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 load limiting break away arrangement for a subsea umbilical includes telescoping inner and outer bodies. The inner body includes multiple cross-bored holes; the outer body has slotted openings on its top and bottom sides. A shearing blade is positioned at one end of a top slot of the outer body. Individual umbilical tubes pass through a bottom slot of the outer body, through individual holes in the inner body and out a top slot of the outer body for attachment to multiple quick connect couplers on an umbilical termination head of an Umbilical Termination Assembly (UTA) and of an Electro-Hydraulic Distribution Module (EHDM). Tension resistant actuation members run between the UTA and EHDM so that when a snag of an umbilical occurs, the inner and outer bodies are pulled apart and the tubes are severed one by one by the blade of the outer body.

Abstract: The disclosure describes a spoolable compliant guide, a system including a spoolable compliant guide and injector and methods for using the compliant guide, where the guide is designed to connect at one end to the injector and at its other end to a remote installation having a seal and to allow coiled tubing to be inserted into the installation through the seal. Because the guide permits a substantial distance to exist between the injector and the installation seal and functions as a crimp or band resistor for the coiled tubing, the guide enables the injector to be conveniently positioned remote from the installation such as a wellhead and assumes a compliant shape between the injector and the installation allowing dynamic relative movement between them without the use of heave compensators. Thus, for subsea installations, the injector, its control system and coiled tubing reels can all be located on the water's surface for ease of access and maintenance.

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 method and apparatus for ensuring against explosion of the gaseous atmosphere of a closed chamber, such as the QDCD room of an internal turret of an offshore production and offloading buoy wherein the closed chamber has production risers and conduit connectors that represent a potential source of flammable gas. The method comprises mixing and diluting the oxidant content of the air by introducing within the closed chamber a sufficient quantity of inert gas to render the mixture of the air and any flammable gas non-combustible regardless of the flammable gas content of the mixture. The method includes removal of the non-combustible mixture of air and any flammable gas from the closed chamber by purging thereof to the natural atmosphere, while introducing inert gas, thereby leaving a substantially inert atmosphere within the closed chamber.

Abstract: A flow completion system for controlling the flow of fluid from a well bore, the flow completion system comprising a tubing spool which includes a central bore that extends axially therethrough and a production outlet which communicates with the central bore; a tubing hanger which is supported in the central bore and which includes a production bore that extends axially therethrough and a production passageway that communicates between the production bore and the production outlet, the tubing hanger supporting a tubing string which extends into the well bore and defines a tubing annulus surrounding the tubing string; a first closure member which is positioned in the production bore above the production passageway; a first annular seal which is positioned between the tubing hanger and the central bore above the production passageway; wherein the first closure member and the first seal comprise a first pressure-containing barrier between the well bore and a surrounding environment; a second closure member which

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 and method of operating devices (such as devices in a wellbore or other types of devices) utilizes actuators having expandable or contractable elements. Such expandable or contractable elements may include piezoelectric elements, magnetostrictive elements, and heat-expandable elements. Piezoelectric elements are expandable by application of an electrical voltage; magnetostrictive elements are expandable by application of a magnetic field (which may be generated by a solenoid in response to an electrical current); and heat-expandable elements are expandable by heat energy (e.g., infrared energy or microwave energy). Expandable elements are abutted to an operator member such that when the expandable element expands, the operator member is moved in a first direction, and when the expandable element contracts, the operator member moves in an opposite direction.

Abstract: An apparatus for retaining fluid in a pipe includes an elongated body adapted to be positioned within a subsea wellhead assembly. The elongated body has an end adapted for connection to the pipe, a flow passage for fluid communication with the pipe, and an outer surface for engagement with a sealing member in the subsea wellhead assembly. A first chamber is defined within the elongated body and connected to receive pressure from above the subsea wellhead assembly. A second chamber is defined within the elongated body and connected to receive pressure from below the subsea wellhead assembly. A valve is supported in the elongated body for movement in response to pressure differential between the first and the second chambers. The valve is movable between an open position to permit fluid flow through the flow passage and a closed position to prevent fluid flow through the flow passage.

