An integrated intelligent water injection tubing string for offshore oilfields and its installation and construction methods.

Abstract

This invention discloses an integrated intelligent water injection string for offshore oilfields, along with its installation and construction methods. Belonging to the field of oilfield development technology, the string comprises, from top to bottom, a tubing hanger, an upper tubing, a first tubing, a second tubing, and a check valve. The tubing hanger is installed at the upper end of the upper tubing. A first cable-connected backwashing interlayer sealing tool is installed between the upper tubing and the first tubing. Intelligent water injection tools are installed on both the first and second tubing. A second cable-connected backwashing interlayer sealing tool is installed between the first and second tubing. When water is injected into the well through the annulus between the casing and the water injection string, the fluid can pass through the first and second cable-connected backwashing interlayer sealing tools layer by layer, and then enter the water injection string through the check valve for backwashing. The invention also includes installation and construction methods. This invention enables reverse well washing and fine-scale injection in water injection wells, reducing the risk of wellbore blockage and scaling.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development technology, and particularly relates to an integrated intelligent water injection string for offshore oilfields and its installation and construction methods. Background Technology

[0002] Water injection, as a crucial technology for ensuring long-term high and stable oil production, is widely used in both onshore and offshore oilfields in China. To guarantee wellbore safety and extend the service life of process tubing in offshore oilfields, corresponding well-washing processes are necessary. Currently, offshore oilfield water injection primarily employs cable-controlled intelligent water injection, enabling real-time monitoring of downhole parameters and online allocation of stratified water injection volumes. However, it lacks reliable supporting well-washing processes, and reverse washing carries the risk of inter-layer cross-contamination. Therefore, it is essential to improve current supporting well-washing measures. Summary of the Invention

[0003] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide an integrated intelligent water injection string for offshore oil fields.

[0004] The second objective of this invention is to propose an installation method for an integrated intelligent water injection tubing string in offshore oil fields.

[0005] The third objective of this invention is to propose a construction method for an integrated intelligent water injection tubing system for offshore oil fields.

[0006] To achieve the above objectives, the present invention provides an integrated intelligent water injection string for offshore oilfields, comprising a water injection string disposed inside the casing. The water injection string, from top to bottom, includes a tubing hanger, an upper tubing, a first tubing, a second tubing, and a check valve. The tubing hanger is located at the upper end of the upper tubing, corresponding to the upper part of the downhole sand control section. The first and second tubings correspond to the first and second layers of the sand control layer, respectively. A first cable-connected backwashable interlayer sealing tool is provided between the upper tubing and the first tubing, and a second cable-connected backwashable interlayer sealing tool is provided between the first and second tubings. The second cable-through backwashable interlayer packer is provided with a lower end packer on its lower side, and a check valve is provided at the lower end of the second tubing. The first cable-through backwashable interlayer packer is provided with a first packer and a cable-through backwashable positioning seal that cooperates with the first packer. The second cable-through backwashable interlayer packer is provided with a second packer and a cable-through backwashable insertion seal that cooperates with the second packer. The outer surfaces of the first packer and the second packer are both fitted to the inner surface of the casing. The first cable-through backwashable interlayer packer and the second cable-through backwashable interlayer packer are used to achieve water injection interlayer isolation and water injection well backwashing.

[0007] When water is injected into the well through the annulus between the casing and the injection string, the fluid can pass through the first cable-through backwashable interlayer sealing tool and the second cable-through backwashable interlayer sealing tool layer by layer, and then enter the injection string through the single-flow valve for backwashing.

[0008] As a further improvement of the present invention, both the cable-through reversible positioning seal and the cable-through reversible insertion seal include a cable-through reversible sealing body, the cable-through reversible sealing body comprising:

[0009] The tube body has a central flow channel that runs vertically through its middle section. The side wall of the tube body has a cable passage channel that runs vertically through it. The outer wall of the tube body is a stepped surface. The stepped surface includes a first stepped surface, a second stepped surface, and a third stepped surface with decreasing diameters from top to bottom. The side wall of the tube body has a first through hole that connects the outer upper part of the third stepped surface and the central flow channel.

[0010] The backwash inlet outer cylinder is screwed to the second step surface. The backwash inlet outer cylinder is provided with a backwash inlet corresponding to the position of the third step surface. An inner step surface is provided on the lower side of the backwash inlet on the backwash inlet outer cylinder.

[0011] The backwash inlet piston is slidably sleeved between the upper side of the third step surface and the backwash inlet outer cylinder. When the backwash inlet piston moves down and abuts against the inner step surface, the backwash inlet piston can close the backwash inlet.

[0012] The upper end of the backwash channel outer cylinder is screwed to the lower end of the backwash inlet outer cylinder;

[0013] The upper end of the backwash outlet outer cylinder is screwed to the lower end of the backwash channel outer cylinder, and the backwash outlet outer cylinder is provided with a backwash outlet corresponding to the position of the third step surface.

[0014] The connector is screwed to the lower end of the backwash outlet outer cylinder and sleeved on the lower end of the pipe body;

[0015] The backwash channel outer cylinder and the pipe body form a backwash channel that can connect the backwash inlet and the backwash outlet;

[0016] The outer wall of the cable-through backwashable positioning seal tube is provided with a positioning step, the outer diameter of which is larger than the inner diameter of the first packer; the outer diameter of the cable-through backwashable insertion seal tube is smaller than the inner diameter of the first packer.

[0017] As a further improvement of the present invention, the side wall of the tube body is provided with a second through hole, the second through hole connecting the outer side of the lower end of the third step surface and the central flow channel;

[0018] The cable-washable sealing body also includes:

[0019] The backwash outlet piston is slidably sleeved between the backwash outlet outer cylinder, the inner wall of the upper side of the connector, and the tube body. The lower outer side of the backwash outlet piston is provided with a first locking tooth, and the lower side of the backwash outlet piston is provided with a fastening pin hole. The tube body is provided with a corresponding fastening pin groove. The backwash outlet piston is fixed to the lower side of the tube body by fastening pins installed in the fastening pin hole and the fastening pin groove.

