Gas lift pressure reduction synchronizer

Abstract

The utility model discloses a gas lift depressurization synchronizer, which comprises a liquid separation tank, a liquid storage tank, a mixed transportation cylinder, a buffer tank and a gas lift cylinder, conveying pipelines are communicated and fixed between the liquid separation tank and the mixed transportation cylinder, between the mixed transportation cylinder and the buffer tank and between the buffer tank and the gas lift cylinder, and an outlet of the gas lift cylinder is connected with a gas lift outlet pipe. And the right side of the buffer tank is fixedly communicated with a mixed output outlet pipe. By arranging a series of structures, gas lifting and pressure reduction work can be integrated, personnel can flexibly select high pressure or low pressure according to use requirements conveniently, replacement in a dismounting and moving mode on site is not needed, the use flexibility is improved, and the cost is reduced. According to the liquid separation device, overflow storage can be conveniently carried out when more water is in the liquid separation tank, liquid stored in the liquid storage tank can be automatically conveyed back to be supplemented and utilized when less liquid is in the liquid separation tank, the waste phenomenon is reduced, the mode of automatically conveying back and utilizing the overflowing liquid is utilized, the automation degree is high, and people can conveniently use the liquid separation device.

Description

Technical Field

[0001] The utility model relates to the technical field of gas lift pressure reduction synchronization equipment, in particular to a gas lift pressure reduction synchronization device. Background Art

[0002] When injecting water to increase the pressure of an oil well, it is necessary to select high-pressure and low-pressure methods according to different situations. Currently, different skid-mounted cylinder compressors are used to increase the pressure. When replacing, the compressor needs to be shut down separately for replacement. Sometimes, due to space limitations on site, it may be necessary to dismantle and move the compressor for replacement. High-pressure and low-pressure cannot be integrated for flexible switching, and the flexibility of use is not ideal. In view of this, the present application proposes a gas lift pressure reduction synchronization device to solve the above problems. Utility Model Content

[0003] The utility model aims to provide a gas lift pressure reduction synchronization device to solve the problems raised in the above background technology.

[0004] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a gas lift pressure reduction synchronization device, including a liquid separation tank, a liquid storage tank, a mixed gas cylinder, a buffer tank and a gas lift cylinder, the liquid separation tank and the mixed gas cylinder, the mixed gas cylinder and the buffer tank, and the buffer tank and the gas lift cylinder are all connected and fixed with a delivery pipeline, the outlet of the gas lift cylinder is connected with a gas lift outlet pipe, the right side of the buffer tank is connected and fixed with a mixed output outlet pipe, the mixed output outlet pipe and multiple delivery pipelines are all provided with control valves, the top right side of the liquid separation tank is connected and fixed with an air intake pipe; the provided air intake pipe is used to connect to an external air supply device such as an air compressor to supply air to the inside of the liquid separation tank, and utilize gas pressurization to transport the liquid inside The mixed gas cylinder is used to compress and pressurize the gas and liquid to 2-10MPa and transport them to the buffer tank for buffering. The gas lift cylinder is used to compress and squeeze the gas and liquid after the initial pressurization to 25-35MPa again and transport the high-pressure gas and liquid through the gas lift outlet pipe. The mixed output outlet pipe is used to directly transport the low-pressure gas and liquid in the buffer tank that has only been compressed and pressurized once. The control valve is used to allow personnel to flexibly select high pressure or low pressure according to usage requirements. The high-pressure gas and liquid and the low-pressure gas and liquid can be flexibly selected to integrate the gas lift and pressure reduction work. That is, when high pressure is required, secondary compression and pressurization are used to form high pressure, and when pressure reduction or low pressure is required, single compression and pressurization are used to form low pressure;

