Natural gas hydrate multi-gas commingling production experimental device
By designing a multi-gas production experimental device for natural gas hydrate, simulating different mining processes and monitoring gas-aquatic output, the problem of unclear gas-aquatic output behavior and control factors in multi-gas production is solved, and the natural gas hydrate is achieved-under-the-wall Safe and efficient control of gas reservoir reduction and mining process.
Patent Information
- Application Number
- CN202421017732.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-11
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2034-05-11
AI Technical Summary
In the existing natural gas hydrate mining technology, the main control factors of gas-aqueous output behavior and gas-aqueous recovery rate during multi-gas mining are unclear, resulting in problems such as low gas production rate, excessive water production and formation settlement, which are difficult to achieve long-term Stable commercial mining.
A natural gas hydrate multi-gas production experimental device was designed, including a high-pressure natural gas hydrate generation system, a high-pressure undercurrent system stabilization system, a real-time quantitative system for gas-liquid output and a controllable pressure-down mining system, and a controlled reduction mining system by simulating different mining processes. , monitor gas and aquatic output and regulate bottom well flow pressure to realize quantitative monitoring of gas and aquatic output and the impact of different pressure reduction rates on mining behavior.
The reduction of the natural gas hydrate-underground gas reservoir allocation system was achieved, the multi-gas combined production process was simulated, the gas and water output was quantitatively monitored, and the gas and water content control mechanism of the underlying gas layer during the pressure-reducing multi-gas combined production process was studied. Provides safe and efficient control of the mining process.
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Figure CN222207877U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of natural gas hydrate exploitation, in particular to a natural gas hydrate multi-gas combined exploitation experimental device. Background Art
[0002] Natural gas hydrate is an ice-like solid crystalline substance formed under low temperature and high pressure. In it, water molecules are connected to each other through hydrogen bonds to form a cage-like structure, which encapsulates molecules with methane (CH4) as the main component and maintains stability through van der Waals forces.
[0003] Gas hydrates are widely distributed in the natural environment, mainly in permafrost on land and shallow sediments at the edge of the continental shelf in the sea. They have the characteristics of high energy density, large reserves, low pollution and wide distribution, and are therefore regarded as resources with extremely high commercial mining value. It is estimated that the global gas hydrate reserves are about 300 trillion cubic meters, and they are considered to be a potential clean energy alternative in the future. Currently, the following four types of hydrate deposits are considered to be the most promising targets for natural gas recovery: Type 1 gas hydrate deposits consist of two layers: a two-phase fluid zone of free gas in the lower part (i.e., the underlying gas layer) and a gas hydrate-containing layer in the upper part; Type 2 gas hydrate deposits include two areas: an upper water-containing overburden and a lower gas hydrate-containing layer; Type 3 gas hydrate deposits consist of a single gas hydrate-containing layer, and the upper and lower strata do not contain freely flowing fluids; Type 4 gas hydrate deposits are characterized by the absence of typical water-containing overburden and underlying gas layers of Types 1-3. Among them, Type 1 natural gas hydrate deposits are widely distributed in marine natural gas hydrate storage areas, including my country's South China Sea, and have huge mining potential.
[0004] The process of gas hydrate extraction involves disturbing the stable state of the reservoir and destroying the thermodynamic equilibrium of the hydrate to induce the decomposition of the hydrate, thereby releasing and recovering the natural gas. Existing extraction technologies include pressure reduction, heat injection, inhibitor injection, and carbon dioxide (CO2) replacement. So far, China has conducted trial production of Class 1 gas hydrate deposits in the Shenhu area of the South China Sea, achieving continuous gas production for 30 days, verifying the feasibility of developing Class 1 gas hydrate deposits.
[0005] However, there is still a certain gap between the current natural gas hydrate trial production and long-term stable commercial production, which is mainly manifested in unfavorable production phenomena such as low gas production rate, excessive water production, sand production, and formation subsidence during the production process. This is mainly due to the limited understanding of the multi-gas production of Class 1 natural gas hydrate deposits, namely the natural gas hydrate-underlying gas reservoir system, and the unclear main controlling factors of gas and water production behavior and gas and water recovery rate in the multi-gas production project. Therefore, it is crucial to restore the natural gas hydrate-underlying gas reservoir system and study the gas and water production mechanism and control factors during the multi-gas production process to ensure safe and efficient production. However, large-scale production tests are costly and time-consuming, and it is difficult to accurately control key parameters such as lithology, depressurization rate, and bottom hole pressure. The current methods for studying subsidence during the production process are mostly numerical simulations, lacking experimental verification.
[0006] Therefore, it is urgent to develop a natural gas hydrate multi-gas co-production experimental device to restore the natural gas hydrate-underlying gas reservoir system, and simultaneously realize the production processes such as multi-gas co-production in the natural gas hydrate layer, production between the natural gas hydrate and the underlying gas layer, and multi-gas co-production in the underlying gas layer, so as to clarify how different decompression rates and decompression gradients affect the decomposition of natural gas hydrates and fluid production behavior under different hydrate saturations. Utility Model Content
[0007] The technical problem to be solved by the utility model is to propose a natural gas hydrate multi-gas co-production experimental device, so as to restore the natural gas hydrate-underlying gas reservoir occurrence conditions, realize different multi-gas co-production, and conduct quantitative monitoring of gas and water output.
