A system for recovery of vented natural gas from a drained oil and gas well

Abstract

The present application belongs to the technical field of oilfield exploitation, and provides a system for recovering vented natural gas of a drainage oil and gas well, comprising: a compressor, which comprises a screw compressor and a reciprocating compressor, the screw compressor and the reciprocating compressor are connected in series, and the screw compressor is located at the front end of the air inlet; a separator, which is connected between the compressor and the wellhead connecting pipe, and the separator is connected with a waste oil tank.In the present application, a widely applicable skid-mounted system is provided, which changes the mode of general single equipment and control, adopts a combination of multiple types of equipment, plus load adjustment and backflow control, and adapts to the wide range of changes of natural gas at different periods of the drainage wellhead, so that the rapid and continuous recovery of scattered natural gas becomes possible, the emission of natural gas is maximally reduced, and the natural environment is effectively protected.The system is designed in a skid type and manufactured in a factory, and has the advantages of compact structure, easy transportation and relocation, etc.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oilfield exploitation, and particularly relates to a system for recovering vented natural gas of a drainage oil and gas well. BACKGROUND

[0002] During the processes of exploitation, oil testing, liquid drainage, etc., a certain amount of natural gas is generated in an oil and gas well, and the amount and stability of the gas vary greatly. Generally, the gas is directly vented and discharged or burned by a flare, which causes resource waste and environmental pollution.

[0003] In order to solve the problems of energy waste and environmental pollution caused by venting natural gas during the drainage of an oil and gas well mouth, a natural gas recovery system for the oil and gas well mouth is currently used to recover the vented natural gas. The existing natural gas recovery system for the oil and gas well mouth is an integrated skid-mounted device composed of a separation metering skid, a compressor skid, and a dehydration and dealkylation skid, and is widely used for natural gas recovery during the processes of exploitation, oil testing, and liquid drainage of an oil and gas well. In order to adapt to various gas ranges, the Tarim Oilfield of PetroChina has arranged three levels of 2x10 4 m 3 / d, 3x10 4 m 3 / d, and 5x10 4 m 3 / d to achieve the purpose of adjusting the production capacity (Natural Gas and Petroleum, No. 5, 2012, P23, Li Xunji, etc.). The Natural Gas Branch of Daqing Oilfield has a large amount of vented natural gas during the processes of gas testing and production testing of a natural gas exploration and evaluation well, and the vented gas amount of each well varies greatly, ranging from 3 to 20x10 4 m 3 / d. The operation flexibility of the recovery equipment is limited. The Natural Gas Branch has designed a gas taking valve group skid that meets the above conditions. When the pressure of the venting pipeline is higher than 0.5 MPa, the regulating valve is opened to release part of the gas to the recovery flare, and when the pressure of the venting pipeline is lower than 0.5 MPa, the regulating valve is closed to recover as much vented gas as possible (Energy Saving of Petroleum and Petrochemical Industry, No. 11, 2016, P48.49, Zhang Dandi and Li Yue). The existing natural gas recovery system for the oil and gas well mouth is designed to have multiple skids of different levels to adapt to various gas ranges. Different skid-mounted devices of different levels are selected for different well mouths, and different skid-mounted devices of different levels are replaced for the same well mouth at different periods, which reduces the work efficiency and interrupts the continuous production of the well mouth. In addition, each level of skid-mounted device cannot recover all the natural gas beyond the range. If the skid-mounted device is replaced or increased, the transportation and hoisting costs are increased. SUMMARY

[0004] The present application aims to provide a system for recovering vented natural gas of a drainage oil and gas well, and aims to solve the technical problem of poor adaptability of the skid-mounted device for recovering natural gas in the prior art.

[0005] The object of the present application can be achieved by the following technical solutions:

[0006] A system for recovering vented natural gas of a production oil and gas well, comprising a wellhead connecting pipe, a dirty oil tank, a dehydration pry, a natural gas pipeline and a tank truck pipeline, further comprising:

[0007] A compressor, comprising a screw compressor and a reciprocating compressor, the screw compressor and the reciprocating compressor being connected in series, and the screw compressor being located at the front end of the air inlet;

[0008] A separator, connected between the compressor and the wellhead connecting pipe, and connected with the dirty oil tank.