[0005] The liquid storage tank is fixedly installed at the bottom of the liquid separation tank, and a one-way overflow water flow component is fixedly connected between the right top of the liquid separation tank and the right side of the top of the liquid storage tank. A first ultrasonic liquid level sensor is fixedly installed on the top of the liquid separation tank, and the detection end of the first ultrasonic liquid level sensor extends into the liquid separation tank. A second ultrasonic liquid level sensor with a detection end extending into the inside is fixedly installed on the right side of the top of the liquid storage tank. A PLC controller is fixedly installed on the right side of the liquid separation tank, and an air intake switching component connected and fixed to the top of the one-way overflow water flow component is installed on the air intake pipe. The first ultrasonic liquid level sensor, the second ultrasonic liquid level sensor and the air intake switching component are all electrically connected to the PLC controller. A water inlet valve and a one-way return water component are fixedly connected to the right side of the top of the liquid separation tank. An opening is provided on the inner wall of the bottom of the liquid storage tank. A groove is provided, and the bottom end of the one-way water return component extends into the groove. The one-way overflow water flow component is used for one-way overflow and storage in the liquid storage tank when the water in the liquid separation tank is more or higher than the overflow position. The first ultrasonic liquid level sensor and the second ultrasonic liquid level sensor are used to detect the liquid level values ​​in the liquid separation tank and the liquid storage tank respectively and transmit the corresponding liquid level values ​​to the PLC controller. The air intake switching component is used to automatically switch to supplying air to the inside of the one-way overflow water flow component and stop supplying air to the liquid separation tank under the control of the PLC controller when the liquid level in the liquid separation tank is lower than the preset value and the liquid level in the liquid storage tank is higher than the preset value. The gas is converted into passing into the liquid storage tank to pressurize the inside. The one-way water return component is used to automatically supply the stored liquid back to the liquid separation tank for reuse when the gas pressurization enters the liquid storage tank.

[0006] Preferably, the one-way overflow water flow assembly includes a first one-way valve connected and fixed on the right side of the liquid separation tank, and an L-shaped overflow pipe is connected and fixed between the right side of the first one-way valve and the right side of the top inner wall of the liquid storage tank.

[0007] Preferably, the air intake switching assembly includes a first solenoid valve installed on the air intake pipe, a second solenoid valve is connected and fixed between the bottom of the air intake pipe and the top of the L-shaped overflow pipe, and the second solenoid valve and the first solenoid valve are both electrically connected to the PLC controller.

[0008] Preferably, the one-way water return component includes a U-shaped tube connected and fixed on the right side of the top of the liquid separation tank, the bottom right end of the U-shaped tube is connected and fixed with a second one-way valve with the top as an outlet, the bottom end of the second one-way valve extends into the liquid storage tank and is connected and fixed with a vertical pipe, and the bottom end of the vertical pipe extends into the groove.

[0009] Preferably, the right side of the first one-way valve is an outlet.

[0010] Preferably, the second solenoid valve is located on the right side of the first one-way valve.

[0011] Preferably, the U-shaped pipe is located at the rear side of the air intake pipe.

[0012] Compared with the prior art, the beneficial effects of the utility model are:

[0013] 1. The gas lift and depressurization synchronization device can integrate gas lift and depressurization work by cooperating with the set liquid separation tank, mixed gas cylinder, buffer tank, gas lift cylinder, gas lift outlet pipe, mixed output outlet pipe, transmission pipeline and control valve, so that personnel can flexibly select high pressure or low pressure according to the use requirements, without the need to replace it on site by dismantling and moving, thus improving the flexibility of use and achieving the effect of synchronous application of gas lift and depressurization on one integrated device;

[0014] 2. The gas lift pressure reduction synchronization device, through the cooperation of the liquid separation tank, liquid storage tank, PLC controller, second ultrasonic liquid level sensor, first ultrasonic liquid level sensor, one-way overflow water flow component, air intake switching component and one-way water return component, can store overflow when there is more water in the liquid separation tank and automatically return the liquid stored in the liquid storage tank for replenishment when there is less liquid inside, thereby reducing waste. In addition, the overflow liquid is automatically returned for utilization, with a high degree of automation and convenient use for personnel.

