Lower stack assembly of a blow-out preventer for a hydrocarbon extraction well and method thereof

Abstract

A lower stack assembly of a blowout preventer for a hydrocarbon extraction well includes a safety function that can be hydraulically activated to rapidly cut off a pipeline section. The assembly includes a first valve and a first fluidic connection connecting the first valve and the least one safety function, so that the first valve selectively cuts off a flow of fluid directed towards the safety function. The assembly further includes a port operatively connected to the first valve, cooperating with a remotely operated vehicle to transmit a pilot signal to the first valve, an accumulator housing pressurized fluid, and a second fluidic connection. By cooperating with the first valve, the accumulator supplies pressurized fluid to the safety function to activate it. The second fluidic connection connects the accumulator and the first valve, so that the second fluidic connection remains operative during the entire working life of the assembly.

Claims

1. A lower stack assembly of a blowout preventer for a hydrocarbon extraction well, the assembly comprising: at least one safety function that can be hydraulically activated to rapidly cut off of a pipeline section; at least one first valve; at least one first fluidic connection that connects in permanent manner said at least one first valve and said at least one safety function, so that said at least one first valve is adapted to selectively intercept a flow of fluid directed towards said at least one safety function; at least one port operatively connected to said at least one first valve, said at least one port being adapted to cooperate with a remotely operated vehicle to transmit a pilot signal to said at least one first valve; at least one accumulator, adapted to house pressurized fluid; and at least one second fluidic connection between said at least one accumulator and said at least one first valve, so that by cooperating with at least said at least one first valve said at least one accumulator is adapted to supply pressurized fluid, by said at least one second fluidic connection and said at least one first fluidic connection, to said at least one safety function in order to activate it, wherein said at least one second fluidic connection is formed by at least one rigid pipeline and connects in permanent manner said at least one accumulator and said at least one first valve, so that said at least one second fluidic connection remains operative during the entire working life of the assembly, wherein said at least one second fluidic connection remains operative also in case of detachment of a lower marine riser package associable with said lower stack assembly, wherein said at least one first fluidic connection comprises at least one second valve, wherein said at least one second valve is adapted to intercept a flow of fluid coming from said at least one accumulator and/or directed towards said at least one safety function, and wherein said at least one second valve is controlled by a second valve control device, and wherein said assembly further comprises at least one control panel comprising said at least one port and said second valve control device, so that said remotely operated vehicle is adapted to simultaneously cooperate both with said at least one port and with said second valve control device to control said first valve and said second valve, respectively, to activate said at least one safety function.

2. The lower stack assembly of claim 1, wherein said at least one second valve is a shut-off valve, and wherein said second valve control device is controlled independently from said at least one port.

3. The lower stack assembly of claim 1, wherein said at least one port is associated with a pilot valve, adapted to provide a pilot signal to said at least one first valve, wherein said pilot signal is a flow of fluid, wherein said pilot signal is a flow of fluid having a pressure lower than the pressure of the fluid housed in said at least one accumulator, wherein said lower stack assembly comprises a third fluidic connection branch that forms a permanent fluidic connection between said at least one port and said at least one first valve, wherein said at least one first valve is a pilot-operated valve, wherein said at least one first valve is a ball check valve or slide valve, and wherein said pilot signal is an electric signal.

4. The lower stack assembly of claim 1, wherein said second permanent fluidic connection comprises at least one pressure regulator which regulates the pressure of the fluid let out from said at least one accumulator, and said at least one pressure regulator decreases the pressure of the fluid let out from said at least one accumulator.

5. A blowout preventer for a hydrocarbon well, the blowout preventer comprising at least one lower stack assembly of claim 1.

6. The blowout preventer of claim 5, further comprising at least one lower marine riser package removably connected to said at least one lower stack assembly and, by a riser, to drilling means associated with said blowout preventer.

