WO2022219554A1

WO2022219554A1 - Method and system for maintaining and drilling a well for the extraction of hydrocarbons

Info

Publication number: WO2022219554A1
Application number: PCT/IB2022/053470
Authority: WO
Inventors: Emanuele MOGNETTI; Romano BERGONZI; Luca IODICE; Emanuele CALÒ
Original assignee: Saipem SpA
Current assignee: Saipem SpA
Priority date: 2021-04-13
Filing date: 2022-04-13
Publication date: 2022-10-20
Anticipated expiration: 2023-10-13

Abstract

A method for maintaining and/or drilling a well (2) for the extraction of hydrocarbons from an underground hydrocarbon reservoir operated by a surface extraction site (4) has the steps of: transporting in a body of water (5) a maintenance/drilling module (7) and a feeding assembly (8) of the maintenance/drilling module (7) in the vicinity of the extraction site (4) by means of a transport vessel (9); transferring the maintenance/drilling module (7) from the transport vessel (9) to the extraction site (4); connecting the feeding assembly (8) to the maintenance/drilling module (7) by means of at least one pipeline (12); performing maintenance and/or drilling operations of said well (2) by means of the maintenance/drilling module (7); and keeping the feeding assembly (8) on board the transport vessel (9) during the maintenance and/or drilling operations of said well (2).

Description

"METHOD AND SYSTEM FOR MAINTAINING AND DRILLING A WELL FOR

THE EXTRACTION OF HYDROCARBONS"

Cross-Reference to Related Applications This patent application is related to Italian Patent

Application No. 102021000009266 filed on April 13, 2021, the entire disclosure of which is incorporated herein by reference .

Technical Field of the Invention The present invention relates to a method and system for maintaining and/or drilling a well for the extraction of hydrocarbons from an underground hydrocarbon reservoir.

State of the Art

As known, the extraction of hydrocarbons from a hydrocarbon reservoir located underground provides creating an extraction well through layers of rock until the hydrocarbon reservoir is reached.

During its operating life, due to deterioration of the well or changes in the chemical and physical characteristics of the reservoir, each extraction well requires maintenance operations so as to restore production and extend the operating life thereof.

In the oil & gas sector, the maintenance operations of an extraction well are named as "work-over" operations and provide carrying out a series of different activities depending on the state of the extraction well and on the conditions of the underground hydrocarbon reservoir.

Typically, these maintenance operations are performed by using a complex system comprising a maintenance/drilling module, which is arranged above the extraction well and is configured to perform invasive operations inside the well by introducing drill rods, pipes or other equipment into the extraction well. In addition, the system used comprises a feeding assembly, which is configured to feed process fluids into the extraction well through the maintenance/drilling module or to supply the maintenance/drilling module with water and fuel. In particular, the feeding assembly comprises infrastructure for the production and disposal of process fluids and containers configured to contain components for the production of process fluids.

Generally, the process fluid is a washing slurry, which is forced, by means of recirculation, to return to the surface, washing the extraction well and bringing debris from the extraction well to the surface.

In currently known maintenance/drilling systems, the feeding assembly is bulky and therefore requires a large area for storing it. In addition, a considerable amount of time is required to install the feeding assembly near the extraction well.

These drawbacks are even more significant when the extraction wells are located on artificial islands specifically created for the exploitation of a hydrocarbon reservoir, wherein the space available is limited and the cost of building each island is extremely high.

Subject and Summary of the Invention

The aim of the present invention is to provide a method for maintaining and/or drilling a well for the extraction of hydrocarbons that is free from the drawbacks of the prior art.

According to the present invention, a method is provided for maintaining and/or drilling a well for the extraction of hydrocarbons from an underground hydrocarbon reservoir operated by a surface extraction site, the method comprising the steps of:

- transporting in a body of water a maintenance/drilling module and a feeding assembly of the maintenance/drilling module in the vicinity of the extraction site by means of a transport vessel;

- transferring the maintenance/drilling module from the vessel to the extraction site; - connecting the feeding assembly to the maintenance/drilling module by means of piping;

- performing maintenance and/or drilling operations of said well by means of the maintenance/drilling module; and

- keeping the feeding assembly on board the transport vessel during the maintenance and/or drilling operations of said well.