[0009] As a preferred embodiment of the above technical solution, the separator comprises two low-pressure separators and a high-pressure separator, the air inlet end of the screw compressor is connected with the low-pressure separator, the low-pressure separator is connected with the wellhead connecting pipe, the low-pressure separator is connected with the dirty oil tank, a slide valve is installed at the air inlet end of the screw compressor, a frequency controller is installed on the output of the screw compressor, an air cooler is connected with the air outlet end of the screw compressor, the air outlet end of the air cooler is connected with the high-pressure separator, the air outlet end of the air cooler is also connected with a return pipeline, the end of the return pipeline is connected with the air inlet end of the screw compressor, the high-pressure separator is connected with the dirty oil tank, the air outlet end of the high-pressure separator is connected with the reciprocating compressor, another frequency controller is installed on the output of the reciprocating compressor, another air cooler is connected with the air outlet end of the reciprocating compressor, the air outlet end of the air cooler is connected with a buffer tank, the air outlet end of the air cooler is also connected with another return pipeline, the end of the return pipeline is connected with the air inlet end of the reciprocating compressor, and the air outlet end of the buffer tank is connected with the dehydration pry.

[0010] As a preferred embodiment of the above technical solution, the separator further comprises a high-pressure separator, natural gas enters the separator through the wellhead connecting pipe, wherein natural gas with a pressure less than or equal to 3 MPa enters the low-pressure separator, and natural gas with a pressure greater than or equal to 3 MPa enters the high-pressure separator, wherein natural gas with a pressure equal to 3 MPa enters the low-pressure separator, is pressurized by the screw compressor, and then directly enters the natural gas pipeline without entering the reciprocating compressor, and natural gas with a pressure equal to 25 MPa directly enters the dehydration pry without passing through the screw compressor or the reciprocating compressor.

[0011] As a preferred embodiment of the above technical solution, an air inlet pipe is connected to the periphery of the separator, a sealing door is installed on the surface of the separator, an exhaust pipe is connected through the top of the separator, an oil discharge cylinder, a filter screen and an aeration pipe are installed in the inner cavity of the separator from top to bottom, the oil discharge cylinder penetrates through the bottom of the separator, the filter screen is located outside the oil discharge cylinder, and an auxiliary mechanism is installed on the filter screen.

[0012] As the preferred technical solution of the above, the auxiliary mechanism comprises:

[0013] The rotating rod is installed in the exhaust pipe and the impeller is fixed on the periphery of the rotating rod;

[0014] The bottom of the rotating rod is fixed with a fixed plate, the bottom of the fixed plate is provided with a plurality of connecting plates, the bottom of the plurality of connecting plates is provided with a circular ring, the circular ring is located on the outside of the oil discharge cylinder, and the outer surface of the circular ring is attached to the inner side of the filter screen;

[0015] The outer side of the circular ring is provided with a plurality of upper cleaning brushes and a plurality of lower cleaning brushes, the plurality of upper cleaning brushes are located above the filter screen, and the plurality of lower cleaning brushes are located below the filter screen.

[0016] As the preferred technical solution of the above, the opposite sides of the two adjacent upper cleaning brushes are provided with baffles.

[0017] As the preferred technical solution of the above, the oil discharge cylinder comprises an inner cylinder and an outer cylinder, a plurality of partition plates are arranged between the inner cylinder and the outer cylinder, a discharge chamber is formed between two adjacent partition plates, a plurality of through holes are formed in the periphery of the oil discharge cylinder, the positions of the plurality of through holes coincide with those of the plurality of partition plates, and a sealing cover is arranged on the top of the outer cylinder.

[0018] As the preferred technical solution of the above, a plurality of oil inlet pipes are arranged through the periphery of the oil discharge cylinder, the oil inlet pipes are arranged to be inclined downward from the outside of the oil discharge cylinder to the inside of the oil discharge cylinder, the inner side of the connecting plate is an inclined surface and is inclined toward the rotating direction of the rotating rod.