[0020] The retaining ring adopts an open C-shaped structure. The inner wall of the retaining ring is provided with a second retaining tooth that engages with the first retaining tooth. The second retaining tooth can guide the first retaining tooth to move upward and prevent the first retaining tooth from moving downward.

[0021] As a further improvement of the present invention, a first intelligent water injection tool is provided on the first tubing, and a second intelligent water injection tool is provided on the second tubing. The first tubing includes a first section, the upper end of which is screwed to the lower end of the first cable-connected backwashable interlayer sealing tool, and the lower end of which is screwed to the upper end of the first intelligent water injection tool. The first intelligent water injection tool includes: an upper connector; a sealing ring, the upper end of which is screwed to the lower end of the upper connector; an outer tube, the upper end of which is screwed to the lower end of the sealing ring, the outer tube having an integrated control board, a pressure testing sub, a control motor, and a water nozzle adjustment module inside; a lower connector, the upper end of which is screwed to the lower end of the outer tube, the lower connector having a water outlet sub, the water outlet sub having an injection nozzle, and a differential pressure flow meter inside the water outlet sub; both the upper connector and the lower connector have cable connectors; the second intelligent water injection tool is connected to the first intelligent water injection tool via a cable, and the first intelligent water injection tool is connected to the wellhead surface equipment via a cable.

[0022] As a further improvement of the present invention, the first oil pipe is further provided with a cable protection coupling. The first oil pipe includes a second section and a third section. The upper end of the second section is screwed to the lower end of the first intelligent water injection tool, and the lower end of the second section is screwed to the upper end of the cable protection coupling. The upper end of the third section is screwed to the lower end of the cable protection coupling, and the lower end of the third section is screwed to the upper end of the second cable-through backwashable interlayer sealing tool. The cable protection coupling includes:

[0023] The central tube has a cable protection channel running through its outer wall. It consists of a first tube section and a second tube section from top to bottom. The diameter of the first tube section is smaller than the diameter of the second tube section. An anti-rotation groove is provided on the lower end side of the first tube section, and an anti-rotation screw is screwed into the anti-rotation groove.

[0024] A pressure ring is screwed to the lower end of the first tube. The side wall of the pressure ring is provided with a cable clamp that passes through along its axis and several limiting holes. The limiting holes facilitate the screwing of the anti-rotation screw.

[0025] As a further improvement of the present invention, the anti-rotation groove includes an outer portion and an inner portion, the diameter of the outer portion is larger than the diameter of the inner portion, the outer portion is used to screw on the anti-rotation screw, and the inner portion is used to accommodate the preload spring. When the anti-rotation screw is screwed on the outer portion, the preload spring is pressed against the inner portion.

[0026] To achieve the above objectives, a second aspect of the present invention provides a method for installing an integrated intelligent water injection string for offshore oilfields as described in any of the above technical solutions, comprising:

[0027] The first packer, the second packer, and the lower packer are installed inside the casing, with the first packer positioned above the sand-proof section, the second packer corresponding to the area between the first and second sections of the sand-proof layer, and the lower packer corresponding to the area between the second and lower sections of the sand-proof layer.

[0028] The water injection tubing is lowered into the well so that the cable-through backwashable positioning seal of the water injection tubing is fitted to the first packer, and the cable-through backwashable insertion seal is fitted to the second packer.

[0029] As a further improvement of the present invention, before the water injection tubing is inserted into the casing, it includes:

[0030] Install the cable protection coupling onto the first oil pipe;

[0031] The preload spring is placed inside the anti-rotation groove of the central tube, and the anti-rotation screw is screwed onto the outside of the anti-rotation groove and the preload spring is pressed.

[0032] Screw the pressure ring onto the lower end of the first tube, tighten the pressure ring, and then reverse the tightening by half a turn. ， Rotate the pressure ring to align the cable-passable slot of the pressure ring with a cable protection channel of the central tube;

[0033] Press the cable down to the bottom of the cable protection channel, rotate the pressure ring, and align one of the limiting holes with the anti-rotation groove;

[0034] Rotate the anti-rotation screw in the opposite direction to rotate it into the limiting groove of the pressure ring.

[0035] To achieve the above objectives, a third aspect of the present invention provides a construction method for an integrated intelligent water injection string for offshore oilfields, applicable to the integrated intelligent water injection string for offshore oilfields as described in any of the above technical solutions, comprising:

[0036] Water is injected into the well from the ground through the gap between the water injection string and the casing annulus. The fluid pushes the backwash inlet piston, which is backwashable and positioned by the cable, upward through the backwash inlet, connecting the backwash inlet, backwash channel and backwash outlet. The fluid flows into the first layer and cleans the blockage between the water injection string and the sand screen blind pipe corresponding to the first layer.

[0037] Fluid pushes the piston of the backwash inlet, which can be inserted into the cable and is sealed, to move upward, connecting the backwash inlet, backwash channel and backwash outlet. Fluid mixed with some blockages flows into the second layer, cleaning the blockages between the water injection pipe and the sand screen blind pipe corresponding to the second layer.

[0038] The fluid containing a large amount of blockage eventually enters the water injection string through the one-way valve at the bottom of the water injection string, and backwashes out the blockage in the wellbore through the central wellhead.

[0039] As a further improvement of the present invention, the fluid mixed with a large amount of blockage material eventually enters the interior of the water injection string through the one-way valve at the bottom of the water injection string. After backwashing out the blockage material in the wellbore through the wellhead of the central string, the method further includes:

[0040] The water is pressurized into the injection string at the wellhead until the fluid passes through the second through hole and pushes the fastener of the backwash outlet piston of the cable-connected backwashable positioning seal and the cable-connected backwashable insertion seal to break. The backwash outlet piston moves upward, and the second tooth of the retaining ring engages with the first tooth of the backwash outlet piston to limit the backwash outlet piston. The backwash channels of the cable-connected backwashable positioning seal and the cable-connected backwashable insertion seal are completely closed.

