Abstract: An apparatus and method for containing oil from a deep water (greater than 1,000 meters) oil well is disclosed herein. The apparatus has an anchor section, a plurality of riser sections, an upper section and a flow tube. A pressure within the apparatus is equal to a pressure outside of the apparatus to prevent collapse of the apparatus, and to prevent crystallization. Oil is suctioned from the interior of the apparatus through the flow tube to a surface of the ocean.

Abstract: An apparatus and method for containing oil from a deep water (greater than 1,000 meters) oil well is disclosed herein. The apparatus has an anchor section, a plurality of riser sections, an upper section and a flow tube. A pressure within the apparatus is equal to a pressure outside of the apparatus to prevent collapse of the apparatus, and to prevent crystallization. Oil is suctioned from the interior of the apparatus through the flow tube to a surface of the ocean.

Abstract: The present invention relates to protector apparatus (30) for protecting at least one cable (24) during operation of a diverter (28). The protector apparatus (30) comprises at least one protector assembly substantially formed of a plastics material. The protector assembly defines a plurality of bores, a first of the plurality of bores being configured to receive a string (23) and a second of the plurality of bores being configured to receive a cable (24). The protector assembly is further configured to define an external surface with which an operating diverter engages when the protector apparatus is in use and a string is received in the first bore.

Abstract: A technique enables protection of subsea wells. The technique employs a subsea test tree and associated control system to ensure control over the well in a variety of situations. The subsea test tree may be formed with an upper portion releasably coupled to a lower portion. The upper portion employs at least one upper shut-off valve, and the lower portion employs at least one lower shut-off valve to protect against unwanted release of fluids from either above or below the subsea test tree. The subsea test tree also is coupled with the control system in a manner which allows control to be exercised over the at least one upper shut-often valve and the at least one lower shut-off valve.

Abstract: The invention relates to a safety joint (10; 100; 200) for a riser consisting of two telescoping parts that are arranged to break in the event of a predetermined axial tension load. The joint also comprises means (21, 41; 121, 141; 221, 241) for closing the passage in the joint in the event of fracture where the means are activated by means of the forces generated during the separation.

Abstract: Pressure-balanced accumulator apparatus for use in subsea operations is disclosed which comprises a housing and an accumulator within the housing at the first end of the housing. The accumulator has first and second chambers that are hermetically sealed from one another, with a pressurized gas in the first chamber and a pressurized fluid in the second chamber. A third chamber in the housing abuts the accumulator and contains silicon oil fluid. A movable piston is located within the housing proximate the second end of the housing. Ambient pressure is communicated to one end of the piston, and ambient pressure plus the pressure in the second chamber is communicated to the second end of the piston. The cross-sectional areas of the two ends of the piston are selected to optimize the pressure at which the piston begins to expel fluid from the second chamber.

Abstract: A tensioning apparatus for applying a substantially constant tension to a workover riser (12) includes a first portion (40) adapted to be coupled to a workover riser, a second portion (44) adapted to be coupled to a marine riser (14) and tensioning means (46) for providing relative movement between the first portion and the second portion to, in use, tension the workover riser.

Abstract: Pressure-balanced accumulator apparatus for use in subsea operations is disclosed which comprises a housing and an accumulator within the housing at the first end of the housing. The accumulator has first and second chambers that are hermetically sealed from one another, with a pressurized gas in the first chamber and a pressurized fluid in the second chamber. A third chamber in the housing abuts the accumulator and contains silicon oil fluid. A movable piston is located within the housing proximate the second end of the housing. Ambient pressure is communicated to one end of the piston, and ambient pressure plus the pressure in the second chamber is communicated to the second end of the piston. The cross-sectional areas of the two ends of the piston are selected to optimize the pressure at which the piston begins to expel fluid from the second chamber.

Abstract: A system for the storage of crude oil, natural gas and/or refined petroleum products at an offshore location includes a group of tanker vessels or concrete structures on the ocean floor attached to a manifold. The manifold is connected to sources of crude oil, natural gas and/or refined petroleum products. Each vessel includes a security system and a moving arrangement which allows the vessel to weathervane in response to wind and wave forces.

Abstract: A method for preparing to move a floating structure away from a wellbore drilled below the bottom of a body of water includes filling a riser extending from the bottom of the body of water to the floating structure with water. The water in the riser is displaced to a selected first depth below the water surface. The riser is sealed at a second selected depth shallower than the first selected depth. The portion of the riser above the second selected depth is withdrawn onto the floating structure.

