An oil and water well chemical fixed-point delivery device and its usage method

Abstract

The present invention relates to the technical field of scaling treatment for oil and water well tubulars, and in particular to a targeted delivery device for a chemical in an oil and water well and a method for using the device. The technical solution is as follows: a guide head is mounted at the lower end of a lower housing; a motor housing is mounted in the inner cavity of an upper housing, a motor is mounted in the motor housing, the output end of the motor is connected to a lead screw via a transmission shaft, the outer portion of the lead screw is engaged with a lead screw nut, the outer wall of the lead screw nut is engaged with a strip groove provided on the outer wall of the upper housing via a second screw, and the lead screw nut is driven to move along the lead screw by the rotation of the motor; the lower side of the lead screw nut is movably connected to the upper end of a connecting rod of a piston, the inner cavity of the lower housing contains chemical, the piston reciprocates up and down in the inner cavity of the lower housing, and pushes the chemical through a nozzle mounted on the guide head to be sprayed onto the scale or wax deposits on the inner wall of the downhole tubular. The present invention reduces the total amount of chemical used, avoids chemical residue in non-target areas, thereby reducing the risk of tubular corrosion and improving scaling efficiency and economy.

Description

Technical Field

[0001] The present invention relates to the technical field of scale treatment for oil and water well strings, and particularly to a chemical agent fixed-point injector for oil and water wells and a using method thereof. Background Art

[0002] During the process of oil exploitation, the inner wall of the oil and water well string is prone to form scale (such as calcium carbonate, sulfate, etc.) due to chemical reactions of water quality or oil-water mixture, resulting in the reduction of the inner diameter of the well string, the increase of flow resistance, and even the blockage of the production channel in severe cases. At present, the common scale removal methods in oil fields are mechanical scale removal or chemical scale removal methods. The mechanical scale removal method adopts mechanical scraping, and the construction time takes 3 - 5 days, and it has poor adaptability to complex well conditions; chemical scale removal mainly adopts the full well section cyclic injection of chemical agents, which has the following defects: First, chemical agent waste: the agent is dispersed throughout the well section, and the agent concentration in the target scaling area is insufficient, and excessive dosing is required to ensure the effect, resulting in high costs; Second, serious corrosion: excessive agents in long-term contact with the metal surface of the well string without scaling will accelerate the corrosion of the pipe material and shorten the service life of the well string; Third, low construction efficiency: multiple cyclic flushes are required, and the operation cycle is long, affecting the normal production of oil wells; In short, they all cannot accurately act on the scaling points of the well string and have poor adaptability to complex well conditions. Therefore, there is an urgent need for a technology that can accurately deliver agents, precisely control the dosage, and reduce corrosion. Summary of the Invention

[0003] The purpose of the present invention is to address the above-mentioned defects existing in the prior art, and provide a chemical agent fixed-point injector for oil and water wells and a using method thereof. Through the directional injection technology, the agent is accurately delivered to the scaling part of the well string, reducing the total amount of agent used, avoiding the agent residue in non-target areas, thereby reducing the risk of well string corrosion and improving the scale removal efficiency and economy.

[0004] A chemical agent fixed-point delivery device for oil and water wells mentioned in the present invention has the following technical solution: It includes a releasing cap and an upper housing. The releasing cap is installed at the upper end of the upper housing. Among them, it also includes a motor, a motor housing, a transmission shaft, an intermediate connector, a universal joint, a lead screw nut, a lead screw, a piston, a lower housing, a nozzle, and a guiding head. The lower end of the upper housing is connected to the lower housing, and the guiding head is installed at the lower end of the lower housing; the inner cavity of the upper housing installs the motor housing, and the motor is installed inside the motor housing. The output end of the motor is connected to the transmission shaft, and the transmission shaft passes through the intermediate connector and is connected to the lead screw through the universal joint. The outside of the lead screw is matched with the lead screw nut, and the outer wall of the lead screw nut is matched with a strip-shaped groove provided on the outer wall of the upper housing through a second screw. The rotation movement of the motor drives the lead screw nut to move along the lead screw; the lower side of the lead screw nut is movably connected to the upper end of the connecting rod of the piston. The piston is located in the inner cavity of the lower housing, and the chemical agent is contained in the inner cavity of the lower housing. The piston reciprocates up and down in the inner cavity of the lower housing, pushing the chemical agent downward along the lower housing and spraying it onto the scaling or waxing part on the inner wall of the downhole tubing through the nozzle installed on the guiding head.

