is diagram illustrating an example drawworks embodiment, according to aspects of the present disclosure.

FIGS. 3A-C are diagrams illustrating another example drawworks embodiment, according to aspects of the present disclosure.

FIGS. 4A-C are diagrams illustrating another example drawworks embodiment, according to aspects of the present disclosure.

FIGS. 5A-C are diagrams illustrating another example drawworks embodiment, according to aspects of the present disclosure.

FIGS. 6-12 are diagrams illustrating another example drawworks embodiment, according to aspects of the present disclosure.

FIGS. 13 and 14 are diagrams illustrating another example drawworks embodiment, according to aspects of the present disclosure.

FIGS. 15 and 16 are diagrams illustrating another example drawworks embodiment, according to aspects of the present disclosure.

FIG. 17 is a chart illustrating the relationship between drive power and different motor configurations.

FIG. 18 is a chart illustrating the relationship between drive power and different motor configurations.

DETAILED DESCRIPTION

For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communication with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components. It may also include one or more interface units capable of transmitting one or more signals to a controller, actuator, or like device.

For the purposes of this disclosure, computer-readable media may include any instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, for example, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk drive), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, RAM, ROM, electrically erasable programmable read-only memory (EEPROM), and/or flash memory; as well as communications media such wires, optical fibers, microwaves, radio waves, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing.

Illustrative embodiments of the present disclosure are described in detail herein. In the interest of clarity, not all features of an actual implementation may be described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the specific implementation goals, 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 the present disclosure.

The terms “couple” or “couples” as used herein are intended to mean either an indirect or a direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect mechanical or electrical connection via other devices and connections. Similarly, the term “communicatively coupled” as used herein is intended to mean either a direct or an indirect communication connection. Such connection may be a wired or wireless connection such as, for example, Ethernet or LAN. Thus, if a first device communicatively couples to a second device, that connection may be through a direct connection, or through an indirect communication connection via other devices and connections. The indefinite articles “a” or “an,” as used herein, are defined herein to mean one or more than one of the elements that it introduces.

FIG. 1 is a diagram of an example drilling rig 1 that utilizes drawworks 2, according to aspects of the present disclosure. The drawworks 2 is mounted to a rig floor 3 and comprises a wireline 4 that extends from the drawworks 2 to a pulley 5, otherwise known as a crown block, mounted on the rig 1. The drawworks 2 may raise and lower drill pipe 6 within a wellbore 7 in a subterranean formation 8 by extending or retracting wireline 4 over the pulley 5. Specifically, the wireline 4 may be coupled to a traveling block 9 that is suspended and moved by the wireline 4 as it is extended and retracted. The traveling block 9 in turn may be coupled to the drill pipe 6 through one or more intermediate mechanisms.

The drawworks 2 comprises a wireline drum 10 around which the wireline 4 is wound. The drawworks 2 furthers comprise at least one motor 11a and 11b that directly or indirectly rotates the drum, causing the wireline 4 to extend or retract. The motor may comprise, for example, an electrical drive motor coupled to a power source (not shown) and a control unit (not shown). In the embodiment shown, the electrical drive motors 11a and 11b, positioned on opposite sides of the drum 10, cooperatively respond to control signals from the control unit by either rotating the drum 10 in a first direction to extend the wireline 4 or rotation the drum 10 in a second direction to retract the wireline 4.

The drawworks 2 may further comprise a transmission system through which the electrical drive motors 11a and 11b drive the drum 10. The transmission system may comprise gears coupled to the drum 10 and electrical drive motors 11a and 11b that interact to rotate the drum 10 using power from the motors 11a and 11b. According to aspects of the present disclosure, the transmission system may comprise at least one worm gear coupled directly or indirectly to at least one of the electrical drive motors 11a and 11b and at least one bull gear coupled directly or indirectly to the drum 10 and engaged with the worm gear. As will be described below, the use of the worm gear in the transmission system may provide improved control and power responses at the drawworks 2, as well as a self-locking tendency that may be utilized in certain embodiments.

FIG. 2 is a layout of an example drawworks embodiment, according to aspects of the present disclosure. The drawworks 200 comprises a wireline drum 202 around which a wireline 204 is wrapped. The drum 202 is characterized by a longitudinal axis 206 and comprises a spigot 208 that allows the drum 202 to rotate around the axis 206. The spigot 208 may extend the length of the drum 202 or may be coupled to the drum 202 at a first end 210 of the drum 202 with respect to the axis 206. The drum 202 further may comprise a second spigot (not shown) or an extension of the spigot 208 that is coupled to or extends from a second end 212 of the drum 202 with respect to the axis 206.