7. A method for activating a safety function for rapidly cutting off a pipeline section, the method comprising the steps of: providing a lower stack assembly of a blowout preventer for a hydrocarbon well according to claim 1; providing a remotely operated vehicle; associating said remotely operated vehicle with said at least one port; acting by said remotely operated vehicle on said second valve control device, whereby opening said second valve; transmitting a pilot signal to said at least one first valve, whereby activating said at least one safety function, thus avoiding to connect said at least one accumulator to said at least one first valve, said at least one second fluidic connection being permanently connected to said at least one accumulator and to said at least one first valve; and keeping said second fluidic connection operative during the entire working life of the lower stack assembly; and said step of transmitting a pilot signal to said first valve, whereby activating said at least one safety function, is also performed in absence of connection between said assembly and an associable lower riser marine package.

8. The method of claim 7, further comprising a step of acting by said remotely operated vehicle on said second valve control device whereby opening said second valve, said step being performed between the step of associating said remotely operated vehicle with said at least one port and the step of transmitting a pilot signal to said at least one first valve, whereby activating said at least one safety function.

9. A lower stack assembly of a blowout preventer for a hydrocarbon extraction well, the assembly comprising: at least one safety function configured to be hydraulically activated to rapidly cut off a pipeline section; at least one first valve; at least one first fluidic connection between said at least one first valve and said at least one safety function, so that said at least one first valve is adapted to selectively intercept a flow of fluid directed towards said at least one safety function; at least one port operatively connected to said at least one first valve, said at least one port configured to transmit a pilot signal to said at least one first valve; at least one accumulator, adapted to house pressurized fluid; and at least one second fluidic connection between said at least one accumulator and said at least one first valve, so that said at least one accumulator is adapted to supply pressurized fluid, by said at least one second fluidic connection and said at least one first fluidic connection, to said at least one safety function to activate it, wherein said at least one first fluidic connection comprises at least one second valve, wherein said at least one second valve is adapted to intercept a flow of fluid from said at least one accumulator and/or directed towards said at least one safety function, and wherein said at least one second valve is controlled by a second valve control device, and wherein said assembly further comprises at least one control panel comprising said at least one port and said second valve control device, so that a remotely operated vehicle positioned adjacent said control panel is configured to manipulate said at least one port and said second valve control device to activate said at least one safety function.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of BOP lower stack assembly, of the blowout preventer and of the method according to the invention will be apparent from the description provided below of preferred embodiments thereof, given by way of non-limiting examples, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a view (not in scale) which shows a blowout preventer according to an embodiment, in normal operating conditions and when connected to drilling means;

(3) FIG. 1b is a view (not in scale) which shows a blowout preventer in normal operating conditions, according to an embodiment of the invention;

(4) FIG. 2 diagrammatically shows the blowout of the content of the hydrocarbon extraction well from the blowout preventer, in faulty conditions, and a remotely operated vehicle;

(5) FIG. 3 shows an axonometric view of a blowout preventer, according to an embodiment, comprising a lower stack assembly and a lower riser marine package;

(6) FIG. 4 shows manipulator type of a remotely operated vehicle near the control panel, according to an embodiment of the invention;

(7) FIG. 5 diagrammatically shows a shear ram activation circuit, according to an embodiment of the invention;

(8) FIG. 6 shows a portion of a lower stack assembly, according to an embodiment;

(9) figures from 7 to 11 are diagrams which show the activation circuitry of at least one safety function, according to some embodiments.

DETAILED DESCRIPTION

(10) According to a general embodiment, a lower stack assembly 1 or lower stack 1 or BOP lower stack 1 of a blowout preventer 10 or BOP 10 for a hydrocarbon extraction well is provided.

(11) Said lower stack assembly 1 of a blowout preventer 10 is particularly adapted but not unequivocally intended for application in submerged, e.g. subsea environment, wherein said hydrocarbon extraction well is dug in the bed 25 of a body of water 26.