[0005] Preferably, the above-mentioned piston includes a connecting rod, a first upper joint, a connecting hole, a liquid changing groove, a piston head, and a one-way valve installation cavity. One end of the connecting rod is the first upper joint, and the other end is connected to the piston head; one or more connecting holes are provided at the first upper joint and are connected to the lead screw nut through bolts; multiple liquid changing grooves are provided on the outer wall of the connecting rod, and a one-way valve installation cavity is provided inside the piston head for installing the first one-way valve; a limiting protrusion is provided on the upper side of the connecting rod, and more than one set of sealing ring grooves are provided on the outer side of the piston head for installing sealing rings.

[0006] Preferably, the above-mentioned lead screw includes a lead screw body, a second upper joint, a lower joint, an external thread, a positive spiral thread, and a reverse circulation thread. A second upper joint is provided at one end of the lead screw body, and a lower joint is provided at the other end. An external thread is provided on the outside of the second upper joint, and a commutation track composed of a positive spiral thread and a reverse circulation thread is provided on the outer wall of the lead screw body. The lead screw nut moves forward along the positive spiral thread and moves backward along the reverse circulation thread.

[0007] Preferably, the above-mentioned lead screw nut includes a first fixing hole, a second fixing hole, a nut body, a lead screw connection cavity, a piston rod connection cavity, and a half-moon key groove. Axially in the middle of the nut body, there are a lead screw connection cavity and a piston rod connection cavity. In the vertical direction of the lead screw connection cavity, there is a half-moon key groove for installing a half-moon key. Radially on the outer wall of the nut body, there are a first fixing hole and a second fixing hole. The nut body is connected to the strip groove on the outer wall of the upper shell by installing a second screw through the first fixing hole. A half-moon key and a limit bolt are installed through the half-moon key groove, so that the half-moon key is connected in cooperation with the reversing track of the lead screw. The second screw on the strip groove is used to limit the rotation of the lead screw nut and its movement along the position of the strip groove; A bolt is installed in the second fixing hole to connect the connection hole of the piston with the second fixing hole, realizing the connection between the first upper joint of the piston and the nut body, and further realizing the reciprocating movement of the piston driven by the lead screw nut.

[0008] Preferably, the above-mentioned half-moon key includes a half-moon key body, a body tail handle, and an arc-shaped half-moon. A cylindrical body tail handle is provided at the tail of the half-moon key body, and an arc-shaped half-moon is provided at the front end of the half-moon key body, which cooperates with the reversing track of the lead screw through the arc-shaped half-moon.

[0009] Preferably, a limit bolt is installed outside the above-mentioned half-moon key. A cylindrical end is provided at the front end of the limit bolt, and the cylindrical end is sleeved outside the body tail handle. External threads are provided on the outside of the limit bolt for threaded connection with the half-moon key groove.

[0010] Preferably, the front end of the above-mentioned arc-shaped half-moon is an arc-shaped groove structure for cooperating with the reversing track of the lead screw. Arc-shaped protrusions are provided on both sides of the arc-shaped half-moon, which is convenient for reversing in the reversing track.

[0011] Preferably, the connection hole of the first upper joint of the above-mentioned piston is fixedly connected to the second fixing hole through a bolt, realizing the connection and fixation between the piston and the lead screw nut. Further, driven by the movement of the lead screw nut, the position of the piston is driven to move.

[0012] Preferably, the above-mentioned guide head includes a guide head body, a guide head joint, a pressure balance hole, a check valve spring installation hole, external threads, a seal ring installation groove, a nozzle installation hole, a check valve installation cavity, and a support frame installation cavity. The inner cavity of the guide head body is successively a pressure balance hole, a check valve spring installation hole, a check valve installation cavity, and a support frame installation cavity from bottom to top. A check valve spring is installed in the check valve spring installation hole, a second check valve is installed in the check valve installation cavity, and a support frame is installed in the support frame installation cavity; A group or more of nozzle installation holes are provided on the outer peripheral wall of the upper part of the guide head body for installing nozzles; A guide head joint is provided at the upper part of the guide head body. External threads and a seal ring installation groove are provided on the outside of the guide head joint. The external threads are used for threaded connection with the lower shell, and the seal ring installation groove is used for installing a seal ring.

