Abstract: Apparatuses useable in drilling installations for adjusting a mud return flow in a mud loop, at a location far from a mud tank are provided. An apparatus includes (1) a sensor located close to a seabed and configured to acquire values of at least one parameter related to a return mud flow, (2) a valve located near the sensor and configured to regulate the return mud flow, and (3) a controller connected to the valve and the sensor. The controller is configured to automatically control the valve to regulate the return mud flow towards achieving a value of a control parameter close to a predetermined value, based on the values acquired by the sensor. Methods of incorporating an apparatus in a drilling installation and retrofitting existing installations are also provided.

Abstract: A blowout preventer comprising: a main body comprising a seal seating profile, one or more bonnet guideways, and one or more slide guideways; a bonnet attached to the main body, wherein the bonnet comprises one or more guide rods, a ram unit, and a seal seating profile; two retention units attached to the main body and the bonnet, wherein each retention unit comprise a clamp block, one or more guide rods, and a bonnet guideway; and a metal seal, wherein the metal seal is seated in the seal seating profile of the main body and the seal seating profile of the bonnet.

Abstract: A lock for a ram shaft of a blowout preventer has a ram shaft controlled by an actuator, the ram shaft having a ram block end and a locking end, the locking end having an internal cavity that extends along an axis of the ram shaft, and a locking pin in the internal cavity. The locking pin has a release position retracted into the internal cavity, and a locking position extending from the internal cavity. A rotational stop engages the ram shaft and prevents the ram shaft from rotating. A locking pin stop is secured relative to the actuator, the locking pin stop engaging the locking pin in the locking position to prevent axial movement of the ram shaft.

Abstract: A blowout preventer having a body, a main bore in the body, and rams that project into the main bore. The rams can be shear rams for shearing a tubular in the main bore, pipe rains for sealing around a tubular in the main bore, or sealing rams that seal across the main bore. The rams are in cavities formed in the body, the cavities are formed such that more than two rams can be disposed at the same elevation in the body thereby reducing the overall height of the blowout preventer stack.

Abstract: Method, ram block and ram blowout preventer (BOP) for sealing a well. The BOP includes a body having a first chamber extending along a first direction and a second chamber extending along a second direction, substantially perpendicular to the first direction; a ram block configured to move inside the first chamber, the ram block having a packer region and at least one channel that extends all the way through the ram block; a packer configured to be provided in the packer region to seal a tool provided inside the second chamber; and at least one double piston provided through the at least one channel so that a pressure from the well is transmitted to the packer.

Abstract: A status assembly to provide visual and electronic indication of the position (open, closed, in-between) of the ram of a ram-type blowout preventer (BOP). The assembly is capable of coupling with a hydraulic motor that can be used to open and close the ram locks. The status assembly includes a rotatable element protruding from the BOP, a gear rotatable by the rotatable element, and an indicator that indicates the rotation position of the rotatable element and thus the linear position of the BOP ram. Some embodiments can also include a sensor that outputs an electronic signal to the system operator and can be incorporated into the main display for the BOP control system. This device is able to give immediate feedback to operators and to indicate whether each ram has achieved its intended travel.

Abstract: A blowout preventer for sealing a tubular of a wellbore is provided. The blowout preventer has a housing having a bore therethrough for receiving the tubular, at least one ram slidably positionable in the housing (each of the rams having a ram block for sealing engagement about the tubular), an actuator for selectively driving the ram block (the actuator comprising a piston slidably positionable in a cylinder), and a monitor for detecting the piston therein. The monitor has a visual indicator on an exterior of the cylinder. The visual indicator is operatively coupled to the piston for displaying a position of the piston as the piston travels within the cylinder whereby a position of the ram may be determined.

Abstract: The present disclosure relates to seals and sealing arrangements, especially those used in wireline valves. The seal comprises an elastomeric seal body with a sealing surface, a plurality of generally planar inserts embedded within the elastomeric seal body adjacent the sealing surface, and having elastomeric seal material disposed between the plurality of generally planar inserts. The generally planar inserts may have a slightly wedge shape and may be embedded into the elastomeric seal body in a generally fan-shaped orientation. They may be orientated such that upon contacting a substantially tubular shaped body to be sealed around and the subsequent deformation of the seal body about said substantially tubular shaped body, the plurality of generally planar inserts become orientated such that they extend radially from the substantially tubular shaped body.