(12) Said lower stack assembly 1 comprises at least one safety function 2 which can be hydraulically activated to rapidly cut off a pipeline section. According to an embodiment, said safety function 2 comprises at least one shear ram, adapted to cut a pipeline section. According to an embodiment, said safety function 2 can be activated by pressurized fluid. According to an embodiment, said safety function 2 is housed in the cavity of an internally hollow body and comprises an abutment portion 27, adapted to receive a thrust action applied by the pressurized fluid like a piston housed in a cylinder, and a shearing portion 28, opposite to said abutment portion 27 and adapted to rapidly cut off a pipeline segment 21.

(13) Said lower stack assembly 1 comprises at least one first valve 3.

(14) According to an embodiment, said first valve 3 is a pilot-operated valve. According to an embodiment, said first valve 3 is a one-way valve. According to an embodiment, said first valve 3 is a ball check valve, preferably of the normally-closed type. According to an embodiment, said first valve 3 is a slide check valve, preferably of the normally-closed type.

(15) According to an embodiment, said first valve 3 is a valve adapted to intercept a fluid flow. According to an embodiment, said first valve 3 is a check valve.

(16) Said lower stack assembly 1 comprises at least one first fluidic connection 6 which connects in permanent manner said at least one first valve 3 and said at least one safety function 2, so that said at least one first valve 3 is adapted to selectively intercept a fluid flow directed towards said at least one safety function 2.

(17) According to an embodiment, said first fluidic connection 6 remains operational during the entire working life of the assembly 1. The expression “working life” does not also indicate maintenance interventions which may require the temporary detachment of the fluid connection.

(18) According to an embodiment, said first fluidic connection 6 is formed by at least one rigid wall pipeline.

(19) Said lower stack assembly 1 comprises at least one port 4 operatively connected to said at least one first valve 3, said at least one port 4 being adapted to cooperate with a remotely operated vehicle 5 to transmit a pilot signal to said at least one first valve 3. According to an embodiment, said remotely operated vehicle 5 is a remotely operated underwater vehicle 5 or ROV 5. According to an embodiment, said remotely operated vehicle 5 is operatively connected to a support vessel 23, e.g. by means of an umbilical cable 24 of the ROV for the supplying power and/or for exchanging information and/or controls.

(20) Said lower stack assembly 1 comprises at least one accumulator 7 adapted to house the pressurized fluid. According to an embodiment, said at least one accumulator 7 houses a sufficient volume of high-pressure fluid to actuate the rams of the BOP.

(21) Said lower stack assembly 1 comprises at least one second fluidic connection 8 between said at least one accumulator 7 and said first valve 3, so that said at least one accumulator 7 by cooperating with at least said first valve 3 is adapted to supply pressurized fluid, by means of said second fluidic connection 8 and said first fluidic connection 6, to said at least one safety function 2 to activate it.

(22) Advantageously, said at least one second fluidic connection 8 connects in permanent manner said at least one accumulator 7 and said at least one first valve 3, so that said second fluidic connection 8 remains operative during the entire working life of the assembly 1.

(23) By providing said at least one second fluidic connection 8 which connects in permanent manner said at least one accumulator 7 and said at least a first valve 3, a circuitry is provided which is already built and simply to be activated in emergency conditions. In other words, spending time in emergency conditions to construct a circuitry is avoided. In this manner, a secondary emergency system which can be readily activated can be made.

(24) According to an embodiment, said second fluidic connection 8 remains operational even in the event of detachment of a lower marine riser package 20 or LMRP 20 associable with said lower stack assembly 1. In this manner, a rapid activation of the secondary emergency system is allowed also in critical or catastrophic conditions.

(25) According to an embodiment, said second fluidic connection 8 is formed by at least one rigid pipeline 15. According to an embodiment, said second fluid connection 8 is formed by at least one rigid pipeline 15 at least partially made of steel for subsea pipelines suited to the conditions of use.