[0015] The utility model is provided with a series of structures, which can integrate the gas lift and pressure reduction work, so that personnel can flexibly select high pressure or low pressure according to use requirements, and there is no need to replace it on site by dismantling and moving. The flexibility of use is improved, and it is convenient to overflow and store the water when there is more water in the liquid separation tank, and automatically return the liquid stored in the liquid storage tank for replenishment when there is less liquid inside, thereby reducing waste. In addition, the overflow liquid is automatically returned for utilization, with a high degree of automation, which is convenient for personnel to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an overall schematic diagram of the gas lift pressure reduction synchronization device proposed by the utility model;

[0017] Figure 2 It is a schematic diagram of the three-dimensional structure of the connection between the liquid separation tank and the liquid storage tank of the gas lift pressure reduction synchronization device proposed by the utility model;

[0018] Figure 3 This is a schematic diagram of the main cross-sectional structure of the connection between the liquid separation tank and the liquid storage tank of the gas lift pressure reduction synchronization device proposed by the utility model.

[0019] In the figure: 1. liquid separation tank; 101. mixed gas cylinder; 102. buffer tank; 103. gas lift cylinder; 104. gas lift outlet pipe; 105. mixed output outlet pipe; 106. delivery pipeline; 2. liquid storage tank; 3. first solenoid valve; 4. air inlet pipe; 5. U-shaped pipe; 6. second one-way valve; 7. vertical pipe; 8. groove; 9. first one-way valve; 10. L-shaped overflow pipe; 11. PLC controller; 12. second ultrasonic liquid level sensor; 13. second solenoid valve; 14. first ultrasonic liquid level sensor. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] like Figures 1 to 3 As shown, the gas lift pressure reduction synchronization device proposed in this embodiment includes a liquid separator 1, a liquid storage tank 2, a mixed gas cylinder 101, a buffer tank 102 and a gas lift cylinder 103. A delivery pipeline 106 is connected and fixed between the liquid separator 1 and the mixed gas cylinder 101, between the mixed gas cylinder 101 and the buffer tank 102, and between the buffer tank 102 and the gas lift cylinder 103. The outlet of the gas lift cylinder 103 is connected to a gas lift outlet pipe 104. The right side of the buffer tank 102 is connected and fixed with a mixed output outlet pipe 105. The mixed output outlet pipe 105 and multiple delivery pipes 106 are provided with control valves. The top right side of the liquid separator 1 is connected and fixed with an air intake pipe 4. The air intake pipe 4 is used to connect to an external air compressor and other air supply equipment to supply air to the inside of the liquid separator 1. The gas increase The internal liquid is transported to the mixed gas cylinder 101 under pressure. The mixed gas cylinder 101 is used to compress the gas and liquid to 2-10MPa and transport it to the buffer tank 102 for buffering. The gas lift cylinder 103 is used to compress and squeeze the gas and liquid after the initial pressurization to 25-35MPa again and transport the high-pressure gas and liquid through the gas lift outlet pipe 104. The mixed output outlet pipe 105 is used to directly transport the low-pressure gas and liquid in the buffer tank 102 that has only been compressed and pressurized once. The control valve is used to allow personnel to flexibly select high pressure or low pressure according to usage requirements. The high-pressure gas and liquid and the low-pressure gas and liquid can be flexibly selected to integrate the gas lift and pressure reduction work, that is, when high pressure is required, secondary compression and pressurization are used to form high pressure, and when pressure reduction or low pressure is required, single compression and pressurization are used to form low pressure;

