WO2012149620A1

WO2012149620A1 - Connected, integrated underwater equipment with depressurisation systems

Info

Publication number: WO2012149620A1
Application number: PCT/BR2012/000122
Authority: WO
Inventors: Paula Luize Facre Rodrigues
Original assignee: Paula Luize Facre Rodrigues
Priority date: 2011-05-04
Filing date: 2012-05-02
Publication date: 2012-11-08
Also published as: BRPI1102236A2

Abstract

A layer comprising a wet Christmas tree (1) or connection module (26) or a set of underwater flow lines or a riser (27) are connected and integrated with resident depressurisation systems, which make petroleum production viable, significantly reduces production losses arising from blocking by hydrate. In the event of scheduled and non-scheduled production shutdowns, it is possible, as a preventive measure, to depressurise underwater lines and equipment in order to prevent hydrate formation or even to remove hydrates that have already formed. The operation can be performed remotely from a production unit (11) and does not require the use of a vessel or a probe. The invention can be used both in new-field projects and in mature fields.

Description

SUBMARINE EQUIPMENT CONNECTED AND INTEGRATED WITH

FIELD OF DEPRESSURIZATION FIELD OF INVENTION

The present invention belongs to the field of subsea systems and equipment, where a depressurization system is connected and integrated with subsea equipment for the purpose of preventing or removing hydrates; both in the equipment itself and in the subsea lines connected to them.

TECHNICAL STATE

Offshore oil production requires drilling of production and injection wells; and installation of equipment such as: Christmas tree, production manifolds (known as manifolds), liquid and gas separators, lifting systems, production lines between the wellhead and the production unit (UP). The UP can be located on a boat, on a fixed platform or on land.

For safety and control of subsea wells, equipment known as Wet Christmas Tree (ANM) is installed, where there is a set of valves to block the production column, another set of valves to block the annular space of the well; beyond the interconnections with the production lines, annular and umbilical through connection modules.

In the flow of deepwater underwater wells, produced liquids are in contact with gases under conditions of low temperatures and high pressures, and hydrate blockages may occur, both internally in the ANM and in the flow, production and annular lines.

To improve the reservoir recovery factor, several secondary oil recovery processes are employed, which require the injection of fluids in the form of gas or liquid, which may be water, natural gas, CO ² , etc. One such process is injection alternating gas and water, known as Water-alternating-gas - WAG, which in deep water presents a high risk of hydrate formation.

The variables that most influence hydrate formation and combat are: pressure and temperature. It is usually more practical to depressurize subsea lines and equipment than to try to increase their temperature. Several methods of depressurization have been developed and applied.

The first combat, when possible, is performed by depressurizing the annular line and opening the cross over valve, existing at ANM, to communicate the annular lines and production; and consequent depressurization of the production line.

A second possibility of combat is the depressurization of the production line from the end that is connected to the production unit. One of the techniques used is to lower a flexible tube, also known as coil tubing, into the nitrogen injection riser. Sometimes such a Production Unit does not have the resources or space to mount a flexible pipe unit and efficiently combat hydrate, or such a procedure is not sufficient; as the Production Unit is usually anchored in a water slide smaller than most wells, and there is still a hydrostatic column between the riser foot and the MNAs of each well.

Another possibility is to fight the hydrate from the end of the production line, which is directly connected to the producing well ANM, through a maritime completion probe. Due to the complexity of the operations, such work can last for days, greatly costing you. Although depressurization at both ends is desirable, it is common for operational limitations to perform depressurization at one end only.

