An ejector-type casing gas recovery system and recovery method with adjustable nozzles

Abstract

This invention discloses an ejector-type casing gas recovery system with an adjustable nozzle, comprising a liquid inlet pipe and a gas inlet pipe. The liquid inlet pipe is divided into two paths: one path connects to the adjustable nozzle, which in turn connects to an ejector; the other path connects to a bypass branch pipe, which connects to a gas-liquid mixture outlet. The gas inlet pipe connects to the ejector, and the ejector end connects to the gas-liquid mixture outlet. This invention utilizes the low-pressure casing gas generated when extracted crude oil flows through the adjustable nozzle to achieve casing gas recovery. When the amount of casing gas recovered is too large or too small, or when crude oil production fluctuates, the flow area can be adjusted by adjusting the handwheel on the adjustable nozzle, thereby changing the ejector's drainage capacity and maintaining the recovered casing gas within a reasonable range. This invention has wide adaptability, is energy-saving and environmentally friendly, has a simple structure, is easy to install, is safe and reliable, and can be easily adjusted according to operating conditions, showing great promise for widespread application.

Description

Technical Field

[0001] This invention belongs to the field of oil well casing gas technology, specifically relating to an ejector-type casing gas recovery system with an adjustable nozzle, and also to an ejector-type casing gas recovery method with an adjustable nozzle. Background Technology

[0002] Large amounts of natural gas dissolve in the high-temperature, high-pressure formation oil to form dissolved gas. During crude oil production, as the pressure of the reservoir fluid flowing inside the wellbore decreases, the gas dissolved in the crude oil separates and enters the annular space between the casing and oil well, forming casing gas. If the casing opening is sealed, the natural gas inside the casing cannot be discharged, which will affect the pumping efficiency of the oil pump and may even cause gas lock in the pump, making it impossible to pump oil, thus significantly impacting crude oil production. To improve pumping efficiency, casing gas is sometimes directly vented into the air or burned, but this results in a waste of valuable energy and severe pollution of the atmosphere.

[0003] The existing casing gas recovery devices include the following types:

[0004] The mobile casing gas recovery device draws casing gas generated in the oil well into the primary separator through a valve, then through a high-pressure transition hose into the secondary separator. After the second separation, the relatively pure low-pressure gas enters the gas compressor unit for pressurization, and then enters the oil pipeline through a gas flow meter. However, if the casing gas volume is low, it cannot enter the oil pipeline, making large-scale promotion difficult.

[0005] The electrically heated casing gas recovery device connects the pressure regulating valve to the casing gas outlet, installs a pressure gauge on the pipeline to monitor the casing gas pressure in real time, connects the high-pressure hose to the high-pressure oil pipeline, and connects the gas collecting hose to the valve. The power supply is connected in parallel to the hose connector. By controlling the pressure regulating handwheel, the casing gas can be heated and recovered, thereby reducing the pressure in the annular space inside the casing. This method requires an external power supply.

[0006] The constant pressure venting valve casing gas recovery device is suitable for wellheads with high gas-liquid ratios. It achieves automatic venting of casing gas by setting a fixed pressure value, effectively reducing pump gas lock-up, improving well conditions, and increasing oilfield crude oil production. However, the spring is prone to corrosion, making it unsuitable for wells with severe sand production, and the venting valve is susceptible to freezing in winter.

[0007] The linkage-type casing gas recovery device utilizes the normal operation of the pumping unit to drive the piston, achieving up-and-down movement. This reciprocating motion drives the casing gas in and out of the pump cylinder, and finally, the casing gas enters the oil pipeline through the exhaust valve. This process equipment is costly and not suitable for use in areas with high wind and sand intensity.

[0008] The eccentric wellhead casing gas recovery device is installed on an eccentric wellhead. Gas accumulated in the casing annular space enters the recovery channel after passing through the valve seat orifice. When the pressure difference between the two sides exceeds the design value, the pressure control valve opens, and the recovered casing gas enters the oil export pipeline. This device is only suitable for eccentric wellheads, and its design concept is limited, preventing its widespread application in oil fields.

[0009] The skid-mounted light hydrocarbon casing gas recovery unit allows casing gas and natural gas volatilized from crude oil storage tanks to enter a gas-liquid separator together. The separated gas is then pressurized by a compressor, cooled, dried, and separated. It can be used as production fuel, processed into liquefied natural gas, or compressed and transported externally. However, this unit requires a large initial investment. Summary of the Invention

[0010] The purpose of this invention is to provide an ejector-type casing gas recovery system with an adjustable nozzle, which solves the problems of low recovery efficiency and high cost that exist in the prior art when casing gas recovery requires the installation of other equipment.

