CN105545279B - A kind of defeated device of the pipe of gas hydrates - Google Patents

Abstract

The invention discloses a pipeline transportation device for natural gas hydrate, which comprises a well bottom casing, a hydrocyclone, an ESP tank-shaped container system, and a pipeline exchange device; the hydrocyclone, the ESP tank-shaped container system, and a pipeline The line exchange device is connected sequentially from bottom to top and fixed in the casing at the bottom of the well; the hydrocyclone includes a cyclone inlet, a cyclone overflow port, a cyclone cylinder, and a cyclone cone. body, bottom flow port; the ESP tank-shaped container system is divided into upper and lower parts by a partition plate, including a container inlet, a drain pump motor, a gas-liquid separator, and a drain pump; the line exchange system includes a fluid input pipeline, Packers, pipeline exchange devices, gas transmission pipelines, fluid transmission pipelines. The invention realizes the solid-liquid-gas three-phase separation of the natural gas hydrate through the hydrocyclone, the ESP tank-shaped container system, and the pipeline line exchange device, collects and transports the natural gas to the sea surface, discharges the solid phase and the liquid phase at the same time, and improves the mining efficiency.

Description

A pipeline transportation device for natural gas hydrate

technical field

The invention relates to the field of marine natural gas hydrate equipment, in particular to a pipeline transportation device for natural gas hydrate.

Background technique

Natural gas hydrate, also known as combustible ice, is an ice-like crystalline substance formed by natural gas and water under high pressure and low temperature conditions. It is an unconventional energy source with high density and high calorific value. 1m ³ natural gas hydrate can release 64m ³ methane gas and 0.8m ³ water), and the natural gas hydrate has high methane content and low combustion pollution.

Natural gas is mainly distributed in the ocean and terrestrial permafrost deposits with a water depth greater than 300m. Marine gas hydrates are usually buried at 0-1100m below the seabed, and the ore layer is tens of centimeters to hundreds of meters thick. 10,000 square meters, and its resources are more than 100 times that of land tundra. It is estimated that the total amount of global gas hydrate resources converted into methane gas is about 1.8-2.1×10 ¹⁶ cubic meters, which is equivalent to twice the total known energy reserves of coal, oil and natural gas in the world. Therefore, natural gas hydrate, especially marine natural gas hydrate, is generally considered to be a new type of clean energy resource to replace coal, oil and natural gas in the 21st century, and it is also a new energy source with the largest untapped reserves.

As a new energy source, the large-scale exploitation and transportation of natural gas hydrate is also in the exploration stage. One of the main difficulties is that the seabed natural gas hydrate cannot be effectively transported to the ground. The mining of natural gas hydrate is generally accompanied by sediment, and the water content of the hydrate is relatively large, which is likely to cause freezing of pipelines, etc., and three-phase separation is required before pipeline transportation; at the same time, natural gas hydrate is a greenhouse gas, and its greenhouse effect in the atmosphere is 25 times that of carbon dioxide, once it leaks, it will inevitably lead to aggravation of global warming. Therefore, it is necessary to achieve sealing during pipeline transportation to prevent leakage. Due to the above-mentioned technical difficulties and the changeable and complex seabed environment, there is no large-scale commercial exploitation of natural gas hydrates.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a natural gas hydrate separation and transportation device during the natural gas hydrate exploitation process. The device separates the natural gas hydrate mixed with mud into solid-liquid-gas three-phase separation, and transports natural gas and water to the sea surface through different pipelines. The invention can efficiently collect seabed natural gas resources and meet the demand for large-scale transportation of seabed natural gas hydrate resources.