US 4589434 published May 20, 1986, describes an apparatus and method for preventing hydrate formation in oil and gas pipelines. pipelines. It basically describes a depressurization apparatus based on a submarine liquid gas separator (11) with a concentric dual riser system where liquid is pumped by a pump (32) through the column (34) and gas flows through the annular space between the column (34) and the riser (30). The level of the separator (1) is controlled by the elements (44) and (40). Although that invention has been in the public domain for more than 5 years after the expiration of the 20-year patent term; The marketing or use by the applicant himself or by third parties of subsea oil production systems in any water slide is unknown. Such application has never been applied extensively, probably due to limitations and difficulties, especially in deep water, such as: subsea pumps have high cost and low reliability, need for a level control subsea gas and liquid separation system, construction difficulty of an underwater riser relief line, connected to the surface, with an internal tubular column for pumping liquid. In deep water the gas column back pressure will be high, forcing also high separation pressures, in throne of 20 Kg / cm ² , which may make the hydrate dissolution impossible. Add to the great difficulty of installing and replacing the pump (32), which will probably require a Probe. In addition to the economic technical unfeasibility of applying such apparatus extensively in subsea production systems, that is, one apparatus in each subsea equipment and line.

In US patent application US 2010/0047022 a hydrate removal system based on a coiled riser intervention vessel that connects to a point of the subsea system or directly to the top of an ANM has been described to create an open ring where at one end is the production unit and at the other side said vessel. Despite the merits of such an invention, considerable production losses continue to exist for several days until the boat is mobilized and connected to the seabed by said coiled riser. In addition, the process of pressure reduction, depressurization, utilizes nitrogen circulation; not using a bottom pump, which makes depressurization take longer and less efficient. Such a system is only mobilized after hydrate formation, being limited to promoting only remediation and not promoting any kind of prevention.

Generally the underwater wells are a few kilometers from the production unit; It is highly desirable to be able to perform hydrate prevention and removal operations immediately and remotely without the need for a rig or vessel; to reduce or eliminate production losses.

The currently used hydrate prevention techniques are: chemical injection to inhibit and use of thick thermal insulation in the production lines. Despite the merits, such techniques do not completely eliminate the occurrence of hydrates that are still responsible for considerable production losses.

The above described shortcomings of the state of the art are overcome in accordance with the present invention by the use of a pump-based depressurization system which can be easily connected and integrated with an underwater equipment or line, for example with a cover. Christmas Tree or Subsea Connection Module. An integrated, small diameter umbilical auxiliary line can receive the discharge from the depressurization pump, increasing the operating flexibility of the system without significantly increasing the construction and launching cost.

Also, an embodiment is proposed that allows depressurization at the end of the production line, which is connected to the Production Unit; through a depressurizer system connected to the riser's foot or alternatively by the descending into the riser a pump and inflatable packer by means of a cable known as a wireline.

Also provided is an embodiment for high flow wells, with or without liquid gas separator installed within the well, with equal diameter ring and production lines used to produce and enable inspection and cleaning pig passage.

The above limitations are solved by the use of a low-cost pump-based depressurization system, for example: a jet pump with no moving parts and high reliability, where all its drive is transferred to the surface of the production unit, facilitating its operation and maintenance. In addition, the removed fluid can be reinjected into the well or an existing line or returned to the UP by a small diameter auxiliary line that can be integrated into the same structure as the electro hydraulic umbilical or annular line. This makes it possible to take advantage of the production systems infrastructure, without increasing the construction and installation costs.

The proposed depressurization system, based on a small flow subsea pump, facilitates the prevention or removal of hydrates without the use of probes or vessels, while minimizing the use of chemical inhibitors. Due to the simplicity of the system and the low cost it is possible to distribute and connect a set of depressurization systems; equipment, lines and risers of subsea production systems; allowing hydrate prevention and removal to be performed for more than one point simultaneously and remotely from UP.

Although pumping systems already exist in the prior art, where pumps are installed on the sea floor or integrated with underwater Christmas trees, the purpose and functionality of the present invention is distinct and diverse. In the state of the art, high flow, high power subsea pumps are used simply to increase the flow rates produced. In the proposed application, the pumps for depressurization are turned off during production and are only activated in case of production shutdowns, preferably remotely from the Production Unit, to depressurize flow lines and subsea equipment, avoiding or removing hydrates. In this case, such pumps, eventually activated, require much lower powers than the mentioned production pumps.

