Composite cavity type well completion sand filtering pipe

Abstract

The invention relates to the technical field of sand control screen pipes, in particular to a composite cavity type well completion sand filter pipe. Comprising a sieve tube, uniformly distributed filter holes are formed in the sieve tube, a confluence cavity communicated with all the filter holes is formed in the sieve tube, lower connecting pieces which are annularly and uniformly distributed and upper connecting pieces which are annularly and uniformly distributed are arranged on the outer side of the sieve tube, and the lower connecting pieces and the upper connecting pieces are in one-to-one correspondence; the lower connecting pieces and the corresponding upper connecting pieces are jointly and fixedly connected with extrusion strips, and the screen pipe, all the lower connecting pieces, all the upper connecting pieces and all the extrusion strips jointly form a primary filtering cavity. The sand layer is formed by intercepting gravels through the screen pipe, the sand layer on the peripheral side of the screen pipe is extruded through the extrusion strips, the shape of the sand layer is kept stable, in this way, sand prevention is conducted through the sand layer, the step of additionally filling the gravels is omitted, the installation process is simplified, the time needed for installation is shortened, and then the installation efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sand control screen pipe, and particularly to a composite cavity type well completion sand filter pipe. BACKGROUND

[0002] The well completion sand filter pipe, commonly known as sand control screen pipe or oil well sand filter, is a key downhole tool installed at the reservoir position at the bottom of the oil well in oil and gas exploitation, which allows crude oil to flow into the wellbore through physical filtration while effectively blocking sand; the traditional screen pipe relies on the screen to directly intercept sand, but under the impact of high-speed sand-containing fluid, the kinetic energy of the sand particles is large, and they continuously impact the surface of the screen, causing material wear and eventually causing erosion damage. To solve this problem, gravel packing completion is often used in the field: after the screen pipe is lowered into the well, gravel is filled into the annulus between the screen pipe and the wellbore to form an outer sand layer. This sand layer acts as a pre-filter barrier, intercepting large particles of sand in the fluid and significantly reducing fluid flow rate and kinetic energy, thereby reducing the direct erosion of the screen by sand-containing fluid. However, this filling operation is cumbersome, resulting in a long installation time for the screen pipe and affecting operational efficiency. SUMMARY

[0003] The present application provides a composite cavity type well completion sand filter pipe to overcome the shortcomings of long installation time and low operational efficiency of existing sand filter pipes.

[0004] The technical implementation of the present application is as follows: a composite cavity type well completion sand filter pipe, comprising: a screen pipe, the screen pipe is provided with uniformly distributed filter holes, a flow collection cavity is arranged in the screen pipe and communicates with all the filter holes, an annular uniformly distributed lower tab and an annular uniformly distributed upper tab are arranged on the outer side of the screen pipe, the lower tab corresponds to the upper tab one by one, the lower tab and the upper tab can swing relative to the screen pipe, the lower tab and the corresponding upper tab are jointly fixed with an extrusion strip, the screen pipe, all the lower tabs, all the upper tabs and all the extrusion strips jointly constitute a primary filter cavity, the primary filter cavity is used to accommodate sand to form a sand layer for sand control, a power assembly is arranged in the screen pipe for controlling the movement of all the extrusion strips to change the volume of the primary filter cavity.

[0005] Further, the power assembly comprises: a connecting ring connected slidingly in the screen pipe, one end of the upper tab close to the extrusion strip is fixedly connected with a traction rope, the screen pipe is provided with a communication hole close to all the traction ropes, the traction rope is fixedly connected with the connecting ring after passing through adjacent communication holes, the connecting ring is provided with annularly distributed shielding flaps, the shielding flaps are used to shield the middle part of the connecting ring, and the fluid drag force of the shielding flaps is used to provide power for the movement of the connecting ring when crude oil flows in the flow collection cavity.

[0006] Further, the through hole is provided with annular arc surfaces at both ends, which are used to reduce the friction when the traction rope slides in the through hole.