A pipeline transportation device for natural gas hydrate, comprising a bottom hole casing, a hydrocyclone, an ESP (electric submersible pump) tank-shaped container system, and a line exchange system; the hydrocyclone, the ESP tank-shaped container system, and a circuit The exchange system is connected sequentially from bottom to top and fixed in the casing at the bottom of the well; the hydrocyclone includes a cyclone inlet, a cyclone overflow port, a cyclone cylinder, and a cyclone cone , Bottom flow port; the ESP tank-shaped container system is divided into upper and lower parts by a partition plate, the lower part of the ESP tank-shaped container system includes the container inlet and the drain pump motor, and the upper part of the ESP tank-shaped container system includes a gas-liquid separator , liquid discharge pump, the gas-liquid separator inlet is provided below the gas-liquid separator, and the gas-liquid separator vent hole is provided above, and the ESP tank-shaped container system wall has an air outlet hole on the wall surface below the partition plate, and the ESP tank There is an exhaust port on the upper wall of the container system and communicates with the vent hole of the gas-liquid separator. There is a return port on the top of the ESP tank-shaped container system, and an annular space is formed between the wall of the ESP tank-shaped container system and the motor of the drainage pump; The line exchange system includes a fluid input pipeline, a packer, a pipeline line exchange device, a gas delivery pipeline, and a fluid delivery pipeline, wherein the bottom hole casing and the fluid input pipeline form an annulus 2; the ESP tank-shaped container system The inlet of the lower container is connected to the cyclone overflow port at the upper end of the hydrocyclone through a conduit, and the upper end of the ESP tank-like container system is connected to the fluid input pipeline of the line exchange system through a gas-liquid separator.

Further, the ESP tank-shaped container system has 3 rows of air outlets on the upper wall below the partition board, located at 2 to 5 cm below the partition board, and the interval between the 3 air outlets is 5 cm, and each air outlet is 4. The diameter of the air outlet is 2cm, and it is distributed in a circle along the axis of the ESP tank-shaped container system; the exhaust ports on the upper wall of the ESP tank-shaped container system are two axisymmetric holes, which are respectively connected to the left and right two holes set above the gas-liquid separator. The vent hole of the gas-liquid separator is connected; the top of the ESP tank-shaped container system has a return port, which is distributed in a circle along the axis of the ESP tank-shaped container system. The edge of the return port is 0.5cm away from the edge of the wall, and the number is 8. It is 2cm.

Further, the exhaust port is provided with a one-way valve opening outwards to ensure the release of the internal liquid and to isolate the external air.

Further, the upper and lower ends of the packer on the pipeline line exchange device are equipped with rubber sleeves, which expand under the compression of the packer, and are in close contact with the casing at the bottom of the well for compaction; to prevent natural gas or water from overflowing, At the same time, the isolation pressure makes the pressure below the packer greater than the pressure above, so that the natural gas and water are transported upward.

Further, the gas delivery pipeline and the fluid delivery pipeline are connected to the central axis of the pipeline exchange device, the fluid delivery pipeline has a length of 20 cm installed in the gas delivery pipeline, and the diameter of the fluid delivery pipeline installed in the gas delivery pipeline is Half of the gas delivery pipeline in this section, then the gas delivery pipeline and the fluid delivery pipeline are separated, the gas delivery pipeline is reduced to 60% of the previous diameter after separation, and the fluid delivery pipeline diameter remains unchanged.

Further, a power cable is buried in the wall of the bottom hole casing.

Further, a heating cable is buried in the well wall of the bottom hole casing section where the ESP tank-like container system is located to heat the natural gas hydrate.

The pipeline transportation device for natural gas hydrate is installed in the casing under the submarine blowout preventer, so that the natural gas hydrate mixture passes through the hydrocyclone, the ESP tank-like container system, and the pipeline line exchange device in sequence, and the gas hydrate mixture is placed under the seabed ground. The gas-liquid separation is completed in the casing, the separated gas is transported to the sea surface, and the liquid is discharged into the sea.

The advantages of the present invention are:

1. The present invention can separate the solid and liquid from the natural gas hydrate mixture mixed with sediment to obtain relatively pure natural gas hydrate;

2. The present invention can separate natural gas hydrate into gas and liquid, and transport the separated gas and liquid phases through different pipelines, so as to collect natural gas more conveniently and efficiently;

3. The present invention has simple structure, few power mechanisms, is not easy to be damaged under severe seabed conditions, reduces maintenance and replacement frequency, ensures operation continuity, and saves production costs.

Description of drawings

Fig. 1 is a schematic structural view of a hydrocyclone of the present invention;

Fig. 2 is the structural representation of ESP tank container system of the present invention;

Fig. 3 is a schematic diagram of the structure of the pipe line switching device of the present invention.

