Abstract: An apparatus for use in a drill string is disclosed. The apparatus includes an inner core assembly having a first and second transverse bore, and wherein the inner core assembly has a first end and a second end. The apparatus further includes a first and second piston, disposed within the first and said second transverse bore, for closing an internal longitudinal bore of the inner core assembly, and wherein the first end of the inner core assembly is connected to the drill string and the second end is operatively connected to a swivel or top drive. The pistons are movable into the internal longitudinal bore of the inner core assembly in order to close the internal longitudinal bore. The apparatus may further comprise a third and fourth transverse bore positioned within the inner core assembly and third and fourth pistons, disposed within the third and fourth transverse bores of the inner core assembly, for closing the internal longitudinal bore of the inner core assembly.

Abstract: A process to transport a blow out preventer for a drilling rig having a drawworks wherein the blow out preventer is transported between a storage area and a use position over a wellbore. The process includes the steps of connecting an upper connector end of an elongated running tool to the drawworks of the drilling rig. The elongated running tool is moved in position parallel to the wellbore using the drawworks of the drilling rig. The running tool is lowered so that a stab connection is made between a lower connector end of the running tool and the blow out preventer. The blow out preventer is thereafter moved over and in alignment with the wellbore.

Abstract: A blowout preventer transportation and installation system. The system includes a transportation skid assembly having a transport carriage to raise the blowout preventer between a horizontal transport position and a vertical position. The transport carriage on the skid assembly moves the blowout preventer with respect to the skid assembly. A boomer assembly having a crane mounted on a carriage frame on a boomer assembly frame raises and lowers the blowout preventer. The carriage frame moves with respect to the boomer assembly frame to move the blowout preventer over a wellhead. A control line support assembly supports hose lines extending between the blowout preventer and a hydraulic power unit.

Abstract: A blowout preventer assembly 10 includes opposed rams 12, 14, each including a rubber or elastomer sealing assembly 16, 18, with a plurality of inserts 20 forming an array 22 of metal inserts within each sealing assembly. Each insert has an upper body 24, a lower body 26, and a rib 50. Each upper and lower body includes a trailing face 36, a radially outward opposite face 38 and a leading face 40. An antiextrusion ledge 46 minimizes the extrusion gap between the OD of a tubular in the BOP and the leading face of the metal inserts in the array.

Abstract: A bonnet lock mechanism for a blowout preventer including an angled surface disposed in the blowout preventer, a latching dog having a tapered surface disposed in the bonnet, and a lock actuator operatively coupled to the latching dog. The the lock actuator is adapted to move the latching dog such that the latching dog is in locking engagement with the angled surface of the blowout preventer.

Abstract: A blowout preventer for coiled tubing includes a pressure regulator for a slip ram so that the coiled tubing can be held firmly without exceeding the yield strength of the coiled tubing material and without damaging the coiled tubing.

Abstract: Apparatus and method are provided for lifting heavy loads beneath the floor of a drilling rig or a platform. A base skid supports tables to which winch bases are attached. Winches, usually four in number, are placed on the winch bases and the cables of the winches are placed through sheaves and attached to a double line bar. Sheaves are attached to a load, such as a blowout preventer. Cradle lines may support a blowout preventer. Load cells may be used with the winch cables.

Abstract: A reciprocating lubricator includes a lubricator base, a lubricator tube connected at the top to a lubricator head and inserted through a packing in the lubricator base to provide a sealable chamber adapted to accommodate a downhole tool to be inserted into a wellbore against well fluid pressure. The chamber in the lubricator tube is sealed using equipment mounted to the lubricator head. Injectors interconnecting the lubricator base and the lubricator head reciprocate the lubricator tube through the lubricator base. When a downhole tool is inserted into the wellbore, the lubricator head rests against the lubricator base to provide a low, safe and stable position for operation of the equipment mounted to the top of the lubricator head.

Abstract: A method of providing a liner which can be rolled up on a reel for convenient transport and which can be unrolled into the bore of an oil or gas well and expanded to the approximate bore size of the casing size which the liner was run through and is collapsed in a way which allows sealing and stripping with a blowout preventer for well control protection during running and providing smooth surface support wedging without the need for marking the pipe with slip teeth.

