Layered water injection tubular column

Abstract

The invention discloses a layered water injection tubular column. The technical problem that in the prior art, when a tubular column externally bound with a cable is put into a deformed sleeve, the cable is prone to being damaged is solved. The connecting structure comprises a conventional pipe, a penetrating pipe, a prefabricated pipe and a connecting assembly. A fixing part is arranged outside the conventional pipe to bind a cable; the penetrating pipe sleeves the conventional pipe and is internally provided with a first cable channel; a second cable channel is formed in the prefabricated pipe; the connecting assembly comprises a first connecting terminal arranged in the penetrating pipe and a second connecting terminal arranged in the prefabricated pipe which are electrically connected, the first connecting terminal is electrically connected with a cable in the first cable channel, and the second connecting terminal is electrically connected with a cable in the second cable channel. The cable is converted from the external to the internal or from the internal to the external; when a target well where a pipe column needs to be arranged deforms, a conventional pipe can be arranged below the non-deformation area, and a prefabricated pipe can be arranged below the deformation area, so that the inner wall of a deformation sleeve is prevented from abrading and breaking a protection layer of a cable, and the risk of pulling out and well clamping is avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of cable-controlled intelligent stratified water injection in the petroleum industry, and specifically relates to a stratified water injection string. Background Art

[0002] Water injection is an effective method to maintain reservoir pressure, achieve high and stable production of oil fields, and improve the development effect of oil fields. About 92% of the reservoirs in my country's oil fields are continental clastic rock deposits with strong vertical heterogeneity. During the water injection development process, the injected water is easy to channel along the high permeability layer, resulting in inefficient and ineffective water injection. Developing stratified water injection technology to achieve effective water injection in multiple oil layers is an important means to continue to improve water drive recovery during high water content and ultra-high water content periods. Stratified water injection technology uses cables and carrier technology to power the downhole cable-controlled intelligent water distributor, and provides communication between the cable-controlled water distributor and the ground control device, so as to achieve real-time collection of stratum flow, pressure, nozzle opening and temperature parameters and real-time adjustment of injection volume under stratified water injection.

[0003] The existing cable-controlled process string uses cables bundled outside the string. During the lowering process, various problems are often encountered. For example, for special well conditions such as casing change wells or side drilling wells, when the string is lowered to the casing change area or side drilling area, the deformed inner wall of the casing may wear through or break the protective layer of the cable, resulting in cable insulation failure and signal loss, which cannot meet the process requirements. Summary of the invention

[0004] In order to solve the technical problem in the current prior art that a layered water injection string with externally bundled cables is prone to cable damage when being lowered into a casing deformation zone, the present application provides a layered water injection string.

[0006] In a first aspect of the present application, a layered water injection string is provided, comprising a conventional pipe, a crossing pipe, a prefabricated pipe and a connection assembly;

[0007] The conventional tube is provided with a fixing portion for binding the cable on the outside;

[0008] The through-tube has one end sleeved on the conventional tube, and the interior of the through-tube has a first cable channel for the cable to pass through;

[0009] The prefabricated tube has a second cable channel inside for the cable to pass through;

[0010] The connection assembly includes a first connection terminal and a second connection terminal. The first connection terminal is arranged in the crossing tube and can be electrically connected to the cable in the first cable channel. The second connection terminal is arranged in the prefabricated tube and can be electrically connected to the cable in the second cable channel. The first connection terminal and the second connection terminal are electrically connected.

[0011] In some embodiments, one of the first connection terminal and the second connection terminal has an inserting portion, and the other has an inserting slot, and the inserting portion is inserted into the inserting slot to electrically connect the first connection terminal to the second connection terminal.

[0012] In some embodiments, a spring is provided in the plug-in slot along the axial direction of the plug-in slot.

[0013] In some embodiments, the first connection terminal includes a first fixed disk, a first power-carrying ring and a first connecting portion, the first power-carrying ring is fixed on the first fixed disk, the first connecting portion is electrically connected to the first power-carrying ring, and the first power-carrying ring is used to electrically connect to the cable.

