An oilfield directional water injection tool and method suitable for use in heterogeneous formations

Abstract

This invention relates to the field of resource and environmental technology, and discloses a directional water injection tool and method suitable for heterogeneous oilfield formations, solving the problem of low permeability. It includes a setting module, a sealing module at its lower end, a water injection module at its lower end, and a fixing module at its lower end. The setting module includes an upper connector with an upper outer core tube at its lower end. The sealing module includes several end sleeves, each with a fan-shaped end sleeve at its lower end. The water injection module includes a water injection nozzle with a lower outer core tube fixed to it. The fixing module includes a lower backwash sleeve with a lower connector at its upper end. This tool improves oil recovery. The fan-shaped end sleeves allow control of the water injection direction, increasing formation permeability in a specified direction and further enhancing the displacement of crude oil in different directions within the well network.

Description

Technical Field

[0001] This invention belongs to the field of resource and environmental technology, specifically a tool and method for directional water injection in oilfields with heterogeneous strata. Background Technology

[0002] During water injection in oilfields, as the injection volume increases, the unevenness of the formation water absorption profile intensifies significantly. Considering the heterogeneity and complexity of the formation and oil layers, in high-permeability oil layers, when the injected water volume greatly exceeds the produced fluid, it easily accelerates the water flooding of the oil layer. After the oil layer is flooded over a large area, the water drive efficiency is greatly reduced, turning into a situation of washing oil with water. In medium- and low-permeability layers, due to the difference in permeability between oil reservoir layers, the injected water tends to rush along the oil layer with higher permeability, which can easily cause a sharp increase in water cut, thereby slowing down the oil production rate of a single well and reducing the recovery rate of the block.

[0003] Existing directional water injection tools mostly use full-circumference expansion rubber sleeves as their core sealing components. After the rubber sleeve expands and seals, it fits the inner wall of the casing around the entire circumference without a directional guiding structure, making it impossible to accurately align with the target water injection zone. They also use non-adjustable explosive triggering elements with a fixed conduction pressure threshold. When dealing with formations of different pressure levels, different specifications of explosive elements need to be customized in advance. When changing them on-site, the tool needs to be retrieved, which increases the cost of single-well pressure adaptation and cannot cope with multiple pressure zones in the same well. Existing technologies and equipment can only perform water injection and oil displacement in a 360° direction at the bottom of the well and have poor pressure adaptation flexibility. Therefore, this invention proposes a directional water injection tool and method suitable for heterogeneous formations in oilfields to solve the above problems. Summary of the Invention

[0004] In view of the above situation and to overcome the defects of the prior art, the present invention provides a directional water injection tool and method for oilfields with heterogeneous strata, which effectively solves the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a directional water injection tool for oilfields with heterogeneous formations, comprising a setting module, a sealing module at the lower end of the setting module, a water injection module at the lower end of the sealing module, and a fixing module at the lower end of the water injection module; The setting module includes an upper connector, an upper backwash sleeve at the lower end of the upper connector, an upper well-washing piston at the lower end of the upper backwash sleeve, and an upper outer core tube at the lower end of the upper well-washing piston. The sealing module includes several end tubes, each end tube has a spacer ring at its lower end, each spacer ring has a fan-shaped tube at its bottom, each fan-shaped tube has a spacer ring with a baffle at its lower end, each fan-shaped tube has a 45° window along its axial direction, the inner side of the window is pasted with a polyimide wear-resistant layer, and the edges of the window are rounded. The water injection module includes a water injection nozzle, the water injection nozzle is fixed with a lower outer core tube, and a shatterproof glass is provided in the middle of the water injection nozzle; The fixed module includes a lower backwash sleeve, a lower backwash well sealing ring at the upper end of the lower backwash sleeve, a lower outer core sleeve at the upper end of the lower backwash well sealing ring, a lower connector at the lower end of the lower backwash sleeve, and a lower backwash well piston on the outside of the lower connector.

[0006] Preferably, the upper connector is a stepped cylindrical structure with internal threads. The lower end of the upper connector is fixedly connected to the upper end of the upper backwash sleeve by threads. The lower end of the upper backwash sleeve has several grooves evenly distributed along the circumferential direction. Both the lower end of the upper connector and the upper end of the lower connector are provided with several limiting shear pins.

[0007] Preferably, the inner hole of the upper backwash sleeve is a stepped hole, the lower section of the upper backwash sleeve slides in conjunction with the upper washing piston, and an annular sealing groove is provided on the outer circumferential surface of the upper washing piston, with an upper washing sealing ring embedded inside the annular sealing groove.