[0022] The liquid storage tank 2 is fixedly installed at the bottom of the liquid separation tank 1, and a one-way overflow water flow component is fixedly connected between the right top of the liquid separation tank 1 and the right side of the top of the liquid storage tank 2. A first ultrasonic liquid level sensor 14 is fixedly installed on the top of the liquid separation tank 1, and the detection end of the first ultrasonic liquid level sensor 14 extends into the liquid separation tank 1. A second ultrasonic liquid level sensor 12 with a detection end extending into the interior thereof is fixedly installed on the right side of the top of the liquid storage tank 2. A PLC controller 11 is fixedly installed on the right side of the liquid separation tank 1, and an air intake switching component connected and fixed to the top of the one-way overflow water flow component is installed on the air intake pipe 4. The first ultrasonic liquid level sensor 14, the second ultrasonic liquid level sensor 12 and the air intake switching component are all electrically connected to the PLC controller 11. A water inlet valve and a one-way return water component are fixedly connected to the right side of the top of the liquid separation tank 1. The bottom inner wall of the liquid storage tank 2 A groove 8 is provided on the top, and the bottom end of the one-way water return component extends into the groove 8. The one-way overflow water flow component is used for one-way overflow storage to the liquid storage tank 2 when the water in the liquid separation tank 1 is more or higher than the overflow position. The first ultrasonic liquid level sensor 14 and the second ultrasonic liquid level sensor 12 are used to detect the liquid level values ​​in the liquid separation tank 1 and the liquid storage tank 2 respectively and transmit the corresponding liquid level values ​​to the PLC controller 11. The air intake switching component is used to automatically switch to supplying air to the one-way overflow water flow component when the liquid level in the liquid separation tank 1 is lower than the preset value and the liquid level in the liquid storage tank 2 is higher than the preset value, and stop supplying air to the liquid separation tank 1 under the control of the PLC controller 11. The gas is converted and passed into the liquid storage tank 2 to pressurize the inside. The one-way water return component is used to automatically supply the stored liquid to the liquid separation tank 1 for reuse when the gas pressurization enters the liquid storage tank 2.

[0023] Specifically, the one-way overflow water flow assembly includes a first one-way valve 9 connected and fixed on the right side of the liquid separator tank 1, the right side of the first one-way valve 9 is an outlet, and an L-shaped overflow pipe 10 is connected and fixed between the right side of the first one-way valve 9 and the right side of the top inner wall of the liquid storage tank 2; the first one-way valve 9 and the L-shaped overflow pipe 10 are arranged to cooperate with each other, and when there is more water in the liquid separator tank 1 or the fluctuation exceeds the overflow position of the first one-way valve 9, the liquid overflows into the liquid storage tank 2 through the first one-way valve 9 and the L-shaped overflow pipe 10 in turn for storage, so as to prevent the liquid from directly overflowing and seeping to the outside.

[0024] Furthermore, the air intake switching assembly includes a first solenoid valve 3 installed on the air intake pipe 4, and a second solenoid valve 13 is connected and fixed between the bottom of the air intake pipe 4 and the top of the L-shaped overflow pipe 10. The second solenoid valve 13 and the first solenoid valve 3 are both electrically connected to the PLC controller 11, and the second solenoid valve 13 is located on the right side of the first one-way valve 9; the first solenoid valve 3 and the second solenoid valve 13 are arranged to cooperate with each other, and the liquid level value for controlling the opening and closing of the first solenoid valve 3 and the second solenoid valve 13 is preset by the PLC controller 11. When the liquid level value inside the liquid separation tank 1 is lower than the preset value, the PLC controller 11 controls the first solenoid valve 3 to close and the second solenoid valve 13 to open. When there is no water inside the liquid storage tank 2 or the liquid level inside the liquid separation tank 1 exceeds the preset value, the PLC controller 11 controls the first solenoid valve 3 to open and the second solenoid valve 13 to close. In this way, when there is less liquid in the liquid separation tank 1, the first solenoid valve 3 is closed and the second solenoid valve 13 is opened, the gas supplied at this time is converted to enter the L-shaped overflow pipe 10 through the second solenoid valve 13, and then enters the liquid storage tank 2 to increase the pressure inside.

[0025] Furthermore, the one-way water return component includes a U-shaped tube 5 connected and fixed to the right side of the top of the liquid separator 1. The U-shaped tube 5 is located at the rear side of the air inlet pipe 4. The right end of the bottom of the U-shaped tube 5 is connected and fixed with a second one-way valve 6 with the top as an outlet. The bottom end of the second one-way valve 6 extends into the liquid storage tank 2 and is connected and fixed with a vertical pipe 7. The bottom end of the vertical pipe 7 extends into the groove 8. The U-shaped tube 5, the second one-way valve 6 and the vertical pipe 7 are arranged to cooperate. When gas is supplied into the liquid storage tank 2 for pressurization, the gas squeezes the liquid inside it. At this time, under the squeezing force, the liquid inside the liquid storage tank 2 The liquid is supplied into the U-shaped tube 5 in one direction through the vertical pipe 7 and the second one-way valve 6 in sequence, and then supplied back to the liquid separation tank 1 through the U-shaped tube 5. When the liquid level in the liquid separation tank 1 reaches the preset liquid level value or there is no liquid level value in the liquid storage tank 2, the PLC controller 11 controls the first solenoid valve 3 to open and the second solenoid valve 13 to close, stop supplying gas to the liquid storage tank 2, and switch back to supplying gas to the liquid separation tank 1 again, so as to achieve the effect of automatically returning the overflow collected in the liquid storage tank 2 for replenishment and utilization when there is less liquid in the liquid separation tank 1, with a high degree of automation and reduced waste.