Abstract: A tensioning device (15) for a riser (5) connecting a subsea borehole (7) with a floating installation (1) on the surface of the sea (11), where the tensioning device (15) is provided with telescoping tubes (27, 27?) and also several evenly spaced hydraulic cylinders (31, 31?) arranged in a peripherally encircling manner and mainly in the longitudinal direction of the riser, and where the tension in the riser is exerted through hydraulic pressure in said cylinder (31, 31?), the tensioning device (15) consisting of two successive, interconnected telescopic tensioning units (23, 25), the tensioning units (23, 25) being designed separately to maintain a prescribed tension in the riser (5).

Abstract: The present invention relates generally to offshore drilling and production operations, and, more particularly, to marine drilling workover/intervention tensioning and compensating devices and methodologies. A heave compensated hydraulic workover device and/or system is provided comprising a hydraulic tensioning cylinder system disposed beneath a rig floor and adapted to be connected at a mandrel to the rig floor through a rotary table disposed in the rig floor. The heave compensated hydraulic workover device and/or system also comprises a well intervention apparatus disposed at least partially within the hydraulic tensioning cylinder system beneath the rig floor, the well intervention apparatus capable of being used in conjunction with at least one of a well, a wellhead, a blow-out pressure system, a jointed tubular, a pipe, and a drilling string.

Abstract: An arrangement and a method to control and regulate the bottom hole pressure in a well during subsea drilling at deep waters: The method involves adjustment of a liquid/gas interface level in a drilling riser up or down. The arrangement comprises a high pressure drilling riser and a surface BOP at the upper end of the drilling riser. The surface BOP havs a gas bleeding outlet. The riser also comprises a BOP, with a by-pass line. The drilling riser has an outlet at a depth below the water surface, and the outlet is connected to a pumping system with a flow return conduit running back to a drilling vessel/platform.

Abstract: A system and method for controllably separating a conduit into an upper portion and a lower portion. The system includes a first valve in the upper portion of the conduit above a point of separation, and a second valve in the lower portion of the conduit below the point of separation. When the conduit is separated, the valves are actuated to cease flow therethrough and prevent loss of fluids into the seawater. A hang-off tool in the lower portion of the conduit engages the well and supports the lower portion of the conduit.

Abstract: A lockdown device for securing a tubing hanger to a production member comprises a lockdown member which is mounted on the production member and is movable into and out of engagement with a corresponding locking profile on the tubing hanger, and an actuating mechanism for moving the lockdown member into and out of engagement with the locking profile.

Abstract: The disclosure concerns a method and apparatus for repairing or structurally reinforcing an oil and gas well tubular member, or an assembly of tubular members. The assembly to be repaired can include a smaller diameter inner flow conveying conduit (or production tubing) and a larger diameter concentrically placed surface casing, providing an annulus in between the production tubing and the surface casing. A third casing pipe of largest diameter, the drive pipe is placed around the surface casing string. Other “conductor” casing pipes can be positioned around the surface casing inside the drive pipe. Part of the surface casing string (or other conductor pipe) can suffer damage due to corrosion. A sleeve or repair member is placed around the casing string or other tubular member at a damaged portion.

Abstract: An arrangement and a method to control and regulate the bottom hole pressure in a well during subsea drilling at deep waters: The method involves adjustment of a liquid/gas interface level in a drilling riser up or down. The arrangement comprises a high pressure drilling riser and a surface BOP at the upper end of the drilling riser. The surface BOP havs a gas bleeding outlet. The riser also comprises a BOP, with a by-pass line. The drilling riser hasan outlet at a depth below the water surface, and the outlet is connected to a pumping system with a flow return conduit running back to a drilling vessel/platform.

Abstract: Subterranean reservoir monitoring method, computer system with programming code for implementing the method, and computer readable media and data signal embodying such programming code, the method including one or more of: (a) reservoir screening; (b) reservoir modeling; (c) generating model seismic data from a model; (d) model modification based on current VSP data; (e) repeating step (c) and step (d) until differences between the model and VSP data are as desired; (f) obtaining model production data from a reservoir model, and if necessary modifying the model and returning to step (c); (g) generating seismic model data for time t; and (h) comparing seismic model data with actual seismic data for time t, and if necessary modify the reservoir model and return to step (f) or modify the model of the subteranean and return to step (c).

