A method and apparatus for deep wellbore dosing

Abstract

The application provides a wellbore deep medicine adding method and device, which comprises a ground adding jack, a ground pipeline, a single flow valve, an injection well head, a tubing, a delivery-injection medicine pipe, a pumping unit, a pipe clamp, an injection-mixer, a screen pipe and a plug; the working method of the wellbore deep medicine adding device is as follows: the medicine in the ground adding jack is pressurized and then enters the delivery-injection medicine pipe; when the pressure at the bottom of the medicine column in the delivery-injection medicine pipe is greater than the liquid column in the tubing plus the opening pressure of the injection-mixer, the medicine enters the injection-mixer and is fully mixed with the liquid flow in the tubing under the shunt-mixing effect of the injection-mixer to form liquid-medicine mixed liquid; when the liquid-medicine mixed liquid enters the pumping unit, the liquid-medicine mixed liquid reaches the well head under the lifting effect of the pumping unit, and the medicine plays a role on the tubing and the liquid flow above the injection-mixer. The application solves the problems of poor continuity, quantification, controllability and well condition adaptability of oil and gas well wellbore medicine adding, improves the accuracy and reliability of wellbore medicine adding, and further improves the medicine adding effect.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas production-lifting technology, and in particular relates to a method and device for deep well chemical injection. Background Technology

[0002] During oil and gas well production, problems such as corrosion, scaling, and wax buildup are common. Corrosion from formation fluids not only damages tools such as tubing, casing, and downhole pumps, but also leads to frequent well workover operations. Scaling and wax buildup increase the roughness of pipes, reduce the effective flow area, increase the production pressure differential, decrease oil and gas well production, and may even clog the tubing, causing well shutdowns and severely impacting normal production. In particular, for high-pour-point and heavy oils, crude oil is prone to solidification in the wellbore or its high viscosity affects its fluidity, hindering normal oil and gas well production.

[0003] Chemical methods are an important means of addressing corrosion, scaling, wax buildup, and high pour point / viscosity issues in oil and gas well production. This involves injecting slow-release scale inhibitors, wax removers, and pour point / viscosity depressants to solve these problems. Currently, the most common method is wellhead (surface) dosing, but this requires large dosages, its effectiveness is affected by scaling and wax buildup on large-diameter tools and casing walls, and it is unsuitable for production wells with high casing pressure, high dynamic fluid levels, and high gas-liquid ratios.

[0004] In existing technologies, the main focus has been on addressing the limitations and constraints of wellhead chemical dosing by designing and improving wellbore chemical dosing processes. Typical wellbore chemical dosing methods include solid rod dosing, mechanical drip dosing, electrically controlled drip dosing, annular sealing continuous dosing, and coiled tubing (e.g., hollow sucker rod) dosing.

[0005] Solid rod dosing methods involve shaping the reagent rods into rings or solid bodies, placing them in a steel working cylinder connected between the pump and the perforated pipe, and slowly releasing the reagent through the scouring effect of the produced medium. This method has two main limitations: ① Controlling the reagent dissolution rate is difficult, making precise control of the reagent dosage impossible and affecting the reagent's shelf life; ② After the solidified reagent dissolves in the tailpipe, it easily clogs the oil flow channels.

[0006] Mechanical drip dosing involves connecting the dosing device and the tailpipe below the perforated tube in series. The upper end of the dosing device is sealed, and the lower drip tube, through a unique mechanical design, utilizes the density difference diffusion principle to allow the liquid in the storage tube to continuously flow into the wellbore. This method has two main limitations: ① the flow rate of the reagent is affected by the wellbore pressure and cannot be automatically controlled; ② under high wellbore pressure, the effective period is short.

[0007] Electrically controlled drip dosing methods, such as those described in patent document CN 1021552O5A, involve a drug storage tube connected in series at the top of the dosing control system. The drug enters the system under gravity, and a motor drives a bearing rod and a grinding wheel gate valve to rotate clockwise. During rotation, the grinding wheel gate valve opens, and the chemical agent is quantitatively injected into the wellbore through the flow restriction of the grinding wheel under the rotational force. The limitations of this method are mainly: ① Once the dosing program is set, it cannot be adjusted in real time according to changes in production conditions; ② The effectiveness is affected by factors such as battery life and scaling; ③ The price is relatively high.

