Systems and methods for hydrate production

Abstract

A system (10) for hydrate production is configured to separate a water component (W) from a multiphase mixture of gas and water (M) present in a wellbore (12), the system (10) being configured to cause the separation to occur within the wellbore (12). The system (10) includes a first flowline (14) disposed within the wellbore (12) and an inlet (16) of the first flowline (14) disposed in and arranged to receive the water component (W) for separating the water component (W) from the multiphase mixture of gas and water. A control system (50) is configured to receive an output signal indicative of a water level from a sensor arrangement of the system (10) and to control a flow control device (18) to control a flow rate of the water component (W) through the first flowline (14) based on the water level.

Description

Technical Field

[0001] The present invention relates to a system and method for hydrate production, such as methane hydrate production.

Background Art

[0002] Methane hydrate is an ice-like solid containing methane gas and water in an ice phase. Methane hydrate layers are known to contain significant amounts of methane and are an important source of natural gas.

[0003] Methane hydrate production involves drilling a wellbore (a "well hole") from the surface, which is then lined with a section of a metal bore lining pipe commonly known as casing. Following completion of the well hole, production fluids (including, in the case of methane production, methane gas, water, and entrained solids such as sand) can enter the well hole and are then transported to the surface.

[0004] To control production from a given well hole, a flow control configuration including a valve arrangement known as a tree is typically placed at the wellhead. The valve arrangement includes several flow control valves and safety valves configured to control the flow rate of the production fluids and / or to facilitate well isolation. The valve arrangement also controls access into the well for tools, equipment, and fluids.

Summary of the Invention

Problems to be Solved by the Invention

[0005] There are several important problems associated with methane hydrate production.

[0006] For example, the extraction of methane hydrate requires local depressurization of the methane hydrate layer. If the production rate is too high, excessive water and sand can occur suddenly in many cases. This causes problems of slugging and wear in the piping, pumps, separators, and other production facilities downstream of the production well. Further, careful control and monitoring of the flow rate and well pressure are necessary to ensure that the flow rate is not so high as to collapse the well.

[0007] Methane hydrate is easily reformed at the ambient pressure and temperature found at typical water depths in a subsea well system. When the pressure and temperature return to the hydrate formation pressure and temperature, for example due to some flow turbulence, solid methane hydrate is reformed within the production facilities. Chemical substances and / or heating systems have been proposed to prevent the formation of methane hydrate, but the use of such chemical substances and systems represents a significant cost to the operator, to the extent that the well may become uneconomical.

[0008] Designing a large-scale full-field system for simultaneously drawing down multiple wells requires ensuring that the separator operates in laminar flow as much as possible. Small systems with high fluid velocities have turbulent flow and draw in water along with the gas. Maintaining a low fluid velocity requires either a very large-capacity separator or multiple separators, resulting in added complexity and cost.

[0009] Designing a system to accommodate a wide range of gas-to-water ratios from multiple wells and continue to produce them at optimal flow rates is particularly difficult.

[0010] According to a first aspect, a system for hydrate production is provided, the system being configured to separate a water component from a multiphase mixture of gas and water present in a wellbore, the system being configured such that the separation is performed within the wellbore, the system A first flow line disposed within a wellbore hole, wherein the flow line is arranged such that an inlet of the first flow line is disposed within a water component of a multiphase mixture of the gas and water to receive the water component, for separating the water component from the multiphase mixture of the gas and water, the first flow line; A flow control device provided on the first flow line or operably associated with the first flow line; A sensor configuration including one or more sensors configured to detect a water level of the water component within the wellbore hole and output an output signal indicative of the water level; A control system configured to receive an output signal indicative of the water level from the sensor configuration and control the flow control device based on the water level to control a flow rate of the water component passing through the first flow line.

[0011] This system provides several important advantages over conventional equipment and methodologies.

[0012] For example, the system utilizes the hydrate production wellbore hole itself to separate the liquid component (particularly water) from the gas and solids, thereby eliminating or at least reducing the need for further separation of the phases downstream of the wellbore hole (or multiple wellbore holes in the case of a wellbore system comprising multiple wellbore holes).

[0013] Furthermore, conventional equipment and methodologies involve transporting a multiphase mixture that can reform into hydrates at the pressure and temperature conditions typically found in the ocean to the surface, as described above. In contrast, in this system, the separation occurs within the wellbore hole, thus eliminating or at least significantly reducing the risk of hydrate reformation. This improves the availability and / or efficiency of the hydrate production system, reduces the downtime associated with repair work, etc., and / or reduces or eliminates the need to use chemical hydrate inhibitors, heating equipment, or other hydrate mitigation agents.