Abstract: A rotary electric actuator module has a plurality of actuators for actuating a device in a subsea wellhead assembly. The module is arranged to receive primary power and control signals from an external source in order to actuate the subsea devices. Each actuator in the module has a back-up power supply, each power supply having a self-contained electrical storage unit providing a source of secondary power. Each actuator has a motor driven by the electrical storage unit. A control system is provided to detect the interruption of the primary power or the control signals and, if the subsea device is in an unsafe operating position, cause the subsea device to move into a safe position using the secondary power.

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: A drilling head used to seal around a drill pipe while drilling is employed in a subsea location. The drilling head has an inner body located within an outer body. At least one bearing is located between the outer body and the inner body for facilitating the rotation of the inner body relative to the outer body. A seal mounted to a lower portion of the inner body seals around the outer surface of the drill pipe. While lowering the drilling head to the wellhead, a support attached to the drill pipe is inserted into a skirt which surrounds a portion of the seal. The skirt and support are releasably connected using a J-slot mechanism. An inner annulus and an outer annulus are located between the inner and outer bodies, the annuluses containing a lubricating fluid. Helical vanes are located within the inner annulus and affixed to the inner body. The vanes rotate with the inner body for circulating the fluid through the inner and outer annuluses.

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 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: A quick connect/disconnect system for an offshore oil/gas production platform is facilitated by a submerged connection header for the platform. The platform comprises a vessel with a connection bay on vessel bottom. The vessel has the ability to be ballasted to position the connection bay either for connection or for transport toward and away from the connection header. The connection header houses the production lines and control lines and is positively buoyed and held in place by tension cables extending from the header bottom to the ocean floor. The quick connect/disconnect system comprises couplers for the production lines and control lines and devices for releasably linking the header to the vessel bay whereby the vessel may be held in a state of positive buoyancy by appropriately deballasting the vessel.

Abstract: An apparatus for performing workover operations on a subsea well that has a subsea production tree with a production passage and an annulus access passageway. The subsea production tree is secured to a lower riser portion. The lower riser portion connects to the tree and has a production passage which registers with a production passage of the tree. The apparatus also has an annulus access passage which registers with the annulus access passage of the tree. The apparatus further includes a monobore riser which extends downward from the surface. A string of tubing, preferably coiled tubing, extends through the monobore riser and defines an inner riser passage and an annular riser passage. A circulation plug is secured proximate a lower end of the coiled tubing and is landed in the lower riser portion of the subsea well. The circulation plug communicates the inner riser passage with the annulus access passage.

Abstract: A spanner joint assembly for connecting between an upper riser and a conventional dual bore tubing hanger in a subsea well. The spanner joint assembly includes upper and lower spanner joint portions connected to each other through an emergency disconnect portion. The upper spanner joint portion has a longitudinal production bore and a longitudinal annulus. The lower spanner joint portion has a longitudinal production bore with a production bore valve and a longitudinal nonconcentric annulus access bore. The emergency disconnect portion includes an upper mandrel connected to the upper spanner joint portion and a lower mandrel connected to the lower spanner joint portion. A releasable mechanical connector includes a retaining groove in the lower mandrel and a collet connected to the upper mandrel. The collet has a latching portion extending beyond the upper mandrel which is adapted to be received in the retaining groove.

Abstract: A downhole production well control system is provided for automatically controlling downhole tools in response to sensed selected downhole parameters. The production well having a production tubing string therein with multiple branches, i.e., zones, each including a downhole primary control system. Each primary control system includes electromechanical drivers and devices to control fluid flow. A redundant control system is associated with each of the primary control systems. Each redundant control system is the identical its corresponding primary control system. The redundant control system is set to a sleep or dormant mode, while the primary control system is set to an active mode for collecting data, and communicating with the surface. In the event of a failure, the primary control system is switched to an inactive mode and the redundant control system is switched to an active mode, whereby it will now collect data, and communicate with the surface.

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: A subsea test tree and associated methods of servicing a well provide enhanced safety in testing operations. In a described embodiment, a subsea test tree includes a latch head assembly, a valve assembly, and a ramlock assembly interconnected between the latch head assembly and the valve assembly. The valve assembly includes two safety valves, one of which is operable by displacing a piston within the latch head assembly. The other safety valve is operable by applying fluid pressure to a line connected to the latch head assembly.

Abstract: The invention provides a versatile blow-out preventer having a hydraulically activated bladder and a mechanically operated set of rams mounted in a single body, occupying a minimum of vertical space, and being adapted to operate whether or not there is equipment such as pump rods or cables in the well head.

