Carbon dioxide foam injection device for oil displacement of oil well

Abstract

The invention relates to the technical field of oil well displacement equipment, in particular to a carbon dioxide foam injection device for oil well displacement. The device comprises a Christmas tree and a foaming tank, a centrifugal cylinder is arranged in the foaming tank, a hydraulic rod is arranged at the top of the foaming tank, a foam injection device is arranged at the bottom of the foaming tank, an air inlet pipe is communicated with the outer side of the foaming tank, a foam cavity is formed between the centrifugal cylinder and the foaming tank, a liquid inlet is formed in the bottom of the centrifugal cylinder, and a liquid return plate is slidably arranged on the outer side of the liquid inlet. A liquid return plate is arranged in the centrifugal cylinder, thrown foam liquid is guided into the centrifugal cylinder through the liquid inlet to be recycled, an adjusting mechanism and a valve mechanism are arranged above the liquid return plate, the adjusting mechanism is located between the centrifugal cylinder and the liquid return plate, and a stirring cavity is formed between the valve mechanism and the liquid return plate. And when the baffle moves downwards, the baffle is used for pressing air in the stirring cavity and the bubble channel into the centrifugal barrel, so that the air in the centrifugal barrel is reversely discharged from the small holes, and foams are prevented from entering the centrifugal barrel.

Description

Technical Field

[0001] The present invention relates to the technical field of oil well oil displacement equipment, and specifically, to a carbon dioxide foam injection device for oil well oil displacement. Background Art

[0002] Carbon dioxide foam is produced by mixing carbon dioxide gas and foam liquid and then foaming. During the process of oil well exploitation, injecting carbon dioxide foam for oil displacement can improve the oil production efficiency and at the same time achieve carbon dioxide emission reduction.

[0003] Currently, when using a foam injection device, the quantity of carbon dioxide foam has a significant impact on the oil production efficiency. However, in existing carbon dioxide foam injection devices, carbon dioxide and foaming liquid are circulated and mixed for foaming. In Chinese Patent Publication No.: CN113107440B, a well carbon dioxide foam injection device is proposed. It drives the active pulley to rotate through the output end of the motor, and then, under the cooperation of the transmission belt and the driven pulley, the driven pulley rotates, driving the centrifugal cylinder to rotate, generating centrifugal force, so that the foam liquid in the centrifugal cylinder is thrown out under the action of the centrifugal force. The carbon dioxide entering from the outside is evenly sprayed around the centrifugal cylinder through the air jetting member and premixed with the thrown-out foam liquid to improve the mixing degree, thus solving the problem in the prior art that the foaming rate of the injection device is low and affects the oil displacement effect.

[0004] Since the foam generated during the foaming process will slide along the outer wall of the centrifugal cylinder, and there are several small holes on the centrifugal cylinder, the following problems will occur. When the foam contacts the small holes, due to the surface tension at the edge of the small holes being different from that of other parts of the foam, this difference will cause the foam to move towards the direction with smaller surface tension (i.e., the inner side of the small holes), making the foam to be injected flow into the centrifugal cylinder, so the quantity of the foam to be injected will be reduced. Summary of the Invention

[0005] The present invention provides a carbon dioxide foam injection device for oil well oil displacement. When the baffle moves downward, the air in the stirring chamber and the bubble channel is pressed into the centrifugal cylinder to form an air flow from the inside to the outside in the small holes of the centrifugal cylinder, which plays a restrictive role on the foam, thus solving the problem raised in the above background art, that is: The foam to be injected will slide from the outside of the small holes of the centrifugal cylinder to the inside of the small holes, resulting in a reduction in the quantity of the foam to be injected.

[0006] To achieve the above object, the carbon dioxide foam injection device for oil well oil displacement includes a Christmas tree, a foaming tank, a centrifugal cylinder, and a hydraulic rod. The foaming tank is provided with a foam injection device and an air inlet pipe; A foam chamber is formed between the centrifugal cylinder and the foaming tank. A liquid inlet is provided at the bottom of the centrifugal cylinder. A liquid return plate is slidably arranged outside the liquid inlet. The liquid return plate is used to guide the foamed liquid thrown out into the centrifugal cylinder through the liquid inlet for recycling when the centrifugal cylinder rotates. An adjusting mechanism and a valve mechanism are arranged above the liquid return plate. The adjusting mechanism is located between the centrifugal cylinder and the liquid return plate. A stirring chamber is formed between the valve mechanism and the liquid return plate. When the centrifugal cylinder moves upward, the adjusting mechanism guides the foam in the stirring chamber upward to the valve mechanism, increasing the amount of foam in the foam chamber. When the centrifugal cylinder moves downward, the valve mechanism cuts off the stirring chamber from the foam chamber, enabling the adjusting mechanism to press the air in the stirring chamber into the centrifugal cylinder to prevent the foam in the foam chamber from entering the centrifugal cylinder.

