BACKGROUND
[0001] This section is intended to introducé the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be noted that these statements are to be read in this light, and not as admissions of prior art.
[0002] A blowout preventer (BOP) is installed on a wellhead to seal and control an oil and gas well during various operations. For example, during drilling operations, a drill string may be suspended from a rig through the BOP into a wellbore. A drilling fluid is delivered through the drill string and returned up through an annulus between the drill string and a casing that lines the wellbore. In the event of a rapid invasion of formation fluid in the annulus, commonly known as a "kick," the BOP may be actuated to seal the annulus and to control fluid pressure in the wellbore, thereby protecting well equipment positioned above the BOP. The construction of the BOP can affect operation of the BOP.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Various features, aspects, and advantages of the present embodiments will become better noted when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein:
[0004] FIG. 1 is a block diagram of an embodiment of a mineral extraction system;
[0005] FIG. 2 is a schematic diagram of an embodiment of a blowout preventer (BOP) that may be used in the mineral extraction system of FIG. 1; and

[0006] FIG. 3 is a side cross-sectional view of an embodiment of an actuation system that may be used in the BOP of FIG. 2.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS [0007] One or more specific embodiments of the present disclosure will be described below. These described embodiments are only exemplary of the present disclosure. Additionally, in an effort to provide a concise description of these exemplary embodiments, all features of an actual implementation may not be described in the specification. It should be noted that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be noted that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
[0008] The present embodiments generally relate to a blowout preventer (BOP) for a mineral extraction system. The BOP may include a first ram and a second ram that move toward and away from one another to adjust the BOP between an open position and a closed position. For example, a first gear system may be mechanically engaged with a first threaded shaft configured to move the first ram, and a second gear system may be mechanically engaged with a second threaded shaft configured to move the second ram. As used herein, mechanically engaged refers to physical coupling between components such that movement of one of the components may drive movement of another one of the components. In an example, gears may be mechanically engaged with one another via teeth such that one of the gears drives movement of another of the gears. In another example, teeth of a gear may be mechanically engaged with threads of a shaft such that movement of the gear drives movement of the shaft.

[0009] The first gear system may be coupled to a first motor (e.g., an electric motor, a pneumatic motor, a hydraulic motor), which may operate the first gear system to drive movement of the first threaded shaft and the first ram. The second gear system may be coupled to a second motor (e.g., an electric motor, a pneumatic motor, a hydraulic motor), which may operate the second gear system to drive movement of the second threaded shaft and the second ram. For example, movement of the threaded shafts by the first and second motors may cause the first ram and the second ram to move linearly toward and away from one another to adjust the BOP between the open position and the closed position. As discussed in more detail below, each gear system may include multiple gears coupled to one another in multiple stages to enable the motors to provide sufficiënt power and acute control of the movement of the rams. As such, the gear system may improve the structure and/or operation of the BOP.
[0010] While the disclosed embodiments are described in the context of a drilling system and drilling operations to facilitate discussion, it should be noted that the BOP may be adapted for use in other contexts and during other operations. For example, the BOP may be used in a pressure control equipment (PCE) stack that is coupled to and/or positioned vertically above a wellhead during various intervention operations (e.g., inspection or service operations), such as wireline operations in which a tooi supported on a wireline is lowered through the PCE stack to enable inspection and/or maintenance of a well. In such cases, the BOP may be adjusted from the open position to the closed position (e.g., to seal about the wireline extending through the PCE stack) to isolate the environment, as well as other surface equipment, from pressurized fluid within the well. In the present disclosure, a conduit may be any of a variety of tubular or cylindrical structures, such as a drill string, wireline, Streamline™, slickline, coiled tubing, or other spoolable rod.
[0011] With the foregoing in mind, FIG. 1 is a block diagram of an embodiment of a mineral extraction system 10. The mineral extraction system 10 may be configured to extract various minerals and natural resources, including hydrocarbons (e.g., oil and/or natural gas), from the earth or to inject substances