[0014] Providing a system in which separation occurs within the wellbore can achieve greater control when handling single-phase flow compared to current multiphase flow rates, thereby eliminating or at least reducing slugging and wear problems in production equipment such as piping, pumps, and separators that can otherwise result from excessive water and / or sand production. Further, while conventional systems require equipment capable of handling multiphase fluids, the present system can utilize equipment designed to handle single-phase fluids. Such single-phase equipment is simpler to implement and generally less expensive, and in addition provides a higher degree of control of liquid flow rates in the wellbore, reducing the risk of wellbore collapse.

[0015] Furthermore, hydrate wells are sensitive to high flow rates, and thus the present system advantageously facilitates the control of the flow rate using a flow control device on the first flow line.

[0016] The system may comprise or take the form of a system for natural gas hydrate production, and the system is configured to separate the water component from a multiphase mixture of natural gas and water present within the wellbore. In particular, the system may comprise or take the form of a system for methane hydrate production, and the system is configured to separate the water component from a multiphase mixture of methane gas and water present within the wellbore.

[0017] As described above, the system comprises a first flow line disposed within the wellbore, and the flow line is arranged such that the inlet of the first flow line is disposed within the water component of the multiphase mixture of the gas and water to receive the water component.

[0018] The inlet of the first flow line may form the distal end of the first flow line.

[0019] Alternatively, the inlet may include one or more lateral flow ports in the first flow line.

[0020] The system may be configured such that the inlet of the first flow line is disposed below the hydrate layer. Advantageously, this facilitates the entry of water rather than a multiphase mixture of gas and water.

[0021] The first flow line may be defined as a water flow line.

[0022] The system may comprise a single first flow line.

[0023] Alternatively, the system may comprise a plurality of first flow lines.

[0024] As described above, the system comprises a flow control device provided on or operably associated with the first flow line.

[0025] The flow control device may include or take the form of a variable flow control device.

[0026] The flow control device may include or take the form of a choke.

[0027] The flow control device may include or take the form of a variable choke.

[0028] The system may include a pump.

[0029] The pump may be coupled to or operably associated with the first flow line.

[0030] The pump may be configured to draw out the water component of the multiphase mixture of gas and water present in the wellbore through the first flow line.

[0031] The pump may be configured to pump the water component of the multiphase mixture of gas and water towards the surface.

[0032] In some cases, the system may be configured such that the pump directs the water component of the gas-water multiphase mixture towards the surface.

[0033] In other examples, the system may be configured such that the pump directs the water component of the gas-water multiphase mixture towards the seabed or other location.

[0034] The pump may include, or take the form of, a single-phase pump, i.e., a pump configured to handle a single-phase fluid. The pump may include, or take the form of, a pump configured to handle liquids.

[0035] Advantageously, the system is configured to separate the water component of the gas-water multiphase mixture within the wellbore, and thus a single-phase pump can be utilized that provides better control over the flow rate through the first flow line.

[0036] However, it will be understood that the pump may alternatively include, or take the form of, a multiphase pump, i.e., a pump configured to handle a multiphase fluid.

[0037] The pump may include, or take the form of, a centrifugal pump.

[0038] The pump may include, or take the form of, a hybrid pump.

[0039] The pump may include, or take the form of, a vertical pump.

[0040] The pump may include, or take the form of, an electric submersible pump (ESP).

[0041] The control system may be configured to control a pump. The control system may be configured to communicate with a pump control system.

[0042] A flow control device, such as a choke, may be provided at the suction inlet of the pump. A flow control device, such as a choke, may be provided at the discharge outlet of the pump.

[0043] The pump may be disposed on the seabed. The pump may be disposed below the seabed. The pump may be disposed on at least one of a platform and a ship, and / or may be disposed at an intermediate position between the seabed and the surface, such as within a riser.

[0044] The pump may form a flow control device or may form part of a flow control device. The pump may include a motor. The motor speed may be variable based on the water level and / or the position of a flow control device provided on or operably associated with the first flow line so as to control the flow rate of the water component passing through the first flow line.

[0045] The system may include one or more isolation valves provided on or operably associated with the first flow line. At least one of the isolation valves may include or may be in the form of a gate valve. At least one of the isolation valves may be configured for operation by an ROV.

[0046] The system may include a second flow line. The second flow line may be disposed in a wellbore, and the second flow line is arranged such that the inlet of the second flow line is disposed in the gas component of the gas and water multiphase mixture to receive the gas component.

[0047] The inlet of the second flow line may form the distal end of the second flow line.

[0048] Alternatively, the inlet may include one or more lateral flow ports in the second flow line.