[0007] Further, the connecting ring is fixed with hinge rods equal in number to the shutter panels, the hinge rods are rotationally connected with the shutter panels, elastic sheets are fixed on the connecting ring near all the shutter panels, one end of each elastic sheet away from the connecting ring is fixed with a corresponding shutter panel, the shutter panel is provided with a sliding groove, a sliding block is limitedly and slidingly connected in the sliding groove, a fixing bolt is threadedly connected with the sliding block, and a pressing plate is rotationally connected with the fixing bolt.

[0008] Further, the shutter panel is provided with a hinge part near the adjacent hinge rod, the hinge part is cylindrical, the hinge rod is not coaxial with the adjacent hinge part, and the hinge part is used to press the adjacent elastic sheet when the adjacent shutter panel rotates.

[0009] Further, the connecting ring is fixed with connecting blocks at positions corresponding to all the shutter panels, and the connecting blocks are threadedly connected with adjusting bolts, which are used to press the adjacent shutter panel.

[0010] Further, the lower connecting piece and the upper connecting piece are both made of elastic material and always have a tendency to drive the adjacent extrusion strip away from the screen pipe.

[0011] Further, the screen pipe is fixed with a dissolving column, and the dissolving column is fixed with the connecting ring.

[0012] Further, the extrusion strip is provided with a plurality of grooves on the side away from the screen pipe, and the grooves are used to enhance the bending strength of the extrusion strip.

[0013] Further, the extrusion strip is provided with an arc-shaped strip surface on the side near the screen pipe, and the arc-shaped strip surface is used to assist the gravel in the primary filtering cavity to gather.

[0014] Overall, compared with the prior art, the above technical solutions of the present application can achieve the following beneficial effects: the present application forms a sand layer by intercepting the gravel by the screen pipe, and keeps the sand layer stable by extruding the sand layer outside the screen pipe by the extrusion strip, so that the sand layer is used for sand prevention, the step of filling sandstone is eliminated, the installation process is simplified, the installation time is shortened, and the installation efficiency is improved.

[0015] The length of the free part of the elastic sheet is limited by the pressing plate, so as to adjust the length of the bending part of the elastic sheet driven by the shielding fan plate during swinging, change the elastic force required to be overcome by the elastic sheet during deformation, change the threshold value of the shielding fan plate relative to the connecting ring during swinging, and then change the maximum extrusion force of the extrusion strip on the sand layer, so as to reduce the probability of damage to the sand layer structure caused by the extrusion strip.

[0016] By stopping oil production, the connecting ring and the shielding fan plate are no longer affected by the fluid drag force, the extrusion strip is away from the screen pipe under the elastic force of the lower connecting piece and the upper connecting piece, and the extrusion on the sand layer is released, so that the original sand layer is self-dispersed under the action of gravity; after resuming oil production, the sand gravel is adsorbed again to form a new sand layer, so that the sand layer is conveniently replaced, the oil production efficiency is improved, and the casing, well wall and the like are not affected. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a schematic diagram of the three-dimensional structure of the present application; Figure 2 It is a schematic diagram of the three-dimensional structure of the screen pipe and the extrusion strip of the present application; Figure 3 It is a schematic diagram of the three-dimensional structure of the lower connecting piece and the upper connecting piece of the present application; Figure 4 It is a schematic diagram of the three-dimensional structure of the upper connecting piece and the connecting ring of the present application; Figure 5 It is a schematic diagram of the three-dimensional structure of the shielding fan plate and the dissolving column of the present application; Figure 6 It is a schematic diagram of the three-dimensional structure of the connecting ring and the shielding fan plate of the present application; Figure 7 It is a schematic diagram of the three-dimensional structure of the lower connecting piece and the extrusion strip of the present application.

