A marine natural gas hydrate test production system and method

Abstract

The present invention discloses a system and method for offshore natural gas hydrate production testing. The system includes an emergency release assembly, a well control assembly, a wellhead adapter, a production riser, and a flow test tree. The emergency release assembly is configured to open its own pressure control valve in response to a production test instruction; the well control assembly is configured to open its own shear seal valve in response to a production test instruction; and the flow test tree is configured to receive production fluid from the decomposition of natural gas hydrates. The production fluid rises and returns from the production test well, passes through the wellhead adapter, the well control assembly, the emergency release assembly, enters the production riser, and reaches the flow test tree. The system implements offshore natural gas hydrate production testing by configuring a high-pressure, water-insulated production riser and adding an emergency release assembly, a well control assembly, and a wellhead adapter. The system also has the ability to be connected back to continue operations after emergency release, ensuring the continuity of natural gas hydrate production testing operations.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas resource development, and in particular to a system and method for testing the production of offshore natural gas hydrates. Background Art

[0002] Natural gas hydrates, also known as "combustible ice," release 164 volumes of methane gas and 0.8 volumes of water per volume. Their energy density far exceeds that of current energy sources like oil and natural gas. Combustible ice is widely distributed in deep sea and permafrost on land, and its reserves are enormous, with the most significant reserves in the ocean, making it a highly valuable resource.

[0003] To accelerate the commercial development of natural gas hydrates in offshore areas, several countries have conducted offshore natural gas hydrate production trials and testing. Conventional trial production and testing methods require the drilling platform to rent a third-party specialized underwater test tree for use. This is costly, and the on-site construction and procedures are complex. Furthermore, due to the shallow depth of the natural gas hydrate reservoir, the underwater wellhead casing is limited in depth, resulting in a limited load-bearing capacity. If the drilling platform encounters an emergency such as a typhoon and requires evacuation by releasing the upper blowout preventer, the subsea wellhead cannot bear the weight of the lower blowout preventer, causing the wellhead to sink or capsize. Furthermore, after the blowout preventer is released, it cannot be reconnected, forcing the trial production operation to be interrupted, causing immeasurable losses to the entire project. Summary of the Invention

[0004] The present invention provides a system and method for testing sea area natural gas hydrate production, which solves the problem of being able to connect back and continue operations after releasing equipment in an emergency situation during the production trial, thereby achieving the continuity of the production trial test of sea area natural gas hydrate.

[0005] According to one aspect of the present invention, an embodiment of the present invention provides a marine natural gas hydrate production test system, the system comprising an emergency release assembly, a well control assembly, a wellhead adapter, a production riser, and a flow test tree; wherein:

[0006] The wellhead adapter is configured at the wellhead of a subsea test well. The first end of the wellhead control assembly is connected to an end of the wellhead adapter away from the wellhead. The second end of the well control assembly is connected to the first end of the emergency release assembly via a connector. The connector is used to disconnect or connect the well control assembly and the emergency release assembly. The second end of the emergency release assembly is connected to a production riser. The production riser extends out of the drill floor and is connected to a flow test tree.

[0007] The emergency release assembly is equipped with a pressure control valve, and the emergency release assembly is configured to open its own pressure control valve in response to a test production instruction for the test production well;

[0008] The well control assembly is equipped with a shear seal valve, and the well control assembly is configured to open its own shear seal valve in response to a test production instruction for the test production well;

[0009] A reagent injection skid is provided on the side of the production riser extending out of the drilling floor. After the emergency release assembly opens the pressure control valve and the well control assembly opens the shear seal valve, the reagent injection skid is configured to receive an input reference reagent in response to a test production instruction for the test production well, and transmit the reference reagent to the test production well in sequence through the emergency release assembly, the well control assembly, and the wellhead adapter. The reference reagent is used to decompose natural gas hydrates in the seabed test production well.

