SYSTEM AND METHOD FOR HYDRATE PRODUCTION

Abstract

A system for hydrate production is configured to separate a water component from a multi-phase gas and water mixture present in a wellbore, the system being configured such that said separation occurs within the wellbore. The system comprises a first flow line disposed in the wellbore and arranged such that an inlet of the first flow line is disposed in and receives the water component, so as to separate the water component from said multi-phase gas and water mixture. A control system is configured to receive an output signal indicative of the water level from a sensor arrangement of the system and control a flow control device based on the water level so as to control the flow of the water component through the first flow line.

Claims

1. A system for hydrate production, wherein the system is configured to separate a water component from a multi-phase gas and water mixture present in a wellbore, the system being configured such that said separation occurs within the wellbore, wherein the system comprises: a first flow line disposed in the wellbore, the flow line arranged such that an inlet of the first flow line is disposed in and receives the water component of said multi-phase gas and water mixture, so as to separate the water component from said multi-phase gas and water mixture; a flow control device provided on or operatively associated with the first flow line; a sensor arrangement comprising one or more sensors configured to detect a water level of said water component in the wellbore and output an output signal indicative of said water level; and, a control system configured to receive the output signal indicative of said water level from the sensor arrangement and control the flow control device based on said water level so as to control the flow of the water component through the first flow line.

2. The system of claim 1 , wherein the flow control device comprises or takes the form of a variable flow control device.

3. The system of claim 1, wherein the flow control device comprises or takes the form of a choke.

4. The system of claim 1, comprising a pump coupled to or operatively associated with the first flow line, wherein the pump is configured to draw the water component of the multi-phase gas and water mixture present in the wellbore through the first flow line.

5. The system of claim 4, wherein the pump comprises or takes the form of one of: a single-phase pump; or, a multi-phase pump.

6. The system of claim 4, wherein the control system is configured to control the pump.

7. The system of claim 1, comprising a second flow line disposed in the wellbore, the second flow line arranged such that an inlet of the second flow line is disposed in and receives the gas component of said multi-phase gas and water mixture.

8. The system of claim 7, comprising a flow control device provided on or operatively associated with the second flow line.

9. The system of claim 8, wherein the flow control device comprises or takes the form of a variable flow control device.

10. The system of claim 8, wherein the flow control device comprises or takes the form of a choke.

11. The system of claim 1, wherein the sensor arrangement further comprises at least one of: one or more erosion sensors; one or more flow sensors; one or more position sensors of the flow control device provided on or operatively associated with the first flow line; and, one or more pressure and/or temperature sensors.

12. The system of claim 1, wherein the control system comprises a control module, wherein the control module is configured to: process sensor data received from the at least one of the sensors of the sensor arrangement; and at least one of: output one or more command signals to a position controller and/or actuation mechanism of the flow control device provided on or operatively associated with the first flow line, so as to control the position of said flow control device; and/or, output one or more command signals to a position controller and/or actuation mechanism of at least one isolation valve provided on or operatively associated with the first flow line, so as to control the position of said isolation valve.

13. The system of claim 1, wherein the control system comprises, is coupled to or communicates with a master control station or module.

14. The system of claim 13, wherein the master control station or module is configured to: process information from at least one topside system or module; and, output one or more command signals to a controller of the pump.

15. The system of claim 1, wherein the control system comprises, is coupled to or communicates with a pump control system.

16. The system of claim 1, wherein the system comprises or takes the form of a system for natural gas hydrate production, wherein the system is configured to separate a water component from a multi-phase natural gas and water mixture present in a wellbore.

17. The system of claim 1, wherein the system comprises or takes the form of a system for methane hydrate production, wherein the system is configured to separate a water component from a multi-phase methane gas and water mixture present in a wellbore.

18. A well system comprising the system for hydrate production according to claims 1.

19. The well system of claim 18, comprising a plurality of wellbores.

20. Use of the system for hydrate production according to any one of claims 1 or a well system having the system for hydrate production to separate a water component from a multi-phase gas and water mixture present in a wellbore, the system being configured such that said separation occurs within the wellbore.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0123] These and other aspects will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0124] FIG. 1 shows a diagrammatic view of a system for hydrate production;

[0125] FIG. 2 shows another diagrammatic view of the system shown in FIG. 1;

[0126] FIG. 3 shows a cap assembly of the system shown in FIG. 1;

[0127] FIG. 4 shows a manifold for the flow lines of the system shown in FIG. 1;

[0128] FIG. 5 is a diagrammatic view of the control system of the system shown in FIG. 1;

[0129] FIG. 6 shows an alternative system for hydrate production, comprising multiple wellbores;

[0130] FIG. 7 shows a logic diagram of how the system of FIG. 6 will operate; and

[0131] FIG. 8 shows a well system comprising the system for hydrate production shown in FIG. 6.