[0014] In some embodiments, the first fixing plate has a first water passage communicating with the interior of the conventional tube.

[0015] In some embodiments, the second connecting terminal includes a second fixed disk, a second power-carrying ring and a second connecting portion, the second power-carrying ring is fixed on the second fixed disk, the second connecting portion is electrically connected to the second power-carrying ring, and the second power-carrying ring is used to electrically connect to the cable.

[0016] In some embodiments, the first fixing plate has a first water passage communicating with the interior of the conventional tube.

[0017] In some embodiments, a portion of the first cable channel is disposed outside the conventional tube.

[0018] In some embodiments, the crossing tube includes a first tube segment and a second tube segment, the first tube segment is sleeved in the conventional tube, the first connecting terminal is arranged in the second tube segment, the first cable channel includes a first channel segment and a second channel segment connected to each other, the first channel segment is arranged in the first tube segment, the second channel segment is arranged in the second tube segment, and the opening area of ​​the first channel segment is larger than the opening area of ​​the second channel segment. In some embodiments, the conventional pipe or the prefabricated pipe has a drain port, and the stratified water injection column also includes a differential pressure switch, which is installed at the drain port. The differential pressure switch includes a differential pressure tube body, a connecting seat and a switch component; the differential pressure tube body is provided with a second water passage; the connecting seat is a rotating body, which is connected to the inner wall of the differential pressure tube body along the circumference of the differential pressure tube body, dividing the second water passage into two sub-channels; the connecting seat is provided with a water passage running through the connecting seat, and the water passage connects the two divided sub-channels; the switch component is arranged at the front end of the connecting seat along the water flow direction, and can reciprocate along the axial direction of the differential pressure tube body to abut or be spaced from the connecting seat, so that the water passage is disconnected or connected with the second water passage.

[0019] The layered water injection pipe column provided according to the embodiment of the present application includes a conventional pipe, a crossing pipe, a prefabricated pipe and a connecting assembly; a fixing portion for binding cables is arranged on the outside of the conventional pipe; one end of the crossing pipe is sleeved on the conventional pipe, and the interior of the crossing pipe has a first cable channel for the cable to pass through; the prefabricated pipe has a second cable channel for the cable to pass through; the connecting assembly includes a first connecting terminal and a second connecting terminal, the first connecting terminal is arranged in the crossing pipe and can be electrically connected to the cable in the first cable channel, the second connecting terminal is arranged in the prefabricated pipe and can be electrically connected to the cable in the second cable channel, and the first connecting terminal and the second connecting terminal are electrically connected.

[0020] The layered water injection string of the present application has a fixing portion for binding the cable on the outside of the conventional pipe, that is, the cable is located on the outside of the conventional pipe body; the prefabricated pipe has a second cable channel for the cable to pass through, that is, the cable is located inside the prefabricated pipe body; one end of the crossing pipe is sleeved on the conventional pipe, and the other end is connected to the prefabricated pipe through a connecting component, that is, the conventional pipe and the prefabricated pipe are connected through the crossing pipe, so that the cable is transformed from the external device of the conventional pipe to the internal device of the prefabricated pipe or from the internal device of the prefabricated pipe to the external device of the conventional pipe; when there is a deformed area in the target well where the string needs to be lowered, such as a casing change well and a side drilling well, a conventional pipe for binding the cable on the outside can be lowered in the undeformed casing area, and a prefabricated pipe through which the cable can pass can be lowered in the deformed casing area, so as to prevent the deformed casing inner wall from wearing through and breaking the protective layer of the cable when the string is lowered to the casing change area or the side drilling area, thereby avoiding cable insulation failure and signal loss. The prefabricated pipe protects the cable, and there is no need to lower a special cable protection clip, which solves the problem of lowering the tool and avoids the risk of well jamming. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic structural diagram of a casting-free and scooping-free injection system according to an embodiment of the present application is shown.

[0022] Figure 2 A schematic diagram of a prefabricated tube in a dredging-free dispenser according to an embodiment of the present application is shown.