[0019] As the preferred technical solution of the above, a liquid level sensor is arranged on the inner wall of the separator, the liquid level sensor is on the same horizontal plane as the top of the oil discharge cylinder, a drain pipe is arranged on the separator, the drain pipe is located between the aeration pipe and the filter screen, an electromagnetic valve is arranged on the drain pipe, and the liquid level sensor and the electromagnetic valve are connected with an external control unit.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] 1. In the present application, a widely applicable pry system is provided, which changes the mode of general single equipment and control, adopts a plurality of types of equipment combination, adds load adjustment and reflux control, adapts to large-scale changes of natural gas in different periods of the wellhead, makes it possible to quickly and continuously recover scattered natural gas, maximally reduces the emission of natural gas, and effectively protects the natural environment. The system is designed to be pry-shaped, manufactured in a factory, has the advantages of compact structure, easy transportation and relocation, etc.

[0022] 2. In the present application, a separator suitable for 2×104 m 3 / d, 3x10 4 m 3 / d, 5x10 4 m 3 / d three levels of system, change the multi-sled collocation, adapt to the same wellhead different period, need not multiple pry collocation.Select screw compressor and reciprocating compressor two model combination, cooperate load regulation, frequency conversion control and backflow control, adapt to the wide change of natural gas pressure, realize the total recovery of the natural gas during the test production;

[0023] 3. In the application, two whole prying are designed, which can be stacked on site, convenient for transportation, save space, and can also be used separately, saving investment;

[0024] 4. In the application, bubbles are generated by aeration through the aeration pipe, the bubbles slowly rise, and the bubbles contact the oil stains on the surface of the impurities in the rising process, since the oil stains have certain surface activity and viscosity, the bubbles can be adsorbed on the surface of the oil stains, so that the oil stains are slowly taken away from the bottom of the water, and the oil stains are slowly separated from the impurities; at the same time, the existence of the bubbles increases the average density of the water, so that the buoyancy of the impurities with relatively large density increases, so that the impurities slowly float up, in the process of floating up, the bubbles are adsorbed on the surface of the oil stains, so that the oil stains are slowly separated from the impurities, and the separated impurities slowly sink; in addition, the bubbles cause the flow and disturbance of the water, the disturbance effect of the water flow helps to break the adhesion between the oil stains and the impurities, so that the oil stains are more easily taken away by the bubbles and float up, thereby improving the separation efficiency of the oil stains and the impurities; the separation mode of the oil stains and the impurities does not easily affect the purity of the natural gas. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a whole process flow chart of the application;

[0026] Figure 2 It is a compressor process flow chart;

[0027] Figure 3 It is a separator structure schematic diagram;

[0028] Figure 4 It is a separator internal structure schematic diagram;

[0029] Figure 5 It is an exhaust pipe internal structure schematic diagram;

[0030] Figure 6 It is a partial structure split schematic diagram;

[0031] Figure 7 It is an auxiliary mechanism structure schematic diagram;

[0032] Figure 8Schematic diagram of the oil drain cylinder structure.

[0033] In the picture:

[0034] 1. Wellhead connecting pipe; 2. Separator; 2a. Low-pressure separator; 2b. High-pressure separator 1; 2c. High-pressure separator 2; 21. Inlet pipe; 22. Sealing door; 3. Sewage oil tank; 4. Compressor; 41. Screw compressor; 411. Slide valve; 42. Reciprocating compressor; 5. Dehydration skid; 6. Natural gas pipeline; 7. Tank truck pipeline; 8. Air cooler; 9. Buffer tank; 10. Frequency converter; 11. Return pipe; 12. Exhaust Air pipe; 13. Aeration pipe; 14. Filter screen; 15. Oil drain cylinder; 151. Discharge chamber; 152. Partition; 153. Through hole; 154. Oil inlet pipe; 155. Sealing cover; 16. Auxiliary mechanism; 161. Rotating rod; 162. Impeller; 163. Fixing plate; 164. Connecting plate; 165. Ring; 166. Upper cleaning brush; 167. Lower cleaning brush; 168. Baffle; 17. Drain pipe; 18. Liquid level sensor. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0037] like Figure 1 and Figure 2 As shown, a system for recovering natural gas from venting oil and gas wells includes a wellhead connecting pipe 1, a slop oil tank 3, a dehydration skid 5, a natural gas pipeline 6, and a tank truck pipeline 7. The system also includes:

[0038] Compressor 4, which includes a screw compressor 41 and a reciprocating compressor 42. The screw compressor 41 and the reciprocating compressor 42 are connected in series, and the screw compressor 41 is located at the front end of the air intake;

[0039] The separator 2 is connected between the compressor 4 and the wellhead connecting pipe 1, and the separator 2 is connected to the waste oil tank 3.

[0040] In one case of this embodiment, the boosting range of the screw compressor 41 is 0.5 MPa-3 MPa, and the boosting range of the reciprocating compressor 42 is 3 MPa-25 MPa.

[0041] In actual application, the natural gas from the wellhead enters the skid-mounted system, first passes through the separator 2 for pre-separation, separates part of the free oil and sewage in the natural gas, and the natural gas after the preliminary treatment enters the compressor 4 for pressurization. In order to adapt to the pressure range of 0.5-25 MPa, the screw compressor 41 and the reciprocating compressor 42 are connected in series. The series connection breaks through the low limit of 1.0 MPa of the inlet pressure of the reciprocating compressor 42, and the advantages of the two devices are complementary, meeting the requirements of the 25 MPa tank car, expanding the adaptability of the skid-mounted device to the wellhead pressure, saving energy consumption, and making the system more adaptable.

[0042] The reciprocating compressor 42 is suitable for high compression ratio application field, and the maximum compression ratio reaches 20:1. The reciprocating compressor 42 is designed to change the number of compressor cylinders to adapt to different wellhead parameters.

[0043] Further, the separator 2 includes a low-pressure separator 2a and a high-pressure separator 2c. The inlet end of the screw compressor 41 is connected with the low-pressure separator 2a, the low-pressure separator 2a is connected with the wellhead connecting pipe 1, the low-pressure separator 2a is connected with the oil tank 3, the inlet end of the screw compressor 41 is provided with a slide valve 411, the output end of the screw compressor 41 is provided with a frequency converter 10, the outlet end of the air cooler 8 is connected with the high-pressure separator 2c, the outlet end of the air cooler 8 is further connected with a backflow pipe 11, the outlet end of the backflow pipe 11 is connected with the inlet end of the screw compressor 41, the high-pressure separator 2c is connected with the oil tank 3, the outlet end of the high-pressure separator 2c is connected with the reciprocating compressor 42, the output end of the reciprocating compressor 42 is provided with another frequency converter 10, the outlet end of the air cooler 8 is connected with the buffer tank 9, the outlet end of the air cooler 8 is further connected with another backflow pipe 11, the outlet end of the backflow pipe 11 is connected with the inlet end of the reciprocating compressor 42, and the outlet end of the buffer tank 9 is connected with the dehydration pry 5.

[0044] In actual application, the screw compressor 41 is controlled by automatically adjusting the opening of the slide valve 411 according to the inlet pressure to adapt to load changes, the rotating speed of the screw compressor 41 is adjusted by the frequency converter 10 to adjust the processing capacity of the compressor in time, the slide valve 411 and the frequency converter 10 are used to meet the requirements of low gas flow range, and the operation can be ensured even in the case of low gas flow (natural gas interruption), and the wellhead gas flow changes in a wide range are adapted to; in the control of the reciprocating compressor 42, the inlet pressure is stabilized by the backflow pipeline 11 in the case of low flow to expand the operation range and save energy, the rotating speed of the reciprocating compressor 42 is adjusted by the frequency converter 10 to adjust the processing capacity of the compressor in time, the backflow pipeline 11 and the frequency converter 10 are used to adapt to the wellhead gas flow changes in different periods, and the reciprocating compressor 42 is designed to have multiple compression cylinders and two pressure level inlet systems at the same time to meet the conditions of simultaneous production of different wellheads of a platform.