[0018] The meanings of the reference signs in the drawings are as follows: 1-screen pipe, 101-filter hole, 102-converging cavity, 2-lower connecting piece, 3-upper connecting piece, 4-extrusion strip, 401-primary filter cavity, 402-groove, 403-arc-shaped strip surface, 5-pulling rope, 501-communication hole, 502-annular arc surface, 6-connecting ring, 7-shielding fan plate, 701-hinge part, 8-connecting block, 9-adjusting bolt, 10-hinge rod, 11-elastic sheet, 12-sliding block, 121-sliding groove, 13-fixing bolt, 14-pressing plate, 15-dissolving column. DETAILED DESCRIPTION

[0019] In order to make the technical means, creative features, purposes and effects achieved by the present application easy to understand, the present application will be further described below in combination with specific embodiments. Example 1

[0020] The embodiment provides a composite cavity type well completion sand filter pipe, which solves the problems of long installation time and low operation efficiency of the existing sand filter pipe.

[0021] Referring to Figures 1 to 4 , the composite cavity type well completion sand filter pipe comprises a screen pipe 1, the screen pipe 1 is provided with uniformly distributed filter holes 101, the filter holes 101 are used for intercepting sand and allowing crude oil to pass through the screen pipe 1, the screen pipe 1 is provided with a flow collection cavity 102 in communication with all the filter holes 101, the outer side of the screen pipe 1 is provided with annular uniformly distributed lower lugs 2 and annular uniformly distributed upper lugs 3, in the axial direction of the screen pipe 1, the lower lugs 2 correspond to the upper lugs 3 one by one, the lower lugs 2 and the upper lugs 3 can swing relative to the screen pipe 1, the lower lugs 2 and the corresponding upper lugs 3 are jointly fixed with extrusion strips 4, the screen pipe 1, all the lower lugs 2, all the upper lugs 3 and all the extrusion strips 4 jointly form a primary filtration cavity 401, the primary filtration cavity 401 is used for containing sand to form a sand layer for sand control, and the screen pipe 1 is provided with a power assembly used for controlling movement of all the extrusion strips 4 to change the volume of the primary filtration cavity 401.

[0022] The above arrangement can realize that the sand layer is formed by the interception of the screen pipe 1 on the sand, and the extrusion strips 4 extrude the sand layer on the outer circumferential side of the screen pipe 1, so that the sand layer form is kept stable, sand control is performed by using the sand layer, the step of additional filling of sand is omitted, the installation process is simplified, the installation time is shortened, and the installation efficiency is improved.

[0023] It should be noted that, in the embodiment, the setting relationship of the lower lugs 2 and the upper lugs 3 with the screen pipe 1 can be regarded as rotary connection.

[0024] Referring to Figure 4 and Figure 5 , the power assembly comprises a connecting ring 6 which is slidingly connected in the screen pipe 1, a clamp (see Figure 4 ) is arranged in the screen pipe 1, and the clamp is used for limiting the lower limit position of the connecting ring 6; one end of the upper lug 3 close to the extrusion strip 4 is fixedly connected with a traction rope 5, the screen pipe 1 is provided with a through hole 501 close to all the traction ropes 5, the upper end of the traction rope 5 is fixedly connected with the connecting ring 6 after passing through the adjacent through hole 501, the connecting ring 6 is provided with three annular distributed shielding flaps 7, the shielding flaps 7 are used for shielding the middle part of the connecting ring 6, there is a gap between the shielding flaps 7 and the connecting ring 6, so as to reduce the flow area when fluid flows upward along the flow collection cavity 102, the fluid drag of the shielding flaps 7 by the crude oil flowing in the flow collection cavity 102 provides power for the movement of the connecting ring 6, and then the traction rope 5 pulls the extrusion strip 4 to swing, so that the extrusion strip 4 extrudes the sand layer.

[0025] The number and area of the shielding fan plates 7 are determined according to the optimum oil production rate (corresponding to the maximum flow rate of the fluid) of the oil well to be installed and the viscosity of the fluid, in the case of the optimum oil production rate, the fluid drag force provides an upward force on the shielding fan plates 7 sufficient to drive the connection ring 6, the traction rope 5 and the extrusion strip 4 to move together, but in the case of less than the optimum oil production rate, the fluid drag force provides an upward force on the shielding fan plates 7 insufficient to overcome the gravity of the connection ring 6, that is, the connection ring 6 cannot be moved.