[0008] The technical problem of the utility model is solved by the following technical solutions:
[0009] A natural gas hydrate multi-gas co-production experimental device, which is used to simulate three different production processes: multi-gas co-production of natural gas hydrate layers, multi-gas co-production of underlying gas layers, and production between natural gas hydrates and underlying gas layers. It includes a high-pressure natural gas hydrate generation system, a high-pressure underlying gas system stabilization system, a gas-liquid output real-time quantitative system, a controllable pressure reduction production system, a water injection device, a gas injection device, a combination valve, a first control valve, and a second control valve; wherein: the high-pressure natural gas hydrate generation system is used to synthesize natural gas hydrate sediment samples, and has a first production port on the upper part and a third production port on the lower part; the high-pressure underlying gas system stabilization system is used to prepare samples simulating underlying gas layer sediments, and is arranged in the high-pressure Below the natural gas hydrate generation system, its upper part is connected to the third mining port of the high-pressure natural gas hydrate generation system through the combination valve, and the lower part has a second mining port; the controllable pressure reduction mining system is used to regulate the bottom hole flow pressure in the three mining processes, which are respectively: connected to the first mining port through the first control valve, connected to the second mining port through the second control valve, and connected to the third mining port through the combination valve; the gas-liquid output real-time quantitative system is connected to the controllable pressure reduction mining system; the water injection device and the gas injection device are respectively connected to the high-pressure natural gas hydrate generation system and the high-pressure underlying gas system stabilization system through the combination valve.
[0010] Preferably, the high-pressure natural gas hydrate generation system also includes a first constant temperature water bath device, a first pressure sensor, a second pressure sensor, a third pressure sensor, a first temperature sensor, a high-pressure reactor (25), a first sand control device, and a second sand control device; wherein: the first mining port is located at the upper part of the high-pressure reactor, and the third mining port is located at the lower part of the high-pressure reactor; the first constant temperature water bath device is connected to the high-pressure reactor for controlling the temperature inside the high-pressure reactor; the first pressure sensor and the second pressure sensor are located at the top of the high-pressure reactor, and the third pressure sensor is located at the bottom of the high-pressure reactor; the first sand control device is arranged between the first control valve and the first mining port, the second sand control device is arranged in the third mining port, and the first temperature sensor is used to monitor the changes in the internal temperature field of the high-pressure reactor.
[0011] Preferably, the high-pressure underlying gas system stabilization system also includes a high-pressure underlying gas kettle, a second constant temperature water bath device, a fourth pressure sensor, a third temperature sensor, a third sand control device, a fourth sand control device, a fifth sand control device, and a first quality monitoring unit, wherein: the second mining port is located at the lower part of the high-pressure underlying gas kettle; the second constant temperature water bath device is connected to the high-pressure underlying gas kettle, and is used to control the temperature inside the high-pressure underlying gas kettle; the fourth pressure sensor and the third temperature sensor are used to monitor the pressure and temperature inside the high-pressure underlying gas kettle, respectively; the quality monitoring unit is arranged below the high-pressure underlying gas kettle, and is used to record the quality inside the high-pressure underlying gas kettle in real time; the third sand control device is located between the upper part of the high-pressure underlying gas kettle and the combination valve, the fourth sand control device is arranged in the second mining port, and the fifth sand control device is arranged between the second control valve and the controllable pressure reduction mining system.
[0012] Preferably, the real-time quantitative system for gas-liquid production includes a gas-water separator, a gas container, a second quality monitoring unit, a fifth pressure sensor, a second temperature sensor, and a vent valve, wherein: the gas-water separator is connected to the controllable pressure reduction production system and the gas container (16) respectively; the second quality monitoring unit is arranged below the gas-water separator, and the second temperature sensor is connected to the gas-water separator; the vent valve and the fifth pressure sensor are both connected to the gas container.
[0013] Preferably, the controllable pressure reduction production system includes a back pressure valve and a control unit; the back pressure valve is respectively connected to the first control valve, the second control valve, the combination valve, the control unit and the gas-water separator, and the fifth sand prevention device is arranged between the second control valve and the back pressure valve; the control unit is respectively connected to the first quality monitoring unit and the second quality monitoring unit.
[0014] Preferably, it also includes a temperature and pressure data acquisition system, which is connected to the control unit, and the temperature and pressure data acquisition system is respectively connected to the first pressure sensor, the second pressure sensor, the third pressure sensor, the fourth pressure sensor, the fifth pressure sensor, the first temperature sensor, the second temperature sensor and the third temperature sensor.
[0015] Preferably, the water injection device has a flow meter, and the flow meter is connected to the control unit.
[0016] Preferably, the combination valve includes a first valve, a second valve, a third valve and a fourth valve, and the natural gas hydrate multi-gas combined production experimental device also includes a first four-way valve and a second four-way valve, wherein: the first valve, the second valve, the third valve and the fourth valve are respectively connected to the four ends of the second four-way valve, the first valve is connected to the third production port, the third valve is respectively connected to the water injection device and the gas injection device, the two ends of the first four-way valve are respectively connected to the second valve and the high-pressure underlying gas kettle, and the other two ends of the first four-way valve are respectively connected to the fourth pressure sensor and the third temperature sensor; the fourth valve is used for natural gas hydrate-underlying gas layer production.
[0017] Preferably, the first mass monitoring unit and the second mass monitoring unit are both electronic scales.
[0018] Preferably, the first temperature sensor is a multi-point temperature sensor, 18 thermocouples are arranged in the high-pressure reactor, and the 18 thermocouples are uniformly connected to the temperature and pressure data acquisition system through the first temperature sensor; the natural gas hydrate multi-gas combined production experimental device also includes a temperature control jacket, and the temperature control jacket is arranged on the outside of the high-pressure reactor.
[0019] The beneficial effects of the utility model include: the natural gas hydrate multi-gas co-production experimental device of the utility model can restore the natural gas hydrate-underlying gas reservoir occurrence system through experimental methods, can realize different multi-gas co-production processes, and perform quantitative monitoring of gas and water output. The utility model experimental device can simulate different mining processes, can be applied to the experimental research process of the depressurization rate of the key process of multi-gas co-production of the natural gas hydrate-underlying gas system depressurization method and the influence of the bottom hole flow pressure on the gas and water output behavior, and is suitable for the subsequent research on the control mechanism of the gas and water content of the underlying gas layer during the depressurization multi-gas co-production process. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic diagram of a natural gas hydrate multi-gas combined production experimental device in a preferred embodiment of the utility model.
