BACKGROUND

The present disclosure relates to drilling wellbores into subterranean formations, and, more specifically, to systems and methods for automatically controlling a band brake handle of a drilling drawworks.

Drilling a wellbore into a subterranean formation often comprises both drilling and tripping operations. The drilling operation often includes rotary drilling in which a hole is made in the subterranean formation through continuous circular motion of a drill bit that breaks rock at the bottom of the hole. The drill bit is typically suspended from a collection of pipes, often referred to as a drill string. During drilling operations, the drill string is turned at the surface by a rotary table mechanism or top drive located on a drilling rig or similar lifting equipment. As this rotary motion is transferred to the drill bit, the drill bit gouges, scrapes, crushes, and/or breaks the rocks at the bottom of the hole thereby penetrating the subterranean formation and forming a wellbore.

The tripping operation often requires that the drill bit and/or drilling pipe be removed from the wellbore and/or introduced into the wellbore. Taking the drill bit out of the wellbore and onto the surface is commonly referred to as "tripping out of the hole." Introducing the drill bit into the wellbore and lowering it until the point that it contacts the rock face is commonly referred to as "tripping in the hole." A number of conditions may require tripping out of the hole and/or tripping in the hole, including, for example, completing a section of drilling and changing the drill bit.

Both drilling and tripping operations require that the drill string be raised and lowered in the wellbore. To do so, the drilling rig or similar lifting equipment may contain a band brake type drawworks drum that rotates to raise or lower the drill string. The speed at which the drill string is raised and lowered may be controlled by a band brake on the drawworks drum. Traditionally, the band brake is operated manually by an operator using a large handle to apply friction to the band brake. However, manually regulating the force applied to the drawworks band brake to maintain a constant drill string speed is very challenging for several reasons, including, but not limited to, non-linearity, response lag, parasitic response, temperature dependency, and torque lope. It is desirable to develop systems and methods for automatically controlling a band brake handle of a drilling drawworks. BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be more fully understood by reference to the following detailed description of the preferred embodiments of the present disclosure when read in conjunction with the accompanying drawings, in which like reference numbers refer to like parts throughout the views wherein:

FIG. 1 depicts an automated band brake drawworks system in accordance with illustrative embodiments of the present disclosure; and

FIG. 2 depicts a process control diagram for operating the automatic drilling systems of the present disclosure in accordance with illustrative embodiments of the present disclosure.

The disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the disclosure being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

DETAILED DESCRIPTION

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. To facilitate a better understanding of the present disclosure, the following examples of certain embodiments are given. In no way should the following examples be read to limit, or define, the scope of the disclosure.

The present disclosure relates to drilling wellbores into subterranean formations. More particularly, the present disclosure relates to systems and methods for controlling a band brake handle of a drilling drawworks.

Band brake type drilling drawworks may be utilized to raise and lower a drill string in a wellbore during drilling and tripping operations by adjusting the position of the band brake handle or shaft. The rate at which the drill string is raised and lowered is often critical to efficient and safe drilling and tripping operations. Maintaining a constant drill string speed using manual control of the band brake handle is very challenging due to, among other reasons, changing process conditions, non-linearity, and response lag. Thus, systems and methods for automatically controlling the band brake handle of a drilling drawworks based on process conditions may result in more efficient and safe drilling and tripping operations.

Several techniques exist for automating the control of the band brake including using wire pulling with safety spring systems, pneumatic actuation, and hydraulic actuation. However, there techniques have several disadvantages including, but not limited to, imprecise control and limited application to drilling.

Among the many potential advantages to the systems and methods of the present disclosure, only some of which are alluded to herein, the systems and methods of the present disclosure may provide a band brake control apparatus that may be couple to the band brake handle in such a way that allows for the benefits of directly engaging the band brake handle with the band brake control apparatus while maintaining the ability to operate the band brake handle manually in the event of an emergency. The manner in which the band brake control apparatus of the present disclosure may be coupled to the band brake handle also may allow for the response and force required for the fast actuation used in tripping operations. The systems and methods of the present disclosure also may allow for automatic control of existing band brake type drilling drawworks by providing the ability to retrofit the apparatuses of the present disclosure onto existing drawworks drums even when space around the band brake handle and shaft is limited.