[0026] The method of using the present embodiment is as follows: water is added into the liquid separator 1, the air inlet pipe 4 is connected to an external air compressor or other air supply equipment, the gas lift outlet pipe 104 and the mixed output outlet pipe 105 are connected to the wellhead equipment, the gas is sequentially supplied into the liquid separator 1 through the air inlet pipe 4 and the first solenoid valve 3, the internal liquid is transported to the mixed delivery cylinder 101 by gas pressurization, the mixed delivery cylinder 101 compresses the gas and liquid to 2-10MPa and transports them to the buffer tank 102 for buffering, when the control valve on the delivery pipeline 106 connected to the gas lift cylinder 103 is opened, the gas lift cylinder 103 is opened to compress and squeeze the gas and liquid after the initial pressurization to 25-35MPa again and pass through the gas lift outlet The pipe 104 transports high-pressure gas and liquid, and when low-pressure gas and liquid need to be transported, the control valve on the mixed output outlet pipe 105 is only needed to be opened to directly use the gas and liquid that have been compressed and buffered only once. By controlling the corresponding control valve, personnel can flexibly select high pressure or low pressure according to the use requirements. By using the flexible selection of high-pressure gas and liquid and low-pressure gas and liquid, gas lift and pressure reduction can be integrated into one, that is, when high pressure is required, secondary compression and pressure increase are used to form high pressure, and when pressure reduction or low pressure is required, single compression and pressure increase are used to form low pressure, so that the effect of simultaneous application of gas lift and pressure reduction on an integrated device is achieved, and there is no need to replace it on site by dismantling and moving, thereby improving the flexibility of use;

[0027] When in use, when there is more water in the liquid separation tank 1 or it is higher than the overflow position of the first one-way valve 9, the excess water in the liquid separation tank 1 overflows into the liquid storage tank 2 through the first one-way valve 9 and the L-shaped overflow pipe 10 for storage, so as to prevent the liquid from directly overflowing and seeping out to the outside and being wasted. The liquid level values ​​for opening and closing the first solenoid valve 3 and the second solenoid valve 13 are preset by the PLC controller 11 according to the use requirements. The first ultrasonic liquid level sensor 14 and the second ultrasonic liquid level sensor 12 respectively detect the liquid level values ​​in the liquid separation tank 1 and the liquid storage tank 2 and transmit them to the corresponding liquid level values ​​of the PLC controller 11. When the liquid level value inside the liquid separation tank 1 is lower than the preset value, the PLC controller 11 controls the first solenoid valve 3 to close and the second solenoid valve 13 to open. When there is no water in the liquid storage tank 2 or the liquid level in the liquid separation tank 1 exceeds the preset value, the PLC controller 11 controls the first solenoid valve 3 to open and the second solenoid valve 13 to close. In this way, when there is less liquid in the liquid separation tank 1, the PLC controls The device 11 controls the first solenoid valve 3 to close and the second solenoid valve 13 to open. At this time, the supplied gas is converted into entering the L-shaped overflow pipe 10 through the second solenoid valve 13, and then enters the liquid storage tank 2 to increase the pressure inside it. The gas squeezes the liquid inside the liquid storage tank 2. At this time, under the squeezing force, the liquid inside the liquid storage tank 2 is sequentially supplied to the U-shaped tube 5 through the vertical pipe 7 and the second one-way valve 6, and then returned to the liquid separation tank 1 through the U-shaped tube 5. When the liquid level in the liquid separation tank 1 reaches the preset liquid level value or there is no liquid level value in the liquid storage tank 2, the PLC controller 11 controls the first solenoid valve 3 to open and the second solenoid valve 13 to close, stop supplying gas to the liquid storage tank 2, and switch back to supplying gas to the liquid separation tank 1 again, so as to achieve overflow storage when there is more water in the liquid separation tank 1 and automatically return the liquid stored in the liquid storage tank 2 for replenishment and utilization when there is less liquid inside, thereby reducing waste. In addition, the overflow liquid is automatically returned for utilization by automation, which has a high degree of automation and is convenient for personnel to use.