[0021] Figure 2 yes Figure 1 Schematic diagram of the combination valve 21 in FIG.
[0022] Figure 3 is to use Figure 1 Flow chart of the experimental device for real-time quantitative monitoring of multi-gas production in the natural gas hydrate-underlying gas system.
[0023] The following are the descriptions of the reference numerals:
[0024] 1-first mining port, 2-second mining port, 3-third mining port, 4-temperature control jacket, 5-first four-way, 6-second four-way, P1-first pressure sensor, 7-first sand control device, 8-third sand control device, 9-fourth sand control device, 10-fifth sand control device, P2-second pressure sensor, T1-first temperature sensor, P3-third pressure sensor, T2-second temperature sensor, P5-fifth pressure sensor, 11-second control valve, 12-back pressure valve, 13-vent valve, 14-first constant temperature water bath device, 15-gas-water separation device, 16-gas container, 17-second sand control device, 18-temperature and pressure data acquisition system, 19-control unit, 20-second quality monitoring unit, 21-combination valve, 21-1-first valve, 21-2-second valve, 21-3-third valve, 21-4-fourth valve, P4-fourth pressure sensor, T3-third temperature sensor, 24-second constant temperature water bath device, 25-high-pressure natural gas hydrate reactor, 26-high-pressure underlying gas reactor, 27-first quality monitoring unit, 28-water injection device, 29-gas injection device, 30-first control valve. DETAILED DESCRIPTION
[0025] The present invention is further described below with reference to the accompanying drawings and in combination with preferred embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.
[0026] It should be noted that the directional terms such as left, right, up, down, top, and bottom in this embodiment are merely relative concepts or are based on the normal use status of the product, and should not be considered as restrictive.
[0027] Although the present invention uses the terms first, second, third, etc. to describe various elements and components, it should be understood that these components and components should not be limited by such terms. Such terms are only used to distinguish a certain element or component from another element or component, and they themselves do not represent any previous ordinal number of the element / component, nor do they represent the arrangement order of a certain element / component and another element / component, or the order in the manufacturing method. Therefore, without departing from the scope of the specific embodiments of the present invention, the first element or component discussed below can also be represented by the terms second element or component.
[0028] like Figure 1-2As shown, the specific implementation of the utility model provides a natural gas hydrate multi-gas co-production experimental device, which is used to simulate three different production processes: multi-gas co-production of natural gas hydrate layer, multi-gas co-production of underlying gas layer, and production between natural gas hydrate and underlying gas layer. It includes a high-pressure natural gas hydrate generation system, a high-pressure underlying gas system stabilization system, a gas-liquid output real-time quantitative system, a controllable pressure reduction production system, a water injection device 28, a gas injection device 29, a combination valve 21, a first control valve 30, and a second control valve 11; wherein: the high-pressure natural gas hydrate generation system is used to synthesize natural gas hydrate sediment samples, and has a first production port 1 (corresponding to multi-gas co-production of natural gas hydrate layer) at the top and a third production port 3 (corresponding to production between natural gas hydrate and underlying gas layer) at the bottom; the high-pressure underlying gas system stabilization system is used to prepare a simulated underlying gas layer A sample of sediment is arranged below the high-pressure natural gas hydrate generation system, and its upper part is connected to the third production port 3 of the high-pressure natural gas hydrate generation system through the combination valve 21, and the lower part has a second production port 2 (corresponding to the multi-gas production of the underlying gas layer); the controllable pressure reduction production system is used to regulate the bottom hole flow pressure in the three production processes, which are respectively: connected to the first production port 1 through the first control valve 30, connected to the second production port 2 through the second control valve 11, and connected to the third production port 3 through the combination valve 21; the gas-liquid output real-time quantitative system is connected to the controllable pressure reduction production system; the water injection device 28 and the gas injection device 29 are respectively connected to the high-pressure natural gas hydrate generation system and the high-pressure underlying gas system stabilization system through the combination valve 21.
[0029] The above-mentioned natural gas hydrate multi-gas co-production experimental device has the following working process:
[0030] 1. When the water injection device 28 and the gas injection device 29 are connected to the high-pressure natural gas hydrate generation system through the combination valve 21, the water injection device 28 and the gas injection device 29 are not connected to the high-pressure underlying gas system stabilization system through the combination valve 21, and the controllable pressure reduction production system is closed by the first control valve 30, the second control valve 11 and the combination valve 21, the natural gas hydrate sediment sample is prepared in the high-pressure natural gas hydrate generation system;
[0031] 2. When the water injection device 28 and the gas injection device 29 are connected to the high-pressure underlying gas system stabilization system through the combination valve 21, the water injection device 28 and the gas injection device 29 are not connected to the high-pressure natural gas hydrate generation system through the combination valve 21, and the controllable pressure reduction production system is closed by the first control valve 30, the second control valve 11 and the combination valve 21, the sample of the simulated underlying gas layer sediment is prepared in the high-pressure underlying gas system stabilization system;
[0032] 3. After the preparation of the natural gas hydrate sediment sample and the sample simulating the underlying gas sediment is completed, the water injection device 28 and the gas injection device 29 are closed through the combination valve 21, and three different mining processes can be carried out:
[0033] 3.1. Connect the controllable pressure reduction production system and the gas-liquid output real-time quantitative system to the first production port 1 through the first control valve 30, close the second control valve 11, connect the third production port 3 of the high-pressure natural gas hydrate generation system to the high-pressure underlying gas system stabilization system through the combination valve 21, and close the natural gas hydrate-underlying gas layer production function corresponding to the third production port 3 through the combination valve 21, and simulate the multi-gas production operation of the natural gas hydrate layer through the first production port 1;
[0034] 3.2. The controllable pressure reduction production system and the gas-liquid output real-time quantitative system are connected to the third production port 3 through the combination valve 21, the first control valve 30 and the second control valve 11 are closed, and the third production port 3 of the high-pressure natural gas hydrate generation system is connected to the high-pressure underlying gas system stabilization system through the combination valve 21, and the operation of simulating natural gas hydrate-underlying gas layer production is performed through the third production port 3;
[0035] 3.3. Connect the controllable pressure reduction production system and the gas-liquid output real-time quantitative system to the second production port 2 through the second control valve 11, close the first control valve 30, connect the third production port 3 of the high-pressure natural gas hydrate generation system and the high-pressure underlying gas system stabilization system through the combination valve 21, and close the natural gas hydrate-underlying gas layer production function corresponding to the third production port 3 through the combination valve 21, and simulate the operation of multi-gas combined production in the underlying gas layer through the second production port 2.