[0045] The high-pressure and low-pressure two inlet points are designed to meet the simultaneous production of multiple wells of a platform, and the single inlet can enter different systems after the pressure changes in different periods to improve the production efficiency and save energy.

[0046] Further, the separator 2 further comprises a high-pressure separator 2b, and the natural gas enters the separator 2 through the wellhead connecting pipe 1, wherein the natural gas with a pressure less than or equal to 3 MPa enters the low-pressure separator 2a, and the natural gas with a pressure greater than or equal to 3 MPa enters the high-pressure separator 2b, wherein the natural gas with a pressure equal to 3 MPa enters the low-pressure separator 2a, is pressurized by the screw compressor 41, and then directly enters the natural gas pipeline 6 without entering the reciprocating compressor 42, and the natural gas with a pressure equal to 25 MPa directly enters the dehydration pry 5 without passing through the screw compressor 41 and the reciprocating compressor 42.

[0047] In actual application, the high-pressure and low-pressure two inlet points are designed, and the process of the natural gas with a pressure equal to 3.0 MPa directly entering the natural gas pipeline 6 and the natural gas with a pressure equal to 25.0 MPa directly entering the dehydration pry 5 or the tank car pipeline 7 is designed, the natural gas is directly compressed by the stratum energy or the pipeline, and the energy consumption is saved.

[0048] As shown in Figures 3-8 Fig. 1, the separator 2 is connected with an inlet pipe 21, the surface of the separator 2 is provided with a sealing door 22, the top of the separator 2 is connected with an exhaust pipe 12, and the inner cavity of the separator 2 is sequentially provided from top to bottom with an oil discharge cylinder 15, a filter screen 14 and an aeration pipe 13. The oil discharge cylinder 15 penetrates the bottom of the separator 2, the filter screen 14 is located outside the oil discharge cylinder 15, and the filter screen 14 is provided with an auxiliary mechanism 16.

[0049] It should be noted that the natural gas contains not only the dirty oil and dirty water, but also a small amount of sand impurities. When the dirty oil and dirty water are separated, the dirty oil, dirty water and impurities are all located in the separator 2. The impurities are easy to attach the dirty oil. The impurities sink in the water bottom. The dirty oil attached to the surface of the impurities cannot be separated and discharged. If the impurities are directly discharged together with the dirty oil attached to the surface of the impurities, the environmental pollution is caused and the collection amount of the dirty oil is reduced. At present, the heating method is generally used to separate the impurities and the dirty oil. The impurities in the water are heated, so that the dirty oil attached to the surface of the impurities is separated from the impurities, thereby the effect of separating the impurities and the dirty oil is achieved. However, the water vapor is generated when the water is heated. The generated water vapor may be discharged with the natural gas, thereby the purity of the natural gas is reduced.

[0050] In actual application, a part of water is injected into the separator 2 in advance, so that the dirty oil cannot float up due to the small amount of water contained in the natural gas. Meanwhile, a part of the pressurized natural gas is introduced into the aeration pipe 13. When the natural gas is separated, the natural gas enters into the separator 2 through the gas inlet pipe 21. Due to the centrifugal force, the dirty oil, dirty water and impurities in the natural gas drop to the bottom of the inner cavity of the separator 2. The natural gas is discharged through the gas outlet pipe 12. The dirty oil slowly floats on the water surface. The impurities sink in the water bottom. The water is aerated through the aeration pipe 13, so that the bubbles are generated in the water. The bubbles slowly rise. The bubbles contact the dirty oil on the surface of the impurities in the rising process. Due to the surface activity and viscosity of the dirty oil, the bubbles may be adsorbed on the surface of the dirty oil, so that the dirty oil is slowly separated from the impurities. Meanwhile, the existence of the bubbles increases the average density of the water. The buoyancy of the impurities with the original large density is increased, so that the impurities slowly float up. In the floating process, the bubbles are adsorbed on the surface of the dirty oil, so that the dirty oil is slowly separated from the impurities. The separated impurities slowly sink. In addition, the bubbles cause the flow and disturbance of the water. The disturbance of the water flow helps to break the adhesion between the dirty oil and the impurities, so that the dirty oil is more easily driven by the bubbles to float up, thereby the separation efficiency of the dirty oil and the impurities is improved. The bubbles break when rising to the water surface. The natural gas in the bubbles is discharged through the gas outlet pipe 12. The separation mode of the dirty oil and the impurities does not easily affect the purity of the natural gas.