In addition, although there has been deepwater oil production for over a decade, with hundreds of hydrate blockages occurring, they generate extremely high production losses; There is no low cost subsea equipment or hydrate prevention and removal system that works with the principle of immediate and remote depressurization from the UP, with multiple depressurization points, eg in trees, manifolds, risers. and other subsea equipment.

SUMMARY OF THE INVENTION

The present invention provides a hydrate prevention and removal depressurization system applicable to individual subsea wells or group of wells, producers or injectors, in offshore oil fields.

In deep water, usually each wet Christmas tree has: a production connection module, an annular connection module and an electro hydraulic umbilical anchoring module. Using multiplexed control, the number of umbilical hydraulic lines is reduced, making it easier to integrate the annular line with the umbilical in a single structure. It is also possible to add at least one extra small auxiliary line, for example: 1 ½ "; to function as a withdrawal fluid flow line or motive fluid line to drive a jet pump; or add a cable power to drive a multiphase electric pump for depressurization.

Such a pump, whether electrically or hydraulically powered, can be integrated with a variety of subsea equipment, including: an ANM cover, an underwater connection module, a UTU umbilical termination unit, a manifold, a riser to enable depressurization as a preventive or corrective measure of hydrate removal. The depressurization system can also be mounted to a cable and boat recoverable module to facilitate possible pump maintenance.

The pump installed in the ANM hood, according to the open or closed position of a valve assembly, selects which section will be suctioned and depressurized, for example: production column, production line or ring line. Also according to the position of pump discharge valves, the pumped fluid may be directed to different points, for example: production line, ring line, production column or return auxiliary line.

In the event of planned and unplanned production shutdowns, it is possible to depressurize sections of the flow lines and equipment, for example: ANM, in order to prevent the formation or removal of hydrates that may have formed.

The present invention has the following advantages:

- allows the prevention and removal of hydrate quickly and remotely from UP;

- reduces the risk of hydrate as it is possible to depressurize stopped lines;

- reduces the consumption of chemicals;

- facilitates start-up by inducing well emergence by reducing back pressure from production lines;

- minimizes downtime and production losses as the start of hydrate prevention or removal operations is almost immediate and does not require wait for the availability of critical and expensive resources such as vessels or probes.

- allows to clean and depressurize subsea equipment before removing them;

- can be applied for injector well cleaning operations through high flow reverse flow;

- is easily applied to manifold production systems without harming production;

- Easily connects and integrates with subsea equipment and lines, without burdening construction and installation costs.

The depressurizer can be embodied by various types of pumps, electrically or hydraulically driven; for example: a jet pump. Several substances may be used as the driving fluid with the addition of hydrate inhibiting substances.

In a first embodiment, at least one depressurizer is mounted integrated with the ANM hood or connection module or UTU, remaining resident during production, and remotely operated from the UP.

In a second embodiment, a depressurizer system is mounted at the foot of a riser, allowing remote depressurization from the UP side.

It is possible to combine the use of riser foot depressurizers with sub-marine depressurizers, for example: an ANM cover; to enable two-way depressurization, making operation faster and safer.

In the embodiment of depressurizer integrated with the connection module, it can be mounted integrated with the annular line connection module. Alternatively, the depressurizer can be integrated with the umbilical connection module. The present system comprises some embodiments, which will be further detailed in the various Figures accompanying the present application.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A schematically shows an ANM cap connected to a depressurizer system.

Figure 1B shows schematically a Connection Module with depressurizing system, embodied by electric pump.

Figure 1C schematically shows the section of an electro-hydraulic umbilical integrated with the annular line and power cable.

Figure 2A schematically shows an ANM cap with depressurizing system embodied by a hydraulically driven pump.

Figure 2B schematically shows a connection module with a depressurizing system, embodied by a hydraulically driven pump.

Figures 2C and 2D show sections of an umbilical integrated with the annular and motive fluid lines.