Abstract: A method for carrying out operations on petroleum and gas fields is provided. The method involves using a platform which is located underwater when in working position at a depth where it is not subject to storm waves or under the lower surface of an ice field. The platform is made in the form of a structure which is water-tight and which includes an inner volume in which all the equipment, systems and structures are provided. The platform is directed from the surface using a surface complex which moves on the water or the ice field at the same speed as that of the current or the ice drift in the opposite direction.

Abstract: A triggering mechanism for a triggering valve (1) of a hydraulic emergency unlock circuit for unlocking hydraulically operated gripping members of a riser connector which connects a lower end of a riser (2) to a wellhead on a sea floor. The triggering mechanism comprises a cam ring (5) secured to a displaceable part (4) of a flex joint for the riser (2), and an actuator ring (8) which by means of hydraulic cylinders are translatory movable towards a stationary part (3) of the flex joint. An angular displacement (&agr;) of the riser (2) causes an angular displacement (&agr;) of the cam ring (5), which contacts the actuator ring (8) and forces the actuator ring (8) towards the stationary part (3) of the flex joint, causing an activating of a trigger (13) for the triggering valve (1).

Abstract: A breakaway joint for releasably connecting a first component to a second component, comprises a first member to which the first component is attached; a second member to which the second component is attached; a plurality of columnar members each having first and second ends, the first ends being coupled to the first member; and a mechanism engaged by both the second member and the second ends of the columnar members for latching the first member to the second member and for converting a tensile load acting between the first and second members into a compressive load acting on the columnar members; wherein when the tensile load reaches a predetermined level, the columnar members will buckle and the latching means will release the first member from the second member.

Abstract: The present invention discloses apparatus and methods for replacing a BOP with a gate valve to thereby save space, initial costs, and maintenance costs that is especially beneficial for use in offshore subsea riser packages. The method provides a gate valve capable of reliably cutting tubing utilizing a cutting edge with an inclined surface that wedges the cut portion of the tubing out of the gave valve body. A method and apparatus is provided for determining the actuator force needed to cut the particular size tubing.

Abstract: There is provided a guide for a buoyancy can on a floating offshore platform. The platform includes at least one support structure adjacent the buoyancy can. The guide comprises at least one compression pad supported by the support structure and adjacent the exterior surface of the buoyancy can. Lateral movement of the buoyancy can toward the support structure compresses the compression pad so as to absorb the force generated by the buoyancy can movement, and so as to protect the buoyancy can and components of the floating offshore platform from damage.

Abstract: A surface blow-out prevention support system comprising a support accommodating the blow-out preventor which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventor and the associated support structure, the support comprising a plurality of suspension members extending between the associated support structure and the support, where the suspension members are mounted to the support at angularly equidistant positions around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, the sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied.

Abstract: A modified casing coupling that includes a receptacle, or receptacles, for a modular burst disk assembly. The burst disk assembly is retained by threads or a snap ring and is sealed by the retaining threads, or an integral o-ring seal. The. The disk fails at pressure specified by the user but before trapped annular pressure threatens the integrity of the outer casing. The design allows for the burst disk assembly to be installed on location or before pipe shipment.

Abstract: A method for preventing critical annular pressure buildup in an offshore well utilizes a modified casing coupling that includes a receptacle, or receptacles, for a modular burst disk assembly. The burst disk assembly is retained by threads or a snap ring and is sealed by the retaining threads, or an integral o-ring seal. The disk fails at pressure specified by the user but before trapped annular pressure threatens the integrity of the outer casing. The design allows for the burst disk assembly to be installed on location or before pipe shipment.

Abstract: An apparatus for controlling a blowout preventer stack. The apparatus comprises a control pod having a plurality of direct operated solenoid valves in electronic communication with a surface controller through one or more dedicated electronic control wires. The solenoids translate electronic control signals from the controller into hydraulic control signals that are in communication with a hydraulically operated pilot valve to cause delivery of hydraulic fluid from a power fluid source to a critical function of the blowout preventer stack (i.e., closing of a blowout preventer). The system also provides a plurality of hydraulically operated pilot valves that deliver hydraulic fluid from a power fluid source to a non-critical function of the blowout preventer stack upon receiving a hydraulic control signal directly from the controller through the umbilical.

