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: A process to manufacture an oilfield component comprises selectively reinforcing a base material with an age-hardenable clad material and age-hardening the clad material for a selected time and at a selected temperature profile, wherein the age-hardening results in the clad material developing a selected strength gradient. A body of a ram blowout preventer comprises, a low-ally base material, a vertical bore through the body, and a horizontal bore through the body intersecting the vertical bore, wherein at least a portion of the body is selectively reinforced with a clad material, and wherein the clad material is age-hardened for a selected time and at a selected temperature profile resulting in the clad material developing a selected strength gradient.

Abstract: The present invention relates to overpressure protection systems and methods for use on a production system for transferring hydrocarbons from a well on the seafloor to a vessel floating on the surface of the sea. The production system includes a subsea well in fluid communication with a turret buoy through a production flowline and riser system. The turret buoy is capable of connecting to a swivel located on a floating vessel. The overpressure protection device is positioned upstream of the swivel, to prevent overpressure of the production swivel and downstream components located on the floating vessel. The device may include one or more shut down valves, one or more sensors, an actuator assembly, and a control processor.

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

Abstract: An apparatus that is usable with a well includes an power converter and a controller. The power converter translates electrical power into hydraulic power downhole in the well to generate a first hydraulic signal to cause a downhole tool to transition to a first state and a second hydraulic signal to cause the tool to transition to a different second state. The controller responds to stimuli that are communicated from the surface of the well to cause the actuator to generate one of the first and second hydraulic signals.

Abstract: A safety valve system includes a safety valve having an actuator and a line connected to the actuator. The safety valve is operable by opening the line in the well, with the line being free of any connection to a surface control system. Another safety valve system includes multiple safety valves. An actuator of each safety valve is connected to an actuator of another safety valve via a line. A biasing force in each of the actuators is operative to close the respective one of the safety valves in response to opening of the line. The biasing force is produced at least in part by hydrostatic pressure in a well.

Abstract: An embodiment of a method for limiting the probability of failure on demand of a subsea test tree (“SSTT”) includes the steps of providing a safety shut-in system for actuating a safety valve of the SSTT, the safety shut-in system including a surface control station positioned above a water surface connected via an umbilical to a subsea control system positioned below the water surface to actuate the safety valve; and diagnostically testing the safety shut-in system without actuating the safety valve.

Abstract: A completion system, and a corresponding method, for completing a subsea well, where the well includes a wellhead and a tubing hanger disposed in the wellhead and supports a string of production tubing, allows for angular alignment-free assembly of the subsea well. The completion system includes a series of circumferential channels formed in a well completion device at a boundary between the tubing hanger and the well completion device. The circumferential channels provide complete circular fluid paths with respect to the tubing hanger and the well completion device. At least one supply bore is in communication with each circumferential channel and is and oriented to supply a fluid to the circumferential channel, and at least one drain bore in communication with each circumferential channel and is oriented to remove fluid from the circumferential channel. Finally a circumferential electrical connector couples the tubing hanger and the completion device.

Abstract: The present invention discloses apparatus and methods for a lightweight subsea intervention package that may be installed using vessels with a smaller lifting capacity than semi-submersible platforms so that the subsea intervention package can be transported, installed, and removed from a subsea well in less time and with less cost. In one embodiment, the present invention comprises a lower riser package for controlling the subsea well which utilizes two hydraulically activated gate valves. An emergency disconnect package is secured to the lower riser package utilizing a disconnect mechanism. The emergency disconnect package is operable to seal the bottom of a riser if the disconnect mechanism is activated to thereby minimize environmental leakage of fluid from the riser.

Abstract: An all electric subsea tree can be coupled with a hydraulic pressure unit that is fed off electrical and control lines that are in the umbilical from the surface. In that way hydraulic lines do not need to be separately run from the surface to the tree. Alternatively hydraulic pressure can be generated at a downhole tool using power and control lines running from the tree to the downhole equipment. As another alternative, the downhole equipment can be run by electric motor located downhole adjacent the downhole equipment and powered and controlled by lines running from the tree to the downhole location.

