A gas field wellhead throttling and pressure reduction device and method based on vortex tube effect

Abstract

The present invention belongs to the field of gas field wellhead throttling and pressure reduction technology, and is designed to utilize the radial static temperature pressure gradient inside the vortex tube and the unique flow field structure of the gradually increasing axial static temperature of the hot end tube. A gas field wellhead throttling and pressure reduction device based on the vortex tube effect includes an integrated cabinet, an air intake pipeline connected to the inlet end of the integrated cabinet, a liquid collection pipeline and a gas collection pipeline connected to the outlet end of the integrated cabinet; and also includes a vortex tube; a primary throttling and pressure reduction device is arranged inside the integrated cabinet, and the primary throttling and pressure reduction device includes a plurality of vortex tubes arranged in parallel; the air intake pipeline is connected to the inlet end of the vortex tube through a reducer; the wellhead throttling and pressure reduction process developed by the present invention using the vortex tube as the core component can effectively avoid a series of technical difficulties such as the easy failure and difficulty of salvaging of the downhole throttle, high energy consumption of wellhead heating, and greater risk of unattended operation, which can significantly improve social and economic benefits, play a role in saving energy consumption, and promote the development of gas field surface gathering and transportation technology.

Description

Technical Field

[0001] The invention belongs to the field of gas field wellhead throttling and pressure reduction technology, and is designed to utilize the radial static temperature pressure gradient inside the vortex tube and the unique flow field structure of gradually increasing axial static temperature of the hot end tube. Background Art

[0002] The downhole throttling technology of natural gas fields is a new technology promoted in recent years for economical and efficient development. Yanchang Petroleum Yanqi 2-Yan 128 Well Area and Yan 145 Well Area have adopted this technology. It can not only effectively utilize the formation energy rewarming and realize the wellbore throttling and pressure reduction, but also significantly simplify the gas gathering station process and reduce the ground construction investment. However, for sour gas fields, due to the corrosiveness of hydrogen sulfide, the reliability and stability of the downhole throttling device is difficult to guarantee, and it is difficult to repair, maintain and salvage, which causes certain safety risks.

[0003] Therefore, in sulfur-containing gas fields, downhole throttling is generally not used, and surface throttling technology is usually used. However, the traditional surface throttling gathering and transportation technology requires heating throttling, so the process is generally more complicated and the investment is higher.

[0004] To sum up, if we can explore and invent a new type of high-efficiency and energy-saving gas field wellhead throttling device with a simple structure and no need for heating, which can achieve throttling and pressure reduction at the gas wellhead without hydrate freezing, it will be of great significance and value for the advancement of gas field surface gathering and transportation technology.

[0005] The vortex tube is a simple energy separation device, which consists of a nozzle, a vortex chamber, a separation orifice plate and hot and cold end tubes. Figure 1 As shown in the figure, during operation, the compressed gas expands in the nozzle and then enters the vortex tube at a very high speed along the tangential direction. When the airflow rotates at high speed in the vortex tube, it is separated into two parts of airflow with unequal temperatures after vortex transformation, and obvious pressure gradients are generated in both radial and axial directions. According to the needs of the application example, the ratio of cold and hot flows can be adjusted to obtain the best cooling effect or heating effect. Summary of the invention

[0006] In view of the above problems, the present invention proposes a device which utilizes the radial static temperature and pressure gradient inside the vortex tube and the unique flow field structure of gradually increasing axial static temperature of the hot end tube to achieve throttling and pressure reduction at the wellhead of the gas field without performing wellhead heating and without producing hydrates.