[0008] Continuous dosing methods using annular packers, such as patent document CN 106150462A, involve a dosing device connected to the lower part of the tubing string. The chemical is poured from the ground into the annular space between the tubing and casing above the packer. When the liquid column pressure exceeds the pressure in the tubing below the pump, the chemical enters the dosing device, thus achieving dosing. The limitations of this method are mainly: ① It is difficult to control the quantitative dosing; ② The operation process is cumbersome, labor-intensive, and costly; ③ The price is relatively high.

[0009] Continuous tubing dosing, such as patent document CN 107387024A, replaces the conventional solid sucker rod with a hollow sucker rod to achieve continuous dosing of chemicals. The limitations of this method are mainly reflected in: ① increased rod load and system energy consumption; ② poor adaptability to conditions such as high-pour-point oil, sand production, and scaling due to the fixed valve unidirectional flow control design; and ③ relatively high price.

[0010] For example, patent document CN 106761564A connects the dosing tank to the dosing couplings via a dosing pipe, various specialized couplings, and a dosing connection pipe, achieving continuous, non-powered dosing. The limitations of this method are mainly: ① The bottom is not designed for single-flow, making it easy for high-pour-point oil to solidify inside the pipe, affecting the injection effect and stability. ② Non-powered dosing makes quantitative dosing impossible, resulting in low dosing efficiency.

[0011] In summary, existing technologies have enabled quantitative or continuous downhole chemical dosing, but they have not solved the problems of limited (uncontrollable) duration of chemical action, inaccurate control of dosage, and the impact of downhole scaling, sand production, or high crude oil concentration on wellbore chemical dosing operation and effectiveness.

[0012] This invention focuses on oil wells with high casing pressure, high dynamic fluid level, and high gas-liquid ratio, developing a wellbore chemical dosing technology to solve problems such as corrosion, scaling, wax buildup, high pour point, and high viscosity in these wells. This ensures normal oil well production, extends pump inspection cycles, and reduces production costs. To this end, a deep wellbore chemical dosing method and device have been specifically designed to address issues such as poor continuity, quantitative control, and adaptability to well conditions in oil and gas wellbore chemical dosing, improving the accuracy and reliability of wellbore chemical dosing, thereby enhancing the dosing effect. Summary of the Invention

[0013] The purpose of this invention is to solve the problems of limited (uncontrollable) duration of chemical dosing in wellbore, inaccurate control of dosing dosage, and the impact of downhole scaling, sand production, or high crude oil concentration on the operation and effectiveness of wellbore chemical dosing. This invention provides a method and device for deep wellbore chemical dosing.

[0014] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0015] A method and apparatus for deep wellbore chemical delivery, comprising a surface chemical delivery section, a production tubing string, and a downhole chemical delivery section.

[0016] The surface chemical dosing section includes a surface injection skid, surface pipelines, a check valve, and an injection wellhead;

[0017] The production tubing includes tubing, a pump, a screen, and plugs.

[0018] The downhole chemical delivery system includes a delivery-injection tubing, tubing clamps, and an injection-mixer.

[0019] The surface injection skid, surface pipeline, check valve, and injection tubing are connected in sequence. The injection tubing enters from the top of the injection wellhead and exits from the bottom, and is fixed to the outer wall of the tubing by the tubing clamp. The end of the injection tubing is connected to the injection-mixer. The bottom of the injection-mixer is connected to the upper part of the screen pipe, and the bottom of the screen pipe is connected to the plug. The upper part of the injection-mixer is connected to the bottom of the pump, and the upper part of the pump is connected to the tubing. The upper part of the tubing is connected to the injection wellhead, and the injection wellhead bears the entire weight of the production tubing and the downhole chemical injection section.

[0020] The working method of the deep wellbore chemical dosing device is as follows:

[0021] The agent in the surface injection skid, after being pressurized, enters the infusion-injection tubing. When the pressure at the bottom of the agent column in the infusion-injection tubing is greater than the liquid column in the tubing and the opening pressure of the injection-mixer, the agent enters the injection-mixer. Under its diversion-mixing action, it is fully mixed with the liquid flow in the tubing to form a liquid-drug mixture. When the liquid-drug mixture enters the pump, it reaches the wellhead under its lifting action, exerting the agent's effect on the tubing and liquid flow above the injection-mixer.

