CN114320195B - A reversing joint for continuous sand flushing and well flushing - Google Patents

Abstract

The invention provides a reversing joint for continuous sand flushing and well flushing, which comprises an outer shell and a reversing assembly, wherein the reversing assembly is arranged in the outer shell; the outer shell comprises an upper connector, an outer cylinder and a lower connector which are sequentially connected from top to bottom; the reversing assembly comprises a sealing seat, a valve core and a plurality of sealing rings; the sealing seat is arranged in the upper joint, the lower end of the valve core is provided with a spring, the spring is arranged between the valve core and the outer cylinder, and the lower end of the spring is connected with the upper end face of the lower joint; the outer cylinder is provided with a through hole serving as an outer through hole; a through hole is arranged on the side surface of the lower section of the valve core and is used as an inner through hole, and the diameter of the inner through hole is the same as that of the outer through hole; the valve core moves axially in the outer cylinder to realize the switching of opening and closing of the upper joint to the valve core inner cavity flow passage and the outer through hole to the valve core inner cavity flow passage. The invention can realize continuous sand flushing operation with high efficiency and high quality without stopping the pump.

Description

A reversing joint for continuous sand flushing and well flushing

technical field

The invention belongs to the technical field of oil and gas field development, in particular to the technical field of continuous sand washing and well washing tools for oil and gas fields, in particular to a reversing joint for continuous sand washing and well washing.

Background technique

In the process of oil and gas production, the sand particles in the formation inevitably enter the wellbore along with the oil and gas production. Among them, some sand particles are carried to the ground by oil and gas, and deposited in pipelines and equipment; some sand particles are deposited at the bottom of the well, and gradually increase with the prolongation of production time, thereby blocking production layers, downhole pipe strings, etc., resulting in a decline in oil and gas production . Therefore, when the downhole sand particles accumulate to a certain thickness, well washing operations are required. Sand flushing is an important means of cleaning the sand accumulation in the wellbore of oil and gas wells. The method is to use the sand flushing fluid to carry the sand particles at the bottom of the well to the ground.

When ordinary tubing is used for sand flushing and well flushing, it is necessary to extend the sand flushing string by connecting a single piece. In order to avoid the sand settlement in the wellbore caused by the stop of the pump during the single connection process, which will affect the quality and efficiency of well washing, the reversing joint, self-sealing wellhead reversing, reversing valve, and circulation pipeline are used to realize continuous sand washing operation. The existing reversing joint has deficiencies such as the spring is easily stuck, the valve core cannot be reset, and the flow cross section is small and easy to be blocked, which leads to the failure of sand flushing and well flushing.

Therefore, the present invention provides a reversing joint for continuous sand flushing and well flushing that overcomes spring sticking and cross-section, which is of great value for realizing non-stop pumping, high efficiency, and high-quality continuous sand flushing and well flushing operations.

Contents of the invention

In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a reversing joint for continuous sand washing and well washing, which can realize non-stop pumping, high efficiency and high quality continuous sand washing and well washing operations.

The technical scheme adopted in the present invention is:

A reversing joint for continuous sand flushing, comprising an outer casing and a reversing assembly, the reversing assembly is installed inside the outer casing; the outer casing includes an upper joint, an outer cylinder, a lower Joint; the reversing assembly includes a sealing seat, a valve core, a spring, a first sealing ring, a second sealing ring, a third sealing ring, a fourth sealing ring, a fifth sealing ring, a sixth sealing ring, and a seventh sealing ring Ring, the eighth sealing ring; the sealing seat is installed inside the upper joint, the lower end of the valve core is provided with a spring, the spring is installed between the valve core and the outer cylinder, the spring is connected to the lower joint, and the lower end of the valve core The cylinder is installed in the annular groove of the lower joint; a through hole is set on the outer cylinder as the outer through hole; a through hole is set on the lower side of the valve core as the inner through hole; the diameter of the inner through hole is the same as that of the outer through hole, and the valve core Move in the axial direction inside the outer cylinder to realize the opening and closing switch from the upper joint to the flow channel in the inner cavity of the valve core, and from the outer through hole to the inner cavity of the valve core; when the inner through hole and the outer through hole are connected and coaxial, the outer through hole The flow channel from the through hole to the inner cavity of the valve core is opened, the valve core and the sealing seat are in contact with each other and sealed, and the flow channel from the upper joint to the inner cavity of the valve core is closed; The flow channel is closed, the flow channel between the valve core and the sealing seat is opened, and the flow channel from the upper joint to the inner cavity of the valve core is opened.