(26) According to an embodiment, said port 4 is associated with a pilot valve, adapted to provide a pilot signal to said first valve 3. In this manner, by cooperating with said port 4, said remotely operated vehicle 5 transmits said pilot signal to said first valve 3, whereby quickly activating it.

(27) According to an embodiment, said pilot signal is a fluid flow. According to an embodiment, said pilot fluid flow is supplied from said remotely operated vehicle 5.

(28) Preferably, said remotely operated vehicle 5 comprises at least one driving fluid reservoir which accommodates said driving fluid, and at least one working portion 17, or manipulator 17, which transmits said pilot signal, preferably said driving fluid flow to said port 4. According to an embodiment, said manipulator 17 is formed of a manipulator having a plurality of degrees of freedom. According to an embodiment, said manipulator 17 can manage a hot stab type connector which connects the driving reservoir and which transmits said pilot signal, preferably said driving fluid flow, to said port 4.

(29) According to an embodiment, said pilot signal is a pressurized fluid flow. According to an embodiment, said pilot signal is a fluid flow having lower pressure than the pressure of the fluid housed in said at least one accumulator 7. For example, the pressure of the fluid flow which forms the pilot signal is substantially equal to 20 MegaPascals (MPa), i.e. approximately equal to 3000 pound per square inch (psi). For example, the pressure of the fluid housed in said at least one accumulator 7 is substantially equal to 35 MegaPascal, i.e. approximately equal to 5000 psi.

(30) According to an embodiment, said assembly 1 comprises a third fluidic connection branch 22 which forms a permanent fluidic connection between said port 4 and said first valve 3.

(31) According to an embodiment, said first fluidic connection 6 is formed by at least one portion of a pipe. Preferably, said at least one pipe which forms said first fluid connection 6 has a diameter of about 2.54 cm, substantially equal to one inch.

(32) According to an embodiment, said second fluidic connection 8 is formed by at least one portion of a pipe. Preferably, said at least one pipe which forms said second fluid connection 8 has a diameter of about 2.54 cm, substantially equal to one inch. According to an embodiment, said assembly 1 comprises a plurality of accumulators 7 and said first fluid connection 8 branches into a plurality of accumulator branches, each accumulator branch being fluidically connected to at least one accumulator 7 of said plurality of accumulators.

(33) According to an embodiment, said third branch 22 is formed by at least one portion of at least one pipe. Preferably, said at least one pipe which forms said third fluid connection 22 has a diameter of about 0.64 cm, substantially equal to 0.25 inches.

(34) According to an embodiment, the at least one pipe which forms said third branch 22 has a diameter smaller than the diameter of at least one of the at least one pipe which forms said first fluid connection 6 and at least one pipe which forms said second fluidic connection 8.

(35) According to an embodiment, said pilot signal is an electric or electromagnetic signal. Preferably, said electric or electromagnetic pilot signal is supplied by said remotely operated vehicle 5. In this manner, a first valve can be operated quickly is provided.

(36) According to an embodiment, said first fluidic connection 6 comprises at least one second valve 9.

(37) According to an embodiment, said second valve 9 is adapted to intercept a flow of fluid coming from said at least one accumulator 7 and/or directed towards said at least one safety function 2. According to a preferred embodiment, said second valve 9 is an shut-off valve. Preferably, said first valve 9 is a ball shut-off valve.

(38) According to a preferred embodiment, said second valve 9 is an isolation valve. According to an embodiment, said second valve 9 is a shutter valve.

(39) According to an embodiment, said second valve 9 can be controlled by means of a second valve control device 11. According to an embodiment, said second valve control device 11 is a control lever, adapted to be handled by a ROV 5. According to an embodiment, said second valve control device 11 can be controlled independently by said port 4.

(40) According to an embodiment, said assembly 1 comprises at least one control panel 13 comprising said port 4 and said second valve control device 11, so that said remotely operated vehicle 5 is adapted to cooperate both with said port 4 and with said second valve control device 11 to activate said at least one safety function 2.