Abstract: Methods and apparatus for handling blowout preventer stacks. In one embodiment the handling system includes a cart, or skid, providing a base platform, a tilting frame, and a lifting frame. The stack is attached to the lifting frame, which is slidingly supported by the tilting frame, which pivots relative to the cart. The cart provides for positional adjustment of the stack in a first horizontal direction, while positional adjustment in a second, perpendicular horizontal direction is provided by a lateral adjustment mechanism coupling the tilting frame and the cart. The lifting frame can be moved vertically relative to the cart and also provides for rotational adjustment of the stack about its central axis.

Abstract: A blowout preventer (BOP) protector is adapted to support a tubing string in a wellbore so that the tubing string is directly accessible during a well treatment to stimulate production. The BOP protector includes a mandrel having a sealing assembly mounted to its bottom end for pack-off in a casing of a well to be stimulated. The mandrel is connected at its top end to a fracturing head, including a central passage and radial passages in fluid communication with the central passage. The mandrel is locked in a fixed position by a lockdown nut that prevents upward movement induced by fluid pressures in the wellbore. The advantages are that the BOP protector permits access to the tubing string during well treatment and enables an operator to move the tubing string up and down or run coil tubing into or out of the wellbore without removing the tool. This reduces operation costs, saves time and enables many new procedures that were previously impossible or impractical.

Abstract: An apparatus for protecting equipment in a wellhead from exposure to fluid pressures, abrasives and corrosive fluids used in a well treatment to stimulate production, includes a mandrel to be inserted through the wellhead into an operative position. The apparatus further includes injectors for reciprocating the mandrel to and from the operative position. The injectors are connected on their top ends to a connector plate that provides a support platform to permit equipment, such as blowout preventers, wireline units, coil tubing injectors or the like, to be mounted to the top of the apparatus.

Abstract: A method for eliminating the presence of micro-annuluses associated with a subsea hydrocarbon producing wellbore for accurate gathering of data within the subsea hydrocarbon producing wellbore. The method involves using a sea floor pressure head assembly in conjunction with a subsea blow out preventer, where the sea floor pressure head assembly has an elongated tube with a stop ring formed thereon and an ambient pressure side. The blow out preventer is connected to the entrance of the subsea hydrocarbon producing wellbore, and includes an inflatable bladder and is connected to a hollow riser connected thereto.

Abstract: A tubing assembly including a tubing string and tubing hanger provides a fluid passage with backpressure threads for securing a backpressure plug in a fluid-tight seal below the tubing hanger, so that the tubing hanger can be removed from the tubing string. The back pressure threads are preferably incorporated in a backpressure adapter pin connected between the tubing string and the tubing hanger. The adapter pin may also incorporate external weight-bearing shoulders for snubbing and/or suspending the tubing assembly. The backpressure plug is inserted or removed using a backpressure plug tool that slides through a packing in a pressurized casement that maintains pressure in an axial passage through a control stack of the wellhead.

Abstract: An articulated slip for a slip ram includes a plurality of articulated linked segments, attached to vertical pins or axles which are parallel to the axis of a coiled tubing, for rotatable movement of the linked segments. The articulated linked segments are concave for abutting contact with a tubular through the slip ram. The pins are mounted to a slip ram, which comprises a piston within a cylinder, in the conventional manner for a blowout preventer (BOP) ram. When the slip ram is actuated, the ram moves forward, wrapping the articulated elements around coiled tubing in a gripping motion, much like the fingers of a human hand.

Abstract: A flow completion apparatus comprises a wellhead housing installed at an upper end of a well bore and a tubing spool connected over the wellhead housing. The tubing spool includes a central bore extending axially therethrough, a production outlet communicating with the central bore and an annulus passageway communicating with the tubing annulus. A tubing hanger is supported in the central bore and includes a production bore extending axially therethrough and a production passageway communicating between the production bore and the production outlet. The tubing spool comprises a workover passageway extending between the annulus passageway and a portion of the central bore located below the top of the tubing hanger. Furthermore, the tubing hanger comprises an annulus bore extending between the workover passageway and the top of the tubing hanger.

Abstract: A device for use in removing and installing an inline component from a drill string that is depending downward over a deck. The device has an elongate member with a flange adapted to abut the deck and support the elongate member in a substantially upright orientation, and an engagement member on the elongate member adapted to rotably engage the inline component.

Abstract: A bidirectional sealing blowout preventer including bidirectional sealing blowout preventer rams, and fluid communication systems for equalizing pressure between the backs of ram guideways in a bidirectional sealing blowout preventer and a passageway through the blowout preventer. Methods for operating a bidirectional sealing blowout preventer to seal a well around a well pipe against downhole pressure to control the well, and to seal a well around a well pipe to pressure test another blowout preventer or other apparatus in a stack.