Preferably, the upper joint is divided into upper and lower parts, the inner lower part of the upper joint is provided with an annular step, and at least eight axial through holes are provided in the circumferential direction of the annular step, and the lower part of the upper joint is provided with an internal thread ; The outer wall of the sealing seat is provided with external threads, and an axially threaded blind hole is provided on the sealing seat; the external thread of the sealing seat is connected with the internal thread on the upper part of the upper joint, and the sealing is adjusted by rotating the sealing seat The axial relative position of the seat and the thread of the upper joint, so as to realize the adjustable opening pressure of the valve core; when the rotating sealing seat reaches the design position, the locking bolt passes through the through hole on the annular step of the upper joint and connects with the thread on the sealing seat , lock the seal seat to prevent the seal seat from rotating under the action of fluid shock and vibration.

Preferably, the outside of the lower part of the upper joint is provided with an external thread and a smooth surface from top to bottom, and the external thread is used to connect with the inner side of the outer cylinder, and a second sealing ring is provided on the contact surface between the smooth surface and the outer cylinder. There are four radial holes on the inner side of the lower part. The radial holes are opened outward from the inner side of the lower part of the upper joint near the upper end, and an axial hole extending downward and penetrating to the lower end surface of the lower part of the upper joint is provided in the wall. The spool includes upper, middle and lower sections, the upper section of the spool is used to form a line seal with the sealing seat, the outer diameter of the middle section of the spool is smaller than the lower section of the spool, the outer wall of the middle section of the spool is connected to the lower end of the upper joint The inner wall is a clearance fit, and a first sealing ring is provided between the middle outer wall of the valve core and the inner wall of the lower end of the upper joint, and a second sealing ring is provided between the outer wall of the lower end of the valve core and the outer cylinder; the sand washing pipe string is normally lowered At this time, the sand washing liquid is injected from the upper connection, and through the main through hole of the sealing seat, a vertical downward force acting on the step surface of the valve core is generated; at the same time, the sand washing liquid passes through the radial The hole and the axial hole connected with the radial hole flow into the hydraulic cylinder composed of the valve core and the outer cylinder. At the same time, the pressure of the sand washing fluid acts on the arc-shaped surface at the top of the valve core to generate a vertical downward force. , this force helps the spool to open and increases the opening of the spool.

Preferably, at least two rows of balls are arranged between the spool and the outer cylinder, the balls are embedded in the wall of the spool or the outer cylinder, and at least three balls are arranged in the circumferential direction of each row of balls, which is beneficial to improve the valve core relative to the outer cylinder. The coaxiality of the cylinder, and the valve core and the outer cylinder form a rolling pair, which reduces the frictional resistance of the axial movement of the valve core and reduces the risk of the valve core being stuck.

Preferably, two threaded blind holes are provided in the circumferential direction of the middle part of the valve core, and two L-shaped grooves are provided on the side of the outer cylinder, and the pins pass through the L-shaped grooves on the outer cylinder and are threadedly connected with the threaded holes of the valve core; The spool and the outer cylinder are respectively provided with a fourth sealing ring and a fifth sealing ring above and below the threaded hole of the pin, which are used to seal the L-shaped groove; when the spool is stuck, the pin can be applied manually. The force along the axial direction of the spool drives the spool to move in the L-shaped groove, thereby releasing the jamming; the groove surface on the upper side of the horizontal section of the L-shaped groove is provided with teeth, and the cylindrical surface of the pin is provided with a groove The teeth on the groove surface on the horizontal section of the horizontal section mesh with each other, and the teeth on the cylindrical surface of the pin mesh with the teeth on the groove to form a self-locking, so that the channel at the sealing seat of the valve core is in a normally open state, reducing the local sand washing fluid. Pressure loss, spool vibration.