[0041] This invention provides an integrated intelligent water injection tubing string and installation method for offshore oilfields, as well as a construction method, which has at least the following beneficial effects:

[0042] 1. A first cable-through backwashing interlayer sealing tool is provided between the upper tubing and the first tubing, and a second cable-through backwashing interlayer sealing tool is provided between the first tubing and the second tubing. It can realize reverse well washing of intelligent water injection well by annular water injection. When well washing is not required, the well washing channel can be closed by injecting fluid of appropriate pressure into the water injection string to avoid interlayer cross-flow caused by backwashing channel.

[0043] 2. The first oil pipe is equipped with a cable protection coupling, so that the cable can be protected in the corresponding sand-proof section without stripping the outer sheath of the steel pipe cable when the water injection pipe string is lowered.

[0044] 3. The first tubing is equipped with a first intelligent water injection tool, and the second tubing is equipped with the same second intelligent water injection tool. They are connected to the wellhead surface equipment via cables, enabling intelligent stratified injection, downhole flow testing, and water injection volume adjustment in offshore oilfield water injection wells. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of an integrated intelligent water injection string for offshore oilfields provided in an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of a cable-passing, backwashable sealing body in an integrated intelligent water injection string for offshore oilfields, provided by an embodiment of the present invention.

[0047] Figure 3 This is a schematic diagram of the structure of the first intelligent water injection tool in an integrated intelligent water injection string for offshore oilfields, provided in an embodiment of the present invention.

[0048] Figure 4 This is an axial cross-sectional view of a cable protection coupling in an integrated intelligent water injection string for offshore oilfields, provided in an embodiment of the present invention.

[0049] Figure 5 This is a radial cross-sectional view of a cable protection coupling in an integrated intelligent water injection string for offshore oilfields, provided in an embodiment of the present invention.

[0050] Figure 6 This is a flowchart of an installation method for an integrated intelligent water injection string in an offshore oilfield, provided by an embodiment of the present invention.

[0051] Figure 7 This is a flowchart of a construction method for an integrated intelligent water injection string for offshore oilfields, provided by an embodiment of the present invention.

[0052] in:

[0053] 100. Sleeve;

[0054] 1. Oil pipe hanging;

[0055] 2. Upper oil pipe;

[0056] 3. First oil pipe; 3-1. First section; 3-2. Second section; 3-3. Third section;

[0057] 4. Second oil pipe; 4-1. Check valve; 4-2. Fourth section; 4-3. Fifth section;

[0058] 5. First cable clamp;

[0059] 6. Downhole safety valve;

[0060] 7. Second cable clamp;

[0061] 8. Clean the well sliding sleeve;

[0062] 9. Hydraulic control lines;

[0063] 10. First cable-through backwashable interlayer sealing tool; 10-1. First packer; 10-2. Cable-through backwashable positioning seal; 10-3. Cable-through backwashable seal body; 10-3-1. Pipe body; 10-3-2. Central flow channel; 10-3-3. Cable crossing channel; 10-3-4. First stepped surface; 10-3-5. Second stepped surface; 10-3-6. Third stepped surface; 10-3-7. First through hole; 10-3-8. Backwash inlet outer cylinder; 0-3-9, Backwash Inlet; 10-3-10, Backwash Inlet Piston; 10-3-11, Backwash Channel Outer Cylinder; 10-3-12, Backwash Outlet Outer Cylinder; 10-3-13, Backwash Outlet; 10-3-14, Connector; 10-3-15, Backwash Channel; 10-3-16, Sealing Module; 10-3-17, Spacer Ring; 10-3-18, Second Through Hole; 10-3-19, Backwash Outlet Piston; 10-3-20, Fastening Pin; 10-3-21, Snap Ring;

[0064] 11. Second cable-through backwashable interlayer sealing tool; 11-1. Second packer; 11-2. Cable-through backwashable insertion seal;

[0065] 12. Lower packer;

[0066] 13. Screen blind tube;

[0067] 14. First intelligent water injection tool; 14-1. Upper connector; 14-2. Sealing ring; 14-3. Outer pipe; 14-4. Lower connector; 14-5. Outlet short section; 14-6. Injection nozzle;

[0068] 15. Second intelligent water injection tool;

[0069] 16. Cable protection coupling; 16-1. Central tube; 16-1-1. First tube section; 16-1-2. Second tube section; 16-1-3. Cable protection channel; 16-1-4. Anti-rotation groove; 16-1-5. Oil pipe clamp; 16-2. Anti-rotation screw; 16-2-1. Preload spring; 16-3. Pressure ring; 16-3-1. Cable clamp; 16-3-2. Limiting hole;

[0070] 17-1, First cable; 17-2, Second cable. Detailed Implementation

[0071] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0072] Example 1: As Figure 1 As shown, an embodiment of the present invention provides an integrated intelligent water injection string for offshore oilfields, including a water injection string disposed inside the casing 100. The water injection string includes, from top to bottom, a tubing hanger 1, an upper tubing 2, a first tubing 3, a second tubing 4, and a check valve 4-1. The outer wall of the upper tubing 2 is provided with, from top to bottom, a first cable clamp 5, a downhole safety valve 6, a second cable clamp 7, and a well-washing sleeve 8. The downhole safety valve 6 is connected to the wellhead control equipment through a 1 / 4″ hydraulic control line 9. The well-washing sleeve 8 is installed on the upper tubing 2 through a tubing clip 16-1-5.