[0007] The liquid inlet is arranged on the centrifugal cylinder away from the inner wall of the centrifugal cylinder. A limiting plate fixedly connected to the liquid return plate is slidably arranged outside the liquid inlet. A liquid return port corresponding to the liquid inlet is provided on the limiting plate.

[0008] Under normal conditions, the liquid return port and the liquid inlet are in a coincident state for the thrown-out foamed liquid to flow back into the centrifugal cylinder. When the liquid inlet and the liquid return port are misaligned, the limiting plate is used to restrict the foamed liquid from being thrown out of the liquid inlet, and the centrifugal cylinder restricts the foamed liquid in the stirring chamber from flowing back, causing the liquid level of the foamed liquid in the stirring chamber to rise.

[0009] The valve mechanism includes an outer valve plate fixedly arranged inside the foaming tank and an inner valve plate that fits with the outer valve plate. The inner valve plate is rotatably connected to the outer valve plate and the centrifugal cylinder respectively. Shunt holes are provided on both the inner valve plate and the outer valve plate. Under normal conditions, the shunt holes on the inner valve plate and the outer valve plate are in a misaligned state to restrict the foam in the foam chamber from sliding into the stirring chamber.

[0010] In the above technical solution, mainly the foamed liquid inside the centrifugal cylinder is thrown out during the working process of the centrifugal cylinder. By aligning the shunt holes on the inner valve plate and the outer valve plate, the thrown-out foamed liquid is realized to flow back into the centrifugal cylinder, enabling the foamed liquid to be used multiple times, saving raw materials. And when the shunt holes on the inner valve plate and the outer valve plate are misaligned, the inner valve plate and the outer valve plate block the foam sliding into the stirring chamber and guide the foam into the foam injection device to improve the oil displacement effect.

[0011] The inner side of the inner valve plate is bent upward to form an inner sleeve ring, and the inner side of the outer valve plate is bent upward to form an outer sleeve ring. An air bubble channel for the foam in the stirring chamber to slide into the foam chamber is formed between the inner sleeve ring and the centrifugal cylinder.

[0012] One end of the baffle away from the centrifugal cylinder fits with the inner sleeve ring. When the baffle moves downward, the baffle is used to press the air in the stirring chamber and the air bubble channel into the centrifugal cylinder, enabling the air in the centrifugal cylinder to be discharged reversely from the small holes to prevent the foam from entering the centrifugal cylinder.

[0013] In the above technical solution, when the baffle is reset, the baffle is moved in the bubble channel, and the diverter hole on the inner valve plate and the diverter hole on the outer valve plate are in an offset state. The baffle presses the air in the stirring chamber into the centrifugal cylinder, and the air is discharged from the inside of the small hole to the outside, thereby blocking the external foam to limit the entry of foam.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. When the baffle moves down, the diverter hole on the inner valve plate and the diverter hole on the outer valve plate are in a misaligned state. The baffle is used to press the air in the stirring chamber and the bubble channel into the centrifugal cylinder, so that the air in the centrifugal cylinder is discharged in the reverse direction from the small hole to limit the foam from entering the centrifugal cylinder.