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

Abstract: A hybrid process control system including electrical transmission of power to a sub-sea hydraulic power unit, which in turn provides hydraulic power for control of hydraulic actuators. A circulation system using small bore tubing in the umbilical cord in combination with a traditional topside hydraulic power unit provides for active control of hydraulic fluid quality with respect to contamination caused by the sub-sea hydraulic actuators, especially process gas from down hole safety valves. Thus, a more economical power transmission is achieved without reduction of fluid quality, which is essential to system integrity and reliability. Also, a significant enhancement of power transmission without a dramatic increase in the size of hydraulic supply and return lines is achieved. Fluid environmental issues are reduced to a negligible aspect.

Abstract: A sensor and transmitter is employed with a pressurized chamber of a downhole tool to be able to tell at a glance when the tool is delivered for service that it is properly charged. The sensor and transmitter can be integrated within the tool so as to be protected from damage during run in. While in service the sensor and transmitter can monitor pressure in real time and include a capability to send surface signals for real time monitoring of chamber pressures corrected for the service depth, temperature and density of the hydraulic fluid, for example. The signal can be acoustic through the control line or the annulus or delivered through a fiber optic cable or signal wire run in the hydraulic control line, an auxiliary line or through the annulus.

Abstract: A riser control device, particularly designed to be used in connection with spool or horizontal production trees (12) for wells in sub-sea oil and gas installations. Within a housing (1,2) of the device is provided, in opposed direction, radially movable pair of rams (6) for isolating (sealing off) the well and simultaniously, in opposed direction a radially movable pair of shear blades (7) for cutting off an intervention string or the like. The rams (6) and blades (7) are driven by means of a vertically disposed actuator (8,9,23) integrated in the housing (1, 2). The actuator may be in the form of a hydralically driven annular piston (23)/annular chamber (29,30) device, which via piston rods (14) and translation beams (8) transforms the movement of the piston (23) to open or close the rams (6) and shear blades (7).

Abstract: The present invention relates to overpressure protection systems and methods for use on a production system for transferring hydrocarbons from a well on the seafloor to a vessel floating on the surface of the sea. The production system includes a subsea well in fluid communication with a turret buoy through a production flowline and riser system. The turret buoy is capable of connecting to a swivel located on a floating vessel. The overpressure protection device is positioned upstream of the swivel, to prevent overpressure of the production swivel and downstream components located on the floating vessel. The device may include one or more shut down valves, one or more sensors, an actuator assembly, and a control processor. Each shut down valve and sensor is coupled to a production flowline. Each of the sensors is capable of generating a signal based upon a pressure sensed within the production flowline. The actuator assembly is connected to each of the shut down valves for operating the shut down valves.

Abstract: A method and apparatus for drilling subsea wells is provided. A subsea shut off device including ball gripping mechanisms is latched to a template at surface. Drilled in casing can be suspended from the device at any position using the gripping mechanism so that the device is run to the sea floor on the casing string. The casing string is drilled into place and converted into a riser. This is all done on a single trip to speed up the operation and reduce the risk. The casing string is captured and sealed within the subsea shut-off device after installing and spacing out a surface BOP. For the event when emergency disconnection is required, dual shear rams in the device cut the casing and seal in the well. The system then allows a conventional subsea reconnection of the riser.

Abstract: A system for controlling gas in a subsea drilling operation is disclosed in one embodiment. The system includes a subsea blow-out preventer, riser coupled to the blow-out preventer, a gas sensor, a controller, and a signal pathway. The gas sensor is configured for placement below the riser and configured to contact wellbore fluids during normal drilling operation. The controller configured to automatically cause manipulation the blow-out preventer based upon information from the gas sensor. The signal pathway couples the gas sensor with the controller.