Abstract: An apparatus for rigless subterranean well completion, re-completion, servicing or workover includes at least two substantially vertically oriented double acting prime movers incorporated into a spool for pressure containment, which is mounted to the top of a wellhead. The spool further includes a Bowen union mounted to a top thereof for sealingly connecting an annular adapter, which provides a seal between the well bore and a tubular that is inserted under the well fluid pressure into the well by the prime movers. The spool may further include a mechanism for securing a hydraulic crane that can be temporarily mounted to the top of the spool to hoist equipment and tools above the wellhead when the prime movers are used to support heavy workloads induced by well fluid pressure or the weight of a tubing string. The apparatus can be used in various operations for well completion, re-completion, servicing or workover without the necessity of using a servicing rig.

Abstract: Apparatus and method are provided for lifting heavy loads beneath the floor of a drilling rig or a platform. A base skid supports tables to which winch bases are attached. Winches, usually four in number, are placed on the winch bases and the cables of the winches are placed through sheaves and attached to a double line bar. Sheaves are attached to a load, such as a blowout preventer. Cradle lines may support a blowout preventer. Load cells may be used with the winch cables.

Abstract: A slip spool for selectively supporting or snubbing a tubing string suspended in a wellbore can be mounted to a wellhead. The slip spool has an axial passage to be aligned with the wellbore and at least two radial passages extending through a side wall of the slip spool and communicating with the axial passage. At least two slip blocks are slidably supported within the respective radial passages. The slip spool further includes actuators for moving the respective slip blocks between an extended position in which they engage a component in the tubing string that provides a weight-bearing shoulder, and a retracted position in which the slip blocks clear the axial passage of the slip spool. The slip spool facilitates live well service operations and eliminates scoring of an exterior surface of the tubing.

Abstract: One embodiment of the present invention discloses a well pressure activated pack off head to be used in conjunction with a wellhead situated on a hydrocarbon producing wellbore. The well pressure activated pack off head comprises a hollow body formed for coaxial connection to the wellhead, the hollow body must also provide for unobstructed passage of a data transmitting wireline therethrough.

Abstract: A subterranean oil or gas well apparatus is provided. The apparatus includes a single-bore production tubing hanger arranged concentric with a wellhead. The tubing hanger includes a plurality of ports and channels arranged about the tubing hanger to give operators access to the production tubing annulus and provide chemical injection capability. The ports are closable by a sliding valve. The apparatus also includes annulus and production radial-bore stab assemblies between a christmas tree and an internal crossover assembly. The stab assemblies are extendable and retractable between the chirstmas tree and the crossover assembly to allow the retrieval and installation of each independently.

Abstract: An apparatus for use in a drill string is disclosed. The apparatus includes an inner core assembly having a first and second transverse bore, and wherein the inner core assembly has a first end and a second end. The apparatus further includes a first and second piston, disposed within the first and said second transverse bore, for closing an internal longitudinal bore of the inner core assembly, and wherein the first end of the inner core assembly is connected to the drill string and the second end is operatively connected to a swivel or top drive. The pistons are movable into the internal longitudinal bore of the inner core assembly in order to close the internal longitudinal bore. The apparatus may further comprise a third and fourth transverse bore positioned within the inner core assembly and third and fourth pistons, disposed within the third and fourth transverse bores of the inner core assembly, for closing the internal longitudinal bore of the inner core assembly.

Abstract: A wellhead isolation tool comprises a threaded drive rod coaxially aligned with a tubular mandrel having a smooth outer surface. A motor displaces the threaded drive rod vertically without rotating the drive rod to move the tubular mandrel through a wellhead into a tubular element in a well. The lower end of the tubular mandrel will sealingly engage the tubular element in the well so that treating fluids or other substances such as, but not limited to, chemicals and erosive flows, can be displaced therethrough at high pressures into the well to fracture or otherwise treat the well without damaging the wellhead.

Abstract: A modular work system permits Rig Up time to be substantially reduced by reducing the number of crane lifts required to offload equipment for a transport boat or vehicle. This is achieved by developing transport skids capable of holding multiple system components. The number of equipment components that must be mechanically coupled on location is reduced by pre-assembling the components and maintaining the assembly in operating condition during storage and transport. Skid design concepts are employed, wherein a skid system carries various pre-assembled components for transport, storage and operation. Specifically, a skid sub-system includes various related components. The components are either pre-assembled or are designed to complete a sub-assembly through final assembly on the rig. The skid is moved into place using the crane, and the assembly is completed. Additional sub-systems are mounted on additional skids which are designed to be mated with the other related skids and sub-assemblies.