Thanks to the present invention, for each maintenance or drilling operation, it is possible to save the time required for unloading the feeding assembly from the transport vessel and the time required for installing the feeding assembly in the area surrounding the well. Such an advantage is even more evident when it is necessary to perform maintenance in sequence on several wells belonging to a well field, as the system has to be frequently moved from one well to another.

By keeping the feeding assembly on board the transport vessel, it is also possible to clear the space in the area surrounding the extraction well and use fewer transport vessels. In case the well is obtained on an artificial island or on a platform specially constructed for extracting hydrocarbons from the subsoil, the present invention makes it possible to reduce the size of the island or platform and, consequently, to limit the costs of constructing the island or platform.

Time saved for installing the feeding assembly translates into a reduction in the well production downtime required to install it.

In addition, the system can be quickly transported to and employed in different extraction sites having different characteristics .

In particular, the method comprises the steps of transferring the maintenance/drilling module from the extraction site to the transport vessel once maintenance and/or drilling operations of said well are completed; and transporting the maintenance/drilling module and the feeding assembly to a further extraction site by means of the transport vessel.

Maintenance and/or drilling of a plurality of wells can thereby be performed quickly and cost-effectively. In addition, operations for dismantling and re-assembling the system are fast and help to reduce the time required to complete the entire activity compared to the systems of the prior art. In particular, the method comprises the steps of transporting in the body of water at least one service module for the staff in charge of maintenance and/or drilling operations by means of the transport vessel; and keeping the at least one service module on board the transport vessel during maintenance and/or drilling operations of said well.

It is thereby possible to save time required for unloading and installing the service modules and avoid cluttering up the area surrounding the well. These advantages are even more relevant when the extraction site is located in remote locations with particularly adverse climatic conditions .

In particular, the method comprises the step of feeding process fluids from the feeding assembly to the maintenance/drilling module in order to supply the maintenance/drilling module with process fluids to be injected into the well or to feed machinery.

In particular, the method comprises the steps of containing components of the process fluid in a plurality of containers disposed on board the transport vessel; and mixing said components on board the transport vessel so as to produce the process fluid.

It is thereby possible to store the components for the production of process fluids on the support vessel and to produce the process fluids, e.g. washing sludge, required for maintenance and/or drilling operations directly on the spot, on the transport vessel.

A further aim of the present invention is to provide a system for maintaining and/or drilling a well for the extraction of hydrocarbons from an underground hydrocarbon reservoir that is free from the drawbacks of the prior art.

According to the present invention, there is provided a system for maintaining and/or drilling a well for the extraction of hydrocarbons from an underground hydrocarbon reservoir operated by a surface extraction site, the system comprising:

- a maintenance/drilling module, which is configured to perform maintenance and/or drilling operations of said well; - a feeding assembly, which is configured to feed at least one process fluid to the maintenance/drilling module; and

- a transport vessel, which is configured to transport in a body of water the maintenance/drilling module and the feeding assembly in the vicinity of the extraction site and to keep the feeding assembly on board during maintenance and/or drilling operations of said well.

Thanks to the present invention, it is possible to quickly and cost-effectively perform maintenance and/or drilling operations on a well. Such advantages are even more evident when it is necessary to perform maintenance and/or drilling of a plurality of wells belonging to a well field.

Brief Description of the Drawings

Further characteristics and advantages of the present invention will become clear from the following description of a non-limiting embodiment thereof, with reference to the enclosed Figures, wherein:

- Figure 1 is a side elevation view, with parts removed for clarity and parts schematised, of a system for maintaining and/or drilling a well realised according the present invention and used in a hydrocarbon extraction site;

- Figure 2 is a side elevation view, with parts removed for clarity and enlarged, of the system of Figure 1; - Figure 3 is an elevation view, with parts removed for clarity, of the system of Figure 2; and

- Figure 4 is a side elevation view, with parts removed for clarity and parts schematised, of the system of Figure 1 in a further operating configuration and used in the hydrocarbon extraction site.