DETAILED DESCRIPTION OF THE DRAWINGS

[0132] Referring first to FIGS. 1 and 2 of the accompanying drawings, there is shown diagrammatic views of a system 10 for hydrate production. The illustrated system 10 is for methane hydrate production.

[0133] In use, and as will be described further below, the system 10 is configured to separate a water component W from a multi-phase methane gas and water mixture M present in a wellbore 12, the system 10 being configured such that the separation occurs within the wellbore 12.

[0134] As shown in FIG. 1, the system comprises a first flow line 14 disposed in the wellbore 12, the first flow line 14 arranged such that an inlet 16 of the first flow line 14 is disposed in and receives the water component W, so as to separate the water component W from the multi-phase methane gas and water mixture M.

[0135] In the illustrated system 10 shown in FIG. 1, the inlet 16 of the first flow line 14 forms the distal end of the first flow line 14.

[0136] However, it will be understood that the inlet may for example alternatively or additionally comprise one or more lateral flow ports in the first flow line 14. Also, while the system 10 comprises a single flow line 14, the system 10 may alternatively comprise a plurality of first flow lines 14.

[0137] As shown in FIG. 1, the system 10 further comprises a flow control device 18 provided on or operatively associated with the first flow line 14.

[0138] In the illustrated system 10, the flow control device 18 takes the form of a variable flow control device, more particularly a variable choke.

[0139] The system 10 further comprises a check valve 20. In the illustrated system 10, the check valve 20 comprises or takes the form of a ball valve.

[0140] The check valve 20 is provided on the first flow line 14 and is configured to prevent or limit back flow of the water component W through the first flow line 14, i.e. flow back towards the inlet 16. In the illustrated system 10, the check valve 20 is interposed between the inlet 16 of the first flow line 14 and the flow control device 18.

[0141] The system 10 further comprises a sensor arrangement comprising sensors 22, 24 configured to detect a water level of the water component W in the wellbore 12 and output an output signal indicative of the water level.

[0142] In the illustrated system 10, the sensors 22, 24 each take the form of a downhole pressure and temperature (DHPT) gauge. The sensor 22 measures the pressure and/or temperature at a first wellbore location. The sensor 24 measures the pressure and/or temperature at a second wellbore location. Since the distance between the sensors 22, 24 is known, the water level can readily be determined. However, it will be understood that other suitable sensors for measuring the water level may be employed.

[0143] As shown in FIG. 1, the system 10 comprises a pump 26 coupled to or operatively associated with the first flow line 14.

[0144] The pump 26 is configured to draw the water component W from the wellbore 12 through the first flow line 14.

[0145] In the illustrated system 10, the pump 26 comprises or takes the form of a single-phase centrifugal pump, i.e. a pump configured to handle a single-phase fluid.

[0146] Beneficially, the system 10 is configured to separate the water component W of the multi-phase water and methane gas mixture M within the wellbore 12, and so can utilise a single-phase pump such as the pump 26 which offers greater control over the fluid flow through the first flow line 14.

[0147] As shown in FIG. 1, the system 10 comprises a second flow line 28. The second flow line 28 is disposed in the wellbore 12 and is arranged such that an inlet 30 of the second flow line 28 is disposed in and receives the methane gas component G of the multi-phase methane gas and water mixture M.

[0148] In the illustrated system 10, the inlet 30 of the second flow line 28 forms the distal end of the second flow line 28.

[0149] However, it will be understood that the inlet 30 may for example alternatively or additionally comprise one or more lateral flow ports in the second flow line 28. Also, while the system 10 comprises a single flow line 28, the system 10 may alternatively comprise a plurality of second flow lines 28.

[0150] As shown in FIG. 1, the system 10 comprises a flow control device 32 provided on or operatively associated with the second flow line 28. In the illustrated system 10, the flow control device 32 takes the form of a variable flow control device, more particularly a variable choke.

[0151] The system 10 further comprises an isolation valve 34 provided on or operatively associated with the second flow line 28. In the illustrated system 10, the isolation valve 34 takes the form of an annulus isolation valve.

[0152] As shown in FIG. 1, and referring now also to FIGS. 2 and 3 of the accompanying drawings, the system 10 further comprise a cap 36. The cap 36 is coupled to and/or mounted on a wellhead 38 (shown in FIG. 2) and as shown in FIG. 2 it can be seen that that in the illustrated system 10 the first and second flow lines 14, 28 are disposed through the wellhead 38.

[0153] As shown in FIG. 2, the system 10 further comprises a tubing hanger 40. The tubing hanger 40 is disposed on and/or supported by the wellhead 38. The first and second flow lines 14, 28 are disposed through the tubing hanger 40.