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: A process to manufacture an oilfield component comprises selectively reinforcing a base material with an age-hardenable clad material and age-hardening the clad material for a selected time and at a selected temperature profile, wherein the age-hardening results in the clad material developing a selected strength gradient. A body of a ram blowout preventer comprises, a low-ally base material, a vertical bore through the body, and a horizontal bore through the body intersecting the vertical bore, wherein at least a portion of the body is selectively reinforced with a clad material, and wherein the clad material is age-hardened for a selected time and at a selected temperature profile resulting in the clad material developing a selected strength gradient.

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 distributed function control module adapted for use in a modular blowout preventer (BOP) stack for use subsea comprises a housing, adapted to be manipulated by a remotely operated vehicle (ROV) with a stab portion adapted to be received into a BOP stack control module receiver. Control electronics, adapted to control a predetermined function with respect to the BOP stack, are disposed within the housing and connected to one or more controllable devices by a wet mateable connector interface.

Abstract: A distributed function control module adapted for use in a modular blowout preventer (BOP) stack for use subsea comprises a housing, adapted to be manipulated by a remotely operated vehicle (ROV) with a stab portion adapted to be received into a BOP stack control module receiver. Control electronics, adapted to control a predetermined function with respect to the BOP stack, are disposed within the housing and connected to one or more controllable devices by a wet mateable connector interface. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope of meaning of the claims.

Abstract: An air swivel ring includes a non-rotating member having an air inlet, a rotating member having an air outlet, and a split seal having a first sealing surface and coupled to one of the non-rotating member and the rotating member so that the first sealing surface on the seal is disposed proximate a second sealing surface on the other of the non-rotating member and the rotating member.

Abstract: A choke actuator having an integrated choke control system enabling fast closure and opening of the choke. The choke control system includes integral electronics to receive signals from a surface or subsea control module and control directional control valves to regulate the flow of hydraulic fluid from a local hydraulic supply to the choke actuator. Response times for choke actuation are greatly reduced by locating the electronic control system and directional control valves in an integrated package with the choke actuator and providing a local hydraulic supply. Additional embodiments may also include other electronic sensing and instrumentation enabling the choke control system to monitor and adjust the choke to maintain selected flow characteristics or in accordance with a predetermined production scheme. Any or all of the components of the choke, the choke control system, or the choke actuator may also be retrievable separately from the other components so as to allow maintenance and replacement.

Abstract: A technique for maintaining pressure integrity within a submersible system. The system utilizes a pressure housing with an internal component, such as a valve. The internal component is actuated by an external actuator via an actuator stem. A seal region is positioned to interact with the stem, such that the interior of the pressure housing is sealed and pressure integrity is maintained upon retraction of the stem from engagement with the internal component.

Abstract: A safety device 30 for compensating for ocean heave motion of a vessel or watercraft connected to a conduit 12 or drill string extending to the subsea. The safety device comprises at least one vertical piston and cylinder assembly 40,41, the piston rod 40a of which connects to an upper beam 35 of the device 30 and the cylinder 40b of which connects to a horizontal beam 42 below the upper beam 35 and supported by vertical tension legs 51,52, each including a gas expansion chamber 51a,52a. A valve controlled conduit system 61,62 connects the chambers 51a,52a and cylinders 40b,41b to a source of pressurized gas whereby a fixed volume of gas and gas pressure positions the pistons at the mid-lengths of the cylinders 40b,41b The safety device 30 is mounted on a frame or rig 11 mounted on the watercraft and the base 33 of the safety device 30 is connected to the bottoms of the tension legs 51,52.

Abstract: A modified casing coupling and burst disk assembly are used to prevent critical annular pressure buildup in an offshore well. The modified casing coupling 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: A method of enclosing an oil drilling rig. A first step involves providing a base and a flexible sheet-form covering having a first edge and second edge. A second step involves securing the base to the oil drilling rig and securing the first edge of the covering around a perimeter of the base. A third step involves securing the second edge of the covering to the drilling rig in spaced relation to the base, thereby maintaining the covering in a substantially taut condition forming a tubular enclosure.