[0013] The usage method of the chemical agent fixed-point delivery device for oil and water wells mentioned in the present invention includes the following processes:

[0014] After the chemical agent fixed-point delivery device for oil and water wells is lowered to the target position in the oil well shaft, start the motor and control the motor to run at a low speed. The output end of the motor drives the lead screw to rotate through a transmission shaft and a universal joint. Since a lead screw nut is installed outside the lead screw, and the outer wall of the lead screw nut is matched with the strip-shaped groove provided on the outer wall of the upper shell through a second screw, and the keyway installed in the lead screw nut is matched with the positive spiral thread of the reversing track on the lead screw. In this way, under the rotational movement of the lead screw, the lead screw nut moves downward along the strip-shaped groove; in addition, since the lead screw nut is also connected to the piston, the piston is driven to move downward, thereby pushing the chemical agent downward along the lower shell. At this time, the first one-way valve is in a closed state, and the chemical agent pushes the second one-way valve to move downward. The chemical agent is sprayed onto the scaling or waxing part on the inner wall of the downhole tubing through the nozzle installed on the guide head; after a period of time, the piston head is pushed to the bottom of the lower shell to complete part of the injection of the chemical agent;

[0015] Then, the motor continues to rotate, and the keyway enters the reverse circulation thread of the reversing track on the lead screw, thereby driving the lead screw nut to move reversely along the lead screw; at this time, the first one-way valve is in an open state, and the second one-way valve returns to its original position under the action of the one-way valve spring, blocking the channel for the chemical agent to be sprayed; and at this time, the liquid in the wellbore enters the inner cavity of the upper shell through the strip-shaped groove on the outer wall of the upper shell, and then enters the chemical agent cavity below the piston through the liquid-changing groove on the outer wall of the connecting rod and the first one-way valve until the piston moves up to the top dead center to stop the liquid from entering;

[0016] After that, the keyway continues to repeat the commutation in the commutation track, and the piston moves downward again, and the mixed chemical agent is continuously sprayed onto the scaling or waxing part on the inner wall of the downhole tubing through the nozzle. After multiple cycles, the chemical agent is completely discharged.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] In the present invention, the motor drives the lead screw to rotate, thereby driving the lead screw nut to make a reciprocating movement, and further driving the piston connected to the lead screw nut to make a reciprocating movement, accurately delivering the chemical agent in the chemical agent cavity to the scaling part through the nozzle, reducing the total amount of chemical agent used, avoiding the chemical agent residue in the non-target area, thereby reducing the risk of pipe string corrosion and improving the descaling efficiency and economy; in addition, the keyway adopted in the present invention is matched with the commutation track of the lead screw, which can realize the reciprocating movement of the lead screw nut; moreover, the liquid in the wellbore enters the inner cavity of the upper shell through the strip-shaped groove on the outer wall of the upper shell, and then enters the chemical agent cavity below the piston through the liquid-changing groove on the outer wall of the connecting rod and the first one-way valve, which can realize the mixing of the chemical agent, and through multiple reciprocating movements, the complete injection of the chemical agent is realized, improving the use efficiency of the chemical agent. Description of the Drawings

[0019] Figure 1 is a schematic structural view of the piston of the present invention at the top dead center;

[0020] Figure 2 is a schematic structural view of the piston of the present invention at the bottom dead center;

[0021] Figure 3 is a schematic structural view of the piston of the present invention;

[0022] Figure 4 is Figure 3 a schematic view of the C-C cross-section in

[0023] Figure 5 is a schematic structural view of the lead screw of the present invention;

[0024] Figure 6 is a schematic structural view of the lead screw nut of the present invention;

[0025] Figure 7 is Figure 6 a schematic view of the A-A cross-section in

[0026] Figure 8 is Figure 7 a schematic structural view of the installation of the limit bolt in

[0027] Figure 9 is a schematic structural view of the gib key;

[0028] Figure 10 is a schematic side view of the gib key;

[0029] Figure 11 is a schematic top view of the gib key;

[0030] Figure 12 is a schematic external view of the guide head

[0031] Figure 13 is a schematic structural view of the guide head;

[0032] Figure 14 is Figure 13 a schematic view of the B-B cross-section in

[0033] In the above figure: the releasing protection cap 1, the upper housing 2, the motor 3, the motor housing 4, the transmission shaft 5, the intermediate connector 6, the first retaining ring 7, the retaining sleeve 8, the universal joint 9, the lead screw nut 10, the lead screw 11, the piston 12, the check valve gland 13, the lower housing 14, the support frame 15, the nozzle 16, the second one-way valve 17, the one-way valve spring 18, the guide head 19, the first one-way valve 20, the sealing ring 21, the second retaining ring 22, the second screw 23, the third screw 24, the first thrust bearing 25, the second thrust bearing 26, the shaft snap ring 27, the cross recessed countersunk head screw 28, the hole snap ring 29, the single-core blue socket 30, the coupling 31, the motor set screw 32, the first screw 33, the strip groove 34, the half-moon key 35, the limit bolt 36;