Detailed Description of Preferred Embodiments of the

Invention

Referring to Figure 1, number 1 denotes as a whole a system for maintaining and/or drilling a well 2 for the extraction of hydrocarbons from an underground hydrocarbon reservoir.

In the specific case herein described and shown, which is not limiting the present invention, the system 1 is employed in a well field 3 comprising a plurality of wells 2 located at surface extraction sites 4. In particular, surface extraction sites 4 are located on islands disposed in a body of water 5 which is characterised by a low depth (less than 10 metres). In more detail, the depth of the body of water 5 is such as to allow the creation of artificial islands in order to locate a respective surface extraction site 4 to exploit underground hydrocarbon reservoirs, which are not shown in the attached Figures. Each well 2 comprises a respective well head 6, which is disposed on the respective surface extraction site 4. The term "maintenance operations" refers to a series of operations performed on a well 2 to restore the original production and extend the operating life thereof. In the oil & gas sector, the maintenance operations of a well 2 are usually named as "work-over operations".

The maintenance operations of a well 2 provide to perform a plurality of different activities depending on the conditions of the well 2 and on the state of the underground hydrocarbon reservoir. Said maintenance operations comprise, for example, washing internally the well 2 using special sludge, which is delivered into the well 2 and is recirculated to bring accumulated debris to the surface, clearing the inside of the well 2. In addition, maintenance operations may comprise replacing or installing piping or additional equipment within well 2.

Although throughout this description, only the use of the system 1 in well maintenance applications 2 is described and shown, it must be understood that the system 1 may also be used for drilling wells 2. In particular, by way of example, following the creation of an artificial island in the body of water 5, the system 1 may be used to drill a well 2 on the artificial island by means of drill rods. In addition, the system 1 may be used to drill secondary wells from a previously realised original well 2.

The system 1 comprises a maintenance/drilling module 7, which is configured to perform maintenance and/or drilling operations of a well 2; a feeding assembly 8, which is configured to feed at least one process fluid to the maintenance/drilling module 7; and a transport vessel 9, which is configured to transport the maintenance/drilling module 7 and the feeding assembly 8 into the body of water 5 in the vicinity of the surface extraction site 4 and to keep the feeding assembly 8 on board during maintenance and/or drilling operations of the well 2.

The term "process fluid" refers to a fluid that is actively used within the well 2 in the maintenance and/or drilling operations.

For exemplary purposes, in interventions for internally washing the well 2, the process fluid used is a slurry consisting of fresh water and various additives, mainly of mineral origin. In case of an intervention for drilling a well 2, the process fluid substantially consists of water, which is delivered to digging members disposed at the lower ends of the drill rods to cool the digging members.

The maintenance/drilling module 7 is configured to be unloaded from the transport vessel 9, located on one of the extraction sites 4 above the respective well 2, and loaded onto the transport vessel 9 once the maintenance and/or drilling operations of the well 2 are completed.

In particular, the maintenance/drilling module 7 comprises a platform 10; a drilling tower 11 coupled to the platform 10; and equipment, not shown in the accompanying Figures, required to perform maintenance and/or drilling operations, including pumps, drill rods, manifolds and valve assemblies .

In addition, the system 1 includes a pipeline 12 configured to connect the feeding assembly 8 to the maintenance/drilling module 7.

In particular, the pipeline 12 is configured to be installed temporarily and preferably comprises flexible end portions.

The system 1 further comprises a service module 13 for the staff in charge of the maintenance and/or drilling operations, which is configured to be transported by the transport vessel 9 and to be kept on board the transport vessel 9 during the maintenance and/or drilling operations of the well 2.