[0022] Furthermore, the surface chemical dosing section achieves unidirectional fluid flow between itself and the downhole chemical dosing section through the one-way valve. It is equipped with one set of surface pipelines and one-way valves to simultaneously inject chemicals into one well, but not limited to one well.

[0023] Furthermore, in the production tubing, fluid enters the production tubing through the screen tube and plug, filtering solid particles in the wellbore and impurities in the fluid flow, and protecting the injection mixer; the flow area of ​​the screen tube is 2-3 times the cross-sectional area of ​​the tubing, to ensure the oil flow channel and filtration effect.

[0024] Furthermore, in the downhole chemical dosing section, the infusion-injection tubing is welded to the injection-mixer through an injection hole to ensure the sealing of the connection. The injection-mixer is located below the oil pump, and the chemical agent enters the injection-mixer through the infusion-injection tubing to control the unidirectional flow of the chemical agent and ensure thorough mixing with the liquid flow, thereby ensuring the chemical agent takes effect.

[0025] The infusion tubing is either a single continuous injection tube or multiple injection lines connected by threads.

[0026] Furthermore, in the working method of the deep wellbore dosing device, the design depth of the injection-mixer is determined according to the effective action depth of the agent and the working condition action depth, and the higher value of the two is taken;

[0027] The effective depth of the agent is determined based on the effective temperature of the agent measured indoors, and the working condition depth of the agent is determined based on the working condition temperature, wellhead flow temperature, and flow temperature gradient.

[0028] Furthermore, the injection-mixer includes an injection mechanism and a mixing mechanism;

[0029] The injection mechanism includes a socket, a first injection hole, a second injection hole, a mixing body, a mixing template, a pin, a pressure plate, an injection connector, a support rod, and a mixing pressure plate;

[0030] The mixing mechanism includes a first liquid guide plate, a mixing plate, a layer plate, a connecting screw, and a second liquid guide plate;

[0031] One end of the sleeve is threaded to the screen tube, and the other end is threaded to the outer sleeve. The other end of the outer sleeve is connected to the oil pump. Four sets of pin holes are provided at the lower position of the outer sleeve, which are connected to the injection joint and support rod of the injection mechanism through the pins to restrict the axial movement of the injection mechanism. A first injection hole is also provided at the lower position of the outer sleeve, which is concentric with the second injection hole on the injection joint of the injection mechanism and is welded to the infusion tube respectively. The pressure plate and the mixing template are threaded together to the connecting screw of the mixing mechanism to realize the connection of the two mechanisms.

[0032] The other end of the injection connector is threaded to one end of the mixture; the other end of the mixture is stacked parallel to the mixing template and the pressure plate in sequence, and the three are connected by the pin.

[0033] The mixing plate is welded to the plate so that the mixture, mixing template and mixing plate are tightly stacked; the fluid in the screen tube flows through the injection mechanism, passes through the gap between the support rod and the outer tube of the injection joint, the mixture-mixing template-plate-mixing plate and the outer tube-gap in sequence, and enters the mixing mechanism.

[0034] Furthermore, in the injection mechanism, the injection connector has a symmetrical hollow design inside, and the mixture has symmetrically designed channels near the outer wall inside. The drug flows sequentially through the infusion-injection tube and the channel inside the injection head-mixture. The mixing template is compressed and undergoes elastic deformation. The drug is ejected in an annular pattern between the mixing template and the mixture. When the injection stops, the deformation of the mixing template returns to normal, and the channel closes.

[0035] Furthermore, in the mixing mechanism, a mixing unit is formed by two mixing plates, three first liquid guiding plates, and three second liquid guiding plates. The first liquid guiding plates and the second liquid guiding plates are distributed at a horizontal angle of 300° and are welded to the mixing plates.

[0036] The mixing plate has a hollow annular structure, with the hollow interior serving as a channel for liquid flow into the plate.

[0037] Furthermore, the mixing mechanism includes one or more mixing units, wherein the multiple mixing units are welded to the layer plate at 22.5° intervals between adjacent first liquid guide plates, and the layer plate is radially designed with two sets of circular holes of the same size for fluid channels.