[0154] As shown in FIG. 3 of the accompanying drawings, the system 10 comprises a flow meter 42, which in the illustrated system 10 takes the form of a single-phase flow meter.

[0155] As shown in FIGS. 2 and 3, the system 10 further comprises a valve 44 suitable for opening and closing the first flow line 14, which in the illustrated system 10 takes the form of a ROV-operable gate valve.

[0156] As shown in FIG. 4 of the accompanying drawings, the system 10 further comprises a manifold 48. As shown in FIG. 4, first flow lines 14 feed into a water production header 47 and second flow lines 28 feed into a gas production header 49.

[0157] Referring now to FIG. 5 of the accompanying drawings, there is shown a diagrammatic view of a control system 50 of the system 10 shown in FIG. 1.

[0158] The control system 50 is configured to receive the output signal indicative of said water level from the sensor arrangement and control the flow control device 18 based on the water level so as to control the flow of the water component W through the first flow line 14. In the illustrated system 10, the control system 50 forms or forms part of a subsea well control system.

[0159] As shown in FIG. 5, the control system 50 comprises a control module 52, which in the illustrated control system 50 takes the form of subsea control module.

[0160] The subsea control module 52 is configured to process sensor data received from at least one of the sensors of the sensor arrangement (and/or any other inputs to the subsea control module 52) and output one or more command signal to a position controller 60 of the choke 18 to control the position of the choke 18 and to a position controller 62 of the isolation valve(s) 46 to control the position of the isolation valve(s) 46. In the illustrated system 10, the subsea control module 52 is configured to process sensor data received from the one more water level sensors 22, 24; one or more erosion sensors 54; one or more flow sensors (such as flow meter 42), one or more choke position sensor 56; one or more pressure and/or temperature sensors 58.

[0161] As shown in FIG. 5, the control system 50 comprises a master control station or module 64. The control module 52 is configured to communicate with the master control station or module 64 and vice-versa.

[0162] The master control station or module 64 is configured to receive information from one or more topside systems or modules. In the illustrated system 10, the master control station or module 64 is configured to receive information from an emergency shut down (ESD) system or module 66 and a system flow demand system or module 68. However, it will be understood that the master control station or module 64 may receive one or more inputs from a variety of other sources in addition to or as an alternative to an emergency shut down (ESD) system or module 66 and a system flow demand system or module 68.

[0163] The master control station or module 64 is configured to process the information from the one or more topside modules, e.g. the emergency shut down module 66 and the system flow demand module 68 (and/or any other inputs to the master control station or module 64) and output one or more command signal to a controller 70, in particular speed controller, of the pump 28 (shown in FIG. 1).

[0164] The control system 50 comprises, is coupled to or communicates with a pump control system 72, which in the illustrated system 10 takes the form of a subsea pump control system.

[0165] The pump control system 72 comprises a pump control module. The pump control system 72 comprises or takes the form of a processor.

[0166] The pump control module 74 communicates with one or more sensors associated with control of the pump and one or more actuators associated with control of the pump, collectively represented as reference 76 in FIG. 6.

[0167] The system 10 provides a number of significant benefits over conventional equipment and methodologies.

[0168] For example, the system 10 utilises the methane hydrate production wellbore 12 itself to separate the water component W from the gas, thereby eliminating or at least reducing the need for further separation of the phases downstream of the wellbore 12

[0169] Moreover, conventional equipment and methodologies involve transporting a multi-phase mixture to the surface which as described above can re-form into a hydrate at the pressure and temperature conditions typically found at the seabed. By contrast, in the present system separation occurs within the wellbore, such that the risk of hydrate re-formation is eliminated or at least significantly reduced. This in turn improves the availability and/or efficiency of the methane hydrate production system as well as reducing downtime associated with workover operations and the like and/or reducing or eliminating the need to use chemical hydrate inhibitors, heating equipment or other hydrate mitigations.

[0170] The provision of a system in which separation occurs in the wellbore eliminates or at least mitigates the problems of slugging and wear in production equipment such as pipework, pumps, separators which otherwise may result from excessive water and/or sand production, since greater control can be achieved when handling single-phase fluid flows compared to the current multi-phase fluid flows. Moreover, whereas conventional systems require equipment capable of handling multi-phase fluids the present system can utilise equipment designed for handling single-phase fluids. In addition to being simpler and generally less costly to implement, such single-phase equipment provides a greater degree of control of the liquid flowrate at the well, reducing the risk of wellbore collapse.

[0171] Moreover, methane hydrates are sensitive to high flow rates and thus the present system beneficially facilitates the flow rate to be controlled using the flow control device on the first flow line.

[0172] It will be understood that various modifications can be made without departing from the scope of the invention as defined in the claims.