[0015] When the diverter holes on the inner valve plate and the outer valve plate are in a conducting state, the ejected foam liquid can flow back into the centrifugal cylinder through these conducting diverter holes. This design allows the foam liquid to be recycled, improves resource utilization, and reduces foam liquid waste. 3. In the process of the diversion hole changing from conduction to dislocation, the inner valve plate and the outer valve plate play an intercepting role, preventing the foam from continuing to flow along the original path. At the same time, they guide the foam into the bubble injection device, ensuring that the foam can be smoothly injected into the oil well by the bubble injection device, realizing the dual functions of foam liquid circulation and foam guidance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 This is a partial cutaway schematic diagram of the internal structure of the foaming tank of the present invention; Figure 3 This is a front view of the internal structure of the foaming tank and centrifugal cylinder of the present invention; Figure 4 This is a schematic diagram of the explosion structure of the hydraulic rod, centrifugal cylinder, and stirring rod of the present invention; Figure 5 For the present invention Figure 3 A in the figure shows the structural diagram; Figure 6 It is a schematic diagram of the partial cross-section structure of the foaming tank and the centrifugal cylinder of the present invention; Figure 7 This is a schematic diagram of the explosion structure of the outer valve plate, inner valve plate, and liquid return plate of the present invention; Figure 8 This is a schematic diagram of the explosion structure of the baffle and inner valve plate of the present invention; Figure 9 This is a schematic diagram of the explosion structure of the stirring rod and the vertical rod of the present invention.

[0017] The meaning of each number in the figure is: 100, Christmas tree; 101, foaming tank; 102, hydraulic rod; 103, intake pipe; 104, foam injection device; 105, through hole 110, centrifugal cylinder; 111, liquid inlet; 112, bubble channel 120, adjusting mechanism; 121, baffle; 122, guide ball 130, valve mechanism; 131, inner valve plate; 132, outer valve plate; 133, diversion hole; 134, arc spring; 135, guide groove 140, liquid return plate; 141, limit plate; 142, liquid return port 150, stirring rod; 151, vertical rod Detailed implementation mode

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] Aiming at the problem that during the sliding process of foam and foam liquid on the outer surface of the centrifugal cylinder 110, both slide from the outside to the inside of the small holes, resulting in a reduction in the amount of foam to be injected into the oil well, the present invention provides a carbon dioxide foam injection device for oil well flooding, see Figures 1 - 2 As shown, it includes a Christmas tree 100 and a foaming tank 101. The foaming tank 101 is arranged on an offshore oil well exploitation platform. The inside of the foaming tank 101 is provided with a centrifugal cylinder 110, and the centrifugal cylinder 110 has a number of small holes. The top of the foaming tank 101 is provided with a hydraulic rod 102 for controlling the lifting of the centrifugal cylinder 110. The bottom of the foaming tank 101 is fixedly provided with a foam injection device 104. The power of the centrifugal cylinder 110 comes from the driving device on the foaming tank 101. Therefore, during use, the foam liquid is first injected into the centrifugal cylinder 110 through a riser pipe penetrating the foaming tank 101. The top end of the riser pipe is rotatably connected to an external foam liquid delivery pipe. Then, the hydraulic rod 102 drives the flap rotatably connected to the riser pipe to move upward, so that the centrifugal cylinder 110 moves upward until the small holes correspond to the nozzles on the inner wall of the foaming tank 101. During this process, the driving device and the riser pipe are slidably connected in the vertical direction. When rotating, the driving device drives the riser pipe to rotate, and the centrifugal cylinder 110 rotates synchronously with the riser pipe. The foam liquid in the centrifugal cylinder 110 is thrown out from the small holes into the foam chamber (a foam chamber is formed between the centrifugal cylinder 110 and the foaming tank 101) to form foam; Combined with Figure 3 and Figure 4As shown, an intake pipe 103 for supplying air to the nozzles on the inner wall of the foaming tank 101 is connected to the outside of the foaming tank 101. While the foam liquid is being thrown out, the intake pipe 103 transports carbon dioxide gas to the nozzles, causing the thrown-out foam liquid to be preliminarily mixed with the carbon dioxide gas. When the centrifugal cylinder 110 stops rotating, an active agent is injected into the injection pipe at the top of the foaming tank 101 to improve the stability of the foam. Secondly, a liquid inlet 111 is provided at the bottom of the centrifugal cylinder 110. A liquid return plate 140 is slidably arranged outside the liquid inlet 111. The liquid return plate 140 is used to guide the thrown-out foam liquid through the liquid inlet 111 into the centrifugal cylinder 110 when the centrifugal cylinder 110 is rotating, so as to realize the multiple use of the foam liquid. An adjustment mechanism 120 and a valve mechanism 130 are arranged above the liquid return plate 140. The adjustment mechanism 120 is located between the centrifugal cylinder 110 and the liquid return plate 140. A stirring chamber is formed between the valve mechanism 130 and the liquid return plate 140. When the centrifugal cylinder 110 moves upward, the adjustment mechanism 120 guides the foam in the stirring chamber to the valve mechanism 130 to increase the amount of foam in the foam chamber. When the centrifugal cylinder 110 moves downward, the valve mechanism 130 cuts off the connection between the stirring chamber and the foam chamber, so that the adjustment mechanism 120 presses the air in the stirring chamber into the centrifugal cylinder 110 to use the airflow in the small holes to prevent the foam in the foam chamber from entering the centrifugal cylinder 110.