[0036] In a preferred embodiment, the high-pressure natural gas hydrate generation system further includes a first constant temperature water bath device 14, a first pressure sensor P1, a second pressure sensor P2, a third pressure sensor P3, a first temperature sensor T1, a high-pressure reactor 25, a first sand control device 7, and a second sand control device 17; wherein: the high-pressure reactor 25 is a preparation device for natural gas hydrate sediment samples, the first mining port 1 is located at the upper part of the high-pressure reactor 25, and the third mining port 3 is located at the lower part of the high-pressure reactor 25. The first constant temperature water bath device 14 is connected to the high-pressure reactor 25 for controlling the temperature inside the high-pressure reactor 25. For example, the high-pressure reactor 25 is connected to the first constant temperature water bath device 14 through a water cooling pipe, and a water cooling liquid is pumped into the water cooling pipe through a circulating pump (not shown) to control the temperature inside the high-pressure reactor 25. More preferably, a temperature control jacket 4 is also provided on the outside of the high-pressure reactor 25. To better control the temperature inside the high-pressure reactor 25; the first pressure sensor P1 and the second pressure sensor P2 are located at the top of the high-pressure reactor 25, and the third pressure sensor P3 is located at the bottom of the high-pressure reactor 25, which are used to monitor the pressure evolution of the natural gas hydrate sediment reservoir during the multi-gas production of natural gas hydrates; the first sand control device 7 is arranged between the first control valve 30 and the first production port 1, and the second sand control device 17 is arranged in the third production port 3. The first temperature sensor T1 is used to monitor the changes in the internal temperature field of the high-pressure reactor. More preferably, the first temperature sensor T1 is a multi-point temperature sensor. 18 thermocouples are configured in the high-pressure reactor 25, and the 18 thermocouples are uniformly connected to the temperature and pressure data acquisition system 18 through the first temperature sensor T1 to monitor the changes in the internal temperature field of the high-pressure reactor.
[0037] In a preferred embodiment, the high-pressure gas system stabilization system also includes a high-pressure gas kettle 26, a second constant temperature water bath device 24, a fourth pressure sensor P4, a third temperature sensor T3, a third sand control device 8, a fourth sand control device 9, a fifth sand control device 10, and a first quality monitoring unit 27 (preferably a large-range and high-precision electronic scale in this example), wherein: the second mining port 2 is located at the lower part of the high-pressure gas kettle 26, the high-pressure gas kettle 26 can be connected to the high-pressure reactor 25 through a pressure-resistant pipe, the second constant temperature water bath device 24 is connected to the high-pressure gas kettle 26, and is used to control the temperature of the interior of the high-pressure gas kettle 26; the fourth pressure sensor P4 and the third temperature sensor T3 are respectively used for monitoring the internal pressure and temperature of the high-pressure underlying gas kettle 26; the first quality monitoring unit 27 is arranged below the high-pressure underlying gas kettle 26, for real-time recording of the mass changes in the high-pressure underlying gas kettle 26, and then real-time quantification of the internal water volume, to provide data support for the quantification of the gas saturation of the underlying gas system; the third sand control device 8 is located between the upper part of the high-pressure underlying gas kettle 26 and the combination valve 21, and the fourth sand control device 9 is arranged in the second mining port 2; the fifth sand control device 10 is arranged between the second control valve 11 and the controllable pressure reduction mining system, and the second control valve 11 is used as the master control valve of the multi-gas combined production process of the underlying gas layer, and is used to control the start time of the multi-gas combined production of the underlying gas layer.
[0038] In a preferred embodiment, the gas-liquid production real-time quantitative system includes a gas-water separator 15, a gas container 16, a second quality monitoring unit 20 (preferably an electronic scale in this example), a fifth pressure sensor P5 and a second temperature sensor T2, and a vent valve 13, wherein: the gas-water separator 15 is connected to the controllable pressure reduction production system and is connected to the gas container 16 through a pipeline; the second quality monitoring unit 20 is arranged below the gas-water separator 15 to monitor the water production during the production process; the second temperature sensor T2 is connected to the gas-water separator 15, so The vent valve 13 and the fifth pressure sensor P5 are both connected to the gas container 16. The vent valve 13 is used to discharge and vent the gas in the gas container 16 after the experiment is over to prepare for the next experiment. Since the gas-water separator 15 is connected to the gas container 16, the pressure change in the gas container 16 has almost no effect on the temperature in the gas container 16. Therefore, it can be considered that the temperature of the gas-water separator 15 is consistent with that of the gas container 16, so that the second temperature sensor T2 and the fifth pressure sensor P5 can respectively monitor the temperature and pressure data of the gas container 16 for real-time calculation during the mining process.