Figure 3A schematically shows an ANM cap with depressurizing system, embodied by a hydraulically driven pump with fluid return by an auxiliary line.

Figure 3B shows schematically an ANM cap with depressurizing system, embodied by electric pump with fluid return by an auxiliary line.

Figure 4 schematically shows a depressurization system resident in a UTU connected with an ANM.

Figure 5 schematically shows a depressurization system resident in a UTU connected to the riser foot.

Figure 6 shows UTU resident depressurization systems, one connected with an ANM and one connected to the riser foot. Figures 7A and 7B schematically show a pump descending inside a riser by means of a wireline.

Figure 8 shows schematically a pump depressurized system driven by a remote operating submarine vehicle known as ROV.

DETAILED DESCRIPTION OF THE INVENTION

For all Figures the following component reference list will be used:

I - cover with depressurizer system

2 - AN M of underwater well

3 - electric power cable

4 - electric pump

5 - hydraulically driven pump

6 - annular suction line

7 - production suction line

8 - Annular Discharge Line

9 - production discharge line

10 - check valve

I I - Production Unit, UP

12 - annular suction valve

13 - production suction valve

14 - annular discharge valve

15 - production discharge valve

16 - Driving Fluid Line

17 - connector

18 - electro hydraulic umbilical, known as umbilical control

19 - shutter, known as packer

20 - ROV driven pump

21 - ROV interface

22 - ROV 23 - Production Line

24 - ring line

25 - production column

26 - connection module

27 - riser

28 - flange

29 - block valve

30 - integrated umbilical, combines control lines with flowlines

31 - auxiliary line

32 - riser's foot

33 - riser shutoff valve

34 - cable, also known as wireline

35 - Umbilical Termination Unit known as UTU

36 - suction and depressurization line

M1 - production master valve

M2 - annular master valve

W1 - production wing valve

W2 - annular wing valve

S1 - production swab valve

S1 - annular swab valve

XO - Cross Over Valve

PXO - pig cross-over valve (shown in Figure 1 only)

DHSV - column safety valve

TPT - pressure and temperature transmitter

PT - pressure transmitter

PDG - Background Pressure Gauge

FM - volumetric flow meter

Figure 1A schematically shows an ANM cap (1) with a depressurizing system embodied by an electric pump (4) electrically powered by a power cable (3) from the UP. Valves (12) and (13) allow you to select a suction point, which can be on: production line (23), ring line (24) or production column (25). Valves (14) and (15) allow to select a discharge point, which can be on: production line (23), ring line (24) or production column (25). For a better understanding, the elements, valves, belonging to a conventional ANM are further illustrated: M1, M2, W1, W2, S1, S2, XO, PXO.

Figure 1B shows schematically a Connection Module (26) with depressurizing system, embodied by electric pump (10) that sucks the portion of the annular line (24) that is upstream of the block valve (29) and returns the fluid. for UP through the annular line section (24) downstream of the block valve (29). The flanges (28) are optional elements and are suitable for making the depressurizing system independent of the connection module (26). One of the flanges (28) can be suppressed if the depressurizer system is integrated with the connection module (26) in one piece.

Figure 1C schematically shows the section of an integrated umbilical (30) combining the ring line (24), the power cable (3) and the control lines in a single structure. In an alternative embodiment, not shown in the Figure, the ring line (24) would be conventional and the power cable (3) would be integrated with the umbilical (18) in a single structure.

Figure 2A schematically shows a pump-operated ANM cap (1) with a hydraulically driven pump (5) by a motive fluid line (16) from the UP. Similarly to Figure 1, valves (12) and (13) allow to select a suction point, which may be on: production line (23), ring line (24) or production column (25) and valves ( 14) and (15) allow you to select a discharge point, which can be on: production line (23), void line (24) or production column (25). To facilitate the In order to release and reduce the number of risers, the driving fluid line (16) can be integrated with the electro-hydraulic umbilical (18) or the annular line (24), see Figures 2C and 2D, respectively.