Preferably, as the outer through hole, the through hole provided on the side of the lower section of the valve core has the same diameter as the outer through hole. The seventh sealing ring and the sixth sealing ring; there is an annular sinking groove at the upper end of the lower joint, and the bottom cylinder of the valve core is installed inside the annular sinking groove, and the spring is installed between the bottom cylinder of the valve core and the outer cylinder. The upper end of the spring is pressed against the stepped surface of the lower end of the spool, and the lower end of the spring is pressed against the stepped surface of the lower joint. An eighth sealing ring is arranged between the bottom cylinder of the spool and the wall of the lower joint annular sinker.

Beneficial effects of the present invention:

1. The invention creatively proposes the way that the upper joint and the spool constitute the hydraulic cylinder. Through hydraulic drive, the driving force for opening the spool and the opening of the spool are increased, and the risk of the spool being stuck and blocked is reduced; Using this method, compared with the traditional way of opening and closing by throwing a ball, can greatly improve the efficiency of use, reduce the chance of accidental freezes and other problems during the process, save costs, and reduce the time for follow-up maintenance.

2. Through the setting of the matching mode of the upper joint and the sealing seat, it is easy to adjust the installation position, and provide a changeable outflow space for the stroke of the spring, so as to realize adjustability.

3. The present invention forms a self-lock through the engagement of the pin and the teeth on the L-shaped groove, so that the valve core compresses the spring downward, so that the flow path from the upper joint, the through hole of the valve core to the inner cavity of the valve core is in a normally open state, reducing the impact. Partial pressure loss of sand fluid, avoiding valve core vibration and fluid shock induced by fluid pressure and spring force;

When the spool is stuck because it has been placed for too long or encounters debris and cannot move up and down, the pin can be operated to move the pin in the F-shaped groove, thereby driving the spool to move up and down in the outer cylinder to release the spool. stuck state.

4. There is a ball between the outer cylinder and the valve core, so that the outer cylinder and the valve core form a rolling pair, which effectively reduces the frictional resistance of the axial movement of the valve core, reduces the risk of the valve core being stuck, and improves its concentricity. degree, reducing internal wear.

Description of drawings

Fig. 1 is a schematic sectional view of the structure of the present invention;

Fig. 2 is the upper detail diagram of Fig. 1;

Figure 3 is a detailed view of the middle part of Figure 1;

Fig. 4 is the bottom detailed view of Fig. 1;

Fig. 5 is a schematic diagram of the flow of the sand washing fluid during the process of connecting the sand washing pipe string to a single piece;

Figure 6 is a schematic diagram of the flow of sand washing fluid during the normal lowering of the sand washing string;

Fig. 7 is a schematic diagram of the flow of the sand washing fluid in the process of connecting the sand washing pipe string to a single root;

Fig. 8 is a schematic diagram of the flow of the sand washing liquid in the present invention during the normal lowering of the sand washing string;

Fig. 9a-Fig. 9c are right views of the outside of the outer cylinder during the movement of the valve core driven by the pin;

Figure 10 is a schematic structural view of the upper joint;

Fig. 11 is a cross-sectional view of A-A in Fig. 10;

Figure 12 is a schematic structural view of the valve core.

In the picture:

100. Reversing joint,

1. Upper joint, 2. Seal seat, 3. Outer cylinder, 4. First sealing ring, 5. Valve core, 6. Pin, 7. Ball, 8. Spring, 9. Second sealing ring, 10. Third Sealing ring, 11. Fourth sealing ring, 12. Fifth sealing ring, 13. Sixth sealing ring, 14. Seventh sealing ring, 15. Eighth sealing ring, 16. Lower joint, 17. Lock bolt, 18 . L-shaped groove.

a. Outer through hole, b. Inner through hole, c. Radial hole, d. Axial hole, e. Top of upper section, f. Main through hole, g. Side hole, h. Spool cavity, i. Thread Blind hole, j. middle outer wall of spool, k. stepped surface of spool.

Implementation

The present invention will be further described below in conjunction with the embodiments. It should be noted that in this article, words such as "upper" and "lower" are only used to facilitate the description of the accompanying drawings, and do not limit the direction in actual use, and are not necessarily No such actual relationship or order between these entities or operations is required or implied. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements, or also include elements inherent in such a process, method, article or equipment; part of the hydraulic, electric, wind and other driving mechanisms described in the present invention, without specifying the specific connection or movement mode, are all Belong to conventional prior art scheme.