[0007] The technical solution of the present invention is:

[0008] A gas field wellhead throttling and pressure reduction device based on vortex tube effect, comprising an integrated cabinet, an air intake pipeline connected to the inlet end of the integrated cabinet, a liquid collection pipeline and a gas collection pipeline connected to the outlet end of the integrated cabinet;

[0009] It also includes a vortex tube, which includes a vortex chamber and a cold end tube and a hot end tube respectively located at both ends of the vortex chamber and connected to the vortex chamber; the outlet ends of the cold end tube and the hot end tube are connected to expansion tubes, which are respectively a cold end expansion tube and a hot end expansion tube; the inlet end of the vortex chamber is connected to a reducer; a shell and tube heat exchanger connected to the cold end tube is arranged around the connection between the cold end tube and the vortex tube; the hot end expansion tube is also connected to the shell and tube heat exchanger through a heating pipeline;

[0010] A primary throttling and pressure reducing device is provided inside the integrated cabinet, and the primary throttling and pressure reducing device includes a plurality of vortex tubes arranged in parallel; the air intake pipelines are connected to the inlet ends of the vortex tubes through reducers, and the diameter of the reducers in the air intake direction along the air intake pipelines tends to decrease;

[0011] It also includes a primary merging system located outside the integrated cabinet, the primary merging system includes a first heat exchanger, a first pressure stabilizer and a first gas-liquid separator connected in sequence; the hot end expansion tubes are all connected to the first pressure stabilizer, and the cold end expansion tubes are all connected to the first heat exchanger; the gas outlet end of the first gas-liquid separator is connected to the gas collecting pipeline, and the liquid outlet end is connected to the liquid collecting pipeline.

[0012] It also includes a secondary throttling and pressure reducing device located in the integrated cabinet and a secondary merging system located outside the integrated cabinet; the secondary throttling and pressure reducing device includes vortex tubes of the same number and structure as those in the primary throttling and pressure reducing device; the secondary merging system includes a second heat exchanger, a second pressure stabilizer and a second gas-liquid separator connected in sequence; wherein the gas outlet end of the first gas-liquid separator is connected to the inlet end of the vortex tube in the secondary throttling and pressure reducing device through a reducer; similarly, in the secondary throttling and pressure reducing device, the hot end expansion tubes are all connected to the second pressure stabilizer, and the cold end expansion tubes are all connected to the second heat exchanger; the gas outlet end of the second gas-liquid separator is connected to the gas collecting pipeline, and the liquid outlet end of the first gas-liquid separator and the liquid outlet end of the second gas-liquid separator are both connected to the liquid collecting pipeline.

[0013] It also includes a third gas-liquid separator, wherein the gas outlet end of the third gas-liquid separator is connected to the gas inlet pipeline, and the liquid outlet end of the third gas-liquid separator is connected to the liquid collecting pipeline.

[0014] There are four vortex tubes in the primary throttling and pressure reducing device and the secondary throttling and pressure reducing device.

[0015] The air intake pipeline is also provided with a safety valve.

[0016] The connecting pipelines from the hot end expansion pipe to the shell and tube heat exchanger, the first pressurizer and the second pressurizer are all provided with a thermal insulation layer.

[0017] A gas field wellhead throttling and pressure reduction method based on vortex tube effect, using the gas field wellhead throttling and pressure reduction device based on vortex tube effect as described above, the steps are as follows:

[0018] 1) The natural gas from the wellhead enters the third gas-liquid separator, and the gas phase enters the primary throttling and pressure reduction device in the integrated cabinet through the air inlet pipeline for primary throttling and pressure reduction: cold and hot separation is carried out in the vortex tube to precipitate free water, and the free water is led out to the first stabilizer through the hot end expansion pipe and the hot end main pipe with the high-temperature gas, and the other part of the high-temperature gas is transported to the shell and tube heat exchanger through the heating pipeline to heat the cold end pipe, and mixed with the low-temperature gas in the cold end pipe. After mixing, it is connected to the first heat exchanger through the cold end main pipe, and the cold and hot flows are mixed in the first stabilizer for reheating. The reheated airflow enters the first gas-liquid separator, and the free water enters the liquid collecting pipeline; the airflow after the free water is removed enters the integrated cabinet again and undergoes secondary throttling and pressure reduction through the secondary throttling and pressure reduction device;

[0019] 2) During the secondary throttling and pressure reduction, free water enters the liquid collecting pipeline, and the air flow after the free water is removed enters the gas collecting pipeline.

[0020] The cold flow ratio of the hot and cold separation is 1:2.