Abstract: A ram-type blowout preventer including an operating piston assembly isolated from wellbore pressure effects is provided. In one embodiment, a blowout preventer includes piston coupled to a ram by a connecting rod, and the connecting rod is inserted into a recess in the ram. A pressure-isolating seal may be provided in the recess between the connecting rod and the ram to isolate the end of the connecting rod within the recess from wellbore pressure in the blowout preventer. Additional systems, devices, and methods are also disclosed.

Abstract: A valve useable in an undersea apparatus for generating a force for closing a blowout preventer (BOP) based on a pressure difference between a low pressure recipient and ambient pressure, an apparatus including the valve and related methods are provided. The valve includes a valve body enclosing a chamber with an input port selectively connectable to an output port, and a chamber separating assembly configured to separate the chamber from a region of different pressure. The assembly includes (1) a backup plate having a first portion of a first diameter towards the chamber and a second portion of a second diameter larger than the first diameter, towards the region, and (2) an upper seat located between the first portion of the backup plate and the valve body.

Abstract: Linear clutches for reducing axial loads in a system are provided. In one embodiment, a system includes a blowout preventer having a ram coupled to an actuation assembly. A locking assembly is positioned within the system to enable an end of the locking sleeve to engage the actuation assembly and to lock the actuation assembly and the ram into place. In this embodiment, the locking sleeve is segmented and includes at least one groove to engage a complementary surface of the actuation assembly. Additional systems, devices, and methods are also disclosed.

Abstract: A ram type blowout preventer having a seal on each ram, extending across the front face, rearwardly and then over the top portion or the bottom portion of the ram. Each ram forms a leading edge portion above or below the front face seal, so as opposing rams move into the extended sealing position, the leading edge portions of the rams press against each other, imparting a generally vertical movement to bring the seals on the front faces into sealing engagement with each other and to energize the seals extending over the top or bottom portions against the ram bores. The front face of each ram may include a portion which is inclined toward the central bore. Rope packing seals may be provided on the rams having a vertical offset at the front faces of the rams such that rope packing seals on opposing front faces seal against each other.

Abstract: A blowout preventer and seal structure for a blowout preventer, the seal structure having a the body with two front faces including a first face and a second face, a projection projecting out from the body, the first face on the projection, the second face in a plane, and the projection with the first face projecting out beyond the plane. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 C.F.R. 1.72(b).

Abstract: A ram shaft assembly is provided. In one embodiment, a system includes a ram actuation assembly of a blowout preventer. The ram actuation assembly can include a ram shaft, one or more mounting members positioned about the ram shaft, and a piston mounted on the one or more mounting members. Additional systems, devices, and methods are also disclosed.

Abstract: A blowout preventer (BOP) is provided in which each ram includes a primary rope packing seal formed from a first length of rope packing extending horizontally across the front face, rearwardly and then either or both of upwardly and downwardly over the top and/or bottom portion of the ram. The primary rope packing seal is held in, so as to protrude radially outwardly from, a continuous first groove formed in the ram. The continuous first groove is adapted to accommodate joined abutting ends or overlapping ends of the first length of rope packing. A secondary rope packing seal and a circumferential rope packing seal may be provided on the ram.

Abstract: A blade assembly of a blowout preventer for shearing a tubular of a wellbore penetrating a subterranean formation is provided. The blowout preventer has a housing with a hole therethrough for receiving the tubular. The blade assembly includes a ram block movable between a non-engagement position and an engagement position about the tubular, a blade carried by the ram block for cuttingly engaging the tubular, a retractable guide carried by the ram block and slidably movable therealong, and a release mechanism for selectively releasing the guide to move between a guide position for guiding engagement with the tubular and a cutting position a distance behind the blade for permitting the blade to cuttingly engage the tubular.

Abstract: A blow out preventer (10) includes a housing (40) defining a longitudinal throughbore (16) and a ram cavity (34) and at least one pair of opposed rams (12, 14) located in the ram cavity. Each ram includes a seal (18, 24) disposed on an upper surface (20, 26) and the rams are movable transversely across the bore. The blow out preventer further includes at least one seal seat (30) having a seal surface (36) for engaging with the ram seals. There is a seal seat associated with each at least one pair of rams, the seal seat being moveably mounted in the ram cavity. In one embodiment the seal seat continuously engages the rams as the rams move from a cavity open position to a cavity closed position.