In particular, the service module 13 comprises logistic facilities needed by the staff in charge of the maintenance/drilling operations of the wells 2. In more detail, the service module 13 comprises accommodation and catering facilities for the staff.

Referring to Figures 2 and 3, the feeding assembly 8 comprises infrastructure 14 for the production of process fluids, which are configured to be fed into one of the wells 2 in order to perform maintenance and/or drilling operations.

Furthermore, the feeding assembly 8 comprises a plurality of containers 15, each of which is configured to contain a respective component for producing said process fluids or fuel for feeding the maintenance/drilling module 7.

The infrastructure 14 comprises machinery, not shown in the accompanying Figures, for mixing the process fluid components and for feeding the process fluids to the maintenance/drilling module 7. According to a non-limiting embodiment of the present invention, the containers 15 are of the silo type and are preferably configured to contain water and/or cement and/or fuel and/or powdery materials used as additives in the washing sludge.

In the specific case herein described and shown, the transport vessel 9 is a shallow draft barge, configured to navigate in a body of water 5 of limited depth.

The transport vessel 9 comprises a deck 16 configured to house the maintenance/drilling module 6, the feeding assembly 8, the service module 13, and a plurality of power generators 17.

In addition, the transport vessel 9 comprises a handling device 18 configured to transfer the maintenance/drilling module 7 from the transport vessel 9 to the extraction site 4 and vice versa.

In particular, the handling device 18 comprises a carriage 19, which is provided with motorised and steerable wheels 20 and is configured to be transported by the transport vessel 9 and to be disposed underneath the maintenance/drilling module 7.

According to an embodiment herein described and shown, the handling device 18 is configured to support a plurality of support beams 21, which in turn support the weight of the maintenance/drilling module 7.

According to an alternative embodiment, not shown in the enclosed Figures, the transport vessel 9 comprises a gantry crane, which is configured to lift the maintenance/drilling module 7 and to transfer the maintenance/drilling module 7 from the transport vessel 9 to the extraction site 4 and vice versa.

In particular, the transport vessel 9 comprises an end 22 and an end 23. The feeding assembly 8 is disposed at the end 22, the service module 13 is disposed at the end 23, and the maintenance/drilling module 7 is configured to be disposed between the feeding assembly 8 and the service module 13. The load on the transport vessel 9 is thereby balanced in every operating configuration, even when, in use, the maintenance/drilling module 7 is unloaded from deck 16 of the transport vessel 9.

In use and referring to Figure 4, the maintenance/drilling module 7, the feeding assembly 8, and the service module 13 are transported on board the transport vessel 9, which sails in the body of water 5.

Referring to Figure 1, the transport vessel 9 is driven near one of the surface extraction sites 4 comprising the respective well 2 and the maintenance/drilling module 7 is transferred from the transport vessel 9 to the surface extraction site 4 via the handling device 18 so as to be disposed above the well 2.

As the maintenance/drilling module 7 is transferred, the components contained in the containers 15 are mixed on board the transport vessel 9 so as to produce the process fluids.

Subsequently, the feeding assembly 8 is connected to the maintenance/drilling module 7 via a pipeline 12 so as to feed the process fluids from the feeding assembly 8 to the maintenance/drilling module 7. At this point, the maintenance/drilling module 7 performs maintenance and/or drilling operations on the well

2.

During the maintenance and/or drilling operations the feeding assembly 8 and the service module 13 are kept on board the transport vessel 9. In other words, the feeding assembly 8 and the service module 13 are not transferred from the transport vessel 9 to the surface extraction site 4. Referring to Figure 4, once the maintenance and/or drilling operations on the well 2 are completed, the pipeline 12 is disconnected from the maintenance/drilling module 7 and the feeding assembly 8 and the maintenance/drilling module 7 is transferred from the surface extraction site 4 to the transport vessel 9 by means of the handling device 18.

Subsequently, the transport vessel 9 transports the maintenance/drilling module 7, the feeding assembly 8, and the service module 13 to a further surface extraction site 4 comprising a respective well 2 on which maintenance and/or drilling operations are to be performed.