[0008] Preferably, the lower end shoulder of the upper washing piston is positioned and fixedly connected to the upper end of the upper outer core tube. An upper outer core sleeve is installed on the outer periphery of the upper outer core tube. The lower end face of the upper part of the upper outer core tube is in contact with the upper end face of the end rubber tube. The inner diameter of the upper outer core tube is interference-fitted with the inner diameter of the spacer ring and clearance-fitted with the inner diameter of the end rubber tube and the fan-shaped rubber tube.

[0009] Preferably, the upper shoulder of the lower well-washing piston is positioned and fixedly connected to the lower end of the lower outer core tube, the lower outer core sleeve is installed outside the lower outer core tube, and a lower end annular sealing groove is opened on the outer circumferential surface of the lower well-washing piston, and a lower well-washing sealing ring is embedded in the lower end annular sealing groove.

[0010] Preferably, the end rubber tube, the spacer ring, the fan-shaped rubber tube, and the spacer ring with baffle can all slide on the outer surfaces of the upper outer core tube and the lower outer core tube. The end rubber tube and the fan-shaped rubber tube are coaxially assembled. The lower end of the end rubber tube abuts against the upper end face of the fan-shaped rubber tube through the spacer ring, and the lower end of the fan-shaped rubber tube abuts against the upper end face of the next end rubber tube through the spacer ring with baffle.

[0011] Preferably, the water inlet nozzle has a stepped through-hole structure, the lower end of the water inlet nozzle is fixed by threads to the radial holes of the upper outer core tube and the lower outer core tube, the upper end of the water inlet nozzle is connected to the window of the fan-shaped rubber tube, and the spacer ring with baffle has an annular flange extending radially.

[0012] Preferably, the upper end of the lower backwash sleeve is threadedly connected to the lower end of the lower outer core tube, the lower end of the lower backwash sleeve is connected to the lower connector through the lower limiting shear pin, and the lower connector is coaxially engaged with the lower washing well piston.

[0013] Preferably, the rupture glass is made of borosilicate glass, and the rupture glass is sealed and embedded in the middle hole of the water inlet with epoxy resin adhesive, and there is no gap between the edge of the rupture glass and the wall of the water inlet hole.

