Electric annular system and method for use in blowout preventer

A technique facilitates reliable operation of a blowout preventer (BOP) system in a wide range of challenging environments. To enable dependable and rapid closing of the internal passageway of the BOP system, an annular closing system is employed. The annular closing system is fully electrically actuated and may comprise a variety of components which cooperate to provide reliable sealing of the internal passageway. Examples of those components comprise a packer which may be compressed inwardly to seal off flow along the interior passage. Additionally, a pusher mechanism is positioned in the annular closing system and is linearly shiftable such that its linear motion causes the packer to be compressed in the radially inward direction. Electrically operated linear actuators are positioned and selectively actuatable to shift the pusher mechanism linearly when causing compression of the packer.

BACKGROUND

In many oil and gas well applications, various types of equipment may be used to contain and isolate pressure in the wellbore. For example, a blowout preventer system may be installed on a wellhead to protect against blowouts. The blowout preventer has a longitudinal interior passage which allows passage of pipe, e.g. drill pipe, and other well components. Additionally, the blowout preventer has a variety of features including rams, e.g. pipe rams and shear rams, which facilitate rapid well sealing operations. Control over operation of the blowout preventer generally is achieved with various types of hydraulic controls. However, as deeper subsea wells and other types of deep wells are developed, the blowout preventer systems are required to operate in more challenging environments while at the same time improving operational availability. These challenging environments and increased requirements can render the hydraulic operating system susceptible to failure.

SUMMARY

In general, a system and method facilitate reliable operation of a blowout preventer (BOP) system in a wide range of challenging environments. To enable dependable and rapid closing of the internal passageway of the BOP system, an annular closing system is employed. The annular closing system is fully electrically actuated and may comprise a variety of components which cooperate to provide reliable sealing of the internal passageway. Examples of those components comprise a packer which may be compressed inwardly to seal off flow along the interior passage. Additionally, a pusher mechanism is positioned in the annular closing system and is linearly shiftable such that its linear motion causes the packer to be compressed in the radially inward direction. Electrically operated linear actuators are positioned and selectively actuatable to shift the pusher mechanism linearly when causing compression of the packer.

DETAILED DESCRIPTION

The disclosure herein generally involves a system and method which facilitate reliable operation of a blowout preventer (BOP) system in a wide range of challenging environments. For example, the BOP system may be employed in various challenging surface environments and subsea environments where the BOP system is used to seal, control, and monitor a hydrocarbon well. Reliable operation in these types of environments is enhanced by constructing the BOP system as an electrically actuated system. This further allows well operators to move away from traditional, hydraulically powered BOP equipment.

To enable dependable and rapid closing of an internal passageway of the BOP system, an electronically actuated annular closing system is employed. The annular closing system may be actuated solely by electrical power without hydraulic actuation. Accordingly, the annular closing system utilizes a variety of components which cooperate to provide the reliable sealing of the internal passageway upon appropriate electrical input. Examples of those components comprise a packer which may be compressed inwardly to seal off flow along the interior passage. Additionally, a pusher mechanism is positioned in the annular closing system and is linearly shiftable such that its linear motion causes the packer to be compressed in the radially inward direction. Electrically operated linear actuators are positioned and selectively actuatable to shift the pusher mechanism linearly when causing compression of the packer.

In a specific embodiment, the electric annular closing system comprises a body containing the packer with a donut surrounding the packer. By way of example, the donut may be made from a suitable elastomeric material. A pusher mechanism, e.g. a pusher plate, is positioned within the annular closing system body such that linear movement of the pusher mechanism squeezes the donut. The linear movement may be in a direction generally parallel with an axis along the internal passageway of the BOP system. As the donut is squeezed by the pusher mechanism, the elastomeric material is forced inwardly which causes the packer to be compressed in a radially inward direction. Upon sufficient movement of the pusher mechanism, the packer is transitioned to a fully sealed position blocking flow along the internal passageway.

An array of electrically operated linear actuators is positioned within the body and is actuatable to move the pusher plate linearly. By way of example, each of the electrically operated linear actuators may comprise a linear operator, e.g. a plunger/piston, which may be moved linearly upon application of electrical power. The linear operator may be moved in a direction generally parallel with the axis of the internal passageway.

Referring generally toFIG.1, a well system30is illustrated as comprising a BOP system32for providing pressure control at a well34. In this example, the BOP system32is mounted on a wellhead36, e.g. a land-based wellhead or a subsea wellhead, located above a borehole38, e.g. a wellbore. The BOP system32may be arranged as a BOP stack40and may comprise a variety of BOP components, such as ram BOPs42and an annular closing system44. By way of example, the ram BOPs42may comprise pipe rams and shear rams. Additionally, the annular closing system44may be mounted above the ram BOPs42. As described below, the BOP system32may have a central, longitudinal passage for receiving tubular components45, e.g. drill pipe or other pipe, therethrough. The annular closing system44is in the form of an electronically actuated annular closing system.

Referring generally toFIG.2, one example of electronic annular closing system44is illustrated as being electrically actuatable via an array of electrically operated linear actuators46. According to the example illustrated, the annular closing system44comprises a body48which forms the outer structure that supports components of annular closing system44. The electrically operated linear actuators46are mounted within body48via suitable mounting structures50, such as an internal mounting plate structure52and an external mounting ring54. The internal mounting plate structure52may be secured to body48via fasteners56or other suitable mounting mechanisms. The external mounting ring54may be secured between the array of linear actuators46and a surrounding internal wall58of body48.