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: The invention is a subsea umbilical termination assembly (UTA) for use with a launch system mounted on a vessel, wherein the UTA involves a lift point, a guide surrounding a connector attached to the lift point, a housing with a mandrel for engaging the connector and at least one interface, numerous flying leads connected to the housing, a base for the housing, and an emergency quick disconnect connected to the mandrel, wherein the disconnect has a hydraulic connector that engages hydraulic pistons that can then disengage numerous locking dogs enabling the hydraulic connector to disengage from the UTA, and wherein the interface in the housing connects to an electrical umbilical, a fiber optic cable, or hydraulic umbilical.

Abstract: A running string for a subsea completion comprises an upper section (70) which may be a coiled tubing (CT) injector unit as shown, or a wireline lubricator (FIG. 8). A lower section (60) provides wireline/CT access to production/annulus bores of a tubing hanger (not shown) attached to tubing hanger running tool (62). A flow package (64) in the lower section (60), together with BOP pipe rams (86) and annular seal (88), directs production and annulus fluid flows/pressures to the BOP choke/kill lines (78/76). The upper and lower sections allow installation and pressure/circulation testing of, and wireline/CT access to, a subsea completion, without the use of a high pressure riser.

Abstract: A protective covering for subsea well apparatus is provided. The covering is generally a pyramidal structure and includes blades at the corners extending below the base of the structure. The blades are sized to prevent snaring of objects dragged over the covering. The covering may be assembled from sections after transport over a public highway. Methods for transporting and installing the covering and achieving penetration of the blades into the seafloor are also provided.

Abstract: The present invention provides a safety shut-in system employed during testing, intervention, or other operations in wells. More specifically, the invention relates to a coiled tubing cutter for use with a safety shut-in system.

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 system for use with a subsea well that includes a BOP includes a fluid line and a tool that is not connected to the fluid line. The fluid line is connected to the BOP to communicate a pressure encoding a command, and the tool is adapted to decode and respond to the command when the tool is inside the BOP.

Abstract: A petroleum well having a communication system and a hydraulic system is provided. The petroleum well includes a borehole and a piping structure positioned within the borehole. The communication system supplies a time varying electric current downhole along the piping structure. The hydraulic system (70), which is positioned downhole proximate the piping structure (26), receives the time varying current to operate an electric motor (78). The motor drives a pump (76) which pressurizes hydraulic fluid to selectively drive an actuator (84). The actuator (84) is operably connected to a downhole device, such as a shutoff valve, and operates the downhole device as the actuator (84) is driven by the pressurized hydraulic fluid.

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: 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: A dummy undersea hydraulic coupling member is disclosed for protecting an opposing undersea hydraulic coupling member when the hydraulic lines are not operating. The dummy undersea hydraulic coupling member has a water displacement expansion chamber with a piston therein that allows trapped water and/or air to move from the receiving chamber to the water displacement expansion chamber during connection of the dummy coupling member to the opposing coupling member.

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: 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: 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 remotely installed pressure containing closure having a slight negative buoyancy, and a method for assembly of a slight negative buoyancy remotely installed pressure containing closure, such as a tree cap, on a subsea assembly, having at least one fluid bore, and more preferably a production bore and an annulus bore, wherein the remotely installed pressure containing closure comprises: a guidance ring having a plurality of chambers; optionally, a plurality of orientation pins affixed to the guidance ring for aligning the guidance ring to a funnel; buoyant material disposed in the chambers of the guidance ring to assist in creating a slight negative buoyancy for the remotely installed pressure containing closure; a cylinder connected to the remotely installed pressure containing closure for engaging sealing means on a subsea assembly for sealing at least one seal of at least one fluid bore of said subsea assembly; a debris cover connected to said cylinder to house equipment and cover the fluid bore; a mandre

Abstract: Apparatus and methods for suppressing vortex-induced vibrations (VIV) of aquatic elements of underwater structures. The system includes use of a sleeve positioned around at least a portion of an aquatic element and at least one strake positioned along at least a portion of the length of the aquatic member. The apparatus further comprises copper to suppress the growth of aquatic organisms.

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: 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.