Natural gas hydrate underground gas-liquid separation and combustion heating integrated device

Abstract

The invention relates to an underground tool for natural gas hydrate development, in particular to a natural gas hydrate underground gas-liquid separation and combustion heating integrated device which comprises an underground natural gas combustion heating device and a gas-liquid separation device. Mainly comprises a shell nozzle, a shell body, a small nozzle, a small plug, a central pipe, a pressure-bearing pipe, a gland, a limiting block, a bent pipe, an igniter, a gasket, an upper joint, an inlet ring, a connecting pipe, a spiral body, a barrel body, a lower joint and a rubber plug, the underground natural gas combustion heating device and the gas-liquid separation device are connected through a bore log to achieve integration. Natural gas generated by decomposition of natural gas hydrates is directly combusted underground, the stratum is heated to promote decomposition of the natural gas hydrates, and the recovery rate of the natural gas hydrates is increased. And the gas-liquid separation device and the combustion heating device are integrally designed, so that the complexity of underground equipment is reduced, and the reliability and operability of the device are improved.

Description

Technical Field

[0001] The invention patent relates to a downhole tool for natural gas hydrate development, in particular to a natural gas hydrate downhole gas-liquid separation and combustion heating integrated device. Technical Background

[0002] Natural gas hydrate is an ice-like solid formed by natural gas and water under low temperature and high pressure. It is widely distributed in deep-sea sediments and permafrost areas. As a potential energy source, its reserves are huge, but it is difficult to mine. The depressurization method is currently a common method for natural gas hydrate mining, but depressurization mining faces the problem of insufficient reservoir sensible heat and environmental heat transfer, which triggers the reverse reaction of natural gas hydrate regeneration and the production of ice, ultimately leading to discontinuous gas production and low decomposition rate of natural gas hydrates. Energy supplement methods such as injecting hot water or steam, downhole electric heating, and microwave heating as an enhanced mining measure can increase the reservoir temperature, break the phase equilibrium conditions of natural gas hydrates, and promote the decomposition of natural gas hydrates. It is very effective in making up for the shortcomings of low production capacity of natural gas hydrate natural depressurization mining, but it requires additional energy to be supplemented from the ground to the formation, and there are problems such as complex process equipment and low energy utilization. Directly burning the natural gas produced by the decomposition of natural gas hydrates underground to heat the natural gas hydrate reservoir and promote the decomposition of natural gas hydrates is a new solution. However, on the one hand, the natural gas produced by the decomposition of natural gas hydrates contains water vapor, which causes the natural gas to be too humid. On the other hand, the decomposition rate of natural gas hydrates is slow, resulting in a low natural gas flow rate. Therefore, the natural gas produced by the decomposition of natural gas hydrates cannot be directly burned. It is urgent to design a device that can directly burn the natural gas produced by the decomposition of natural gas hydrates underground to solve the problem of high humidity and low flow rate of the natural gas produced by the decomposition of natural gas hydrates, thereby heating the natural gas hydrate reservoir, promoting the decomposition of natural gas hydrates, and thus improving the recovery rate of natural gas hydrates. Summary of the invention

[0003] The present invention aims to overcome the problem of high humidity and low flow rate of natural gas produced by decomposition of natural gas hydrates. The proposed natural gas hydrate underground gas-liquid separation and combustion heating integrated device can heat the natural gas hydrate reservoir and promote the decomposition of natural gas hydrates by burning the natural gas produced by decomposition of natural gas hydrates underground, thereby improving the recovery rate of natural gas hydrates. The technical scheme adopted is as follows:

[0004] The natural gas hydrate downhole gas-liquid separation and combustion heating integrated device includes a downhole natural gas combustion heating device and a gas-liquid separation device, and is mainly composed of an outer shell nozzle, an outer shell shell, a small nozzle, a small plug, a center pipe, a pressure pipe, a pressure cover, a limit block, a bend, an igniter, a gasket, an upper joint, an inlet ring, a connecting pipe, a spiral body, a cylinder, a lower joint, and a rubber plug.

[0005] In the downhole natural gas combustion and heating device, the small nozzle and the center tube are coaxially fixedly connected, so that the natural gas is discharged from the small nozzle after being transported through the center tube. The limit block is connected to the pressure tube and the igniter through the hole axis, and the igniter is fixed on the pressure tube. The center tube is connected to the inside of the pressure tube through the hole column between the small plug, and the center tube is fixed to the inside of the pressure tube. The outer shell, the outer shell nozzle, and the pressure cover are connected by threads to protect the internal pipeline and form a combustion chamber at the same time. The elbow is connected to the pressure tube, and the mixed gas is injected into the combustion chamber through the elbow. The elbows are fixed by rubber plugs.