As shown in Figures 1 to 12, a reversing joint for continuous sand flushing and well flushing includes an outer shell and a reversing assembly, and the outer shell is provided with a reversing assembly; the outer shell includes sequential connections from top to bottom. The upper joint 1, the outer cylinder 3, and the lower joint 16; the reversing assembly includes a sealing seat 2, a valve core 5, a spring 8, a first sealing ring 4, a second sealing ring 9, a third sealing ring 10, a first Four sealing rings 11, fifth sealing ring 12, sixth sealing ring 13, seventh sealing ring 14, eighth sealing ring 15; the sealing seat 2 is installed inside the upper joint 1, and the lower end of the valve core 5 is provided with a spring 8. The spring 8 is installed between the valve core 5 and the outer cylinder 3, and the spring 8 is connected to the lower joint 16; a through hole is set on the outer cylinder 3 as the outer through hole a, and it is set on the side of the lower section of the valve core 5 The through hole is used as the inner through hole b, the diameter of the inner through hole b is the same as that of the outer through hole a, and the valve core 5 moves axially inside the outer cylinder 3 to realize the flow path from the upper joint 1 to the inner cavity h of the valve core and the outer through hole Switching between opening and closing of the flow channel from a to the inner cavity of the spool h; when the inner through hole b and the outer through hole a are connected and coaxial, the flow channel from the outer through hole a to the inner cavity of the spool h is opened, and the spool 5 and the sealing Seat 2 contacts and seals, and the flow path from upper joint 1 to valve core inner cavity h is closed; when the inner through hole b and outer through hole a are misaligned, the outer through hole a to the valve core inner cavity h flow channel is closed, and the valve core The flow path between 5 and the sealing seat 2 is opened, and the flow path from the upper joint 1 to the inner cavity of the valve core h is opened.

As shown in Figure 1-4, the upper joint 1 is divided into upper and lower parts, the upper part of the upper joint 1 is provided with an internal thread, and the sealing seat 2 is provided with an external thread, and is installed on this section of the internal thread of the upper joint 1 On the top, the rotary seal seat 2 changes the axial relative position between the rotary seal seat 2 and the valve core 5, thereby changing the pressure of the spring 8; the inner lower part of the upper joint 1 is provided with an annular step, and there are at least eight steps in the circumferential direction of the annular step. There is a through hole along the axial direction, and an axially threaded blind hole is provided on the sealing seat 2. After the rotating sealing seat 2 reaches the designed position, the locking bolt 17 passes through the through hole on the annular step and the thread on the sealing seat 2. Connect to lock the sealing seat 2 to prevent the sealing seat 2 from rotating under the action of fluid shock and vibration.

The outside of the lower part of the upper joint 1 is provided with an external thread and a smooth surface from top to bottom, the external thread is used to connect with the internal thread of the outer cylinder 3, and a second sealing ring 9 is provided between the smooth surface and the contact surface of the outer cylinder 3 , the inner side of the lower part of the upper joint 1 is provided with four radial blind holes c, the radial holes c are opened from the inner side of the lower part of the upper joint 1 close to the upper end, and there is a wall in the wall that extends downwards and penetrates to the upper joint Axial hole d on the lower end surface of the lower part of 1;

The spool 5 includes three sections, upper, middle and lower. The upper section of the spool 5 is used to cooperate with the sealing seat 2. The outer diameter of the middle section of the spool 5 is smaller than the lower section of the spool 5. The outer wall j of the middle section of the spool 5 is in contact with the upper joint. The inner wall of the lower end of 1 is a clearance fit, and a first sealing ring 4 is provided between the middle outer wall b of the valve core 5 and the inner wall of the lower end of the upper joint 1, and the lower end of the valve core 5 is provided with a cylindrical structure.