In this particular embodiment, a pusher mechanism60is secured to the array of electrically operated linear actuators46. For example, the pusher mechanism60may be secured to actuatable components of the linear actuators46via threaded fasteners62or other suitable securing mechanisms. In some embodiments, the pusher mechanism60may be in a form of a pusher plate64which extends across the array of linear actuators46and around a central passageway66. It should be noted the central passageway66is a continuation of the internal passageway extending through BOP system32.

In the illustrated example, the pusher plate64is linearly slidable in a direction generally parallel with an axis68of central passageway66while being secured radially between a packer mounting plate70and a top72. The top72may be secured to body48via, for example, an actuator ring74or other suitable fastening mechanism. The packer mounting plate70may be secured within body48via fasteners56or other suitable mechanisms.

The top72cooperates with body48to secure a packer76therein above packer mounting plate70. Packer76may have a variety of configurations, but one example utilizes a combination of an elastomeric sealing portion78and a metal portion80, e.g. a steel portion, formed by packer inserts82and/or other packer supporting structures, as further illustrated inFIG.3. In the illustrated embodiment, packer76is surrounded by a donut84which may be formed of an elastomeric material or other suitable material which helps form a secure seal within the annular closing system44.

As illustrated, the pusher mechanism60, e.g. pusher plate64, is movably positioned between the array of electrically operated linear actuators46and the donut84. Additionally, the donut84is constrained via an internal wall86of top72. Accordingly, when linear actuators46are actuated to move pusher mechanism60in a linear direction, e.g. parallel with axis68, the elastomeric donut84is squeezed.

This squeezing action within the constraints of internal wall86causes the donut84to expand radially inwardly and to thus drive the packer76in a radially inward direction. Upon sufficient squeezing of donut84, the packer76is forced to a set, sealed position against tubular45or to a sealed position within an empty central passageway66. Regardless, flow along central passageway66is blocked once the packer76is actuated to the set/closed position.

It should be noted the electronic annular closing system44may be connected to various other components which may be part of the overall BOP system32. Accordingly, the electronic annular closing system44may comprise mounting features88constructed for coupling with adjacent components. Examples of mounting features88include flanges90and mounting studs/bolts92.

Referring generally toFIG.4, an example of one of the electrically operated linear actuators46is illustrated. In this embodiment, the linear actuator46may be in the form of an electromagnetic actuator94, such as a “railgun” type of electrically operated linear actuator. One example of this type of electromagnetic “railgun” linear actuator94comprises a plurality of, e.g. two, parallel metal rails96with a plunger/piston98located between the rails96.

When an electric current is applied to the metal rails96a magnetic field is created. Electric current flows through one rail96and returns from the opposite rail96through the plunger/piston98, as illustrated by current path100. As further illustrated inFIG.4, the current direction across plunger/piston98is represented by arrow102and the direction of the created magnetic field is represented by arrow104. As a result of this created magnetic field, a force is generated on the plunger/piston98in the direction of arrow106.

Effectively, the magnetic field or fields are electromagnetic fields which generate a Lorentz force that accelerates the plunger/piston98in direction106. The Lorentz forces are directed perpendicularly to the magnetic field (arrow104) and perpendicularly to the direction of current flowing across the plunger/piston98(arrow102). The strength of this Lorentz propulsion force on plunger/piston98can be found using the equation: F−Il×B. In this equation, F is the strength of the Lorentz propulsion force; I represents the amount of current; l represents the distance between the rails96; and B represents the quality and magnitude of the magnetic field.

As electric current is applied to the metal rails96of the array of electrically operated linear actuators46, the plungers/pistons98are collectively moved in direction106. This linear movement forces the pusher mechanism60in a corresponding linear movement so as to compress donut84. As described above, the squeezing of donut84in this linear direction combined with the constraint provided by walls86forces the donut84to expand in a radially inward direction, thus forcing actuation of packer76in this radially inward direction.

The force applied to pusher mechanism60(and ultimately to packer76) is further affected by the number of electrically operated linear actuators46in the overall array. By way of example, there may be two linear actuators46; four linear actuators46; six linear actuators46; or other suitable number of linear actuators46to achieve the desired actuation of packer76. If space and power permits, even greater numbers of linear actuators46, e.g. 10 or more linear actuators46, may be employed. As illustrated, the electrically operated linear actuators46may be arranged within body48and circumferentially around central passageway66.

Use of electrically operated linear actuators46allows entirely electric actuation of packer76. This fully electric system enables construction of the system without use of hydraulic actuator components or other types of non-electric actuator components.

Additionally, the type of structure described herein enables actuation of packer76with no mechanical components directly connected to the donut84or packer assembly76, thus allowing central passageway66to open freely during, for example, stripping operations. Simple electrical actuation enables dependable, controlled squeezing or relaxing of the donut84and packer76so as to close off or open up the central passageway66.

Depending on the specific well operation, well environment, and well equipment, the overall well system30may be adjusted and various configurations may be employed. For example, the BOP system32may comprise many types of alternate and/or additional components. Additionally, the BOP system32may be combined with many other types of wellheads and other well components used in, for example, land-based or subsea hydrocarbon production operations.

Furthermore, the components and arrangement of annular closing system44may vary according to the parameters of a given environment and/or well operation. For example, the electric actuation may be achieved by various numbers and arrangements of electrically operated linear actuators46. The linear actuators46may be coupled with various types of pusher mechanisms60for engaging suitable types of donuts84. Some embodiments may be constructed without the donut84such that the pusher mechanism60engages packer76directly or through other types of mechanisms. Additionally, packer76may have different types, sizes and configurations of elastomeric components, metal components, or other types of components to achieve the desired sealing.