[0073] Specifically, the lower end of tubing hanger 1 is screwed to the upper end of upper tubing 2; the lower end of upper tubing 2 is screwed to the upper end of cable-connected backwashing positioning seal 10-2; the lower end of cable-connected backwashing positioning seal 10-2 is screwed to the upper end of first tubing 3; the lower end of first tubing 3 is screwed to the upper end of cable-connected backwashing insertion seal 11-2; the lower end of cable-connected backwashing insertion seal 11-2 is screwed to the upper end of second tubing 4, and the lower end of second tubing 4 is screwed to well-washing check valve 4-1. The upper tubing 2 corresponds to the upper part of the downhole sand control section. The first tubing 3 and the second tubing 4 correspond to the first and second sections of the sand control layer, respectively. The second cable-through backwashable interlayer packer 11 has a lower packer 12 on its lower side. The first cable-through backwashable interlayer packer 10 has a first packer 10-1 and a cable-through backwashable positioning seal 10-2 that cooperates with the first packer 10-1. The second cable-through backwashable interlayer packer 11 has a second packer 11-1 and a second packer 11-2 that cooperates with the second packer. The cable-through backwashable insertion seal 11-2 in device 11-1, the outer surfaces of the first packer 10-1 and the second packer 11-1 are both fitted to the inner surface of the casing 100, the lower end of the first packer 10-1 and the upper end of the second packer 11-1, and the lower end of the second packer 11-1 and the upper end of the lower packer 12 are all connected to the screen blind pipe 13. The first cable-through backwashable interlayer sealing tool 10 and the second cable-through backwashable interlayer sealing tool 11 are used to realize the isolation between water injection layers and the backwashing of water injection wells.

[0074] When water is injected into the well through the annulus between the casing 100 and the water injection string, the fluid can pass through the first cable-connected backwashable interlayer sealing tool 10 and the second cable-connected backwashable interlayer sealing tool 11 layer by layer, and enter the water injection string through the single-flow valve 4-1 for backwashing. This realizes the reverse well washing of the intelligent water injection well, which can reduce the risk of wellbore blockage and scaling.

[0075] Furthermore, such as Figure 2As shown, both the cable-through backwashable positioning seal 10-2 and the cable-through backwashable insertion seal 11-2 include a cable-through backwashable seal body 10-3. The cable-through backwashable seal body 10-3 includes a pipe body 10-3-1, a backwash inlet outer cylinder 10-3-8, a backwash inlet piston 10-3-10, a backwash channel outer cylinder 10-3-11, a backwash outlet outer cylinder 10-3-12, and a connector 10-3-14. The pipe body 10-3-1 has a central flow channel 10-3-2 running vertically through its middle section. A cable passage 10-3-3 runs vertically through the side wall of the pipe body 10-3-1. Both ends of the cable passage 10-3-3 are fitted with 1 / 4″ NPT threads. The outer wall of the pipe body 10-3-1 is a stepped surface, consisting of a first stepped surface 10-3-4, a second stepped surface 10-3-5, and a third stepped surface 10-3-6 with decreasing diameters from top to bottom. The side wall of the pipe body 10-3-1 has a first through hole 10-3-7. 7. Connects the outer upper end of the third step surface 10-3-6 and the central flow channel 10-3-2. The backwash inlet outer cylinder 10-3-8 is screwed to the second step surface 10-3-5. The backwash inlet outer cylinder 10-3-8 has a backwash inlet 10-3-9 corresponding to the position of the third step surface 10-3-6. An inner step surface is provided on the lower side of the backwash inlet 10-3-9 on the backwash inlet outer cylinder 10-3-8. The backwash inlet piston 10-3-10 is slidably sleeved between the upper end of the third step surface 10-3-6 and the backwash inlet outer cylinder 10-3-8. When the backwash inlet piston 10-3-10 moves downward, it abuts against the inner step surface. At this time, the backwash inlet piston 10-3-10 can close the backwash inlet 10-3-9. The upper end of the backwash channel outer cylinder 10-3-11 is screwed to the lower end of the backwash inlet outer cylinder 10-3-8. The upper end of the backwash outlet outer cylinder 10-3-12 is screwed to the lower end of the backwash channel outer cylinder 10-3-11, and the backwash outlet outer cylinder 10-3-12 has a backwash outlet 10-3-13 corresponding to the third step surface 10-3-6. The connector 10-3-14 is screwed to the lower end of the backwash outlet outer cylinder 10-3-12 and sleeved on the lower end of the pipe body 10-3-1. The inner circumference of the connector 10-3-14 is provided with a sealing groove, forming a seal with the body. Sealing Structure. A backwashing channel 10-3-15 is formed between the outer cylinder 10-3-11 and the pipe body 10-3-1, connecting the backwashing inlet 10-3-9 and the backwashing outlet 10-3-13. When the backwashing inlet piston 10-3-10 moves down to close the backwashing inlet 10-3-9, a sealing structure is formed between the backwashing inlet piston 10-3-10, the pipe body 10-3-1, the backwashing inlet outer cylinder 10-3-8, and the backwashing channel outer cylinder 10-3-11. When well washing is not required, the backwashing channel 10-3-15 can be closed through this sealing structure to prevent interlayer migration caused by the backwashing channel 10-3-15.

[0076] Furthermore, the outer diameter of the tube body 10-3-1 of the cable-backwashable insertion seal 11-2 is smaller than the inner diameter of the first packer 10-1, which facilitates the installation of the water injection string, allowing the cable-backwashable insertion seal 11-2 to pass through the first packer 10-1; the outer wall of the tube body 10-3-1 of the cable-backwashable positioning seal 10-2 is provided with a positioning step, the outer diameter of which is larger than the inner diameter of the first packer 10-1, allowing the cable-backwashable positioning seal 10-2 to be installed on the first packer 10-1 through the positioning step.

[0077] The cable passage 10-3-3 of the pipe body 10-3-1 is provided with 1 / 4″ NPT threads at both ends; the inner circumference of the connector 10-3-14 is provided with a sealing groove and a sealing ring, so that the connector 10-3-14 can form a seal with the pipe body 10-3-1. When the backwash inlet piston 10-3-10 moves down to close the backwash inlet 10-3-9, the backwash inlet piston 10-3-10 forms a sealing structure with the pipe body 10-3-1, the backwash inlet outer cylinder 10-3-8, and the backwash channel outer cylinder 10-3-11. When well washing is not required, the backwash channel 10-3-15 can be closed to avoid interlayer cross-contamination caused by the backwash channel 10-3-15.