[0049] The system may include a flow control device provided on or operably associated with the second flow line.

[0050] The flow control device may include a variable flow control device or may take the form of a variable flow control device.

[0051] The flow control device may include a choke or may take the form of a choke.

[0052] The flow control device may include a variable choke or may take the form of a variable choke.

[0053] The system may include one or more isolation valves provided on or operably associated with the second flow line. At least one of the isolation valves may include an annular isolation valve or may take the form of an annular isolation valve.

[0054] As described above, the system includes a sensor configuration that includes one or more sensors configured to detect the water component level in the wellbore and output an output signal indicative of the level.

[0055] The sensor configuration may include one or more sensors configured to detect a minimum level. The sensor configuration may include one or more sensors configured to detect a maximum level.

[0056] The sensor configuration may include one or more digital sensors. The one or more digital sensors may be configured to detect the water level of the water component in the shaft hole. The sensor configuration may include one or more analog sensors. The one or more analog sensors may be configured to detect the water level of the water component in the shaft hole. The sensor configuration may include one or more optical sensors, such as optical fiber sensors. The one or more optical sensors may be configured to detect the water level of the water component in the shaft hole. The one or more optical fiber sensors may be configured to measure, for example, changes in temperature. The sensor array may include a distributed temperature sensing (DTS) sensor configuration. The DTS sensor configuration may be configured to detect the water level of the water component in the shaft hole.

[0057] The sensor configuration may include one or more pressure and / or temperature sensors. The one or more pressure and / or temperature sensors may be configured to detect the water level of the water component in the shaft hole. In particular, the sensor configuration may include a plurality (i.e., two or more) of pressure and / or temperature sensors. The pressure and / or temperature sensors may comprise a downhole pressure and temperature (DHPT) gauge or may be in the form of a DHPT gauge. The system may be configured to measure pressure with two or more of the plurality of pressure and / or temperature sensors. Since the distance between the sensors is known, the water level can be easily determined.

[0058] The sensor configuration may include one or more erosion sensors.

[0059] The sensor configuration may include one or more flow sensors.

[0060] The sensor configuration may include one or more position sensors, such as choke position sensors, of a flow control device provided on or operably associated with a first flow line.

[0061] The system may include one or more check valves. At least one of the check valves may include, or may be in the form of, a gravity check valve. At least one of the check valves may include, or may be in the form of, a ball valve.

[0062] At least one of the check valves may be provided on a first flow line. The check valve provided on the first flow line may be configured to prevent or limit backflow of water through the first flow line, i.e., backflow towards the inlet.

[0063] The check valve may be interposed between the inlet of the first flow line and a flow control device provided on the first flow line or operably associated with the first flow line.

[0064] The check valve may be disposed downstream of a flow control device provided on the first flow line or operably associated with the first flow line.

[0065] At least one of the check valves may be provided on a second flow line. The check valve provided on the second flow line may be configured to prevent or limit backflow of gas through the second flow line, i.e., backflow towards the inlet. The check valve may be interposed between the inlet of the second flow line and a flow control device provided on the second flow line or operably associated with the second flow line.

[0066] The check valve may be disposed downstream of a flow control device provided on the second flow line or operably associated with the second flow line.

[0067] The system may include a wellhead. The first flow line may be disposed through the wellhead. The second flow line may be disposed through the wellhead.

[0068] The system may include a tubing hanger. The tubing hanger may be disposed above the wellhead and / or supported by the wellhead. The first flow line may be disposed through the tubing hanger. The second flow line may be disposed through the tubing hanger.

[0069] The system may include a cap. The cap may include a tree, such as a Christmas tree, or form a part of the tree, or take the form of a tree. The cap may be coupled and / or attached to the wellhead. The first flow line may be disposed through the cap. The second flow line may be disposed through the cap.

[0070] The system may include one or more control lines and / or communication lines. For example, the system may include one or more hydraulic lines. Alternatively or additionally, the system may include one or more electrical wires. Alternatively or additionally, the system may include one or more fiber optic lines. The control lines and / or communication lines may be provided to supply power and / or communicate with tools and equipment disposed within and / or forming a part of the wellbore.

[0071] One or more control lines and / or communication lines may be disposed through the tubing hanger, wellhead, and / or cap.

[0072] One or more control lines and / or communication lines may be disposed through a tubing hanger coupler.

[0073] One or more control lines and / or communication lines may be disposed through a vertical clamp connection system (VCCS), such as a VCCS seal plate, or other means.

[0074] The system may include a manifold.

[0075] The first flow line (or, if the system comprises a plurality of first flow lines, at least one of the first flow lines) may be coupled to the manifold.