[0038] Furthermore, in the mixing mechanism, when the liquid flow enters the next mixing unit from the previous mixing unit, it splits or merges, and this process is repeated to ensure that the medicine is fully mixed.

[0039] The embodiments of the present invention bring the following beneficial effects:

[0040] 1. This invention provides a method for deep wellbore chemical injection, which achieves continuous injection of downhole chemicals through the design of the inlet-outlet chemical tubing and the injection-mixer, solving the problem of chemical injection in wellbore with high casing pressure, high dynamic fluid level and high gas-liquid ratio, and improving the stability and controllability of chemical injection.

[0041] 2. This invention provides a method for designing drug dispensing depth, enabling precise dispensing, improving drug utilization and efficacy, and reducing operating costs.

[0042] 3. The injection-mixer designed in this invention opens and closes the agent channel through the elastic deformation of the mixing template, which can not only ensure the stability of agent injection, but also prevent impurities in the well from entering the infusion-injection pipe under the condition of stopping injection, thus ensuring the long-term high efficiency of the process.

[0043] 4. The injection-mixer designed in this invention further incorporates a mixing mechanism. Through the spaced distribution of multiple mixing units, the liquid flow splits or merges as it enters the next mixing unit from the previous one. This process is repeated to ensure thorough mixing of the drug, improve drug efficacy, and save economic costs.

[0044] 5. This invention enables continuous, quantitative, and controllable drug delivery, thereby improving drug delivery efficiency and efficacy.

[0045] 6. The deep wellbore chemical dosing method provided by this invention is applicable not only to artificial lift wells but also to flowing wells, meeting the needs of the entire life cycle of oil wells, improving the utilization rate of process equipment, and reducing investment costs.

[0046] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of a deep wellbore chemical dosing device provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the injection-mixer structure provided in an embodiment of the present invention.

[0050] Among them, 1-Surface injection skid, 2-Surface pipeline, 3-Check valve, 4-Injection wellhead, 5-Tubing, 6-Injection tubing, 7-Oil pump, 8-Pipe clamp, 9-Injection mixer, 10-Screw pipe, 11-Plug;

[0051] 901-Socket, 902-1-First Injection Hole, 902-2-Second Injection Hole, 903-Mix, 904-Mixing Template, 905-Pin, 906-Pressure Plate, 907-First Liquid Guide Plate, 908-Outer Tube, 909-Injection Connector, 910-Support Rod, 911-Mixing Pressure Plate, 912-Mixing Plate, 913-Layer Plate, 914-Connecting Screw, 915-Second Liquid Guide Plate. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] like Figure 1-2 As shown, Embodiment 1 of the present invention provides a deep wellbore chemical dosing device, including a surface injection skid 1, a surface pipeline 2, a check valve 3, an injection wellhead 4, an oil pipe 5, a delivery-injection pipeline 6, a pumping pump 7, a pipe clamp 8, an injection-mixer 9, a screen pipe 10, and a plug 11.

[0054] The surface injection skid 1, injection tubing 2, check valve 3, and injection wellhead 4 constitute the surface injection section; the tubing 5, pump 7, screen pipe 10, and plug 11 constitute the production tubing string; and the injection tubing 6, clamp 8, and injection-mixer 9 constitute the downhole injection section.

[0055] The surface injection skid 1 is connected in sequence to the surface pipeline 2, the check valve 3, and the injection-dosing tubing 6. The injection-dosing tubing 6 enters from the top of the injection wellhead 4 and exits from the bottom. It is fixed to the outer wall of the tubing 5 by the pipe clamp 8, and its end is connected to the injection-mixer 9. The bottom of the injection-mixer 9 is connected to the upper part of the screen pipe 10, and the bottom of the screen pipe 10 is connected to the plug 11. The upper part of the injection-mixer 9 is connected to the bottom of the pumping pump 7, and the upper part of the pumping pump 7 is connected to the tubing 5. The upper part of the tubing 5 is connected to the injection wellhead 4, and the injection wellhead 4 bears the entire weight of the production tubing and the downhole dosing section.

[0056] In the surface chemical dosing section of this embodiment, the one-way valve 3 enables unidirectional flow of fluid between the surface and downhole chemical dosing sections to protect the surface injection skid; by matching 1-N sets of surface pipelines 2 and one-way valves 3, 1-N wells can be injected simultaneously.