[0039] In a preferred embodiment, the controllable pressure reduction mining system includes a backpressure valve 12 and a control unit 19 (in this example, the control unit is, for example, a computer equipped with control software); the backpressure valve 12 is respectively connected to the first control valve 30, the second control valve 11, the combination valve 21, the control unit 19 and the gas-water separator 15; the fifth sand prevention device 10 is arranged between the second control valve 11 and the backpressure valve 12 to prevent sand from entering the backpressure valve 12 to avoid failure of the pressure control function of the backpressure valve 12; the control unit 19 is respectively connected to the first quality monitoring unit 27 and the second quality monitoring unit 20 to record the quality data monitored by the first quality monitoring unit 27 and the second quality monitoring unit 20 in real time. The back pressure valve 12 cooperates with the second pressure sensor P2 to adjust the bottom hole flow pressure in three mining processes, and realizes functions such as uniform pressure reduction, segmented pressure reduction and constant pressure mining. Its working principle is: the pressure reduction rate and the stable mining pressure V1 are set in the control unit 19, and the second pressure sensor P2 transmits the pressure value V2 to the control unit 19 in real time. If there is a deviation between V1 and V2, the back pressure valve 12 switch is controlled to adjust the pressure V2 in the high-pressure reactor 25 to the set value V1.
[0040] In a preferred embodiment, the natural gas hydrate multi-gas co-production experimental device also includes a temperature and pressure data acquisition system 18, which is connected to the control unit 19, and the temperature and pressure data acquisition system 18 is respectively connected to the first pressure sensor P1, the second pressure sensor P2, the third pressure sensor P3, the fourth pressure sensor P4, the fifth pressure sensor P5, the first temperature sensor T1, the second temperature sensor T2 and the third temperature sensor T3 to collect the temperature and pressure data of these sensors and transmit them to the control unit 19.
[0041] In a preferred embodiment, the water injection device 28 has a flow meter 22, and the flow meter 22 is connected to the control unit 19. The temperature, pressure, flow, and quality signals can be calibrated, monitored, and recorded through the control unit 19, providing technical support for the study of the gas and water quantification of the high-pressure reactor 25 and the high-pressure underlying gas reactor 26, as well as the gas and water output control mechanism during the mining process.
[0042] In a preferred embodiment, the combination valve 21 includes a first valve 21-1, a second valve 21-2, a third valve 21-3 and a fourth valve 21-4, and the natural gas hydrate multi-gas combined production experimental device also includes a first four-way valve 5 and a second four-way valve 6, wherein: the first valve 21-1, the second valve 21-2, the third valve 21-3 and the fourth valve 21-4 are respectively connected to the four ends of the second four-way valve 6, the first valve 21-1 is connected to the third production port 3, the third valve 21-3 is respectively connected to the water injection device 28 and the gas injection device 29, the two ends of the first four-way valve 5 are respectively connected to the second valve 21-2 and the high-pressure underlying gas kettle 26, and the other two ends of the first four-way valve 5 are respectively connected to the fourth pressure sensor P4 and the third temperature sensor T3; the fourth valve 21-4 is used for natural gas hydrate-underlying gas layer production. When the first valve 21-1 and the third valve 21-3 are opened and the second valve 21-2, the fourth valve 21-4, and the first control valve 30 are closed, high-pressure water can be injected from the water injection device 28 into the high-pressure reactor 25, and gas (methane) can be injected from the gas injection device 29 into the high-pressure reactor 25 to achieve the synthesis of natural gas hydrate sediment samples with different saturations. When the second valve 21-2 and the third valve 21-3 are opened and the first valve 21-1, the fourth valve 21-4, and the first control valve 30 are closed, high-pressure water can be injected from the water injection device 28 into the high-pressure underlying gas reactor 26, and gas (methane) can be injected from the gas injection device 29 into the high-pressure underlying gas reactor 26 to prepare samples simulating underlying gas layer sediments. When the first control valve 30, the first valve 21-1, and the second valve 21-2 are opened, and the second control valve 11, the third valve 21-3, and the fourth valve 21-4 are closed, the controllable pressure reduction production system can be connected to the first control valve 30 to realize multi-gas co-production in the natural gas hydrate layer. When the fourth valve 21-4 is opened and the first control valve 30, the second control valve 11, the first valve 21-1, the second valve 21-2, and the third valve 21-3 are closed, the controllable pressure reduction production system can be connected to the fourth valve 21-4 to realize the production between the natural gas hydrate and the underlying gas layer, that is, the production operation is performed between the natural gas hydrate layer and the underlying gas layer. When the second control valve 11, the first valve 21-1, and the second valve 21-2 are opened, and the first control valve 30, the third valve 21-3, and the fourth valve 21-4 are closed, the controllable pressure reduction production system can be connected to the second control valve 11 to realize multi-gas co-production in the underlying gas layer.
[0043] The natural gas hydrate multi-gas co-production experimental device of the utility model embodiment can be applied to the experimental study of the depressurization rate of the key process of multi-gas co-production of the natural gas hydrate-underlying gas system depressurization method and the influence of the bottom hole flow pressure on the gas and water production behavior, and is suitable for the follow-up study of the control mechanism of the gas and water content of the underlying gas layer during the depressurization multi-gas co-production process. This device has established a set of real-time monitoring devices for the construction of the natural gas hydrate-underlying gas system and the gas and water production and gas and water evolution behavior of the underlying gas system during the depressurization method multi-gas co-production process, which can simulate different mining processes.