[0034] The first fixing hole 10.1, the second fixing hole 10.2, the nut body 10.3, the lead screw connection cavity 10.4, the piston rod connection cavity 10.5, the half-moon key groove 10.6, the lead screw main body 11.1, the second upper joint 11.2, the lower joint 11.3, the external thread 11.4, the positive spiral thread 11.5, the reverse circulation thread 11.6, the connecting rod 12.1, the limit protrusion 12.2, the first upper joint 12.3, the connection hole 12.4, the liquid change groove 12.5, the piston head 12.6, the one-way valve installation cavity 12.7, the sealing ring groove 12.8, the guide head main body 19.1, the guide head joint 19.2, the pressure balance hole 19.3, the one-way valve spring installation hole 19.4, the external thread 19.5, the sealing ring installation groove 19.6, the nozzle installation hole 19.7, the one-way valve installation cavity 19.8, the support frame installation cavity 19.9, the half-moon key main body 35.1, the main body tail handle 35.2, the arc half-moon 35.3. Detailed implementation manners

[0035] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0036] Example 1, referring to Figures 1 - 14The present invention mentions an oil and water well medicine fixed-point delivery device, including a hand-release cap 1 and an upper shell 2. The upper end of the upper shell 2 is installed with a single-core flange socket 30 through a hole using an elastic retaining ring 29, and the hand-release cap 1 is installed on the outside. It also includes a motor 3, a motor housing 4, a transmission shaft 5, an intermediate connector 6, a universal joint 9, a screw nut 10, a screw 11, a piston 12, a lower shell 14, a nozzle 16, and a guide head 19. The lower end of the upper shell 2 is connected to the lower shell 14, and the guide head 19 is installed at the lower end of the lower shell 14; the inner cavity of the upper shell 2 is installed with a cross-slot countersunk screw 28, the motor 3 is installed in the motor housing 4, and the motor 3 is fixed to the motor housing 4 by a motor set screw 32, and the output end of the motor 3 is connected to the transmission shaft 5 through a coupling 31. The transmission shaft 5 passes through the intermediate connector 6 and is connected to the lead screw 11 through the universal joint 9, and the intermediate connector 6 is fixed by a first screw 33. The outside of the lead screw 11 cooperates with the lead screw nut 10, and the outer wall of the lead screw nut 10 cooperates with the strip groove 34 provided on the outer wall of the upper shell 2 through the second screw 23. The lead screw nut 10 is driven to move along the lead screw 11 through the rotation of the motor 3; the lower side of the lead screw nut 10 is movably connected to the upper end of the connecting rod 12.1 of the piston 12, and the piston 12 is located in the inner cavity of the lower shell 14, and the inner cavity of the lower shell 14 is filled with medicine. The piston 12 reciprocates up and down in the inner cavity of the lower shell 14, pushing the medicine downward along the lower shell 14, and spraying it to the scale or wax accumulation on the inner wall of the downhole pipe through the nozzle 16 installed on the guide head 19.

[0037] Among them, the first thrust bearing 25 and the second thrust bearing 26 are installed on the upper part of the transmission shaft 5, and the first retaining ring 7, the sealing ring 21 and the retaining sleeve 8 are installed between the lower part of the transmission shaft 5 and the intermediate connector 6; the outer side of the intermediate connector 6 is connected to the motor housing 4 through the third screw 24, and the lower part of the coupling 31 is provided with a shaft elastic retaining ring 27 to reduce noise and friction; the second retaining ring 22 is installed at the lower part of the universal joint 9.

[0038] Reference Figure 3 and Figure 4 The piston 12 mentioned in the present invention includes a connecting rod 12.1, a first upper joint 12.3, a connecting hole 12.4, a liquid exchange groove 12.5, a piston head 12.6, and a one-way valve installation cavity 12.7. One end of the connecting rod 12.1 is the first upper joint 12.3, and the other end is connected to the piston head 12.6; there is one or more connecting holes 12.4 at the first upper joint 12.3, which are connected to the screw nut 10 by bolts; a plurality of liquid exchange grooves 12.5 are provided on the outer wall of the connecting rod 12.1, and a one-way valve installation cavity 12.7 is provided inside the piston head 12.6 for installing a first one-way valve 20, wherein a check valve gland 13 is installed at the lower part of the piston head 12.6.

