Patent Description:
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.

<CIT> describes a blowout preventer including a main body, a bonnet movably connected to the main body, the bonnet having a bonnet channel with interior threading, a ram shaft with a first portion extending through the main body and a second portion extending through the bonnet. The ram shaft has a channel therein, a ram connected to the ram shaft for selectively engaging a pipe and a locking assembly for selectively locking the ram shaft. The locking assembly includes a torquing shaft with a portion within the ram shaft channel, the torquing shaft having an external end projecting beyond the bonnet. A locking shaft is secured to the torquing shaft and has an exterior threading for threadedly engaging the interior threading of the bonnet channel. The locking shaft is rotatable within the bonnet channel to abut an outer end of the ram shaft so as to releasably lock the ram shaft in position.

Various features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein:.

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.

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. The first ram may include a first threaded opening to receive a first threaded shaft, and the second ram may include a second threaded opening to receive a second threaded shaft. The first threaded shaft may be coupled to and driven to rotate by a first motor (e.g., electric motor, hydraulic motor), and the second threaded shaft may be coupled to and driven to rotate by a second motor (e.g., electric motor, hydraulic motor). In operation, rotation of the first and second threaded shafts by the first and second motors causes 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, in some embodiments, a single motor (e.g., electric motor, hydraulic motor) may rotate both the first and second threaded shafts to 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. The disclosed embodiments may provide a compact BOP that is also pressure-balanced to reduce power consumption, for example.

While the disclosed embodiments are described in the context of a drilling system and drilling operations to facilitate discussion, it should be appreciated 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 tool 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.

With the foregoing in mind, <FIG> is a block diagram of an embodiment of a mineral extraction system <NUM>. The mineral extraction system <NUM> 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 <NUM> 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 <NUM> (e.g., BOP stack) is mounted to a wellhead <NUM>, which is coupled to a mineral deposit via a wellbore <NUM>. The wellhead <NUM> may include any of a variety of other components such as a spool, a hanger, and a "Christmas" tree. The wellhead <NUM> may return drilling fluid or mud toward the surface <NUM> during drilling operations, for example. Downhole operations are carried out by a conduit <NUM> (e.g., drill string) that extends through a central bore <NUM> (e.g., flow bore) of the BOP assembly <NUM>, through the wellhead <NUM>, and into the wellbore <NUM>.

To facilitate discussion, the BOP assembly <NUM> and its components may be described with reference to a vertical axis or direction <NUM>, a first horizontal axis or direction <NUM> (e.g., axial axis or direction), a second horizontal axis or direction <NUM> (e.g., lateral axis or direction), and a circumferential axis or direction <NUM> (e.g., about the first horizontal axis <NUM>). The BOP assembly <NUM> may include one or more BOPs <NUM> stacked along the vertical axis <NUM> relative to one another. One or more of the BOPs <NUM> may include opposed rams that are configured to move along the first horizontal axis <NUM> toward and away from one another to adjust the BOP <NUM> between an open position and a closed position. In the open position, the BOP <NUM> may enable fluid flow through the central bore <NUM>. In the closed position, the BOP <NUM> may block fluid flow through the central bore <NUM>.

The BOP assembly <NUM> may include any suitable number of the BOPs <NUM> (e.g., <NUM>, <NUM>, <NUM>, <NUM>, or more BOPs <NUM>). Additionally, the BOP assembly <NUM> may include any of a variety of different types of BOPs <NUM> (e.g., having shear rams, blind rams, blind shear rams, pipe rams). For example, in certain embodiments, the BOP assembly <NUM> may include one or more BOPs <NUM> having opposed shear rams or blades configured to sever the conduit <NUM> to block fluid flow through the central bore <NUM> and/or one or more BOPs <NUM> having opposed pipe rams configured to engage the conduit <NUM> to block fluid flow through the central bore <NUM> (e.g., through an annulus about the conduit <NUM>). The disclosed embodiments include BOPs <NUM> having various features, such as threaded openings in the rams and corresponding threaded shafts that rotate within the threaded openings to drive the rams toward and away from one another to adjust the BOP <NUM> between the open position and the closed position.