[0021] The technical effects of the present invention are:

[0022] The wellhead throttling and pressure reduction process developed by the present invention using the vortex tube as the core component can effectively avoid a series of technical difficulties such as the easy failure and difficulty in salvaging of the downhole throttle, high energy consumption for wellhead heating, and greater risk of unattended operation. It can significantly improve social and economic benefits, play a role in saving energy consumption, and promote the development of gas field surface gathering and transportation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural principle diagram of a vortex tube in the background technology.

[0024] Figure 2 The present invention is a schematic structural diagram of a gas field wellhead throttling and pressure reduction device based on the vortex tube effect.

[0025] Figure 3 Schematic diagram of the structure of the vortex tube of the present invention.

[0026] Figure markings: 1-reducing pipe, 2-shell and tube heat exchanger, 3-vortex chamber, 4-hot end expansion pipe, 5-cold end expansion pipe, 6-first heat exchanger, 7-first pressure stabilizer, 8-first gas-liquid separator, 9-second heat exchanger, 10-second pressure stabilizer, 11-second gas-liquid separator, 13-liquid collecting tank, 14-cold end main pipe, 15-hot end main pipe, 16-safety valve. DETAILED DESCRIPTION

[0027] Example 1

[0028] A gas field wellhead throttling and pressure reduction device based on vortex tube effect, comprising an integrated cabinet, an air intake pipeline connected to the inlet end of the integrated cabinet, a liquid collection pipeline and a gas collection pipeline connected to the outlet end of the integrated cabinet;

[0029] It also includes a vortex tube, which includes a vortex chamber 3 and a cold end tube and a hot end tube respectively located at both ends of the vortex chamber 3 and connected to the vortex chamber 3; the outlet ends of the cold end tube and the hot end tube are connected to expansion tubes, which are a cold end expansion tube 5 and a hot end expansion tube 4 respectively; the inlet end of the vortex chamber 3 is connected to a reducer 1 to increase the inlet gas velocity and improve the cold and hot separation performance of the vortex tube; a shell and tube heat exchanger 2 connected to the cold end tube is arranged around the connection between the cold end tube and the vortex tube; the hot end expansion tube 4 is also connected to the shell and tube heat exchanger 2 through a heating pipeline;

[0030] A primary throttling and pressure reducing device is provided inside the integrated cabinet, and the primary throttling and pressure reducing device includes a plurality of vortex tubes arranged in parallel; the air intake pipelines are connected to the inlet ends of the vortex tubes through reducers 1, respectively, and the diameter of the reducers 1 along the air intake direction of the air intake pipelines tends to decrease;

[0031] It also includes a primary merging system located outside the integrated cabinet, and the primary merging system includes a first heat exchanger 6, a first pressure stabilizer 7 and a first gas-liquid separator 8 connected in sequence; the hot end expansion tubes 4 are all connected to the first pressure stabilizer 7, and the cold end expansion tubes 5 are all connected to the first heat exchanger 6; the gas outlet end of the first gas-liquid separator 8 is connected to the gas collecting pipeline, and the liquid outlet end is connected to the liquid collecting pipeline, and the liquid collecting pipeline is connected to the liquid collecting tank 13.

[0032] The specific implementation process of this embodiment is as follows:

[0033] The wellhead natural gas enters each vortex tube through the air inlet pipeline. The high-pressure gas entering the vortex tube is separated into cold and hot in the vortex chamber 3. In the vortex chamber 3, due to the drop in static temperature, free water is precipitated and thrown to the high-temperature wall under the action of the strong cyclone in the vortex chamber 3. It flows out from the hot end pipe to the hot end expansion pipe 4 along with the high-temperature gas; after the flow rate is reduced and the static temperature and static pressure are increased in the hot end expansion pipe 4, a part of it is led out to the first stabilizer 7 through the hot end main pipe 15; the other part of the high-temperature gas is transported to the shell and tube heat exchanger 2 through the heating pipeline, and the heat exchanger 2 is heated by the hot end main pipe 15. It enters through the upper shell side of the shell and tube heat exchanger 2 and flows out from the lower shell side to heat the cold end tube. The high-temperature gas flowing out from the lower shell side is led to the cold end tube to mix with the low-temperature gas. The mixed gas flows through the cold end expansion tube 5 to increase the static pressure and static temperature, and then flows into the cold end main pipe 14 and is led to the first heat exchanger 6. After heat exchange with the air to increase the static temperature, it also enters the first stabilizer 7; it is mixed with the high-temperature gas in the first stabilizer 7 for reheating; the reheated gas enters the first gas-liquid separator 8, the free water enters the liquid collecting pipeline, and the gas enters the gas collecting pipeline.