[0057] In the production tubing of this embodiment, by designing the screen pipe 10 and the plug 11, the fluid can only enter the production tubing through the screen pipe 10, effectively filtering solid particles in the wellbore and impurities in the fluid flow, and protecting the injection mixer; the flow area of ​​the screen pipe is designed to be 2-3 times the cross-sectional area of ​​the tubing 5 to ensure sufficient oil flow channels and filtration effect.

[0058] In the downhole chemical dosing section of this embodiment, the infusion-injection tubing 6 is welded to the injection-mixer 9 through the injection hole to ensure the sealing of the connection. The injection-mixer 9 is located below the oil pump. The chemical in the infusion-injection tubing enters the injection-mixer and is fully mixed with the liquid flow to ensure that the chemical can play its full role.

[0059] The infusion tube 6, from the ground to the injection-mixer 9, can be a single continuous injection tube or multiple injection lines connected by threads.

[0060] In this embodiment, the injection-mixer 9 mainly consists of a socket 901, a first injection hole 902-1, a second injection hole 902-2, a mixer 903, a mixing template 904, a pin 905, a pressure plate 906, a first liquid guide plate 907, an outer sleeve 908, an injection connector 909, a support rod 910, a mixing pressure plate 911, a mixing plate 912, a shelf 913, a connecting screw 914, and a second liquid guide plate 915.

[0061] The mixture 903, mixing template 904, pin 905, pressure plate 906, injection connector 909, support rod 910, and mixing pressure plate 911 together form an injection mechanism; the first liquid guide plate 907, mixing plate 912, layer plate 913, connecting screw 914, and second liquid guide plate 915 together form a mixing mechanism.

[0062] One end of the sleeve 901 is threaded to the screen tube 10, and the other end is threaded to the outer sleeve 908. The other end of the outer sleeve 908 is connected to the oil pump 7. Four sets of pin holes are designed at the lower position of the outer sleeve 908. The pins 905 are connected to the support rod 910 of the injection head 909 of the injection mechanism to restrict the axial movement of the injection mechanism. The lower position of the outer sleeve 908 is also provided with a first injection hole 902-1, which is concentric with the second injection hole 902-2 on the injection joint 909 of the injection mechanism and is welded to the infusion-injection tube 6 respectively. The other end of the injection mechanism is a pressure plate 906, which, together with the mixing template 904, is threaded to the connecting screw 914 of the mixing mechanism to realize the connection of the two mechanisms.

[0063] The other end of the injection connector 909 is connected to the mixture 903 by a thread; the other end of the mixture 903 is stacked in parallel with the mixing template 904 and the pressure plate 906 in sequence, and the three are connected by a pin 905; the other end of the mixing pressure plate 911 is welded with the pressure plate 906 so that the mixture 903, the mixing template 904, and the mixing pressure plate 911 are tightly stacked; the fluid in the screen tube flows through the injection mechanism, passes through the gap between the support rod 910 of the injection head 909 and the outer tube 908, and the gap between the mixture 903, the mixing template 904, the pressure plate 906, the mixing pressure plate 911, and the outer tube 908 in sequence, and enters the mixing mechanism.

[0064] In the injection mechanism of this embodiment, the injection connector 909 is designed with four support rods 910 of the same size at 90° intervals. The overall projected diameter is slightly smaller than the inner diameter of the outer tube 908, and the interior is designed with a symmetrical hollow structure.

[0065] In this embodiment, the mixture 903 has symmetrically designed channels near its outer wall. The drug in the infusion tube 6 acts on the mixing template 904 through the injection head 909 and the internal channels of the mixture 903. The mixing template 904 is compressed and undergoes elastic deformation. The drug is sprayed out in an annular pattern between the mixing template 904 and the mixture 903. When the drug injection stops, the deformation of the mixing template 904 returns to normal and the channels close.