FIG. 1 depicts an automated band brake drawworks system 100 in accordance with illustrative embodiments of the present disclosure. The automated band brake drawworks system 100 may comprise a drawworks drum 102 and a band brake 104. In certain embodiments, the band brake 104 may before formed of steel or other suitable material with a band of friction material on its interior surface that tightens concentrically around the braking flange of the drawworks drum 102. In certain embodiments, the band brake 104 may comprise a band brake shaft 105 and a band brake handle 106. The band brake 104 is anchored at one end, and is movable at its other end through a connection via the band brake shaft 105 to the band brake handle 106. The band brake handle 106 is arranged such that when the band brake handle 106 is lifted, the band brake 104 is released from engagement with the drawworks drum 102. Releasing the band brake 104 enables the drawworks drum 102 to rotate such that gravity can draw a drill string wound around the drawworks drum 102 (not illustrated herein) down into a wellbore. The linear motion of the drill string wound around the drawworks drum 102 is converted into axial rotation of the drawworks drum 102. Lowering or releasing the band brake handle 106 causes the band brake 104 to engage with the drawworks drum 102 and the rotation of the drawworks drum 102 is slowed or stopped. Alternatively, the band brake 104 can be controlled in a similar manner using the band brake shaft 105.

The automated band brake drawworks system 100 may further comprise an electric linear actuator 1 10 coupled to the band brake handle 106 and/or the band brake shaft 105 by a detachable latch 108. In certain embodiments, the detachable latch 108 may comprise a magnetic latch, an electromagnetic latch, and/or a mechanical latch. In certain embodiments, the detachable latch 108 may be directly coupled to the band brake handle 106 and/or the band brake shaft 105 and detachably coupled to the electric linear actuator 1 10. The electric linear actuator 1 10 may be operatively coupled to a motor (not shown in FIG. 1). In certain embodiments, the motor may be internal to the electric linear actuator 1 10. Motors suitable for use in accordance with the present disclosure include, but are not limited to, AC motors, stepper motors, and servo motors. In certain embodiments, the rotational motion of the motor may be converted to linear motion of the electric linear actuator 1 10.

In certain embodiments, electric linear actuator 1 10 (or the motor operatively coupled thereto) may be operatively coupled to a motor drive 1 12, which in turn may be operativeiy coupled to the controller 1 14. Motor drives suitable for used in accordance with the present disclosure include, but are not limited to, servo drives, stepper drive, and/or variable frequency drives. In such embodiments, the motor drive 112 may control the speed and/or torque of the motor that drives the electric linear actuator 1 10 based on one or more control inputs from a controller 1 14. In certain embodiments, the motor may internally contain a shaft encoder that measures motor shaft position in response to a change in voltage from the motor drive 1 12. In certain embodiments, the shaft encoder may be operatively coupled to the motor drive 112. The motor drive 1 12 may use the shaft position feedback to regulate the torque of the motor. In certain embodiments, the motor drive 1 12 may be programmed to operate a closed loop to regulate the torque of the motor.

A drum position encoder 1 16 may be rotationally coupled to the drawworks drum 102 and operatively coupled to the controller 1 14. In certain embodiments, the drum position encoder 1 16 may generate signals corresponding to drawworks drum position measurements 102 over time. The controller 1 14 may receive the signals generated by the drum position encoder 1 16 and determine the rate of rotation of the drawworks drum 102 using the variation of the drawworks drum position over time. In certain embodiments, the controller 1 14 may be programmed to operate a proportional integral derivative (PID) control loop to generate a control signal based on the difference between the determined rate of rotation of the drawworks drum 102 and a rate of rotation setpoint. The motor drive 112 may be operatively coupled to the controller 1 14 to receive the control signal such that the motor drive 112 operates the electric linear actuator 1 10 and/or the motor operatively coupled thereto to move the band brake handle 106 and/or the band brake shaft 105. In certain embodiments, the motor drive 1 12 adjusts the acceleration of, the speed of, and/or the force applied by the electric linear actuator 1 10 to move the band brake handle 106 and/or the band brake shaft 105.

In certain embodiments, the automated band brake drawworks system 100 may further comprise a joystick 1 18 operatively coupled to the controller 1 14. The joystick 1 18 may be used to manually adjust the acceleration of, the speed of, and/or the force applied by the electric linear actuator 1 10 to move the band brake handle 106 and/or the band brake shaft 105. In certain embodiments, the band brake handle 106 and/or the band brake shaft 105 may be detached from the electric linear actuator 1 10 using the detachable latch 108 and the band brake handle 106 and/or the band brake shaft 105 may be manually operated.