[0034] Example 2

[0035] On the basis of Example 1, it also includes:

[0036] It also includes a secondary throttling and pressure reducing device located in the integrated cabinet and a secondary merging system located outside the integrated cabinet; the secondary throttling and pressure reducing device includes vortex tubes of the same number and structure as those in the primary throttling and pressure reducing device; the secondary merging system includes a second heat exchanger 9, a second pressure stabilizer 10 and a second gas-liquid separator 11 connected in sequence; wherein, the gas outlet end of the first gas-liquid separator 8 is connected to the inlet end of the vortex tube in the secondary throttling and pressure reducing device through a reducer 1; similarly, in the secondary throttling and pressure reducing device, the hot end expansion tube 4 is connected to the second pressure stabilizer 10, and the cold end expansion tube 5 is connected to the second heat exchanger 9; the gas outlet end of the second gas-liquid separator 11 is connected to the gas collecting pipeline, and the liquid outlet end of the first gas-liquid separator 8 and the liquid outlet end of the second gas-liquid separator 11 are connected to the liquid collecting pipeline.

[0037] The specific implementation process of this embodiment is as follows:

[0038] The gas outlet end of the first gas-liquid separator 8 is no longer connected to the gas collecting pipeline, but is directly passed into the vortex tube in the secondary throttling and pressure reduction device in the integrated cabinet for secondary throttling and pressure reduction; the throttling and pressure reduction process is the same as that in Example 1; the airflow after secondary throttling and pressure reduction enters the second gas-liquid separator 11, the free water enters the liquid collecting pipeline, and the gas enters the gas collecting pipeline.

[0039] Example 3

[0040] On the basis of Example 2, the invention further includes:

[0041] It also includes a third gas-liquid separator, the gas outlet end of which is connected to the gas inlet pipeline, and the liquid outlet end of which is connected to the liquid collecting pipeline. Wellhead natural gas first enters the third gas-liquid separator, removes part of free water, condensate oil and solid impurities, effectively avoids the subsequent heterogeneous nucleation of natural gas hydrates in the vortex tube, and then enters the integrated cabinet through the gas inlet pipeline.

[0042] Example 4

[0043] On the basis of Example 3, it also includes: the number of the vortex tubes is 4. The air intake pipeline is also provided with a safety valve 16. When the equipment in the integrated cabinet fails and causes the pipeline pressure to exceed the set value, the safety valve 16 will automatically pop open to ensure the safety and reliability of the process. The connecting pipelines from the hot end expansion tube 4 to the shell and tube heat exchanger 2, the first stabilizer 7 and the second stabilizer 10 are all provided with insulation layers.

[0044] The devices involved in the present invention are all commercially available products except the vortex tube. For example, the models of the first gas-liquid separator 8, the second gas-liquid separator 11 and the third gas-liquid separator are all Φ400mm×L1726 PN 8MPA. The models of the first regulator 7 and the second regulator 10 are Φ200mm×H800 PN 8MPA. The models of the first heat exchanger 6 and the second heat exchanger 9 are LRGG-4-3.6×2.8 / 9-5.7.