Figure 2B schematically shows a connection module (26) with a depressurizing system, embodied by a hydraulically driven pump (5), by the driving fluid line (16).

In Figure 2C, the driving fluid line (16) is integrated into the same structure as the electro hydraulic umbilical (18), forming an integrated umbilical (30). In Figure 2D the driving fluid line (16) is integrated into the same structure as the ring line (24).

Briefly, the driving fluid line (16) or power cable (3) used in Figures 1A, 1B, 2B, 2B can be integrated with: the electro hydraulic umbilical (18) into a single structure with the line to annul (24) independent; or even if the annular line (24) has a small diameter, for example: 2 ", it is possible to integrate the driving fluid line (16), the electro hydraulic umbilical (18) and the annular line (24), in a unique structure, called an integrated umbilical (30), facilitating the launch operation and reducing the number of UP risers.

Figure 3A schematically shows an ANM cover (1) with depressurizing system embodied by an electric pump (4) electrically powered by a power cable (3) from the UP. Valves (12) and (13) allow you to select a suction point, which can be on: production line (23), ring line (24) or production column (25). In this embodiment, the power cable (3) and auxiliary line (31) used for return of withdrawn fluid are integrated with the electro-hydraulic umbilical (24) into a single structure called integrated umbilical (30), see Figure 3B.

Figure 3B shows schematically a pump-operated ANM cap (1) with a hydraulically driven pump (5) by a driving fluid line (16) from the UP. Valves (12) and (13) allow you to select a suction point, which can be on: production line (23), ring line (24) or production column (25). In this embodiment, the driving fluid line (16) and the auxiliary line (31) used for fluid return are integrated with the electro hydraulic umbilical (24) into a single structure called an integrated umbilical (30), see Figure 3D.

Figure 4 schematically shows a depressurization system residing in a UTU (35) that depressurizes one or more points of an ANM (2) through a suction and depressurization line (36). A driving fluid line (16) and an auxiliary line (31) used for fluid return are integrated with an electro hydraulic umbilical (24) into a single structure called an integrated umbilical (30), similar to that shown in Figure 3D.

Figure 5 schematically shows a depressurization system resident in a UTU (35), similar to that of Fig. 4, but connected to the riser foot (32).

Figure 6 shows two UTU-resident depressurization systems (2), one connected with an ANM (2) and one connected to the riser foot (32).

The integration between the riser (27) and the depressurization pump (4) or (5) may be direct or by use of a plet type support base not shown in the Figure. In Plet-type structures, the depressurization system may also be integrated into the connection modules similar to those shown in Figures 1 B, 2B and 4.

Figure 7 schematically shows an electric pump (4) lowered into a riser (27) by means of a cable (34). A plug (19) is used to seal the suction and discharge of the electric pump (4). The pump sucks the riser portion (27) upstream of the pump itself (4) and discharges it to the riser riser portion (27) downstream of the pump itself (4). Figure 8 shows schematically a pump-implemented depressurizing system ANM cover (1) driven by a remotely operated submarine vehicle known as ROV (22). The ROV interface (21) transmits power, hydraulic or mechanical, to drive the pump (20). In this case the shut-off valves (12), (13), (14), (15) may be operated by ROV without the need of electric or hydraulic supply. This embodiment has application to existing fields where it is not desired to release new umbilicals and power cables; however, they rely on ROV and vessel resources.

The Subsea Flowmeter (FM), shown in the Figures, is an optional element that helps accompany the hydrate dissolution operation.

The shut-off valves shown in all Figures may be ROV-operated and may have either electric or hydraulic actuators to facilitate remote operation without relying on vessels.

Due to the simplicity and low cost of the proposed depressurization system, it is possible to distribute and connect multiple depressurization systems, distributed by the equipment, lines, manifolds and risers of subsea production systems; allowing the prevention and removal of hydrate can be performed for more than one point, simultaneously and remotely, from the PU (1 1). For example, it is possible to install a depressurizer on each ANM, one on each manifold and one on the foot of each riser.

