Composite back-insertion well cementation device for multilateral wellbore

Abstract

The invention belongs to the technical field of petroleum and natural gas resource development, particularly relates to a multilateral well hole composite back-insertion well cementation device, and aims to solve the problem that cement is left in a main well hole when a multilateral well hole is reinforced. The device comprises an upper joint, a lower joint, a sealing cylinder, a composite insertion pipe, a hollow rubber plug and a drill rod rubber plug for pushing the hollow rubber plug, the sealing cylinder is arranged between the upper connector and the lower connector, and the upper connector and the lower connector on the same pipe column are connected together. The composite intubation tube comprises an outer intubation tube and an inner intubation tube; the outer insertion pipe is inserted into the sealing cylinder, and the inner insertion pipe is inserted into the outer insertion pipe; the hollow rubber plug is installed in the lower connector. By means of the method, well cementation of the multilateral well and flushing of redundant cement on the overlapped section of the two multilateral well are completed through one-time drilling. And the cement is easier to wash before being solidified, and the overlapped section of the multilateral well bore is supported by complete mechanical support and cement support after well completion, so that the construction risk is lower, and the construction efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of oil and gas resource development, and specifically relates to a branch wellbore composite backfill cementing device. Background Technology

[0002] Branch well technology refers to drilling two or more branch wells (secondary wells) into the oil and gas reservoir from the bottom of a main wellbore, and even drilling tertiary sub-wells from the secondary wells. The main wellbore can be a vertical well, a directional well, or a horizontal well. Branch wells can be directional wells, horizontal wells, or wave-shaped branch wells. Multi-branch wells can exploit multiple oil and gas layers within a single main wellbore, achieving multi-target and three-dimensional production from a single well.

[0003] Currently, there are two common methods for cementing branch wells on the market. The first method is "external positioning + internal isolation sleeve". Positioning and orientation can be achieved through the positioning mechanism on the outside of the overlapping section suspension tool. The tool has an isolation sleeve inside, which seals the prefabricated window for entering the main wellbore, making the branch wellbore a complete pressure system. It is possible to run the branch wellbore casing and cement cement in one trip. However, the cement will return from outside the suspension device, and some cement will inevitably remain in the main wellbore. To flush the excess cement in the main wellbore, it is necessary to pull out the drill string and run in a special tool again to retrieve the isolation sleeve and flush the main wellbore. Although the cementing efficiency is high, it still requires two or three trips to complete the flushing of the main wellbore. Moreover, if there is a lot of cement in the main wellbore, it may be difficult to enter the main wellbore in the second trip if the cement has solidified.

[0004] Another method is "milling the overlapping section". After the branch well is completed, the casing is directly run and cemented, which is no different from the construction method of conventional wells. No special positioning and orientation are required. However, in order to enter the main well, a milling tool needs to be run to mill out the overlapping section casing and directional tool together. The construction is more complicated. Moreover, after milling, the overlapping section of the branch well has no mechanical support, which has a great impact on the life of the branch well and the convenience of re-entry in the future. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, namely the issue of rapid cement removal from the main wellbore during branch well reinforcement, this invention provides a composite backfill cementing device for branch wells.

[0006] This application discloses a composite backfill cementing device for branched wellbores, which adopts the following technical solution:

[0007] A branch wellbore composite backfill cementing device includes an upper connector, a lower connector, a sealing cylinder, a composite insert pipe, a hollow rubber plug, and a drill pipe rubber plug for pushing the hollow rubber plug.

[0008] The sealing cylinder is arranged between the upper and lower connectors, connecting the upper and lower connectors on the same tubing column together.

[0009] The composite cannula includes an outer cannula and an inner cannula; the outer cannula is inserted into the sealing cylinder, and the inner cannula is inserted into the outer cannula; the hollow rubber plug is installed inside the lower connector.