[0010] The flow test tree is configured to receive production fluid from the decomposition of natural gas hydrates in the test well. The production fluid rises and returns from the test well, passes through the wellhead adapter, the well control assembly, the emergency release assembly, enters the production riser, and reaches the flow test tree.

[0011] According to another aspect of the present invention, an embodiment of the present invention further provides a method for testing marine natural gas hydrate production, the method comprising:

[0012] The emergency release assembly receives the production test instruction to open its own pressure control valve, and the well control assembly opens its own shear seal valve according to the production test instruction. The well control assembly receives the production test instruction via a connector with the emergency release assembly;

[0013] The control module controls the reagent injection skid to inject a reference reagent into a reagent channel of the underwater equipment assembly, wherein the underwater equipment assembly includes an emergency release assembly, a well control assembly, and a wellhead adapter;

[0014] The production fluid of natural gas hydrate decomposition in the test well is collected through a flow test tree.

[0015] The technical solution of the embodiment of the present invention realizes the trial production and testing of natural gas hydrates in the sea area by configuring a high-pressure water-proof production riser, adding an emergency release assembly, a well control assembly and a wellhead adapter dedicated to the wellhead. At the same time, it has the ability to be reconnected after emergency release to continue the trial production and testing of natural gas hydrates, thereby ensuring the continuity of the trial production and testing of hydrates, and has the advantages of simplicity, economy and sustainability.

[0016] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a diagram of a marine natural gas hydrate trial production test system provided by an embodiment of the present invention;

[0019] Figure 2 This is a structural diagram of another offshore natural gas hydrate trial production testing system provided by an embodiment of the present invention;

[0020] Figure 3 This is a flow chart of a method for testing the trial production of natural gas hydrate in offshore areas according to an embodiment of the present invention;

[0021] Figure 4 It is a flow chart of a method for testing the trial production of natural gas hydrate in sea areas according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] Figure 1 A diagram of a test system for offshore natural gas hydrate production is provided for an embodiment of the present invention. This embodiment is applicable to offshore natural gas hydrate production test situations.

[0025] like Figure 1As shown, the offshore natural gas hydrate production test system includes: emergency release assembly, well control assembly, wellhead adapter, production riser and flow test tree.

[0026] The wellhead adapter is configured at the wellhead of a submarine test well, the first end of the wellhead assembly is connected to the end of the wellhead adapter away from the wellhead, the second end of the well control assembly is connected to the first end of the emergency release assembly via a connector, the connector is used to disconnect or connect the well control assembly and the emergency release assembly, the second end of the emergency release assembly is connected to a production riser, and the production riser extends out of the drill floor and is connected to a flow test tree.

[0027] See also Figure 2 This is another diagram of a natural gas hydrate production test system in the sea area, which includes: an emergency release assembly 1, a well control assembly 2, a wellhead adapter 3, a production riser 4, a flow test tree 5 and other equipment. The configuration and connection relationship between each device is as follows: the wellhead adapter 3 is arranged at the wellhead of the seabed test well, the lower end of the well control assembly 2 is connected to the upper end of the wellhead adapter 3, and the upper end of the well control assembly 2 is connected to the lower end of the emergency release assembly 1 through a connector. The connector is used to disconnect or connect the well control assembly 2 and the emergency release assembly 1. The upper end of the emergency release assembly 1 is connected to the production riser 4, and the production riser 4 extends out of the drilling floor and is connected to the flow test tree 5.

[0028] The emergency release assembly 1 is equipped with a pressure control valve, and the emergency release assembly is configured to open its own pressure control valve in response to a test production instruction for a test production well.

[0029] It should be noted that the emergency release assembly 1 is a safety device that can be used in the event of an emergency such as a typhoon or the loss of dynamic positioning capability during a natural gas hydrate production test operation platform. In actual use, the emergency release assembly 1 must be operated to release the subsea well control assembly 2.

[0030] An important component of the emergency release assembly 1 is the connector, which is a large-angle connector equipped with a series of quick connectors such as electrical signal connectors, hydraulic connectors, and power connectors. It can be used to transmit control hydraulic pressure and signals of the well control assembly 2 and the wellhead adapter 3.