Abstract: A slimbore marine riser and BOP are provided for a subsea completion system which includes a tubing spool secured to a wellhead at the sea floor. The tubing spool has an internal landing profile for a reduced diameter tubing hanger which is arranged and dimensioned to pass through the bore of the riser and BOP at the end of a landing string. The tubing hanger, arranged and designed to be sealingly positioned in the tubing spool landing profile, has a production bore and a relatively large multiplicity of electric and hydraulic passages which terminate at a top end of the hanger with vertically extending electric and hydraulic couplers. A passage is provided through the body of the tubing spool which provides communication from above the tubing hanger to the well annulus below the hanger. A remotely controllable valve is placed in the annulus bypass passage.

Abstract: A method for controlling a subsea well that includes shutting at least one blowout preventer, opening at least one isolation line, and circulating an influx out of a well while an inlet pressure of a subsea mudlift pump is adjusted to maintain a substantially constant drill pipe pressure at an initial circulating pressure. After the influx is circulated out of the well, drilling mud with a kill mud weight is pumped into the well. The drill pipe pressure is reduced according to a preselected drill pipe pressure decline schedule until the kill mud weight drilling mud reaches the bottom of the well. The drill pipe pressure is then maintained at a final circulating pressure by adjusting the inlet pressure of the subsea mudlift pump. The kill mud weight drilling mud is then circulated from the well bottom to the surface at the final circulating pressure.

Abstract: A method for detecting a leak in a drill string valve used when drilling a subsea well. The method comprises measuring a first inlet pressure at a subsea mudlift pump while a subsea mudlift pump and a surface pump are operating and before a well is fully shut-in and measuring a second inlet pressure at the subsea mudlift pump after the mudlift pump and the surface pump are shut down and after the well is fully shut-in. The first and second subsea mudlift pump inlet pressure measurements are then compared, and a check is performed to determine if the subsea mudlift pump inlet pressure has increased by an amount greater than an estimated annular friction pressure.

Abstract: A method for a dynamic shut-in of a subsea mudlift drilling system. The method comprises detecting a kick, isolating a wellbore, and adjusting a subsea mudlift pump and a surface mud pump to provide a selected wellbore pressure. Selected well parameters are measured and used to calculate a kick intensity.

Abstract: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The buoyancy tank or housing includes an annularly shaped flange positioned on its upper end and retained by explosive bolts. The inner circumference of the flange is sealed to the riser section supported by the buoyancy housing. A sensing means, activated by a parting of the riser, actuates the explosive bolts to release the annularly shaped flange and flood the buoyancy housing while restraining lines limit movement of the buoyancy housing with respect to the riser section.

Abstract: A method and apparatus for improving reservoir communication includes, in one arrangement, use of one or more chambers to create an underbalance condition and/or a fluid surge in the wellbore. In another arrangement, a tool string comprises a packer, a circulating valve, and an atmospheric chamber, in which the circulating valve, when open, is adapted to vent a lower wellbore region below the packer when the packer is set, and the atmospheric chamber is capable of being operated to create an underbalance condition below the packer. In yet another arrangement, an apparatus comprises a subsea wellhead equipment including a blow-out preventer, choke line filled with a low density fluid, and a kill line filled with a heavy fluid. The choke line is adapted to be opened to create an underbalance condition in the wellbore.

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: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The rapid venting of the compressed air ensures that the riser section cannot rapidly ascend to the surface and damage the drilling rig positioned above. In a first embodiment, the buoyancy tank or housing includes a circumferentially shaped channel positioned on its upper end. An annularly shaped ring is placed over the circumferentially shaped channel and sealed in place by a frangible weld. A tether line attaches to the annularly shaped ring and extends to an anchor point on the BOP stack below. In the event of a catastrophic parting of the riser, as the riser sections and attached buoyancy tank or housings begin ascending, the tether line is drawn tight.

Abstract: A method for installing a string of tubing in a subsea well has a provision for killing the well due to malfunction while the tubing is being installed. A running tool is attached to a tubing hanger located at the upper end of the string of tubing. A completion safety module secures to the running tool and to a monobore running string. The assembly is lowered through a riser into the well, with the tubing hanger landing in a production tree. After the tubing hanger has been secured to the tree, earth formation pressure is communicated to the interior of the string of tubing while the running tool still remains connected to the tubing hanger. If a problem occurs, and the valves of the completion safety module fail to open, rams of the riser blowout preventer are closed around the running tool. The running tool is then disconnected from the tubing hanger and allowed to move upward a short distance due to pressure in the well.