[0014] This invention also provides a method for directional water injection in oilfields with heterogeneous formations, based on the directional water injection tool for oilfields with heterogeneous formations as described above, comprising the following steps: Step 1: Connect the assembled directional water injection tool in series with the tubing string. Based on the depth of the target water injection layer, slowly lower the tool to the preset well section. During the lowering process, each module of the tool remains in its initial assembly state. The limiting shear pins of the setting module are in an uncut and locked state. The upper washing piston and the inner wall of the upper backwash sleeve are relatively stationary. The end rubber sleeve and fan-shaped rubber sleeve of the sealing module are in a contracted state. The burst glass of the water injection module achieves the initial sealing of the water injection module through the sealing effect of epoxy resin. The lower connector of the fixing module is fixed to the lower backwash sleeve by the lower limiting shear pin to ensure the overall stability of the tool structure. During the lowering process, the gravity of the tubing string and the coordinated control of the wellhead lowering equipment are used to ensure that the tool moves smoothly along the casing axis until it reaches the corresponding depth of the target water injection layer. Step 2: After the tool reaches the target water injection formation, a hydraulic load is applied to the tubing string through the wellhead. The hydraulic force is transmitted to the upper washing piston. When the hydraulic pressure reaches the shearing threshold of the limit shear pin, the limit shear pin breaks and unlocks. The upper washing piston slides axially downward along the lower section of the upper reverse washing sleeve. The upper washing sealing ring in its outer circumferential groove fits tightly with the inner hole of the upper reverse washing sleeve. Step 3: At this time, the upper washing piston is positioned by the shoulder and drives the upper outer core tube to move down synchronously. The downward movement of the upper outer core tube pushes the end rubber tube, spacer ring, fan-shaped rubber tube and spacer ring with baffle to slide axially along the outer surface of the upper and lower outer core tubes. After being squeezed, the end rubber tube and fan-shaped rubber tube expand radially and form a tight sealing surface with the inner wall of the casing. The radially extended annular flange of the spacer ring with baffle can limit the radial expansion of the fan-shaped rubber tube to no more than 25%. Several fan-shaped rubber tubes are precisely aligned with the target water injection layer through 45° windows opened in the circumferential direction. During this process, the lower washing piston and the lower connector maintain coaxial cooperation to compensate for the deformation of the sealing elements and ensure the stability of the tool downhole. Step 4: After sealing, water is continuously injected into the tubing string. The water flows through the internal channels of the upper connector and the upper backwash sleeve into the inner cavities of the upper and lower outer core tubes. When the water pressure reaches the preset bursting pressure of the bursting glass in the water injection module, the bursting glass breaks, and the water flows out through the water injection nozzle. Since the upper end of the water injection nozzle is connected to the window of the fan-shaped rubber tube, the water flows precisely into the target formation along the window, realizing directional water injection into heterogeneous formations. During the water injection process, the injection pressure can be adjusted to adapt to the water absorption requirements of different formations. Step 5: When the target formation is saturated with water or reaches the preset total injection volume, stop applying pressure to the tubing string and gradually reduce the pressure in the tubing to atmospheric pressure. At this time, the residual water pressure in the injection nozzle disappears, the formation fluid and the fluid in the tubing reach pressure balance, the fan-shaped rubber sleeve contracts radially and separates from the inner wall of the casing. At the same time, after the hydraulic difference disappears, the upper and lower well washing pistons reset along the inner wall of the corresponding casing, the upper and lower well washing sealing rings return to their initial sealing state, the connection between the water injection channel and the backwash channel is cut off, and the injection cessation and shutdown work is completed. Step Six: After the injection is stopped and shut off, the tubing string is pulled upwards using the wellhead hoisting equipment. The tension of the tubing string is transmitted to the upper connector, which drives the entire tool to move upwards along the casing axis. By continuously pulling the tubing string, the tool is gradually taken out from the well to the surface, completing the entire operation process. After being taken out, the tool can be disassembled and inspected for use in the next operation.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) This tool improves the recovery rate. This tool can control the water injection direction through the fan-shaped rubber sleeve, improve the formation permeability in the specified direction of the oil well, and further improve the crude oil displacement in different directions within the well network of the water injection wells; (2) This tool has strong pressure adaptability. The thickness of the burst glass in the water injection nozzle can be adjusted according to the formation pressure to achieve precise control of different pressure thresholds and flexibly adapt to different pressures. (3) This tool has a simple structure and is easy to operate. The designed directional water injection tool has a simple structure, is easy to operate, has low cost, is universal, and is easy to mass-produce. (4) The radially extending annular flange of the partition ring with baffle can limit the radial expansion of the fan-shaped rubber tube to no more than 25%. The module achieves radial expansion through axial setting pressure. The fan-shaped rubber tube is precisely aligned with the target water injection layer through the directional window to achieve sealing and directional water injection guidance, thus completing the sealing operation of the water injection tool. (5) This tool is precisely aligned with the target water injection layer through the window on the fan-shaped rubber tube, and the water injection nozzle is equipped with replaceable thickness of burst glass to adapt to different formation pressures and ensure initial sealing performance. The outer side of the lower connector is coaxially matched with the bottom washing piston to realize a directional water injection tool for oilfields with a fixed sealing element at one end and a floating sealing element at the other end, which can effectively compensate for the deformation required by the sealing element, protect the end of the sealing element, form the lower end fixed support unit of the tool, and ensure that the tool is stably positioned in the downhole tubing, thereby improving the safety of the skin. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0017] In the attached diagram: Figure 1 This is a schematic diagram illustrating the working principle of this tool; Figure 2 This is a schematic diagram of the overall structure of this tool; Figure 3 This is a schematic diagram of the sealing module of this tool; Figure 4 This is a schematic diagram of the sealing module of this tool; Figure 5 This is a schematic diagram of the water injection module of this tool; Figure 6 This is a schematic diagram of the fixed modules of this tool; Figure 7 This is a schematic diagram of the fan-shaped glue tube of this tool; Figure 8 This is a schematic diagram of the key components of this tool.