Drawworks 200 further comprises a drive unit 214 comprising four motors 214a-d, each of which may comprise an electrical drive motor, such as a variable frequency drive motor. As can be seen, each motor 214a-d may comprise separate power supplies/controllers 250a-d pointed towards the second end 212 of the drum 202. Some or all of the motors 214a-d may comprise mounting brackets 252. In the embodiment shown, the motors 214a-d are all positioned on one side of the drum 202, with motors 214a and 214b positioned proximate to the second end 212 of the drum 202 and motor 214c and 214d positioned proximate to the first end 210 of the drum 202. The number of motors and the orientation of the motors with respect to the ends 210 and 212 of the drum 202 and the sides of the drum 202 may be altered, depending on the application.

The motors 214a-d may rotate the drum 202 using a transmission system that includes at least one worm gear 216 coupled to the motors 214a-d and at least one bull gear 218 engaged with the worm gear 216. In the embodiment shown, the bull gear 218 is coupled to the spigot 208 of the drum 202 and causes the drum 202 to rotate about the axis 206 in response to rotational movement from the worm gear 216. The worm gear 216 may rotate about a longitudinal axis that is perpendicular to the axis 206. As can be seen, the transmission system may comprise more than one bull gear, with a second bull gear 220 being coupled to the drum 202 at the second end 212.

According to aspects of the present disclosure, the worm gear 216 may be driven by and directly or indirectly coupled to one or more of the motors 214a-d. In the embodiment shown, the worm gear 216 is driven by and indirectly coupled to two motors 214c and 214d through a pinion gearbox 222. As can be seen, each of the motors 214c and 214d may drive corresponding output shafts 224 and 226 that are coupled to gears 228 and 230 of the pinion gearbox 222. Rotational movement of the gears 228 and 230 within the pinion gearbox 222 may produce rotational movement at an output shaft 232 of the pinion gearbox 222, which is coupled to and drives the worm gear 216. Accordingly, rotational movement generated by the motors 214c and 214d may be used to rotate the drum 202 and control how the wireline 204 is paid out.

A similar transmission system may be used with respect to motors 214a and 214b and bull gear 220. Specifically, the motors 214a and 214b may be coupled to and drive a second pinion gearbox 234, which drives the drum 202 through the second bull gear 220 using a second worm gear (not shown). In certain embodiments, the motors 214a-d may be connected to a single controller in a “digital gearing” configuration to ensure that all motors respond equally to a control input to perform a synchronous operation. Although a drawworks embodiment with multiple pinion gearboxes driven by multiple motors is shown, other embodiments are possible, including those in which a single pinion gearbox, driven by a single motor, drives a single worm gear/bull gear arrangement.

In addition to altering the number of motors and gearboxes, the relative orientations of the motors and gearboxes with respect to the drum may be altered based on design considerations. FIGS. 3A-C are diagrams illustrating another example drawworks embodiment, according to aspects of the present disclosure. As can be seen, the motors 301a-d have been flipped when compared to the embodiment of FIG. 2, as illustrated by the mounting brackets 352a-d of the motors 301a-d being pointed upwards and the power supplies/controllers 350a-d being pointed toward a first end 320 of the drum 305. Despite the fact that the motors 301-a-d are rotated, they utilize a transmission system similar to the one in FIG. 2, with motors 301a and 301b configured to drive pinion gears 302b, motors 301c and 301d configured to drive pinion gears 302a, the output shafts of pinion gears 302a and 302b configured to drive worm gears 303a and 303b, respectively, and the worm gears 303a and 303b configured to drive respective bull gears 304a and 304b, both of which are connected to the drum 305. FIGS. 4A-C illustrate a similar drawworks layout in which motors 401a-d are in another orientation yet utilize pinion gears 402a and 402b similar to those described above.

Although the drawworks embodiments in FIGS. 2-4C all utilize four motors, embodiments with fewer or greater numbers of motors are possible. FIGS. 5A-C illustrate yet another drawworks embodiment, according to aspects of the present disclosure, which comprises six motors 501a-f, the additional motors improving the power output at the drum 506. As can be seen, the embodiment comprises two sets of pinion gears 502a and 502a, similar to the embodiments above, but each seat of pinion gears is driven by three motors, rather than two. Specifically, motors 501a, 501b, and 501f drive pinion gears 502b, while motors 501c, 501d, and 501e drive pinion gears 502a. Notably, the motors 501a-f are arranged such that the resulting footprint of the drawworks configuration 500 is the same as the footprint of the embodiments described above. Accordingly, the power output of the drawworks may be improved within increasing the amount of space occupied by the drawworks on the rig.