into the earth. The mineral extraction system 10 may be a land-based system (e.g., a surface system) or an offshore system (e.g., an offshore platform system). As shown, a BOP assembly 16 (e.g., BOP stack) is mounted to a wellhead 18, which is coupled to a mineral deposit via a wellbore 26. The wellhead 18 may include any of a variety of other components, such as a spool, a hanger, and a "Christmas" tree. The wellhead 18 may return drilling fluid or mud toward the surface 12 during drilling operations, for example. Downhole operations are carried out by a conduit 24 (e.g., drill string) that extends through a central bore 28 (e.g., flow bore) of the BOP assembly 16, through the wellhead 18, and into the wellbore 26.
[0012] To facilitate discussion, the BOP assembly 16 and its components may be described with reference to a vertical axis or direction 30, a first horizontal axis or direction 32 (e.g., an axial axis or direction), a second horizontal axis or direction 34 (e.g., an lateral axis or direction), and a circumferential axis or direction 36 (e.g., about the first horizontal axis 32). The BOP assembly 16 may include one or more BOPs 42 stacked along the vertical axis 30 relative to one another. One or more of the BOPs 42 may include opposed rams that are configured to move along the first horizontal axis 32 toward and away from one another to adjust the BOP 42 between an open position and a closed position. In the open position, the BOP 42 may enable fluid flow through the central bore 28. In the closed position, the BOP 42 may block fluid flow through the central bore 28.
[0013] The BOP assembly 16 may include any suitable number of the BOPs 42 (e.g., 1, 2, 3, 4, or more BOPs 42). Additionally, the BOP assembly 16 may include any of a variety of different types of BOPs 42 (e.g., having shear rams, blind rams, blind shear rams, pipe rams). For example, in certain embodiments, the BOP assembly 16 may include one or more BOPs 42 having opposed shear rams or blades configured to sever the conduit 24 to block fluid flow through the central bore 28 and/or one or more BOPs 42 having opposed pipe rams configured to engage the conduit 24 to block fluid flow through the central bore 28 (e.g., through an annulus about the conduit 24). In the disclosed embodiment,

at least one BOP 42 includes threaded shafts configured to rotate via a respective gear system to drive the rams toward and away from one another to adjust the BOP 42 between the open position and the closed position
[0014] FIG. 2 is a schematic diagram of an embodiment of the BOP 42 in an open position. In the open position, the BOP 42 may enable fluid flow through the central bore 28 (e.g., through an annulus between the conduit 24 and a wall defining the central bore 28). To this end, in the open position, a ram 100 is in a retracted position and does not contact the conduit 24 or an opposing ram (not shown). The BOP 42 also includes a housing 102 (e.g., a body) in which the ram 100 may be disposed and through which the central bore 28 may extend. An enclosure 104 (e.g., bonnet) of the BOP 42 may be coupled to the housing 102 and may enclose an actuator assembly 106 configured to couple to the ram 100 in the housing 102. The actuator assembly 106 may drive the ram 100 toward and away from the conduit 24 and/or an opposing ram axially along a first axis 108 (e.g., extending along the first horizontal axis 32) to adjust the BOP 42 between the open position and a closed position.
[0015] In some embodiments, the actuator assembly 106 may include a shaft 110 (e.g., threaded shaft; connector rod) configured to couple to the ram 100. The actuator assembly 106 may also include a gear system 112 engaging the shaft 110 and configured to drive the shaft 110 to move axially along the first axis 108 in order to move the ram 100 along the first axis 108 within the housing 102. By way of example, the gear system 112 may be a planetary gear system (e.g., a multi-stage planetary gear system) having multiple gears. At least one of the gears may mechanically engage with the shaft 110. During operation, the gears of the gear system 112 may rotate and/or revolve to cause the shaft 110 to move along the first axis 108. The illustrated gear system 112 includes a first stage 114 and a second stage 116. A stage of the gear system 112 may refer to a set of gears arranged at a section of the gear system 112 (e.g., extending radially outwardly from the shaft 110) along the first axis 108. In this way, the first stage 114 and the second stage 116 may be offset from one another along the first axis 108.