[0031] See also Figure 2 The upper end of the emergency release assembly 1 is provided with a connector to connect to the production riser 4, and the lower end of the emergency release assembly 1 is connected to the well control assembly 2 through a large-angle connector.

[0032] Among them, the emergency release assembly 1 is equipped with a pressure control valve. When conducting trial production and testing operations, it can receive trial production instructions to open its own pressure control valve, opening the channel to ensure that submarine natural gas hydrate trial production and testing operations can be carried out.

[0033] The well control assembly 2 is equipped with a shear seal valve, and the well control assembly is configured to open its own shear seal valve in response to a test production instruction for the test production well.

[0034] It should be noted that the Well Control Assembly 2 is a valve assembly used for well control. It ensures effective control of wellhead pressure during drilling, completion, workover, and production operations to prevent blowouts. Furthermore, the Well Control Assembly 2 protects the wellbore from erosion and damage by high-pressure fluids, extending its service life and providing a safe and reliable working environment for downhole production trials.

[0035] See also Figure 2 The lower end of the well control assembly 2 is connected to the wellhead connector at the upper end of the wellhead adapter 3 through a connector. Hydraulic flying wires and electric flying wires are also required to be connected between the well control assembly 2 and the wellhead adapter 3 to transmit hydraulic power and signal communication respectively.

[0036] Among them, the well control assembly 2 is equipped with a shear sealing valve. When conducting trial production and testing operations, it can receive trial production instructions to open its own shear sealing valve, opening the channel to ensure that the trial production and testing operations of submarine natural gas hydrates can be carried out.

[0037] The production riser 4 extending out of the drilling floor side is equipped with a reagent injection skid; after the emergency release assembly 1 opens the pressure control valve and the well control assembly 2 opens the shear seal valve, the reagent injection skid is configured to receive the input reference reagent in response to the test production instruction of the test well, and transmit the reference reagent to the test well in sequence through the emergency release assembly, the well control assembly and the wellhead adapter; the reference reagent is used to decompose natural gas hydrates in the seabed test well.

[0038] It should be noted that the production riser 4 is made up of pipes that are resistant to compression and tension and have sealing connection capabilities. It can connect subsea equipment and sea surface operating platforms. The production riser can be used to isolate seawater, seal pressurized gas, and serve as a channel for production fluids.

[0039] Among them, the production riser can meet the load and air tightness requirements of the operating environment at a water depth of 3,000 meters. The production riser includes standard risers, riser short sections, stress joints, wear-resistant joints, tension joints, etc.

[0040] The reagent injection skid is a device used to inject reference reagents into pipelines, wellheads, and other locations. Upon receiving the test production instructions, the skid injects the reference reagents into the test wells. The reference reagents are chemicals that can decompose natural gas hydrates in the subsea test wells while preventing them from freezing and solidifying. Commonly used chemicals for decomposing natural gas hydrates include brine, methanol, ethanol, ethylene glycol, and glycerol.

[0041] The flow test tree 5 is configured to receive production fluid from the decomposition of natural gas hydrates in the test well. The production fluid rises and returns from the test well, passes through the wellhead adapter 3, the well control assembly 2, the emergency release assembly 1, enters the production riser 4, and reaches the flow test tree 5.

[0042] See also Figure 2 The upper end of the flow test tree 5 is suspended within the derrick by a coiled tubing hoist, with its lower end connected to the production riser. Valves are located on the top, bottom, left, and right sides of the flow test tree 5, serving as return ports for production fluids. Downhole tools such as coiled tubing and slickline cables are also lowered into the test well through the upper ports of the flow test tree 5.

[0043] In addition, the coiled tubing lifting frame is a rigid connection frame, which is suspended by the top drive in the work platform derrick and is connected to the flow test tree 5 at the bottom to lift the weight of other equipment or devices.