[0023] Figure 3 A schematic diagram showing the connection of multiple prefabricated pipes in a cast-free dispenser according to an embodiment of the present application is shown.

[0024] Figure 4 A schematic diagram of the connection between the first connecting terminal and the second connecting terminal in the casting-free dispensing device of an embodiment of the present application is shown.

[0025] Figure 5 A schematic diagram of a crossing pipe in a casting-free dispensing device according to an embodiment of the present application is shown.

[0026] Figure 6A schematic diagram of the assembly of the prefabricated pipe and the through pipe in the cast-free dispenser of the embodiment of the present application is shown.

[0027] Figure 7 The figure shows the assembly diagram of the conventional tube and the through tube in the cast-and-dredge-free dispenser according to the embodiment of the present application.

[0028] Figure 8 A schematic diagram of opening the pressure difference switch in the casting-free dispensing device according to an embodiment of the present application is shown.

[0029] Fig. 9 A schematic diagram of closing the pressure difference switch in the casting-free dispensing device according to an embodiment of the present application is shown.

[0030] Description of reference numerals:

[0031] 100, conventional tube;

[0032] 200, through the pipe;

[0033] 300, prefabricated pipe;

[0034] 310, first connection terminal; 320, second connection terminal;

[0035] 311, first fixed plate; 312, first energizing circle;

[0036] 400, differential pressure switch;

[0037] 410, upper connector; 420, connector; 430, lower connector; 440, connector seat; 450, switch member; 460, spring;

[0038] 500, Packer;

[0039] 600, hanger;

[0040] 700, water distributor;

[0041] 800, cable;

[0042] 900, oil layer;

[0043] 1000, side drilling inclined well section; 1100, vertical well section. DETAILED DESCRIPTION

[0044] In order to make the technical personnel in the technical field to which the present application belongs to understand the present application more clearly, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0045] An embodiment of the present application provides a layered water injection string, which, when the string is lowered into a casing-changed well or a side-drilling well, prevents the deformed inner wall of the casing from wearing through or cutting off the protective layer of the cable.

[0046] See also Figure 1 The layered water injection pipe string provided in the embodiment of the present application includes a conventional pipe 100, a crossing pipe 200, a prefabricated pipe 300 and a connection assembly; the conventional pipe 100 is provided with a fixing portion for binding a cable 800 on the outside; please refer to Figure 5 One end of the through tube 200 is sleeved on the conventional tube 100, and the interior of the through tube 200 has a first cable channel for the cable 800 to pass through; see Figure 2 The prefabricated tube 300 has a second cable passage inside for the cable 800 to pass through; see Figure 6 as well as Figure 7 The connection assembly includes a first connection terminal 310 and a second connection terminal 320. The first connection terminal 310 is arranged in the crossing tube 200 and can be electrically connected to the cable 800 in the first cable channel. The second connection terminal 320 is arranged in the prefabricated tube 300 and can be electrically connected to the cable 800 in the second cable channel. The first connection terminal 310 and the second connection terminal 320 are electrically connected.

[0047] In some embodiments, the conventional pipe 100, the prefabricated pipe 300 and the through pipe 200 are all provided with a water channel, and the first cable channel and the second cable channel are not connected to the water channel; see Figure 2 In some embodiments, the prefabricated pipe 300 is provided with multiple sections of prefabricated pipes 300, and the multiple sections of prefabricated pipes 300 are connected through a first connecting terminal 310 and a second connecting terminal 320; in some embodiments, the cable 800 of the conventional pipe 100 is externally bound, passes through the first cable channel into the interior of the crossing pipe 200, and is connected to the first connecting terminal 310, and the first connecting terminal 310 is electrically connected to the second connecting terminal 320, so that the cable 800 external to the conventional pipe 100 is electrically connected to the cable 800 inside the prefabricated pipe 300.

[0048] See also Figure 4 In some embodiments, one of the first connection terminal 310 and the second connection terminal 320 has a plug-in portion and the other has a plug-in slot, and the plug-in portion is inserted into the plug-in slot so that the first connection terminal 310 is electrically connected to the second connection terminal 320 to further strengthen the electrical connection between the first connection terminal 310 and the second connection terminal 320; in some embodiments, the first connection terminal 310 has a plug-in portion, and the second connection terminal 320 has a plug-in slot, and both the plug-in slot and the plug-in portion are conductive.