[0018] In the diagram: 1-Upper connector; 2-Upper backwash sleeve; 3-Upper well-washing piston; 4-Upper well-washing sealing ring; 5-Upper outer core sleeve; 6-Upper outer core tube; 7-End rubber sleeve; 8-Spacer ring; 9-Fan-shaped rubber sleeve; 10-Spacer ring with baffle; 11-Water injection nozzle; 12-Break glass; 13-Lower outer core tube; 14-Lower outer core sleeve; 15-Lower well-washing sealing ring; 16-Lower backwash sleeve; 17-Lower well-washing piston; 18-Lower connector; 19-Limiting shear pin. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Example 1, by Figures 1-8 The present invention provides a directional water injection tool for oilfields with heterogeneous formations, comprising a setting module, a sealing module at the lower end of the setting module, a water injection module at the lower end of the sealing module, and a fixing module at the lower end of the water injection module; The setting and sealing module includes an upper connector 1, an upper backwash sleeve 2 at the lower end of the upper connector 1, an upper well-washing piston 3 at the lower end of the upper backwash sleeve 2, and an upper outer core tube 6 at the lower end of the upper well-washing piston 3. The sealing module includes several end tubes 7, each end tube 7 is provided with a spacer ring 8 at its lower end, each spacer ring 8 is provided with a fan-shaped tube 9 at its bottom, each fan-shaped tube 9 is provided with a spacer ring with a baffle 10 at its lower end, each fan-shaped tube 9 has a 45° window along the axial direction, the inner side of the window is pasted with a polyimide wear-resistant layer, and the edges of the window are rounded. The water injection module includes a water nozzle 11, the water nozzle 11 is fixed with a lower outer core tube 13, and the water nozzle 11 is provided with a shattering glass 12 in the middle. The fixed module includes a lower backwash sleeve 16, with a lower backwash sealing ring 15 at the upper end of the lower backwash sleeve 16, a lower outer core sleeve 14 at the upper end of the lower backwash sealing ring 15, a lower connector 18 at the lower end of the lower backwash sleeve 16, and a lower backwash piston 17 on the outer side of the lower connector 18.

[0021] Beneficially, the upper connector 1 is a stepped cylindrical structure with internal threads. The lower end of the upper connector 1 is fixedly connected to the upper end of the upper backwash sleeve 2 via threads. The lower end of the upper backwash sleeve 2 has several grooves evenly distributed along the circumference. Both the lower end of the upper connector 1 and the upper end of the lower connector 18 are provided with several limiting shear pins 19. The inner hole of the upper backwash sleeve 2 is a stepped hole. The lower section of the upper backwash sleeve 2 slides with the upper washing piston 3. An annular sealing groove is formed on the outer circumference of the plug 3. An upper well-washing sealing ring 4 is embedded inside the annular sealing groove. The lower end shoulder of the upper well-washing piston 3 is positioned and fixedly connected to the upper end of the upper outer core tube 6. An upper outer core sleeve 5 is installed on the outer circumference of the upper outer core tube 6. The lower end face of the upper part of the upper outer core tube 6 is in contact with the upper end face of the end rubber tube 7. The inner diameter of the upper outer core tube 6 is interference-fitted with the inner diameter of the spacer ring 8, and clearance-fitted with the inner diameter of the end rubber tube 7 and the fan-shaped rubber tube 9. When using this tool, the operator connects the assembled directional water injection tool in series via tubing. Based on the depth of the target water injection layer, the tool is slowly lowered to the predetermined well section. During the lowering process, all modules of the tool remain in their initial assembled state. The limiting shear pin 19 of the setting module is in an unsheathed locked state. The upper washing piston 3 is relatively stationary with respect to the inner wall of the upper backwash sleeve 2. The end rubber sleeve 7 and the fan-shaped rubber sleeve 9 of the sealing module are in a contracted state. The bursting glass 12 of the water injection module, through the sealing effect of the epoxy resin adhesive, achieves the sealing of the water injection module. Initially sealed, the lower connector 18 of the fixed module and the lower backwash sleeve 16 are fixed by the lower limiting shear pin 19 to ensure the overall stability of the tool structure. During the lowering process, the gravity of the tubing string and the coordinated control of the wellhead lowering equipment are used to ensure that the tool moves smoothly along the casing axis until it reaches the corresponding depth of the target water injection layer. After the tool reaches the target water injection formation, a hydraulic load is applied to the tubing string through the wellhead. The hydraulic force is transmitted to the upper washing piston 3. When the hydraulic pressure reaches the shear threshold of the limiting shear pin 19, the limiting shear pin 19 breaks. Locked, the upper washing piston 3 slides axially downward along the lower hole section of the upper backwash sleeve 2, and the upper washing sealing ring 4 in its outer peripheral groove is tightly fitted with the inner hole of the upper backwash sleeve 2. After sealing, water is continuously injected into the tubing string. The water flows through the upper connector 1 and the internal channel of the upper backwash sleeve 2 into the inner cavity of the upper outer core tube 6 and the lower outer core tube 13. When the water pressure reaches the preset bursting pressure of the bursting glass 12 in the water injection module, the bursting glass 12 breaks, and the water flows out through the water injection nozzle 11. Due to the water injection... The upper end of the water nozzle 11 is connected to the window of the fan-shaped rubber sleeve 9. The water flows precisely into the target formation along the window, realizing directional water injection into heterogeneous formations. During the water injection process, the injection pressure can be adjusted to adapt to the water absorption requirements of different formations. After the injection is stopped and closed, the tubing string is pulled upward by the wellhead hoisting equipment. The tension of the tubing string is transmitted to the upper connector 1, which drives the tool to move upward along the casing axis. By continuously pulling the tubing string, the tool is gradually taken out from the well to the surface, completing the entire operation process. After being taken out, the tool can be disassembled and repaired for use in the next operation.