Abstract: A flow control apparatus and associated methods of using provide enhanced longevity and reliability without requiring complex mechanisms. In a described embodiment, a choke for use within a subterranean well has a choke member set which may be opened by manipulation of an inner tubular cage. The inner cage is displaced from within an outer sleeve, which restricts fluid flow through ports formed through a sidewall portion of the inner cage. As the inner cage is progressively withdrawn from within the sleeve, the fluid flow through the ports is decreasingly restricted by the sleeve.

Abstract: A flow control apparatus and associated methods of using provide enhanced longevity and reliability without requiring complex mechanisms. In a described embodiment, a choke for use within a subterranean well has multiple trim sets which may be individually selected by manipulation of a sleeve relative to an inner tubular cage. In another described embodiment, a single trim set is provided. Additional features include provision of a separate valve to selectively permit or prevent fluid flow through the single or multiple trim sets.

Abstract: A retainer valve provides increased safety in wellsite operations. In a preferred embodiment, operation of the retainer valve may be responsive to control line pressure or to tubing pressure. The retainer valve response is controlled by several factors, among which are relative tubing and balance line pressures, and axial positions of a number of pistons relative to a tubular J-slot member. If the control and balance lines are disconnected, or otherwise unavailable for operation of the valve, it may still be operated by manipulation of the tubing pressure at the earth's surface. Thus, the valve may be opened in emergency situations in which the control and balance lines are unavailable, but operation of the valve is still needed in order to safely relieve trapped pressure in the tubing string and/or to kill the well, unlatch a subsea test tree, etc. The retainer valve is also useful as a lubricator valve.

Abstract: A retainer valve provides increased safety in wellsite operations. In a preferred embodiment, operation of the retainer valve may be responsive to control line pressure or to tubing pressure. The retainer valve response is controlled by several factors, among which are relative tubing and balance line pressures, and axial positions of a number of pistons relative to a tubular J-slot member. If the control and balance lines are disconnected, or otherwise unavailable for operation of the valve, it may still be operated by manipulation of the tubing pressure at the earth's surface. Thus, the valve may be opened in emergency situations in which the control and balance lines are unavailable, but operation of the valve is still needed in order to safely relieve trapped pressure in the tubing string and/or to kill the well, unlatch a subsea test tree, etc. The retainer valve is also useful as a lubricator valve.

Abstract: A retainer valve provides increased safety in wellsite operations. In a preferred embodiment, operation of the retainer valve may be responsive to control line pressure or to tubing pressure. The retainer valve response is controlled by several factors, among which are relative tubing and balance line pressures, and axial positions of a number of pistons relative to a tubular J-slot member. If the control and balance lines are disconnected, or otherwise unavailable for operation of the valve, it may still be operated by manipulation of the tubing pressure at the earth's surface. Thus, the valve may be opened in emergency situations in which the control and balance lines are unavailable, but operation of the valve is still needed in order to safely relieve trapped pressure in the tubing string and/or to kill the well, unlatch a subsea test tree, etc. The retainer valve is also useful as a lubricator valve.

Abstract: A retainer valve provides increased safety in wellsite operations. In a preferred embodiment, operation of the retainer valve may be responsive to control line pressure or to tubing pressure. The retainer valve response is controlled by several factors, among which are relative tubing and balance line pressures, and axial positions of a number of pistons relative to a tubular J-slot member. If the control and balance lines are disconnected, or otherwise unavailable for operation of the valve, it may still be operated by manipulation of the tubing pressure at the earth's surface. Thus, the valve may be opened in emergency situations in which the control and balance lines are unavailable, but operation of the valve is still needed in order to safely relieve trapped pressure in the tubing string and/or to kill the well, unlatch a subsea test tree, etc. The retainer valve is also useful as a lubricator valve.

Abstract: A drilling, production, test, and oil storage caisson for use in deep water offshore well operations. Separate low pressure and high pressure drilling risers are independently supported on buoyancy modules. Multiple drilling and production risers are left in the water and connected to the drilling rig and well(s) as needed to prevent the need for the raising and lowering of different risers during the various steps involved in beginning and completing wells. Surface and lower BOP stacks are utilized. Means for controlling the accelerations and velocity of the drilling riser buoyancy modules in the event of riser failure is provided. A subsea tree with dual master valves allows for production directly through a vertical production riser, flowline, to the production manifold on the caisson. A twisted tubing production riser is formed from three strings of tubing that are used for the flowline, annulus, and conduit for control lines.