[0026] It should be noted that in the present embodiment, the shielding fan plates 7 and the connection ring 6 can be considered as fixedly connected, and in the present embodiment, the lower tabs 2, the upper tabs 3 and the extrusion strips 4 are attached to the filter screen 1 at the initial time, and the connection ring 6 is in contact with the lower clamps at the initial time. Figure 3

[0027] Workflow: After the casing is lowered into the oil well, the device is installed to the designated position of the casing by using the tool, and then the oil production is started, and the oil production rate is controlled to be lower than the optimum oil production rate. During the oil production process, due to the pressure difference between the inside and outside of the casing, the fluid in the formation will continuously flow into the casing. Specifically: the sand-containing fluid in the formation enters the primary filtration cavity 401 through the gap between the adjacent two extrusion strips 4, and then the sand-containing fluid enters the converging cavity 102 after passing through the filter holes 101, and starts to flow upward along the converging cavity 102. In the process of the sand-containing fluid passing through the filter holes 101, the filter holes 101 intercept the sand and gravel larger than the pore size of the filter holes 101 in the sand-containing fluid, and the intercepted sand and gravel are stably attached to the outer circumferential side of the screen pipe 1 under the action of fluid drag force, gravity and the bite force between the sand and gravel, that is, they are kept in the primary filtration cavity 401; and since the filter holes 101 are uniformly distributed on the outer circumferential side of the screen pipe 1, the sand and gravel will be uniformly deposited and accumulated in the primary filtration cavity 401, and finally form a continuous annular sand layer wrapped around the outer circumferential side of the screen pipe 1; and the sand-containing fluid flows upward in the converging cavity 102, and continues to flow upward after passing through the gap between the connection ring 6 and the three shielding fan plates 7, in this process, the connection ring 6 remains in a stationary state.

[0028] ​After the specified duration (the duration is determined according to the sand content in the sand-containing fluid, and is intended to wait for the sand layer on the peripheral side of the screen pipe 1 to reach the ideal thickness after the specified duration), the oil production rate is increased to the optimal oil production rate, so that the fluid drag on the blocking fan plate 7 increases when the fluid flows in the confluence cavity 102, the connecting ring 6 is driven upward by the blocking fan plate 7, the connecting ring 6 drives all the upper tabs 3 to swing upward together through all the traction ropes 5, the upper tabs 3 drive the adjacent compression strips 4 and the adjacent lower tabs 2 to move, since the screen pipe 1, the lower tabs 2, the upper tabs 3 and the compression strips 4 form a parallelogram structure, so in the process of swinging of the upper tabs 3, the compression strips 4 will move closer to the screen pipe 1, so that the volume of the primary filter cavity 401 is reduced, and the sand layer formed in the primary filter cavity 401 is compressed by the compression strips 4, so that the state of the sand layer is stable; in this way, a stable sand layer can be formed without additional filling of sand, and the sand-containing fluid is pre-filtered by using the sand layer to reduce the kinetic energy of the sand-containing fluid and reduce the direct erosion of the sand-containing fluid on the screen pipe 1. Example 2

[0029] This embodiment is further optimized on the basis of example 1.

[0030] Referring to Figure 4 Both ends of the communication hole 501 are provided with annular arc surfaces 502, which are used to reduce the friction when the traction rope 5 slides in the communication hole 501. Example 3

[0031] This embodiment is further optimized on the basis of example 2 to limit the maximum compression force of the compression strips 4 on the sand layer.