<FIG> is a top cross-sectional view of an embodiment of one BOP <NUM> in an open position <NUM>. As noted above, in the open position <NUM>, the BOP <NUM> may enable fluid flow through the central bore <NUM> (e.g., through an annulus between the conduit <NUM> and a wall defining the central bore <NUM>). In the open position <NUM>, a first ram <NUM> and a second ram <NUM> are withdrawn into cavities and retracted from the central bore <NUM>, do not contact the conduit <NUM>, and/or do not contact the opposing ram <NUM>, <NUM>.

As shown, the BOP <NUM> includes a housing <NUM> (e.g., body). A first bonnet <NUM> is coupled to a first end of the housing <NUM> (e.g., via threaded fasteners, such as bolts), and a second bonnet <NUM> is coupled to a second end of the housing <NUM> (e.g., via threaded fasteners, such as bolts). The first bonnet <NUM> supports a first actuator assembly <NUM>, and the second bonnet <NUM> supports a second actuator assembly <NUM>. As described in more detail below, the first actuator assembly <NUM> and the second actuator assembly <NUM> may drive the first ram <NUM> and the second ram <NUM>, respectively, toward and away from one another along the first horizontal axis <NUM> to adjust the BOP <NUM> between the open position <NUM> and a closed position.

In the illustrated embodiment, the first ram <NUM> and the second ram <NUM> each include a respective ram body <NUM> and a respective packer assembly <NUM>. The first ram <NUM> and the second ram <NUM> may each include a forward edge <NUM> (e.g., sealing edge, conduit-contacting edge), a rearward edge <NUM> opposite the forward edge <NUM>, a first side edge <NUM>, and a second side edge <NUM> opposite the first side edge <NUM>. Each packer assembly <NUM> may include one or more forward packer segments <NUM> positioned along the forward edge <NUM> to engage and seal against the conduit <NUM>. The one or more forward packer segments <NUM> positioned along the forward edge <NUM> of the first ram <NUM> may additionally or alternatively seal against the one or more forward packer segments <NUM> positioned along the forward edge <NUM> of the second ram <NUM>. Each packer assembly <NUM> may also include one or more side packer segments <NUM> positioned along the first side edge <NUM> and the second side edge <NUM>, as well as one or more top packer segments <NUM> positioned along an upper surface of the body <NUM> and extending laterally between the first side edge <NUM> and the second side edge <NUM>. It should be appreciated that one or more of the segments <NUM>, <NUM>, <NUM> of the packer assembly <NUM> may formed as a unitary or one-piece structure, and the packer assembly <NUM> may have any of a variety of configurations to enable the BOP <NUM> to form appropriate seals to block fluid flow through the central bore <NUM> while the BOP <NUM> is in the closed position.

In the illustrated embodiment, the first ram <NUM> and the second ram <NUM> each include an opening <NUM> (e.g., threaded opening or recess) formed in the rearward edge <NUM>. Each opening <NUM> is configured to receive a respective shaft <NUM> (e.g., threaded shaft), which may be driven to rotate by a respective motor <NUM> (e.g., electric motor, hydraulic motor). The first actuator assembly <NUM> and the second actuator assembly <NUM> may each include one shaft <NUM>, one motor <NUM>, as well as a bearing <NUM>.

With reference to the first ram <NUM> and the first actuator assembly <NUM>, the motor <NUM> may be controlled (e.g., via an electronic controller) to generate a rotational force that causes rotation of the shaft <NUM> (e.g., in the circumferential direction <NUM> or in a direction opposite the circumferential direction <NUM>). The shaft <NUM> is blocked from moving axially relative to the housing <NUM> (e.g., via attachment at the motor <NUM>). As a result of this configuration, rotation of the shaft <NUM> causes the first ram <NUM> to move linearly along the shaft <NUM> and along the first horizontal axis <NUM> between the illustrated open position <NUM> and the closed position. For example, rotation of the shaft <NUM> in a first direction (e.g., in the circumferential direction <NUM>) may cause the first ram <NUM> to move linearly along the first horizontal axis <NUM> toward the closed position, while rotation of the shaft <NUM> in a second direction (e.g., a direction opposite the circumferential direction <NUM>) may cause the first ram <NUM> to move linearly along the first horizontal axis <NUM> toward the open position <NUM>.

