1. Field of the Invention
This invention relates in general to offshore drilling, and in particular to equipment and methods for running conduit with an offshore rig.
2. Background of the Invention
When drilling subsea wells, a low pressure wellhead housing is installed with a string of conductor casing or pipe extending therefrom into the sea floor. A high pressure wellhead housing is then landed in the bore of the low pressure wellhead housing with another string casing extending therefrom to a deeper depth. Additional strings of casing that extend deeper into the subsea well, until at least one string reaches a production depth, are suspended from casing hangers landed within the bore of the high pressure housing. A tubing hanger is then landed for supporting a string of production tubing that receives the hydrocarbons from the subsea well after the deepest string of casing is perforated.
Typically, the tubing hanger is lowered into the subsea wellhead assembly through a riser extending from a vessel at the surface. In previous systems, the tubing hanger had downward facing shoulders that would land on an upward facing support within the subsea housing. The downward facing shoulders typically increased the outer diameter of the tubing hanger, and thus also increased the minimum allowable diameter of the riser through which the tubing hanger was lowered. In other previous systems, the retractable locking assemblies were located on the outer periphery of the tubing hanger so that the outer diameter of the tubing hanger was smaller than previous tubing hangers. These locking assemblies were typically actuated mechanically when landing within the subsea wellhead housing by profiles formed in the subsea wellhead assembly that would engage and actuate the locking assembly radially outward to land upon the support surfaces in the subsea wellhead assembly. However, these assemblies required the tubing hanger to be oriented properly for such actuation to occur.
An assembly for landing a tubing hanger in a subsea well includes a riser extending from a subsea wellhead assembly to a vessel at the surface of the sea. A tubing hanger having a string of tubing suspended therefrom is lowered through the riser with a string of conduit, and the tubing hanger lands within the subsea wellhead assembly. A sensor is positioned adjacent the subsea wellhead assembly to monitor the axial position of the tubing hanger within the subsea wellhead assembly. The sensor also communicates the axial position of the tubing hanger to the surface. A locking mechanism is carried by the tubing hanger and is selectively operable to lock the tubing hanger in place relative to the subsea wellhead assembly when the tubing hanger reaches a predetermined axial location.
The sensor can have a receiver attached to an outer periphery of the riser. Alternatively, the sensor can also be carried by a remote operated vehicle.
In the assembly, the subsea wellhead assembly can also include a wellhead housing having a grooved profile formed in an inner bore thereof. The locking mechanism can also have a plurality of locking members or locking dogs positioned within an annular groove formed in the outer circumference of the tubing hanger. The locking members can have a lock profile that matingly engages the grooved profile when the locking members are actuated radially outward.
In the assembly, the locking mechanism can include an electrically-actuated solenoid in electrical communication with the vessel. The solenoid can have an extended position and a contracted position. The locking mechanism can also have a plurality of locking members that matingly engage an interior surface of the wellhead housing assembly when actuated radially outward by the solenoid when the solenoid moves to the extended position. The solenoid can be in the contracted position until the tubing hanger is lowered to the predetermined axial position, and the solenoid can be actuated to its extended position with an electrical current from the surface.
The assembly can also include a remote operated vehicle positioned adjacent the subsea wellhead assembly with an acoustical transmitter that selectively transmits an acoustical wave into the subsea wellhead assembly. Also in the assembly, the locking mechanism can have an accoustically-actuated solenoid that has an extended position and a contracted position. The locking mechanism can also have a plurality of locking members that matingly engage an interior surface of the wellhead housing assembly when actuated radially outward by the solenoid when the solenoid moves to the extended position. The solenoid can be in the contracted position until the tubing hanger is lowered to the predetermined axial position and the solenoid can be actuated to its extended position when the acoustic wave is transmitted into the subsea wellhead assembly.
The assembly can also include a controller on the vessel. The controller can have a power source and a modem. The controller having a first source terminal connecting to the string of conduit and a second source terminal connecting to the riser. The assembly can also include a conductor positioned on the outer surface of the string of tubing that can engage an interior surface of the subsea wellhead assembly to thereby define an electrical circuit for supplying power from the vessel to the sensor, the axial position transmitter, and the locking mechanism.