Abstract: A ram type blowout preventer having a seal on each ram, extending across the front face, rearwardly and then over the top portion or the bottom portion of the ram. Each ram forms a leading edge portion above or below the front face seal, so as opposing rams move into the extended sealing position, the leading edge portions of the rams press against each other, imparting a generally vertical movement to bring the seals on the front faces into sealing engagement with each other and to energize the seals extending over the top or bottom portions against the ram bores. The front face of each ram may include a portion which is inclined toward the central bore. Rope packing seals may be provided on the rams having a vertical offset at the front faces of the rams such that rope packing seals on opposing front faces seal against each other.

Abstract: A sealing apparatus and method is disclosed, particularly for sealing around an elongate member which passes through a throughbore of a valve device, the apparatus having an upper sealing element and a lower sealing element, each being adapted to change configuration from an open configuration to a sealed configuration within the valve device to seal the throughbore of the valve device around the elongate member. The upper and lower sealing elements are separate and moveable independently from one another, and are configured to be actuated between open and sealed configurations by a common actuator. This actuation reduces the stack height and the weight of the valve, and reduces the number of well seals.

Abstract: A shear/seal ram provides a knife edge at the shearing edge and the knife edge is inclined to minimize the cutting force required and to leave a clean cut edge. The knife edge is presented in an opening of the ram, thus the opening is positioned at the axis of the BOP, and consequently the coiled tubing, before the coiled tubing is run through the BOP. A biasing means, such as for example a Bellville spring, forces a sealing sleeve against the underside of the ram to prevent leakage of pressure from below the BOP. Similarly, a plurality of biasing means, referred to herein as “skates”, forces the ram down against the sealing sleeve to seal pressure from above the BOP.

Abstract: A ram-type blowout preventer and method of actuating thereof. The ram-type blowout preventer includes a seal carrier disposed about a vertical bore between the body and adjacent to the horizontal bore. The seal carrier is configured to be thrust into sealing engagement with at least one of a pair of ram blocks of the ram-type blowout preventer by fluid pressure above the ram blocks and a sealing device forms a seal between the body and the seal carrier.

Abstract: A variable bore packer used in a blowout preventer to form a seal against different diameter tubular members for oil and gas drilling operations. The variable bore packer includes a packer member molded of elastomeric material with certain mechanical properties and including an inside curved surface. The packer also includes a plurality of packer inserts molded within the packer member to form an insert array. Additionally, the packer includes a protrusion extending from and bonded to the packer member inside curved surface, the protrusion including increased mechanical properties compared to the packer member. The packer member, the insert array, and the protrusion are molded into a unitary structure and sized to form a seal against the different diameter tubular members upon closure of the blowout preventer. Also, the insert array and the protrusion diminishing extrusion of the elastomeric material between the packer inserts and the tubular members.

Abstract: Methods and apparatuses for severing a wellbore tubular, the apparatus, in certain aspects, including: a first member movable toward a tubular to be severed; a second member with a second blade disposed opposite to the first member and movable toward the tubular; a first blade on the first member having a projection projecting from a center of a blade body with point structure on the projection for puncturing the tubular and cutting surfaces on the projection for cutting the tubular; and cutting surfaces, as needed, on the blade body adjacent the projection for cutting the tubular.

Abstract: The present invention relates to an intervention blowout preventer (1) for being mounted on a well head (2) or a Christmas tree, comprising a plurality of valves (3, 4) arranged in fluid communication with each other, connected and forming a tubular pipe (5) enclosing a cavity being in fluid communication with the well head when the intervention blowout preventer is mounted onto the well head and at least one plug (37) in the well head has been removed, wherein the intervention blowout preventer further comprises a pressure reducing system (1) comprising a chamber (6) and a piston (7) arranged inside the chamber dividing the chamber into a first chamber part (8) and a second chamber part (9), the first chamber part being in fluid communication with the cavity and the second chamber part being filled with a compressible fluid, such as gas. Furthermore, the invention relates to a well intervention tool (100), a well intervention system (200) and a well intervention method.

Abstract: An actuating device for displacing a control device, such as a gate valve or other control mechanism, in particular for use in oil or gas production systems, includes a motor-gear unit and a threaded spindle drive, which is operable by said motor-gear unit. The threaded spindle drive includes at least a threaded spindle and a screw nut. The threaded spindle is displaceable in an essentially axial-direction so as to displace the control device between an advance position and a retracted position. The threaded spindle drive further includes a position holding means holding the attained position of the threaded spindle. The position holding means is directly connected to a motor shaft of the motor-gear unit so as to apply a holding torque to said motor shaft.