Abstract: A wellhead isolation tool and a wellhead assembly incorporating such a tool are provided. The wellhead assembly has an annular assembly coupled to a well. The annular assembly may include a casing head coupled to the well and a tubing head mounted over the casing head. The wellhead isolation tool is suspended in the annular assembly. The wellhead isolation tool has a first end portion extending above the annular assembly and a second end portion below the first end portion within the annular assembly. A production casing suspended in the annular assembly and is aligned with the wellhead isolation tool.

Abstract: A high torque and high capacity rotatable center core and floatable sealed body apparatus with universal ram applications. The apparatus includes a central core assembly, connected between a swivel on its upper end and the work string below, with the central core assembly having a central passageway therethrough. The apparatus further includes a first outer assembly, having a central bore for slidably engagement around a portion of the central core assembly. In one embodiment, a second outer assembly is included, with the second outer assembly having a central bore for slidably engaging around a portion of the central core assembly above the first outer assembly. A pair of opposing transverse bores is contained within both of the first and second outer assemblies, corresponding to a pair of transverse bores in the central core assembly.

Abstract: A high torque and high capacity rotatable center core and floatable sealed body assembly with universal ram applications and method for use in a drill string, including a central core assembly, connected between a swivel on its upper end and the drill string below, having a central passageway therethrough; a first outer assembly, having a central bore for slidably engagement around a portion of the central core assembly; a second outer assembly, having a central bore for slidably engaging around a portion of the central core assembly above the first outer assembly; a pair of opposing transverse bores in both the first and second outer assemblies, corresponding to transverse bores in the central core assembly; sleeve members for aligning the bores of the core assembly and the first and second outer assemblies; and rams positionable in the transverse bores in the first and second outer assemblies for sealing off the passageway in the central core assembly when moved to the sealing position.

Abstract: A blowout preventer (BOP) protector is adapted to support a tubing string in a wellbore so that the tubing string is directly accessible during a well treatment to stimulate production. The BOP protector includes a mandrel having a sealing assembly mounted to its bottom end for pack-off in a casing of a well to be stimulated. The mandrel is connected at its top end to a fracturing head, including a central passage and radial passages in fluid communication with the central passage. The mandrel is locked in a fixed position by a lockdown nut that prevents upward movement induced by fluid. pressures in the wellbore. The advantages are that the BOP protector permits access to the tubing string during well treatment and enables an operator to move the tubing string up and down or run coil tubing into or out of the wellbore without removing the tool. This reduces operation costs, saves time and enables many new procedures that were previously impossible or impractical.

Abstract: Apparatus for inserting a tubing hanger into a tubing head spool on a live well includes a landing spool and a landing joint that reciprocates through a top end of the landing spool. The landing joint is connected to the tubing hanger. The landing spool is connected to a top flange of a blowout preventer on the live well. The blowout preventer is then opened and the tubing hanger is injected into the tubing head spool. A lifting spool is also provided to permit the tubing hanger to be injected without the use of a service rig. Safety is improved, costs reduced and production is facilitated because the well does not have to be killed.

Abstract: A disconnect system for coiled tubing. A first end of the coiled tubing is disconnected from a second end of the coiled tubing by holding the coiled tubing in a stationary position at a first and a second location. The coiled tubing is then sheared at one or more locations between the first and the second location.

Abstract: A subterranean oil or gas well apparatus is provided. The apparatus includes a single-bore production tubing hanger arranged concentric with a wellhead. The tubing hanger includes a plurality of ports and channels arranged about the tubing hanger to give operators access to the production tubing annulus and provide chemical injection capability. The ports are closable by a sliding valve. The apparatus also includes annulus and production radial-bore stab assemblies between a christmas tree and an internal crossover assembly. The stab assemblies are extendable and retractable between the chirstmas tree and the crossover assembly to allow the retrieval and installation of each independently.

