Variable pitch helical air anchor

Abstract

The present application relates to the technical field of gas anchor, and more particularly to a variable-pitch spiral gas anchor. The variable-pitch spiral gas anchor comprises an anchor body, a sand prevention cylinder is installed on the lower side of the anchor body, the sand prevention cylinder is provided with sand prevention holes, a spiral piece is fixedly connected in the anchor body, a central pipe is fixedly connected to the middle part of the spiral piece and fixedly connected to the anchor body, the anchor body, the spiral piece and the central pipe cooperatively form a spiral channel, a separation cavity is arranged on the upper side of the spiral piece in the anchor body, the pitch of the lower side of the spiral piece is smaller than that of the upper side, the pitch of the upper side of the spiral piece gradually increases from bottom to top, and the central pipe is provided with exhaust holes which are spirally distributed and all located on the inner side of the spiral piece. The variable-pitch spiral gas anchor sets the pitch of the spiral piece so that the petroleum pushes the gas to the middle part, and the exhaust holes are used to discharge the gas in the spiral channel in advance, thereby reducing the amount of gas accumulated in the separation cavity and ensuring the smooth progress of the oil pumping process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas anchor, and particularly relates to a variable-pitch spiral gas anchor. BACKGROUND

[0002] In the process of oilfield exploitation, especially when mechanical oil extraction is carried out by using a pump, well fluid (i.e. fluid produced from an oil layer) is usually a gas-liquid mixed phase. If gas enters the pump, the pump efficiency will be reduced, gas locking, stroke loss and other problems will occur, and the efficiency and stability of the oil extraction system will be seriously affected. In order to reduce the influence of gas on the pump, a gas anchor is usually used as a downhole gas-liquid separation device. The core function of the gas anchor is to separate free gas as much as possible before the well fluid enters the pump.

[0003] In the prior art, a spiral gas anchor is a common gas-liquid separation device. The basic working principle of the spiral gas anchor is as follows: the spiral blade is used to guide the rotation of the well fluid, and the centrifugal force is used to make the liquid with a larger density tend to the pipe wall, and the gas with a smaller density is gathered in the center. The separated gas is discharged into the oil sleeve annulus through a special gas discharge channel, and the degassed liquid enters the suction inlet of the pump through the oil discharge port. However, when the proportion of gas in the oil-gas mixture is too high, the spiral blade can realize preliminary gas-liquid centrifugal separation, but the subsequent separation chamber has insufficient gas discharge capacity. The gas rises too fast in the separation chamber and cannot be discharged in time through the gas discharge channel, so that the gas accumulates at the top of the separation chamber to form a gas cap. The gas cap will press the liquid surface in the separation chamber, so that the liquid surface is lowered even below the height of the oil discharge port. Once the oil discharge port is exposed in the gas cap, the separated gas will directly enter the oil discharge channel instead of the designed gas discharge channel. This part of gas will finally be sucked into the pump together with the liquid, which affects the oil extraction process. In the process of oil extraction, oil will carry impurities such as sand. Long-term extraction will cause the sand to block the mesh of the sand prevention cylinder, thereby reducing the oil extraction efficiency. SUMMARY

[0004] The present application provides a kind of auxiliary exhaust variable-pitch spiral gas anchor, to solve the technical problems that the separation chamber on the existing spiral gas anchor cannot discharge gas in time when it handles oil-gas mixture with too high gas proportion, sand carried in oil blocks the mesh of sand prevention cylinder, which reduces the oil extraction efficiency.

[0005] The technical scheme of the present application is: a variable-pitch spiral air anchor, comprising an anchor body, a sand prevention cylinder is installed on the lower side of the anchor body, the sand prevention cylinder is provided with sand prevention holes, a spiral fin is fixedly connected in the anchor body, the middle part of the spiral fin is fixedly connected with a central pipe fixedly connected with the anchor body, the anchor body, the spiral fin and the central pipe cooperate to form a spiral channel, the upper side of the spiral fin in the anchor body is provided with a separation cavity, the anchor body is provided with an oil discharge port communicated with the separation cavity, the anchor body is provided with an oil discharge channel communicated with the oil discharge port, the anchor body is provided with an exhaust channel communicated with the central pipe, the central pipe is provided with an exhaust groove communicated with the separation cavity, the anchor body is provided with a reverse-horn-shaped flow guide surface near the exhaust groove, the pitch of the lower side of the spiral fin is smaller than that of the upper side, the pitch of the upper side of the spiral fin gradually increases from bottom to top, and the central pipe is provided with exhaust holes distributed in a spiral shape.