[0022] Beneficially, the end sleeve 7, the spacer ring 8, the fan-shaped sleeve 9, and the spacer ring with baffle 10 can all slide on the outer surfaces of the upper outer core tube 6 and the lower outer core tube 13. The end sleeve 7 and the fan-shaped sleeve 9 are coaxially assembled. The lower end of the end sleeve 7 abuts against the upper end face of the fan-shaped sleeve 9 through the spacer ring 8. The lower end of the fan-shaped sleeve 9 abuts against the upper end face of the next end sleeve 7 through the spacer ring with baffle 10. The water nozzle 11 has a stepped through-hole structure. The lower end of the water nozzle 11 is fixed to the radial hole of the upper outer core tube 6 and the lower outer core tube 13 by threads. The upper end of the water nozzle 11 is in communication with the window of the fan-shaped sleeve 9. The spacer ring with baffle 10 has an annular flange extending radially. The shatterproof glass 12 is made of boron. Made of silica glass, the rupture glass 12 is sealed and embedded in the middle hole of the water inlet 11 with epoxy resin. There is no gap between the edge of the rupture glass 12 and the hole wall of the water inlet 11. The upper shoulder of the lower washing piston 17 is positioned and fixedly connected to the lower end of the lower outer core tube 13. The lower outer core sleeve 14 is installed outside the lower outer core tube 13. The lower washing piston 17 has a lower annular sealing groove on its outer circumference. A lower washing sealing ring 15 is embedded in the lower annular sealing groove. The upper end of the lower backwash sleeve 16 is threaded to the lower end of the lower outer core tube 13. The lower end of the lower backwash sleeve 16 is connected to the lower connector 18 through the lower limiting shear pin 19. The lower connector 18 is coaxially engaged with the lower washing piston 17. Furthermore, the upper washing piston 3, positioned by a shoulder, drives the upper outer core tube 6 to move downwards synchronously. The downward movement of the upper outer core tube 6 pushes the end rubber sleeve 7, the spacer ring 8, the fan-shaped rubber sleeve 9, and the spacer ring with baffle 10 to slide axially along the outer surfaces of the upper outer core tube 6 and the lower outer core tube 13. After being compressed, the end rubber sleeve 7 and the fan-shaped rubber sleeve 9 expand radially, forming a tightly fitting sealing surface with the inner wall of the casing. The radially extending annular flange of the spacer ring with baffle 10 can limit the radial expansion of the fan-shaped rubber sleeve 9 to no more than 25%. Several fan-shaped rubber sleeves 9 are precisely aligned with the target water injection layer through 45° windows opened circumferentially. During this process, the lower washing piston 17 and the... The lower connector 18 maintains a coaxial fit to compensate for the deformation of the sealing element and ensure the stability of the tool downhole. When the target formation is saturated with water or reaches the preset total injection volume, the pressure applied to the tubing string is stopped, and the pressure inside the tubing is gradually reduced to atmospheric pressure. At this time, the residual water pressure in the water injection nozzle 11 disappears, and the formation fluid and the fluid inside the tubing form a pressure balance. The fan-shaped rubber sleeve 9 contracts radially and separates from the inner wall of the casing. At the same time, after the hydraulic difference disappears, the upper washing piston 3 and the lower washing piston 17 reset along the corresponding inner wall of the casing. The upper washing sealing ring 4 and the lower washing sealing ring 15 return to their initial sealing state, cutting off the connection between the water injection channel and the backwash channel, and completing the shutdown operation.