Abstract: Apparatus and a method for killing a live well after activation of a well blowout preventer is described. This is achieved by providing apparatus in the form of a shear or kill sleeve (34) in a string (26) above a sub-sea test tree and which is located between the pipe rams (22, 24) and shear rams (18) of a blowout preventer (12). In the event that the shear rams (18) are activated and seal the string above the kill sleeve (34), the sleeve includes a pressure sensitive valve (84) which may be opened, by pressurising between the blowout preventer rams (18, 22), to permit fluid to be pumped from the blowout preventer (12) through the valve (84) and into the string (40), to choke or kill the well. After the well has been killed, the blowout preventer (12) may be opened to permit removal of the well tools. Embodiments of the invention are described.

Abstract: Installed in the tubing string portion of an offshore well rig are a vertically spaced pair of tubular well line protective devices. The upper device extends vertically through the openings in the rig floor and the rotary table thereon, and the lower device is positioned between a pair of sealing rams within an open upper end portion of the riser through which the tubing downwardly extends. Each protective device has a main body portion which is radially enlarged relative to the balance of the tubing string, and a removable side insert portion. Well lines, such as control, chemical and balancing lines, are extended through axial openings combinatively defined by each body and associated insert, with the insert shielding the lines from damage at the protective device location. The removable insert is illustrated in an all metal construction, used in the upper device, and an all elastomeric material construction or an elastomer-faced metal construction used in the lower device.

Abstract: A retainer valve provides increased safety in wellsite operations. In a preferred embodiment, operation of the retainer valve may be responsive to control line pressure or to tubing pressure. The retainer valve response is controlled by several factors, among which are relative tubing and balance line pressures, and axial positions of a number of pistons relative to a tubular J-slot member. If the control and balance lines are disconnected, or otherwise unavailable for operation of the valve, it may still be operated by manipulation of the tubing pressure at the earth's surface. Thus, the valve may be opened in emergency situations in which the control and balance lines are unavailable, but operation of the valve is still needed in order to safely relieve trapped pressure in the tubing string and/or to kill the well, unlatch a subsea test tree, etc. The retainer valve is also useful as a lubricator valve.

Abstract: In an offshore oil installation, the closure device (40) of a subsurface test tree placed in the blowout preventer stack on the seabed is made in a modular manner. More precisely, the closure device comprises a plurality of lengths (54,56') suitable for being placed in arbitrary order between a top element (50) and a bottom element (52). This arrangement makes it possible to place the connector (46) between the total shutoff valves (26) and the partial shutoff valves (28) of the blowout preventer stack, and to place the valves (42,44) of the closure device (40) in a closure length (54) that is situated beneath the partial shutoff valves (28). The two total shutoff valves (26) can thus be actuated regardless of the type of blowout preventer stack that is used.

Abstract: There are disclosed two embodiments of subsea wellhead apparatus each of which includes a subsea wellhead housing installed at the ocean floor, a casing hanger connectable to the to the upper end of a casing string and supported in the bore of the housing to suspend the casing string in the well bore, and a tubing hanger connectable to the upper end of a tubing string and also supported within the housing bore above the casing hanger for suspending the tubing string within the casing string. A primary valve and a secondary backup valve are installed in series for controlling a passageway in the tubing hanger, and during the completion process, with an additional passageway in a Christmas tree which is installed on the head above the tubing hanger.

Abstract: This invention relates to well-head structures, and particularly to so-called christmas trees, i.e. the complex of valves and pipes installed at a well-head to control the flow of high pressure oil or gas. The invention more particularly, but not exclusively relates to such structures for use in sub-sea structures. In order to accommodate all the required valves and pipes, known trees are normally undesirably high--i.e. of the order of 18 feet or so. In order that trawler nets do not snag on such trees, expensive protection structures or well reinforcing may be required to be installed around each tree. However, the present invention provides a christmas tree including a valve assembly comprising one or more valves installed at a well-head to control the flow of produce thereat, at least one of the one or more valves being retained within an outlet of the well-head.