[0028] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. Gas lift depressurization synchronization device, characterized by: The invention comprises a liquid separation tank (1), a liquid storage tank (2), a mixed gas cylinder (101), a buffer tank (102) and a gas lift cylinder (103); a delivery pipeline (106) is connected and fixed between the liquid separation tank (1) and the mixed gas cylinder (101), between the mixed gas cylinder (101) and the buffer tank (102), and between the buffer tank (102) and the gas lift cylinder (103); the outlet of the gas lift cylinder (103) is connected to a gas lift outlet pipe (104); the right side of the buffer tank (102) is connected and fixed with a mixed output outlet pipe (105); the mixed output outlet pipe (105) and the plurality of delivery pipelines (106) are provided with control valves; the top right side of the liquid separation tank (1) is connected and fixed with an air inlet pipe (4); The liquid storage tank (2) is fixedly mounted on the bottom of the liquid separation tank (1); a one-way overflow water flow assembly is fixedly connected between the top right side of the liquid separation tank (1) and the top right side of the liquid storage tank (2); a first ultrasonic liquid level sensor (14) is fixedly mounted on the top of the liquid separation tank (1); a detection end of the first ultrasonic liquid level sensor (14) extends into the liquid separation tank (1); a second ultrasonic liquid level sensor (12) is fixedly mounted on the top right side of the liquid storage tank (2); and a detection end of the second ultrasonic liquid level sensor (12) extends into the liquid separation tank (1). A PLC controller (11) is fixedly installed, an air intake switching assembly connected and fixed to the top of the one-way overflow water flow assembly is installed on the air intake pipe (4), the first ultrasonic liquid level sensor (14), the second ultrasonic liquid level sensor (12) and the air intake switching assembly are all electrically connected to the PLC controller (11), a water inlet valve and a one-way water return assembly are connected and fixed to the right side of the top of the liquid separation tank (1), a groove (8) is opened on the inner wall of the bottom of the liquid storage tank (2), and the bottom end of the one-way water return assembly extends into the groove (8).

2. The gas lift depressurization synchronization device according to claim 1, characterized in that: The one-way overflow water flow assembly comprises a first one-way valve (9) connected and fixed on the right side of the liquid separation tank (1), and an L-shaped overflow pipe (10) is connected and fixed between the right side of the first one-way valve (9) and the right side of the top inner wall of the liquid storage tank (2).

3. The gas lift depressurization synchronization device according to claim 2, characterized in that: The air intake switching assembly comprises a first solenoid valve (3) installed on an air intake pipe (4), a second solenoid valve (13) is connected and fixed between the bottom of the air intake pipe (4) and the top of the L-shaped overflow pipe (10), and the second solenoid valve (13) and the first solenoid valve (3) are both electrically connected to a PLC controller (11).

4. The gas lift depressurization synchronization device according to claim 1, characterized in that: The one-way water return assembly comprises a U-shaped tube (5) connected and fixed to the right side of the top of the liquid separation tank (1); the right end of the bottom of the U-shaped tube (5) is connected and fixed to a second one-way valve (6) with the top as an outlet; the bottom end of the second one-way valve (6) extends into the liquid storage tank (2) and is connected and fixed to a vertical tube (7); the bottom end of the vertical tube (7) extends into the groove (8).

5. The gas lift depressurization synchronization device according to claim 2, characterized in that: The right side of the first one-way valve (9) is an outlet.

6. The gas lift depressurization synchronization device according to claim 3, characterized in that: The second solenoid valve (13) is located on the right side of the first one-way valve (9).

7. The gas lift depressurization synchronization device according to claim 4, characterized in that: The U-shaped pipe (5) is located at the rear side of the air intake pipe (4).

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