[0044] Optionally, the emergency release assembly 1 is connected to the control module via a main control cable. The main control cable includes an optical signal line, an electrical cable and a hydraulic pipe, and is used to transmit command data sent by the control module.

[0045] For example, see Figure 2 The upper end of the emergency release assembly 1 is also connected to two umbilical cables, the main control cable and the circulating water pipe. The emergency release assembly 1 is connected to the control module through the main control cable.

[0046] Among them, the main control cable includes various optical signal lines, electrical cables and hydraulic pipes. It is the medium for the control module to control the underwater valve group module. It can not only transmit command data, but also be used for hydraulic control and the transportation of reference reagents.

[0047] Optionally, the control module is configured with an instruction sending submodule and a data monitoring submodule; wherein,

[0048] The instruction sending submodule is used to send reference instructions to the emergency release assembly 1, and the reference instructions include test production instructions and release instructions;

[0049] The data monitoring submodule is used to receive reference data sent by the wellhead adapter 2 to monitor the test production operation in the test well. The reference data includes temperature data, pressure data, power supply data and reagent injection data in the test well.

[0050] It should be noted that the control module consists of a hydraulic pump skid and a main control station, which can send and receive data and control other equipment and devices by pumping control fluid.

[0051] Specifically, the control module transmits reference instructions via the main control cable to other equipment or devices, such as the emergency release assembly 1 and the well control assembly 2. The receiving equipment or devices then respond based on the reference instructions. Reference instructions include test production instructions and release instructions. The test production instruction indicates the instructions for conducting a test production test of natural gas hydrates. After the control module transmits the test production instruction, the system begins the test production test. The release instruction indicates the instructions for emergency release in the event of an emergency. After the control module transmits the release instruction, the emergency release assembly 1 and all connected equipment are rapidly evacuated from the seabed to ensure the safety of the system, equipment, and personnel.

[0052] In actual application, the control system is connected to the wellhead adapter 3 through the main control cable and the underwater flying line. The wellhead adapter 3 is designed with optical fibers, power cables, signal cables, chemical cables and other cables required for the trial production test, which pass through the trial production well to monitor the downhole trial production operation and collect data. The collected reference data includes downhole temperature and pressure monitoring data, downhole electric submersible pump power supply data, downhole reference reagent injection data, etc. The collected reference data is transmitted to the control module for data information reading and real-time monitoring of the trial production test operation.

[0053] Optionally, the emergency release assembly 1 is configured with at least one set of main channels, circulating water channels and reagent channels, wherein the main channels are used to transport production fluids for decomposition of natural gas hydrates, the water channels are used to transport water bodies, and the reagent channels are used to transport reference reagents.

[0054] Natural gas hydrates in the subsea test well are decomposed into production fluids containing oil, gas, and water. The oil and gas are transported upward to the operating platform above the water surface through the main channel within the emergency release assembly 1, while the water is transported upward to the operating platform through the water channel within the emergency release assembly 1. Reference reagents are transported to the test well through a dedicated reagent channel to ensure that the reference reagent injection process and the production fluid collection process do not affect each other.

[0055] Optionally, the emergency release assembly 1 is configured with an emergency release instruction receiving module and an emergency release instruction responding module; wherein,

[0056] The emergency release instruction receiving module is used to receive the instruction sent by the control module;

[0057] The emergency release command response module is used to open and close the pressure control valve or disconnect the connector with the well control assembly according to the command sent by the control module.

[0058] Among them, the emergency release assembly 1 is connected to the control module through the main control cable, and can receive instructions sent by the control module and respond according to the instructions. The response actions include opening or closing its own pressure control valve or disconnecting the connector with the well control assembly 2.

[0059] Optionally, the well control assembly 2 is configured with at least one set of main channels, circulating water channels and reagent channels, the main channels are connected to the main channels of the emergency release assembly 1, the circulating water channels are connected to the water channels of the emergency release assembly 1, and the reagent channels are connected to the reagent channels of the emergency release 1 assembly.