The upper section of the spool 5 is a hollow columnar section below the arc-shaped surface, and a through hole is provided on the side of the hollow columnar section as a side hole g; in the middle of the sealing seat 2, a corresponding to the top e of the upper section of the spool 5 is provided. As the main through hole f, when the top e of the upper part of the valve core 5 touches the edge of the main through hole f in the middle of the sealing seat 2, the flow path from the upper joint 1 to the inner cavity h of the valve core is closed;

The bottom joint 16 is provided with an annular groove, and the bottom cylinder of the valve core 5 is installed inside the annular groove. 5 The step surface at the lower end is in contact, the lower end of the spring 8 is pressed against the end face of the lower joint 16, and an eighth sealing ring 15 is arranged between the inner wall surface of the bottom cylinder of the valve core 5 and the wall surface of the annular groove of the lower joint 16;

Outer cylinder 3 is provided with through-hole, as outer through-hole a, is provided with the same through-hole with the diameter of outer through-hole a in the side of the lower segment of valve core 5, as inner through-hole b, and the bottom of inner through-hole b and The seventh sealing ring 14 and the sixth sealing ring 13 for sealing with the outer cylinder 3 are respectively arranged above.

Preferably, three rows of balls 7 are arranged between the valve core 5 and the outer cylinder 3, and the balls 7 are embedded in the wall of the valve core 5 or the outer cylinder 3, and each row of balls 7 is preferably provided with eight equidistant balls in the circumferential direction. 7. It is beneficial to improve the coaxiality of the spool 5 relative to the outer cylinder 3, and the spool 5 and the outer cylinder 3 form a rolling pair, which reduces the frictional resistance of the spool 5 moving along the axial direction, and reduces the jamming of the spool 5 risk of death.

There are two threaded blind holes i in the middle of the valve core 5 in the circumferential direction, and two L-shaped grooves 18 are provided on the side of the outer cylinder 3, and the pin 6 passes through the L-shaped grooves 18 on the outer cylinder 3 and the threaded blind hole of the valve core 5 i is connected by thread; when the valve core 5 is stuck, the pin 6 can be manually operated to apply force along the axial direction of the valve core 5 to drive the valve core 5 to move in the L-shaped groove, thereby releasing the stuck.

The spool 5 and the outer cylinder 3 are respectively provided with a third sealing ring 10, a fourth sealing ring 11 and a fifth sealing ring 12 above and below the blind threaded hole i of the pin to realize the alignment between the spool 5 and the outer cylinder. 3. Seal up and down the L-shaped groove 18.

As shown in Figure 5-6, the lower joint 16 and the inner thread of the upper joint of the oil pipe are connected by threads to form a single piece, and the outer thread of the lower end joint of the oil pipe and the upper joint 1 are connected by threads to form a sand washing operation string. The wellhead is reversed and lowered into the self-sealing center and placed inside the casing.

As shown in Fig. 5 and Fig. 7, the arrow represents the flow direction of the sand washing fluid. When a single connection is made, the lower joint of the oil pipe is threaded with the upper joint 1 of the reversing joint 100 for continuous sand washing and well washing at the top of the sand washing string in the well. In the process of connecting a single root, the sand flushing pipeline A stops supplying sand flushing fluid and releases the pressure, and under the action of the spring 8, the arc-shaped surface h at the top of the valve core 5 is in contact with the sealing seat 2 The wall surface of the main through hole f of the main through hole f forms a line seal, where no fluid channel can be formed, that is, the flow channel from the upper joint 1 to the valve core inner cavity h is closed; at the same time, the sand washing liquid pressurized by the pump passes through the reversing valve, the sand washing pipe Road B flows into the wellhead and reversing self-sealing, through the wellhead reversing self-sealing annular chamber, the outer through hole a of the outer cylinder 3 flows into the inner through hole b of the valve core 5, the internal flow channel of the valve core 5 is the valve core cavity h, Then it enters the sand washing string below, and the flowback fluid formed after the flushing operation is completed returns to the wellhead through the annular space between the sand washing string and the casing, and flows into the sand removal device through the liquid outlet.