[0011] Another objective of this invention is to provide an ejector-type sleeve gas recovery method with an adjustable nozzle.

[0012] One technical solution adopted in this invention is an ejector-type sleeve gas recovery system with an adjustable nozzle, including a liquid inlet pipe and a gas inlet pipe. The liquid inlet pipe is divided into two paths: one path is connected to an adjustable nozzle, which is connected to an ejector, and the other path is connected to a bypass branch pipe, which is connected to a gas-liquid mixing outlet. The gas inlet pipe is connected to the ejector, and the end of the ejector is connected to the gas-liquid mixing outlet.

[0013] The invention is further characterized in that,

[0014] A solenoid valve a is installed on one side of the liquid inlet pipe, which connects to an adjustable nozzle. A solenoid valve b is installed on the other side, which connects to a bypass branch pipe.

[0015] A gas flow meter and a one-way safety valve are installed sequentially on the gas inlet pipe.

[0016] The adjustable nozzle includes a hollow cylindrical cavity with a fixed nozzle at one end. The fixed nozzle has a tapered opening that is wider at the top and narrower at the bottom. A tripod is installed inside the cavity, and a guide rod is slidably inserted into the tripod. The guide rod is coaxial with the fixed nozzle. A worm gear is sleeved on the guide rod, and the worm gear meshes with a turbine. The turbine is coaxially connected to an adjusting handwheel, which extends outside the cavity. An adjusting cone is connected to the end of the guide rod, and the conical surface of the adjusting cone is positioned opposite to the fixed nozzle.

[0017] Another technical solution adopted in this invention is an ejector-type casing gas recovery method with an adjustable nozzle, which is implemented according to the following steps:

[0018] Step 1: Open solenoid valve a and close solenoid valve b. The crude oil flowing out of the oil pipe will flow from the liquid inlet through the adjustable nozzle and be ejected at high speed, generating local low pressure.

[0019] Step 2: The casing gas in the casing is introduced into the ejector through the gas inlet, and the gas flow meter at the gas inlet measures the casing gas being drawn in.

[0020] Step 3: Calculate the recovery efficiency by measuring the gas volume in the casing using a gas flow meter. Adjust the flow area by adjusting the handwheel on the adjustable nozzle to change the ejector's flow capacity, so that the gas recovery volume in the casing is kept within a reasonable range and the casing pressure is kept within a reasonable range.

[0021] Step 4: The ejector exchanges momentum and energy to form a mixed fluid with moderate pressure, which flows out from the gas-liquid mixture outlet.

[0022] The invention is further characterized in that,

[0023] In step 3, when the amount of casing gas measured by the gas flow meter is too large, the adjusting handwheel of the adjustable nozzle is adjusted so that the adjusting cone moves towards the inlet of the fixed nozzle, thereby increasing the flow area of ​​the fixed nozzle. When the crude oil flow rate remains constant, the pressure at the outlet of the fixed nozzle increases, thereby weakening the suction capacity of the ejector and reducing the flow rate of the casing gas introduced.

[0024] When the amount of casing gas measured by the gas flow meter is too small, the adjusting handwheel of the adjustable nozzle is adjusted so that the adjusting cone moves towards the outlet of the fixed nozzle, thereby reducing the flow area of ​​the fixed nozzle. When the crude oil flow rate remains constant, the pressure at the outlet of the fixed nozzle decreases, thereby enhancing the suction capacity of the ejector and increasing the flow rate of the casing gas introduced.

[0025] In step 2, when the casing pressure is too low, open the one-way safety valve to prevent crude oil coming out of the tubing from entering the casing.

[0026] When ejector-type casing gas recovery is not required, close solenoid valve a and open solenoid valve b, and the crude oil coming out of the oil pipe will flow into the oil pipeline through the bypass branch pipe.

[0027] The beneficial effects of the present invention are as follows: The ejector-type casing gas recovery system with adjustable nozzle of the present invention has a simple structure, low cost, convenient operation, safety and environmental protection, no need to add external power device, wide adaptability, and the nozzle of the ejector is adjustable, which can adjust the size of the nozzle according to the working fluid flow rate or the casing gas recovery flow rate, thereby changing the ejector's flow capacity and ensuring high recovery efficiency. It has very important engineering application value for casing gas. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of an ejector-type sleeve gas recovery system with an adjustable nozzle according to the present invention;

[0029] Figure 2 This is a schematic diagram of the adjustable nozzle of an ejector-type sleeve gas recovery system with an adjustable nozzle according to the present invention.