The drawworks embodiments described thus far have included pinion gearboxes between the drive motors and the worm gears, but other embodiments may include a direct connection between a drive motor and a worm gear. This may advantageously result in a scaled down transmission system that may further reduce the footprint of the drawworks. FIG. 6-12 are diagrams illustrating various views of an example drawworks 600 according to this embodiment. For example, FIG. 6 illustrates a view of drawworks 600 enclosed by an outer housing 602, while FIGS. 7-12 show the unenclosed drawworks 600 from different viewpoints. Like the embodiments described above, the drawworks 600 comprises a drive unit with at least one electrical drive motor 604 and 606 that drives a drum 608 through at least one worm gear (not shown) coupled to the electrical drive motor and a bull gear (not shown) engaged with the worm gear and coupled to the drum 608. Unlike the embodiments described above, however, the drawworks 600 does not use pinion gears and has its primary elements collected into modular units that may be individually assembled, disassembled, and replaced without the other modular units having to be disassembled and replaced. That said, the modularity described below can be used with any of the drawworks embodiments described herein.

In the embodiment shown, the modular units may comprise a drum unit 660 and a drive unit 670. The drum unit 660 may comprise the drum 608 and at least one spigot coupled to an end of the drum 608. In the embodiment shown, the drum unit 660 comprises two spigots 610 and 612 projecting from opposite ends of the drum 608. The spigots 610 and 612 may be integrally formed with the drum 608 or may comprise interchangeable spigot units removably coupled to the drum 608, such as through bolts. Like the drums described above, the drum 608 may be characterized by a longitudinal axis 650, and the spigots 610 and 612 may allow the drum 608 to rotate around the axis 650.

The drum unit 660 may be supported by at least one pedestal bearing unit that allows the drum 608 to rotate smoothly around the axis 650. In the embodiment shown, drawworks 600 comprises two pedestal bearing units 614 and 616 coupled to a primary platform 618, the pedestal bearing units 614 and 616 supporting spigots 610 and 612, respectively, allowing the drum 608 to rotate. The pedestal bearing units 614 and 616 may comprise typical Pillar Block style bearing units or specially fabricated bearing housings when higher loads are required. During operation, the drum unit 660 may be removed and replaced from the pedestal bearing units 614 and 616 without requiring disassembly of the drive unit 670.

The drive unit 670 may comprise at least one electrical drive motor and a worm gear, and may be removably coupled to the drum unit 660, such as through bolts. In the embodiment shown, the drive unit 670 comprises the electrical drive motors 604 and 606 and a worm gearbox 620 containing a worm gear (not shown) and a bull gear (not shown) engaged with the worm gear in an arrangement similar to those described above. The drive unit 670 may be removably coupled to the drum unit 660, for example, at an interface 622 between the pedestal bearing unit 614 and the worm gearbox 620 or an interface 624 between the pedestal bearing unit 614 and the drum 608. In particular, the spigot 610 of the drum unit 660 may be coupled to the bull gear within the worm gearbox 620 at one of the interfaces, allowing rotation generated at the electrical drive motors 604 and 606 to be transmitted to the drum 608. Notably, by providing a removable coupling between the worm gearbox 620 and the spigot 610, the drum unit 660 may be removed and replaced without disassembling the drive unit 670, as can the worm gearbox 620 without disassembling the drum unit 660.

The electrical drive motors 604 and 606 may be coupled to one or more worm gears within the worm gearbox 620 through output shafts 626 and 628, respectively. The electrical drive motors 604 and 606 may rotate the respective output shafts 626 and 628, which in turn causes the worm gears coupled to the output shafts 626 and 628 to rotate. As described above, a bull gear within the worm gearbox 620 may be engaged with the worm gears, and the rotation of the worm gear by the electrical drive motors 604 and 606 may cause the bull gear and the drum unit 606 coupled to the bull gear to rotate.

In the embodiment shown, the electrical drive motors 604 and 606 are incorporated into electrical drive input motor modules, which may comprise submodules of the drive unit 670. Electrical drive motor 604, for example, may be incorporated into a module that includes the motor 604 and a motor base 630 to which the motor 604 is coupled. Similarly, the electrical drive motor 606 may be incorporated into a module that includes the motor 606 and a motor base 632 to which the motor 606 is coupled. The motor bases 630 and 632 may be removably coupled to the primary base 618, allowing both motors 604 and 606 to be swapped out within altering the placement of the primary base. Additionally, the output shafts 626 and 628 may be removably coupled to the worm gearbox 620, allowing the motors 604 and 606 to be disconnected from the worm gearbox 620 and new motors to be attached without affecting the placement and configuration of the worm gearbox 620. Conversely, the worm gearbox 620 may be disconnected from the motors 604 and 606 and replaced with a new worm gearbox without affecting the configuration and placements of the motors 604 and 606.