[0076] The second flow line (or, if the system comprises a plurality of first flow lines, at least one of the second flow lines) may be coupled to the manifold.

[0077] The control system may form a subsea well control system or may form part of a subsea well control system.

[0078] The control system may comprise a control module, in particular, but not exclusively, a subsea control module.

[0079] The control system, in particular the subsea control module, may be configured and / or operable to monitor the water level and control the flow rate so as to maintain an optimal level.

[0080] The control system, in particular the subsea control module, may be configured to receive sensor data from one or more water level sensors.

[0081] The control system, in particular the subsea control module, may be configured to receive sensor data from one or more erosion sensors.

[0082] The control system, in particular the subsea control module, may be configured to receive sensor data from one or more flow rate sensors.

[0083] The control system, in particular the subsea control module, may be configured to receive sensor data from one or more choke position sensors.

[0084] The control system, in particular the subsea control module, may be configured to receive sensor data from one or more pressure and / or temperature sensors.

[0085] A control system, particularly a subsea control module, processes sensor data received from one or more sensors of a sensor configuration, and may be configured to output one or more command signals to a position controller and / or an actuator of a flow control device provided on or operably associated with a first flow line to control the position of the flow control device.

[0086] For example, a control system, particularly a subsea control module, processes sensor data received from at least one of one or more water level sensors, one or more erosion sensors, one or more flow sensors, one or more position sensors of a flow control device provided on or operably associated with a first flow line, and / or at least one of one or more pressure and / or temperature sensors, and may be configured to output one or more command signals to a position controller and / or an actuator of a flow control device provided on or operably associated with a first flow line to control the position of the flow control device.

[0087] Alternatively or additionally, a control system, particularly a subsea control module, processes sensor data received from one or more sensors of a sensor configuration, and may be configured to output one or more command signals to a position controller and / or an actuator of at least one of isolation valves provided on or operably associated with a first flow line to control the position of the isolation valve.

[0088] For example, a control system, particularly a subsea control module, Process the sensor data received from at least one of the one or more water level sensors, one or more erosion sensors, one or more flow sensors, one or more position sensors of a flow control device provided on or operably associated with a first flow line, and / or at least one of the one or more pressure and / or temperature sensors. It may be configured to output one or more command signals to at least one position controller and / or actuation mechanism of the isolation valve(s) to control the position of the isolation valve(s) provided on or operably associated with the first flow line.

[0089] The system may comprise a master control station or module, may be coupled to the master control station or module, or may communicate with the master control station or module.

[0090] The master control station or module may form part of the control system of the system or may take the form of a separate system with which the control system communicates.

[0091] The control module may be configured to communicate with the master control station or module.

[0092] The master control station may be configured to receive information from one or more topside systems or modules.

[0093] For example, the master control station may be configured to receive information from an emergency shut down (ESD) system or module.

[0094] For example, the master control station may be configured to receive information from a system flow requirement system or module.

[0095] A control system, particularly a master control station or a module, may be configured to process information from at least one of one or more topside systems or modules, such as an emergency stop module and a system flow rate requirement module, and output one or more command signals to a pump controller, particularly a speed controller.

[0096] The system may include a pump control system, particularly a subsea pump control system, may be coupled to the pump control system, or may communicate with the pump control system.

[0097] The pump control system may include a pump control module. The pump control system may include a processor or may be in the form of a processor.

[0098] The pump control system may include one or more sensors associated with the control of the pump.

[0099] The pump control system may include one or more actuators associated with the control of the pump.

[0100] The pump control module may communicate with a speed controller of the pump.

[0101] The pump control module may communicate with at least one of one or more sensors associated with the control of the pump and one or more actuators associated with the control of the pump.

[0102] As described above, the system includes a flow control device provided on or operably associated with a first flow line.

[0103] The flow control device may be disposed within the wellbore. The flow control device may be disposed in the sea. The flow control device may be coupled to the cap or may form part of the cap. The flow control device may be coupled to the wellhead or may form part of the wellhead. The flow control device may be disposed upstream of the wellhead, for example, on a flow line disposed between the wellhead and the surface.

[0104] As described above, the system may include a flow control device provided on or operably associated with a second flow line.

[0105] The flow control device may be disposed within the wellbore. The flow control device may be disposed on the seabed. The flow control device may be coupled to the cap or may form part of the cap. The flow control device may be coupled to the wellhead or may form part of the wellhead. The flow control device may be disposed upstream of the wellhead, for example, on a flow line disposed between the wellhead and the surface.

[0106] According to a second aspect, there is provided a well system including the system for hydrate production of the first aspect.

[0107] The well system may include an offshore well system.

[0108] The well system may include a plurality of wellbores.