[0023] This embodiment provides a method for directional water injection in oilfields with heterogeneous formations, based on the aforementioned directional water injection tool for oilfields with heterogeneous formations, and includes the following steps: Step 1: Connect the assembled directional water injection tool in series with the tubing string. Based on the depth of the target water injection layer, slowly lower the tool to the preset well section downhole. During the lowering process, each module of the tool remains in its initial assembly state. The limiting shear pin 19 of the setting module is in an uncut and locked state. The upper washing piston 3 and the inner wall of the upper backwash sleeve 2 are relatively stationary. The end rubber sleeve 7 and the fan-shaped rubber sleeve 9 of the sealing module are in a contracted state. The burst glass 12 of the water injection module achieves the initial sealing of the water injection module by means of the sealing effect of epoxy resin. The lower connector 18 of the fixing module and the lower backwash sleeve 16 are fixed by the lower limiting shear pin 19 to ensure the overall stability of the tool structure. During the lowering process, the gravity of the tubing string and the coordinated control of the wellhead lowering equipment are used to ensure that the tool moves smoothly along the casing axis until it reaches the corresponding depth of the target water injection layer. Step 2: After the tool reaches the target water injection formation, a hydraulic load is applied to the tubing string through the wellhead. The hydraulic force is transmitted to the upper washing piston 3. When the hydraulic pressure reaches the shear threshold of the limit shear pin 19, the limit shear pin 19 breaks and unlocks. The upper washing piston 3 slides axially downward along the lower hole section of the upper backwash sleeve 2. The upper washing sealing ring 4 in its outer peripheral groove fits tightly with the inner hole of the upper backwash sleeve 2. Step 3: At this time, the upper washing piston 3 drives the upper outer core tube 6 to move down synchronously through the shoulder positioning. The downward movement of the upper outer core tube 6 pushes the end rubber tube 7, the spacer ring 8, the fan-shaped rubber tube 9 and the spacer ring with baffle 10 to slide axially along the outer surface of the upper outer core tube 6 and the lower outer core tube 13. After being squeezed, the end rubber tube 7 and the fan-shaped rubber tube 9 expand radially and form a tightly fitting sealing surface with the inner wall of the casing. The radially extended annular flange of the spacer ring with baffle 10 can limit the radial expansion of the fan-shaped rubber tube 9 to no more than 25%. Several fan-shaped rubber tubes 9 are precisely aligned with the target water injection layer through the 45° window opened in the circumferential direction. During this process, the lower washing piston 17 and the lower connector 18 maintain coaxial cooperation to compensate for the deformation of the sealing element and ensure the stability of the tool downhole. Step 4: After sealing, water is continuously injected into the tubing column. The water flows through the internal channels of the upper connector 1 and the upper backwash sleeve 2 into the inner cavity of the upper outer core tube 6 and the lower outer core tube 13. When the water pressure reaches the preset bursting pressure of the bursting glass 12 in the water injection module, the bursting glass 12 breaks, and the water flows out through the water injection nozzle 11. Since the upper end of the water injection nozzle 11 is connected to the window of the fan-shaped rubber tube 9, the water flows precisely into the target formation along the window, realizing directional water injection into heterogeneous formations. During the water injection process, the injection pressure can be adjusted to adapt to the water absorption requirements of different formations. Step 5: When the target formation is saturated with water or reaches the preset total injection volume, stop applying pressure to the tubing string and gradually reduce the pressure in the tubing to normal pressure. At this time, the residual water pressure in the water injection nozzle 11 disappears, the formation fluid and the fluid in the tubing reach pressure balance, the fan-shaped rubber sleeve 9 contracts radially and separates from the inner wall of the casing. At the same time, after the hydraulic pressure difference disappears, the upper washing piston 3 and the lower washing piston 17 reset along the inner wall of the corresponding casing. The upper washing sealing ring 4 and the lower washing sealing ring 15 return to their initial sealing state, cutting off the connection between the water injection channel and the backwash channel, and completing the injection cessation and shutdown operation. Step Six: After the injection is stopped and shut off, the tubing string is pulled upwards using the wellhead hoisting equipment. The tension of the tubing string is transmitted to the upper connector 1, which drives the entire tool to move upwards along the casing axis. By continuously pulling the tubing string, the tool is gradually taken out from the well to the surface, completing the entire operation process. After being taken out, the tool can be disassembled and repaired for use in the next operation.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, 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.