As shown in Figures 6 and 8, the arrows represent the flow direction of the sand washing fluid. When the sand washing pipe string is lowered normally, the uppermost end of the sand washing pipe string is installed with a reversing joint 100 for continuous sand washing and well washing. The upper joint 1 is connected to the sand washing pipe The sand washing fluid pressurized by the pump enters the upper joint 1 through the reversing valve and the sand washing pipeline A, and the pressure of the sand washing fluid acts on the arc-shaped surface of the top e of the valve core 5, resulting in a vertical Downward force P1; the sand washing fluid flows into the hydraulic cylinder formed by the valve core 5 and the outer cylinder 3 through the radial hole c arranged in the circumferential direction of the upper joint 1 and the axial hole d connected with the radial hole c, generating The vertical downward force P2 acting on the stepped surface k of the spool; under the action of the forces P1 and P2, the spool 5 moves vertically downward along the axis, the spring 8 is compressed and deformed, the spool 5 opens, and the sand is flushed The liquid enters the inner cavity h of the valve core 5 through the side hole j of the valve core 5, and then enters the sand washing pipe string below, and the flowback liquid that completes the flushing operation returns through the annular space between the sand washing pipe string and the casing At the wellhead, it flows into the sand removal device through the liquid outlet; at the same time, the outer through hole a of the outer cylinder 3 and the inner through hole b on the valve core 5 are misaligned, and a fluid channel cannot be formed.

As shown in Figures 9a to 9c, if the spool 5 of the reversing joint for continuous sand flushing that has not been lowered into the well is stuck, it cannot move upward or downward along the axis under the elastic force of the spring 8 and the pressure of the sand flushing fluid. During the movement, force can be applied to the pin 6 manually or mechanically, so as to drive the movement of the valve core 5 and realize the normal operation of the reversing joint for continuous sand flushing and well flushing. The top of the pin 6 is provided with at least one protruding tooth, on the upper side of the horizontal section of the L-shaped groove 18, there is a notch adapted to the teeth, and the width of the horizontal section of the L-shaped groove 18 matches the height of the pin 6 plus the tooth, The width of the vertical section matches the width of the pin 6 without teeth to ensure that the pin 6 moves smoothly in the L-shaped groove 18. The threaded hole e cooperates with the pin 6 , and when the pin 6 is tightened, it is ensured that the teeth of the pin 6 abut against the notch of the L-shaped groove 18 .

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes. Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the improvement of the technical solution of the present invention.

Claims (6)

1. The reversing joint for continuous sand flushing and well flushing is characterized by comprising an outer shell and a reversing assembly, wherein the reversing assembly is arranged in the outer shell; the outer shell comprises an upper connector, an outer cylinder and a lower connector which are sequentially connected from top to bottom; the reversing assembly comprises a sealing seat, a valve core, a spring, a first sealing ring, a second sealing ring, a third sealing ring, a fourth sealing ring, a fifth sealing ring, a sixth sealing ring, a seventh sealing ring and an eighth sealing ring; the sealing seat is arranged in the upper joint, a spring is arranged at the lower end of the valve core, the spring is arranged between the valve core and the outer cylinder, the spring is connected with the lower joint, and the cylinder at the lower end of the valve core is arranged in the annular groove of the lower joint; the upper section of the valve core is a hollow columnar section below the circular arc-shaped surface, and a through hole is formed in the side surface of the hollow columnar section and is used as a side hole; the middle part of the sealing seat is provided with a through hole corresponding to the top of the upper section of the valve core, and the through hole is used as a main through hole; the outer cylinder is provided with a through hole serving as an outer through hole; a through hole is arranged on the side surface of the lower section of the valve core and is used as an inner through hole, and the diameter of the inner through hole is the same as that of the outer through hole; the valve core moves axially in the outer cylinder to realize the switching of opening and closing of the upper joint to the valve core inner cavity flow passage and the outer through hole to the valve core inner cavity flow passage.

2. The reversing joint for continuous sand flushing and well flushing according to claim 1, wherein the upper joint is divided into an upper part and a lower part, an annular step is arranged at the lower part of the inner side of the upper joint, at least eight through holes along the axial direction are formed in the circumferential direction of the annular step, and an internal thread is arranged at the lower part of the upper joint; the outer wall surface of the sealing seat is provided with an external thread, and the sealing seat is provided with a blind hole along the axial thread; the external thread of the sealing seat is connected with the internal thread at the upper part of the upper joint, and the axial relative position of the sealing seat and the thread of the upper joint is adjusted by rotating the sealing seat, so that the opening pressure of the valve core can be adjusted; when the rotary sealing seat reaches the design position, the locking bolt passes through the through hole on the annular step of the upper joint to be connected with the thread on the sealing seat, so that the sealing seat is locked, and the sealing seat is prevented from rotating under the action of fluid impact and vibration.