[0049] In some embodiments, a spring 460 is provided in the plug-in slot along the axial direction of the plug-in slot to mitigate the impact force of the plug-in operation and protect the device.

[0050] See also Figure 4 In some embodiments, the first connection terminal 310 includes a first fixed disk 311, a first power-carrying ring 312 and a first connecting portion. The first power-carrying ring 312 is fixed on the first fixed disk 311. The first connecting portion is electrically connected to the first power-carrying ring 312. The first power-carrying ring 312 is used to be electrically connected to the cable 800. In some embodiments, the first fixed disk 311 includes a main body and an insulating layer coated on the main body to prevent leakage; in some embodiments, the first fixed disk 311 is made of insulating material to prevent leakage; in some embodiments, the first power-carrying ring 312 and the first connecting portion are conductive.

[0051] In some embodiments, the first fixing plate 311 has a first water passage communicating with the interior of the conventional pipe 100 .

[0052] See also Figure 4 In some embodiments, the second connection terminal 320 includes a second fixed disk, a second power-carrying ring and a second connecting portion. The second power-carrying ring is fixed on the second fixed disk, and the second connecting portion is electrically connected to the second power-carrying ring. The second power-carrying ring is used to be electrically connected to the cable 800. In some embodiments, the second fixed disk includes a main body and an insulating layer coated on the main body to prevent leakage; in some embodiments, the second fixed disk is made of insulating material to prevent leakage; in some embodiments, the second power-carrying ring and the second connecting portion are conductive.

[0053] In some embodiments, the first fixing plate 311 has a first water passage communicating with the interior of the conventional pipe 100 .

[0054] In some embodiments, part of the first cable channel is disposed outside the conventional pipe 100 , so that the cable 800 is connected to the first connection terminal 310 of the penetration pipe 200 from outside the conventional pipe 100 through the first cable channel.

[0055] See also Figure 5 In some embodiments, the crossing pipe 200 includes a first pipe section and a second pipe section, the first pipe section is sleeved in the conventional pipe 100, the first connecting terminal 310 is arranged in the second pipe section, the first cable channel includes a first channel section and a second channel section connected to each other, the first channel section is arranged in the first pipe section, the second channel section is arranged in the second pipe section, the opening area of ​​the first channel section is larger than the opening area of ​​the second channel section, so as to provide a basis for the cable 800 to pass through; in some embodiments, a cable 800 socket is provided in the first cable channel to provide support and guidance for the cable 800.

[0056] See also Figure 1 , Figure 8 as well as Fig. 9In some embodiments, the conventional pipe 100 or the prefabricated pipe 300 has a drain port, and the stratified water injection string further includes a differential pressure switch 400, which is installed at the drain port. The differential pressure switch 400 includes a differential pressure pipe body, a connecting seat 440 and a switch 450; the differential pressure pipe body is provided with a second water passage; the connecting seat 440 is a rotating body, which is connected to the inner wall of the differential pressure pipe body along the circumference of the differential pressure pipe body, and divides the second water passage into two sub-channels; the connecting seat 440 is provided with a connecting seat 440 that penetrates the connecting seat 440 The water passage connects the two divided sub-channels; the switch 450 is arranged at the front end of the connecting seat 440 along the water flow direction, and can reciprocate along the axial direction of the pressure difference pipe body to abut or be spaced from the connecting seat 440, so that the water passage is disconnected or connected with the second water passage; in some embodiments, the tail pipe is connected with a pressure difference switch 400; in some embodiments, the pressure difference pipe body includes an upper joint 410, a lower joint 430 and a connecting body 420, which are all rotating bodies; the upper joint 410 and the lower joint 430 is connected through a connector 420, and the upper connector 410, the lower connector 430 and the connector 420 are coaxial to form a second water passage; in some embodiments, the switch member 450 is a rotating body, provided with a first acting portion and a second acting portion fixedly connected and angled; in some embodiments, the first acting portion is a circular ring, and the second acting portion is a cylinder; in some embodiments, the inner wall of the pressure differential tube body is provided with a boss located between the first acting portion and the connecting seat 440 and extending radially along the pressure differential tube body; the inner wall of the pressure differential tube body, the boss and the switch member 450 together form a accommodating chamber; a spring 460 abutting against the first acting portion and the boss is provided in the accommodating chamber; the extension direction of the second acting portion is located between the axial direction of the pressure differential tube body and the axial direction of the water passage; the switch member 450 reciprocates along the axial direction of the pressure differential tube body, so that the second acting portion abuts against or is spaced from the connecting seat 440, so that the water passage is separated from or connected to the second water passage; in some embodiments, the first acting portion and the second acting portion are arranged at an angle of 90°.