[0025] 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 directional water injection tool for oilfields in heterogeneous formations, characterized in that: It includes a setting and sealing module, a sealing module at the lower end of the setting and sealing module, a water injection module at the lower end of the sealing module, and a fixing module at the lower end of the water injection module; The setting module includes an upper connector (1), an upper backwash sleeve (2) at the lower end of the upper connector (1), an upper well-washing piston (3) at the lower end of the upper backwash sleeve (2), and an upper outer core tube (6) at the lower end of the upper well-washing piston (3). The sealing module includes several end tubes (7), each end tube (7) is provided with a spacer ring (8) at its lower end, each spacer ring (8) is provided with a fan-shaped tube (9) at its bottom, each fan-shaped tube (9) is provided with a spacer ring with a baffle (10) at its lower end, each fan-shaped tube (9) has a 45° window along the axial direction, the inner side of the window is pasted with a polyimide wear-resistant layer, and the edges of the window are rounded. The water injection module includes a water injection nozzle (11), the water injection nozzle (11) is fixed with a lower outer core tube (13), and the water injection nozzle (11) is provided with a shatterproof glass (12) in the middle. The fixed module includes a lower backwash sleeve (16), the upper end of which is provided with a lower washing well sealing ring (15), the upper end of which is provided with a lower outer core sleeve (14), the lower end of which is provided with a lower connector (18), and the lower connector (18) is provided with a lower washing well piston (17) on the outside.

2. The directional water injection tool for oilfields in heterogeneous formations according to claim 1, characterized in that: The upper connector (1) is a stepped cylindrical structure with internal threads. The lower end of the upper connector (1) is fixedly connected to the upper end of the upper backwash sleeve (2) by threads. The lower end of the upper backwash sleeve (2) has several grooves evenly distributed along the circumferential direction. The lower end of the upper connector (1) and the upper end of the lower connector (18) are provided with several limiting shear pins (19).

3. The directional water injection tool for oilfields in heterogeneous formations according to claim 2, characterized in that: The inner hole of the upper backwash sleeve (2) is a stepped hole. The lower hole section of the upper backwash sleeve (2) is slidably engaged with the upper washing piston (3). An annular sealing groove is provided on the outer circumferential surface of the upper washing piston (3). An upper washing sealing ring (4) is embedded inside the annular sealing groove.

4. The directional water injection tool for oilfields in heterogeneous formations according to claim 3, characterized in that: The lower end shoulder of the upper washing piston (3) is fixedly connected to the upper end of the upper outer core tube (6). An upper outer core sleeve (5) is installed on the outer periphery of the upper outer core tube (6). The lower end face of the upper part of the upper outer core tube (6) is in contact with the upper end face of the end rubber tube (7). The inner diameter of the upper outer core tube (6) is interference-fitted with the inner diameter of the spacer ring (8), and clearance-fitted with the inner diameter of the end rubber tube (7) and the fan-shaped rubber tube (9).

5. A directional water injection tool for oilfields in heterogeneous formations according to claim 4, characterized in that: The upper shoulder of the lower washing piston (17) is fixedly connected to the lower end of the lower outer core tube (13). The lower outer core sleeve (14) is installed outside the lower outer core tube (13). The lower end annular sealing groove is opened on the outer circumferential surface of the lower washing piston (17). The lower end annular sealing ring (15) is embedded in the lower end annular sealing groove.

6. A directional water injection tool for oilfields in heterogeneous formations according to claim 5, characterized in that: The end rubber tube (7), the spacer ring (8), the fan-shaped rubber tube (9), and the spacer ring with baffle (10) can all slide on the outer surfaces of the upper outer core tube (6) and the lower outer core tube (13). The end rubber tube (7) and the fan-shaped rubber tube (9) are coaxially assembled. The lower end of the end rubber tube (7) abuts against the upper end face of the fan-shaped rubber tube (9) through the spacer ring (8). The lower end of the fan-shaped rubber tube (9) abuts against the upper end face of the next end rubber tube (7) through the spacer ring with baffle (10).

7. A directional water injection tool for oilfields in heterogeneous formations according to claim 6, characterized in that: The water inlet nozzle (11) has a stepped through hole structure. The lower end of the water inlet nozzle (11) is fixed to the radial hole of the upper outer core tube (6) and the lower outer core tube (13) by thread. The upper end of the water inlet nozzle (11) is connected to the window of the fan-shaped rubber tube (9). The spacer ring with baffle (10) has an annular flange extending radially.

8. A directional water injection tool for oilfields in heterogeneous formations according to claim 7, characterized in that: The upper end of the lower backwash sleeve (16) is connected to the lower end of the lower outer core tube (13) by a thread. The lower end of the lower backwash sleeve (16) is connected to the lower connector (18) by the lower end limit shear pin (19). The lower connector (18) is coaxially engaged with the lower washing piston (17).

9. A directional water injection tool for oilfields in heterogeneous formations according to claim 8, characterized in that: The shattering glass (12) is made of borosilicate glass. The shattering glass (12) is sealed and embedded in the middle hole of the water inlet nozzle (11) with epoxy resin. There is no gap between the edge of the shattering glass (12) and the hole wall of the water inlet nozzle (11).