[0039] In use, when the piston 12 pushes the medicament downward, the first one-way valve 20 is in the closed state. After the medicament is compressed, it is sprayed through the nozzle 16 to the scaling or waxing part on the inner wall of the downhole tubular. When the piston 12 returns upward, the first one-way valve 20 is in the open state. At this time, the liquid in the wellbore enters the inner cavity of the upper housing 2 through the strip-shaped groove 34 on the outer wall of the upper housing 2, and then enters the medicament cavity below the piston 12 through the liquid-changing groove 12.5 on the outer wall of the connecting rod 12.1 and the first one-way valve 20. Then, the piston 12 repeats moving downward, and continues to spray the mixed medicament through the nozzle 16 to the scaling or waxing part on the inner wall of the downhole tubular until the medicament is completely ejected.

[0040] Wherein, a limiting protrusion 12.2 is provided on the upper side of the connecting rod 12.1, and more than one set of sealing ring grooves 12.8 are provided on the outer side of the piston head 12.6 for installing the sealing ring 21.

[0041] Refer to Figure 5 , the lead screw 11 mentioned in the present invention includes a lead screw body 11.1, a second upper joint 11.2, a lower joint 11.3, an external thread 11.4, a positive spiral thread 11.5, and a reverse circulation thread 11.6. A second upper joint 11.2 is provided at one end of the lead screw body 11.1, and a lower joint 11.3 is provided at the other end. An external thread 11.4 is provided on the outer side of the second upper joint 11.2. A reversing track composed of a positive spiral thread 11.5 and a reverse circulation thread 11.6 is provided on the outer wall of the lead screw body 11.1. The lead screw nut 10 moves forward along the positive spiral thread 11.5 and moves backward along the reverse circulation thread 11.6.

[0042] Refer to Figures 6 - 8, the lead screw nut 10 mentioned in the present invention includes a first fixing hole 10.1, a second fixing hole 10.2, a nut body 10.3, a lead screw connection cavity 10.4, a piston rod connection cavity 10.5, and a half-moon key groove 10.6. An axial lead screw connection cavity 10.4 and a piston rod connection cavity 10.5 are provided in the middle of the nut body 10.3. A half-moon key groove 10.6 is provided in the vertical direction of the lead screw connection cavity 10.4 for installing the half-moon key 35. A first fixing hole 10.1 and a second fixing hole 10.2 are radially provided on the outer wall of the nut body 10.3. The nut body 10.3 is connected to the strip groove 34 on the outer wall of the upper housing 2 by installing a second screw 23 through the first fixing hole 10.1. The half-moon key 35 and the limit bolt 36 are installed through the half-moon key groove 10.6, so that the half-moon key 35 is connected in cooperation with the reversing track of the lead screw 11. The second screw 23 on the strip groove 34 is used to limit the rotation of the lead screw nut 10 and move along the position of the strip groove 34; the second fixing hole 10.2 installs a bolt to connect the connection hole 12.4 of the piston 12 with the second fixing hole 10.2 to realize the connection between the first upper joint 12.3 of the piston 12 and the nut body 10.3, and further realize the reciprocating movement of the piston 12 driven by the lead screw nut 10.

[0043] Referring to Figures 9 - 11 , the half-moon key 35 mentioned in the present invention includes a half-moon key body 35.1, a body tail handle 35.2, and an arc-shaped half-moon 35.3. A cylindrical body tail handle 35.2 is provided at the tail of the half-moon key body 35.1, and an arc-shaped half-moon 35.3 is provided at the front end of the half-moon key body 35.1, and is connected in cooperation with the reversing track of the lead screw 11 through the arc-shaped half-moon 35.3.

[0044] Among them, a limit bolt 36 is installed on the outer side of the above-mentioned half-moon key 35. The front end of the limit bolt 36 is provided with a cylindrical end, and the cylindrical end is sleeved on the outer side of the body tail handle 35.2. The outer side of the limit bolt 36 is provided with an external thread for thread connection with the half-moon key groove 10.6.

[0045] The front end of the above-mentioned arc-shaped half-moon 35.3 is an arc-shaped groove structure for connecting with the reversing track of the lead screw 11. The two sides of the arc-shaped half-moon 35.3 are arc-shaped convex structures, which are convenient for reversing in the reversing track.

[0046] Among them, the connection hole 12.4 of the first upper joint 12.3 of the above-mentioned piston 12 is fixedly connected with the second fixing hole 10.2 through a bolt, realizing the connection and fixation between the piston 12 and the lead screw nut 10, and further driving the piston 12 to move its position driven by the movement of the lead screw nut 10.