In the figure, 1 is the liquid inlet of the cyclone, 2 is the overflow port of the cyclone, 3 is the cylinder of the cyclone, 4 is the cone of the cyclone, 5 is the bottom flow port, and 6 is the bottom casing. 8 is annulus 1, 9 is a discharge pump motor, 10 is an air outlet, 11 is a partition plate, 12 is an inlet of a gas-liquid separator, 13 is a gas-liquid separator, 14 is an exhaust port, and 15 is a gas-liquid separator Exhaust hole, 16 is the drainage pump, 17 is the return port, 18 is the fluid input pipeline, 19 is the second annular space, 20 is the pipeline line exchange device, 21 is the packer, 22 is the gas delivery pipeline, 23 is the fluid delivery pipeline.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments in the accompanying drawings, but this does not constitute any limitation to the present invention.

As shown in Figures 1 to 3, a natural gas hydrate pipeline transportation device includes a bottom hole casing 6, a hydrocyclone, an ESP tank-like container system, and a line exchange system; the hydrocyclone, ESP tank The container system and the line exchange system are connected sequentially from bottom to top (upper left and lower right in the figure), and are fixed in the bottom casing 6; the hydrocyclone includes a hydrocyclone inlet 1, a hydrocyclone overflow Port 2, cyclone cylinder 3, cyclone cone 4, bottom flow port 5; the ESP tank-shaped container system is divided into upper and lower parts by a partition plate 11, and the lower half of the ESP tank-shaped container system includes the container inlet 7. The liquid discharge pump motor 9, the upper part of the ESP tank-shaped container system includes a gas-liquid separator 13 and a liquid discharge pump 16. The gas-liquid separator inlet 12 is provided below the gas-liquid separator 13, and the gas-liquid separator is provided above. The vent hole 15 of the separator, the wall of the ESP tank-shaped container system is provided with a vent hole 10 on the wall below the partition plate 11, and the upper wall of the ESP tank-shaped container system is provided with a vent port 14 and communicated with the vent hole 15 of the gas-liquid separator , the top of the ESP tank-shaped container system has a return port 17, and an annular space-8 is formed between the wall surface of the ESP tank-shaped container system and the drain pump motor 9; the line exchange system includes a fluid input pipeline 18, a packer 21, Pipeline exchange device 20, gas delivery pipeline 22, fluid delivery pipeline 23, wherein the bottom hole casing 6 and the fluid input pipeline 18 form an annulus 2 19; the lower end container inlet 7 of the ESP tank-shaped container system passes through the conduit and the hydrocyclone The cyclone overflow port 2 at the upper end of the flow device is connected, and the upper end of the ESP tank container system is connected with the fluid input pipeline 18 of the pipeline line exchange device through the gas-liquid separator 13 .

The hydrocyclone is the mud removal equipment of the present invention, which can perform preliminary separation of the natural gas hydrate mixture mixed with sediment to obtain a relatively pure natural gas hydrate solid-liquid mixture; the ESP tank-shaped container system is the gas-liquid separation of the present invention The device can separate the natural gas hydrate mixture naturally and artificially, and transport the separated natural gas and water through different pipelines; the pipeline line exchange device can exchange the separated gas and water pipelines, so that it is more Convenient and efficient collection of natural gas.

As shown in Figure 1, the hydrocyclone mainly includes a cyclone inlet 1, a cyclone overflow port 2, a cyclone cylinder 3, a cyclone cone 4, and a bottom flow port 5. The hydrocyclone is a centrifugal cyclone, which relies on the density difference between solid and liquid to separate solid and liquid. The mixed liquid is transported tangentially into the liquid inlet 1 of the cyclone at a certain pressure, and the mixed liquid rushes in at high speed along the wall of the cyclone cylinder 3 to form a high-speed rotating flow field. Under the action of the field, it moves downward in the axial direction, and at the same time moves outward in the radial direction. When it reaches the cone 4 of the cyclone, it moves downward along the wall and is discharged from the bottom flow port 5, thus forming an external vortex flow field; The components with low density move toward the central axis, and form an upward inner vortex on the central axis, and flow upward to the overflow port 2 of the cyclone through the inner vortex, thus achieving the purpose of separation.