[0016] The first stage 114 of the actuator assembly 106 may be coupled to a first motor 118 and/or a second motor 120 (e.g., directly coupled via an interface between an output shaft and a gear of the first stage 114). The second stage 116 of the actuator assembly 106 may be coupled to the shaft 110 (e.g., directly coupled via an interface between a gear of the second stage 116 and the shaft 110). Operation of the first motor 118 and/or the second motor 120 may cause the actuator assembly 106 to drive movement of the shaft 110, thereby driving movement of the ram 100. For example, each of the motors 118, 120 may be coupled to the same gear of the first stage 114 of the gear system 112, and each motor 118, 120 may generate a rotational force that causes rotation of the gear. Rotation of the gear may cause rotation and/or revolution of other gears of the first stage 114 of the gear system 112, and the rotation and/or revolution of the gears of the first stage 114 of the gear system 112 may then drive rotation and/or revolution of the gears of the second stage 116 of the gear system 112. The rotation and/or revolution of the gears of the second stage 116 may subsequently drive movement of the shaft 110 along the first axis 108. It should be noted that the motors 118, 120 may each cause rotation of a gear about a second axis 122, which is transverse to the first axis 108. By way of example, the second axis 122 may substantially extend along the second horizontal axis 34 such that the second axis 122 may be oriented at a substantially perpendicular angle relative to the first axis 108.
[0017] Although the illustrated gear system 112 includes two stages, additional or alternative gear systems 112 may include any suitable number of stages, such as one stage, three stages, or four or more stages. For instance, the gear system 112 may include a number of stages based on a desirable amount of force or power generated by the motors 118, 120 to move the shaft 110 (e.g., toward the closed position of the BOP 42), an efficiency of the motors 118, 120 to move the shaft 110, a gear ratio indicative of the extent to which rotation of the motors 118, 120 causes subsequent movement of the shaft 110, another suitable parameter, or any combination thereof. By way of example, an additional or alternative gear system 112 may increase the number of stages in

order to enable the motors 118, 120 to provide a greater force for driving movement of the shaft 110 and the ram 100.
[0018] Moreover, the BOP 42 may include a control system 124 (e.g., an electronic controller) communicatively coupled to the first motor 118 and/or the second motor 120. The control system 124 may include a memory 126 and a processor 128, such as a microprocessor. The memory 126 may include volatile memory, such as random-access memory (RAM), and/or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, solid-state drives, or any other non-transitory computer-readable medium that includes instructions to operate the motors 118, 120. The processor 128 may be configured to execute instructions stored on the memory 126 to control operation of the motors 118, 120. For example, the processor 128 may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof, to operate the motors 118, 120. While only the ram 100 and its actuator assembly 106 are shown in FIG. 2 to facilitate discussion, it should be appreciated that another ram with a respective actuator assembly may be provided on the opposite side of the central bore 28.
[0019] FIG. 3 is a partial side cross-sectional view of an embodiment of the actuation system 106 having the gear system 112. The gear system 112 may include a first gear 150 of the first stage 114. The first gear 150 may be configured to couple to the first motor 118 and/or the second motor 120. As an example, the first gear 150 may be a worm gear (e.g., a straight worm gear or a cone worm gear), a bevel gear, a herringbone gear, a helical gear, or any combination thereof, configured to rotate about the second axis 122. The first gear 150 may be mechanically engaged with a second gear 152 of the first stage 114. The second gear 152 may be a ring gear that extends circularly around the first axis 108 (e.g., in the circumferential direction 36; around the shaft 110). Rotation of the first gear 150 about the second axis 122 may cause rotation of the second gear 152 about the first axis 108. The second gear 152 may be mechanically engaged with one or more third gears 154, which may each be a