Claims

1. A gas field wellhead throttling and pressure reduction device based on vortex tube effect, comprising an integrated cabinet, an air intake pipeline connected to the inlet end of the integrated cabinet, a liquid collection pipeline and a gas collection pipeline connected to the outlet end of the integrated cabinet; characterized in that: It also includes a vortex tube, the vortex tube including a vortex chamber (3) and a cold end tube and a hot end tube respectively located at two ends of the vortex chamber (3) and connected to the vortex chamber (3); the outlet ends of the cold end tube and the hot end tube are connected to expansion tubes, namely the cold end expansion tube (5) and the hot end expansion tube (4); the inlet end of the vortex chamber (3) is connected to a reducer (1); a shell and tube heat exchanger (2) connected to the cold end tube is arranged around the connection between the cold end tube and the vortex tube; the hot end expansion tube (4) is also connected to the shell and tube heat exchanger (2) through a heating pipeline; A primary throttling and pressure reducing device is provided inside the integrated cabinet, and the primary throttling and pressure reducing device comprises a plurality of vortex tubes arranged in parallel; the air intake pipelines are connected to the inlet ends of the vortex tubes through reducers (1), and the diameter of the reducers (1) tends to decrease along the air intake direction of the air intake pipelines; It also includes a primary merging system located outside the integrated cabinet, the primary merging system including a first heat exchanger (6), a first pressure stabilizer (7) and a first gas-liquid separator (8) connected in sequence; the hot end expansion tubes (4) are all connected to the first pressure stabilizer (7), and the cold end expansion tubes (5) are all connected to the first heat exchanger (6); the gas outlet end of the first gas-liquid separator (8) is connected to the gas collecting pipeline, and the liquid outlet end is connected to the liquid collecting pipeline; It also includes a secondary throttling and pressure reducing device located in the integrated cabinet and a secondary merging system located outside the integrated cabinet; the secondary throttling and pressure reducing device includes vortex tubes of the same number and structure as those in the primary throttling and pressure reducing device; the secondary merging system includes a second heat exchanger (9), a second pressure regulator (10) and a second gas-liquid separator (11) connected in sequence; wherein the gas outlet end of the first gas-liquid separator (8) is connected to the inlet end of the vortex tube in the secondary throttling and pressure reducing device through a reducer (1); similarly, in the secondary throttling and pressure reducing device, the hot end expansion tube (4) is connected to the second pressure regulator (10), and the cold end expansion tube (5) is connected to the second heat exchanger (9); the gas outlet end of the second gas-liquid separator (11) is connected to the gas collecting pipeline, and the liquid outlet end of the first gas-liquid separator (8) and the liquid outlet end of the second gas-liquid separator (11) are connected to the liquid collecting pipeline; It also comprises a third gas-liquid separator (12), wherein the gas outlet end of the third gas-liquid separator (12) is connected to the gas inlet pipeline, and the liquid outlet end of the third gas-liquid separator (12) is connected to the liquid collecting pipeline; There are four vortex tubes in the primary throttling and pressure reducing device and the secondary throttling and pressure reducing device; The air intake pipeline is also provided with a safety valve (16); The connecting pipelines from the hot end expansion tube (4) to the shell and tube heat exchanger (2), the first pressurizer (7) and the second pressurizer (10) are all provided with a thermal insulation layer; The specific usage is: The natural gas from the wellhead enters the third gas-liquid separator (12), and the gas phase enters the primary throttling and pressure reduction device in the integrated cabinet through the gas inlet pipeline for primary throttling and pressure reduction: the cold and hot are separated in the vortex tube to precipitate free water, and the free water is led out to the first stabilizer (7) through the hot end expansion pipe (4) and the hot end main pipe (15) along with the high-temperature gas, and the other part of the high-temperature gas is transported to the shell and tube heat exchanger (2) through the heating pipeline to heat the cold end pipe, and is mixed with the low-temperature gas in the cold end pipe. After mixing, it is connected to the first heat exchanger (6) through the cold end main pipe (14), and the cold and hot flows are mixed in the first stabilizer (7) for reheating. The reheated gas flow enters the first gas-liquid separator (8), and the free water enters the liquid collecting pipeline; the gas flow after the free water is removed enters the integrated cabinet again and is subjected to secondary throttling and pressure reduction through the secondary throttling and pressure reduction device; During the secondary throttling and pressure reduction, free water enters the liquid collecting pipeline, and the airflow after the free water is removed enters the gas collecting pipeline.

2. The gas field wellhead throttling and pressure reduction device based on the vortex tube effect according to claim 1 is characterized in that: The cold flow ratio of the hot and cold separation is 1:2.

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