An assembly for landing a tubing hanger in a subsea well can also have a riser extending from a subsea wellhead assembly to a vessel at the surface of the sea. A tubing hanger with a string of tubing suspended therefrom is lowered through the riser with a string of conduit, and lands within the subsea wellhead assembly. An axial position transmitter is positioned adjacent the tubing hanger, and is in electrical communication with the vessel. The axial position transmitter transmits an axial position signal while being lowered through the riser and subsea wellhead assembly. A sensor is positioned adjacent the subsea wellhead assembly. The sensor receives the axial position signal and communicates the axial position of the axial position transmitter within the subsea wellhead assembly to the surface. A locking mechanism is carried by the tubing hanger, and is selectively operable to lock the tubing hanger in place relative to the subsea wellhead assembly when the axial position transmitter reaches a predetermined axial location.
The sensor can have a receiver attached to an outer periphery of the riser. Alternatively, the sensor can also be carried by a remote operated vehicle.
The assembly can also include a remote operated vehicle that is positioned adjacent the subsea wellhead assembly, and has an acoustical transmitter that selectively transmits an acoustical wave into the subsea wellhead assembly. In the assembly, the locking mechanism can also include an accoustically-actuated solenoid having an extended position and a contracted position. The locking mechanism can further include a plurality of locking members that can matingly engage an interior surface of the wellhead housing assembly when actuated radially outward by the solenoid when the solenoid moves to the extended position. The solenoid can be in the contracted position until the tubing hanger is lowered to the predetermined axial position, and the solenoid can be actuated to its extended position when the acoustic wave is transmitted into the subsea wellhead assembly.
The assembly can further include that the remote operated vehicle includes a stab and an electric coil housed within the stab. The electric coil can transmit a plurality of magnetic waves into the subsea wellhead housing. The sensor can receive reflections of the magnetic field waves responsive to the tubing hanger being lowered into the subsea wellhead assembly in order to determine the axial position of the tubing hanger. The assembly can further include that the tubing hanger can be connected to the string of conduit with a tubing hanger running tool having a smaller outer diameter than the tubing hanger. The sensor can receive a variation in the reflections of magnetic waves reflecting from the outer surface of the tubing than from the outer wall of the tubing hanger running tool, thereby signaling when the tubing hanger is in the predetermined axial position. Alternatively, the assembly can include that the axial position transmitter comprises a magnetized material. The sensor can receive a variation in the reflections of magnetic waves reflecting from the outer surface of the tubing than from the magnetized material of the axial position transmitter to signal when the tubing hanger is in the predetermined axial position.
In the assembly, the subsea wellhead assembly can include a wellhead housing having a grooved profile formed in an inner bore thereof. The locking mechanism can also include a plurality of inwardly-biased locking members positioned within an annular groove formed in the outer circumference of the tubing hanger. The locking members can have a lock profile that matingly engages the grooved profile when the locking members are actuated radially outward. The locking mechanism can also include a lock cam that is selectively movable between upper and lower positions. The lock cam can have an inclined surface that engages the locking members to actuate the locking members radially outward when the lock cam moves to the upper position. The assembly can further include that the locking mechanism also has an electrically-actuated solenoid in electrical communication with the vessel. The solenoid can be in contact with the lock cam to selectively move the lock cam between the upper and lower positions when the solenoid actuates between an extended position and a contracted position. The locking members can be actuated radially outward by the lock cam when the solenoid actuates to the extended position and moves the lock cam to its upper position. The solenoid can be in the contracted position until the tubing hanger is lowered to the predetermined axial position. The solenoid can be actuated to its extended position with an electrical current from the surface.
The assembly can also include a controller on the vessel. The controller can have a power source and a modern. The controller can have a first source terminal connecting to the string of conduit and a second source terminal connecting to the on the riser. The assembly can also have a conductor positioned on the outer surface of the string of tubing that engages an interior surface of the subsea wellhead assembly, which can thereby define an electrical circuit for supplying power from the vessel to the sensor and the locking mechanism.
The modem can receive signals from the sensor pertaining to the axial position of the tubing hanger within the subsea wellhead assembly. The modem can be used for communicating electric signals to the solenoid in order to actuate the solenoid when the tubing hanger is in the predetermined axial position.
A method of landing a tubing hanger in a subsea well includes the step of extending a riser from a subsea wellhead assembly to a vessel at the surface of the sea. A tubing hanger having a string of tubing suspended therefrom is then lowered with a string of conduit through the riser to within the subsea wellhead assembly. The axial position of the tubing hanger within the subsea wellhead assembly is monitored with a sensor positioned adjacent the subsea wellhead assembly. The axial position of the tubing hanger is communicated to the surface with the sensor. The tubing hanger is locked in place relative to the subsea wellhead assembly when the tubing hanger reaches a predetermined axial location, with a locking mechanism carried by the tubing hanger.