Abstract: A shear sealing system of a blowout preventer of a wellbore is provided. The blowout preventer including a housing having a bore and a guideway therethrough. A tubular of the wellbore is positionable in the bore. The shear sealing system includes at least one carriage, at least one blade and at least one seal. The carriages are slidably positionable in the guideway of the blowout preventer. The blades are carried by the carriages and movable thereby between a retracted position and an extended position. The blades are engageable with the tubular when in the extended position. The seal forms a seal about the tubular and with the blade when the blade is in the extended position.

Abstract: A subsea connection apparatus to allow connecting a surface blowout preventer stack and riser to a subsea wellhead is disclosed. The subsea connection apparatus uses a single cavity blowout preventer with a set of shearing blind rams. Hydraulically actuated wellhead connectors are secured to the top and bottom of the blowout preventer to allow connection to a subsea wellhead below the subsea connection apparatus and a well head hub profile on the lower end of a riser above the apparatus. A control system can operate both of the hydraulically actuated connectors and the blowout preventer independently. A frangible bore protector is disposed in the bore of the blowout preventer to protect the shearing blind rams from pipe, tools, and fluids being passed through the blowout preventer and can be sheared by the shearing blind rams along with any drill pipe in the bore.

Abstract: Linear clutches for reducing axial loads in a system are provided. In one embodiment, a system includes a blowout preventer having a ram coupled to an actuation assembly. A locking assembly is positioned within the system to enable an end of the locking sleeve to engage the actuation assembly and to lock the actuation assembly and the ram into place. In this embodiment, the locking sleeve is segmented and includes at least one groove to engage a complimentary surface of the actuation assembly. Additional systems, devices, and methods are also disclosed.

Abstract: Systems are provided for using position data of a piston connected to a ram block in a blowout preventer to determine a backlash of the ram block, and/or to record a position of the ram block, and/or to calculate an instant when a supplemental closing pressure is desired to be applied, and/or to determine when maintenance of a ram locking mechanism is due, and/or to determine when sealing elements are worn.

Abstract: The invention discloses a system and method for controlling a wellbore. The method comprises the steps of: providing a capping stack comprising a number of releasable modules, each module having a size and weight within predetermined limits, wherein said modules include at least one ram type blow out preventer module, and wherein said modules include a connector module for connecting the capping stack to an attachment point of the wellbore; transporting said modules by cargo airplane to a location near the wellbore; interconnecting the modules to provide the capping stack; and connecting the capping stack to the attachment point of the wellbore.

Abstract: An asymmetrical ram button is provided. In one embodiment, a system includes a blowout preventer including such a button. Particularly, the blowout preventer may include an actuation assembly having the asymmetric ram button attached to a connecting rod coupled to a piston. The asymmetric body of the button can engage an internal shoulder of the ram such that a retraction force on the actuation assembly causes the asymmetrical ram button to load against the internal shoulder. Additional systems, devices, and methods are also disclosed.

Abstract: A ram-type blowout preventer including an operating piston assembly isolated from wellbore pressure effects is provided. In one embodiment, a blowout preventer includes piston coupled to a ram by a connecting rod, and the connecting rod is inserted into a recess in the ram. A pressure-isolating seal may be provided in the recess between the connecting rod and the ram to isolate the end of the connecting rod within the recess from wellbore pressure in the blowout preventer. Additional systems, devices, and methods are also disclosed.

Abstract: A pair of shear blades and a blowout preventer having the pair of shear blades. The shear blades are configured to cut a tubular inside the blowout preventer. The shear blades have different geometries of the front cutting surfaces. One geometry promotes a secure positioning of the tubular relative to the first blade while the second geometry promotes a puncturing of the tubular by the second blade.

Abstract: A valve apparatus (100) for a well comprises a valve body (101), and a valve member (102). The valve body (101) includes a first passage (190) that extends through the valve body (101), and at least one second passage (193) that extends through the valve body and laterally from the first passage (190). The valve body (101) being connectable to the well so that a fluid flowing from the well is able to flow through the first passage (190). The valve member (102) being insertable into the first passage (190) and being moveable relative to the valve body (101) so as to thereby control the flow of the fluid from the first passage (190) into each second passage (193).