planetary gear (e.g., a straight spur gear or a helical gear). The one or more third gears 154 may circularly extend around and may be configured to rotate about a respective third axis 156 (e.g., extending along the first horizontal axis 32). For instance, the third gear(s) 154 may be rotatably coupled to a pin 158 via a bearing 160 (e.g., an axial bearing, a radial bearing, a combined bearing) in order to rotate about the pin 158 and the respective third axis 156. The pin 158 may be fixedly coupled to the enclosure via one or more fasteners (e.g., bolts). The third gear(s) 154 may be mechanically engaged with a fourth gear 162, which may be a sun gear. The fourth gear 162 may circularly extend around the first axis 108 (e.g., in the circumferential direction 36; around the shaft 110), and rotation of the third gear(s) 154 may cause rotation of the fourth gear 162 about the first axis 108. Further, the fourth gear 162 may be rotationally coupled to the shaft 110 via a bearing 164. The bearing 164 enables the fourth gear 162 to rotate about the first axis 108 without directly causing the shaft 110 to rotate. Rather, rotation of the fourth gear 162 may cause rotation of the gears of the second stage 116.
[0020] For example, the fourth gear 162 may extend from the first stage 114 to the second stage 116 to mechanically engage with one or more fifth gears 166, which may each be a planetary gear. Each fifth gear 166 may circularly extend around a respective fourth axis 168 (e.g., extending along the first horizontal axis 32). Rotation of the fourth gear 162 about the first axis 108 may cause rotation of each fifth gear 166 about the respective fourth axis 168. Each fifth gear 166 may also be coupled to a sixth gear 170, which may be a ring gear circularly extending around the first axis 108 (e.g., in the circumferential direction 36; around the shaft 110). The sixth gear 170 may be fixedly coupled to the enclosure 104 (e.g., via one or more fasteners, such as bolts) such that the sixth gear 170 may remain substantially stationary relative to the enclosure 104 during operation of the gear system 112.
[0021] Accordingly, rotation of each fifth gear 166 about the respective fourth axis 168 may cause the fifth gear(s) 166 to revolve around the first axis 108. Each fifth gear(s) 166 may be coupled to a planet carrier 172, which may be a carrier of the second stage 116. By way of example, the planet carrier 172 may

include one or more extensions 174 that are each configured to rotatably couple to one of the fifth gears 166 via a bearing 176. The bearing 176 may enable the fifth gear(s) 166 to rotate about the fourth axes 168 without causing rotation of the extension(s) 174 about the respective fourth axes 168. However, revolution of the fifth gear(s) 166 about the first axis 108 may cause revolution of the extension(s) 174 about the first axis 108. The revolution of the extension(s) 174 about the first axis 108 may then drive rotation of an engagement portion 178 (e.g., annular portion) of the planet carrier 172 about the first axis 108. The engagement portion 178 may be threadably coupled to the shaft 110, and the rotation of the engagement portion 178 about the first axis 108 may cause movement of the shaft 110 in an axial direction along the first axis 108.
[0022] Accordingly, rotation of the first gear 150, as caused by the first motor 118 and/or by the second motor 120, causes rotation of the engagement portion 178 to drive movement of the shaft 110 along the first axis 108. Indeed, the first motor 118 and/or the second motor 120 may operate to rotate the first gear 150 in a first rotational direction about the second axis 122 to drive the shaft 110 in a first direction 180 (e.g., toward the central bore 28, toward the closed position). The first motor 118 and/or the second motor 120 may also operate to rotate the first gear 150 in a second rotational direction about the second axis 122 to drive the shaft 110 in a second direction 182, opposite the first direction 180 (e.g., away from the central bore 28, toward the open position).
[0023] It should be noted that any of a variety of components may be utilized as part of the gear system 112. As an example, different gears may be fixed and movable (e.g., the sixth gear 170 may be movable relative to the enclosure 104, and the fifth gear(s) 166 may be fixedly coupled to the sixth gear 170). As another example, a different type of carrier (e.g., a ball screw type that does not have the extensions 166) may be used to drive movement of the shaft 110. Additional components may also be used to facilitate operation of the gear system 112. In an example, hydraulic actuation may be used to provide an additional force to move the shaft 110. In another example, sensors (e.g., a position sensor, a pressure sensor) may be used to facilitate operation of the

actuation system 106. Such sensors may be communicatively coupled to the control system 124 and may provide data that may be used by the control system 124 to operate the motors 118, 120, for instance.
[0024] While the disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the following appended claims.
[0025] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as "means for [perform]ing [a function]..." or "step for [perform]ing [a function]...", it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

I/We Claim:
1. An actuator assembly for a blowout preventer (BOP), the actuator assembly comprising:
a motor;
a threaded shaft configured to couple to a ram of the BOP; and
a gear system comprising a plurality of gear stages;
wherein the motor is mechanically engaged with a first gear stage of the plurality of gear stages, the threaded shaft is mechanically engaged with a second gear stage of the plurality of gear stages, and the motor is configured to drive a first gear of the first gear stage to rotate about a first axis to thereby cause the first gear stage and the second gear stage to drive the threaded shaft to move along a second axis transverse to the first axis.