Abstract: An accumulator for use in deepwater operational and control systems which uses a differential between a high pressure ambient pressure source such as sea water pressure and a low pressure source such as a chamber holding vacuum or atmospheric pressure to provide storage and delivery of hydraulic power for operation of equipment.

Abstract: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The rapid venting of the compressed air ensures that the riser section cannot rapidly ascend to the surface and damage the drilling rig positioned above. In a first embodiment, the buoyancy tank or housing includes a vertical channel positioned on its exterior. A cover plate is placed over the vertical channel and sealed in place by a frangible weld. A tether line attaches to the cover plate and extends to an anchor point on the BOP stack below. In the event of a catastrophic parting of the riser, as the riser sections and attached buoyancy tank or housings begin ascending, the tether line is drawn tight. Further ascension of the buoyancy tank or housings, causes the frangible weld joints to break and peel back the cover plate, exposing the vertical channels.

Abstract: A method and apparatus for temporarily storing the lower portion of a string of drill pipe in a well which has a cased portion wherein a packer, installed between a storm valve located below the packer and an actuator located above the packer, is set in the annulus between the drill pipe and the well casing, the actuator being designed to close the valve upon initial axial movement of the upper portion of the drill pipe, and then to become disengaged from the lower portion of the set drill pipe allowing the remaining surface suspended drill pipe and actuator to be retrieved as in the case of a floating drill ship or set aside for reconnection and reopening of the storm valve after a storm has passed.

Abstract: The present invention provides apparatus and method for killing or suppressing a subsea wellbore. The system includes a pressure intensifier adjacent the wellhead. The output of the pressure intensifier is coupled to a “kill” inlet at the wellhead equipment. Power is supplied from the surface to the pressure intensifier, which increases the pressure by a known multiple, usually 3 to 5, and supplies the high pressure fluid to the wellbore. A control unit at the surface controls the operation of the pressure intensifier in response to the predefined criteria or programmed instructions. One or more sensors provide measurements to the control unit of the wellbore conditions, which are used to determine the timing of activation of the pressure intensifier.

Abstract: There are disclosed two types of valves connectible in a subsea drilling riser to permit the opening and closing of side ports therein. One such valve is automatically opened when the hydrostatic subsea pressure is greater by a predetermined amount than that of drilling mud in the riser. The other valve is installed in the lower end of the riser and is adapted to be opened to discharge drilling fluid therefrom.

Abstract: A caisson wellhead system having a weak point wherein the wellhead system may be installed in a well as a single unit. The caisson wellhead system of the invention includes a lower tubular member having an upper rim. A lower rim of an upper tubular member is placed on the upper end of the lower tubular member. A removable connector is installed inside of and between the lower tubular member and upper tubular member for temporarily connecting the upper tubular member and the lower tubular member. A weak point is formed at the interface between the lower tubular member and the upper tubular member when the removable connector is removed. Therefore, the caisson wellhead system will break at a controlled location if any external components of the well equipment are struck by a foreign object such as an iceberg.

Abstract: A blowout preventer control system has been developed with a pod with features which include a retractable internal stab with fixed internal hydraulic connection lines to the blowout preventer. The hydraulic connection lines are connected by pressure activated packer seals. The stab also has an electrical connector to the blowout preventer which uses a guide which proper aligns the pins of the connector without any rotation. The piping of the control system uses an adjustable length type tubing to reduce the binding on the pipe. A lost motion float is used reduce the loading on the connection bolts of the system. The entire system is enclosed with plates with keep the expended hydraulic fluid in contact with the internal mechanisms. The transducers and seal subs are located for easy accessibility with no disruption of the surrounding elements of the system.

Abstract: An emergency recovery system designed for use in a subsea environment is disclosed. The emergency recovery system has a casing that is open at each end with a shackle connected to one end of the casing with the opposite end of the shackle designed for connection to appropriate points on the main stack and lower marine riser package in any orientation. A flexible sling with a closed loop formed at each end is used with one of the closed loops releasably connected to the shackle and the end of the casing. The other end of the sling has a flotation member attached to the sling adjacent the closed loop. The sling is fan folded as it is lowered into the casing. The flotation member is shaped to fit inside the other end of the casing with the closed end loop of the sling protruding from the casing. A split retaining ring is placed around the sling between the flotation member and the closed loop and inserted in the open end of the casing.