Abstract: A method and apparatus for controlling a production facility containing a well that produces subterranean fluids and gas is disclosed. The production facility is connected to a receiving facility by a pipeline having a pipeline pressure. The production facility has a remote control system that has operably associated therewith a controlling valve member, and a safety system containing a surface valve, and a subsurface valve. Generally, the method comprises the steps of setting the following pressures: a pipeline high pressure level, a pipeline low pressure level, a control system upper pressure level, and a control system lower pressure level. Next, the receiving facility is shut-in, and the pipeline pressure is monitored. According to the pressure level achieved in the pipeline, a signal in response thereto is generated, and thereafter a remote control system valve member may be activated thereby closing the valve.

Abstract: A blow-out prevention device shuts off an annulus between a drill column and a well wall by means of an expandable sealing device when an unwanted blow-out of fluid and/or gas takes place from an unstable geological well formation when drilling for oil or gas.When a blow-out takes place, a compressive-pulse code is activated in the inlet of the drill column and is transmitted through the drilling fluid to a pressure sensor which transmits the compressive-pulse code on to a microprocessor (37) which is preprogrammed with the pressure code. If the pressure codes coincide, an electric motor is activated, which, via a set of gears and a nut-and-bolt device, displaces a valve plate axially towards a valve seat. The drilling fluid then flows out through nozzles and causes a large pressure drop which is used to expand the sealing device so that the annulus is shut.

Abstract: A modular subsea control pod assembly having a retrievable pod assembly and a receptacle assembly. The retrievable pod assembly has a stab block and at least one function port having an opening in the stab block. The retrievable pod assembly includes a pod gate which is adapted to move between a first position in which the pod gate covers the function port opening and a second position in which the pod gate does not cover the function port opening. The receptacle assembly includes a receptacle base module adapted to receive the stab block and a receptacle function port adapted to be connected to a blowout preventer hydraulic operator. The receptacle assembly includes a receptacle gate which is adapted to move between a first position in which the receptacle gate covers the receptacle function port opening and a second position in which the receptacle gate does not cover the receptacle function port opening.

Abstract: System for remotely controlling the start-up of a closed-in well. A radio signal transmitted to the well actuates a main flow control valve to provisionally commence flow from the well into a conduit. During the provisional period, a comparator electronically analyzes the well's immediate operating pressure against a preferred operating parameter, and generates a signal representing the difference between the two. A generated signal further initiates such commands as will sustain well flow if the latter is within the preferred operating parameters, or after the brief provisional operating period, discontinues flow if necessary.

Abstract: A cased suspended sub-sea well is secured for abandonment by setting a packer in the casing thereof, the packer having a perforating gun suspended therefrom firing the gun to perforate the casing and then injecting cement into the annulus behind the casing.

Abstract: In a subterranean well for producing a production fluid flow through a flow line having a main control valve, a flow control system including means to remotely actuate the main flow valve to open position in response to a radio signal subsequent to the main valve being closed under elective or emergency conditions. Initial fluid flow from the well is commenced by provisionally opening the main flow regulating valve for a predetermined time interval. During said timed interval, if the pressure in the well flow line is not stabilized to an acceptable operating range, the main flow valve will be automatically closed in response to a pressure sensing means which communicates said main flow line with the main valve actuator.

Abstract: An electro-hydraulic control system for subsea wellheads provides a water tight housing carrying therewithin an electric motor drive which operates a valve that is positioned adjacent but outside the water tight housing. A high ratio gear box within the water tight housing interfaces the motor drive and the valve while maintaining the flow control position of the valve such as open flow, closed flow, or incremental flow opening positions of the valving member. A dual tone multi-frequency controller activates the electric motor drive using a key pad at a remote location so that both operation of the valve and an indication of valve position can be achieved from the remote location.

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.

Abstract: An offshore oil production and mooring system comprises a subsea well head production system connected to a subsea base located on the sea bed. A subsea restraining buoy is located at a position below the sea surface but above the sea bed. The buoy is pivottally connected by a flexible lower support line to the subsea base and by a flexible upper support line to a buoyant riser endpiece adapted for connection to a loading vessel. The endpiece is located in its rest position at a position below the sea surface but above the sea bed and is anchorable to the sea bed. A flexible production riser rises from a subsea connector to the production system to the subsea restraining buoy and is supported by the lower support line. The riser then passes over the buoy and so to the riser endpiece, this section of the riser being supported by the upper support line.