[0010] By adopting the above technical solution, the lower connector is connected to the top of the uppermost casing in the branch wellbore. The upper connector is connected to a rotating sub, a pre-windowed casing sub, and a pre-windowed hanger. The branch wellbore completion casing is delivered into the well by the drill string. The drill string is connected to an MWD or directional connector. Before drilling, the angle difference between the window of the pre-windowed casing sub and the positioning key of the MWD or directional connector is measured. Before the pre-windowed casing sub enters the open hole, the suspended weight during lifting and lowering is measured. The pre-windowed casing is measured and calculated using an MWD or gyroscope. The orientation of the short section window is determined by the presence of a rotating short section above the joint of the cementing sealing tube. Therefore, the rotating cementing sealing tube and the casing below it will not rotate. After positioning, the short section is slowly lowered into the well. Once the hard shaft inside the pre-opened window casing enters the main wellbore and re-enters the inner hole of the directional tool, the section is lowered until the suspended weight is reduced. The short section of the pre-opened window casing is further aligned using the hard shaft. The pump is started and pressurized, indicating that the hard shaft is in place. The pump is then started to set the pre-opened window hanger. After successful setting and sealing verification, the pump is started until the pre-opened window hanger is hydraulically released. The setting tool and hard shaft are then retrieved and inserted. The inner tube is connected to the bottom of the drill pipe and is fed into the well using the drill pipe. Before the composite tube enters the pre-opened window hanger, the lifting and lowering weight is measured to reduce the lowering speed until the composite tube is inserted into the sealing cylinder. Wait for the composite tube to be installed in place. An increase in the lifting weight indicates that it is in place. Press down 10t to perform circulating cementing. After the cementing cement is used up, release the drill pipe rubber plug in the cement head. After the drill pipe rubber plug enters the hollow rubber plug and combines with the hollow rubber plug, continue to push the hollow rubber plug so that the hollow rubber plug and the drill pipe rubber plug are disengaged from the lower joint. Continue to push the composite rubber plug to replace the cement to the pressure ring and press it. The cementing cement is completely pushed out of the casing, sealing the branch well casing. The cement return height is generally higher than the positioning hanger. After cementing is completed, the tubing string is pulled up, the locking ring secures the outer casing, and the inner casing is pulled out from inside the outer casing. The pump is then started to flush out excess cement from the pre-opened window casing. The inner casing is then pulled up into the pre-opened window hanger and re-inserted into the main wellbore and re-entering the directional control. Cement that has entered the main wellbore is flushed out. This completes the cementing of the branch wellbore.

[0011] Optionally, the external insertion tube is provided with insertion tube scissors, the ends of which penetrate the outer wall of the internal insertion tube.

[0012] Optionally, the portion of the inner tube inserted into the outer tube is reduced in diameter, an outer stepped surface is formed on the inner wall of the outer tube, and an inner protruding ring is formed on the outer wall of the inner tube inserted into the outer tube; when the outer tube is connected to the inner tube, the inner protruding ring contacts the outer stepped surface.

[0013] Optionally, an upper retaining ring is provided protruding from the inner wall of the upper connector;

[0014] The outer wall of the external insertion tube has a groove, and a locking ring is fitted on the external insertion tube. The locking ring is fitted at the groove of the external insertion tube and is arranged between the upper retaining ring and the sealing cylinder. The outer diameter of the locking ring is larger than the inner diameter of the upper retaining ring and the inner diameter of the sealing cylinder. Moreover, the inner surface of the locking ring facing the upper connector away from the sealing cylinder is a slope, and the thickness of the inner ring is smaller than the thickness of the outer ring.

[0015] Optionally, a sealing step surface is provided on the inner wall of the sealing cylinder, and an adhesive tube is provided on the sealing step surface. The adhesive tube is embedded in the sealing step surface and fixedly connected to the sealing cylinder; when the outer tube is inserted into the sealing cylinder, the adhesive tube is sleeved on the outer tube.

[0016] Optionally, a lower adhesive tube is provided on the sealing step surface, and the lower adhesive tube is also embedded in the sealing step surface and fixedly connected to the sealing tube;

[0017] A spacer sleeve is installed between the upper and lower glue cylinders. The spacer sleeve contacts the upper and lower glue cylinders and is arranged on the sealing step surface. It is also fixedly connected to the sealing cylinder. The inner diameters of the upper glue cylinder, lower glue cylinder, and spacer sleeve are the same.

[0018] When the upper and lower glue tubes are arranged in the sealed cylinder, the upper glue tube is arranged outside the lower glue tube.