[0006] Further preferably, the hole diameter of the exhaust holes distributed in a spiral shape gradually increases from bottom to top.

[0007] Further preferably, the anchor body is provided with symmetrically distributed sealing cavities, a sealing plug is sealingly and slidingly connected in the sealing cavities, the sealing plug is fixedly connected with a sliding rod slidingly connected with the anchor body, the sliding rod is fixedly connected with a connecting plate, and the symmetrically distributed connecting plates are jointly fixedly connected with a circular ring slidingly connected with the sand prevention cylinder.

[0008] Further preferably, the diameter of the outer ring surface of the circular ring gradually decreases from the middle part to both sides.

[0009] Further preferably, the anchor body is fixedly connected with fixed rods symmetrically distributed and respectively located in the corresponding sealing cavities, the sliding rod is slidingly connected with the adjacent fixed rod, and a first spring is fixedly connected between the sliding rod and the anchor body and sleeved on the outer side of the adjacent fixed rod.

[0010] Further preferably, the symmetrically distributed sliding rods are jointly fixedly connected with a fixed ring, a tension spring is fixedly connected between the fixed ring and the sand prevention cylinder, and the sand prevention cylinder is slidingly connected with the anchor body.

[0011] Further preferably, the lower part of the anchor body is provided with symmetrically distributed through holes, one side of the sand prevention cylinder close to the fixed ring is provided with a shoulder part, a limiting rod for limiting the shoulder part is slidingly connected in the through hole of the anchor body, and a limiting piece is slidingly connected on the side of the through hole of the anchor body away from the shoulder part, and a second spring is fixedly connected between the limiting piece and the adjacent limiting rod.

[0012] Further preferably, the sliding rod is provided with a guide groove, the limiting piece is provided with a limiting part in the shape of a rectangle, and the limiting part of the limiting piece slides in the adjacent guide groove.

[0013] Further preferably, the limiting rod is provided with an inclined surface on the side close to the fixing ring, the shoulder portion is used for pressing the inclined surface of the limiting rod, and the elastic coefficient of the first spring is greater than the elastic coefficient of the second spring.

[0014] Further preferably, the guide groove is composed of vertical grooves and inclined grooves, the vertical grooves of the guide groove are located above the inclined grooves, and the distance between the inclined grooves is gradually increased from top to bottom.

[0015] Beneficial effects: the present application sets the pitch of the spiral piece to push the gas to the middle part of the oil, and cooperates with the exhaust hole to discharge the gas in the spiral channel in advance, reduces the amount of gas accumulated in the separation cavity, ensures the smooth progress of the oil pumping process, and the connecting plate drives the circular ring to move longitudinally to scrape off the sand isolated outside the sand prevention cylinder, ensures the flow of oil, and the diameter of the outer ring surface of the circular ring gradually decreases from the middle part to both sides, so that the scraped sand is guided away from the sand prevention cylinder, and the sand outside the sand prevention cylinder is scraped off, the elastic force of the release tension spring drives the sand prevention cylinder to move upward, so that the oil in the sand prevention cylinder performs backflushing operation on the sand prevention hole, ensures the smooth progress of the oil pumping process. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of the three-dimensional structure of the present application;

[0017] Figure 2 is a sectional view of the three-dimensional structure of the present application;

[0018] Figure 3 is a schematic diagram of the three-dimensional structure of the oil-gas interface a of the present application;

[0019] Figure 4 is a schematic diagram of the three-dimensional structure of the present application Figure 3 at A;

[0020] Figure 5 is a schematic diagram of the three-dimensional structure of the present application Figure 3 at B;

[0021] Figure 6 is a schematic diagram of the three-dimensional structure of the present application

[0022] 1-anchor, 11-helical channel, 111-separation cavity, 12-oil discharge port, 13-oil discharge channel, 14-gas discharge channel, 15-sealing cavity, 2-sand prevention cylinder, 21-shoulder, 3-helical blade, 4-central tube, 41-gas discharge groove, 42-gas discharge hole, 501-sealing plug, 502-sliding rod, 51-guide groove, 503-connection plate, 504-circular ring, 601-fixing rod, 602-first spring, 701-fixing ring, 702-tension spring, 801-limiting rod, 802-limiting piece, 803-second spring. DETAILED DESCRIPTION