[0032] Referring to Figure 5 and Figure 6The connecting ring 6 is fixedly connected with a number of hinged rods 10 equal to that of the shielding fan plates 7, the hinged rods 10 are rotationally connected with the shielding fan plates 7, so that the shielding fan plates 7 can swing relative to the connecting ring 6; the connecting ring 6 is fixedly connected with elastic sheets 11 near all the shielding fan plates 7, the elastic sheets 11 are made of high-temperature-resistant elastic metal material, one end of the elastic sheet 11 away from the connecting ring 6 is fixedly connected with the corresponding shielding fan plate 7, so that the force required for the deformation of the three elastic sheets 11 is greater than the gravity of the connecting ring 6, that is, the fluid drag will first drive the connecting ring 6 to move before driving the elastic sheet 11 to deform; the shielding fan plate 7 is provided with two symmetrically distributed sliding grooves 121, the sliding grooves 121 are limitedly and slidably connected with sliding blocks 12, the sliding blocks 12 are threadedly connected with fixed bolts 13, the two fixed bolts 13 on the same shielding fan plate 7 are rotationally connected with a pressing plate 14, and the pressing plate 14 is used for pressing the corresponding elastic sheet 11 (hereinafter, the part of the elastic sheet 11 between the pressing plate 14 and the connecting ring 6 is referred to as a free part, and the free part will deform when the shielding fan plate 7 swings; the part of the elastic sheet 11 on the side of the pressing plate 14 close to the axis of the connecting ring 6 is attached to the adjacent shielding fan plate 7, and this part will not deform when the shielding fan plate 7 swings).

[0033] The above arrangement can achieve that the length of the free part of the elastic sheet 11 is limited by the pressing plate 14, so as to adjust the length of the bending part of the elastic sheet 11 driven by the shielding fan plate 7 during swinging, change the elastic force required to be overcome by the elastic sheet 11 during deformation, change the threshold value of the swinging of the shielding fan plate 7 relative to the connecting ring 6, and further change the maximum extrusion force of the extrusion strip 4 on the sand layer, thereby reducing the probability of damage to the sand layer structure caused by the extrusion strip 4.

[0034] During the oil extraction operation at the optimal oil extraction rate, after the fluid drives the shielding fan plate 7 and the connecting ring 6 to move upward through fluid drag, the extrusion strip 4 and the connecting ring 6 stop moving after the extrusion strip 4 contacts the sand layer, in this state, the fluid drag directly changes into the extrusion force of the extrusion strip 4 on the sand layer, in order to prevent the extrusion force of the extrusion strip 4 on the sand layer from being too large to cause the sand layer to be tightly combined or the gravel to be crushed and extruded, the following measures are taken: after the connecting ring 6 stops moving, the shielding fan plate 7 swings under the action of the fluid drag, the shielding fan plate 7 drives the adjacent elastic sheet 11 to bend, and after the shielding fan plate 7 swings, the gap between the shielding fan plate 7 and the connecting ring 6 and the gap between the adjacent two shielding fan plates 7 are increased, the fluid drag acting on the shielding fan plate 7 is reduced, so as to reduce the extrusion force of the extrusion strip 4 on the sand layer, thereby reducing the probability of damage to the sand layer.

[0035] Referring to Figure 5, the position of the shielding fan plate 7 close to the adjacent hinged rod 10 is provided with a hinge part 701, the hinge part 701 is cylindrical, and the hinged rod 10 is not coaxial with the adjacent hinge part 701, initially, the side of the hinge part 701 away from the axis of the connecting ring 6 has the smallest distance with the hinged rod 10, during the swinging of the shielding fan plate 7, the hinge part 701 rotates around the hinged rod 10, so that the distance between the side of the hinge part 701 away from the axis of the connecting ring 6 and the hinged rod 10 gradually increases, the hinge part 701 extrudes the adjacent elastic sheet 11, so that the extrusion force between the elastic sheet 11 and the screen pipe 1 increases, and then the friction between the elastic sheet 11 and the screen pipe 1 increases, and the friction is used to keep the relative position of the connecting ring 6 and the screen pipe 1 stable. Embodiment 4

[0036] This embodiment is further optimized on the basis of embodiment 3 to improve the convenience of adjusting the flow area of the middle part of the connecting ring 6.

[0037] Referring to Figure 5 and Figure 6 , the positions corresponding to all shielding fan plates 7 in the connecting ring 6 are fixedly connected with connecting blocks 8, the connecting blocks 8 are threadedly connected with adjusting bolts 9, and the adjusting bolts 9 are used to extrude adjacent shielding fan plates 7.