[0006] In the gas-liquid separation device, the upper joint, the inlet ring, the cylinder and the lower joint are connected by a hole column to form an external shell, the upper joint is connected to the connecting pipe by the hole column and fixed inside the shell, and the spiral body and the connecting pipe are connected by a thread. The spiral body and the connecting pipe constitute a spiral device, which realizes the separation of natural gas and water vapor, realizes the drying process of natural gas, and ensures the combustion of natural gas.

[0007] The underground natural gas combustion heating device and the gas-liquid separation device are integrated through a hole column connection.

[0008] The natural gas hydrate that enters the gas-liquid separation device through the inlet ring is separated by the spiral device. The liquid flows down along the spiral body in strands, and the gas is discharged upward from the spiral body tube. Part of it is discharged from the small nozzle through the central pipe, and part of it is passed into the combustion chamber through the curved pipe for combustion.

[0009] The present invention designs an integrated device for underground gas-liquid separation and combustion heating of natural gas hydrates. The gas-liquid separation device separates natural gas and water vapor through a spiral device, realizes natural gas drying, and ensures the combustion of natural gas. The underground natural gas combustion and heating device can further promote the decomposition of natural gas hydrates by burning the natural gas generated by the decomposition of underground natural gas hydrates and heating the formation. The specific working process is as follows:

[0010] The natural gas produced by the decomposition of natural gas hydrates cannot be burned directly. The first reason is that it contains water vapor and the second is that the flow rate is insufficient. Therefore, the gas-liquid separation is first performed through a gas-liquid separation device. The gas-liquid two-phase flow passes through the inlet ring and axially enters the spiral separation device. After passing through the guide blades, the two-phase flow changes from axial motion to spiral rotational motion. Among them, the centrifugal force on the droplets is large, and the two phases are separated. The droplets are captured by the outer wall of the flow channel. After the aggregation of the droplets and the action of gravity and airflow, the liquid flows down along the spiral body in strands, and the gas is discharged upward from the spiral tube, completing the gas-liquid separation process.

[0011] The natural gas that has completed the separation of gas and liquid continues to enter the downhole natural gas combustion and heating device from the gas-liquid separation device. Part of the natural gas passes through the downhole natural gas combustion and heating device through the central pipe and is sent to the ground through the downhole pipe string; the other part of the natural gas is injected into the combustion chamber between the central pipe and the pressure pipe through the curved pipe, and is transported from the combustion chamber to the combustion port and ejected from the combustion port. The ground controls the downhole igniter through cables to make the mixed gas burn, thereby heating the reservoir.

[0012] The present invention has the following advantages: the device separates natural gas and water vapor through a spiral device, realizes natural gas drying, and ensures the combustion of natural gas; on the other hand, the natural gas flow rate is increased through the spiral speed increase and the small diameter speed increase, further promoting the combustion of natural gas. By directly burning the natural gas produced by the decomposition of natural gas hydrates underground, heating the formation further promotes the decomposition of natural gas hydrates, thereby improving the recovery rate of natural gas hydrates. The integrated design of the gas-liquid separation device and the combustion and heating device reduces the complexity of underground equipment and improves the reliability and operability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 : Overall diagram of the natural gas hydrate downhole gas-liquid separation and combustion heating integrated device;

[0014] Figure 2 : Structural diagram of gas-liquid separation device;

[0015] Figure 3 : Structural diagram of underground natural gas combustion heating device.

[0016] Explanation of symbols:

[0017] 1. Upper joint; 2. Connecting pipe; 3. Inlet ring; 4. Helix; 5. Cylinder; 6. Lower joint; 7. Small nozzle; 8. Shell nozzle; 9. Stopper; 10. Center pipe; 11. Pressure pipe; 12. Shell; 13. Stopper; 14. Small plug; 15. Bend pipe; 16. Gland; 17. Ignition device; 18. Gasket; 19. Downhole natural gas combustion and heating device; 20. Gas-liquid separation device; DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and examples:

[0019] like Figure 1-Figure 3As shown, the natural gas hydrate underground gas-liquid separation and combustion heating integrated device designed by the present invention includes a gas-liquid separation device, an underground natural gas combustion heating device and a rubber ring. It mainly consists of an upper joint 1, a connecting pipe 2, an inlet ring 3, a spiral body 4, a cylinder 5, a lower joint 6, a small nozzle 7, an outer shell nozzle 8, a limit block 9, a central pipe 10, a pressure-bearing pipe 11, an outer shell 12, a limit block 13, a small plug 14, a bend 15, a gland 16, an igniter 17, and a gasket 18.