[0023] The application will be further described below in connection with the embodiments shown in the drawings. Embodiment 1

[0024] The existing helical gas anchor separates the gas and oil separated by the helical blade through the separation cavity. When the proportion of gas is large, the gas cannot be discharged into the oil jacket annulus through the gas discharge channel in a short time, and the gas will occupy the upper part of the separation cavity, so that the outer oil level is lower than the oil discharge port, and the gas will be discharged into the oil discharge channel through the oil discharge port not blocked by the oil, and then into the subsequent oil pipe, affecting the oil pumping process.

[0025] A variable-pitch helical gas anchor, as shown in Figures 1-3 The anchor body 1 is installed at the lower end of the oil pipe, and the sand prevention cylinder 2 is installed at the lower side of the anchor body 1. In this embodiment, the connection between the sand prevention cylinder 2 and the anchor body 1 is considered as fixed connection, and the sand prevention cylinder 2 is provided with a sand prevention hole at the lower part. During the upstroke process, the oil-gas mixture at the well bottom enters the sand prevention cylinder 2 through the sand prevention hole of the sand prevention cylinder 2, and the sand in the oil-gas mixture is intercepted outside the sand prevention cylinder 2. The helical blade 3 is fixedly connected in the anchor body 1, and the central tube 4 is fixedly connected to the middle part of the helical blade 3 and the anchor body 1. The anchor body 1, the helical blade 3 and the central tube 4 cooperate to form a helical channel 11. The oil-gas mixture enters the anchor body 1 through the lower side and is guided along the helical channel 11 by the helical blade 3. Because the gas and oil in the oil-gas mixture have different densities, the centrifugal force of the gas during rotation is smaller than that of the oil, and the gas and oil are separated. The upper side of the helical blade 3 in the anchor body 1 is provided with a separation cavity 111, and the oil-gas interface of the rotating gas and oil in the separation cavity 111 is as shown in Figure 3The a shown in a is a cone surface placed in reverse, the oil outside liquid level is higher than the inside liquid level, the anchor body 1 is provided with an oil discharge port 12 communicated with the separation cavity 111, the anchor body 1 is provided with an oil discharge channel 13 communicated with the oil discharge port 12, the anchor body 1 is provided with an exhaust channel 14 communicated with the central tube 4, the central tube 4 is provided with an exhaust groove 41 communicated with the separation cavity 111, the gas rotating in the separation cavity 111 enters the exhaust channel 14 through the exhaust groove 41 upwards and is discharged into the oil jacket annulus, the oil rotating in the separation cavity 111 enters the oil discharge channel 13 through the oil discharge port 12 and flows upwards into the subsequent oil pipe, the position of the anchor body 1 close to the exhaust groove 41 is provided with an inverted horn-shaped flow guide surface for collecting the gas in the separation cavity 111, the pitch of the lower side of the helical blade 3 is smaller than that of the upper side, so that the oil-gas mixture has completed oil-gas separation at high speed at the lower side of the spiral channel 11, the pitch of the upper side of the helical blade 3 gradually increases from bottom to top, the separated gas and oil move upwards along the spiral channel 11, the rotating speed gradually decreases, the central tube 4 is provided with a spiral-shaped exhaust hole 42, the separated gas in the spiral channel 11 enters the central tube 4 through the exhaust hole 42 in advance, the diameter of the spiral-shaped exhaust hole 42 gradually increases from bottom to top, which is suitable for the characteristics that the pitch of the helical blade 3 increases and the gas content between adjacent rotating blades increases, so that more gas is discharged in the upper spiral channel 11.