[0057] The following is a detailed description of the use process of the layered water injection string of the present application:

[0058] Step 1, connect the differential pressure switch 400 and the tail pipe, and then connect the prefabricated pipe 300 and the conventional pipe 100 according to the well conditions, set down by the injection traction device, set the prefabricated pipe 300 in the casing deformation area, set the conventional pipe 100 in the casing non-deformation area, connect the conventional pipe 100 and the prefabricated pipe 300 through the crossing pipe 200, and reciprocately set down until the hanger sits on the wellhead; the cable 800 is set down with the conventional pipe 100 or the prefabricated pipe 300 to the position of the water distributor 700 and connected to the water distributor 700;

[0059] Step 2: Connect the cable 800 to the integrated control cabinet and calibrate the depth; after the cable 800 passes through, seal it in an appropriate manner;

[0060] Step 3, pressurizing the differential pressure switch 400 to make the switch member 450 abut against the connecting seat 440, so that the water passage is disconnected from the second water passage, and the packer 500 is set;

[0061] Step 4: Check seal and tampering;

[0062] Step 5: Connect the water injection pipeline for normal production.

[0063] The layered water injection string of the present application has at least the following advantages:

[0064] (1) The layered water injection string of the present application has a fixing portion for binding the cable on the outside of the conventional pipe, that is, the cable is located on the outside of the conventional pipe body; the prefabricated pipe has a second cable channel for the cable to pass through, that is, the cable is located inside the prefabricated pipe body; one end of the through pipe is sleeved on the conventional pipe, and the other end is connected to the prefabricated pipe through a connecting assembly, that is, the conventional pipe and the prefabricated pipe are connected through the through pipe, so that the cable is transformed from the external device of the conventional pipe to the internal device of the prefabricated pipe or from the internal device of the prefabricated pipe to the external device of the conventional pipe; when the target well where the string needs to be lowered has a deformed area, such as a casing change well and a side drilling well, a conventional pipe for binding the cable on the outside can be lowered in the undeformed casing area, and a prefabricated pipe for passing the cable inside can be lowered in the deformed casing area. The prefabricated pipe protects the cable to prevent the deformed casing inner wall from wearing through or breaking the protective layer of the cable when the string is lowered to the casing change area or the side drilling area, thereby avoiding cable insulation failure and signal loss. There is no need to lower a special cable protection clip, which solves the problem of lowering tools and avoids the risk of well jamming.

[0065] (2) The layered water injection pipe column of the present application has a spring disposed in the plug-in groove along the axial direction of the plug-in groove, so that the plug-in operation between the plug-in part and the plug-in groove can be buffered to protect the device.

[0066] (3) The layered water injection string of the present application is provided with a differential pressure switch. When no pressure is applied, the differential pressure switch remains in a normally open state under the action of a spring. When pressure is applied, the switch member of the differential pressure switch is moved toward the connecting seat by water flow pressure, so that the water passage is isolated from the second water passage, and the differential pressure switch is closed to complete the pressure application operation. When used for side drilling wells, since the side drilling wells have a window inflection point, the inner diameter of the hanger is small, and the inclination of the side drilling section is large, the existing technology uses a ball seat for pressure application, which has a large probability of error in throwing the ball. Compared with the existing technology, the differential pressure switch of the present application uses a reliable pressure switch instead of gravity, which avoids the problem of being unable to apply pressure due to the large angle of the small diameter side drilling wells. It has good practicality and a high success rate of pressure application.