[0030] Figure 3 This is a cross-sectional view of the adjustable nozzle of an ejector-type casing gas recovery system with an adjustable nozzle according to the present invention.

[0031] In the diagram, 1. Liquid inlet pipe, 2. Gas inlet pipe, 3. Gas flow meter, 4. One-way safety valve, 51. Solenoid valve a, 52. Solenoid valve b, 6. Bypass branch pipe, 7. Ejector, 8. Adjustable nozzle, 81. Fixed nozzle, 82. Adjusting cone, 83. Adjusting handwheel, 84. Turbine, 85. Worm gear, 86. Tripod, 87. Guide rod, 9. Gas-liquid mixture outlet. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0033] This invention discloses an ejector-type sleeve gas recovery system with an adjustable nozzle, such as... Figure 1 As shown, it includes a liquid inlet pipe 1 and a gas inlet pipe 2. The liquid inlet pipe 1 is divided into two paths. One path is connected to an adjustable nozzle 8, which is connected to an ejector 7. The other path is connected to a bypass branch pipe 6, which is connected to a gas-liquid mixing outlet 9. The gas inlet pipe 2 is connected to the ejector 7, and the end of the ejector 7 is connected to the gas-liquid mixing outlet 9.

[0034] One end of the liquid inlet pipe 1 is connected to solenoid valve a51, which connects to adjustable nozzle 8, and the other end is connected to solenoid valve b52, which connects to bypass branch pipe 6.

[0035] A gas flow meter 3 and a one-way safety valve 4 are installed sequentially on the gas inlet pipe 2.

[0036] like Figure 2 and Figure 3As shown, the adjustable nozzle 8 includes a hollow cylindrical cavity. A fixed nozzle 81 is installed at one end of the cavity. The fixed nozzle 81 has a tapered opening that is wider at the top and narrower at the bottom. A tripod bracket 86 is installed inside the cavity. A guide rod 87 is slidably inserted into the tripod bracket 86. The guide rod 87 is coaxial with the fixed nozzle 81. A worm gear 85 is sleeved on the guide rod 87. The worm gear 85 is engaged with a turbine 84. The turbine 84 is coaxially connected to an adjusting handwheel 83. The adjusting handwheel 83 extends outside the cavity. An adjusting cone 82 is connected to the end of the guide rod 87. The conical surface of the adjusting cone 82 is opposite to the fixed nozzle 81. The adjustable nozzle is constructed using a worm gear adjusting mechanism. By rotating the adjusting handwheel 83, the worm gear 85 drives the guide rod 87, which in turn moves the adjusting cone 82 up and down. The flow area between the adjusting cone 82 and the fixed nozzle 81 changes, thereby changing the flow capacity of the ejector 7.

[0037] This invention discloses an ejector-type casing gas recovery system with adjustable nozzles. It features a simple structure, small footprint, and convenient and quick installation. The liquid inlet pipe 1 and gas inlet pipe 2 are connected at both ends to the wellbore and oil pipeline, respectively. It is safe, reliable, and highly economical. Energy-saving and environmentally friendly, it requires no additional energy to recover casing gas. The processing technology is simple, and the manufacturing cost is low. It overcomes the shortcomings of existing recovery devices due to various reasons, operates stably and reliably, and is suitable for widespread application in oilfield enterprises.

[0038] This invention discloses a method for recovering gas from a casing with an adjustable nozzle. The method is implemented using the aforementioned system for recovering gas from a casing with an adjustable nozzle, specifically following these steps:

[0039] Step 1: Open solenoid valve a51 and close solenoid valve b52. The crude oil flowing out of the oil pipe will flow from the liquid inlet 1 through the adjustable nozzle 8 and be ejected at high speed, generating local low pressure.

[0040] Step 2: The casing gas in the casing is introduced into the ejector 7 through the gas inlet 2. The gas flow meter 3 at the gas inlet 2 measures the casing gas being introduced. In Step 2, when the casing pressure is too low, the one-way safety valve 4 is opened to prevent crude oil from the tubing from entering the casing.