[0026] The oil extraction is divided into upstroke and downstroke processes, in the upstroke process, the oil-gas mixture at the downhole passes through the sand prevention hole of the sand prevention cylinder 2 into the sand prevention cylinder 2, the sand in the oil-gas mixture is intercepted outside the sand prevention cylinder 2, the oil-gas mixture enters the anchor body 1 at the lower side and is guided along the spiral channel 11 by the helical blade 3, because the gas and oil in the oil-gas mixture have different densities, the centrifugal force suffered by the gas during rotation is smaller than that suffered by the oil, the gas and oil are separated, the oil gradually gathers outside the spiral channel 11 during the upward movement of the spiral channel 11, and the gas mainly gathers on the side of the spiral channel 11 close to the central tube 4, finally the separated gas and oil rotate into the separation cavity 111, the oil-gas interface of the gas and oil rotating in the separation cavity 111 is as shown in a. Figure 3 The a shown in a is a cone surface placed in reverse, the oil outside liquid level is higher than the inside liquid level, the gas rotating in the separation cavity 111 enters the exhaust channel 14 through the exhaust groove 41 upwards and is discharged into the oil jacket annulus, the oil rotating in the separation cavity 111 enters the oil discharge channel 13 through the oil discharge port 12 and flows upwards into the subsequent oil pipe.

[0027] In the process of the oil-gas mixture moving upward along the spiral channel 11, the pitch of the lower side of the spiral blade 3 is smaller than the pitch of the upper side, so that the oil-gas mixture has completed oil-gas separation at a high speed at the lower side of the spiral channel 11, and when entering the upper side of the spiral channel 11, the oil-gas mixture moves upward with the middle part being gas and the outer side being oil. After the gas and oil enter the upper side of the spiral channel 11, the rotation speed of the separated gas and oil decreases due to the gradually increasing pitch of the upper side of the spiral blade 3 from bottom to top, and the oil-gas interface a gradually flattens (the gradual flattening is only relative to the oil-gas interface of the high-speed rotating oil and gas, and in fact, the inclination angle of the oil-gas interface a only slightly decreases). In the process of the gradual flattening of the oil-gas interface a, the oil at the outer side will squeeze the gas at the middle part to make the gas enter the central pipe 4 through the exhaust hole 42, and part of the gas actively enters the central pipe 4 through the exhaust hole 42, thereby assisting the exhaust of the gas in the spiral channel 11. In addition, the pitch of the upper side of the spiral blade 3 is greater than the pitch of the lower side, so the diameter of the exhaust hole 42 arranged in a spiral shape is set to gradually increase from bottom to top, so that more gas is exhausted in the upper side of the spiral channel 11. By changing the pitch of the spiral blade 3, the oil pushes the gas to the middle part, and cooperates with the exhaust hole 42 to exhaust the gas in the spiral channel 11 in advance, thereby preventing most of the gas from accumulating in the separation cavity 111 and being discharged into the oil discharge channel 13 with the oil.

[0028] When the upstroke ends, the downstroke is performed. In the process of the downstroke, the oil no longer flows upward, and the separation speed of the gas and oil in the separation cavity 111 decreases. The gas only moves upward by using the characteristic that the density of the gas is less than the density of the oil. The gas continues to be discharged into the oil jacket annulus from the exhaust channel 14. When the downstroke ends, the above operation is continuously repeated. Example 2

[0029] In the process of oil extraction, the sand carried in the oil will block the sand prevention holes of the sand prevention cylinder, thereby causing the amount of oil entering the oil pipe to be small and the oil extraction efficiency to be low.

[0030] On the basis of example 1, a variable-pitch spiral gas anchor, like Figures 1-6As shown, the anchor body 1 is provided with two symmetrical sealing cavities 15, and a sealing plug 501 is slidingly connected in the sealing cavity 15. During the upstroke, the pressure in the anchor body 1 is reduced, and the pressure in the two sealing cavities 15 is reduced, so that the adjacent sealing plug 501 moves upward. The sealing plug 501 is fixedly connected with a sliding rod 502 (the sliding rod 502 is composed of two vertical rods with different lengths and a horizontal plate connecting the two vertical rods) which is slidingly connected with the anchor body 1. The upward movement of the sealing plug 501 allows the oil in the well to slowly flow upward through the sliding connection between the sliding rod 502 and the anchor body 1 into the adjacent sealing cavity 15, while limiting the longitudinal movement speed of the sealing plug 501. The sliding rod 502 is fixedly connected with a connecting plate 503, and the two connecting plates 503 are jointly fixedly connected with a circular ring 504 which is slidingly connected with the sand prevention cylinder 2. The diameter of the outer ring surface of the circular ring 504 gradually decreases from the middle to both sides. The two connecting plates 503 drive the circular ring 504 to longitudinally reciprocate to remove the sand of the sand prevention cylinder 2, so as to ensure the flow capacity of the oil. In addition, the diameter of the outer ring surface of the circular ring 504 gradually decreases from the middle to both sides, so that the removed sand is guided away from the sand prevention cylinder 2, thereby assisting in removing the sand outside the sand prevention cylinder 2.