Also with reference to the first ram <NUM> and the first actuator assembly <NUM>, the shaft <NUM> is supported by the bearing <NUM>. In operation, pressure from the central bore <NUM> (e.g., wellbore pressure) may drive the shaft <NUM> in the first horizontal direction <NUM> away from the central bore <NUM>. For example, fluid at pressure from the central bore <NUM> may travel under and/or around the first ram <NUM> to exert a force on the shaft <NUM> that drives the shaft <NUM> in the first horizontal direction <NUM> away from the central bore <NUM>. However, in the illustrated embodiment, the shaft <NUM> may be driven against the bearing <NUM>, which is positioned between a flange <NUM> of the shaft <NUM> and a support surface <NUM> (e.g., a surface of a housing of the motor <NUM> or other axially-facing surface). The bearing <NUM> absorbs the pressure end load exerted by the pressure on the shaft <NUM> and facilitates rotation of the shaft <NUM>. As a result of this pressure-balanced configuration, the motor <NUM> may need to provide less power to drive rotation of the shaft <NUM> (e.g., as compared to a configuration without the bearing <NUM>), which in turn may facilitate use of an electric motor as the motor <NUM> and/or enable use of a smaller motor <NUM>. Furthermore, using the electric motor as the motor <NUM> and controlling the electric motor with an electronic controller may simplify and/or provide for more precise operation of the BOP <NUM>. The illustrated BOP <NUM> includes a seal <NUM> (e.g., annular seal) that seals between the first bonnet <NUM> and the shaft <NUM>.

The second ram <NUM> and the second actuator assembly <NUM> may include the same components and same operational features. Additionally, while the illustrated BOP <NUM> is a pipe ram with pipe rams <NUM>, <NUM> that are configured to engage the conduit <NUM>, it should be appreciated that the BOP <NUM> may be another type of ram (e.g., shear ram) and include other types of rams (e.g., shear rams with blades that shear the conduit <NUM>).

<FIG> is a top cross-sectional view of the BOP <NUM> in a closed position <NUM>. As noted above, in the closed position <NUM>, the BOP <NUM> may block fluid flow through the central bore <NUM> (e.g., through the annulus between the conduit <NUM> and the wall defining the central bore <NUM>). In the closed position <NUM>, the first ram <NUM> and the second ram <NUM> protrude from the cavities and extend into the central bore <NUM>, contact the conduit <NUM>, and/or contact the opposing ram <NUM>, <NUM>.

As discussed above, to adjust the BOP <NUM> from the open position <NUM> shown in <FIG> to the closed position <NUM> shown in <FIG>, each motor <NUM> may be controlled to generate a rotational force that causes rotation of the respective shaft <NUM> (e.g., in the circumferential direction <NUM> or in a direction opposite the circumferential direction <NUM>). Rotation of the shaft <NUM> of the first actuator assembly <NUM> causes the first ram <NUM> to move linearly along the first horizontal axis <NUM> toward the second ram <NUM>, and rotation of the shaft <NUM> of the second actuator assembly <NUM> causes the second ram <NUM> to move linearly along the first horizontal axis <NUM> toward the first ram <NUM>. The first ram <NUM> and the second ram <NUM> may be driven linearly toward one another until the first ram <NUM> and the second ram <NUM> block fluid flow through the central bore <NUM> (e.g., engage the conduit <NUM> to block the fluid flow through the annulus about the conduit <NUM>). As shown in <FIG>, while the BOP <NUM> is in the closed position <NUM>, the shaft <NUM> extends into and remains threaded only to an end portion of the opening <NUM> of the respective ram <NUM>, <NUM> (e.g., a smaller portion or axial length of the opening <NUM> than when the BOP <NUM> is in the open position <NUM>).