[0019] Optionally, a pressure cap is installed at the end of the sealing cylinder to tighten the upper and lower rubber cylinders;

[0020] The pressure cap includes a horizontal tube and a vertical ring, with the horizontal tube and the vertical ring fixedly connected, and the vertical ring arranged on the outer side of the end of the horizontal tube;

[0021] The horizontal tube is inserted into the sealing cylinder and fixedly connected to the sealing step surface opened on the sealing cylinder. The inner diameter of the horizontal tube is the same as the inner diameter of the upper glue cylinder, and the horizontal tube is in contact with the upper glue cylinder. The vertical ring is in contact with the end face of the sealing cylinder, and the outer ring surface of the vertical ring is in contact with the inner wall of the upper connector.

[0022] Optionally, multiple fixing blocks are installed on the outside of the hollow rubber stopper, and rubber stopper cutters are inserted through the fixing blocks to connect the fixing blocks to the hollow rubber stopper.

[0023] Optionally, a lower step surface is provided on the inner wall of the lower connector, and when the hollow rubber plug is installed on the lower connector, the fixing block contacts the lower step surface.

[0024] The beneficial effects of this invention are:

[0025] (1) The tool is highly adaptable and can be used in vertical wells, directional wells and horizontal wells. It is simple and reliable to operate.

[0026] (2) The tool adopts an inner and outer composite insertion structure, and the inner and outer insertion tubes can be separated. The outer insertion tube remains in the branch wellbore, while the inner insertion tube can enter the main wellbore through the prefabricated window of the overlapping section casing. This allows for one-trip drilling and cementing and flushing of the overlapping section of two branch wellbores, resulting in higher construction efficiency and more reliable operation.

[0027] (3) The sealing cylinder adopts an embedded double-group rubber cylinder combination structure, which has better sealing performance and is not easily washed away.

[0028] (4) The fixing block for fixing the hollow rubber plug adopts a split design. After the hollow rubber plug is pushed away, the fixing block can fall off to the top of the drill rod rubber plug. The fixing block is made of aluminum, which is easy to grind and mill.

[0029] (5) All tools adopt mature structures, resulting in low construction risk and high success rate. Attached Figure Description

[0030] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0031] Figure 1 This is a schematic diagram showing that the drill pipe plug is not inserted into the inner tube in this embodiment;

[0032] Figure 2 This is a schematic diagram of the drill pipe plug inserted into the inner tube in this embodiment;

[0033] Figure 3 This is a schematic diagram of the upper connector in this embodiment;

[0034] Figure 4 This is a schematic diagram of the lower connector in this embodiment.

[0035] Explanation of reference numerals in the attached diagram: 1. Upper connector; 11. Upper retaining ring; 2. Lower connector; 21. Lower stepped surface; 3. Sealing cylinder; 31. Sealing stepped surface; 32. Upper rubber cylinder; 33. Lower rubber cylinder; 34. Spacer ring sleeve; 35. Pressure cap; 351. Horizontal tube; 352. Vertical ring; 4. Composite insertion tube; 41. Outer insertion tube; 411. Groove; 412. Outer stepped surface; 42. Inner insertion tube; 421. Insertion tube shear pin; 422. Inner convex ring; 43. Locking ring; 5. Hollow rubber plug; 51. Fixing block; 52. Rubber plug shear pin; 6. Drill rod rubber plug. Detailed Implementation

[0036] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] This invention provides a composite cementing device for branched wellbore, with reference to... Figure 1 , Figure 2 The branch wellbore composite backfill cementing device includes an upper connector 1, a lower connector 2, a sealing cylinder 3, a composite insert pipe 4, a hollow rubber plug 5, and a drill pipe rubber plug 6 that pushes the hollow rubber plug 5.

[0039] Reference Figure 2 , Figure 3 The lower connector 2 has a reduced diameter at its lower opening, while the upper connector 1 has an expanded diameter at its upper opening. An upper retaining ring 11 protrudes from the inner wall of the upper connector 1. A lower stepped surface 21 is formed on the upper outer wall of the lower connector 2. When the tubing columns are connected, the lower connector 2 of one tubing column is inserted into the upper connector 1 of another tubing column. The upper opening of the upper connector 1 is inserted into the lower opening of the lower connector 2. When the upper connector 1 and lower connector 2 are connected, the lower opening of the lower connector 2 is inserted into the upper opening of the upper connector 1.