[0173] For example, FIG. 6 shows an alternative system 110 for methane hydrate production, comprising multiple wellbores 112a,b. The illustrated system 110 shows two wellbores 112a,b. However, it will be understood the system 110 may comprise any number of wellbores 112a,b, #.

[0174] As shown in FIG. 6, the system 110 comprises two flow lines 114a,b disposed in respective wellbores 112a,b, the flow lines 114a,b arranged such that inlets 116a,b of the flow line 114a,b is disposed in and receives the water component Wa,b so as to separate the water component Wa,b from the multi-phase methane gas and water mixture Ma,b.

[0175] In the illustrated system 110 shown in FIG. 6, the inlets 116a,b form the distal end of the first flow line 114a,b.

[0176] However, it will be understood that the inlets 116a,b may for example alternatively or additionally comprise one or more lateral flow ports in the flow lines 114a,b. Also, while the system 110 comprises a single flow line 114a,b per wellbore 112a,b, the system 110 may alternatively comprise a plurality of flow lines 114a,b per wellbore 112a,b.

[0177] As shown in FIG. 6, the system 110 further comprises flow control devices 118a,b provided on or operatively associated with the flow lines 114a,b.

[0178] In the illustrated system 10, the flow control devices 118 takes the form of a variable flow control device, more particularly variable chokes.

[0179] The system 110 further comprises check valves 120a,b. In the illustrated system 110, the check valves 120a,b comprise or takes the form of ball valves.

[0180] The check valves 120a,b are provided on the flow lines 114a,b and are configured to prevent or limit back flow of the water component Wa, Wb through the respective flow lines 114a,b. In the illustrated system 110, the check valves 120a,b are interposed between the inlets 116a,b of the first flow lines 114a,b and the flow control devices 118a,b.

[0181] The system 110 further comprises a sensor arrangement comprising sensors 122a,b, 124a,b configured to detect a water level of the water components Wa,b in the wellbores 112a,b and output an output signal indicative of the water level.

[0182] In the illustrated system 110, the sensors 122a,b, 124a,b each take the form of a downhole pressure and temperature (DHPT) gauge. The sensor 122a,b measure the pressure and/or temperature at respective first wellbore locations in the wellbores 112a,b. The sensors 124a,b measure the pressure and/or temperature at respective second wellbore locations in the wellbores 112a,b. Since the distance between the sensors 122a,b is known and the distance between the sensors 1224,b is known, the water levels can readily be determined. However, it will be understood that other suitable sensors for measuring the water level may be employed.

[0183] As shown in FIG. 6, the system 110 comprises a pump 126 coupled to or operatively associated with the flow lines 114a,b.

[0184] The pump 126 is configured to draw the water components Wa,b from the wellbores 112a,b through the flow lines 114a,b.

[0185] In the illustrated system 110, the pump 26 comprises or takes the form of a single-phase vertical centrifugal pump, i.e. a pump configured to handle a single-phase fluid.

[0186] Beneficially, the system 110 is configured to separate the water components Wa,b of the multi-phase water and methane gas mixture Ma,b within the wellbores 112a,b, and so can utilise a single-phase pump such as the pump 126 which offers greater control over the fluid flow through the flow lines 114a,b.

[0187] As shown in FIG. 6, the system 110 comprises a flow lines 128a,b. The flow lines 128a,b are disposed in the wellbores 112a,b and are arranged such that inlets 130a,b of the flow lines 128a,b are disposed in and receive the methane gas component Ga,b of the multi-phase methane gas and water mixture Ma,b.

[0188] In the illustrated system 110, the inlets 130a,b of the flow lines 128a,b form the distal end of the second flow lines 128a,b.

[0189] However, it will be understood that the inlets 130a,b may for example alternatively or additionally comprise one or more lateral flow ports in the flow lines 128a,b. Also, while the system 110 comprises a single flow line 128a,b per wellbore 112a,b, the system 110 may alternatively comprise a plurality of flow lines 128a,b per wellbore 112a,b.

[0190] As shown in FIG. 6, the system 10 comprises flow control devices 132a,bprovided on or operatively associated with the flow lines 128a,b.

[0191] In the illustrated system 10, the flow control devices 132a,b take the form of variable flow control devices, more particularly variable chokes.

[0192] The system 110 further comprises isolation valves 134a,b provided on or operatively associated with the flow line 128a,b.

[0193] FIG. 7 shows an example logic diagram of how the system of FIG. 6 may operate. As described above, while the system 110 comprises two wellbores 112a,b the system 110 may comprise any number of wellbores. The additional wellbores is/are represented in FIG. 7 by #.

[0194] FIG. 8 shows a well system 1000 comprising the system 110 for methane hydrate production shown in FIG. 6 coupled to a vessel V via a riser R.

[0195] This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application.