[0020] In specific implementation, considering that during the process of injecting the foam liquid into the centrifugal cylinder 110, there is a liquid inlet 111 at the bottom of the centrifugal cylinder 110. If too much foam liquid is injected, the foam liquid will flow out reversely from the liquid inlet 111. Therefore, on the basis of the above illustration and in combination with Figure 5 As shown, the liquid inlet 111 is arranged on the centrifugal cylinder 110 away from the inner wall of the centrifugal cylinder 110. Each time the injected foam liquid is lower than the lower edge of the liquid inlet 111. A limiting plate 141 fixedly connected to the liquid return plate 140 is slidably arranged outside the liquid inlet 111. A liquid return port 142 corresponding to the liquid inlet 111 is provided on the limiting plate 141. In this state, the liquid inlet 111 coincides with the liquid return port 142.

[0021] Since the foam liquid will splash on the outer wall of the centrifugal cylinder 110 and the inner wall of the foaming tank 101 after being thrown out, under the action of gravity and the valve mechanism 130, the foam liquid enters the stirring chamber, and at this time the liquid return port 142 coincides with the liquid inlet 111 to supply the thrown-out foam liquid to flow back into the centrifugal cylinder 110, so as to achieve the purpose of multiple use of the foam liquid and save raw materials.

[0022] In addition, when the liquid inlet 111 is misaligned with the liquid return port 142, the limiting plate 141 is used to prevent the foam liquid from being thrown out of the liquid inlet 111, and the centrifugal cylinder 110 restricts the backflow of the foam liquid in the stirring cavity, causing the liquid level of the foam liquid in the stirring cavity to rise. That is to say, during the upward movement of the centrifugal cylinder 110, the liquid inlet 111 and the liquid return port 142 change from coincidence to misalignment. When the centrifugal cylinder 110 stops moving upward, the states of the liquid inlet 111 and the liquid return port 142 are as Figure 6 shown, the liquid inlet 111 is blocked by the limiting plate 141, restricting the foam liquid inside the centrifugal cylinder 110 from being thrown out; Moreover, during the rotation of the centrifugal cylinder 110, since the limiting plate 141 blocks the liquid inlet 111, the foam liquid is dispersed under the action of force. Among them, due to factors such as surface tension and gas entrainment, a stable foam structure is formed, and these foams have the characteristics of gas-liquid mixture. Another part of the foam liquid does not completely form foam and still exists in the form of liquid. As for the appearance, there will be small bubbles on the surface of the foam liquid, and the appearance of the liquid presents a foam shape and gathers in the stirring cavity.

[0023] As described above, the entire circulation process of the foam liquid: First, the foam liquid is thrown out by the centrifugal cylinder 110 into the foam cavity and is initially mixed with carbon dioxide gas. Then, the foam liquid enters the stirring cavity above the liquid return plate 140 through the valve mechanism 130, and when the liquid return port 142 coincides with the liquid inlet 111, it flows back into the centrifugal cylinder 110 from the stirring cavity for the next use.

[0024] Next, on the basis of the above Figure 3 and in combination with Figure 7 and Figure 8 shown, the specific structure of the valve mechanism 130 will be publicly described. The valve mechanism 130 includes an outer valve plate 132 fixedly arranged on the inner side of the foaming tank 101, and an inner valve plate 131 attached to the outer valve plate 132. The inner valve plate 131 is rotatably connected to the outer valve plate 132 and the centrifugal cylinder 110 respectively. Shunt holes 133 are provided on both the inner valve plate 131 and the outer valve plate 132. Under normal conditions, the shunt holes 133 on the inner valve plate 131 and the shunt holes 133 on the outer valve plate 132 are in a misaligned state. In this way, when the foam liquid is thrown out and the centrifugal cylinder 110 returns downward, the inner valve plate 131 and the outer valve plate 132 can block the foam in the foam cavity, thereby restricting the foam in the foam cavity from sliding into the stirring cavity. On the other hand, a through hole 105 communicating with the foam injection device 104 is provided on the foaming tank 101. The through hole 105 is higher than the end of the outer valve plate 132 connected to the inner wall of the foaming tank 101 in the horizontal direction and is used to restrict the refluxed foam liquid from entering the foam injection device 104.