[0044] In the natural gas hydrate multi-gas combined production experimental device of the preferred embodiment of the utility model, the first quality monitoring unit 27 installed below the high-pressure underlying gas kettle 26 can record its internal mass changes in real time. At the same time, in combination with the volume conservation calculation method, it can realize quantitative monitoring and evaluation of the natural gas hydrate-underlying gas system in different pressure reduction production schemes, different pressure reduction stages and constant pressure production stages: 1. The saturation of each phase in the natural gas hydrate-containing sediments and the underlying gas-containing sediments, and 2. The total gas and water output of multi-gas combined production by the pressure reduction method, and then obtain 3. The influence of underlying gas sediments with different water saturations on the gas and water output behavior of multi-gas combined production by the pressure reduction method.
[0045] The three mining ports provided in the gas hydrate multi-gas co-production experimental device of the utility model are respectively suitable for simulating three different mining processes: multi-gas co-production of the gas hydrate layer (first mining port 1), multi-gas co-production of the underlying gas layer (second mining port 2), and mining between the gas hydrate and the underlying gas layer (third mining port 3). These three mining processes correspond to different perforation drilling and depressurization mining schemes in the mining process of the gas hydrate-underlying gas system reservoir in actual engineering. Specifically:
[0046] (1) Multi-gas production in natural gas hydrate layer (first production port 1) is to set the production port in the natural gas hydrate layer for multi-gas production. This process simulates the multi-gas production process of drilling into the natural gas hydrate layer during actual production. The specific operation is to connect the controllable pressure reduction production system and the gas-liquid output real-time quantitative system to the first control valve 30 controlling the first production port 1 through a pipeline after the preparation of the natural gas hydrate sediment sample and the simulated underlying gas sediment sample is completed, close the third valve 21-3, the fourth valve 21-4, and the second control valve 11, open the first valve 21-1 and the second valve 21-2 to connect the high-pressure reactor 25 and the high-pressure underlying gas reactor 26, and open the first control valve 30 for production;
[0047] (2) Exploitation between natural gas hydrate and underlying gas layer (third exploitation port 3) is to set the exploitation port between the natural gas hydrate layer and the underlying gas layer for multi-gas combined exploitation. This process simulates the multi-gas combined exploitation process in which the well is drilled to the junction of the natural gas hydrate layer and the underlying gas layer during the actual exploitation process. The specific operation is that after the preparation of the natural gas hydrate sediment sample and the simulated underlying gas sediment sample is completed, the controllable pressure reduction exploitation system and the gas-liquid output real-time quantitative system are connected to the fourth valve 21-4 in the combination valve 21 controlling the third exploitation port 3 through a pipeline, the third valve 21-3, the first control valve 30, and the second control valve 11 are closed, the first valve 21-1 and the second valve 21-2 are opened to connect the high-pressure reactor 25 and the high-pressure underlying gas reactor 26, and the fourth valve 21-4 is opened for exploitation;
[0048] (3) Multi-gas production in the underlying gas layer (second production port 2) is to set the production port in the underlying gas layer for multi-gas production. This process simulates the multi-gas production process of drilling into the underlying gas layer during the actual production process. The specific operation is to connect the controllable pressure reduction production system and the gas-liquid output real-time quantitative system to the second control valve 11 controlling the second production port 2 through a pipeline after the preparation of the natural gas hydrate sediment sample and the underlying gas sediment sample is completed, close the third valve 21-3, the fourth valve 21-4, and the first control valve 30, open the first valve 21-1 and the second valve 21-2 to connect the high-pressure reactor 25 and the high-pressure underlying gas reactor 26, and open the second control valve 11 for production.
[0049] This experimental device can realize the experimental simulation of the natural gas hydrate-underlying gas system and the gas-water hydrate three-phase layer-underlying gas layer in the actual reservoir, expand the understanding of the main controlling factors of the gas and water production behavior in the multi-gas commingled production process of the natural gas hydrate-underlying gas system, and provide guidance for the selection and optimization of pressure reduction schemes and the optimization of production increase schemes in future natural gas hydrate experiments and reservoir-scale field multi-gas commingled production tests.
[0050] like Figure 3 As shown, when using the experimental device of the utility model to carry out real-time quantitative monitoring of multi-gas co-production in a natural gas hydrate-underlying gas system, the following steps are included:
[0051] Implementation step S1: Preparation of gas hydrate sediment samples. According to the target reservoir sediment type, temperature and pressure conditions, and the three-phase saturation of gas, water, and hydrate, the gas injection volume and water injection volume are calculated to synthesize a sediment sample containing gas hydrates of a specified saturation in the high-pressure reactor 25. The experimental device can synthesize a gas hydrate sediment sample containing an excess water system by a single gas injection and multi-step water injection, and synthesize a gas hydrate sample containing a three-phase system by a gas injection-multi-step water injection-secondary gas injection method, which respectively correspond to the gas hydrate layer and the three-phase layer in the actual reservoir (e.g., the Shenhu Sea area of the South China Sea).
[0052] Implementation step S2: Preparation of samples simulating the underlying gas layer sediments. According to the lithology of the underlying gas-containing sediments in the target reservoir and the gas-water two-phase saturation, the gas injection volume and the water injection volume are calculated. At the same time, according to the methane phase equilibrium curve, the temperature and pressure conditions are controlled by the independent water bath (second constant temperature water bath device 24) of the high-pressure underlying gas kettle 26 and the gas and water injection volume to ensure that natural gas hydrates cannot be generated in the high-pressure underlying gas kettle 26, thereby restoring the gas-water two-phase occurrence environment of the underlying gas layer in the actual formation.