Abstract: An underwater sub-surface safety valve block is connected between a well head located at the sea bottom, and the lower end of a riser. This allows the production tube and/or the service tube of the completion string to be closed by means of gate valves. This sub-surface safety valve block comprises a valve body provided with a vertical through-bore tightly closed at its upper end by a packer to which the upper portion of the completion string is connected. The bottom is tightly closed by a tubing hanger to which the lower portion of the completion string is connected. The packer and the tubing hanger are fastened inside the through-bore by means of a mechanical hooking which can be disengaged by means of a hydraulic controlled action. They are each provided with a through-channel in order to connect the respective production tubes with the central region of the through-bore, which can be closed by means of a gate valve.

Abstract: An artificial submerged structure and underwater wellhead protection system for sheltering a submerged, permanently or temporarily abandoned wellhead utilizing a sloped structure configured to prevent nets, anchors, and the like from entangling or otherwise damaging the wellhead. The exemplary embodiment of the present invention is in the form of a pyramidal structure which is designed to rest on the sea floor, enveloping the wellhead. The present invention is prefabricated and designed to be assembled on the vessel above the well site before installation on the sea floor. The wellhead protector is designed to protect the wellhead from any anchoring, trawling or related activities, as well as protecting any nets or the like from becoming damaged due to entanglement with the wellhead. Anchoring means is also disclosed for providing a firm placement of the shelter relative the wellhead in those cases where large anchors, oyster dredges, trawl boards and the like might tend to knock over the structure.

Abstract: An annulus shut-off mechanism with fail-as-is logic suitable for use for example, in a concentric tubing hanger of an oil well, particularly a sub-sea well, has an enclosure across the annulus with inlet and exit ports, a sleeve with an aperture that slides within the enclosure, primary means for sliding the sleeve in the enclosure to bring the aperture into alignment with the inlet and exit ports and secondary means for sliding the sleeve in the event of failure of the primary means. The primary enclosure and sleeve are sealed from access to annulus fluids and may be vertically orientated in the tubing hanger. The secondary means may be a secondary enclosure with a secondary sleeve which can pull or push on the primary sleeve. Both primary and secondary means can be operated by hydraulic pressure, but the two means are independent and the secondary means may be located in a well part other than the tubing hanger.

Abstract: A hydraulic control system for controlling a retainer valve in an underwater well test system. The control system is contained in a housing in the test string above the retainer valve. The control system and valve are operated by a surface control manifold via control conduits extending between the manifold and control system housing. The system provides opening and closing and very quick closure of the retainer valve by eliminating the requirement for closing pressure to be conducted through a long conduit from surface and by utilizing well pressure to close the valve and lock the valve closed. One embodiment of the control system requires a pressure pulse from surface to start quick retainer valve closure. Another embodiment of the control system monitors control conduits for loss of pressure while the retainer valve is open and automatically closes the valve on loss of control pressure.

Abstract: An apparatus T.sub.1 for sealing a well tubing 12 including a housing 20, 21, 22 which has a channel 68 communicating with the bore of tubing 12 and a chamber 43 connected with channel 68. A seal 62 is slidably mounted in the housing and is disposed in a retracted open condition in chamber 43 to enable fluid flow through channel 68. AN actuator 41, 42 also disposed in chamber 43, includes a shape memory alloy material which is responsive to the temperature thereof rising to a predetermined level corresponding to the transition temperature of the shape memory alloy for transforming in shape to extend the seal into an extended condition within channel 68, thereby blocking fluid flow therethrough.

Abstract: A system is disclosed which may alternatively be used as a diverter or as a blowout preventer for a drilling rig. The system comprises a blowout preventer attached above a spool having a hydraulically driven sleeve/piston. An outlet flow passage in the spool, which may be connected to a vent line, is closed off by the sleeve wall when the spool piston is at rest.Hydraulic ports are connected above and below the blowout preventer annular piston and above and below the spool annular piston. The ports below the blowout preventer piston and above the spool piston are in fluid communication with each other. A hydraulic circuit is provided having two valves between a source of pressurized hydraulic fluid and a drain.