[0060] Natural gas hydrates in the subsea test well are decomposed into production fluids containing oil, gas, and water. The oil and gas are transported upward to the operating platform above the water surface through the main channel within the well control assembly 2, while the water is transported upward to the operating platform through the water channel within the well control assembly 2. Reference reagents are transported to the test well through a dedicated reagent channel, ensuring that the reference reagent injection process and the production fluid collection process do not affect each other.

[0061] Optionally, the well control assembly 2 is configured with a well control instruction receiving module and a well control instruction responding module; wherein,

[0062] The well control command receiving module is used to receive the command transmitted by the emergency release assembly;

[0063] The well control instruction response module is used to close or open its own shear sealing valve according to the instruction.

[0064] Among them, the well control assembly 2 is connected to the emergency release assembly 1 through a connector, and can receive instructions sent by the control module and respond according to the instructions. The response actions include opening and closing its own shear sealing valve, and shearing off the operating tool while closing the shear sealing valve.

[0065] Optionally, the wellhead adapter 3 is provided with an oil pipe hanging short circuit and a water pipe short circuit near one end of the wellhead. The oil pipe hanging short circuit is connected to the production oil pipe in the test well for transporting the production fluid of natural gas hydrate decomposition, and the water pipe short circuit is connected to the water pipe in the test well for transporting water.

[0066] Oil pipe suspension shorting and water pipe shorting are two types of shorting components used to connect pipelines. Oil pipe suspension shorting is typically made of high-strength steel with excellent corrosion and wear resistance. Oil pipe suspension shorting connects production pipelines to transport oil and gas, ensuring stability and safety during the transportation process.

[0067] Water pipe short circuits are usually made of plastic or metal, with good corrosion resistance and wear resistance. Water pipe short circuits connect water pipes to transport water bodies, ensuring stability and safety during the water transportation process.

[0068] The technical solution of this embodiment realizes the trial production and testing of submarine natural gas hydrates by configuring a high-pressure water-proof production riser, adding an emergency release assembly, a well control assembly and a wellhead adapter dedicated to the wellhead. At the same time, it has the ability to be reconnected after emergency release to continue the trial production and testing of natural gas hydrates, thereby ensuring the continuity of the trial production and testing operations of hydrates and effectively reducing operating costs. In addition, each device is small in size, light in weight and easy to operate, which can effectively improve the efficiency of the trial production and testing operations of hydrates.

[0069] Figure 3 The flowchart of a method for testing the production of natural gas hydrate in offshore areas is provided to realize the embodiment of the present invention. This embodiment is applicable to the testing of natural gas hydrate in offshore areas. Figure 3 As shown, the method includes:

[0070] S110. The emergency release assembly receives a production test instruction to open its own pressure control valve. The well control assembly opens its own shear seal valve according to the production test instruction. The well control assembly receives the production test instruction through a connector with the emergency release assembly.

[0071] The control module sends the production test command to each device. The emergency release assembly receives the command via the main control cable and opens its own pressure control valve according to the hydraulic control in the main control cable. The emergency release assembly transmits the production test command signal to the well control assembly via a connector. Upon receiving the production test command, the well control assembly opens its shear seal valve, keeping the main channel, circulating water channel, and reagent channel of the emergency release assembly and well control assembly unobstructed.

[0072] S120. The reagent injection skid receives a production test instruction and injects a reference reagent into a reagent channel of the underwater equipment assembly, wherein the underwater equipment assembly includes an emergency release assembly, a well control assembly, and a wellhead adapter.

[0073] Among them, the reagent injection skid is connected to the control module through the cable on the deck. After receiving the test production instruction, the reagent injection skid transports the reference reagent to the emergency release assembly through the hydraulic pipe in the main control cable. The reagent flows from the reagent channel of the emergency release assembly to the reagent channel of the well control assembly and enters the test production well through the wellhead adapter.

[0074] S130. Collect the production fluid of the decomposed natural gas hydrate in the test well through a flow test tree.