Abstract: The invention is directed to a tensioner/slip-joint module for providing a conduit from a floating vessel at the surface of the ocean to the blowout preventer stack, or production tree, which is connected to the wellhead at the sea floor. The tensioner/slip-joint module compensates for vessel motion induced by wave action and heave and maintains a variable tension to the riser string alleviating the potential for compression and thus buckling or failure of the riser string. The tensioner/slip-joint module of the present invention preferably includes at least one mandrel having at least one hang-off donut; at least one upper flexjoint swivel assembly, at least one radially ported manifold, at least one tensioning cylinder, and at least one slip-joint assembly combined in a single unit.

Abstract: A high torque and high capacity rotatable center core and floatable sealed body apparatus with universal ram applications. The apparatus includes a central core assembly, connected between a swivel on its upper end and the work string below, with the central core assembly having a central passageway therethrough. The apparatus further includes a first outer assembly, having a central bore for slidably engagement around a portion of the central core assembly. In one embodiment, a second outer assembly is included, with the second outer assembly having a central bore for slidably engaging around a portion of the central core assembly above the first outer assembly. A pair of opposing transverse bores is contained within both of the first and second outer assemblies, corresponding to a pair of transverse bores in the central core assembly.

Abstract: A mount for a bonnet of a blowout preventer includes at least one support member coupled to a body of the blowout preventer, and a bonnet mounting member moveably coupled to the at least one support member and adapted to move substantially normal to a face of the body of the blowout blowout preventer, wherein the bonnet is coupled to the bonnet mounting member.

Abstract: A bonnet lock mechanism for a blowout preventer that includes a radial lock. A radial lock displacement device is coupled to at least one lock actuator. The radial lock displacement device is adapted to radially displace the radial lock to lock a bonnet to a body of the blowout preventer. A bonnet lock mechanism for a blowout preventer that includes a radial lock positioned in a body of the blowout preventer. At least one lock actuator is coupled to the radial lock and is adapted to radially displace the radial lock to lock a bonnet to the body of the blowout preventer.

Abstract: Disclosed are a bidirectional sealing blowout preventer, bidirectional sealing blowout preventer rams, and fluid communication systems for equalizing pressure between the backs of ram guideways in a bidirectional sealing blowout preventer and a passageway through the blowout preventer. Disclosed are methods for operating a bidirectional sealing blowout preventer to seal a well around a well pipe against downhole pressure to control the well, and to seal a well around a well pipe to pressure test another blowout preventer or other apparatus in a stack.

Abstract: In one aspect a rotating hanger comprises a dognut sleeve having a bore and an outer profile compatible for support in the casing bowl and sealing thereto and a tubular hanger mandrel fitted rotatably to the dognut sleeve's bore and having an upper shoulder projecting above the dognut sleeve for interaction with casing bowl holddown screws which, when engaged, restrain rotation and prevent ejection from the casing bowl. In another aspect, an improved well tubing rotator and hanger system is provided the rotatable tubing hanger, a tubular connector sub threaded to the hanger mandrel and a rotator splined to the connector sub, the splined connector sub enabling rotational coupling without imposing hanger loads into the rotator which enables use of smaller, low profile and economical rotators. In another aspect, a rotator having a threaded nozzle wellhead connection is convertible to a flanged rotator.

Abstract: A rotatable mount for a blowout preventer bonnet. A slide mounting bar is slidably couples to a body of the blowout preventer. The slide mounting bar is adapted to move along an axis of a side opening of the body of the blowout preventer. A swivel is coupled to the mounting bar and to the bonnet. The swivel is adapted to enable rotation of the bonnet when the bonnet is disengaged from the body of the blowout preventer.

Abstract: A method and apparatus is provided to prevent axial twisting, vibration, and bounce of individual components comprising a stack of operational surface components for a well which may occur during the transportation, hoisting, or use of the stack. A transport and support frame is provided which comprises a plurality of substantially vertical members, a plurality of substantially horizontal members interconnecting the vertical members, and a support structure to secure the stack within the frame.

Abstract: An apparatus for handling safety valves used for shutting off high pressure upward flow through drill pipe or tubing. The apparatus includes an adjustable clamp assembly for holding the safety valve; a three-stage double-acting hydraulic extension system to provide horizontal (and optionally, rotational) movement of the safety valve; a telescoping, mechanically-extending stanchion with a stabilizing plate attached to the hydraulic extension system; a stable track assembly for vertical movement of the apparatus; and a positioning arm with a yoke for placement against the drill pipe or tubing, providing a distance measurement used to vertically align the safety valve with the drill pipe or tubing.