[0031] As Figure 2 , Figure 3 , Figure 5 and Figure 6As shown, the anchor body 1 is fixed with the fixed rods 601 which are symmetrically distributed and respectively located in the corresponding sealing cavities 15, the sliding rods 502 are slidingly connected with the adjacent fixed rods 601, the first springs 602 are fixed between the sliding rods 502 and the anchor body 1 and sleeved outside the adjacent fixed rods 601, the two sliding rods 502 are commonly fixed with the fixed ring 701 which is located above the sand prevention cylinder 2, the tension spring 702 is fixed between the fixed ring 701 and the sand prevention cylinder 2, the sand prevention cylinder 2 is slidingly connected with the anchor body 1, the lower part of the anchor body 1 is provided with the two through holes which are symmetrically distributed, the upper side of the sand prevention cylinder 2 is provided with the shoulder part 21, the through holes of the anchor body 1 are slidingly connected with the limiting rods 801 which are used for limiting the shoulder part 21, in the initial state, the two limiting rods 801 commonly limit the shoulder part 21, the sand prevention cylinder 2 cannot move upward, the through holes of the anchor body 1 are slidingly connected with the limiting members 802 away from the shoulder part 21, the second springs 803 are fixed between the limiting members 802 and the adjacent limiting rods 801 and located in the adjacent through holes of the anchor body 1, the sliding rods 502 are provided with the guide grooves 51, the limiting members 802 are provided with the limiting parts which are rectangular, the limiting parts of the limiting members 802 slide in the adjacent guide grooves 51, the guide grooves 51 are composed of the vertical grooves and the inclined grooves, the vertical grooves of the guide grooves 51 are located above the inclined grooves, in the initial state, the limiting parts of the limiting members 802 are located above the vertical grooves of the adjacent guide grooves 51, the distance between the inclined grooves of the two guide grooves 51 gradually increases from top to bottom, the side of the limiting rods 801 close to the fixed ring 701 is provided with the inclined surface, the shoulder part 21 is used for pressing the inclined surface of the limiting rods 801, the elastic coefficient of the first springs 602 is greater than that of the second springs 803, in the process that the shoulder part 21 moves downward from the limiting rods 801 and contacts the inclined surface of the limiting rods 801, the lower side of the shoulder part 21 presses the inclined surfaces of the two limiting rods 801 so that the two limiting rods 801 move away from each other, the two second springs 803 are compressed.

[0032] Before the oil is pumped out, the state is as follows Figure 2 and Figure 3As shown, during the upstroke, the pressure in the anchor body 1 decreases, causing the pressure in the sealed cavity 15 to decrease, the two sealing plugs 501 drive the two sliding rods 502 to move upward, the upward movement of the sealing plugs 501 causes the oil in the well to slowly flow upward through the sliding connection between the sliding rods 502 and the anchor body 1 into the lower part of the sealed cavity 15, thus the sealing plugs 501 slowly move upward under the suction of the negative pressure in the anchor body 1, the two sliding rods 502 drive the two circular rings 504 to move upward through the two connecting plates 503, the sand on the outside of the sand prevention cylinder 2 is scraped off by the circular rings 504, the upward movement of the sliding rods 502 causes the adjacent first springs 602 to be compressed, during the upward movement of the two sliding rods 502, the two sliding rods 502 drive the fixed ring 701 to move upward, because the two limiting rods 801 limit the shoulder part 21, thus the sand prevention cylinder 2 cannot move upward, the tension spring 702 is stretched, and the limiting part of the limiting member 802 is located in the vertical groove of the guide groove 51, if most of the sand prevention holes of the sand prevention cylinder 2 are not blocked (the anchor body 1 is in a low negative pressure state), the oil normally enters the sand prevention cylinder 2 through the unblocked sand prevention holes, and the negative pressure in the anchor body 1 does not cause the two sealing plugs 501 to reach the position as shown. Figure 6