As shown in Figure 2, the ESP tank-shaped container system includes a container inlet 7, a liquid drainage pump motor 9, a gas-liquid separator 13, and a liquid drainage pump 16, which can realize the two-phase separation of natural gas hydrate and separate natural gas and water into Different pipelines are transported to the sea surface to avoid secondary crystallization of gas hydrates. Due to its special structure, natural gas hydrate mixed fluids that have been desanded for the first time can be naturally separated. As can be seen from the figure, the middle part of the tank body is divided into upper and lower parts by a partition plate 11, and the fluid can flow into the inside of the container through the cyclone overflow port 2 connected to the bottom of the container. There are 3 outlet holes 10 on the top of the inner wall of the lower part of the container, and the number of each outlet 10 is 4. The upper and lower outlet holes 10 are aligned, and the middle outlet 10 and the upper and lower outlet holes 10 are alternately arranged for the fluid flowing into the container. out of the container; wherein the system's drain pump motor 9 is located in the lower half of the container, and the area of the drain pump motor 9 is sealed to prevent water. The gas-liquid separator 13 is located above the bottom packer in the upper half of the container, and the drain pump 16 is located in the upper half of the gas-liquid separator. The top of the upper half of the container is provided with a return port 17 for fluid to flow in. The working principle of the ESP tank-shaped container system is: the natural gas hydrate mixed fluid flows into the lower half of the container from the bottom of the system, flows out of the container through the air outlet 10, flows into the annular area between the ESP tank-shaped container system and the water riser, and continues upward flow. When the fluid flows upward through the upper part of the tank, the fluid here is weakened by the action of the pump, and the natural gas in the natural gas hydrate mixed fluid continues to flow upward due to its low density, while the liquid dissolved in natural gas flows from the return port 17 under the action of gravity. It flows into the upper half of the space inside the system, and finally passes through the gas-liquid separator 13 to separate the natural gas dissolved in water. The natural gas is discharged through the gas-liquid separator exhaust hole 15 above the gas-liquid separator 13, and flows upward together with the mixed fluid. The water continues to flow upwards through the action of the pump. In this way, the separation of gas hydrate is realized. A heating cable is installed in the 6 sections of the bottom hole casing corresponding to the ESP tank-shaped container system to generate a certain amount of heat during the transportation of natural gas hydrate to prevent its secondary crystallization. Cables to provide power to the drainage pump 16, heating cables, hydrocyclone inlet pumps and other power equipment.

FIG. 3 is a schematic diagram of the pipeline exchange device system. The device mainly includes a fluid input pipeline 18 , a packer 21 , a pipeline exchange device 20 , a gas delivery pipeline 22 , and a fluid delivery pipeline 23 . The device can collect the gas flowing in the second annulus 19 and transport it to the sea surface through the gas delivery pipeline 22, while the water flow is transported upward through the fluid delivery pipeline 23, flows into the throttling manifold and finally discharges into the sea. Coaxial pipelines are used to design the initial outlets of the gas delivery pipeline 22 and the fluid delivery pipeline 23, the purpose of which is to facilitate the installation of cables for power adapters on the pipeline line switching device 20, so as to avoid taking up more space due to the initial outlets being discharged separately by two lines Space, and the use of multiple cables needs to be sealed, packaged and fixed separately. The underground space is small and the environment is harsh, which is not conducive to the construction in place. In order to ensure the stable operation of the system, it is necessary to avoid too scattered wiring arrangement.

Example:

An example flow of the method of the present invention is: the natural gas hydrate on the seabed is in a stable state under the seabed environment, and when the external environment changes, the natural gas hydrate will decompose from solid to liquid and gaseous. The natural gas hydrate collected on the seabed is usually a gas-liquid mixture, and a certain amount of sediment is generally mixed in the mixture. The natural gas hydrate pipeline transportation device of the present invention separates the natural gas hydrate mixture from solid-liquid to gas underwater, and then transports the separated natural gas and water to the sea surface.