[0051] The pressurized natural gas is introduced into the separator 2 through the aeration pipe 13, so that the natural gas can be separated again, thereby the purity of the finally output natural gas is improved.

[0052] Further, the auxiliary mechanism 16 comprises:

[0053] The rotating rod 161 is rotatably installed in the gas outlet pipe 12. The impeller 162 is fixed on the periphery of the rotating rod 161.

[0054] A plurality of upper cleaning brushes 166 and a plurality of lower cleaning brushes 167 are arranged on the outer side of the circular ring 165, the plurality of upper cleaning brushes 166 are arranged above the filter screen 14, and the plurality of lower cleaning brushes 167 are arranged below the filter screen 14.

[0055] A plurality of upper cleaning brushes 166 and a plurality of lower cleaning brushes 167 are arranged on the outer side of the circular ring 165, the plurality of upper cleaning brushes 166 are arranged above the filter screen 14, and the plurality of lower cleaning brushes 167 are arranged below the filter screen 14.

[0056] Further, the opposite sides of the adjacent two upper cleaning brushes 166 are provided with baffles 168.

[0057] It should be noted that the bubbles will drive the impurities to move upwards when the bubbles float, and the impurities are easy to contact with the dirty oil floating on the water surface after moving upwards, so that the dirty oil is also attached to the surface of the impurities.

[0058] In actual application, when the natural gas is discharged from the exhaust pipe 12, the flowing natural gas drives the impeller 162 to rotate, so that the rotating rod 161 rotates, the rotating rod 161 drives the circular ring 165 to rotate through the fixed plate 163 and the plurality of connecting plates 164, so that the plurality of upper cleaning brushes 166 rotate around the rotating rod 161, and the upper cleaning brushes 166 will collide with the impurities floating upwards when rotating, so that the impurities are separated from the dirty oil attached to the surface of the impurities after being impacted, and the impurities are effectively prevented from continuing to move upwards, and the impurities are effectively prevented from re-attaching the dirty oil on the surface of the impurities; meanwhile, the baffles 168 on both sides of the upper cleaning brushes 166 will block the impurities when the upper cleaning brushes 166 rotate, so as to further prevent the impurities from continuing to move upwards, and further prevent the impurities from re-attaching the dirty oil on the surface of the impurities.

[0059] During the rotation of the upper cleaning brushes 166, the upper cleaning brushes 166 clean the surface of the impurities, so as to accelerate the separation of the dirty oil and the impurities.

[0060] During the cleaning of the impurities by the upper cleaning brushes 166, the impurities may block the filter screen 14, at this time, the lower cleaning brushes 167 clean the bottom of the filter screen 14, effectively preventing the impurities from blocking the filter screen 14, and the lower cleaning brushes 167 can also clean the surface of the impurities, further accelerating the separation of the dirty oil and the impurities.

[0061] Further, the oil discharge cylinder 15 comprises an inner cylinder and an outer cylinder, a plurality of partition plates 152 are arranged between the inner cylinder and the outer cylinder, a discharge chamber 151 is formed between adjacent two partition plates 152, a plurality of through holes 153 are formed on the outer periphery of the oil discharge cylinder 15, the plurality of through holes 153 coincide with the positions of the plurality of partition plates 152, and a sealing cover 155 is arranged on the top of the outer cylinder.

[0062] Further, the oil discharge cylinder 15 is provided with a plurality of oil inlet pipes 154 penetrating the periphery of the oil discharge cylinder 15, the oil inlet pipes 154 are arranged downwardly and obliquely from the outside of the oil discharge cylinder 15 to the inside of the oil discharge cylinder 15, the inner side of the connecting plate 164 is an inclined surface and is inclined to the rotating direction of the rotating rod 161.