[0075] Among them, the reference reagent reacts with natural gas hydrates in the test well, decomposing and producing production fluids containing oil, gas and water. The decomposed oil and gas flow from the production oil pipe to the main channel of the wellhead adapter, pass through the main channel of the well control assembly and the main channel of the emergency release assembly, enter the production riser, and are transported by the production riser to the flow test tree on the deck. The oil and gas are returned from one end of the flow test tree for collection.

[0076] The technical solution of the present invention realizes the trial production and testing of natural gas hydrates in offshore areas by adding an emergency release assembly, a well control assembly and a wellhead adapter dedicated to the wellhead, and has the advantages of being simple, economical and sustainable.

[0077] Figure 4 In order to realize the flow chart of a method for testing the trial production of natural gas hydrate in sea area according to the embodiment of the present invention, this embodiment can be applied to the emergency release situation during the trial production and testing of natural gas hydrate in sea area. Figure 4 As shown, the method includes:

[0078] S210. The emergency release assembly receives a release instruction to close its own pressure control valve, and the well control assembly closes its own shear seal valve according to the release instruction. The well control assembly receives the release instruction through a connector with the emergency release assembly.

[0079] The control module sends the release command to each device. The emergency release assembly receives the release command from the control module via the main control cable and closes its own pressure control valve based on the hydraulic control in the main control cable. The emergency release assembly transmits the release command signal to the well control assembly via a connector. Upon receiving the release command, the well control assembly closes its shear seal valve and shears off the test production tool. The main channel, circulating water channel, and reagent channel of the emergency release assembly and well control assembly remain sealed.

[0080] S220: The emergency release assembly controls the connector with the well control assembly to be disconnected according to the release instruction.

[0081] After sealing the channel, the emergency release assembly must quickly disconnect from the well control assembly according to the release command. The emergency release assembly and its connected production riser are then lifted from the seabed and hoisted to a safe height by a coiled tubing hoist. The assembly is then evacuated to a safe area along with the test vessel for the production trial.

[0082] After release, the test wellhead is connected to the wellhead adapter and well control assembly to seal and protect the test well. The subsea test wellhead's support equipment is lightweight and poses no threat to the wellhead. The released equipment can be reconnected to the subsea wellhead via the connector between the emergency release assembly and the well control assembly, enabling the production channel, hydraulic control, and signal connection to continue with the subsea natural gas hydrate test and production operations, ensuring continuity.

[0083] The technical solution of the embodiment of the present invention realizes the emergency release function during the trial production and testing of submarine natural gas hydrates by configuring an emergency release assembly, a well control assembly and a wellhead adapter dedicated to the wellhead. It also has the ability to be reconnected after release to continue the trial production and testing of natural gas hydrates, thereby ensuring the continuity of the trial production and testing of hydrates, and has the advantages of simplicity, economy and sustainability.

[0084] Through the above description of the implementation methods, those skilled in the art can clearly understand that the embodiments of the present invention can be implemented with the help of software and necessary general-purpose hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solutions of the embodiments of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory (FLASH), hard disk or optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0085] It is worth noting that in the embodiment of the above system, the various structures included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the various functional structures are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0086] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the embodiments of the present invention have been described in more detail through the above embodiments, the embodiments of the present invention are not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments may be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A marine natural gas hydrate production test system, characterized in that: The system includes an emergency release assembly, a well control assembly, a wellhead adapter, a production riser, and a flow test tree; wherein: The wellhead adapter is configured at the wellhead of a subsea test well. The first end of the wellhead control assembly is connected to an end of the wellhead adapter away from the wellhead. The second end of the well control assembly is connected to the first end of the emergency release assembly via a connector. The connector is used to disconnect or connect the well control assembly and the emergency release assembly. The second end of the emergency release assembly is connected to a production riser. The production riser extends out of the drill floor and is connected to a flow test tree. The emergency release assembly is equipped with a pressure control valve, and the emergency release assembly is configured to open its own pressure control valve in response to a test production instruction for the test production well; The well control assembly is equipped with a shear seal valve, and the well control assembly is configured to open its own shear seal valve in response to a test production instruction for the test production well; A reagent injection skid is provided on the side of the production riser extending out of the drilling floor. After the emergency release assembly opens the pressure control valve and the well control assembly opens the shear seal valve, the reagent injection skid is configured to receive an input reference reagent in response to a test production instruction for the test production well, and transmit the reference reagent to the test production well in sequence through the emergency release assembly, the well control assembly, and the wellhead adapter. The reference reagent is used to decompose natural gas hydrates in the seabed test production well. The flow test tree is configured to receive production fluid from the decomposition of natural gas hydrates in the test well. The production fluid rises and returns from the test well, passes through the wellhead adapter, the well control assembly, the emergency release assembly, enters the production riser, and reaches the flow test tree.