<FIG> is an end view (e.g., of the rearward end <NUM>) of an embodiment of the first ram <NUM>, wherein the first ram <NUM> is generally cylindrical with a generally circular cross-sectional shape (e.g., taken in a plane perpendicular to the first horizontal axis <NUM>). As shown, the first ram <NUM> includes the body <NUM> and the packer assembly <NUM>, which is configured to seal against surfaces of the housing <NUM> to block fluid flow through the central bore <NUM> while the BOP <NUM> is in the closed position <NUM>. The opening <NUM> is formed in the rearward end <NUM> of the first ram <NUM> to receive the shaft <NUM>.

In the illustrated embodiment, an alignment interface <NUM> (e.g., key-slot interface) is provided between the first ram <NUM> and the housing <NUM> to block rotation of the first ram <NUM> relative to the housing <NUM>. For example, as shown, the first ram <NUM> includes an alignment slot <NUM> (e.g., slot) that is configured to receive a protrusion <NUM> (e.g., key) extending from the housing <NUM> (e.g., extending radially-inwardly into a ram-supporting cavity <NUM> defined by the housing <NUM>). As shown, the alignment slot <NUM> extends about a portion of a circumference of the first ram <NUM> (e.g., equal to or less than about <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent of the circumference). The alignment slot <NUM> may extend along the first horizontal axis <NUM> and may extend along all or some of an axial length of the first ram <NUM> (e.g., equal to or greater than about <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent of the axial length). Without the alignment interface <NUM>, the first ram <NUM> may be driven to rotate in response to rotation of the shaft <NUM> due to the generally circular cross-sectional shape of the first ram <NUM>. In some embodiments, the alignment slot <NUM> may serve no purpose other than blocking rotation of the first ram <NUM> relative to the housing <NUM>. While the alignment interface <NUM> is shown along a lowermost portion <NUM> of a lower surface <NUM> that extends laterally between the side edges <NUM>, <NUM> of the first ram <NUM> (e.g., opposite the top packer segment <NUM>) in <FIG>, it should be appreciated that the alignment interface <NUM> may provided at any location that does not interfere with the seal between the packer assembly <NUM> and the housing <NUM> (e.g., at any location along the lower surface <NUM>; a portion of the side edges <NUM>, <NUM> rearward of the side packer segments <NUM>; an upper surface rearward of the top packer segment <NUM>).

The BOP <NUM> may include rams <NUM>, <NUM> having various other cross-sectional shapes (e.g., non-circular). In such cases, the shape of the rams <NUM>, <NUM> and the corresponding shape of the cavities through which the rams <NUM>, <NUM> move may block rotation of the rams <NUM>, <NUM> relative to the housing <NUM>. However, in some embodiments, the alignment interface <NUM> may be provided for additional stability as the rams <NUM>, <NUM> move linearly within cavities defined by the housing <NUM>.

For example, <FIG> is an end view (e.g., of the rearward end <NUM>) of an embodiment of the first ram <NUM>, wherein the first ram <NUM> is generally an elliptic cylinder with a generally oval or elliptical cross-sectional shape (e.g., taken in a plane perpendicular to the first horizontal axis <NUM>). As shown, the first ram <NUM> includes the body <NUM> and the packer assembly <NUM>, which is configured to seal against surfaces of the housing <NUM> to block fluid flow through the central bore <NUM> while the BOP <NUM> is in the closed position <NUM>. The opening <NUM> is formed in the rearward end <NUM> of the first ram <NUM> to receive the shaft <NUM>.

In the illustrated embodiment, the alignment interface <NUM> is provided between the first ram <NUM> and the housing <NUM> to block rotation of the first ram <NUM> relative to the housing <NUM>. For example, as shown, the first ram <NUM> includes two alignment slots <NUM> that are configured to receive protrusions <NUM> extending from the housing <NUM> (e.g., extending radially-inwardly into the ram-supporting cavity <NUM> defined by the housing <NUM>). The alignment slots <NUM> may extend along the first horizontal axis <NUM> and may extend along all or some of an axial length of the first ram <NUM> (e.g., equal to or greater than <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent of the axial length).