[0063] In actual application, the oil is attached to the water surface, part of the oil is located in the inner cylinder and part of the oil is located outside the outer cylinder, when the water level is higher than the highest part of the oil discharge cylinder 15, the oil floating on the water surface will enter the discharge chamber 151 and be discharged, and finally enter the oil tank 3; when the water level drops, the oil not discharged will move downward, and the oil will slowly enter the inner cylinder from the oil inlet pipe 154, and because the area where the oil exists in the inner cylinder is small, the oil in the inner cylinder is more likely to enter the discharge chamber 151 and be discharged, so that the oil discharge efficiency is improved.

[0064] When the rotating rod 161 rotates, the connecting plate 164 rotates around the rotating rod 161, because the inner side of the connecting plate 164 is an inclined surface, the connecting plate 164 stirs the water to flow reversely to the oil inlet pipe 154, so that the oil attached to the water surface is more likely to enter the oil inlet pipe 154, further improving the oil discharge efficiency.

[0065] Further, the liquid level sensor 18 is installed on the inner wall of the separator 2, the liquid level sensor 18 is at the same horizontal plane as the top of the oil discharge cylinder 15, the drain pipe 17 is installed on the separator 2, the drain pipe 17 is located between the aeration pipe 13 and the filter screen 14, the electromagnetic valve is installed on the drain pipe 17, and the liquid level sensor 18 and the electromagnetic valve are connected to the external control unit.

[0066] It should be noted that if the water level in the separator 2 always rises, the water in the separator 2 will be discharged into the oil tank 3 together with the oil, so that the oil contains water, increasing the subsequent processing cost of the oil.

[0067] In one case of the embodiment, the external control unit can be a computer terminal, the liquid level sensor 18 transmits a signal to the external control unit, and the external control unit controls the opening and closing of the electromagnetic valve according to the signal.

[0068] In actual application, when the water level in the separator 2 reaches the liquid level sensor 18, the liquid level sensor 18 transmits a signal to the external control unit, the external control unit controls the electromagnetic valve to open, so that the water in the separator 2 is discharged, the opening time of the electromagnetic valve is limited within a range, so as to avoid that the water in the separator 2 is discharged too much to cause the oil to be unable to be discharged for a long time, when the opening time of the electromagnetic valve is over, the electromagnetic valve is closed, and the water level continues to rise, so that the oil can be discharged; in this way, it is effectively avoided that the water increases the subsequent processing cost of the oil together with the oil.

[0069] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A system for recovery of vented natural gas from a drained oil and gas well, comprising a wellhead connection pipe (1), a slop tank (3), a dehydration skid (5), a natural gas pipeline (6) and a tank car pipeline (7), characterized in that, The system also comprises: A compressor (4) comprising a screw compressor (41) and a reciprocating compressor (42) connected in series, and the screw compressor (41) is located in the front end of the intake; A separator (2) connected between the compressor (4) and the wellhead connecting pipe (1), and the separator (2) is connected with the dirty oil tank (3); The separator (2) is connected with an air inlet pipe (21) on the periphery, a sealing door (22) is installed on the surface of the separator (2), an exhaust pipe (12) is connected through the top of the separator (2), an oil discharge cylinder (15), a filter screen (14) and an aeration pipe (13) are installed in the inner cavity of the separator (2) from top to bottom, the oil discharge cylinder (15) penetrates through the bottom of the separator (2), the filter screen (14) is located outside the oil discharge cylinder (15), and an auxiliary mechanism (16) is installed on the filter screen (14); The auxiliary mechanism (16) comprises: A rotating rod (161) rotatably installed in the exhaust pipe (12), and an impeller (162) is fixed on the periphery of the rotating rod (161); A circular ring (165) is fixed on the bottom of the rotating rod (161), a fixed plate (163) is arranged on the bottom of the rotating rod (161), a plurality of connecting plates (164) are arranged on the bottom of the fixed plate (163), a circular ring (165) is arranged on the bottom of the connecting plates (164), the circular ring (165) is located outside the oil discharge cylinder (15), and the outer surface of the circular ring (165) is attached to the inner side of the filter screen (14); An upper cleaning brush (166) and a lower cleaning brush (167) are arranged on the outer side of the circular ring (165), a plurality of upper cleaning brushes (166) are arranged above the filter screen (14), and a plurality of lower cleaning brushes (167) are arranged below the filter screen (14).