[0053] Experimental step S3: Conduct multi-gas co-production by controlled depressurization. Taking multi-gas co-production of the underlying gas layer as an example, after the temperature and pressure of the natural gas hydrate sediment system in the high-pressure reactor 25 are stabilized, the first valve 21-1 and the second valve 21-2 are opened (the third valve 21-3 and the fourth valve 21-4 are in a closed state) to connect the high-pressure reactor 25 and the high-pressure underlying gas reactor 26, and the natural gas hydrate depressurization multi-gas co-production experiment is carried out according to the preset depressurization scheme (depressurization rate, bottom hole flow pressure). Three different multi-gas co-production processes can be carried out according to demand, namely, multi-gas co-production of the natural gas hydrate layer, production between natural gas hydrate and the underlying gas layer, and multi-gas co-production of the underlying gas layer. Production is carried out through the back pressure valve 12 according to the preset depressurization scheme. During this production period, the first quality monitoring unit 27 can record the quality change of the lower high-pressure underlying gas reactor 26 in real time, and then obtain the amount of water that migrates from the high-pressure reactor 25 to the high-pressure underlying gas reactor 26 and is retained therein.
[0054] Experimental step S4: data processing. The fluid output data (including gas production and water production) that affect the sedimentation of natural gas hydrate sediments during the depressurization process are recorded by the second quality monitoring unit 20 installed at the bottom of the gas-water separator 15 and the gas container 16 connected to the gas-water separator 15; the pressure and temperature data of the gas container 16 are collected by the temperature and pressure data acquisition system 18 through the second temperature sensor T2 and the fifth pressure sensor P5 and recorded in the control unit 19, and then the gas-water production evolution curve is calculated and compared with the temperature and pressure curve and the sedimentation curve to obtain the sedimentation mechanism of natural gas hydrate sediments during the depressurization process.
[0055] Existing laboratory indoor multi-gas production experiments are affected by the site and scale, and cannot restore the spatial distribution of the natural gas hydrate layer above and the underlying gas layer below, and thus cannot consider the influence of gravity on fluid migration during the multi-gas production process, and cannot realize different multi-gas production processes such as multi-gas production of the natural gas hydrate layer, production between natural gas hydrate and the underlying gas layer, and multi-gas production of the underlying gas layer. In addition, the existing experimental device cannot quantify the change in water content in the underlying gas kettle. To this end, the utility model proposes a natural gas hydrate multi-gas production experimental device, which has solved the above problems and realized the research on different multi-gas production processes in the natural gas hydrate-underlying gas layer system and the natural gas hydrate-three-phase layer system.
[0056] The preferred embodiment of the utility model has the following characteristics:
[0057] 1. The high-pressure natural gas hydrate reactor 25 and the high-pressure underlying gas reactor 26 spatially restore the distribution characteristics of the actual reservoir, in which the natural gas hydrate layer is on the top and the underlying gas layer is on the bottom, and fully consider the influence of gravity on fluid migration. The high-pressure natural gas hydrate reactor 25 and the high-pressure underlying gas reactor 26 can be controlled in temperature and pressure respectively, thereby avoiding the formation of natural gas hydrate in the high-pressure underlying gas reactor 26.
[0058] 2. The first quality monitoring unit 27 is used to monitor the quality change of the high-pressure gas kettle 26 in real time to obtain the change of its internal water content, thereby realizing the quantitative monitoring of the saturation change of each phase in the high-pressure gas kettle 26 during the multi-gas production process of natural gas hydrates.
[0059] 3. The temperature and pressure conditions of the high-pressure natural gas hydrate reactor 25 and the high-pressure underlying gas reactor 26 are controlled separately, and on this basis, they can be connected to realize the multi-gas commingled production process, that is, through the combination of different production ports and combination valves, different multi-gas commingled production processes such as multi-gas commingled production of the natural gas hydrate layer, production between the natural gas hydrate and the underlying gas layer, and multi-gas commingled production of the underlying gas layer can be realized.
[0060] 4. The real-time quantitative measurement system for gas and liquid output can quantitatively monitor and record the overall gas and water production of the system in real time.
[0061] The experimental device in the preferred embodiment of the utility model is a real-time quantitative device that can monitor the sedimentation of natural gas hydrates in different depth intervals under high pressure conditions, and can be applied to technical fields such as natural gas hydrate exploitation, hydrate-based carbon dioxide storage, and regional sedimentation assessment and process optimization in unconventional gas reservoirs such as coalbed methane.
[0062] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For technicians in the technical field to which the present invention belongs, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.
Claims
1. A natural gas hydrate multi-gas co-production experimental device, characterized in that: The invention is used to simulate three different production processes, namely, multi-gas co-production in a natural gas hydrate layer, multi-gas co-production in an underlying gas layer, and production between a natural gas hydrate and an underlying gas layer, and comprises a high-pressure natural gas hydrate generation system, a high-pressure underlying gas system stabilization system, a gas-liquid output real-time quantitative system, a controllable pressure reduction production system, a water injection device (28), a gas injection device (29), a combination valve (21), a first control valve (30), and a second control valve (11); wherein: The high-pressure natural gas hydrate generation system is used for synthesizing natural gas hydrate sediment samples, and has a first mining port (1) at the top and a third mining port (3) at the bottom; The high-pressure underlying gas hydrate stabilization system is used to prepare samples simulating underlying gas layer sediments, and is arranged below the high-pressure natural gas hydrate generation system, with its upper portion connected to the third production port (3) of the high-pressure natural gas hydrate generation system through the combination valve (21), and its lower portion having a second production port (2); The controllable pressure reduction production system is used to control the bottom hole flow pressures of the three production processes, and is respectively connected to the first production port (1) through the first control valve (30), connected to the second production port (2) through the second control valve (11), and connected to the third production port (3) through the combination valve (21); The gas-liquid production real-time quantitative system is connected to the controllable pressure reduction production system; The water injection device (28) and the gas injection device (29) are respectively connected to the high-pressure natural gas hydrate generation system and the high-pressure underlying gas system stabilization system through the combined valve (21).