[0038] The above arrangement can realize that the initial position of the shielding fan plate 7 is changed by extruding the shielding fan plate 7 through the adjusting bolt 9, the projection area of the shielding fan plate 7 on the horizontal plane is changed, the flow area between the shielding fan plate 7 and the connecting ring 6 at the initial time is adjusted, and then the oil well with different oil production rates is adapted. Embodiment 5

[0039] This embodiment is further optimized on the basis of embodiment 4.

[0040] After the sand layer is used for a long time, the content of fine sand accumulated in the sand layer increases, the porosity of the sand layer decreases, the sand layer is blocked, and the flow rate of the formation fluid to the casing is affected; when the problem occurs, the fine sand blocked in the sand layer is usually treated by physical flushing to be back-flushed and discharged, but the method takes a long time, and the original sand layer structure is easily damaged, and the screen pipe, the well wall and the casing are easily eroded and worn.

[0041] Referring to Figure 3 , the lower connecting piece 2 and the upper connecting piece 3 are both of elastic material, and both always have a tendency to drive the adjacent extrusion strip 4 away from the screen pipe 1, that is, when the extrusion strip 4 is in the attached Figure 3 As shown in the state, the lower connecting piece 2 and the upper connecting piece 3 still have a tendency to drive the extrusion strip 4 to move outward.

[0042] It should be noted that in the present embodiment and subsequent embodiments, the fluid drag needs to overcome the sum of the gravity of the connecting ring 6 and the elastic force of the lower and upper tabs 2 and 3 when driving the connecting ring 6 and the shielding fan plate 7 to move.

[0043] The above arrangement can achieve that, by the elasticity of the lower and upper tabs 2 and 3, after the sand layer is used for a long time, the connecting ring 6 and the shielding fan plate 7 are no longer affected by the fluid drag by stopping oil production, the extrusion strip 4 is away from the screen pipe 1 under the elastic force of the lower and upper tabs 2 and 3 and releases the extrusion on the sand layer, so that the original sand layer collapses under the action of gravity; after resuming oil production, the sand and gravel are adsorbed again to form a new sand layer, so that the sand layer is conveniently replaced, the oil production efficiency is improved, and the casing, well wall and the like are not affected. Embodiment 6

[0044] The present embodiment is further optimized on the basis of Embodiment 5.

[0045] Referring to Figure 4 and Figure 5 , the screen pipe 1 is fixedly connected with a dissolving column 15, the dissolving column 15 is made of a soluble material (such as a soluble magnesium alloy or a polymer material) and can be slowly dissolved in the fluid downhole; the dissolving column 15 is fixedly connected with the connecting ring 6.

[0046] The above arrangement can achieve that, by the limiting of the dissolving column 15 on the connecting ring 6, the extrusion strip 4 can keep close to the screen pipe 1 during installation of the device, thereby reducing the outer diameter of the device and facilitating installation; after the device is installed, the dissolving column 15 gradually dissolves and finally releases the limiting on the connecting ring 6, so that the connecting ring 6 moves downward and contacts the clamp under the elastic force of the lower and upper tabs 2 and 3 and the gravity of the connecting ring 6. Embodiment 7

[0047] The present embodiment is further optimized on the basis of Embodiment 6.

[0048] Referring to Figure 7 , the side of the extrusion strip 4 away from the screen pipe 1 is provided with a plurality of grooves 402 for enhancing the bending strength of the extrusion strip 4; the side of the extrusion strip 4 close to the screen pipe 1 is provided with an arc-shaped strip surface 403 for assisting the sand gravel in the primary filter cavity 401 to gather.

[0049] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application.