3. The reversing joint for continuous sand flushing according to claim 2, wherein the outer side of the lower part of the upper joint is provided with an external thread and a smooth surface from top to bottom, the external thread is used for being connected with the inner side of the outer cylinder, a second sealing ring is arranged on the contact surface of the smooth surface and the outer cylinder, the inner side of the lower part of the upper joint is provided with four radial holes, the radial holes are outwards perforated from the inner side of the lower part of the upper joint close to the upper end, and an axial hole which downwards extends to penetrate the lower end surface of the lower part of the upper joint is arranged in the wall; the valve core comprises an upper section, a middle section and a lower section, the upper section of the valve core is used for forming linear seal with the sealing seat, the outer diameter of the middle section of the valve core is smaller than that of the lower section of the valve core, the outer wall of the middle section of the valve core is in clearance fit with the inner wall of the lower end of the upper joint, a first sealing ring is arranged between the outer wall of the middle section of the valve core and the inner wall of the lower end of the upper joint, and a second sealing ring is arranged between the outer wall surface of the lower end of the valve core and the outer cylinder; when the sand washing pipe column is normally lowered, sand washing liquid is injected from the upper part and passes through the main through hole of the sealing seat to generate vertical downward force acting on the step surface of the valve core; meanwhile, the sand washing liquid flows into the hydraulic cylinder formed by the valve core and the outer cylinder through the radial holes and the axial holes which are circumferentially arranged on the upper connector, and meanwhile, the pressure of the sand washing liquid acts on the circular arc surface at the top of the valve core to generate vertical downward force which is beneficial to the valve core to open and increase the opening of the valve core.

4. The reversing joint for continuous sand flushing according to claim 1, wherein at least two rows of balls are arranged between the valve core and the outer cylinder, the balls are embedded in the wall surface of the valve core or the outer cylinder, at least three balls are arranged in the circumferential direction of each row of balls, so that coaxiality of the valve core relative to the outer cylinder is improved, the valve core and the outer cylinder form a rolling pair, frictional resistance of the valve core along axial movement is reduced, and risk of locking of the valve core is reduced.

5. The reversing joint for continuous sand flushing and well flushing according to claim 1, wherein two threaded blind holes are formed in the middle circumference direction of the valve core, two L-shaped grooves are formed in the side face of the outer cylinder, and a pin penetrates through the L-shaped grooves in the outer cylinder and is connected with the threaded holes of the valve core through threads; the valve core and the outer cylinder are respectively provided with a fourth sealing ring and a fifth sealing ring above and below the pin threaded hole, and the fourth sealing ring and the fifth sealing ring are used for sealing the L-shaped groove; when the valve core is blocked, the pin can be manually operated to apply acting force along the axial direction of the valve core, so that the valve core is driven to move in the L-shaped groove, and the blocking is relieved; the groove surface on the upper side of the horizontal section of the L-shaped groove is provided with teeth, the cylindrical surface of the pin is provided with teeth meshed with the teeth on the groove surface on the horizontal section of the shaped groove, and the teeth on the cylindrical surface of the pin and the teeth on the shaped groove are meshed to form self-locking, so that a channel at the valve core sealing seat is in a normally open state, and the local pressure loss of sand washing liquid and valve core vibration are reduced.

6. The reversing joint for continuous sand flushing according to claim 1, wherein a through hole is formed in the outer cylinder and used as an outer through hole, the through hole formed in the side surface of the lower section of the valve core is the same as the outer through hole in diameter and used as an inner through hole, and a seventh sealing ring and a sixth sealing ring for sealing between the outer cylinder are respectively arranged below and above the inner through hole; the upper end of the lower joint is provided with a section of annular sinking groove, a bottom cylinder of the valve core is arranged in the annular sinking groove, a spring is arranged between the bottom cylinder of the valve core and the outer cylinder, the upper end of the spring is abutted against a step surface of the lower end of the valve core, the lower end of the spring is abutted against a step surface of the lower joint, and an eighth sealing ring is arranged between the bottom cylinder of the valve core and the wall surface of the annular sinking groove of the lower joint.