[0040] A sealing cylinder 3 is positioned between the upper connector 1 and the lower connector 2, connecting the two connectors on the same tubing column. One end of the sealing cylinder 3 is fitted onto one end of the upper connector 1 and threadedly connected to it. The other end of the sealing cylinder 3 is inserted into one end of the lower connector 2 and threadedly connected to it. When the sealing cylinder 3 is connected to the upper connector 1 and the lower connector 2, a sealing treatment is performed at the connection point, and the outer diameter is adjusted to ensure a smooth transition of the outer wall when the sealing cylinder 3 is connected to the upper connector 1 and the lower connector 2. When the sealing cylinder 3 connects the upper connector 1 and the lower connector 2, pins are inserted through the upper connector 1 and the lower connector 2 to reinforce the connection. When the sealing cylinder 3 is connected to the upper connector 1, there is a gap between the end of the sealing cylinder 3 and the upper retaining ring 11 of the upper connector 1.

[0041] Reference Figure 2 , Figure 3 , Figure 4 The composite cannula 4 includes an external cannula 41 and an internal cannula 42.

[0042] The outer tube 41 is inserted into the sealing cylinder 3, with its outer wall in contact with the inner wall of the sealing cylinder 3, and a gap exists between the outer wall of the outer tube 41 and the inner ring surface of the upper retaining ring 11. A groove 411 is formed on the outer wall of the outer tube 41, and a locking ring 43 is fitted onto the outer tube 41. The locking ring 43 is positioned at the groove 411 of the outer tube 41 and is arranged between the upper retaining ring 11 and the sealing cylinder 3. The locking ring 43 is an annular ring with an opening, and its diameter can be changed by circumferential compression. The outer diameter of the locking ring 43 is larger than the inner diameter of the upper retaining ring 11 and the inner diameter of the sealing cylinder 3, and the inner surface of the locking ring 43 facing the upper connector 1 away from the sealing cylinder 3 is inclined, and the thickness of the inner ring is smaller than the thickness of the outer ring. When the external insertion tube 41 is inserted into the sealing cylinder 3, the end of the external insertion tube 41 first contacts the locking ring 43, pushing the locking ring 43 towards the sealing cylinder 3. The locking ring 43 is blocked by the sealing cylinder 3, and under the action of the inclined surface on the locking ring 43, the external insertion tube 41 opens the locking ring 43. As the external insertion tube 41 is inserted, the locking ring 43 changes its position on the external insertion tube 41 along the length direction of the external insertion tube 41 until the external insertion tube 41 stops being inserted, and then the locking ring 43 is arranged in the groove 411.

[0043] An inner cannula 42 is inserted into an outer cannula 41, with the portion of the inner cannula 42 inserted into the outer cannula 41 having a reduced diameter. A cannula shear pin 421 is inserted through the outer cannula 41, with the end of the shear pin 421 penetrating the outer wall of the inner cannula 42, connecting the inner cannula 42 and the outer cannula 41 together. An outer stepped surface 412 is formed on the inner wall of the outer cannula 41, and an inner protruding ring 422 protrudes from the outer wall where the inner cannula 42 is inserted. When the outer cannula 41 and the inner cannula 42 are connected, the inner protruding ring 422 contacts the outer stepped surface 412, limiting the movement of the inner cannula 42. A seal is formed between the inner cannula 42 and the outer cannula 41. After the cannula shear pin 421 is cut, the inner cannula 42 can be withdrawn from the outer cannula 41.