Abstract: A control system for wild oil and gas wells etc. using a centered, angled tubular device placed over and attached to the well head by clamps and remotely controlled hydraulic cylinders. The discharge of the well is directed into the bottom of the device, having movable blades forming two apertures used to minimize the induction of air from the exterior. Inert gas from engines powering pumps is injected into the space between the apertures, so that greater than atmospheric pressure in this chamber will result in the outflow of inert gas and prevent induction of air. Inert gas can also be injected into the main body of the device when required to prevent combustion. High pressure motive fluid is discharged from nozzles within the angled chamber of the device, directing the oil and liquids which impinge on the upper surface of the tube to be directed by baffles to its bottom, then flowing into a collecting trough and drawn through slots in the trough bottom by fluid jet eductors.

Abstract: Fire protection for the tensioner cylinders of a marine riser tensioner system in oil and gas offshore drilling and production rigs where the tensioner cylinders are coated with intumescent epoxy and their respective cylinder rods are enclosed within outer fire protection cylinders which comprise an inner metal lining and an outer jacket. The outer jacket comprises an inner multi-layer thick blanket of ceramic fibrous materials and barrier films contained within inner and outer layers of woven ceramic fibers for reinforcement and abrasion resistance. The outer fire protection cylinders telescope over the tensioner cylinders as the cylinder rods extend and retract in response to vertical movement of the rigs. The intumescent epoxy on the tensioner cylinders are covered with a bearing sleeve to provide a smooth surface for the telescoping fire protecting cylinders and fire retardant mechanisms are located at the tops and bottoms of the telescoping cylinders to prevent intrusion of heat and flame.

Abstract: A passive fire protection system for the protection of articulating joints and flexible connections against flame and heat in a severe total environment type fire such as a hydrocarbon fire which includes multi-layered flexible protective covers on articulating joints and flexible connections. These multi-layered flexible covers comprise an outer section of one or more layers of cloths, the outer section being of an abrasion resistant, weatherproof outer layer, with a woven ceramic fiber to resist flame impingement, and reinforcement mesh and stitching as required. The inner section is a thick interior multi-layered composite blanket of ceramic fibrous materials, barrier films, and an inner layer of abrasion resistant cloth to minimize heat transfer to the articulating joint or flexible connection. The thickness of the interior layer is determined by the mass being protected and the height of the allowable temperature for a particular fire rating.

Abstract: An anchor system for temporarily anchoring the lower end of a lower marine riser package (LMRP) assembly, drilling riser, and drill string used in drilling subsea wells. The anchor system includes a dummy wellhead secured to the ocean floor and weight means stored in a dummy wellhead that can be connected to the end of the drill string in a manner that restrains the lateral movement of the LMRP assembly, drilling riser, and drill string.

Abstract: An enclosed protective chamber for a subsea wellhead assembly includes a main body installed on the sea floor. Subsea wellhead apparatus is mounted in the chamber on top of a well. A pressure-containing lid is mounted on and sealed with respect to the main body such that chamber pressure is isolated from the subsea hydrostatic head. An inflatable, elongated, flexible storage tank or dracon is attached to the chamber through a conduit having a pressure-balanced relief valve therewithin. The dracon is attached to the conduit through a quick disconnect coupling and closure valve which permit ready attachment, removal, or replacement of the dracon. Under normal operating conditions the dracon is deflated. The dracon is preferably anchored to the sea floor. When a leak in the subsea wellhead assembly occurs, excess chamber pressure permits surplus fluid to enter and fill the dracon.

Abstract: The specific embodiment comprises a valve piston mounted on a shaft that is slidably disposed within an aperture in the lower housing of the blowout preventer. The valve piston and shaft may be extended into the central passage of the BOP in an open position through the use of a hydraulic operator assembly. When the valve piston and shaft have been extended into the open position, the wellbore gases enter into the annular space between the shaft and the aperture through the lower housing of the BOP. The wellbore gases are then vented from the aperture through an open vent conduit to the outside of the BOP.The hydraulic operator assembly is spring biased to keep the valve piston and shaft in closed position whenever the hydraulic operator assembly is not activated. The valve piston will therefore automatically close whenever there is a loss of hydraulic control. In normal operation, the hydraulic operator assembly will keep the valve piston and shaft in open position until the wellbore gases have been vented.