2. The system according to claim 1, wherein: The emergency release assembly is connected to the control module via a main control cable. The main control cable includes an optical signal line, an electrical cable and a hydraulic pipe for transmitting command data sent by the control module.

3. The system according to claim 2, characterized in that The control module is configured with an instruction sending submodule and a data monitoring submodule; wherein, The instruction sending submodule is used to send instructions to the emergency release assembly, the well control assembly and the wellhead adapter, and the instructions include test production instructions and release instructions; The data monitoring submodule is used to receive reference data sent by the wellhead adapter to monitor the test production operation in the test well. The reference data includes temperature data, pressure data, power supply data and reagent injection data in the test well.

4. The system according to claim 1, wherein: The emergency release assembly is configured with at least one set of main channels, circulating water channels and reagent channels. The main channels are used to transport production fluids for decomposing natural gas hydrates, the water channels are used to transport water bodies, and the reagent channels are used to transport reference reagents.

5. The system according to claim 4, characterized in that The emergency release assembly is configured with an emergency release instruction receiving module and an emergency release instruction responding module; wherein, The emergency release instruction receiving module is used to receive the instruction sent by the control module; The emergency release command response module is used to open and close the pressure control valve or disconnect the connector with the well control assembly according to the command sent by the control module.

6. The system according to claim 1, wherein: The well control assembly is configured with at least one set of main channels, circulating water channels and reagent channels. The main channels are connected to the main channels of the emergency release assembly, the circulating water channels are connected to the water channels of the emergency release assembly, and the reagent channels are connected to the reagent channels of the emergency release assembly.

7. The system according to claim 6, characterized in that The well control assembly is configured with a well control instruction receiving module and a well control instruction responding module; wherein, The well control command receiving module is used to receive the command transmitted by the emergency release assembly; The well control instruction response module is used to close or open its own shear sealing valve according to the instruction.

8. The system according to claim 1, wherein: The wellhead adapter is equipped with an oil pipe hanging short circuit and a water pipe short circuit at one end near the wellhead. The oil pipe hanging short circuit is connected to the production oil pipe in the test well for transporting the production fluid of natural gas hydrate decomposition, and the water pipe short circuit is connected to the water pipe in the test well for transporting formation water.

9. A method for testing sea area natural gas hydrate production trial, applied to the sea area natural gas hydrate production trial testing system according to any one of claims 1 to 8, characterized in that: include: The emergency release assembly receives the production test instruction to open its own pressure control valve, and the well control assembly opens its own shear seal valve according to the production test instruction. The well control assembly receives the production test instruction via a connector with the emergency release assembly; The reagent injection skid receives a test production instruction and injects a reference reagent into a reagent channel of a subsea equipment assembly, wherein the subsea equipment assembly includes an emergency release assembly, a well control assembly, and a wellhead adapter; The production fluid of natural gas hydrate decomposition in the test well is collected through a flow test tree.

10. The method according to claim 9, characterized in that Also includes: The emergency release assembly receives the release command to close its own pressure control valve, and the well control assembly closes its own shear seal valve according to the release command. The well control assembly receives the release command via a connector with the emergency release assembly. The emergency release assembly controls the connector of the well control assembly to be disconnected according to the release instruction.

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