Abstract: The techniques herein relate to a ram assembly for a blowout preventer for receiving a tubular of a wellbore. The ram assembly includes a ram block for engagement with the tubular, a ram shaft for selectively extending and retracting the ram block, and a ram connector for operatively connecting the ram shaft to the ram block. The ram block has at least one block groove. The ram shaft has a ram head with at least one shaft groove. The ram connector includes at least one shear connector correspondingly disposable in the block groove and the shaft groove whereby the ram shaft is releasably securable to the ram block.

Abstract: A blowout preventer comprises a pair of ram assemblies which are mounted on diametrically opposite sides of a BOP housing. A cylinder-ram is slidably received within each ram assembly and includes a cylindrical cavity. A back plate couples with the outer end of the cylinder-ram and a piston head is positioned in the cavity, forming first and second piston chambers. Hydraulic pressure in the first and second piston chambers forces the cylinder ram from an open position to a closed position, thereby sealing the BOP bore.

Abstract: A ram blowout preventer for sealing a well, the ram blowout preventer including a body having a cavity with a recess; a ram block configured to move inside the cavity; a top seat disposed in the recess and configured to seal the well when in contact with the ram block; a movable lock ring extending inside a groove of the body and a corresponding groove of the top seat and configured to move inside the groove of the body, along a direction substantially parallel to the well; a first seal extending inside a groove of the top seat and configured to contact the body and the top seat; and a second seal extending inside a groove of the ram block and configured to contact the ram block and the top seat. A width of the groove of the body is larger than a width of the lock ring by a predetermined value, which is larger than normal tolerances, and a distance from a centerline of the well to the first seal is larger than a distance from the centerline of the well to the second seal.

Abstract: A valve comprises a valve body defining a throughbore having a throughbore axis, a first ram (100a; 200a) comprising a first seal face (144a,145a; 280a) and a second ram (100b;200b) comprising a second seal face (144b,145b; 280b), wherein the first and second rams are disposed on opposing sides of the throughbore on a ram axis and are actuable to be moved along the ram axis to bring the seal faces together, a channel (142; 242) defined by the first and/or second seal faces configured to accommodate a tubular member (40) in a sealing position when the first and second seal faces are brought together, wherein the first and second seal faces are oriented in a plane which is parallel to the throughbore axis and which is inclined with respect to the ram axis.

Abstract: A shear/seal ram provides a knife edge at the shearing edge and the knife edge is inclined to minimize the cutting force required and to leave a clean cut edge. The knife edge is presented in an opening of the ram, thus the opening is positioned at the axis of the BOP, and consequently the coiled tubing, before the coiled tubing is run through the BOP. A biasing means, such as for example a Bellville spring, forces a sealing sleeve against the underside of the ram to prevent leakage of pressure from below the BOP. Similarly, a plurality of biasing means, referred to herein as “skates”, forces the ram down against the sealing sleeve to seal pressure from above the BOP.

Abstract: A lock assembly of a blowout preventer is provided. The blowout preventer includes a ram assembly slidably positionable in the channel and engageable with a tubular. The ram assembly includes a ram block, a ram cylinder, and a ram shaft. The lock assembly includes a lock cylinder and a lock piston. The lock cylinder is operatively connectable to the ram cylinder. The ram shaft has an end slidably extendable into a lock cavity of the lock cylinder. The lock piston is slidably positionable in the lock cylinder and separates the lock cavity into a lock and a closing chamber. The lock piston has a ram surface engageable with the end when the lock piston is in a locked position, and a ram hole therethrough to receive the end when the lock piston is in an unlocked position whereby the ram block is selectively lockable about the tubular.

Abstract: A locking door assembly, blowout preventer and method are provided. The blowout preventer is for sealing about a tubular extending from a wellbore of a wellsite. The blowout preventer includes a housing having a bore and a channel therethrough. The tubular is positionable through the bore and engageable therein. The blowout preventer also includes a door assembly including a door slidably positionable along an axis of the channel and providing selective access to the channel, and a lock. The lock includes at least one locking member having at least one raised portion extending along the door assembly in a direction transverse to the axis of the channel. The locking member is extendable into at least one corresponding receptacle of the housing and movable therealong between an unlocked and a locked position whereby the door assembly is selectively retractable from the housing.