[0025] Specifically, during operation: when the centrifugal drum 110 drives the regulating mechanism 120 to move upward, the regulating mechanism 120 rotates by shifting the inner valve plate 131, so that the diverter holes 133 on the inner valve plate 131 and the outer valve plate 132 change from a misaligned state to an overlapping state. When the centrifugal drum 110 stops moving upward and starts working, the foam liquid that is thrown out slides onto the outer valve plate 132 and slides into the stirring chamber through the diverter holes 133. At this time, the liquid return port 142 is blocked, and the liquid level of the reflux foam liquid in the stirring chamber rises. When the liquid return port 142 coincides with the liquid inlet 111 again, the foam liquid in the stirring chamber flows back into the centrifugal drum 110. On the contrary, when the diversion holes 133 on the inner valve plate 131 and the outer valve plate 132 are misaligned, the foam in the foam cavity slides from the through hole 105 into the bubble injection device 104, or the foam and a small amount of foam liquid are extracted through the bubble injection device 104 and injected into the underwater oil well to improve the oil recovery effect.

[0026] Among them, in the foam liquid circulation stage: when the diverter holes 133 on the inner valve plate 131 and the outer valve plate 132 are in a conductive state, the ejected foam liquid can flow back into the centrifugal cylinder 110 through these conductive diverter holes 133. This design method allows the foam liquid to be used multiple times, improves resource utilization, and reduces foam liquid waste.

[0027] Foam guiding stage: During the process of the diversion hole 133 changing from conduction to dislocation, the inner valve plate 131 and the outer valve plate 132 play an intercepting role, preventing the foam from continuing to flow along the original path. At the same time, they guide the foam into the bubble injection device 104, ensuring that the foam can be smoothly injected into the oil well by the bubble injection device 104, thereby realizing the dual functions of foam liquid circulation and foam guidance.

[0028] In order to further increase the amount of foam that slides from the foam cavity into the foam injection device 104, Figure 6 Combined with Figure 9 As shown, a stirring rod 150 is provided in the stirring chamber, and a vertical rod 151 is slidably provided at one end of the stirring rod 150. The tops of the multiple vertical rods 151 are fixed between the centrifugal cylinder 110, and the other end of the stirring rod 150 extends to directly below the diverter hole 133. In this way, when the diverter holes 133 on the inner valve plate 131 and the outer valve plate 132 are in a conducting state, the foam liquid that is thrown out flows into the stirring chamber through the diverter hole 133, and relies on the stirring rod 150 to collide with the foam liquid flowing into the stirring chamber to generate more foam.

[0029] Since the inner side of the inner valve plate 131 is bent upward to form an inner ring, and the inner side of the outer valve plate 132 is bent upward to form an outer ring, a bubble channel 112 is formed between the inner ring and the centrifugal cylinder 110 for the foam in the stirring chamber to slide into the foam chamber. Then, when foam is generated in the stirring chamber, the regulating mechanism 120 is in a state away from the bubble channel 112, that is, the stirring chamber and the foam chamber in this state are connected through the bubble channel 112, and the return liquid port 142 is blocked by the centrifugal cylinder 110, and the diversion holes 133 on the inner valve plate 131 and the outer valve plate 132 coincide with each other. In this way, the foam in the stirring chamber can not only be discharged from the bubble channel 112 to the foam chamber, but also can be discharged back to the foam chamber from the diversion hole 133 (please refer to the foam movement path in this process). Figure 6 ), thereby increasing the amount of foam in the foam cavity, which helps to improve the oil displacement effect when injecting into the oil well.