[0044] To improve the sealing effect between the external insertion tube 41 and the sealing cylinder 3 and prevent leakage between them, a sealing step surface 31 is provided on the inner wall of the sealing cylinder 3. This creates a gap between the external insertion tube 41 and the sealing cylinder 3 at the sealing step surface 31 when the external insertion tube 41 is inserted into the sealing cylinder 3. An adhesive applicator 32 is provided on the sealing step surface 31 and is embedded in it, thus fixing it to the sealing cylinder 3. When the external insertion tube 41 is inserted into the sealing cylinder 3, the adhesive applicator 32 is fitted onto the external insertion tube 41, filling and sealing the gap between the external insertion tube 41 and the inner wall of the sealing cylinder 3, thereby improving the sealing effect between them and preventing leakage. To prevent the outer tube 41 from dragging and deforming the upper adhesive tube 32 when it is inserted into the sealing cylinder 3, and to further improve the sealing effect between the outer tube 41 and the sealing cylinder 3, a lower adhesive tube 33 is provided on the sealing step surface 31. The lower adhesive tube 33 is also embedded in the sealing step surface 31 and fixedly connected to the sealing cylinder 3. By providing the upper adhesive tube 32 and the lower adhesive tube 33, the sealing range is increased, and the sealing effect between the outer tube 41 and the sealing cylinder 3 is further improved. There is a gap between the upper glue cylinder 32 and the lower glue cylinder 33, and a spacer ring 34 is installed between them. The spacer ring 34 contacts the upper glue cylinder 32 and the lower glue cylinder 33, is arranged on the sealing step surface 31, and is fixedly connected to the sealing cylinder 3. The spacer ring 34 is made of metal and is not easily deformed. It provides protection and support for the upper glue cylinder 32 and the lower glue cylinder 33 on both sides, improving the sealing effect between the sealing cylinder 3 and the outer insertion tube 41 while preventing the upper glue cylinder 32 and the lower glue cylinder 33 from coming out when the outer insertion tube 41 is inserted. The inner diameters of the upper glue cylinder 32, the lower glue cylinder 33, and the spacer ring 34 are the same. When the upper glue cylinder 32 and the lower glue cylinder 33 are arranged in the sealing cylinder 3, the upper glue cylinder 32 is arranged outside the lower glue cylinder 33.

[0045] To further reinforce the installation of the upper and lower adhesive sleeves 32 and 33, a pressure cap 35 is installed at the end of the sealing cylinder 3 to tighten the upper and lower adhesive sleeves 32 and 33. The pressure cap 35 includes a horizontal tube 351 and a vertical ring 352. The horizontal tube 351 is fixedly connected to the vertical ring 352, which is located on the outer side of the end of the horizontal tube 351. The horizontal tube 351 is inserted into the sealing cylinder 3 and threadedly connected to the sealing step surface 31 on the sealing cylinder 3, connecting the pressure cap 35 to the sealing cylinder 3. The inner diameter of the horizontal tube 351 is the same as the inner diameter of the upper adhesive sleeve 32. The horizontal tube 351 contacts the upper adhesive sleeve 32, blocking and restricting it, thus increasing the stability of the upper adhesive sleeve 32 installation. The vertical ring 352 contacts the end face of the sealing cylinder 3, and the outer ring surface of the vertical ring 352 contacts the inner wall of the upper connector 1.

[0046] Hollow rubber plug 5 is installed inside the lower connector 2, and multiple fixing blocks 51 are installed on the outside of hollow rubber plug 5. In this embodiment, three fixing blocks 51 are provided. Rubber plug cutter pins 52 are inserted through the fixing blocks 51, and the rubber plug cutter pins 52 connect the fixing blocks 51 and hollow rubber plug 5 together. The fixing blocks 51 are aluminum blocks, which are easy to grind and mill.

[0047] When the hollow rubber plug 5 contacts the inner wall of the lower connector 2, the hollow rubber plug 5 and the lower connector 2 are interference-fitted, allowing the hollow rubber plug 5 to be stably positioned on the lower connector 2 when not subjected to thrust. Furthermore, a lower stepped surface 21 is provided on the inner wall of the lower connector 2. When the hollow rubber plug 5 is installed on the lower connector 2, the fixing block 51 contacts the lower stepped surface 21, allowing the installation position of the hollow rubber plug 5 to be positioned by the cooperation of the fixing block 51 and the upper and lower stepped surfaces 21 of the lower connector 2. When the rubber plug shear pin 52 is cut, the hollow rubber plug 5, without the constraint of a steel body, can pass through the inner hole of the lower connector 2, and the fixing block 51 simultaneously falls off, without causing a reduction in diameter.

[0048] A drill rod plug 6 is inserted into the inner tube 42, and the drill rod plug 6 is inserted into the hollow plug 5.