Finally, it is clear that variations with respect to the embodiments described can be made to the present invention without however departing from the scope of protection of the attached claims.

Claims

1. A method for maintaining and/or drilling a well (2) for extracting hydrocarbons from an underground hydrocarbon reservoir operated by a surface extraction site (4), the method comprising the steps of: transporting in a body of water (5) a maintenance/drilling module (7) and a feeding assembly (8) of the maintenance/drilling module (7) in the vicinity of the extraction site (4) by means of a transport vessel (9); - transferring the maintenance/drilling module (7) from the transport vessel (9) to the extraction site (4); connecting the feeding assembly (8) to the maintenance/drilling module (7) by means of at least one pipeline (12); - performing maintenance and/or drilling operations of said well (2) by means of the maintenance/drilling module (7); and keeping the feeding assembly (8) on board the transport vessel (9) during the maintenance and/or drilling operations of said well (2).

2 . The method as claimed in Claim 1, and comprising the steps of transferring the maintenance/drilling module (7) from the extraction site (4) to the transport vessel (9) upon completion of the maintenance and/or drilling operations of said well (2); and transporting the maintenance/drilling module (7) and the feeding assembly (8) to a further extraction site (4) by means of the transport vessel (9).

3. The method as claimed in Claim 1 or 2, and comprising the steps of transporting in the body of water (5) at least one service module (13) for maintenance and/or drilling operators by means of the transport vessel (9); and keeping the at least one service module (13) on board the transport vessel (9) during the maintenance and/or drilling operations of said well (2).

4 . The method as claimed in any one of the foregoing Claims, and comprising the step of feeding process fluids from the feeding assembly (8) to the maintenance/drilling module (7).

5 . The method as claimed in Claim 4, and comprising the steps of containing components of the process fluid in a plurality of containers (15) disposed on board the transport vessel (9); and mixing said components on board the transport vessel (9) so as to produce the process fluid.

6. A system for maintaining and/or drilling a well (2) for the extraction of hydrocarbons from an underground hydrocarbon reservoir operated from a surface extraction site (4), the system (1) comprising: - a maintenance/drilling module (7), which is configured to perform maintenance and/or drilling operations of said well (2);

- a feeding assembly (8), which is configured to feed at least one process fluid to the maintenance/drilling module (7); and a transport vessel (9), which is configured to transport in a body of water (5) the maintenance/drilling module (7) and the feeding assembly (8) in the vicinity of the extraction site (4) and to keep the feeding assembly (8) on board during maintenance and/or drilling operations of said well (2).

7. The system as claimed in Claim 6, and comprising at least one pipeline (12) configured to connect the feeding assembly (8) to the maintenance/drilling module (7).

8. The system as claimed in Claim 6 or 7, and comprising a handling device (18), which is configured to transfer the maintenance/drilling module (7) from the transport vessel (9) to the extraction site (4).

9. The system as claimed in any one of Claims 6 to 8, and comprising at least one service module (13) for maintenance and/or drilling operators, which is configured to be transported by the transport vessel (9) and to be kept on board the transport vessel (9) during maintenance and/or drilling operations of said well (2).

10. The system as claimed in Claim 9, wherein the transport vessel (9) comprises a first end (22) and a second end (23); the feeding assembly (8) being disposed at the first end (22); the service module (13) being disposed at the second end (23); and the maintenance/drilling module (7) being configured to be disposed on board the transport vessel (9) between the feeding assembly (8) and the service module (13).

11. The system as claimed in any one of Claims 6 to 10, wherein the feeding assembly (8) comprises infrastructure (14) for the production of process fluids, which are configured to be fed into the well (2) in order to perform the maintenance and/or drilling operations.

12. The system as claimed in Claim 11, wherein the feeding assembly (8) comprises a plurality of containers (15), each of which is configured to contain a respective component for producing said process fluids or fuel for feeding the maintenance/drilling module (7).