While the alignment interface <NUM> includes the alignments slots <NUM> and the protrusions <NUM> along the side edges <NUM>, <NUM> of the first ram <NUM> in <FIG>, it should be appreciated that the alignment interface <NUM> may include alignments slots <NUM> and the protrusions <NUM> at any location that does not interfere with the seal between the packer assembly <NUM> and the housing <NUM> (e.g., the lower surface <NUM>). Furthermore, with reference to <FIG> and <FIG>, it should also be appreciated that the first ram <NUM> may include any suitable number of alignment slots <NUM> (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or more) and the housing <NUM> may include any suitable number of protrusions <NUM> (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or more). It should also be appreciated that, in some embodiments, the first ram <NUM> may include one or more protrusions <NUM> and the housing <NUM> may include one or more alignment slots <NUM>. Additionally, the second ram <NUM> may include similar features to block rotation of the second ram <NUM> relative to the housing <NUM>.

<FIG> is a top cross-sectional view of an embodiment of the BOP <NUM> having two rams <NUM>, <NUM> driven by one motor <NUM>. The motor <NUM> may be controlled to generate a rotational force that causes rotation of a drive shaft <NUM> (e.g., in the circumferential direction <NUM> or in a direction opposite the circumferential direction <NUM>). Rotation of the drive shaft <NUM> may cause rotation of the shaft <NUM> coupled to the first ram <NUM> and the shaft <NUM> coupled to the second ram <NUM> to drive the first ram <NUM> and the second ram <NUM> linearly along the first horizontal axis <NUM>.

Various drive mechanisms may be utilized to enable rotation of the drive shaft <NUM> to drive rotation of the shafts <NUM>. For example, chain drives <NUM> may be utilized to enable rotation of the drive shaft <NUM> to drive rotation of the shafts <NUM>. In the illustrated embodiment, gears <NUM> (e.g., sprocket gears) may be coupled (e.g., non-rotatably coupled) to the drive shaft <NUM> and gears <NUM> (e.g., sprocket gears) may be coupled (e.g., non-rotatably coupled) to the shafts <NUM>. Drive chains <NUM> (e.g., roller chains) may be looped around teeth of the gears <NUM> and teeth of the gears <NUM>. Thus, rotation of the drive shaft <NUM> and the attached gears <NUM> pulls the drive chains <NUM>, which causes the gears <NUM> and the attached shafts <NUM> to rotate.

To facilitate moving the first ram <NUM> and the second ram <NUM> toward and away from one another, the threads of the shafts <NUM> may be oriented in opposite directions (e.g., threads of the shaft <NUM> that is coupled to the first ram <NUM> are right-handed threads and threads of the shaft <NUM> that is coupled to the second ram <NUM> are left-handed threads, or vice versa). As noted above, various drive mechanisms may be utilized to enable rotation of the drive shaft <NUM> to drive rotation of the shafts <NUM>. For example, bevel gears may be utilized to enable rotation of the drive shaft <NUM> to drive rotation of the shafts <NUM>. In such cases, the drive chains <NUM> may be replaced with a shaft having bevel gears on both ends (e.g., at the locations of the illustrated gears <NUM>, <NUM>), and these bevel gears may engage corresponding bevel gears on the drive shaft <NUM> and the shaft <NUM>.

Claim 1:
An assembly (<NUM>) for a blowout preventer, comprising:
a first ram (<NUM>) comprising a first threaded opening (<NUM>);
a first threaded shaft (<NUM>) configured to engage the threaded opening (<NUM>); and characterized by
a motor (<NUM>) configured to drive rotation of the first threaded shaft (<NUM>), wherein rotation of the first threaded shaft (<NUM>) causes the first ram (<NUM>, <NUM>) to move axially along the first threaded shaft (<NUM>).