[0066] In the mixing mechanism of this embodiment, a mixing unit is formed by two mixing plates, three first liquid guiding plates 907, and three second liquid guiding plates. The three first liquid guiding plates 907 and three second liquid guiding plates 915 are evenly distributed at a horizontal angle of 300° and welded to two mixing plates 912 (upper and lower) to form a mixing unit. The mixing mechanism may include one mixing unit or multiple mixing units. Multiple mixing units are welded to the layer plate 913 at a 22.5° interval between adjacent first liquid guiding plates. When the liquid flows from the previous mixing unit to the next, it splits or merges. This process is repeated to ensure that the agent is fully mixed.

[0067] The mixing plate 912 has a hollow annular structure, with the hollow interior serving as a channel for the liquid to enter the layer plate 913. The layer plate 913 is radially designed with two sets of circular holes of the same size as fluid channels.

[0068] Example 2: This invention provides a method for deep wellbore chemical injection, the specific implementation method of which is as follows:

[0069] The agent in the surface injection skid is pressurized and then enters the infusion tubing, reaching the downhole injection mixer. When the pressure at the bottom of the agent column in the infusion tubing is greater than the liquid column in the tubing plus the opening pressure of the injection mixer, the agent enters the injection mixer. Under its diversion and mixing action, it is fully mixed with the liquid flow in the tubing to maximize the effect of the agent.

[0070] Furthermore, the liquid-pharmaceutical mixture enters the oil pump and, under its lifting action, reaches the wellhead, exerting its chemical effect on the tubing and fluid flow above the injection-mixer.

[0071] The method for deep wellbore chemical injection involves injecting chemicals downhole at a depth determined by the effective depth of the chemicals and the working depth, using the higher of the two values. The calculation formula is as follows:

[0072] H = min(H1, H2).

[0073] The effective depth of the agent is determined based on the effective temperature of the agent measured indoors, and the calculation formula is as follows:

[0074] H1=(T1-Tw) / GradT

[0075] The depth of action of the reagent under operating conditions is determined based on the operating temperature (e.g., the wax precipitation point of crude oil), and its calculation formula is as follows:

[0076] H2=(T2+△T-Tw) / GradT

[0077] The specific meanings of the symbols in the above formula are as follows:

[0078] H—Deep depth of chemical injection in the well, m; H1—Effective depth of chemical action, m; T1—Effective temperature of chemical action, ℃; Tw—Wellhead flow temperature, ℃; GradT—Wellbore flow temperature gradient, ℃; H2—Deep depth of action under operating conditions, m; T2—Operating temperature, ℃; ΔT—Wellbore flow temperature gradient, ℃.

[0079] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0080] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A deep wellbore chemical dosing device, characterized in that, The deep wellbore chemical dosing system includes a surface dosing section, a production tubing string, and a downhole dosing section. The surface chemical dosing section includes a surface injection skid, surface pipelines, a check valve, and an injection wellhead; The production tubing includes tubing, a pump, a screen, and plugs. The downhole chemical delivery system includes a delivery-injection tubing, tubing clamps, and an injection-mixer. The surface injection skid, surface pipeline, check valve, and injection tubing are connected in sequence. The injection tubing enters from the top of the injection wellhead and exits from the bottom, and is fixed to the outer wall of the tubing by the tubing clamp. The end of the injection tubing is connected to the injection-mixer. The bottom of the injection-mixer is connected to the upper part of the screen pipe, and the bottom of the screen pipe is connected to the plug. The upper part of the injection-mixer is connected to the bottom of the pump, and the upper part of the pump is connected to the tubing. The upper part of the tubing is connected to the injection wellhead, and the injection wellhead bears the entire weight of the production tubing and the downhole chemical injection section. The working method of the deep wellbore chemical dosing device is as follows: The agent in the ground injection skid is pressurized and enters the injection tubing. When the pressure at the bottom of the agent column in the injection tubing is greater than the liquid column in the tubing and the opening pressure of the injection-mixer, the agent enters the injection-mixer. Under its diversion-mixing action, it is fully mixed with the liquid flow in the tubing to form a liquid-drug mixture. When the liquid-drug mixture enters the pump, it reaches the wellhead under its lifting action, exerting the agent effect on the tubing and liquid flow above the injection-mixer. The injection-mixer includes an injection mechanism and a mixing mechanism; The injection mechanism includes a socket, a first injection hole, a second injection hole, a mixing body, a mixing template, a pin, a pressure plate, an injection connector, a support rod, and a mixing pressure plate; The mixing mechanism includes a first liquid guide plate, a mixing plate, a layer plate, a connecting screw, and a second liquid guide plate; One end of the sleeve is threaded to the screen tube, and the other end is threaded to the outer sleeve. The other end of the outer sleeve is connected to the oil pump. Four sets of pin holes are provided at the lower position of the outer sleeve, which are connected to the injection joint and support rod of the injection mechanism through the pins to restrict the axial movement of the injection mechanism. A first injection hole is also provided at the lower position of the outer sleeve, which is concentric with the second injection hole on the injection joint of the injection mechanism and is welded to the infusion tube respectively. The pressure plate and the mixing template are threaded together with the connecting screw of the mixing mechanism to realize the connection of the two mechanisms. The other end of the injection connector is threaded to one end of the mixture; the other end of the mixture is stacked parallel to the mixing template and the pressure plate in sequence, and the three are connected by the pin. The mixing plate is welded to the plate so that the mixture, mixing template, and mixing plate are tightly stacked; the fluid in the screen tube flows through the injection mechanism, passes sequentially through the gap between the support rod and the outer tube of the injection joint, the mixture-mixing template-plate-mixing plate and the outer tube-gap, and enters the mixing mechanism; In the injection mechanism, the injection connector has a symmetrical hollow design inside, and the mixture has symmetrically designed channels near the outer wall inside. The drug flows sequentially through the infusion-injection tube and the channel inside the injection head-mixture. The mixing template is compressed and undergoes elastic deformation. The drug is sprayed out in an annular pattern between the mixing template and the mixture. When the injection stops, the deformation of the mixing template returns to normal, and the channel closes.