[0047] Referring to Figures 12 - 14, the guide head 19 mentioned in the present invention includes a guide head body 19.1, a guide head joint 19.2, a pressure balance hole 19.3, a check valve spring mounting hole 19.4, an external thread 19.5, a sealing ring mounting groove 19.6, a nozzle mounting hole 19.7, a check valve mounting cavity 19.8, and a support frame mounting cavity 19.9. The inner cavity of the guide head body 19.1 is successively the pressure balance hole 19.3, the check valve spring mounting hole 19.4, the check valve mounting cavity 19.8, and the support frame mounting cavity 19.9 from bottom to top. A check valve spring 18 is installed in the check valve spring mounting hole 19.4, a second check valve 17 is installed in the check valve mounting cavity 19.8, and a support frame 15 is installed in the support frame mounting cavity 19.9. A set of or more nozzle mounting holes 19.7 are provided on the outer peripheral wall of the upper part of the guide head body 19.1 for installing nozzles 16. A guide head joint 19.2 is provided on the upper part of the guide head body 19.1. An external thread 19.5 and a sealing ring mounting groove 19.6 are provided on the outside of the guide head joint 19.2. The external thread 19.5 is used for threaded connection with the lower housing 14, and the sealing ring mounting groove 19.6 is used for installing a sealing ring 21.

[0048] The usage method of the oil well and water well chemical agent fixed-point injector mentioned in the present invention includes the following processes:

[0049] I. Chemical agent injection:

[0050] Open the guide head 19, fill the chemical agent chamber of the lower housing 14 with the chemical agent. After the chemical agent is filled, connect the guide head 19.

[0051] II. Transportation:

[0052] During transportation of the present invention, it is necessary to pay attention to whether there is chemical agent flowing out from the guide head 19 at the lower end. A sealing bag can be tied outside the guide head 19 to prevent chemical agent leakage.

[0053] III. Placement and chemical agent injection:

[0054] Lower the chemical agent fixed-point delivery device mentioned in the present invention to the target position in the oil wellbore, start the motor 3, and control the motor 3 to operate at a lower speed. The output end of the motor 3 drives the lead screw 11 to rotate through the transmission shaft 5 and the universal joint 9. Since the lead screw nut 10 is installed outside the lead screw 11, and the outer wall of the lead screw nut 10 is matched with the strip groove 34 provided on the outer wall of the upper housing 2 through the second screw 23, and the half-moon key 35 installed in the lead screw nut 10 is matched with the positive spiral thread 11.5 of the reversing track on the lead screw 11. In this way, under the rotational movement of the lead screw 11, the lead screw nut 10 moves downward along the strip groove 34; in addition, since the lead screw nut 10 is also connected to the piston 12, the piston 12 is driven to move downward, thereby pushing the chemical agent downward along the lower housing 14. At this time, the first one-way valve 20 is in a closed state, and the chemical agent pushes the second one-way valve 17 to move downward. The chemical agent is sprayed onto the scaling or waxing part of the inner wall of the downhole tubing through the nozzle 16 installed on the guiding head 19; after a period of time, the piston head 12.6 reaches the bottom of the lower housing 14, and part of the chemical agent injection is completed;

[0055] Then, the motor 3 continues to rotate, and the half-moon key 35 enters the reverse circulation thread 11.6 of the reversing track on the lead screw 11, thereby driving the lead screw nut 10 to move in the reverse direction along the lead screw 11; at this time, the first one-way valve 20 is in an open state, and the second one-way valve 17 returns to its original position under the action of the one-way valve spring 18, blocking the chemical agent spraying channel; and at this time, the liquid in the wellbore enters the inner cavity of the upper housing 2 through the strip groove 34 on the outer wall of the upper housing 2, and then enters the chemical agent cavity below the piston 12 through the liquid changing groove 12.5 on the outer wall of the connecting rod 12.1 and the first one-way valve 20 until the piston 12 moves up to the top dead center and the liquid intake stops;

[0056] After that, the half-moon key 35 continues to reverse in the reversing track, and the piston 12 moves downward again, continuing to spray the mixed chemical agent onto the scaling or waxing part of the inner wall of the downhole tubing through the nozzle 16. After multiple cycles until the chemical agent is completely discharged.