[0078] Furthermore, the outer cylinder 10-3-11 of the backwash channel is provided with an array of sealing modules 10-3-16, and spacers 10-3-17 are provided between the array of sealing modules 10-3-16. The sealing modules 10-3-16 can form an interference fit with the first packer 10-1, the second packer 11-1, or the lower packer 12 to seal the upper and lower layers.

[0079] Furthermore, the side wall of the pipe body 10-3-1 is provided with a second through hole 10-3-18, which connects the outer side of the lower end of the third step surface 10-3-6 and the central flow channel 10-3-2.

[0080] The cable-connected backwashable sealing body 10-3 also includes a backwash outlet piston 10-3-19 and a retaining ring 10-3-21. The backwash outlet piston 10-3-19 is slidably sleeved between the backwash outlet outer cylinder 10-3-12, the inner wall of the upper side of the connector 10-3-14, and the tube body 10-3-1. The lower outer side of the backwash outlet piston 10-3-19 is provided with a first retaining tooth, and the lower side of the backwash outlet piston 10-3-19 is provided with a fastening pin hole. The tube body 10-3-1 is provided with a fastening pin groove corresponding to the fastening pin hole. The backwash outlet piston 10-3-19 is fixed to the lower side of the tube body 10-3-1 by fastening pins 10-3-20 installed in the fastening pin hole and fastening pin groove. The retaining ring 10-3-21 adopts an open C-shaped structure. The inner wall of the retaining ring 10-3-21 is provided with a second retaining tooth that engages with the first retaining tooth. The second retaining tooth can guide the first retaining tooth to move upward and prevent the first retaining tooth from moving downward.

[0081] When the backwash outlet piston 10-3-19 moves upward to close the backwash outlet 10-3-13, the backwash outlet piston 10-3-19 forms a sealing structure with the pipe body 10-3-1 and the backwash outlet outer cylinder 10-3-12. At this time, the second locking tooth prevents the first locking tooth from moving downward, which can ensure that the backwash outlet piston 10-3-19 will not move in the opposite direction. This ensures that the backwash channel 10-3-15 of the cable-through backwash positioning seal 10-2 and the cable-through backwash insertion seal 11-2 are completely closed, which can prevent inter-layer migration due to multiple well washings.

[0082] Furthermore, such as Figure 3 As shown, the first oil pipe 3 is equipped with a first intelligent water injection tool 14, and the second oil pipe 4 is equipped with the same second intelligent water injection tool 15. The first oil pipe 3 includes a first section 3-1, the upper end of the first section 3-1 is screwed to the lower end of the first cable-through backwashable interlayer sealing tool 10, and the lower end of the first section 3-1 is screwed to the upper end of the first intelligent water injection tool 14. The first intelligent water injection tool 14 includes an upper connector 14-1, a sealing ring 14-2, an outer tube 14-3, and a lower connector 14-4. The upper end of the sealing ring 14-2 is screwed to the lower end of the upper connector 14-1. The upper end of the outer tube 14-3 is screwed to the lower end of the sealing ring 14-2. The outer tube 14-3 contains an integrated control board, a pressure testing section, a control motor, and a water nozzle adjustment module. The upper end of the lower connector 14-4 is screwed to the lower end of the outer tube 14-3. The lower connector 14-4 has a water outlet section 14-5, which has an injection nozzle 14-6. A differential pressure flow meter is installed inside the water outlet section 14-5. Both the upper connector 14-1 and the lower connector 14-4 have cable connectors. The second intelligent water injection tool 15 is connected to the first intelligent water injection tool 14 via a cable, and the first intelligent water injection tool 14 is connected to the wellhead surface equipment via a cable. Preferably, the cable is a 1 / 4″ steel pipe cable. Offshore oilfields suffer from severe inter-layer heterogeneity and large inter-layer injection pressure differentials. The first intelligent water injection tool 14 and the second intelligent water injection tool 15 can use the cable to adjust the water injection volume and monitor downhole parameters at each layer. A multi-stage fine water injection process is employed to precisely control the water injection volume at each layer, achieving a highly efficient water injection and production enhancement effect. Furthermore, the cable is fixed to the upper tubing 2 using cable clamps, providing protection for the cable above the sand control section.

[0083] Furthermore, such as Figure 4 , Figure 5As shown, the first oil pipe 3 is also equipped with a cable protection coupling 16. The first oil pipe 3 includes a second section 3-2 and a third section 3-3. The upper end of the second section 3-2 is screwed to the lower end of the first intelligent water injection tool 14, and the lower end of the second section 3-2 is screwed to the upper end of the cable protection coupling 16. The upper end of the third section 3-3 is screwed to the lower end of the cable protection coupling 16, and the lower end of the third section 3-3 is screwed to the upper end of the second cable backwashable interlayer sealing tool 11. The cable protection coupling 16 includes a central tube 16-1 and a pressure ring 16-3. The outer wall of the central tube 16-1 is provided with a cable protection channel 16-1-3 that runs through it. The channel includes a first tube section 16-1-1 and a second tube section 16-1-2 from top to bottom. The diameter of the first tube section 16-1-1 is smaller than the diameter of the second tube section 16-1-2. The lower end of the first tube section 16-1-1 is provided with an anti-rotation groove 16-1-4, in which an anti-rotation screw 16-2 is screwed. The pressure ring 16-3 is screwed to the lower end of the first tube section 16-1-1. The side wall of the pressure ring 16-3 is provided with a cable clamp 16-3-1 that runs through it along its axial direction and several limiting holes 16-3-2. The limiting holes 16-3-2 facilitate the screwing of the anti-rotation screw 16-2. The central tube 16-1 has oil pipe buckle 16-1-5 structure at both ends, and the central tube 16-1 has chamfers at both ends and a smooth outer circumference. The cable protection channel 16-1-3 has a rectangular structure, and the depth at both ends is less than the depth in the middle. Several cable protection channels 16-1-3 can be provided, and the several cable protection channels 16-1-3 are evenly distributed along the outer circumference of the central tube 16-1. The cable bayonet 16-3-1 has chamfers with outward expansion on both sides along its length direction. The chamfer can be set to 20° to facilitate the insertion of the cable into the cable bayonet 16-3-1. The limiting hole 16-3-2 has a waist-shaped hole structure and is evenly distributed along the circumference of the pressure ring 16-3. Preferably, the anti-rotation screw 16-2 includes a head with a larger diameter and a shank with a smaller diameter. The head has a fully threaded structure and the outer circumference of the shank is smooth. Currently, during the installation of the sand control section pipe column, the outer sheath of the steel pipe cable needs to be removed at the oil pipe coupling, which results in long construction time and many procedures. This cable protection coupling 16 does not require the removal of the outer sheath of the steel pipe cable and can achieve cable protection within the corresponding sand control section.