10. A method for directional water injection in oilfields with heterogeneous formations, based on the directional water injection tool for oilfields with heterogeneous formations as described in claim 9, characterized in that: Includes the following steps: Step 1: Connect the assembled directional water injection tool through the tubing string. According to the depth of the target water injection layer, slowly lower the tool to the preset well section downhole. During the lowering process, each module of the tool maintains its initial assembly state. The limiting shear pin (19) of the setting module is in an uncut and locked state. The upper washing piston (3) and the inner wall of the upper backwash sleeve (2) are relatively stationary. The end rubber sleeve (7) and the fan-shaped rubber sleeve (9) of the sealing module are in a contracted state. The burst glass (12) of the water injection module achieves the initial sealing of the water injection module by means of the sealing effect of the epoxy resin. The lower connector (18) of the fixing module and the lower backwash sleeve (16) are fixed by the lower limiting shear pin (19) to ensure the stability of the overall structure of the tool. During the lowering process, the gravity of the tubing string and the coordinated control of the wellhead lowering equipment are used to ensure that the tool moves smoothly along the casing axis until it reaches the corresponding depth of the target water injection layer. Step 2: After the tool reaches the target water injection formation, a hydraulic load is applied to the tubing string through the wellhead. The hydraulic force is transmitted to the upper washing piston (3). When the hydraulic pressure reaches the shear threshold of the limit shear pin (19), the limit shear pin (19) breaks and unlocks. The upper washing piston (3) slides axially downward along the lower hole section of the upper backwash sleeve (2). The upper washing sealing ring (4) in its outer peripheral groove fits tightly with the inner hole of the upper backwash sleeve (2). Step 3: At this time, the upper washing piston (3) drives the upper outer core tube (6) to move down synchronously through the shoulder positioning. The downward movement of the upper outer core tube (6) pushes the end rubber tube (7), the diaphragm ring (8), the fan-shaped rubber tube (9) and the diaphragm ring with baffle (10) to slide axially along the outer surface of the upper outer core tube (6) and the lower outer core tube (13). After being squeezed, the end rubber tube (7) and the fan-shaped rubber tube (9) expand radially and form a tightly fitting sealing surface with the inner wall of the casing. The radially extended annular flange of the diaphragm ring with baffle (10) can limit the radial expansion of the fan-shaped rubber tube (9) to no more than 25%. Several fan-shaped rubber tubes (9) are precisely aligned with the target water injection layer through the 45° window opened in the circumferential direction. During this process, the lower washing piston (17) and the lower connector (18) maintain coaxial cooperation to compensate for the deformation of the sealing element and ensure the stability of the tool downhole. Step 4: After sealing, water is continuously injected into the tubing column. The water flows through the internal channels of the upper connector (1) and the upper backwash sleeve (2) into the inner cavity of the upper outer core tube (6) and the lower outer core tube (13). When the water pressure reaches the preset bursting pressure of the bursting glass (12) in the water injection module, the bursting glass (12) breaks and the water flows out through the water injection nozzle (11). Since the upper end of the water injection nozzle (11) is connected to the window of the fan-shaped rubber tube (9), the water flows precisely into the target formation along the window, realizing directional water injection of heterogeneous formations. During the water injection process, the injection pressure can be adjusted to adapt to the water absorption requirements of different formations. Step 5: When the target formation is saturated with water or reaches the preset total injection volume, stop applying pressure to the tubing string and gradually reduce the pressure in the tubing to normal pressure. At this time, the residual water pressure in the water injection nozzle (11) disappears, the formation fluid and the fluid in the tubing form a pressure balance, the fan-shaped rubber sleeve (9) contracts radially and separates from the inner wall of the casing. At the same time, after the hydraulic difference disappears, the upper washing piston (3) and the lower washing piston (17) reset along the inner wall of the corresponding casing. The upper washing sealing ring (4) and the lower washing sealing ring (15) return to the initial sealing state, cut off the connection between the water injection channel and the backwash channel, and complete the shutdown operation. Step 6: After the injection is stopped and closed, the tubing string is pulled up by the wellhead hoisting equipment. The tension of the tubing string is transmitted to the upper connector (1), which drives the tool to move up along the casing axis. By continuously pulling the tubing string, the tool is gradually taken out from the well to the surface, completing the entire operation process. After taking it out, the tool can be disassembled and repaired for use in the next operation.

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