Abstract: A rotatable mount for a blowout preventer bonnet. A slide mounting bar is slidably couples to a body of the blowout preventer. The slide mounting bar is adapted to move along an axis of a side opening of the body of the blowout preventer. A swivel is coupled to the mounting bar and to the bonnet. The swivel is adapted to enable rotation of the bonnet when the bonnet is disengaged from the body of the blowout preventer.

Abstract: A gate valve has downstream shear and seal capabilities in which the gate will stroke far enough to cover the downstream seat interface, and has a single shearing surface for shearing of a wireline. The gate has an inlay of a hard ductile material such as Stellite® along the shearing edge of the gate. The gate also has a coating of an extremely hard material such as tungsten carbide on the sealing surface of the gate. The seat also has an inlay of a hard ductile material such as Stellite® along its shearing edge. The gate fully covers and seals the upstream seat interface after the shear media has fallen below the upstream gate/seat interface. An upstream lip seal for the upstream seat ring is energized to seal on upstream pressure.

Abstract: A method is provided for eliminating the presence of micro-annuluses associated with a subsea hydrocarbon producing wellbore for accurate gathering of data within the subsea hydrocarbon producing wellbore. The method involves using a sea floor pressure head assembly in conjunction with a subsea blow out preventer, where the sea floor pressure head assembly has an elongated tube with a stop ring formed thereon and an ambient pressure side. The blow out preventer is connected to the entrance of the subsea hydrocarbon producing wellbore, and includes an inflatable bladder and is connected to a hollow riser connected thereto.

Abstract: A blowout preventer (BOP) protector is adapted to support a tubing string in a well bore so that the tubing string is directly accessible during a well treatment to stimulate production. The BOP protector includes a mandrel having an annular sealing body bonded to its bottom end for sealing engagement with a bit guide that protects a top of a casing of a well to be stimulated. The mandrel is connected at its top end to a fracturing head, including a central passage and radial passages in fluid communication with the central passage. The mandrel is locked in a fixed position by a lockdown mechanism that prevents upward movement induced by fluid pressures in the wellbore and downward movement induced by the weight of a tubing string supported at a top of the fracturing head by a tubing adapter.

Abstract: A flow completion apparatus for controlling the flow of fluid through a tubing string which extends into a well bore and defines a tubing annulus surrounding the tubing string, the flow completion apparatus comprising a wellhead housing which is installed at an upper end of the well bore; a tubing spool which is connected over the wellhead housing and which includes a central bore that extends axially therethrough, a production outlet which communicates with the central bore, and an annulus passageway which communicates with the tubing annulus; a tubing hanger which is supported in the central bore, is connected to an upper end of the tubing string, and includes a production bore which extends axially therethrough and a production passageway which communicates between the production bore and the production outlet; a first closure member which is positioned in the production bore above the production passageway; and a first annular seal which is positioned between the tubing hanger and the central bore above t

Abstract: A system for use in a subsea well includes a sealing element having an inner surface defining a bore through which a carrier line of a tool string may extend. A pressure-activated operator is coupled to the sealing element and is adapted to cause the sealing element to deform generally radially inwardly to allow the inner surface to apply a force to seal around the carrier line. A fluid pressure conduit extends from a sea surface pressure source to the pressure-activated operator. The sealing element is part of a pack-off device that can be used in a subsea blow-out preventer.

Abstract: A blowout preventer (BOP) protector featuring a low profile and a mechanical lockdown mechanism is described. The BOP protector includes a mandrel having an annular sealing body bonded to its bottom end for sealing engagement with a bit guide which protects a top of a casing of a well to be stimulated with acidifying or fracturing fluids. The mandrel is locked down with a mechanical lockdown mechanism having a broad range of adjustment. The advantages include a low profile, the security of a mechanical lockdown mechanism, and full access to the casing with downhole tools.

Abstract: The rotatable blowout preventer 10 comprises a stationary outer housing 12 and a rotatable inner housing 38 having a curved surface 42 thereon defining a portion of a sphere. An annular packer assembly 46 includes spherical packer elements for sliding engagement with the curved surface of the inner housing such that a packer assembly may seal against various sized tubulars. A lower rotary seal 98 between a piston 56 and the outer housing 12 is exposed to the differential between pressurized hydraulic fluid and the well pressure within a lower end of the bore 32 within the outer housing. A flow restriction member 114 between the rotatable inner housing and the outer housing reduces fluid pressure downstream from the flow restriction to less than 40% of the upstream pressure. The upper rotary seal 120 is open to atmospheric pressure and is subjected to this reduced pressure.