[0030] Furthermore, as described above, the regulating mechanism 120 is used to rotate the inner valve plate 131 when the centrifugal cylinder 110 moves upward to control the opening and closing of the diverter hole 133. Figure 6 and Figure 8 As shown, the adjustment mechanism 120 includes a baffle 121 fixedly arranged on the outer wall of the centrifugal barrel 110, and a plurality of guide balls 122 fixedly arranged on the outer edge of the baffle 121. A guide groove 135 is provided on the inner wall of the inner ring at a position corresponding to the guide ball 122. The guide groove 135 is used to guide the sliding of the guide ball 122 so that the guide ball 122 slides along the track of the guide groove 135. On the other hand, one end of the baffle 121 away from the centrifugal barrel 110 is in contact with the inner ring. When the baffle 121 is detached from the bubble channel 112, the bubble channel 112 is connected to the foam chamber. When the baffle 121 moves downward, the baffle 121 is used to press the air in the stirring chamber and the bubble channel 112 into the centrifugal barrel 110, so that the air in the centrifugal barrel 110 is discharged in the reverse direction from the small hole to limit the foam from entering the centrifugal barrel 110.

[0031] Working principle: When the baffle 121 moves upward from the bubble channel 112, the guide ball 122 slides in the guide groove 135. During this process, since a plurality of arc springs 134 are elastically connected between the bottom of the inner valve plate 131 and the inner wall of the foaming tank 101, when the diverter holes 133 on the inner valve plate 131 and the outer valve plate 132 coincide with each other, the arc spring 134 is in an elongated state, wherein the elongated state is the initial state of the spring. The purpose of this is that when the guide ball 122 escapes from the guide groove 135, the guide groove 135 is located directly below the guide ball 122. On the contrary, when the diverter holes 133 on the inner valve plate 131 and the outer valve plate 132 are misaligned, the arc spring 134 is in a compressed state. In addition, when the baffle 121 moves downward to reset, the guide ball 122 on the baffle 121 first slides into the guide groove 135. At this time, the principle of the baffle 121 sliding in the bubble channel 112 is the same as that of the piston rod moving in the piston cylinder, which will not be elaborated here. Moreover, the guide ball 122 moves downward to first deflect the inner valve plate 131 to move in the reverse direction, causing the diversion hole 133 to change to a misaligned state. Then, the baffle 121 continues to move downward, and the diversion hole 133 remains in the misaligned state. When the liquid return port 142 gradually coincides with the liquid inlet 111, the air in the stirring chamber is pressed into the centrifugal cylinder 110, and the air is discharged from the small holes, thereby restricting the foam from entering the centrifugal cylinder 110. Among them, the air discharge trajectory can be referred to Figure 6 the arrows h1 to h2 in

[0032] That is to say, when the baffle 121 moves upward to disengage from the bubble channel 112 and moves upward as the foam increases, the guide ball 122 can play a role in restricting the upward moving foam, preventing the foam from sliding along the outer wall of the centrifugal cylinder 110 to the small holes, causing the foam in the bubble channel 112 to slide reversely into the centrifugal cylinder 110. Secondly, when the foam on the centrifugal cylinder 110 slides along the outer wall towards the baffle 121, the baffle 121 can guide the sliding foam to slide onto the outer valve plate 132, avoiding directly sliding into the stirring chamber.

[0033] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A carbon dioxide foam injection device for oil well oil displacement, comprising a Christmas tree (100), a foaming tank (101), a centrifugal cylinder (110) and a hydraulic rod (102). A foam injection device (104) and an air inlet pipe (103) are arranged on the foaming tank (101); It is characterized in that: A foam cavity is formed between the centrifugal cylinder (110) and the foaming tank (101). A liquid inlet (111) is opened at the bottom of the centrifugal cylinder (110). A liquid return plate (140) is slidably arranged outside the liquid inlet (111). The liquid return plate (140) is used for guiding the thrown-out foam liquid through the liquid inlet (111) into the centrifugal cylinder (110) for recycling when the centrifugal cylinder (110) rotates; An adjusting mechanism (120) and a valve mechanism (130) are arranged above the liquid return plate (140). The adjusting mechanism (120) is located between the centrifugal cylinder (110) and the liquid return plate (140). A stirring cavity is formed between the valve mechanism (130) and the liquid return plate (140); When the centrifugal cylinder (110) moves upward, it drives the adjusting mechanism (120) to guide the foam in the stirring cavity to the valve mechanism (130), increasing the amount of foam in the foam cavity. When the centrifugal cylinder (110) moves downward, it drives the valve mechanism (130) to cut off the stirring cavity from the foam cavity, so that the adjusting mechanism (120) presses the air in the stirring cavity into the centrifugal cylinder (110) to prevent the foam in the foam cavity from entering the centrifugal cylinder (110).