[0084] Furthermore, the anti-rotation groove 16-1-4 includes an outer part and an inner part. The diameter of the outer part is larger than that of the inner part. The outer part is used to screw the anti-rotation screw 16-2, and the inner part is used to accommodate the preload spring 16-2-1. When the anti-rotation screw 16-2 is screwed into the outer part, the preload spring 16-2-1 is pressed into the inner part, which makes it easy to screw the anti-rotation screw 16-2 into the limiting groove of the pressure ring 16-3.

[0085] The second tubing 4 includes a fourth section 4-2 and a fifth section 4-3. The upper and lower ends of the fourth section 4-2 are respectively screwed to the lower end of the second cable-connected backwashable interlayer sealing tool 11 and the upper end of the second intelligent water injection tool 15. The upper and lower ends of the fifth section 4-3 are respectively screwed to the lower end of the second intelligent water injection tool 15 and the upper end of the well-washing single-flow valve 4-1.

[0086] The cables include a first cable 17-1 and a second cable 17-2. The upper end of the first cable 17-1 connects to the surface equipment at the wellhead, and the lower end passes through the tubing hanger 1, the first cable clamp 5, the second cable clamp 7, and the cable backwashable positioning seal 10-2 to connect to the upper end of the first intelligent water injection tool 14, enabling the surface equipment to supply power to the downhole equipment, send commands, and transmit signals bidirectionally between the surface and the downhole. The upper end of the second cable 17-2 connects to the lower end of the first intelligent water injection tool 14, and the lower end passes through the cable protection coupling 16 and the cable passage through the cable backwashable insertion seal 11-2 to connect to the upper end of the second intelligent water injection tool 15. Above the sand control section, the first cable clamp 5 and the second cable clamp 7 protect the first cable 17-1. Below the sand control section, the cable protection coupling 16 protects the second cable 17-2.

[0087] Example 2: Figure 6 As shown, this embodiment of the invention provides a method for installing an integrated intelligent water injection string for offshore oilfields, used for installing the integrated intelligent water injection string for offshore oilfields as described in any of the above technical solutions, including the following steps:

[0088] Step 11: Install the first packer, the second packer, and the lower packer inside the casing, so that the first packer is located above the sandproof section, the second packer corresponds to the area between the first and second sections of the sandproof layer, and the lower packer corresponds to the area between the second and lower parts of the second section of the sandproof layer.

[0089] Step 12: Lower the water injection tubing into the well, so that the cable-through backwashable positioning seal of the water injection tubing is fitted with the first packer, and the cable-through backwashable insertion seal is fitted with the second packer.

[0090] Furthermore, before the water injection string is lowered into the casing, the cable can be passed through the cable protection coupling. This operation includes the following steps:

[0091] Step a: Install the cable protection coupling onto the first oil pipe.

[0092] Step b: Place the preload spring inside the anti-rotation groove of the central tube, screw the anti-rotation screw onto the outside of the anti-rotation groove, and tighten the preload spring.

[0093] Step c: Attach the pressure ring to the lower end of the first tube section, tighten the pressure ring, and then reverse the tightening by half a turn. ，Rotate the pressure ring to align the cable clamp of the pressure ring with a cable protection channel in the center tube.

[0094] Step d: Press the cable at the bottom of the cable protection channel, rotate the pressure ring to align a limiting hole with the anti-rotation groove, at which point the cable protection channel of the central tube is blocked by the pressure ring.

[0095] Step e: Rotate the anti-rotation screw in the opposite direction until it is inside the limiting groove of the pressure ring, thus completing the installation of the cable in the cable protection coupling.

[0096] Example 3: Figure 7 As shown, this embodiment of the invention provides a construction method for an integrated intelligent water injection string in offshore oilfields, applied to the integrated intelligent water injection string in offshore oilfields described in any of the above technical solutions. This construction method is used to achieve annular well washing and includes the following steps:

[0097] Step 21: Water is injected into the well from the ground through the gap between the injection tubing and the casing annulus. The fluid pushes the backwash inlet piston, which is sealed by the cable, upward through the backwash inlet, connecting the backwash inlet, backwash channel and backwash outlet. The fluid flows into the first layer and can clean the blockage between the injection tubing and the sand screen blind pipe corresponding to the first layer.

[0098] Step 22: The fluid pushes the piston of the backwash inlet, which can be inserted into the cable and is sealed, upward, connecting the backwash inlet, backwash channel and backwash outlet. The fluid mixed with some blockage flows into the second layer, cleaning the blockage between the water injection pipe and the blind pipe of the sand screen corresponding to the second layer.

[0099] Step 23: The fluid mixed with a lot of blockage finally enters the water injection string through the one-way valve at the bottom of the water injection string, and backwashes the blockage in the wellbore out through the central wellhead, which can completely close the backwash channel.