(41) According to an embodiment, said first fluidic connection 6 comprises at least one third valve 12. According to an embodiment, said third valve 12 is a selector valve. Providing said at least one third valve 12 makes it possible to selectively convey the fluid coming from said at least one accumulator 7 to the safety function 2.

(42) According to an embodiment, said assembly 1 comprises at least one emptying branch 35 comprising at least one fourth valve 34, or emptying valve 34, wherein said emptying branch 35 is arranged downstream of said safety function 2 and is adapted to allow an emptying fluid flow of said safety function. According to an embodiment, said at least one fourth valve 34 is a selector valve and, when open, it is adapted to allow emptying the process fluid from the safety function 2.

(43) According to an embodiment, said at least one emptying branch 35 is adapted to put into fluid communication said safety function 2 and said first valve 3, whereby returning the emptying fluid flow of the safety function 2 to said first valve 3. According to an embodiment, said at least one emptying branch 35 conveys the output fluid flow from said safety function 2 and, by means of said first valve 3, conveys it into said water body.

(44) According to an embodiment, said second fluidic connection 8 comprises at least one pressure regulator 14 which regulates the fluid pressure let out from said at least one accumulator 7. According to an embodiment, said at least one pressure regulator 14 decreases the fluid pressure let out from said at least one accumulator 7. By way of non-limiting example, the pressurized fluid stored in said at least one accumulator 7 has a pressure of 35 MegaPascal, substantially equal to 5000 psi and said pressure regulator 14 decreases the pressure let out from said at least one accumulator 7 to about 20 MegaPascals, which is substantially equal to 3000 psi.

(45) According to an embodiment, said second fluid connection 8 comprises at least one shut-off valve at the outlet of the accumulator 36, preferably interposed between said at least one accumulator 7 and said pressure regulator 14.

(46) According to an embodiment, said lower stack assembly 1 comprises a structural frame 29 which forms a supporting armature for the functional elements of the assembly 1. According to an embodiment, said structural frame 29 comprises at least one portion for connecting to the lower marine riser package 20, adapted to form a removable mechanical connection with said structural frame 29.

(47) According to an embodiment, said assembly 1, preferably said structural frame 29 of the assembly 1, comprises at least one wellhead connection element 16, adapted to put the contents of the hydrocarbon extraction well into fluid communication with a riser 19. For example, said wellhead connection element 16 is made by means of commercial connectors to the wellhead.

(48) According to an embodiment, said assembly 1, preferably said structural frame 29 of the assembly 1, delimits a housing for accommodating at least one pipeline section 21 which puts the contents of the hydrocarbon extraction well into fluid communication with a riser 19. Preferably, said structural frame 29 delimits a housing to accommodate a drilling rod 39 operatively connected to the drilling means 18. Preferably, said drilling rod 39 is associated with a casing 38.

(49) According to an embodiment, said drilling rod 39 is integral with said pipeline section 21. According to an embodiment, riser 19 is connected by one of its ends to drilling means 18, e.g. a drilling vessel 18 or a drilling platform. According to an embodiment, said riser 19 cooperates with said pipeline section 21 to put the contents of the hydrocarbon extraction well into fluid communication with the drilling means 18.

(50) According to an embodiment, said structural frame 29 is fitted on the said pipeline section 21.

(51) According to an embodiment, said at least one safety function 2 is adapted to cut off the fluidic communication between the contents of the hydrocarbon extraction well and said riser 19, preferably by cutting and/or tearing the casing 38 of said riser 19 and said pipeline section 21, and forming a barrier which prevents the spilling of the contents of the hydrocarbon extraction well 37. For example, a blowout of the content of the well 37 is diagrammatically shown in FIG. 2.

(52) According to an embodiment, said at least one safety function 2 is adapted to cut a portion of said pipeline section 21. Preferably, said safety function 2 comprises a cutting portion 28 comprising at least a cutting device for cutting a portion of said pipeline section 21.