While the present invention has been described with respect to its preferred embodiments, it is obvious to one skilled in the art that various changes and modifications are possible without departing from the scope of the present invention as determined by the appended claims.

Claims

1 - Christmas tree cover (1) coupled with a system for depressurizing flowlines and subsea equipment, characterized by:

- a pump, electric (4) or hydraulically driven (5), remotely operated from the UP or ROV (20), is coupled to a set of shut-off valves downstream and upstream of the pump (4) or ( 5) or (20), so that it is possible to suction and depressurize a fluid discharge ring line (24) to the production column (25) or to the production line (23) or to the auxiliary line (31 );

- changing the position of valves suction and depressurize the production line (23) with fluid discharge to the production column (25) or to the annulus line (24) or to the auxiliary line (31);

2 - Connection module (26) for interconnection of subsea lines and equipment, connected and integrated with a system for depressurizing flow lines and subsea equipment, characterized by:

- have a pump, electric (4) or hydraulically driven (5) or ROV driven (20); controlled and operated remotely from the UP; coupled to a set of block valves downstream and upstream of the pump (4) or (5) so that it is possible to suction and depressurize one side of the valve (29) by returning fluid to the other side of said valve (29) ) or by an auxiliary line (31).

- a connector (17) connects the connection module (26) to any subsea equipment;

3 - Depressurization system of flow lines and subsea equipment, installed at the riser foot (32), characterized by:

- a pump, electric (4) or hydraulically driven (5) or ROV-driven (20), operated remotely from the UP, is connected to a suction point at the riser foot (32) and its connected discharge, through an auxiliary line (31), to the riser itself (27) or directly with the UP (1 1).

- a riser shutoff valve (33) is used when the auxiliary line (31) is connected to the riser itself (27).

4 - Wet Christmas Tree (2) connected and integrated with a depressurization system, characterized by:

- the depressurization system, embodied by the pump (4) or (5) (20) and shutoff valves, may be integrated and located on the cover (1) or the connection module (26) or on the ANM itself (2) or in a UTU (35), interconnecting to the UP via an auxiliary line (31); in order to be able to suction and depressurize a fluid discharge ring line (24) to the production column (25) or to the production line (23) or to the auxiliary line (31); or by changing the position of valves suction and depressurize the fluid discharge production line (23) to the production column (25) or to the annular line (24) or to the auxiliary line (31) that connects to the UP (11);

- the auxiliary line (31) is used both to provide return of pump discharge fluid (4) or (5), as well as for access to the well ring.

5 - Umbilical Termination Unit with resident depressurization system, characterized by:

- be interconnected with an integrated umbilical having at least one motive fluid line (16) and one UP return line (31) connected to a pump (5);

- the suction of the pump (5) is interconnected via the suction and depressurization line (36) to at least one localized depressurization point of an underwater equipment or line, for example: an ANM (2), a manifold or foot of a riser (32).

Umbilical Termination Unit with resident depressurization system according to claim 5, characterized in that: - an electric pump (4) is used in place of the pump (5).

Underwater equipment and line depressurization system according to claim 1, 2, 3, 4 and 5; characterized by:

- an auxiliary line (31) returns the fluid moved by the pump

(4) or (5);

- a motive fluid line (16) drives the pump (5).

System for depressurization of equipment and subsea lines according to claim 1, 2, 3, 4 and 5; characterized by having:

- an integrated umbilical (30) constructed of at least one small diameter auxiliary line (16), for example: 1½ "; which is discharged from a pump (4) or (5) and flows to the UP ( 11).