Claims

1. A composite cavity type completion sand screen pipe, comprising: a screen pipe (1) provided with uniformly distributed filter holes (101) and a flow collection cavity (102) in communication with all the filter holes (101), characterized in that the outer side of the screen pipe (1) is provided with annular uniformly distributed lower tabs (2) and annular uniformly distributed upper tabs (3), the lower tabs (2) correspond to the upper tabs (3) one by one, the lower tabs (2) and the upper tabs (3) can swing relative to the screen pipe (1), the lower tabs (2) and the corresponding upper tabs (3) are jointly fixed with extrusion strips (4), the screen pipe (1), all the lower tabs (2), all the upper tabs (3) and all the extrusion strips (4) jointly form a primary filtration cavity (401) for containing sand to form a sand layer for sand control, and the screen pipe (1) is provided with a power assembly for controlling the movement of all the extrusion strips (4) to change the volume of the primary filtration cavity (401).

2. A composite cavity completion screen as defined in claim 1, wherein: The power assembly comprises: a connecting ring (6) slidingly connected in the screen pipe (1), one end of the upper tab (3) near the extrusion strip (4) is fixedly connected with a traction rope (5), the screen pipe (1) is provided with a communication hole (501) near the position of all the traction ropes (5), the traction rope (5) is fixedly connected with the connecting ring (6) after passing through the adjacent communication holes (501), the connecting ring (6) is provided with annular distributed shielding flaps (7), the shielding flaps (7) are used for shielding the middle part of the connecting ring (6), and the fluid drag force of the shielding flaps (7) when crude oil flows in the flow collection cavity (102) provides power for the movement of the connecting ring (6).

3. A composite cavity completion screen as defined in claim 2, wherein: Both ends of the communication hole (501) are provided with annular arc surfaces (502) for reducing the friction when the traction rope (5) slides in the communication hole (501).

4. A composite cavity completion screen as defined in claim 2, wherein: The connecting ring (6) is fixedly connected with hinge rods (10) equal in number to the shielding flaps (7), the hinge rods (10) are rotationally connected with the shielding flaps (7), the connecting ring (6) is fixedly connected with elastic sheets (11) near all the shielding flaps (7), one end of the elastic sheet (11) away from the connecting ring (6) is fixedly connected with the corresponding shielding flap (7), the shielding flap (7) is provided with a sliding groove (121), a sliding block (12) is slidingly connected in the sliding groove (121), the sliding block (12) is threadedly connected with a fixing bolt (13), the fixing bolt (13) is rotationally connected with a pressing plate (14), and the pressing plate (14) is used for extruding the corresponding elastic sheet (11).

5. A composite cavity completion screen as defined in claim 4, wherein: The blocking fan plate (7) is provided with a hinge part (701) near the position of the adjacent hinge rod (10), the hinge part (701) is cylindrical, and the hinge rod (10) is not coaxial with the adjacent hinge part (701), the hinge part (701) is used for extruding the adjacent elastic sheet (11) when the adjacent blocking fan plate (7) rotates.

6. A composite cavity completion screen as defined in claim 5, wherein: The connecting ring (6) is provided with a connecting block (8) corresponding to all the blocking fan plates (7), the connecting block (8) is threadedly connected with an adjusting bolt (9), and the adjusting bolt (9) is used for extruding the adjacent blocking fan plate (7).

7. A composite cavity completion screen as defined in claim 2 wherein: The lower connecting piece (2) and the upper connecting piece (3) are both of elastic material, and both always have a trend of driving the adjacent extruding strip (4) away from the screen pipe (1).

8. A composite cavity completion screen according to claim 6, wherein: The screen pipe (1) is fixedly connected with a dissolving column (15), and the dissolving column (15) is fixedly connected with the connecting ring (6).

9. A composite cavity completion screen according to claim 8, characterised in that: The extruding strip (4) is provided with a plurality of grooves (402) on the side away from the screen pipe (1), and the grooves (402) are used for enhancing the bending strength of the extruding strip (4).

10. A composite cavity completion screen according to claim 9, wherein: The extruding strip (4) is provided with an arc-shaped strip surface (403) on the side close to the screen pipe (1), and the arc-shaped strip surface (403) is used for assisting the gravel in the primary filtering cavity (401) to gather.

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