The worm gearbox 620 may be considered self-locking, but in certain conditions (gearing geometry and ratio), the bull gear may indeed drive the worm gear subject to loading conditions. In this instances, the reverse drive may cause the gearbox 620 to become a reduction unit, i.e the forces being applied to turn the bull gear are reduced through the drive train, providing a natural resistance to the turning motion. The resistance to turning is beneficial to the overall braking function of the drawworks, as (if required) a smaller dynamic brake unit can be employed. Alternatively regenerative braking can be employed via the electric drive motor.

In the embodiment shown, the drawworks comprises a brake 634. The brake 634 may comprise a brake rotor (disc) and one or more brake calipers that clamp onto the spigot 612 to prevent the drum 608 from rotating. In certain embodiments, the brake calipers may be configured as “spring on, hydraulic off,” meaning that during operation, hydraulic power is required to keep the calipers from braking. In the event there is a hydraulic power loss, the mechanical spring operation may automatically engage the calipers with the rotor, preventing any further rotation of the drum until the power is restored. In certain embodiments, the brake rotor may be directly connected to the drum unit 670.

Other embodiments of drawworks with a direct connection between the electric drive motor and worm gear are possible, including embodiments where the orientation and number of electric drive motors differs. FIGS. 13 and 14 are diagrams illustrating two views of another one such embodiment. In particular, FIGS. 13 and 14 illustrate a drawworks 700 with similar elements described above, including drum unit 702, pedestal bearing units 704 and 706, worm gearbox 708, and electric drive motor 710. As can be seen, the orientation of the worm gearbox 708 and electric drive motor 710 have been changed such that the electric drive motor 710 is oriented vertically next to the worm gearbox 708 and mounted over a primary platform 712. In certain embodiments, additional equipment may be added to supplement or augment the drum and motor, such as an oil cooler for the gearbox 708 and a blower for the electric drive motor 710. FIGS. 15 and 16 are diagrams illustrating a similar arrangement, in which two electrical drive motor 802 and 804 are arranged vertically on either side of a worm gearbox 806, on one side of a drum unit 806.

FIGS. 17 and 18 are charts illustrating the drive power that can be generated at a drawworks using different numbers of drive motors with different power ratings. In particular, FIGS. 17 and 18 demonstrate that the drive power to the drawworks can be increased by the addition of a second drive unit to the opposite end of the winching drum, or by altering the power capabilities of the drive motors. For example, FIG. 17 illustrates variants using 1150 horsepower motors, while FIG. 18 illustrates variants using 1500 horsepower motors. Other arrangements using motors with varying horsepower may be used, such as 3000 horsepower motors. By configuring the number of drive motors and the power rating, the drawworks can be customized to suit particular drive and lifting requirements. The power ranges FIGS. 17 and 18 illustrate typical ranges that can be achieved, although other ranges can be achieved through the disclosed embodiments. .

The drawworks embodiments described herein, in conjunction with the Variable Frequency Drive (VFD) for the motors, ensures the drive cycle can be precisely controlled with predetermined acceleration and deceleration cycles, which overcomes the need for a dynamic brake to assist the retardation of the drum. The motors are configurable for the size and application of the load being hoisted, as illustrated in FIGS. 17 and 18. In the event that higher capacities are required, a second drive unit may be added to the opposite side of the drum unit. Because the very action of the worm gear bull wheel gearbox provides a natural braking operation, for the gearbox to operate normally, the primary motive force (e.g., the AC motors) has to be engaged. Utilizing the VFD technology, it is then possible to control precisely the turning motion of the drum, in either clockwise or counter clockwise direction. This level of control enhances the ability of the drawworks to be used as an Auto-Driller, whereby through controlling the feed-rate of the drill-pipe (via the hoisting operation), the drilling parameters can be more clearly defined and held. For example, if during drilling the resistance increases, the load on the bit can be decreased by reducing the feed-rate of the drilling equipment (via the hoisting). In this manner the drilling operation is closely controlled, reducing wear and breakage issues.

Another advantage of the above embodiments is a reduction in the overall length of the unit, which may be achieved by turning the drive axis through 90 degrees. Additionally, providing the drive motors to either side of the gearbox unit allows flexibility in the drive options, further allowing the drive to be tailored to the application.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention as defined by the following claims.

DRAWWORKS SYSTEM

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CPC

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CROSS-REFERENCE TO RELATED APPLICATION

Provisional Applications (1)