[0041] Step 3: Calculate the recovery efficiency by measuring the gas flow rate in the casing using the gas flow meter 3. Adjust the flow area by adjusting the handwheel 83 on the adjustable nozzle 8 to change the flow capacity of the ejector 7, so that the gas recovery rate in the casing is kept within a reasonable range and the casing pressure is kept within a reasonable range.

[0042] When the amount of casing gas measured by the gas flow meter 3 is too large, the adjusting handwheel 83 of the adjustable nozzle 8 is adjusted so that the adjusting cone 82 moves toward the inlet of the fixed nozzle 81, thereby increasing the flow area of ​​the fixed nozzle 81. When the crude oil flow rate remains constant, the pressure at the outlet of the fixed nozzle 81 increases, thereby weakening the suction capacity of the ejector 7 and reducing the flow rate of the casing gas introduced.

[0043] When the amount of casing gas measured by the gas flow meter 3 is too small, the adjusting handwheel 83 of the adjustable nozzle 8 is adjusted so that the adjusting cone 82 moves toward the outlet of the fixed nozzle 81, thereby reducing the flow area of ​​the fixed nozzle 81. When the crude oil flow rate remains constant, the pressure at the outlet of the fixed nozzle 81 decreases, thereby enhancing the suction capacity of the ejector 7 and increasing the flow rate of the introduced casing gas.

[0044] Step 4: The ejector 7 exchanges momentum and energy to form a mixed fluid with moderate pressure, which flows out from the gas-liquid mixing outlet 9.

[0045] When ejector-type casing gas recovery is not required, close solenoid valve a51 and open solenoid valve b52, and the crude oil coming out of the oil pipe will flow into the oil pipeline through bypass branch pipe 6.

[0046] This invention discloses an ejector-type casing gas recovery method with an adjustable nozzle. The system utilizes ejector technology, taking advantage of the energy of the extracted crude oil to extract casing gas from the casing. The gas is then mixed with liquid and transported out, achieving the purpose of casing gas recovery. The nozzle in the ejector is adjustable, allowing the nozzle flow area to be adjusted according to different crude oil flow rates or casing gas recovery flow rates, generating the required suction pressure to ensure efficient casing gas recovery.

[0047] Example 1

[0048] This embodiment describes a gas recovery method system for an ejector sleeve with an adjustable nozzle. Through indoor testing, the flow rate and pressure difference of the liquid flowing through the ejector 7 were measured by changing the diameter of the adjustable nozzle 8. During the test, the one-way safety valve 4 was open, solenoid valve a51 was open, and solenoid valve b52 was closed. The diameter of the adjustable nozzle 8 was 5mm. The test results are as follows:

[0049] When the flow rate in inlet pipe 1 is 0.29 m³ / s 3 / h, the pressure difference before and after ejector 7 is 7.1kPa;

[0050] When the flow rate in inlet pipe 1 is 0.60 m³ / s 3 / h, the pressure difference before and after ejector 7 is 25.2kPa;

[0051] When the flow rate in inlet pipe 1 is 0.80 m³ / s 3 / h, the pressure difference before and after ejector 7 is 41.2kPa;

[0052] When the flow rate in inlet pipe 1 is 1m 3 / h, the pressure difference before and after ejector 7 is 65kPa;

[0053] When the flow rate in inlet pipe 1 is 1.2 m³ / s 3 / h, the pressure difference before and after ejector 7 is 107kPa.

[0054] The statistical results of the experiment are shown in Table 1:

[0055] Table 1 shows the measurement data for a 5mm ejector nozzle.

[0056] Pressure difference / kPa 7.1 25.2 41.2 62.3 107

[0057] As shown in Table 1, as the flow rate through the liquid inlet pipe 1 increases, the pressure difference before and after the ejector 7 also increases significantly. The stronger the gas ejection capability of the device, the greater the pressure difference is, and the gas recovery rate of the device is positively correlated with the gas recovery rate of the device.