[0049] In this embodiment, the method of using the branch wellbore composite backfill cementing device is as follows: The lower rubber sleeve 33, spacer ring 34, and upper rubber sleeve 32 are inserted into the sealing sleeve 3 in sequence. Then, the pressure cap 35 is screwed on to complete the assembly of the sealing sleeve 3. The locking ring 43 is then installed into the upper connector 1. After the assembled sleeve is fitted with a sealing ring, it is connected to the upper connector 1. Then, the three fixing blocks 51 are connected to the hollow rubber plug 5 using rubber plug shear pins 52, and then inserted together into the lower connector 2 to complete the assembly of the hollow rubber plug 5. After installing the sealing ring in the sealing ring groove at the lower end of the sealing sleeve 3, it is connected to the hollow rubber plug 5. Finally, the inner insertion tube 42 and the outer insertion tube 41 are connected and assembled into the composite insertion tube 4.

[0050] Connect the lower connector 2 to the top of the uppermost casing in the branch wellbore. Connect the upper connector 1 to the rotating sub, the pre-windowed casing sub, and the pre-windowed hanger. The branch well completion casing is delivered into the well by the drill string. Connect the MWD or directional connector to the drill string. Before running the drill string, measure the angle difference between the window of the pre-windowed casing sub and the positioning key of the MWD or directional connector. Before the pre-windowed casing sub enters the open hole, measure the lifting and lowering weight. Measure and calculate the orientation of the window of the pre-windowed casing sub using the MWD or gyroscope. Rotate the tubing string to open the pre-windowed section. The casing short section window is facing away from the window position. Because there is a rotating short section above the cementing seal tube joint, the rotating cementing seal tube and the casing below it will not rotate. After positioning, it is slowly lowered into the well. After the hard shaft in the pre-opened window casing enters the main wellbore and re-enters the inner hole of the directional tool, it continues to be lowered until the suspended weight is reduced. The pre-opened window casing short section is further aligned by the hard shaft. The pump starts and pressurizes, indicating that the hard shaft is in place. The pump continues to start to set the pre-opened window hanger. After successful setting and sealing, the pump continues to start until the pre-opened window hanger is hydraulically released. The setting tool and hard shaft are then retrieved and sent in.

[0051] The inner tube 42 is connected to the bottom of the drill pipe and is fed into the well using the drill pipe. Before the composite tube 4 enters the pre-opened window hanger, the suspended weight is measured by lifting and lowering to reduce the lowering speed until the composite tube 4 is inserted into the sealing cylinder 3. The locking ring 43 enters the groove 411 on the outside of the outer tube 41 and locks the outer tube 41. The suspended weight is slowly increased by lifting, indicating that the composite tube 4 has reached the correct position. The pressure is lowered by 10t for circulating cementing. After the cementing cement is applied, the drill pipe rubber plug 6 in the cement head is released. After the drill pipe rubber plug 6 enters the hollow rubber plug 5 and combines with the hollow rubber plug 5, the pressure is increased to shear the rubber plug shear pin 52 on the hollow rubber plug 5. The hollow rubber plug 5 is then pushed to disengage the hollow rubber plug 5 and the drill pipe rubber plug 6 from the lower connector 2. The composite rubber plug is pushed to replace the cement and press against the pressure ring. The cementing cement is completely pushed out of the casing, sealing the branch well casing. The cement return height is generally higher than the positioning hanger.

[0052] After reinforcement is completed, the tubing string is lifted, the locking ring 43 locks the outer insertion pipe 41, the tubing string is lifted to pull the inner insertion pipe 42 out from the outer insertion pipe 41, the pump is turned on to flush out the excess cement in the pre-opened window casing, the inner insertion pipe 42 is lifted into the pre-opened window hanger, and then the inner insertion pipe 42 is lowered back in so that it enters the main wellbore and re-enters the directional device, flushing out the cement that has entered the main wellbore. Thus, the cementing construction of the branch wellbore is completed.

[0053] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0054] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A composite backfill cementing device for branch wellbores, characterized in that: It includes an upper connector (1), a lower connector (2), a sealing cylinder (3), a composite insert (4), a hollow rubber plug (5), and a drill rod rubber plug (6) that pushes the hollow rubber plug (5); The sealing cylinder (3) is arranged between the upper connector (1) and the lower connector (2) to connect the upper connector (1) and the lower connector (2) on the same pipe column together; The composite cannula (4) includes an outer cannula (41) and an inner cannula (42); the outer cannula (41) is inserted into the sealing cylinder (3), and the inner cannula (42) is inserted into the outer cannula (41); the hollow rubber plug (5) is installed inside the lower connector (2).