2. The carbon dioxide foam injection device for oil well oil displacement according to claim 1, characterized in that: The liquid inlet (111) is arranged on the centrifugal cylinder (110) far from the inner wall of the centrifugal cylinder (110). A limiting plate (141) fixedly connected with the liquid return plate (140) is slidably arranged outside the liquid inlet (111). A liquid return port (142) corresponding to the liquid inlet (111) is opened on the limiting plate (141).

3. The carbon dioxide foam injection device for oil well oil displacement according to claim 2, wherein: Under normal conditions, the liquid return port (142) and the liquid inlet (111) are in a coincident state for the thrown-out foam liquid to flow back into the centrifugal cylinder (110); When the liquid inlet (111) and the liquid return port (142) are misaligned, the limiting plate (141) is used to limit the foam liquid from being thrown out of the liquid inlet (111), and the centrifugal cylinder (110) limits the foam liquid in the stirring cavity from flowing back.

4. The carbon dioxide foam injection device for oil well oil displacement according to claim 1, characterized in that: The valve mechanism (130) includes an outer valve plate (132) fixedly arranged inside the foaming tank (101), and an inner valve plate (131) attached to the outer valve plate (132). The inner valve plate (131) is respectively rotatably connected to the outer valve plate (132) and the centrifugal cylinder (110); Diversion holes (133) are opened on both the inner valve plate (131) and the outer valve plate (132). Under normal conditions, the diversion holes (133) on the inner valve plate (131) and the diversion holes (133) on the outer valve plate (132) are in a misaligned state to limit the foam in the foam cavity from sliding into the stirring cavity.

5. The carbon dioxide foam injection device for oil well oil displacement according to claim 4, characterized in that: A through hole (105) communicated with the foam injection device (104) is opened on the foaming tank (101). The through hole (105) is higher than the end of the outer valve plate (132) connected to the inner wall of the foaming tank (101) in the horizontal direction and is used to limit the refluxed foam liquid from entering the foam injection device (104).

6. The carbon dioxide foam injection device for oil well oil displacement according to claim 4, wherein: A stirring rod (150) is arranged in the stirring cavity. One end of the stirring rod (150) is slidably provided with a vertical rod (151). A plurality of the vertical rods (151) are fixedly arranged between the top and the centrifugal cylinder (110). The other end of the stirring rod (150) extends to directly below the diversion hole (133) to impact the foam liquid flowing into the stirring cavity.

7. The carbon dioxide foam injection device for oil well oil displacement according to claim 4, characterized in that: The inner side of the inner valve plate (131) is bent upward to form an inner collar, and the inner side of the outer valve plate (132) is bent upward to form an outer collar. An air bubble channel (112) for the foam in the stirring cavity to slide into the foam cavity is formed between the inner collar and the centrifugal cylinder (110).

8. The carbon dioxide foam injection device for oil well oil displacement according to claim 7, characterized in that: The adjusting mechanism (120) includes a baffle (121) fixedly arranged on the outer wall of the centrifugal cylinder (110), and a number of guide balls (122) fixedly arranged on the outer edge of the baffle (121). A guide groove (135) is opened on the inner wall of the inner collar at a position corresponding to the guide ball (122). The guide groove (135) is used to guide the sliding of the guide ball (122) so that the guide ball (122) slides along the track of the guide groove (135).

9. The carbon dioxide foam injection device for oil well oil displacement according to claim 7, characterized in that: One end of the baffle (121) away from the centrifugal cylinder (110) is attached to the inner collar. When the baffle (121) moves downward, the baffle (121) is used to press the air in the stirring cavity and the air bubble channel (112) into the centrifugal cylinder (110), so that the air in the centrifugal cylinder (110) is discharged reversely from the small holes to limit the foam from entering the centrifugal cylinder (110).

10. The carbon dioxide foam injection device for oil well oil displacement according to claim 4, characterized in that: A number of arc springs (134) are elastically connected between the bottom of the inner valve plate (131) and the inner wall of the foaming tank (101); When the diversion holes (133) on the inner valve plate (131) and the outer valve plate (132) coincide, the arc springs (134) are in a stretched state; When the diversion holes (133) on the inner valve plate (131) and the outer valve plate (132) are misaligned, the arc springs (134) are in a compressed state.

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