[0033] During the downstroke, the negative pressure in the anchor body 1 gradually disappears, the downward movement of the fixed ring 701 is driven by the release of the tension of the tension spring 702, the fixed ring 701 drives the two sliding rods 502 to move downward, at the same time, the adjacent sliding rods 502 are pushed downward by the release of the elastic force of the two first springs 602, the two sliding rods 502 drive the two sealing plugs 501 to move downward, the sealing plugs 501 cause the oil below them to slowly flow into the well through the sliding connection between the adjacent sliding rods 502 and the anchor body 1, the two sealing plugs 501 slowly move downward, the circular rings 504 are driven by the two connecting plates 503 to move downward again to scrape off the sand on the outside of the sand prevention cylinder 2, when the elastic force of the tension spring 702 and the two first springs 602 returns to the initial state, the state is as shown. Figure 2 As shown, the sand in the sand prevention cylinder 2 is scraped off by the longitudinal reciprocating movement of the circular rings 504 driven by the two connecting plates 503, ensuring the flow rate of the oil, and the diameter of the outer surface of the circular rings 504 gradually decreases from the middle to both sides, so that the scraped sand is guided away from the sand prevention cylinder 2, assisting in scraping off the sand on the outside of the sand prevention cylinder 2.

[0034] ​In the upstroke process, if most of the sand control holes of the sand control cylinder 2 are blocked, the negative pressure in the anchor body 1 causes the two sealing plugs 501 to continue to move upwards at the position of the above upstroke. Taking the right sealing plug 501 as an example, when the limiting part of the limiting piece 802 enters the inclined groove from the vertical groove of the guide groove 51, the limiting piece 802 is limited to move right by the inclined groove of the guide groove 51, and the limiting piece 802 drives the limiting rod 801 to move right through the second spring 803. When the limiting part of the limiting piece 802 is located on the lower side of the inclined groove of the guide groove 51, the limiting rod 801 no longer limits the shoulder part 21, and the state is as shown in Figure 6 The tension of the tension spring 702 in the tension state is released to drive the sand control cylinder 2 to move upwards, the oil in the anchor body 1 is discharged in reverse through the sand control holes of the sand control cylinder 2, and the sand blocked in the sand control holes of the sand control cylinder 2 is flushed out in reverse, so that the sand control holes of the sand control cylinder 2 are not blocked. In the process of moving upwards of the sand control cylinder 2, the slide rod 502 almost remains in a static state because the oil is difficult to pass through the sliding connection between the slide rod 502 and the anchor body 1 in a short time, and the fixed ring 701 remains in a static state so that the tension spring 702 can drive the sand control cylinder 2 to move upwards. When the tension of the tension spring 702 returns to the initial state, the sand control cylinder 2 no longer moves upwards, and the pressure in the anchor body 1 returns to a low negative pressure state again.

[0035] After the upstroke is completed, the elastic force of the first spring 602 in the force storage state is released, the two slide rods 502 are driven to move downwards by the two first springs 602, the fixed ring 701, the tension spring 702 and the sand control cylinder 2 are driven to move downwards by the two slide rods 502. Taking the right slide rod 502 as an example, the inclined groove of the guide groove 51 drives the limiting piece 802 to move left, and the limiting piece 802 drives the limiting rod 801 to move left through the second spring 803. The inclined surface of the limiting rod 801 is located on the path of the downward movement of the shoulder part 21, and when the limiting part of the limiting piece 802 enters the vertical groove from the inclined groove of the guide groove 51, the limiting piece 802 and the limiting rod 801 no longer move left. When the lower side of the shoulder part 21 contacts the inclined surface of the limiting rod 801, because the elastic coefficient of the first spring 602 is greater than that of the second spring 803, the shoulder part 21 drives the limiting rod 801 to move right by extruding the inclined surface of the limiting rod 801, and the second spring 803 is compressed. When the shoulder part 21 is lower than the limiting rod 801, the elastic force of the second spring 803 in the compressed state is released to drive the limiting rod 801 to move left. When the elastic force of the second spring 803 returns, the limiting rod 801 limits the shoulder part 21, the elastic force of the first spring 602 returns, and when most of the sand control holes of the sand control cylinder 2 are blocked again, the above steps are repeated. When the sand control holes of the sand control cylinder 2 are blocked, the sand control cylinder 2 is driven to move upwards by releasing the elastic force of the tension spring 702, so that the oil in the sand control cylinder 2 performs a reverse flushing operation on the sand control holes thereon, ensures that the subsequent oil smoothly passes through the sand control holes of the sand control cylinder 2, and enables the oil pumping process to proceed smoothly.