[0067] (4) The layered water injection pipe column of the present application connects the prefabricated pipes with the prefabricated pipes and the prefabricated pipes with the crossing pipes through the first connecting terminal and the second connecting terminal. The first connecting terminal and the second connecting terminal are respectively provided with the first fixing plate and the second fixing plate, and the first fixing plate and the second fixing plate are made of insulating material, which can prevent the device from leaking electricity and affecting the use effect.

[0068] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0069] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise" and "counterclockwise" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0070] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0071] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0072] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A layered water injection string, characterized in that: include: Conventional tube, with a fixing portion for binding cables provided on the outside; A crossing pipe, one end of which is sleeved on the conventional pipe, and the interior of the crossing pipe has a first cable channel for the cable to pass through; A prefabricated pipe having a second cable passage therein for the cable to pass through; The connection assembly includes a first connection terminal and a second connection terminal, wherein the first connection terminal is arranged in the through tube and can be electrically connected to the cable in the first cable channel, and the second connection terminal is arranged in the prefabricated tube and can be electrically connected to the cable in the second cable channel, and the first connection terminal and the second connection terminal are electrically connected.

2. The layered water injection string according to claim 1, characterized in that: One of the first connection terminal and the second connection terminal has an inserting portion, and the other has an inserting slot, and the inserting portion is inserted into the inserting slot to electrically connect the first connection terminal to the second connection terminal.

3. The layered water injection string according to claim 2, characterized in that: A spring is arranged in the inserting slot along the axial direction of the inserting slot.

4. The layered water injection string according to claim 1, characterized in that: The first connection terminal includes a first fixing plate, a first power-carrying coil and a first connecting portion. The first power-carrying coil is fixed on the first fixing plate. The first connecting portion is electrically connected to the first power-carrying coil. The first power-carrying coil is used to be electrically connected to a cable.

5. The layered water injection string according to claim 4, characterized in that: The first fixing plate has a first water passage communicating with the interior of the conventional pipe.

6. The layered water injection string according to claim 1, characterized in that: The second connection terminal includes a second fixed disk, a second power-carrying coil and a second connection portion, the second power-carrying coil is fixed on the second fixed disk, the second connection portion is electrically connected to the second power-carrying coil, and the second power-carrying coil is used to be electrically connected to a cable.

7. The layered water injection string according to claim 6, characterized in that: The first fixing plate has a first water passage communicating with the interior of the conventional pipe.

8. The layered water injection string according to claim 1, characterized in that: Part of the first cable channel is disposed outside the conventional pipe.

9. The layered water injection string according to claim 1, characterized in that: The crossing pipe includes a first pipe section and a second pipe section, the first pipe section is sleeved in the conventional pipe, the first connecting terminal is arranged in the second pipe section, the first cable channel includes a first channel section and a second channel section connected to each other, the first channel section is arranged in the first pipe section, the second channel section is arranged in the second pipe section, and the opening area of ​​the first channel section is larger than the opening area of ​​the second channel section.

10. The layered water injection string according to any one of claims 1 to 3, characterized in that: The conventional pipe or the prefabricated pipe is provided with a drain port, and the stratified water injection pipe column also includes a differential pressure switch, which is installed at the drain port. The differential pressure switch includes a differential pressure tube body, a connecting seat and a switch member; the differential pressure tube body is provided with a second water passage; the connecting seat is a rotating body, which is connected to the inner wall of the differential pressure tube body along the circumference of the differential pressure tube body, dividing the second water passage into two sub-channels; the connecting seat is provided with a water passage running through the connecting seat, and the water passage connects the two divided sub-channels; the switch member is arranged at the front end of the connecting seat along the direction of water flow, and can reciprocate along the axial direction of the differential pressure tube body to abut or be spaced from the connecting seat, so that the water passage is disconnected or connected with the second water passage.

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