FIG. 2 depicts a process control diagram for operating the automated band brake drawworks systems of the present disclosure in accordance with illustrative embodiments of the present disclosure. In certain embodiments, several sensors may be placed throughout the drilling rig, the drilling equipment, and/or the subterranean formation to measure process conditions. Such sensors may include, but are not limited to, weight-on-bit sensors, differential pressure sensors, and drilling torque sensors. In certain embodiments, one or more controllers 202 may be programmed to operate a proportional integral derivative (PID) control loop to generate one or more rate of penetration ("ROP") setpoints 204 based on the difference between the process condition measured by the sensor and a setpoint for that process condition. In certain embodiments, a ROP setpoint 206 also may be manually entered. In certain embodiments, the ROP setpoints 204 from the enable controllers 202 and the manually entered ROP setpoint 206 may be sent to a selector 208. The selector 208 may programmed to choose one of the ROP setpoints 204, 206 resulting in a selected ROP setpoint 210. In certain embodiments, the selector 208 may choose the lowest of the ROP setpoints 204, 206.

The selected ROP setpoint 210 may be sent to a controller 1 14. In certain embodiments, the controller 1 14 may contain block calibration logic 212. The block calibration logic 112 may be used along with manually entered information to convert the selected ROP setpoint 210 to a drawworks drum rate of rotation setpoint. The controller 1 14 may receive drawworks drum position measurements 214 over time from the drum position encoder 1 16 and may use these drawworks drum position measurements 214 to determine the current rate of rotation of the drawworks drum 102. The controller 1 14 may be programmed to operate a proportional integral derivative (PID) control loop to generate a control signal 216 based on the difference between the determined rate of rotation of the drawworks drum 102 and the drawworks drum rate of rotation setpoint. The control signal 216 and a manual input from a joystick 1 18 may be sent to a selector 218. The selector 218 may choose either the control signal 216 or the manual input from the joystick 1 18 based, at least in part on, the operation mode (drilling or tripping) and/or the level of the signal from the joystick indicating operator input.

In certain embodiments, the selected signal 220 may be sent to the motor drive 1 12 as the linear actuator setpoint 226. In some embodiments, the selected signal 220 first may be sent to a signal addition block 222. In such embodiments, the signal addition block 222 also may receive an input from a pulse generator block 224. The pulse generator block 224 may be configured to generate a wave (i.e., oscillating signal) of variable amplitude, frequency, and duty cycle. The selected signal 220 and the input from the pulse generator block may be added by the signal addition block 222 to generate a pulsating linear actuator setpoint 226. In such embodiments, the pulsating linear actuator setpoint 226 may be sent to the motor drive 1 12.

The motor drive 1 12 may regulate the control voltage and current applied to the electric linear actuator 1 10 based on the linear actuator setpoint 226 to adjust the acceleration of, the speed of, and/or the force applied by the electric linear actuator 110. In certain embodiments, the motor drive 112 may be programmed to operate a closed loop vector to regulate the torque of the motor that drives the electric linear actuator 1 10. In such embodiments, the motor drive 1 12 may receive shaft position feedback 228 from a shaft encoder on the motor to regulate the torque of the motor. One of ordinary skill in the art, with the benefit of this disclosure, will recognize that the motor drive 112 may be programmed to operate other control methods such as position, step, open loop vector, and/or V/f control.

The force of the electric linear actuator 1 10 may be transferred to the band brake handle 106 and/or the band brake shaft 105 through direct engagement via a detachable latch 108. The band brake handle 106 and/or the band brake shaft 105 may transfer the change in the applied force to the band brake 104 thus causing a change in the rate of rotation of the drawworks drum 102.

Therefore, the present disclosure is well-adapted to carry out the objects and attain the ends and advantages mentioned as well as those which are inherent therein. While the disclosure has been depicted and described by reference to exemplary embodiments of the disclosure, such a reference does not imply a limitation on the disclosure, and no such limitation is to be inferred. The disclosure is capable of considerable modification, alternation, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts and having the benefit of this disclosure. The depicted and described embodiments of the disclosure are exemplary only, and are not exhaustive of the scope of the disclosure. Consequently, the disclosure is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.