[0109] A third aspect relates to the use of a system for hydrate production according to the first aspect or a well system according to the second aspect for separating a water component from a multiphase mixture of gas and water present in a wellbore, the system being configured such that the separation is carried out within the wellbore.

[0110] The method may include the step of depressurizing the hydrate from a solid state to a multiphase mixture of gas and water.

[0111] Alternatively or additionally, the method may include the step of heating and / or injecting a medium for dissociating the gas.

[0112] The present invention is defined by the appended claims. However, for the purposes of the present disclosure, it will be understood that any of the features defined above or described below may be used alone or in combination. For example, the features described above in connection with one of the above aspects, or the features described below in connection with the following detailed description, may be used in any other aspect or may together form a new aspect. Brief Description of the Drawings

[0113] These and other aspects are described herein by way of example only with reference to the accompanying drawings.

[0114]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0115] Detailed Description of the Drawings Referring initially to FIGS. 1 and 2 of the accompanying drawings, a schematic view of a system 10 for hydrate production is shown. The exemplary system 10 is for methane hydrate production.

[0116] In use, as further described below, the system 10 is configured to separate a water component W from a multiphase mixture M of methane gas and water present in a wellbore 12, and the system 10 is configured such that the separation occurs within the wellbore 12.

[0117] As shown in FIG. 1, the system includes a first flow line 14 disposed within the wellbore 12, and the first flow line 14 is arranged such that an inlet 16 of the first flow line 14 is disposed within the water component W to receive the water component W for separating the water component W from the multiphase mixture M of methane gas and water.

[0118] In the exemplary 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.

[0119] However, it will be understood that the inlet may alternatively or additionally include one or more lateral flow ports within the first flow line 14. Also, although the system 10 includes a single flow line 14, the system 10 may alternatively include a plurality of first flow lines 14.

[0120] As shown in FIG. 1, the system 10 further includes a flow control device 18 provided on or operably associated with the first flow line 14.

[0121] In the exemplary system 10, the flow control device 18 takes the form of a variable flow control device, more specifically a variable choke.

[0122] The system 10 further includes a check valve 20. In the exemplary system 10, the check valve 20 includes or takes the form of a ball valve.

[0123] The check valve 20 is provided on the first flow line 14 and is configured to prevent or limit the reverse flow of the water component W through the first flow line 14, i.e., the reverse flow towards the inlet 16. In the exemplary system 10, the check valve 20 is interposed between the inlet 16 of the first flow line 14 and the flow control device 18.

[0124] The system 10 further comprises a sensor configuration including sensors 22, 24 configured to detect the water level of the water component W in the wellbore 12 and output an output signal indicating the water level.

[0125] In the exemplary 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 the first wellbore location. The sensor 24 measures the pressure and / or temperature at the second wellbore location. Since the distance between the sensor 22 and the sensor 24 is known, the water level can be easily determined. However, it will be understood that other suitable sensors for measuring the water level may be used.

[0126] As shown in FIG. 1, the system 10 comprises a pump 26 coupled to or operably associated with the first flow line 14.

[0127] The pump 26 is configured to draw the water component W from the wellbore 12 through the first flow line 14.

[0128] In the exemplary system 10, the pump 26 includes or takes the form of a single-phase centrifugal pump, i.e., a pump configured to handle a single-phase fluid.

[0129] Advantageously, the system 10 is configured to separate the water component W of the multiphase mixture M of water and methane gas in the wellbore 12, and thus a single-phase pump such as the pump 26 that provides better control over the flow rate through the first flow line 14 can be utilized.

[0130] As shown in FIG. 1, system 10 includes a second flow line 28. The second flow line 28 is disposed within the shaft hole 12, and the inlet 30 of the second flow line 28 is disposed within the methane gas component G of the multiphase mixture M of methane gas and water to receive the methane gas component G.

[0131] In the illustrated system 10, the inlet 30 of the second flow line 28 forms the distal end of the second flow line 28.

[0132] However, it will be understood that the inlet 30 may alternatively or additionally include one or more lateral flow ports within the second flow line 28. Also, although the system 10 includes a single flow line 28, the system 10 may alternatively include a plurality of second flow lines 28.

[0133] As shown in FIG. 1, system 10 includes a flow control device 32 provided on or operably 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 specifically a variable choke.

[0134] System 10 further includes an isolation valve 34 provided on or operably associated with the second flow line 28. In the illustrated system 10, the isolation valve 34 takes the form of an annular isolation valve.