[0020] In the downhole natural gas combustion and heating device, the small nozzle 6 is coaxially fixedly connected with the central tube 10, so that the natural gas is discharged from the small nozzle 6 after being transported through the central tube 10. The limit block 9 is connected with the pressure pipe 11 and the igniter 17 through the hole axis, and the igniter 17 is fixed on the pressure pipe 11. The central tube 10 is connected with the small plug 14 through the hole column, and the central tube 10 is fixed inside the pressure pipe 11. The outer shell 12, the outer shell nozzle 8, and the pressure cover 16 are threadedly connected to protect the internal pipeline and form a combustion chamber at the same time. The elbow 15 is connected with the pressure pipe 11, and the mixed gas is injected into the combustion chamber through the elbow 15. The elbows 15 are fixed by rubber plugs.

[0021] In the gas-liquid separation device, the upper joint 1, the inlet ring 3, the cylinder 5 and the lower joint 6 are connected by a hole column to form an external shell, the upper joint 1 is connected to the connecting pipe 2 by a hole column and fixed inside the shell, and the spiral body 4 is connected to the connecting pipe 2 by a thread. The spiral body 4 and the connecting pipe 2 constitute a spiral device, which realizes the separation of natural gas and water vapor, realizes the drying process of natural gas, and ensures the combustion of natural gas.

[0022] The underground natural gas combustion heating device and the gas-liquid separation device are integrated through a hole column connection.

[0023] The integrated device for gas-liquid separation and combustion heating of natural gas hydrate designed by the present invention can realize the separation of natural gas and water vapor, dry the natural gas, and further promote the decomposition of natural gas hydrate by burning the natural gas produced by the decomposition of natural gas hydrate in the well and heating the formation. The specific working process is as follows:

[0024] The gas-liquid two-phase flow passes through the inlet ring 3 and axially enters the spiral body 4 of the spiral separation device. After passing through the guide blades, the two-phase flow changes from axial motion to spiral rotational motion. The centrifugal force on the droplets is large, the two phases are separated, and the droplets are captured by the outer wall of the flow channel. After the aggregation of the droplets and the action of gravity and airflow, the liquid flows down along the spiral body 4 in strands, and the gas is discharged upward from the spiral body 4 tube, completing the gas-liquid separation process.

[0025] The natural gas that has completed the gas-liquid separation continues to enter the underground natural gas combustion and heating device 19 from the gas-liquid separation device 20, wherein a part of the natural gas passes through the underground natural gas combustion and heating device 19 through the central pipe 10 and is sent to the ground through the underground pipe string; the other part of the natural gas is injected into the combustion chamber between the central pipe 10 and the pressure pipe 11 through the elbow 15, and is transported from the combustion chamber to the combustion port, and is ejected from the combustion port. The ground controls the operation of the underground igniter 17 through the cable to make the mixed gas burn, thereby heating the reservoir. The burned gas is discharged through the shell nozzle 8, and the unburned gas is discharged through the small nozzle 7.

[0026] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments, and any changes or modifications made based on the present invention belong to the scope of protection claimed by the present invention.

Claims

1. A natural gas hydrate underground gas-liquid separation and combustion heating integrated device, characterized in that: It includes underground natural gas combustion and heating device and gas-liquid separation device, which are mainly composed of shell nozzle, shell shell, small nozzle, small plug, central pipe, pressure pipe, gland, limit block, elbow, igniter, gasket, upper joint, inlet ring, connecting pipe, spiral body, cylinder, lower joint and rubber plug; In the underground natural gas combustion and heating device, the small nozzle is coaxially fixedly connected with the central tube, so that the natural gas is discharged from the small nozzle after being transported through the central tube. The limit block is connected with the pressure-bearing tube and the igniter through the hole axis, and the igniter is fixed on the pressure-bearing tube. The central tube is connected with the hole column between the small plug, and the central tube is fixed inside the pressure-bearing tube. The outer shell, the outer shell nozzle, and the pressure cover are connected by threads to protect the internal pipeline and form a combustion chamber at the same time. The elbow is connected with the pressure-bearing tube, and the mixed gas is injected into the combustion chamber through the elbow. The elbows are fixed by rubber plugs. In the gas-liquid separation device, the upper joint, the inlet ring, the cylinder and the lower joint are connected by a hole column to form an external shell, the upper joint is connected to the connecting pipe by the hole column and fixed inside the shell, and the spiral body and the connecting pipe are connected by a thread. The spiral body and the connecting pipe constitute a spiral device, which realizes the separation of natural gas and water vapor, realizes the drying process of natural gas, and ensures the combustion of natural gas.

2. The natural gas hydrate downhole gas-liquid separation and combustion heating integrated device according to claim 1, characterized in that: The underground natural gas combustion and heating device is integrated with the gas-liquid separation device through a hole column connection. The natural gas hydrate enters the gas-liquid separation device through the inlet ring, and the gas-liquid separation is achieved through the spiral device. The liquid flows down in strands along the spiral body, and the gas is discharged upward from the spiral body tube. Part of it is discharged from the small nozzle through the central pipe, and part of it is passed into the combustion chamber through the curved pipe for combustion.

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