[0057] As mentioned above, it is only a part of the preferred embodiments of the present invention. Any person skilled in the art may modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations made according to the technical solutions of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A chemical fixed-point injector for oil and water wells, comprising a releasing cap (1) and an upper housing (2). The releasing cap (1) is installed at the upper end of the upper housing (2). It is characterized in that: It further includes a motor (3), a motor housing (4), a transmission shaft (5), an intermediate connector (6), a universal joint (9), a lead screw nut (10), a lead screw (11), a piston (12), a lower housing (14), a nozzle (16), and a guide head (19). The lower end of the upper housing (2) is connected to the lower housing (14), and the guide head (19) is installed at the lower end of the lower housing (14); the motor housing (4) is installed in the inner cavity of the upper housing (2), the motor (3) is installed in the motor housing (4), the output end of the motor (3) is connected to the transmission shaft (5), the transmission shaft (5) passes through the intermediate connector (6) and is connected to the lead screw (11) through the universal joint (9), the outside of the lead screw (11) is matched with the lead screw nut (10), the outer wall of the lead screw nut (10) is matched with a strip groove (34) provided on the outer wall of the upper housing (2) through a second screw (23), and the rotation of the motor (3) drives the lead screw nut (10) to move along the lead screw (11); the lower side of the lead screw nut (10) is movably connected to the upper end of a connecting rod (12.1) of the piston (12), the piston (12) is located in the inner cavity of the lower housing (14), and a chemical agent is contained in the inner cavity of the lower housing (14). The piston (12) reciprocates up and down in the inner cavity of the lower housing (14), pushing the chemical agent downward along the lower housing (14), and spraying it onto the scaling or wax deposition on the inner wall of the downhole tubing through the nozzle (16) installed on the guide head (19) at a fixed point; The lead screw (11) includes a lead screw body (11.1), a second upper joint (11.2), a lower joint (11.3), an external thread (11.4), a positive spiral thread (11.5), and a reverse circulation thread (11.6). A second upper joint (11.2) is provided at one end of the lead screw body (11.1), and a lower joint (11.3) is provided at the other end. An external thread (11.4) is provided on the outside of the second upper joint (11.2). A commutation track composed of a positive spiral thread (11.5) and a reverse circulation thread (11.6) is provided on the outer wall of the lead screw body (11.1). The lead screw nut (10) moves forward along the positive spiral thread (11.5) and moves backward along the reverse circulation thread (11.6); The lead screw nut (10) includes a first fixing hole (10.1), a second fixing hole (10.2), a nut body (10.3), a lead screw connection cavity (10.4), a piston rod connection cavity (10.5) and a half-moon keyway (10.6). In the middle of the nut body (10.3), the lead screw connection cavity (10.4) and the piston rod connection cavity (10.5) are axially provided. In the vertical direction of the lead screw connection cavity (10.4), the half-moon keyway (10.6) is provided for installing a half-moon key (35). On the outer wall of the nut body (10.3), the first fixing hole (10.1) and the second fixing hole (10.2) are radially provided. The nut body (10.3) is connected to the strip groove (34) on the outer wall of the upper housing (2) by installing a second screw (23) through the first fixing hole (10.1). The half-moon key (35) and a limit bolt (36) are installed through the half-moon keyway (10.6) so that the half-moon key (35) is connected to the reversing track of the lead screw (11). The second screw (23) on the strip groove (34) is used to limit the rotation of the lead screw nut (10) and move along the position of the strip groove (34). A bolt is installed in the second fixing hole (10.2) to connect the connection hole (12.4) of the piston (12) with the second fixing hole (10.2) to realize the connection between the first upper joint (12.3) of the piston (12) and the nut body (10.3), and further realize the reciprocating movement of the piston (12) driven by the lead screw nut (10). The half-moon key (35) includes a half-moon key body (35.1), a body tail handle (35.2), and an arc-shaped half-moon (35.3). A cylindrical body tail handle (35.2) is provided at the tail of the half-moon key body (35.1). An arc-shaped half-moon (35.3) is provided at the front end of the half-moon key body (35.1) and is matched with the reversing track of the lead screw (11) through the arc-shaped half-moon (35.3). The front end of the arc-shaped half-moon (35.3) is an arc-shaped groove structure for matching with the reversing track of the lead screw (11). The two sides of the arc-shaped half-moon (35.3) are arc-shaped convex structures, which are convenient for reversing in the reversing track.

2. The chemical fixed-point injector for oil and water wells according to claim 1, wherein: The piston (12) includes a connecting rod (12.1), a first upper joint (12.3), a connection hole (12.4), a liquid changing groove (12.5), a piston head (12.6), and a one-way valve installation cavity (12.7). One end of the connecting rod (12.1) is the first upper joint (12.3), and the other end is connected to the piston head (12.6). One or more connection holes (12.4) are provided at the first upper joint (12.3) and are connected to the lead screw nut (10) by bolts. A plurality of liquid changing grooves (12.5) are provided on the outer wall of the connecting rod (12.1). A one-way valve installation cavity (12.7) is provided inside the piston head (12.6) for installing a first one-way valve (20). A limit protrusion (12.2) is provided on the upper side of the connecting rod (12.1). One or more seal ring grooves (12.8) are provided on the outer side of the piston head (12.6) for installing a seal ring (21).