[0135] As shown in FIG. 1 and also referring now to FIGS. 2 and 3 of the accompanying drawings, system 10 further includes a cap 36. The cap 36 is coupled and / or attached to the wellhead 38 (shown in FIG. 2), and as shown in FIG. 2, in the illustrated system 10, it can be seen that the first flow line 14 and the second flow line 28 are disposed through the wellhead 38.

[0136] As shown in FIG. 2, the system 10 further includes a tubing hanger 40. The tubing hanger 40 is disposed on and / or supported by the wellhead 38. The first flow line 14 and the second flow line 28 are disposed through the tubing hanger 40.

[0137] As shown in FIG. 3 of the accompanying drawings, the system 10 includes a flow meter 42, which takes the form of a single-phase flow meter in the exemplary system 10.

[0138] As shown in FIGS. 2 and 3, the system 10 further includes a valve 44 suitable for opening and closing the first flow line 14, which takes the form of a ROV-operable gate valve in the exemplary system 10.

[0139] As shown in FIG. 4 of the accompanying drawings, the system 10 further includes a manifold 48. As shown in FIG. 4, the first flow line 14 supplies to the aquatic production header 47, and the second flow line 28 supplies to the gas production header 49.

[0140] Next, referring to FIG. 5 of the accompanying drawings, a schematic diagram of the control system 50 of the system 10 shown in FIG. 1 is shown.

[0141] The control system 50 is configured to receive an output signal indicating the water level from the sensor configuration and control the flow control device 18 based on the water level to control the flow rate of the water component W through the first flow line 14. In the exemplary system 10, the control system 50 forms or forms part of a subsea well control system.

[0142] As shown in FIG. 5, the control system 50 includes a control module 52, which takes the form of a subsea control module in the exemplary control system 50.

[0143] The subsea control module 52 is configured to process sensor data received from at least one of the sensors of the sensor configuration (and / or any other input to the subsea control module 52) and output one or more command signals to the position controller 60 of the choke 18 to control the position of the choke 18 and to the position controller 62 of the isolation valve 46 to control the position of the isolation valve 46. In the exemplary system 10, the subsea control module 52 is configured to process sensor data received from one or more water level sensors 22, 24, one or more erosion sensors 54, one or more flow sensors (such as the flow meter 42), one or more choke position sensors 56, and one or more pressure and / or temperature sensors 58.

[0144] As shown in FIG. 5, the control system 50 includes 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.

[0145] The master control station or module 64 is configured to receive information from one or more topside systems or modules. In the exemplary system 10, the master control station or module 64 is configured to receive information from an emergency shutdown (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 various other sources in addition to, or as an alternative to, the emergency shutdown (ESD) system or module 66 and the system flow demand system or module 68.

[0146] The master control station or module 64 is configured to process information from one or more topside modules, such as the emergency shutdown module 66 and the system flow demand module 68 (and / or any other input to the master control station or module 64), and output one or more command signals to the controller 70 of the pump 28 (shown in FIG. 1), particularly the speed controller.

[0147] The control system 50 comprises, is coupled to, or communicates with a pump control system 72, which takes the form of a subsea pump control system in the exemplary system 10.

[0148] The pump control system 72 includes a pump control module. The pump control system 72 includes or takes the form of a processor.

[0149] The pump control module 74 communicates with one or more sensors associated with the control of the pump and one or more actuators (collectively represented by reference numeral 76 in FIG. 6) associated with the control of the pump.

[0150] System 10 provides several important advantages over conventional equipment and methodologies.

[0151] For example, system 10 utilizes 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.

[0152] Furthermore, conventional equipment and methodologies involve transporting a multiphase mixture that can reform into hydrates at the pressure and temperature conditions typically found subsea, as described above, to the surface. In contrast, in the present system, the separation occurs within the wellbore, thus eliminating or at least significantly reducing the risk of hydrate reformation. This improves the availability and / or efficiency of the methane hydrate production system, reduces the downtime associated with modification work, etc., and / or reduces or eliminates the need to use chemical hydrate inhibitors, heating equipment, or other hydrate mitigation agents.

[0153] Providing a system in which separation occurs within the wellbore can achieve greater control when handling single-phase flow compared to current multiphase flow rates, thereby eliminating or at least reducing slugging and wear problems in production equipment such as piping, pumps, separators, etc., which can otherwise result from excessive water and / or sand production. Further, conventional systems require equipment capable of handling multiphase fluids, while this system can utilize equipment designed to handle single-phase fluids. Such single-phase equipment is simpler to implement and generally less expensive, and in addition provides a higher degree of control over liquid flow rates in the wellbore, reducing the risk of wellbore collapse.

[0154] Furthermore, methane hydrate is sensitive to high flow rates, and thus this system advantageously facilitates the control of flow velocity using a flow control device on the first flow line.