2. The natural gas hydrate multi-gas co-production experimental device according to claim 1, characterized in that: The high-pressure natural gas hydrate generation system further comprises a first constant temperature water bath device (14), a first pressure sensor (P1), a second pressure sensor (P2), a third pressure sensor (P3), a first temperature sensor (T1), a high-pressure reactor (25), a first sand control device (7), and a second sand control device (17); wherein: The first mining port (1) is located at the upper part of the high-pressure reactor (25), and the third mining port (3) is located at the lower part of the high-pressure reactor (25); The first constant temperature water bath device (14) is connected to the high pressure reactor (25) and is used to control the temperature inside the high pressure reactor (25); The first pressure sensor (P1) and the second pressure sensor (P2) are located at the top of the high-pressure reactor (25), and the third pressure sensor (P3) is located at the bottom of the high-pressure reactor (25); the first sand prevention device (7) is arranged between the first control valve (30) and the first mining port (1), and the second sand prevention device (17) is arranged in the third mining port (3); the first temperature sensor (T1) is used to monitor the internal temperature field changes of the high-pressure reactor (25).
3. The natural gas hydrate multi-gas co-production experimental device according to claim 2, characterized in that: The high-pressure subsurface gas system stabilization system further comprises a high-pressure subsurface gas kettle (26), a second constant temperature water bath device (24), a fourth pressure sensor (P4), a third temperature sensor (T3), a third sand control device (8), a fourth sand control device (9), a fifth sand control device (10), and a first quality monitoring unit (27), wherein: The second mining port (2) is located at the lower part of the high-pressure gas kettle (26); The second constant temperature water bath device (24) is connected to the high pressure gas kettle (26) and is used to control the temperature inside the high pressure gas kettle (26); The fourth pressure sensor (P4) and the third temperature sensor (T3) are used to monitor the pressure and temperature inside the high-pressure gas kettle (26) respectively; The quality monitoring unit (27) is arranged below the high-pressure gas kettle (26) and is used to record the quality of the high-pressure gas kettle (26) in real time; The third sand control device (8) is located between the upper part of the high-pressure underlying gas kettle (26) and the combination valve (21), the fourth sand control device (9) is arranged in the second mining port (2), and the fifth sand control device (10) is arranged between the second control valve (11) and the controllable pressure reduction mining system.
4. The natural gas hydrate multi-gas co-production experimental device according to claim 3, characterized in that: The gas-liquid production real-time quantitative system comprises a gas-water separator (15), a gas container (16), a second quality monitoring unit (20), a fifth pressure sensor (P5) and a second temperature sensor (T2), and a vent valve (13), wherein: The gas-water separator (15) is respectively connected to the controllable pressure reduction production system and the gas container (16); The second quality monitoring unit (20) is arranged below the gas-water separator (15), and the second temperature sensor (T2) is connected to the gas-water separator (15); The vent valve (13) and the fifth pressure sensor (P5) are both connected to the gas container (16).
5. The natural gas hydrate multi-gas co-production experimental device according to claim 4, characterized in that: The controllable pressure reduction mining system comprises a back pressure valve (12) and a control unit (19); The back pressure valve (12) is respectively connected to the first control valve (30), the second control valve (11), the combination valve (21), the control unit (19) and the gas-water separator (15); the fifth sand control device (10) is arranged between the second control valve (11) and the back pressure valve (12); The control unit (19) is connected to the first quality monitoring unit (27) and the second quality monitoring unit (20) respectively.
6. The natural gas hydrate multi-gas co-production experimental device according to claim 5, characterized in that: The invention also includes a temperature and pressure data acquisition system (18), wherein the temperature and pressure data acquisition system (18) is connected to the control unit (19), and the temperature and pressure data acquisition system (18) is respectively connected to the first pressure sensor (P1), the second pressure sensor (P2), the third pressure sensor (P3), the fourth pressure sensor (P4), the fifth pressure sensor (P5), the first temperature sensor (T1), the second temperature sensor (T2) and the third temperature sensor (T3).
7. The natural gas hydrate multi-gas co-production experimental device according to claim 6, characterized in that: The water injection device (28) has a flow meter (22), and the flow meter (22) is connected to the control unit (19).
8. The natural gas hydrate multi-gas co-production experimental device according to claim 3, characterized in that: The combined valve (21) comprises a first valve (21-1), a second valve (21-2), a third valve (21-3) and a fourth valve (21-4), and the natural gas hydrate multi-gas combined production experimental device further comprises a first four-way valve (5) and a second four-way valve (6), wherein: The first valve (21-1), the second valve (21-2), the third valve (21-3) and the fourth valve (21-4) are respectively connected to the four ends of the second four-way valve (6); the first valve (21-1) is connected to the third exploitation port (3); the third valve (21-3) is respectively connected to the water injection device (28) and the gas injection device (29); the two ends of the first four-way valve (5) are respectively connected to the second valve (21-2) and the high-pressure underlying gas kettle (26); the other two ends of the first four-way valve (5) are respectively connected to the fourth pressure sensor (P4) and the third temperature sensor (T3); the fourth valve (21-4) is used for exploitation between natural gas hydrate and underlying gas layer.
9. The natural gas hydrate multi-gas co-production experimental device according to claim 7, characterized in that: The first quality monitoring unit (27) and the second quality monitoring unit (20) are both electronic scales.
10. The natural gas hydrate multi-gas co-production experimental device according to claim 7, characterized in that: The first temperature sensor (T1) is a multi-point temperature sensor. 18 thermocouples are arranged in the high-pressure reactor (25). The 18 thermocouples are connected to the temperature and pressure data acquisition system (18) through the first temperature sensor (T1). The natural gas hydrate multi-gas production experimental device also includes a temperature control jacket (4), and the temperature control jacket (4) is arranged on the outside of the high-pressure reactor (25).