(53) According to an embodiment, said assembly 1 comprises a plurality of safety functions 2. For example and in a known manner, said plurality of safety functions 2 comprises at least one shear ram, at least one blind shear ram or at least one pair of blind shear rams. Preferably, each ram consists of two opposite cutting elements which are operated by two distinct hydraulic circuits.

(54) According to an embodiment, the functions of said plurality of safety functions 2 can be operated in mutually independent manner. According to an embodiment, said assembly comprises a plurality of ports 4, so that each port 4 controls a safety function 2.

(55) According to an embodiment, the functions of said plurality of safety functions 2 can be activated simultaneously by the same port 4 and/or by the same control procedure.

(56) According to a general embodiment, a blowout preventer 10 for a hydrocarbon well comprises at least one lower stack assembly 1 according to any one of the embodiments described above.

(57) According to an embodiment, said blowout preventer 10 comprises at least one lower marine riser package 20 removably connected to said lower stack assembly 1 and, by means of a riser 19, to drilling means 18 associable with said blowout preventer 10.

(58) According to an embodiment, said lower stack package 20 comprises at least one primary pod, which is usually redundant with a secondary pod to increase system reliability. Preferably, such primary and secondary pods activate the valves and hydraulic branches according to the intervention logics set on the surface by the central control, and in particular, are adapted to receive control fluid to activate said at least one safety function 2 and adapted to cooperate with a control system, preferably located on said drilling means 18, adapted to send control signals to said pods to activate said safety functions 2, whereby forming a primary control system.

(59) According to an embodiment, said lower stack package 20 comprises at least one LMRP frame, adapted to form a removable mechanical connection with said structural frame 29 of said lower stack assembly 1.

(60) According to an embodiment, said lower stack package 20 comprises at least one pipeline end in fluid communication with said riser 19, preferably made in one piece with said riser 19, which connects in a removable manner to said pipeline section 21 which crosses said assembly 1.

(61) A method for activating a safety function 2 for rapidly cutting off a pipeline section 21 is described below.

(62) A method for activating a safety function 2 for rapidly cutting off a pipeline section comprises the following steps: providing a lower stack assembly 1 of a blowout preventer 10 for a hydrocarbon extraction well according to any one of the embodiments described above; providing a remotely operated vehicle 5; associating said remotely operated vehicle 5 with said port 4; transmitting a pilot signal to said first valve 3, whereby activating said at least one safety function 2.

(63) According to a possible mode of operation, the aforesaid steps are to be provided in succession in the indicated order.

(64) According to a possible mode of operation, said step of transmitting a pilot signal to said first valve 3, whereby activating said at least one safety function 2, is also performed in absence of connection between said assembly 1 and associable drilling means 18.

(65) According to a possible mode of operation, said step of transmitting a pilot signal to said first valve 3, whereby activating said at least one safety function 2, is also performed in absence of connection between said assembly 1 and an associable lower riser marine package 20.

(66) According to a possible mode of operation, said steps of associating said remotely operated vehicle 5 with said port 4 and transmitting a pilot signal to said first valve 3, whereby activating said at least one safety function 2, is performed by avoiding to build a circuitry.

(67) According to a possible mode of operation, said step of associating said remotely operated vehicle 5 with said port 4 comprises the sub-step of using an articulated arm and a manipulator 17 of said remotely operated vehicle 5 to said port 4 and transmitting a pilot signal to said first valve 3, whereby activating said at least one safety function 2.

(68) According to a possible mode of operation, said method comprises the further step of acting by means of said remotely operated vehicle 5 on said second valve control device 11, whereby opening said second valve 9. According to a possible mode of operation, this step is performed between the step of associating said remotely operated vehicle 5 with said port 4 and the step of transmitting a pilot signal to said first valve 3, whereby activating said at least one safety function 2.

(69) According to a possible mode of operation, said method comprises the following further step of adjusting the fluid pressure let out from said at least one accumulator 7.