[0036] Those skilled in the art should understand that the above-mentioned embodiments do not limit the present application in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the present application.

Claims

1. A variable-pitch helical gas anchor, comprising an anchor body (1), a sand prevention cylinder (2) is installed on the lower side of the anchor body (1), the sand prevention cylinder (2) is provided with sand prevention holes, a helical blade (3) is fixedly connected in the anchor body (1), a central pipe (4) is fixedly connected to the middle of the helical blade (3), the anchor body (1), the helical blade (3) and the central pipe (4) cooperate to form a helical channel (11), a separation cavity (111) is arranged on the upper side of the helical blade (3) in the anchor body (1), the anchor body (1) is provided with an oil discharge port (12) communicating with the separation cavity (111), the anchor body (1) is provided with an oil discharge channel (13) communicating with the oil discharge port (12), the anchor body (1) is provided with an exhaust channel (14) communicating with the central pipe (4), the central pipe (4) is provided with an exhaust groove (41) communicating with the separation cavity (111), and the anchor body (1) is provided with an inverted-horn-shaped flow guide surface near the position of the exhaust groove (41). The pitch of the lower side of the spiral blade (3) is smaller than that of the upper side, the upper pitch of the spiral blade (3) gradually increases from bottom to top, and the central tube (4) is provided with exhaust holes (42) distributed in a spiral shape; the anchor body (1) is provided with symmetrically distributed sealing cavities (15), a sealing plug (501) is slidably connected in the sealing cavity (15), the sealing plug (501) is fixedly connected with a sliding rod (502) which is slidably connected with the anchor body (1), the sliding rod (502) is fixedly connected with a connecting plate (503), and the symmetrically distributed connecting plates (503) are jointly fixedly connected with a circular ring (504) which is slidably connected with the sand prevention cylinder (2); the anchor body (1) is fixedly connected with fixed rods (601) which are symmetrically distributed and located in the corresponding sealing cavities (15), the sliding rod (502) is slidably connected with the adjacent fixed rod (601), and a first spring (602) is fixedly connected between the sliding rod (502) and the anchor body (1) and sleeved on the outer side of the adjacent fixed rod (601); the symmetrically distributed sliding rods (502) are jointly fixedly connected with a fixed ring (701), a tension spring (702) is fixedly connected between the fixed ring (701) and the sand prevention cylinder (2), and the sand prevention cylinder (2) is slidably connected with the anchor body (1).

2. A pitch varying helical air anchor according to claim 1, wherein: The hole diameter of the exhaust holes (42) distributed in a spiral shape gradually increases from bottom to top.

3. A pitch varying helical air anchor according to claim 1, wherein: The diameter of the outer ring surface of the circular ring (504) gradually decreases from the middle to both sides.

4. A pitch varying helical air anchor according to claim 1, wherein: The lower part of the anchor body (1) is provided with symmetrically distributed through holes, one side of the sand prevention cylinder (2) close to the fixed ring (701) is provided with a shoulder part (21), a limiting rod (801) for limiting the shoulder part (21) is slidably connected in the through hole of the anchor body (1), a limiting piece (802) is slidably connected in the through hole of the anchor body (1) away from the shoulder part (21), and a second spring (803) is fixedly connected between the limiting piece (802) and the adjacent limiting rod (801).

5. A pitch varying helical air anchor according to claim 4, wherein: The sliding rod (502) is provided with a guide groove (51), the limiting piece (802) is provided with a limiting part in the shape of a rectangle, and the limiting part of the limiting piece (802) slides in the adjacent guide groove (51).

6. A pitch varying helical air anchor according to claim 4, wherein: One side of the limiting rod (801) close to the fixed ring (701) is provided with an inclined surface, the shoulder part (21) is used for pressing the inclined surface of the limiting rod (801), and the elastic coefficient of the first spring (602) is greater than that of the second spring (803).

7. A pitch varying helical air anchor according to claim 5 wherein: The guide groove (51) is composed of a vertical groove and an inclined groove, the vertical groove of the guide groove (51) is located above the inclined groove, and the distance between the symmetrically distributed inclined grooves gradually increases from top to bottom.

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