In the method, the locking of the tubing hanger step can be performed by actuating a solenoid to an extended position, which causes a plurality of inwardly-bias locking members to move radially outward and engage an interior surface of the subsea wellhead assembly.
In the method, lowering of the tubing hanger step can also include providing an axial position transmitter adjacent the tubing hanger and that is carried by the string of conduit. The lowering of the tubing hanger step can also include transmitting signals to the receiver with the axial position transmitter as the tubing hanger and the axial position transmitter are lowered through the riser and the subsea wellhead assembly.
Referring to
A riser 21 extends from shear rams 19 upward. Most drilling risers use flanged ends on the individual riser pipes that bolt together. Riser 21, on the other hand, preferably utilizes casing with threaded ends that are secured together, the casing being typically smaller in diameter than a conventional drilling riser. Riser 21 extends upward past sea level 23 to a blowout prevent (“BOP”) stack 25. BOP stack 25 is an assembly of pressure control equipment that will close on the outer diameter of a size range of tubular members as well as fully close when a tubular member is not located within. BOP stack 25 serves as the primary pressure control unit for the drilling and completion operation.
Riser 21 and BOP stack 25 are supported by a tensioner (not shown) of a floating vessel or platform 27. Platform 27 may be of a variety of types and will have a derrick and drawworks for drilling and completion operations.
In the preferred embodiment, a controller 39 is positioned on platform 27. Controller 39 is for controlling downhole activities, including landing tubing hanger 31, and sending and receiving signals from downhole sensors and transmitters. Controller 39 includes a modem 41 for sending and receiving the signals to the downhole sensors and transmitters, and a power supply 43 for transmitting power to downhole. Controller 39 is preferably positioned adjacent an upper portion of riser 21. A first source terminal 45 extends between controller 39 and conduit 37 so that controller 39 is in electrical communication with conduit 37. A second source terminal 47 extends between controller 39 and riser 21 so that controller 39 is in electrical communication with riser 21. In the preferred embodiment, second source terminal 47 acts as an electrical ground when there is a closed electrical circuit including conduit 37 and riser 21.
Referring to
Referring to
As best shown in
Referring to
A solenoid 67 is positioned within annular groove 59, between an upward facing ledge 69 of annular groove 59 and a lower surface of cam 61. Solenoid 67 is in electrical communication with controller 39, which electronically actuates solenoid 67 between a contracted position shown in
In operation, tubing hanger 31 with the string of production tubing 29 hanging therefrom is lowered into the bore of wellhead 11 and casing 52. Suspension dogs 55 are preferably radially inward, solenoid 61 being in the contracted position illustrated in
When axial position transmitter 49 reaches a predetermined depth location, which is typically within wellhead 11, modem 41 of controller 39 sends an electrical signal to actuate solenoid 67 from its contracted position (
Referring to
In one embodiment, receiver 51 senses and transmits signals pertaining to the axial position of axial position transmitter 49 as described above. In this embodiment however, solenoid 67 is an acoustically-actuated solenoid. When in the proper axial position for actuating suspension dogs 55, ROV 81 transmits an acoustical wave W1 into the wellhead assembly to actuated solenoid 67.
In another embodiment using ROV 81 shown in
The assembly and methods described herein allow an operator to utilize narrower drilling risers and BOP systems than typically used in the past. Previous assemblies included tubing hangers that could not fit through such narrow risers because of the width of the orientation devices used to mechanically align the tubing hanger within the bore of the wellhead housing, and because of the width of the locking members that engage the bore of the subsea wellhead housing. The assembly and methods described herein also does not require the tubing hanger to be aligned for automatically, mechanically actuating locking members upon landing. Rather, the locking members remain retracted radially inward until at the correct axial position for being actuated to engage the grooved profile of the bore of the wellhead housing.
The assembly described herein is configured to permit drilling and completion through a slim bore riser, typically comprising commercially available well casings, with a BOP positioned at or near the surface or subsea, while accommodating large bore completions.
While the invention has been shown in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but susceptible to various changes without departing from the scope of the invention. For example, the process and equipment used for landing production tubing 29 and tubing hanger 31 can easily be utilized for landing casing hangers and intermediate strings of casing.
This nonprovisional application claims the benefit and priority of provisional patent application U.S. Ser. No. 60/709,521, filed on Aug. 19, 2005, which is hereby incorporated by reference in its entirety.
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