[0100] Furthermore, the fluid containing a significant amount of blockage material eventually enters the injection string through the check valve at the bottom of the injection string. After backwashing out the blockage material from the wellbore through the central wellhead, it also includes:

[0101] Step 24: Pressurize the water injection string at the wellhead until the fluid passes through the second through hole and pushes the fastener of the backwash outlet piston of the cable-connected backwash positioning seal and the cable-connected backwash insertion seal to break. The backwash outlet piston moves upward, and the second retaining tooth of the retaining ring engages with the first retaining tooth of the backwash outlet piston to limit the backwash outlet piston. The backwash channels of the cable-connected backwash positioning seal and the cable-connected backwash insertion seal are completely closed, ensuring that the backwash outlet piston will not move in the opposite direction.

[0102] When the piston sealing surface of the cable-backwashable positioning seal and the cable-backwashable insertion packer is eroded and cannot be completely sealed after multiple well washes, in order to avoid interlayer flow, pressure is applied to the water injection string through the wellhead to completely close the backwashing channels of the cable-backwashable positioning seal and the cable-backwashable insertion seal, thus preventing interlayer flow caused by multiple well washes.

[0103] Example 4: This embodiment of the invention provides a construction method for an integrated intelligent water injection string for offshore oilfields, applicable to any of the above-described technical solutions. This construction method is used for layered water injection into the first and second sections, and includes the following steps:

[0104] Step 31: Water is injected into the water injection pipe column. Water is injected into the first layer and the second layer respectively through the first intelligent water injection tool and the second intelligent water injection tool. Water injection isolation between the first layer and the upper part of the sand prevention section is achieved by the backwashable positioning seal through the cable and the first packer. Water injection isolation between the first layer and the second layer is achieved by the backwashable insertion seal through the cable and the second packer.

[0105] Among them, the cable-backwashable positioning seal cooperates with the first packer and is positioned at the NO-GO position inside the first packer to achieve annular sealing corresponding to the first layer and the sandproof section above; the cable-backwashable insertion packer cooperates with the second packer to achieve pressure sealing corresponding to the first layer and the second layer.

[0106] Step 32: The ground equipment controls the first and second intelligent water injection tools via cables. The first and second intelligent water injection tools monitor the water injection pressure, flow rate, and temperature parameters of the first and second layers. The injection pressure and flow rate parameters of each layer are transmitted to the ground equipment via cables. The opening of the injection nozzles of the first and second intelligent water injection tools is adjusted according to the ground injection volume requirements, so as to realize the monitoring of the water injection parameters and the adjustment of the water injection volume of the first and second layers.

[0107] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An integrated intelligent water injection string for offshore oilfields, characterized in that, The system includes a water injection string installed inside the casing. From top to bottom, the water injection string includes a tubing hanger, an upper tubing, a first tubing, a second tubing, and a check valve. The tubing hanger is located above the upper tubing, which corresponds to the upper part of the downhole sand control section. The first and second tubings correspond to the first and second layers of the sand control layer, respectively. A first cable-through backwashable interlayer sealing tool is installed between the upper tubing and the first tubing. A second cable-through backwashable interlayer sealing tool is installed between the first and second tubings. The lower side of the second cable-through backwashable interlayer sealing tool is equipped with... The first cable-through backwashable interlayer packer has a lower packer, and the second tubing has a check valve at the lower end. The first cable-through backwashable interlayer packer has a first packer and a cable-through backwashable positioning seal that fits in the first packer. The second cable-through backwashable interlayer packer has a second packer and a cable-through backwashable insertion seal that fits in the second packer. The outer surfaces of the first packer and the second packer both fit in the inner surface of the casing. The first cable-through backwashable interlayer packer and the second cable-through backwashable interlayer packer are used to achieve water injection interlayer isolation and water injection well backwashing. When water is injected into the well through the annulus between the casing and the injection string, the fluid can pass through the first cable-through backwashable interlayer sealing tool and the second cable-through backwashable interlayer sealing tool layer by layer, and enter the injection string through the single-flow valve for backwashing. Both the cable-through backwashable positioning seal and the cable-through backwashable insertion seal include a cable-through backwashable seal body, which includes: The tube body has a central flow channel that runs vertically through its middle section. The side wall of the tube body has a cable passage channel that runs vertically through it. The outer wall of the tube body is a stepped surface. The stepped surface includes a first stepped surface, a second stepped surface, and a third stepped surface with decreasing diameters from top to bottom. The side wall of the tube body has a first through hole that connects the outer upper part of the third stepped surface and the central flow channel. The backwash inlet outer cylinder is screwed to the second step surface. The backwash inlet outer cylinder is provided with a backwash inlet corresponding to the position of the third step surface. An inner step surface is provided on the lower side of the backwash inlet on the backwash inlet outer cylinder. The backwash inlet piston is slidably sleeved between the upper side of the third step surface and the backwash inlet outer cylinder. When the backwash inlet piston moves down and abuts against the inner step surface, the backwash inlet piston can close the backwash inlet. The upper end of the backwash channel outer cylinder is screwed to the lower end of the backwash inlet outer cylinder; The upper end of the backwash outlet outer cylinder is screwed to the lower end of the backwash channel outer cylinder, and the backwash outlet outer cylinder is provided with a backwash outlet corresponding to the position of the third step surface. The connector is screwed to the lower end of the backwash outlet outer cylinder and sleeved on the lower end of the pipe body; The backwash channel outer cylinder and the pipe body form a backwash channel that can connect the backwash inlet and the backwash outlet; The outer wall of the cable-through backwashable positioning seal tube is provided with a positioning step, the outer diameter of which is larger than the inner diameter of the first packer; the outer diameter of the cable-through backwashable insertion seal tube is smaller than the inner diameter of the first packer. The sidewall of the tube is provided with a second through hole, which connects the outer side of the lower end of the third stepped surface and the central flow channel. The cable-washable sealing body also includes: The backwash outlet piston is slidably sleeved between the backwash outlet outer cylinder, the inner wall of the upper side of the connector, and the tube body. The lower outer side of the backwash outlet piston is provided with a first locking tooth, and the lower side of the backwash outlet piston is provided with a fastening pin hole. The tube body is provided with a corresponding fastening pin groove. The backwash outlet piston is fixed to the lower side of the tube body by fastening pins installed in the fastening pin hole and the fastening pin groove. The retaining ring adopts an open C-shaped structure. The inner wall of the retaining ring is provided with a second retaining tooth that engages with the first retaining tooth. The second retaining tooth can guide the first retaining tooth to move upward and prevent the first retaining tooth from moving downward.