9 - Depressurization system of: production line (23) or annular line (24) or ANM (2), characterized by:

- In a first alignment, for depressurizing the production line (23), the suction of the pump (4) or (5) is connected at a point downstream of the ANM valve S1 (2); and the discharge from pump (4) or (5) is connected downstream of valve S2:

- in a second alignment, for depressurization of the ring line (24), the suction of the pump (4) or (5) is connected at a point downstream of the ANM valve S2 (2); and the discharge from pump (4) or (5) is connected downstream of valve S1;

- a set of suction shut-off valves: (12) and (13), and at the discharge: (14) and (15), select which alignment of the depressurization operation will be, ie: first or second alignment;

System for depressurization of subsea equipment and lines according to claims 1, 2, 3, 4 and 5 characterized by: - a drive fluid line (16) which may be integrated with the electro-hydraulic umbilical (18) or annular line (24) carries a driving fluid to remotely drive a seabed (5) coupled hydraulic pump to an underwater equipment or line.

System for depressurization of equipment and subsea lines according to claims 1, 2, 3, 4 and 5; characterized by:

- an electric pump (4) is remotely driven by an electric power cable (3), which may be integrated with the electro hydraulic umbilical (18) or annular line (24);

System for depressurizing production lines (23) and annular (24) according to claims 1, 2, 3, 4 and 5, characterized in that:

- the suction of a pump (4) or (5) is interconnected to one or more points where depressurization is to be promoted;

- valves positioned upstream and downstream of the pump (4) or (5) provide selectivity of the points to be depressurized and the points to which the removed fluids will be directed.

System for depressurization of subsea equipment and lines according to claims 1, 2, 3, 4 and 5, characterized in that:

- All shutoff valves may have actuator, electric or hydraulic, to allow remote operation of them.

System for depressurization of subsea equipment and lines according to claims 1, 2, 3, 4 and 5; characterized by:

- a volumetric flow meter (FM) is installed, for example: at the pump suction (4) or (5) to monitor the evolution of hydrate dissolution. System for depressurizing production lines (23) and annular (24) according to claims 1, 2, 3, 4 and 5, characterized in that:

- be connected and integrated with a manifold type underwater equipment.

16 - Line connection base, known as PLET or PLEM, connected with a flow line and equipment depressurization system, characterized by:

- a pump (4) or (5) or (20) sucks a point at the riser foot (32) or at the base itself and returns the pumped fluid to the downstream section of the riser suction and shutoff valve (33) .

17 - Line connection base, known as PLET or PLEM, connected with a flow line and equipment depressurization system, characterized by:

- a pump (4) or (5) or (20) succeeds a point at the riser's foot

(32) or at the base itself and returns the pumped fluid to an auxiliary line (31) that is connected to UP.

18 - Depressurization system located on the inner side of the riser foot (32), lowered and installed inside a riser (27), characterized by:

- a pump (4) or (5), driven remotely from the UP, is lowered and fed by a cable (34).

- a plug (19) seals between the suction and discharge of the pump (4) or (5).

Depressurization system located at the foot of the riser interior (32) according to claim 18, characterized in that:

- In the cable structure (34) a heating system is installed and integrated: electric, resistive, capacitive or inductive; in order to heat the discharge fluid from the pump (4) or (5) and to prevent hydrate formation in the riser upstream (32). Depressurization system located within the riser foot (32) according to claim 18, characterized in that:

- In the cable structure (34) a hose for hydrate inhibitor fluid injection is installed and integrated in the pump discharge (4) or (5), preventing the formation of hydrate in the riser upstream (32).

21 - A depressurization system embodied by a pump (4) or (5), resident and integrated with any subsea equipment; controlled and operated remotely from a hydrate prevention and removal production facility applicable to individual submarine wells or group of wells and their respective flowlines in offshore oil fields.

22 - An integrated umbilical (30) constructed with at least one auxiliary line (31) and one driving fluid line (16) connected and integrated with subsea depressurization equipment and system.

23 - Hydrate prevention and removal method, characterized by:

- Depressurization of equipment and lines, by multiple points;

- The progress of depressurization is accompanied by the monitoring of flow meters (FM) and pressure indicators connected to subsea equipment and surface meters that record the pumped motive fluid flow rates and the returned fluid flow rate.