[0155] It will be understood that various modifications can be made without departing from the scope of the invention as defined in the "claims".

[0156] For example, FIG. 6 shows an alternative system 110 for methane hydrate production comprising a plurality of wellbores 112a, b. The exemplary system 110 shows two wellbores 112a, b. However, it will be understood that the system 110 may comprise any number of wellbores 112a, b, #.

[0157] As shown in FIG. 6, the system 110 comprises two flow lines 114a, b disposed within respective wellbores 112a, b, and the inlets 116a, b of the flow lines 114a, b are disposed within the water components Wa, b to receive the water components Wa, b in order to separate the water components Wa, b from the multiphase mixtures Ma, b of methane gas and water.

[0158] In the exemplary system 110 shown in FIG. 6, the inlets 116a, b form the distal ends of the first flow lines 114a, b.

[0159] However, it will be understood that the inlets 116a, b may alternatively or additionally include one or more lateral flow ports within the flow lines 114a, b, for example. Also, although the system 110 includes a single flow line 114a, b for each wellbore hole 112a, b, the system 110 may alternatively include a plurality of flow lines 114a, b for each wellbore hole 112a, b.

[0160] As shown in FIG. 6, the system 110 further includes flow control devices 118a, b provided on or operably associated with the flow lines 114a, b.

[0161] In the exemplary system 10, the flow rate control device 118 takes the form of a variable flow rate control device, more specifically a variable choke.

[0162] The system 110 further includes check valves 120a, b. In the exemplary system 110, the check valves 120a, b include or take the form of ball valves.

[0163] The check valves 120a, b are provided on the flow lines 114a, b and are configured to prevent or limit backflow of the water components Wa, Wb through their respective flow lines 114a, b. In the exemplary 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.

[0164] The system 110 further includes a sensor configuration including sensors 122a, b, 124a, b configured to detect the water levels of the water components Wa, b within the wellbore holes 112a, b and output an output signal indicative of the water levels.

[0165] In the exemplary system 110, the sensors 122a, b, 124a, b each take the form of downhole pressure and temperature (DHPT) gauges. Sensors 122a, b measure the pressure and / or temperature at each respective first wellbore location within wellbores 112a, b. Sensors 124a, b measure the pressure and / or temperature at each respective second wellbore location within wellbores 112a, b. Since the distance between sensors 122a, b is known and the distance between sensors 1224, b is known, the water level can be readily determined. However, it will be understood that other suitable sensors for measuring the water level may be used.

[0166] As shown in FIG. 6, system 110 includes pumps 126 coupled to or operably associated with flowlines 114a, b.

[0167] Pump 126 is configured to draw water components Wa, b from wellbores 112a, b through flowlines 114a, b.

[0168] In the exemplary system 110, pump 26 includes or takes the form of a single-phase vertical centrifugal pump, i.e., a pump configured to handle a single-phase fluid.

[0169] Advantageously, system 110 is configured to separate the water component Wa, b of the multiphase mixture Ma, b of water and methane gas within wellbores 12a, b, and thus a single-phase pump such as pump 126 can be utilized that provides better control over the flow rate through the first flowlines 114a, b.

[0170] As shown in FIG. 6, system 110 includes flowlines 128a, b. Flowlines 128a, b are disposed within wellbores 112a, b, and the inlets 130a, b of flowlines 128a, b are disposed within the methane gas components Ga, b of the multiphase mixture Ma, b of methane gas and water to receive the methane gas components Ga, b.

[0171] In the exemplary system 110, the inlets 130a, b of the flow lines 128a, b form the distal ends of the second flow lines 128a, b.

[0172] However, it will be understood that the inlets 130a, b may alternatively or additionally include one or more lateral flow ports within the flow lines 128a, b. Also, while the system 110 includes a single flow line 128a, b for each wellbore 112a, b, the system 110 may alternatively include a plurality of flow lines 128a, b for each wellbore 112a, b.

[0173] As shown in FIG. 6, the system 10 includes flow control devices 132a, b provided on or operably associated with the flow lines 128a, b.

[0174] In the exemplary system 10, the flow rate control devices 132a, b take the form of variable flow rate control devices, more specifically variable chokes.

[0175] The system 110 further includes isolation valves 134a, b provided on or operably associated with the flow lines 128a, b.

[0176] FIG. 7 shows an exemplary logic diagram of how the system of FIG. 6 may operate. As described above, the system 110 includes two wellbores 112a, b, but the system 110 may include any number of wellbores. Additional wellbores are represented by # in FIG. 7.

[0177] FIG. 8 shows a well system 1000 including the system 110 for methane hydrate production shown in FIG. 6, coupled to a container V via a riser R.