[0058] Example 2

[0059] This embodiment describes a gas recovery method system for an ejector sleeve with an adjustable nozzle. Through indoor experiments, different diameters of the adjustable nozzle 8 were changed to test the liquid flow rate and pressure difference flowing through the ejector 7. During the experiment, the one-way safety valve 4 was open, solenoid valve a51 was open, and solenoid valve b52 was closed. When the diameter of the adjustable nozzle 8 was 3mm, the test results are as follows:

[0060] When the flow rate in inlet pipe 1 is 0.21 m³ / s 3 / h, the pressure difference before and after ejector 7 is 65.1kPa;

[0061] When the flow rate in inlet pipe 1 is 0.40 m³ / s 3 / h, the pressure difference before and after ejector 7 is 196.0 kPa;

[0062] When the flow rate in inlet pipe 1 is 0.60 m³ / s 3 / h, the pressure difference before and after ejector 7 is 331.1kPa;

[0063] When the flow rate in inlet pipe 1 is 0.80 m³ / s 3 / h, the pressure difference before and after ejector 7 is 780kPa;

[0064] When the flow rate in inlet pipe 1 is 1.0 m³ / s 3 / h, the pressure difference before and after ejector 7 is 1010kPa.

[0065] The statistical results of the experiment are shown in Table 2:

[0066] Table 2 shows the measurement data for a 3mm ejector nozzle.

[0067] Pressure difference kPa 65.1 196.0 331.1 780.0 1010.0

[0068] As shown in Table 2, as the flow rate through the liquid inlet pipe 1 increases, the pressure difference before and after the ejector 7 also increases significantly. The stronger the gas ejection capability of the device, the greater the pressure difference is, and the gas recovery rate of the device is positively correlated with the gas recovery rate of the device.

[0069] Compared with Example 2, under the same flow rate, the nozzle diameter was reduced from 5mm to 3mm, and the pressure difference before and after the ejector 7 was also significantly increased, resulting in a stronger sleeve gas ejection capability of the device. Example 3

[0070] This embodiment presents an ejector-type casing gas recovery method with an adjustable nozzle. The method is implemented using the aforementioned ejector-type casing gas recovery system with an adjustable nozzle, specifically following these steps:

[0071] Step 1: Open solenoid valve a51 and close solenoid valve b52. The crude oil flowing out of the oil pipe will flow from the liquid inlet 1 through the adjustable nozzle 8 and be ejected at high speed, generating local low pressure.

[0072] Step 2: The casing gas in the casing is introduced into the ejector 7 through the gas inlet 2, and the gas flow meter 3 at the gas inlet 2 measures the casing gas being introduced.

[0073] Step 3: The gas flow rate of the casing is measured by the gas flow meter 3. If the gas flow rate of the casing is too high, the adjusting handwheel 83 of the adjustable nozzle 8 is adjusted so that the adjusting cone 82 moves towards the inlet of the fixed nozzle 81, thereby increasing the flow area of ​​the fixed nozzle 81. When the crude oil flow rate remains constant, the pressure at the outlet of the fixed nozzle 81 increases, thereby weakening the suction capacity of the ejector 7 and reducing the flow rate of the introduced casing gas. This keeps the amount of casing gas recovered within a reasonable range and maintains the casing pressure within a reasonable range.

[0074] Step 4: The ejector 7 exchanges momentum and energy to form a mixed fluid with moderate pressure, which flows out from the gas-liquid mixing outlet 9.

[0075] Example 4

[0076] This embodiment presents an ejector-type casing gas recovery method with an adjustable nozzle. The method is implemented using the aforementioned ejector-type casing gas recovery system with an adjustable nozzle, specifically following these steps:

[0077] Step 1: Open solenoid valve a51 and close solenoid valve b52. The crude oil flowing out of the oil pipe will flow from the liquid inlet 1 through the adjustable nozzle 8 and be ejected at high speed, generating local low pressure.

[0078] Step 2: The casing gas in the casing is introduced into the ejector 7 through the gas inlet 2. The gas flow meter 3 at the gas inlet 2 measures the casing gas being introduced. In Step 2, when the casing pressure is too low, the one-way safety valve 4 is opened to prevent crude oil from the tubing from entering the casing.

[0079] Step 3: The gas flow rate of the casing is measured by the gas flow meter 3. When the gas flow rate of the casing measured by the gas flow meter 3 is too small, the adjusting handwheel 83 of the adjustable nozzle 8 is adjusted so that the adjusting cone 82 moves towards the outlet of the fixed nozzle 81, thereby reducing the flow area of ​​the fixed nozzle 81. When the crude oil flow rate remains unchanged, the pressure at the outlet of the fixed nozzle 81 decreases, thereby enhancing the suction capacity of the ejector 7 and increasing the flow rate of the introduced casing gas.

[0080] Step 4: The ejector 7 exchanges momentum and energy to form a mixed fluid with moderate pressure, which flows out from the gas-liquid mixing outlet 9.