Firstly, the steady state of natural gas is changed by decompression method, the natural gas hydrate mixture containing sediment is collected and transported to the hydrocyclone, and the sediment in the mixture is removed by centrifugal force separation, and the natural gas hydrate mixed liquid to be treated is extracted from the hydrocyclone The liquid inlet 1 of the device enters the hydrocyclone at a high speed, resulting in a high angular velocity. At the same angular velocity, solids and liquids produce different centrifugal inertial forces due to density differences. The denser sediment is thrown to the inside of the wall of the cone 4 of the hydrocyclone, while the lower-density natural gas hydrate mixture liquid and gas are Near the center of the hydrocyclone. While the silt is thrown to the inside of the wall of the cone body 4 of the cyclone, it also moves downward in a spiral manner along the inside of the wall of the cone body 4 of the cyclone, and finally is discharged to the seabed by the bottom outlet 5. The high-speed rotation of the liquid at the center of the hydrocyclone forms a low-pressure spiral upward flow, and most of the liquid and gas are transported upward through the cyclone overflow port 2 along with the upward flow.

The gas hydrate mixture flows upward through the pipeline and the action of the ESP. The natural gas hydrate mixture fluid enters the lower part of the container from the inlet 7 below the ESP tank-shaped container system through the pipeline, and the fluid continues to flow upward in the annular space 18 in the container, during which the fluid passes through the drainage pump motor 9 of the ESP system Strictly sealed to prevent water from entering, it flows below the middle packer 11 of the container, flows out of the container through the small hole 10 opened in the container wall, and continues to flow upward in the annular space area between the outer wall of the container and the casing. The motor area 9 generates a certain amount of heat during operation, which can effectively prevent the secondary crystallization of natural gas hydrate. The upper and lower parts of the container are separated by a packer 11 . When the gas-liquid mixture flows to the top of the ESP tank-shaped container system, the gas in the mixed fluid continues to flow upwards, and the liquid flows into the upper part of the ESP tank-shaped container system through the return port 17 above the tank container due to the action of gravity. The upper half of the container flows downwards, reaches the bottom of the upper half of the container, and enters the gas-liquid separator 13 at the bottom. The gas dissolved in the liquid is separated by the action of the gas-liquid separator, and the gas is discharged out of the container through the exhaust port 14 on the pipe wall. The exhaust port 14 is equipped with a one-way valve to prevent the inflow of external liquid, and the discharged gas Combined with fluid flow from the lower half of the vessel, the gas flows upward as the combined flow passes over the top of the vessel, while the liquid flows into the upper half of the vessel as previously described. The main component of the liquid separated by the gas-liquid separator 13 is water, which is transported upwards through the fluid pipeline 18 of the container, while the natural gas flows upwards between the fluid pipeline 18 and the annular region between the bottom hole casing 6 . In addition, the heating cable on the riser wall will also generate a certain amount of heat, avoiding the risk of its secondary crystallization.

After the gas-liquid separation, the water flows upward in the fluid pipeline 18, while the natural gas is processed and enters the annulus 2 19 formed outside the fluid pipeline 18 and the corresponding bottom hole casing 6 pipe sections, and the fluid pipeline 18 is exchanged with a pipeline circuit 20 connected. In this device, the separated gas is collected from the annulus 2 19 through a binary flow head through the exchange of pipelines and flows into the gas delivery pipeline 22 , and is finally delivered to the sea surface deck through the gas delivery pipeline 22 for collection. The water flows through the device into the fluid delivery pipeline 23 and flows upwards and finally is discharged into the sea through the throttling manifold. Wherein the packer 21 on the device can prevent the fluid from overflowing during transportation, and at the same time provide a pressure difference to facilitate the upward flow of the fluid.

The above description is only a preferred embodiment of the present invention. It should be pointed out that the present invention is not limited to the above-mentioned manner. On the premise of not departing from the principle of the present invention, further improvements can be made, and these improvements should also be regarded as the scope of protection of the present invention. .