2. The deep wellbore chemical dosing device according to claim 1, characterized in that, The surface chemical dosing section achieves unidirectional fluid flow between itself and the downhole chemical dosing section through the one-way valve. It is equipped with a set of surface pipelines and one-way valves to simultaneously inject chemicals into one well.

3. The deep wellbore chemical dosing device according to claim 1, characterized in that, In the production tubing, fluid enters the production tubing through the screen tube and plug, filtering solid particles in the wellbore and impurities in the fluid flow, and protecting the injection mixer; the flow area of ​​the screen tube is 2-3 times the cross-sectional area of ​​the tubing, to ensure the oil flow channel and filtration effect.

4. The deep wellbore chemical dosing device according to claim 1, characterized in that, In the downhole chemical dosing section, the infusion-injection tubing is welded to the injection-mixer through an injection hole to ensure the sealing of the connection. The injection-mixer is located below the oil pump. The chemical agent enters the injection-mixer through the infusion-injection tubing to control the unidirectional flow of the chemical agent and ensure thorough mixing with the liquid flow, thereby ensuring the chemical agent takes effect. The infusion tubing is either a single continuous injection tube or multiple injection lines connected by threads.

5. The deep wellbore chemical dosing device according to claim 1, characterized in that, In the working method of the deep wellbore dosing device, the design depth of the injection-mixer is determined according to the effective action depth of the agent and the working condition action depth, and the higher value of the two is taken; The effective depth of the agent is determined based on the effective temperature of the agent measured indoors, and the working condition depth of the agent is determined based on the working condition temperature, wellhead flow temperature, and flow temperature gradient.

6. The deep wellbore chemical dosing device according to claim 1, characterized in that, The mixing mechanism comprises two mixing plates, three first liquid guiding plates, and three second liquid guiding plates forming a mixing unit. The first liquid guiding plates and the second liquid guiding plates are distributed at 300° intervals along the horizontal plane and are welded to the mixing plates. The mixing plate has a hollow annular structure, with the hollow interior serving as a channel for liquid flow into the plate.

7. The deep wellbore chemical dosing device according to claim 1, characterized in that, The mixing mechanism includes one or more mixing units, wherein the multiple mixing units are welded to the layer plate at 22.5° intervals between adjacent first liquid guide plates, and the layer plate is provided with two sets of circular holes of the same size in the radial direction for fluid channels.

8. The deep wellbore chemical dosing device according to claim 7, characterized in that, In the mixing mechanism, when the liquid flows from the previous mixing unit to the next, it splits or merges, and this process is repeated to ensure that the medicine is fully mixed.

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