[0081] When ejector-type casing gas recovery is not required, close solenoid valve a51 and open solenoid valve b52, and the crude oil coming out of the oil pipe will flow into the oil pipeline through bypass branch pipe 6.

Claims

1. An ejector-type casing gas recovery system with an adjustable nozzle, characterized in that, It includes a liquid inlet pipe (1) and a gas inlet pipe (2). The liquid inlet pipe (1) is divided into two paths. One path is connected to an adjustable nozzle (8), which is connected to an ejector (7). The other path is connected to a bypass branch pipe (6), which is connected to a gas-liquid mixture outlet (9). The gas inlet pipe (2) is connected to the ejector (7), and the end of the ejector (7) is connected to the gas-liquid mixture outlet (9). A solenoid valve a (51) is installed on one side of the liquid inlet pipe (1), which is connected to an adjustable nozzle (8). A solenoid valve b (52) is installed on the other side, which is connected to a bypass branch pipe (6). A gas flow meter (3) and a one-way safety valve (4) are sequentially installed on the gas inlet pipe (2); The adjustable nozzle (8) includes a hollow cylindrical cavity, with a fixed nozzle (81) at one end of the cavity. The fixed nozzle (81) has a tapered opening that is larger at the top and smaller at the bottom. A tripod (86) is provided inside the cavity. The tripod (86) is slidably connected to a guide rod (87). The guide rod (87) is coaxial with the fixed nozzle (81). A worm gear (85) is sleeved on the guide rod (87). The worm gear (85) is meshed with a turbine (84). The turbine (84) is coaxially connected to an adjusting handwheel (83). The adjusting handwheel (83) extends out of the cavity. An adjusting cone (82) is connected to the end of the guide rod (87). The conical surface of the adjusting cone (82) is opposite to the fixed nozzle (81).

2. A method for recovering gas from a casing with an adjustable nozzle, utilizing the ejector-type casing gas recovery system with an adjustable nozzle as described in claim 1, characterized in that, The specific steps are as follows: Step 1: Open solenoid valve a (51) and close solenoid valve b (52). The crude oil flowing out of the oil pipe will flow from the liquid inlet (1) through the adjustable nozzle (8) and be ejected at high speed to generate local low pressure. Step 2: The casing gas in the casing is introduced into the ejector (7) through the gas inlet (2), and the gas flow meter (3) at the gas inlet (2) measures the casing gas being drawn in. Step 3: Calculate the recovery efficiency by measuring the gas volume in the casing using the gas flow meter (3), and adjust the flow area by adjusting the adjustment handwheel (83) on the adjustable nozzle (8) to change the flow capacity of the ejector (7) so that the gas recovery volume in the casing is kept within a reasonable range and the casing pressure is kept within a reasonable range. Step 4: The ejector (7) exchanges momentum and energy to form a mixed fluid with moderate pressure, which flows out from the gas-liquid mixing outlet (9).

3. The ejector-type casing gas recovery method with an adjustable nozzle according to claim 2, characterized in that, In step 3, when the amount of casing gas measured by the gas flow meter (3) is too large, the adjusting handwheel (83) of the adjustable nozzle (8) is adjusted so that the adjusting cone (82) moves toward the inlet of the fixed nozzle (81), thereby increasing the flow area of ​​the fixed nozzle (81). When the crude oil flow rate remains unchanged, the pressure at the outlet of the fixed nozzle (81) increases, thereby weakening the suction capacity of the ejector (7) and reducing the flow rate of the casing gas introduced. When the amount of casing gas measured by the gas flow meter (3) is too small, the adjusting handwheel (83) of the adjustable nozzle (8) is adjusted so that the adjusting cone (82) moves toward the outlet of the fixed nozzle (81), thereby reducing the flow area of ​​the fixed nozzle (81). When the crude oil flow rate remains unchanged, the pressure at the outlet of the fixed nozzle (81) decreases, thereby enhancing the suction capacity of the ejector (7) and increasing the flow rate of the casing gas introduced.

4. The ejector-type casing gas recovery method with an adjustable nozzle according to claim 2, characterized in that, In step 2, when the casing pressure is too low, open the one-way safety valve (4) to prevent crude oil coming out of the tubing from entering the casing.

5. The ejector-type casing gas recovery method with an adjustable nozzle according to claim 2, characterized in that, When ejector-type casing gas recovery is not required, close solenoid valve a (51) and open solenoid valve b (52), and the crude oil coming out of the oil pipe will flow into the oil pipeline through the bypass branch pipe (6).

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