Abstract: Systems are provided for using position data of a piston connected to a ram block in a blowout preventer to determine a backlash of the ram block, and/or to record a position of the ram block, and/or to calculate an instant when a supplemental closing pressure is desired to be applied, and/or to determine when maintenance of a ram locking mechanism is due, and/or to determine when sealing elements are worn.

Abstract: A pair of shear blades and a blowout preventer having the pair of shear blades. The shear blades are configured to cut a tubular inside the blowout preventer. The shear blades have different geometries of the front cutting surfaces. One geometry promotes a secure positioning of the tubular relative to the first blade while the second geometry promotes a puncturing of the tubular by the second blade.

Abstract: An improved blowout preventer for a well having a casing extending into an underground formation. The blowout preventer has a pair of opposed ram members received within a pair transverse bores within the main housing. The ram members move between an engaged position wherein they engage the pump rod and each other when a pump rod is received through the longitudinal bore in the housing, and a disengaged position where they are retracted from engaging either the pump rod or each other. There are one or more side entry ports within the main housing which permit a fluid or elongate member to be inserted into the casing.

Abstract: A blowout preventer assembly comprising an annular blowout preventer having an annular packing unit and an actuator operable to reduce the internal diameter of the annular packing unit, wherein the assembly further comprises a stripping sleeve having a tubular elastomeric sleeve which in use is positioned generally centrally of the packing unit so that the packing unit surrounds at least a portion of the elastomeric sleeve.

Abstract: A pipe shear ram assembly has a housing having a bore extending vertically therethrough for the passage of a pipe string. Ram blocks have blades positioned such that one slides over the other when the first and second ram blocks are moved toward each other to shear a well pipe. A pair of guide arms extend from one of the rams. The guide arms have tips protruding a greater distance than the blade. Each of the guide arms has an inboard wedge surface beginning at the tip and extending along a line that intersects the longitudinal axis for guiding the pipe string toward a bore axis of the bore in the event the first and second ram blocks are moved to the closed position.

Abstract: Method and blowout preventer for sealing a well. The blowout preventer includes a body having first and second chambers, the first chamber extending substantially perpendicular to and intersecting the second chamber; a ram block configured to move within the first chamber to seal a first region of the second chamber from a second region of the second chamber; a rod connected to the ram block and configured to extend along the first chamber; a piston connected to the rod and configured to move along and within the first chamber; a bonnet configured to receive the piston, the bonnet being detachably attached to the body; and an indicator device partially mounted outside the bonnet and configured to indicate a physical position of the ram block within the body.

Abstract: Apparatuses for providing a visual indication outside a blowout preventer (BOP) relative to a position of ram blocks inside the BOP, and methods of adding such apparatuses to existing blowout preventers are provided. An apparatus has an indicator rod, a detectable portion and a sealing assembly. The indicator rod has an end extending outside an end cap of the BOP, and is configured to engage with a tail rod of a ram block of the BOP, and to switch between a first position when the BOP is in a close state, and a second position when the BOP is in an open state. The detectable portion is located outside the end cap and is configured to provide a visual indication relative to a current position of the indicator rod. The sealing assembly is configured to seal a space inside the end cap from an environment in which the BOP operates.

Abstract: The method of providing a desired motive force for one or more rams of a subsea blowout preventer as a function of a desired pressure differential across one or more pistons on the subsea blowout preventer when the desired pressure differential is higher than the gauge pressure of the accumulators supplying the pressure, comprising providing one or more pistons connected to the one or more rams, the pistons having a distal side and a proximate side with respect to the rams, providing a first pressure from the accumulators to the distal side of the pistons, providing a tank to contain a second pressure less than the ambient pressure of seawater at the location of the subsea blowout preventer, providing a pressure reducing valve which exhausts into the tank and reduces the pressure on the proximate side of the one or more pistons to proximately the difference between the desired pressure differential and the first pressure further comprising that the pressure differential across the one or more pistons is proxi

Abstract: Methods for deploying a subsea blowout preventer stack system comprising a lower marine riser package, a blowout preventer stack with a first ram blowout preventer, and an additional blowout preventer package releasably coupled to the blowout preventer stack and comprising a second ram blowout preventer. The subsea blowout preventer stack assembly can be deployed by coupling a drilling riser to the lower marine riser package that is releasably connected to the blowout preventer stack. The lower marine riser package and blowout preventer stack are then toward a subsea wellhead and then landed on the additional blowout preventer package that is coupled to the subsea wellhead.