2. The integrated intelligent water injection string for offshore oilfields as described in claim 1, characterized in that, The first tubing is equipped with a first intelligent water injection tool, and the second tubing is equipped with an identical second intelligent water injection tool. The first tubing includes a first section, the upper end of which is screwed to the lower end of the first cable-connected backwashable interlayer sealing tool, and the lower end of which is screwed to the upper end of the first intelligent water injection tool. The first intelligent water injection tool includes: an upper connector; a sealing ring, the upper end of which is screwed to the lower end of the upper connector; an outer tube, the upper end of which is screwed to the lower end of the sealing ring, and the outer tube contains an integrated control board, a pressure testing sub, a control motor, and a water nozzle adjustment module; a lower connector, the upper end of which is screwed to the lower end of the outer tube, and the lower connector has a water outlet sub, which has an injection nozzle, and a differential pressure flow meter is installed inside the water outlet sub; both the upper and lower connectors are equipped with cable connectors; the second intelligent water injection tool is connected to the first intelligent water injection tool via a cable, and the first intelligent water injection tool is connected to the wellhead surface equipment via a cable.

3. The integrated intelligent water injection string for offshore oilfields as described in claim 2, characterized in that, The first oil pipe is also equipped with a cable protection coupling. The first oil pipe includes a second section and a third section. The upper end of the second section is screwed to the lower end of the first intelligent water injection tool, and the lower end of the second section is screwed to the upper end of the cable protection coupling. The upper end of the third section is screwed to the lower end of the cable protection coupling, and the lower end of the third section is screwed to the upper end of the second cable-through backwashable interlayer sealing tool. The cable protection coupling includes: The central tube has a cable protection channel running through its outer wall. It consists of a first tube section and a second tube section from top to bottom. The diameter of the first tube section is smaller than the diameter of the second tube section. An anti-rotation groove is provided on the lower end side of the first tube section, and an anti-rotation screw is screwed into the anti-rotation groove. A pressure ring is screwed to the lower end of the first tube. The side wall of the pressure ring is provided with a cable clamp that passes through along its axis and several limiting holes. The limiting holes facilitate the screwing of the anti-rotation screw.

4. The integrated intelligent water injection string for offshore oilfields as described in claim 3, characterized in that, The anti-rotation groove includes an outer part and an inner part. The diameter of the outer part is larger than that of the inner part. The outer part is used to screw on the anti-rotation screw, and the inner part is used to accommodate the preload spring. When the anti-rotation screw is screwed on the outer part, the preload spring is pressed against the inner part.

5. A method for installing an integrated intelligent water injection string for offshore oilfields, used to install the integrated intelligent water injection string for offshore oilfields as described in claim 4, characterized in that, include: The first packer, the second packer, and the lower packer are installed inside the casing, with the first packer positioned above the sand-proof section, the second packer corresponding to the area between the first and second sections of the sand-proof layer, and the lower packer corresponding to the area between the second and lower sections of the sand-proof layer. The water injection tubing is lowered into the well so that the cable-through backwashable positioning seal of the water injection tubing is fitted to the first packer, and the cable-through backwashable insertion seal is fitted to the second packer.

6. The installation method of the integrated intelligent water injection string for offshore oilfields as described in claim 5, characterized in that, Before the water injection tubing is lowered into the casing, the following steps are included: Install the cable protection coupling onto the first oil pipe; The preload spring is placed inside the anti-rotation groove of the central tube, and the anti-rotation screw is screwed onto the outside of the anti-rotation groove and the preload spring is pressed. The pressure ring is screwed to the lower end of the first tube. The pressure ring is tightened and then reversed half a turn. The pressure ring is rotated so that the cable clamp of the pressure ring is aligned with a cable protection channel of the central tube. Press the cable down to the bottom of the cable protection channel, rotate the pressure ring, and align one of the limiting holes with the anti-rotation groove; Rotate the anti-rotation screw in the opposite direction to rotate it into the limiting groove of the pressure ring.

7. A construction method for an integrated intelligent water injection string for offshore oilfields, applied to the integrated intelligent water injection string for offshore oilfields as described in any one of claims 1 to 4, characterized in that, include: Water is injected into the well from the ground through the gap between the water injection tubing and the casing annulus. The fluid pushes the backwash inlet piston, which is backwashable and positioned by the cable, upward through the backwash inlet, connecting the backwash inlet, backwash channel and backwash outlet. The fluid flows into the first layer and cleans the blockage between the water injection tubing and the sand screen blind pipe corresponding to the first layer. Fluid pushes the piston of the backwash inlet, which can be inserted into the cable and is sealed, to move upward, connecting the backwash inlet, backwash channel and backwash outlet. Fluid mixed with some blockages flows into the second layer, cleaning the blockages between the water injection pipe and the sand screen blind pipe corresponding to the second layer. The fluid containing a large amount of blockage eventually enters the water injection string through the one-way valve at the bottom of the water injection string, and backwashes out the blockage in the wellbore through the central wellhead.

8. The construction method of the integrated intelligent water injection string for offshore oilfields as described in claim 7, characterized in that, The fluid containing a large amount of blockage material eventually enters the water injection string through the one-way valve at the bottom of the water injection string. After backwashing the blockage material in the wellbore through the central wellhead, the process also includes: pressurizing the water injection string at the wellhead until the fluid pushes the fastener of the backwash outlet piston of the cable-connected backwashable positioning seal and the cable-connected backwashable insertion seal through the second through hole, causing the fastener to break and the backwash outlet piston to move upward. The second tooth of the retaining ring engages with the first tooth of the backwash outlet piston to limit the backwash outlet piston. The backwash channels of the cable-connected backwashable positioning seal and the cable-connected backwashable insertion seal are completely closed.

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