[0178] In this specification, examples are used to disclose the present invention, including preferred embodiments, and enable any person skilled in the art to practice the present invention, including making and using any device or system and performing any incorporated method. The scope of the present invention that can be patented is defined by the "claims", and other examples conceivable by a person skilled in the art may also be included. Such other embodiments 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 have equivalent structural elements that have little difference from the literal language of the "claims". Aspects from the various embodiments described, as well as other known equivalents for each such aspect, may be combined and adapted by a person skilled in the art to construct additional embodiments and techniques in accordance with the principles of this application.

Claims

1. A system for hydrate production, wherein the system is configured to separate a water component from a multiphase mixture of gas and water present in a wellbore, the system is configured such that the separation is performed within the wellbore, and the system is a first flow line disposed within the wellbore, wherein the flow line is arranged such that an inlet of the first flow line is disposed within the water component of the multiphase mixture of gas and water to receive the water component for separating the water component from the multiphase mixture of gas and water, a first flow line; a flow rate control device provided on the first flow line or operably associated with the first flow line; a sensor configuration including one or more sensors configured to detect a water level of the water component within the wellbore and output an output signal indicative of the water level; a control system configured to receive the output signal indicative of the water level from the sensor configuration and control the flow rate control device based on the water level to control a flow rate of the water component passing through the first flow line. A system comprising.

2. The system according to claim 1, wherein the flow rate control device includes a variable flow rate control device or takes the form of a variable flow rate control device.

3. The system according to claim 1 or 2, wherein the flow rate control device includes a choke or takes the form of a choke.

4. Comprising a pump coupled to the first flow line or operably associated with the first flow line, the pump being configured to draw out the water component of the multiphase mixture of gas and water present in the wellbore through the first flow line. The system according to claim 1, 2, or 3.

5. The pump includes or takes the form of one of a single-phase pump or a multiphase pump. The system according to claim 4.

6. The system according to claim 4 or 5, wherein the control system is configured to control the pump.

7. The control system includes or is coupled to or communicates with a master control station or module, and the master control station or module is configured to process information from at least one topside system or module, The system according to any one of claims 4 to 6, configured to output one or more command signals to the controller of the pump. **Claim 8**: The system according to any one of claims 1 to 7, comprising a second flow line disposed in the shaft hole, wherein an inlet of the second flow line is disposed in a gas component of the gas-liquid multiphase mixture to receive the gas component. **Claim 9**: The system according to claim 8, comprising a flow rate control device provided on the second flow line or operably associated with the second flow line. **Claim 10**: The system according to claim 9, wherein the flow rate control device includes a variable flow rate control device or takes the form of a variable flow rate control device. **Claim 11**: The system according to claim 9 or 10, wherein the flow rate control device includes a choke or takes the form of a choke. **Claim 12** The control system includes a control module, and the control module processes the sensor data received from the sensors of the sensor configuration, outputs one or more command signals to a position controller and / or an actuator mechanism of the flow rate control device for controlling the position of the flow rate control device provided on or operably associated with the first flow line, and / or outputs one or more command signals to a position controller and / or an actuator mechanism of at least one of the isolation valves for controlling the position of the isolation valve provided on or operably associated with the second flow line, and is configured to perform at least one of the above, according to any one of claims 8 to 11. **Claim 13**: The system according to any one of claims 1 to 6, wherein the control system includes, is coupled to, or communicates with a master control station or module. **Claim 14**: The sensor configuration includes one or more erosion sensors, one or more flow rate sensors, and one or more position sensors of the flow rate control device provided on or operably associated with the first flow line The system according to any one of claims 1 to 13, further comprising at least one of one or more pressure and / or temperature sensors.

15. The system according to any one of claims 1 to 14, wherein the control system comprises a pump control system, is coupled to a pump control system, or communicates with a pump control system.

16. The system according to any one of claims 1 to 15, wherein the system comprises a system for natural gas hydrate production or takes the form of a system for natural gas hydrate production, and the system is configured to separate a water component from a multiphase mixture of natural gas and water present in a wellbore.

17. The system according to any one of claims 1 to 16, wherein the system comprises a system for methane hydrate production or takes the form of a system for methane hydrate production, and the system is configured to separate a water component from a multiphase mixture of methane gas and water present in a wellbore.

18. A well system comprising the system for hydrate production according to any one of claims 1 to 17.

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

20. Use of the system for hydrate production according to any one of claims 1 to 17 or the well system according to claim 18 or 19 for separating a water component from a multiphase mixture of gas and water present in a wellbore, wherein the system is configured such that the separation is carried out in the wellbore.

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