3. The chemical fixed-point injector for oil and water wells according to claim 2, characterized in that: A limit bolt (36) is installed on the outer side of the crescent key (35). The front end of the limit bolt (36) is provided with a cylindrical end, and the cylindrical end is sleeved on the outer side of the body tail handle (35.2). The outer side of the limit bolt (36) is provided with an external thread for threaded connection with the crescent key groove (10.6).

4. The chemical agent fixed-point injector for oil and water wells according to claim 3, characterized in that: The connection hole (12.4) of the first upper joint (12.3) of the piston (12) is fixedly connected to the second fixing hole (10.2) by a bolt, so as to realize the connection and fixation between the piston (12) and the lead screw nut (10). Furthermore, driven by the movement of the lead screw nut (10), the piston (12) is driven to move its position.

5. The chemical agent fixed-point injector for oil and water wells according to claim 4, characterized in that: The guide head (19) includes a guide head body (19.1), a guide head joint (19.2), a pressure balance hole (19.3), a check valve spring installation hole (19.4), an external thread (19.5), a sealing ring installation groove (19.6), a nozzle installation hole (19.7), a check valve installation cavity (19.8) and a support frame installation cavity (19.9). The inner cavity of the guide head body (19.1) is, from bottom to top, the pressure balance hole (19.3), the check valve spring installation hole (19.4), the check valve installation cavity (19.8) and the support frame installation cavity (19.9). A check valve spring (18) is installed in the check valve spring installation hole (19.4), a second check valve (17) is installed in the check valve installation cavity (19.8), and a support frame (15) is installed in the support frame installation cavity (19.9); A set of or more nozzle installation holes (19.7) are provided on the outer peripheral wall of the upper part of the guide head body (19.1) for installing nozzles (16); A guide head joint (19.2) is provided on the upper part of the guide head body (19.1). An external thread (19.5) and a sealing ring installation groove (19.6) are provided on the outer side of the guide head joint (19.2). The external thread (19.5) is used for threaded connection with the lower housing (14), and the sealing ring installation groove (19.6) is used for installing a sealing ring (21).

6. The method for using the chemical fixed-point injector for oil and water wells according to claim 5, characterized in that: It includes the following processes: After the chemical agent fixed-point delivery device for oil and water wells is lowered to the target position in the oil wellbore, start the motor (3), control the motor (3) to run at a low speed. The output end of the motor (3) drives the lead screw (11) to rotate through the transmission shaft (5) and the universal joint (9). Since a lead screw nut (10) is installed outside the lead screw (11), and the outer wall of the lead screw nut (10) is matched with the strip-shaped groove (34) provided on the outer wall of the upper housing (2) through the second screw (23), and the half-moon key (35) installed in the lead screw nut (10) is matched with the positive helical thread (11.5) of the reversing track on the lead screw (11). In this way, under the rotational movement of the lead screw (11), the lead screw nut (10) moves downward along the strip-shaped groove (34); in addition, since the lead screw nut (10) is also connected to the piston (12), the piston (12) is driven to move downward, thereby pushing the chemical agent downward along the lower housing (14). At this time, the first one-way valve (20) is in a closed state, and the chemical agent pushes the second one-way valve (17) to move downward. The chemical agent is sprayed onto the scaling or wax deposition on the inner wall of the downhole tubing through the nozzle (16) installed on the guide head (19); after a period of time, the piston head (12.6) is pushed to the bottom of the lower housing (14), and part of the chemical agent is injected; Then, the motor (3) continues to rotate, and the half-moon key (35) enters the reverse circulation thread (11.6) of the reversing track on the lead screw (11), thereby driving the lead screw nut (10) to move in the reverse direction along the lead screw (11); at this time, the first one-way valve (20) is in an open state, and the second one-way valve (17) returns to its original position under the action of the one-way valve spring (18), blocking the channel for the chemical agent to be sprayed; and at this time, the liquid in the wellbore enters the inner cavity of the upper housing (2) through the strip-shaped groove (34) on the outer wall of the upper housing (2), and then enters the chemical agent chamber below the piston (12) through the liquid-changing groove (12.5) on the outer wall of the connecting rod (12.1) and the first one-way valve (20), until the piston (12) moves up to the top dead center and stops the liquid from entering; After that, the half-moon key (35) continues to repeat the commutation in the commutation track, and the piston (12) moves downward again, and the mixed chemical agent is continuously sprayed onto the scaling or wax deposition on the inner wall of the downhole tubing through the nozzle (16). After multiple cycles until the chemical agent is completely discharged.

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