2. The system for recovery of vented natural gas from a draining oil and gas well according to claim 1, characterized in that, The separator (2) comprises a low-pressure separator (2a) and a high-pressure separator (2c), the gas inlet end of the screw compressor (41) is connected with the low-pressure separator (2a), the low-pressure separator (2a) is connected with the wellhead connecting pipe (1), the low-pressure separator (2a) is connected with the dirty oil tank (3), the gas inlet end of the screw compressor (41) is provided with a slide valve (411), the output end of the screw compressor (41) is provided with a frequency controller (10), the gas outlet end of the screw compressor (41) is connected with an air cooler (8), the gas outlet end of the air cooler (8) is connected with the high-pressure separator (2c), the gas outlet end of the air cooler (8) is also connected with a backflow pipeline (11), the end of the backflow pipeline (11) is connected with the gas inlet end of the screw compressor (41), the high-pressure separator (2c) is connected with the dirty oil tank (3), the gas outlet end of the high-pressure separator (2c) is connected with a reciprocating compressor (42), the output end of the reciprocating compressor (42) is provided with another frequency controller (10), the gas outlet end of the reciprocating compressor (42) is connected with another air cooler (8), the gas outlet end of the air cooler (8) is connected with a buffer tank (9), the gas outlet end of the air cooler (8) is also connected with another backflow pipeline (11), the end of the backflow pipeline (11) is connected with the gas inlet end of the reciprocating compressor (42), and the gas outlet end of the buffer tank (9) is connected with a dehydration pry (5).

3. The system for recovery of vented natural gas from a draining oil and gas well according to claim 2, characterized in that, The separator (2) further comprises a high-pressure separator (2b), and natural gas enters the separator (2) through the wellhead connecting pipe (1), wherein natural gas with a pressure less than or equal to 3 MPa enters the low-pressure separator (2a), and natural gas with a pressure greater than or equal to 3 MPa enters the high-pressure separator (2b), wherein natural gas with a pressure equal to 3 MPa enters the low-pressure separator (2a), is pressurized by the screw compressor (41), and then directly enters the natural gas pipeline (6) without entering the reciprocating compressor (42), and natural gas with a pressure equal to 25 MPa directly enters the dehydration pry (5) without passing through the screw compressor (41) and the reciprocating compressor (42).

4. The system for recovery of vented natural gas from a draining oil and gas well of claim 1, wherein, Opposite sides of adjacent two upper cleaning brushes (166) are provided with baffles (168).

5. The system for recovery of vented natural gas from a draining oil and gas well of claim 1, wherein, The oil discharge cylinder (15) comprises an inner cylinder and an outer cylinder, a plurality of partitions (152) are arranged between the inner cylinder and the outer cylinder, a discharge cavity (151) is formed between adjacent two partitions (152), a plurality of through holes (153) are formed in the periphery of the oil discharge cylinder (15), the positions of the plurality of through holes (153) coincide with those of the plurality of partitions (152), and a sealing cover (155) is arranged at the top of the outer cylinder.

6. The system for recovery of vented natural gas from a draining oil and gas well according to claim 5, characterized in that, A plurality of oil inlet pipes (154) penetrate the periphery of the oil discharge cylinder (15), the oil inlet pipes (154) are inclined downward from the outside of the oil discharge cylinder (15) to the inside of the oil discharge cylinder (15), the inner side of the connecting plate (164) is an inclined surface and is inclined toward the rotation direction of the rotating rod (161).

7. The system for recovery of vented natural gas from a draining oil and gas well of claim 1, wherein, The liquid level sensor (18) is installed on the inner wall of the separator (2), and is at the same level as the top of the oil discharge cylinder (15). A drain pipe (17) is installed on the separator (2) and is located between the aeration pipe (13) and the filter screen (14). An electromagnetic valve is installed on the drain pipe (17). The liquid level sensor (18) and the electromagnetic valve are connected to the external control unit.

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