Claims (7)

1. A pipeline transport device for natural gas hydrate, characterized in that it comprises a bottom hole casing (6), a hydrocyclone, an ESP tank-shaped container system, and a line exchange system, and the ESP tank-shaped container system is an electric submersible Pump tank-shaped container system; the hydrocyclone, ESP tank-shaped container system, and line exchange system are connected sequentially from bottom to top, and are fixed in the bottom hole casing (6); the hydrocyclone includes a hydrocyclone Liquid inlet (1), cyclone overflow port (2), cyclone cylinder (3), cyclone cone (4), bottom flow port (5); the ESP tank-shaped container system is The partition plate (11) is divided into upper and lower parts, the lower part of the ESP tank-shaped container system includes the container inlet (7) and the liquid discharge pump motor (9), and the upper half of the ESP tank-shaped container system includes the gas-liquid separator (13) , liquid discharge pump (16), described gas-liquid separator (13) below is provided with gas-liquid separator inlet (12), is provided with gas-liquid separator exhaust hole (15) above, and ESP tank-shaped container system wall is in There is an air outlet (10) on the upper part of the lower wall of the partition plate (11), and an exhaust port (14) is opened on the upper wall of the ESP tank-shaped container system and communicated with the gas-liquid separator vent (15). The ESP tank-shaped container system There is a return port (17) at the top, and an annulus one (8) is formed between the wall surface of the ESP tank-shaped container system and the drainage pump motor (9); the line exchange system includes a fluid input pipeline (18), a packer (21), pipeline line exchange device (20), gas delivery pipeline (22), fluid delivery pipeline (23), wherein bottom hole casing (6) and fluid input pipeline (18) form annular space two (19); The container inlet (7) at the lower end of the ESP tank-shaped container system is connected to the cyclone overflow port (2) at the upper end of the hydrocyclone through a conduit, and the upper end of the ESP tank-shaped container system is connected to the circuit through a gas-liquid separator (13) The fluid input pipe (18) of the exchange system is connected. 2. The pipeline transportation device of a kind of natural gas hydrate as claimed in claim 1, it is characterized in that, the number of air outlet holes (10) that the ESP tank-shaped container system has on the top of the wall below the partition plate (11) is 3 Row, located at 2 to 5 cm below the partition plate, 3 exhaust air holes (10) are separated by 5 cm, each exhaust air hole is 4, the diameter of the air outlet is 2 cm, and is distributed along the axis of the ESP tank-shaped container system in a circle; ESP tank-shaped The exhaust port (14) on the upper wall of the container system is two axisymmetric holes, which communicate with the left and right gas-liquid separator exhaust holes (15) arranged above the gas-liquid separator (13); the ESP tank-shaped There is a return port (17) on the top of the container system, which is distributed along the axis of the ESP tank-shaped container system. The distance between the edge of the return port and the edge of the wall is 0.5 cm. The number of return ports is 8, and the diameter of the return port is 2 cm. 3. A pipeline transportation device for natural gas hydrate as claimed in claim 2, characterized in that, the exhaust port (14) is provided with a one-way valve opening outward to ensure the release of internal gas and isolate external liquid . 4. A pipeline transportation device for natural gas hydrate as claimed in claim 1, characterized in that, the upper and lower ends of the packer (21) on the pipeline exchange device (20) are provided with rubber cartridges, and the rubber cartridges It expands under the compression of the packer (21), and is in close contact with the bottom hole casing (6) for compaction; to prevent natural gas or water from overflowing, and at the same time, the isolated pressure makes the pressure below the packer (21) greater than the pressure above, so that the natural gas and water is transported upwards. 5. A pipeline transportation device for natural gas hydrate as claimed in claim 1, characterized in that, the gas delivery pipeline (22) and the fluid delivery pipeline (23) are connected to the central axis of the pipeline exchange device (20), and the fluid The delivery pipeline (23) has a section of length that is installed in the gas delivery pipeline (22) for a pipeline of 20cm, and the pipe diameter of the fluid delivery pipeline (23) installed in the gas delivery pipeline (22) is this section of the gas delivery pipeline (22) Then the gas delivery pipeline (22) and the fluid delivery pipeline (23) are separated, and the gas delivery pipeline (22) is reduced to 60% of the previous pipe diameter after separation, and the fluid delivery pipeline (23) pipe diameter remains unchanged. 6. A pipeline transportation device for natural gas hydrate according to claim 1, characterized in that a power cable is buried in the wall of the bottom hole casing (6). 7. The pipeline transportation device of a kind of natural gas hydrate as claimed in claim 1, it is characterized in that, a heating cable is buried in the well wall of the bottom hole casing (6) section where the ESP tank-shaped container system is located, and the natural gas Hydrate is heated.