2. The branch wellbore composite backfill cementing device according to claim 1, characterized in that: The external insertion tube (41) is provided with insertion tube clips (421), and the end of the insertion tube clips (421) is inserted into the outer wall of the internal insertion tube (42).

3. The branch wellbore composite backfill cementing device according to claim 1, characterized in that: The portion of the inner tube (42) inserted into the outer tube (41) is reduced in diameter. An outer stepped surface (412) is provided on the inner wall of the outer tube (41), and an inner protruding ring (422) is provided on the outer wall of the inner tube (42) inserted into the outer tube (41). When the outer tube (41) is connected to the inner tube (42), the inner protruding ring (422) contacts the outer stepped surface (412).

4. The branch wellbore composite backfill cementing device according to claim 1, characterized in that: An upper retaining ring (11) is provided protruding from the inner wall of the upper connector (1); The outer wall of the external insertion tube (41) is provided with a groove (411), and a locking ring (43) is fitted on the external insertion tube (41). The locking ring (43) is fitted at the groove (411) of the external insertion tube (41). The locking ring (43) is arranged between the upper retaining ring (11) and the sealing cylinder (3). The outer diameter of the locking ring (43) is larger than the inner diameter of the upper retaining ring (11) and the inner diameter of the sealing cylinder (3). Moreover, the inner surface of the locking ring (43) facing the upper connector (1) away from the sealing cylinder (3) is a slope, and the thickness of the inner ring is smaller than the thickness of the outer ring.

5. The branch wellbore composite backfill cementing device according to claim 4, characterized in that: The inner wall of the sealing cylinder (3) is provided with a sealing step surface (31), and an adhesive tube (32) is provided on the sealing step surface (31). The adhesive tube (32) is embedded in the sealing step surface (31) and fixedly connected to the sealing cylinder (3). When the external insertion tube (41) is inserted into the sealing cylinder (3), the adhesive tube (32) is sleeved on the external insertion tube (41).

6. The branch wellbore composite backfill cementing device according to claim 5, characterized in that: A lower rubber cylinder (33) is provided on the sealing step surface (31), and the lower rubber cylinder (33) is also embedded in the sealing step surface (31) and fixedly connected to the sealing cylinder (3); A spacer sleeve (34) is installed between the upper glue cylinder (32) and the lower glue cylinder (33). The spacer sleeve (34) contacts the upper glue cylinder (32) and the lower glue cylinder (33). The spacer sleeve (34) is arranged on the sealing step surface (31) and is fixedly connected to the sealing cylinder (3). The inner diameters of the upper glue cylinder (32), the lower glue cylinder (33) and the spacer sleeve (34) are the same. When the upper glue cylinder (32) and the lower glue cylinder (33) are arranged in the sealing cylinder (3), the upper glue cylinder (32) is arranged outside the lower glue cylinder (33).

7. The branch wellbore composite backfill cementing device according to claim 6, characterized in that: A pressure cap (35) is installed at the end of the sealing cylinder (3) to tighten the upper rubber cylinder (32) and the lower rubber cylinder (33); The pressure cap (35) includes a horizontal tube (351) and a vertical ring (352), the horizontal tube (351) and the vertical ring (352) are fixedly connected, and the vertical ring (352) is arranged on the outer side of the end of the horizontal tube (351); The horizontal tube (351) is inserted into the sealing cylinder (3) and fixedly connected to the sealing step surface (31) opened on the sealing cylinder (3). The inner diameter of the horizontal tube (351) is the same as the inner diameter of the upper glue cylinder (32). The horizontal tube (351) is in contact with the upper glue cylinder (32). The vertical ring (352) is in contact with the end face of the sealing cylinder (3), and the outer ring surface of the vertical ring (352) is in contact with the inner wall of the upper connector (1).

8. The branch wellbore composite backfill cementing device according to claim 1, characterized in that: Multiple fixing blocks (51) are installed on the outside of the hollow rubber stopper (5). A rubber stopper cutter (52) is inserted through the fixing block (51) and connects the fixing block (51) to the hollow rubber stopper (5).

9. The branch wellbore composite backfill cementing device according to claim 8, characterized in that: The inner wall of the lower connector (2) has a lower step surface (21). When the hollow rubber plug (5) is installed on the lower connector (2), the fixing block (51) contacts the lower step surface (21).

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