(70) By virtue of the features described above, either mutually separately or jointly in particular embodiments, it is possible to obtain an assembly 1, a device 10 and a method which, at the same time, satisfy the aforesaid mutually contrasting needs and the aforesaid desired advantages, and in particular: it is reduced the risk related to the drilling operations in submerged environment; it is provided for a solution of lower stack 1 which is versatile and can be adapted to a wide range of LMRPs 20 present on the market; it is enabled a sharp reduction of the intervention time of the secondary emergency system; it is made possible to drive said first valve 3 with a low fluid flow rate, allowing it to be activated by the ROV 5 autonomously; it is made possible to make a permanent circuitry for the entire working life of the assembly 1 capable of activating the secondary emergency system in very timely manner, without because of this resulting in an excessively too bulky or poorly reliable circuitry; at the same time, it is avoided the need to construct the circuitry in emergency conditions, e.g. the need is avoided to connect an end of a flying lead when the lower stack 1 of the BOP 10 is not operatively or mechanically connected to the LMRP 20, e.g. due to bad weather and sea conditions or in conditions of absence of information on the location of the BOP 10 with respect to the drilling means 18; by proving said at least one third valve 12, preferably a selector valve, positioned along said first fluid connection 6, it is made possible to convey to the safety function 2 more circuitries adapted to activate the safety function 2, while makes it possible to enable them in selective manner; in this manner, by providing said at least one third valve 12, when said primary control system controls the activation of said safety function 2, said third valve is adapted to selectively intercept the flow of fluid coming from the accumulators 7; by providing said pressure regulator 14, pressurized fluid can be supplied having a pressure lower than the pressure at which the pressurized fluid is stored in the at least one accumulator 7, whereby avoiding damage to the circuitry components which require a process fluid at a pressure lower than the pressure of the fluid stored in the accumulators; providing an additional allows manual isolation valve present in said second fluid connection 8 makes it possible to isolate an accumulator or a group of accumulators in the event of malfunctioning; a high degree of modularity of the safety function activation circuitry is allowed; versatile assembly is provided, adapted to operate in different configurations, e.g. in dual-port configuration, in which a single port 4 manages the selective opening of two or more first valves which lead to respective safety functions, as well as single-port configuration, in which each port 4 manages the selective opening of a single valve and a single safety function; it is possible to avoid the spilling of the hydrocarbon extraction well contents even in conditions of where uncontrollable well blowout; the present invention provides an isolation system which prevents the uncontrolled spilling of product from a subsea hydrocarbon well; the present invention provides a system for rapidly activating the isolation system of a subsea well in situation of malfunctioning.

(71) A person skilled in art may make many changes, adaptations and replacements to the embodiments described above or may replace elements with others which are functionally equivalent in order to satisfy contingent needs without however departing from the scope of protection of the appended claims.

LIST OF REFERENCES

(72) 1. Lower stack assembly, or BOP lower stack, or lower stack 2. Emergency function or shear ram 3. First valve 4. Port 5. Remotely operated vehicle, or ROV 6. First fluidic connection 7. Accumulator 8. Second fluidic connection 9. Second valve 10. Blowout preventer, or BOP 11. Second valve control device 12. Third valve 13. Control panel 14. Pressure regulator 15. Rigid pipeline 16. Wellhead connection element 17. ROV manipulator, or operative portion of the ROV 18. Drilling means 19. Riser 20. Lower riser marine package, or LMRP 21. Pipeline section 22. Third fluidic connection branch 23. Support vessel 24. ROV umbilical cord 25. Seabed 26. Water body 27. Ram abutment portion 28. Ram cutting portion 29. Structural frame of the assembly 30. Primary pod 31. Secondary pod 32. LMRP frame 33. LMRP pipeline end 34. Fourth valve 35. Emptying branch 36. Shut-off valve at accumulator outlet 37. Spilling of petroleum product from well 38. Casing 39. Drilling rod