Downhole string based on integration of oil production and well flushing

Abstract

The application discloses a downhole pipe string based on oil production and well washing integration, which comprises a plurality of oil pipes, a baffle ring and a screen pipe, the plurality of oil pipes are connected in series to form a pipe string, and the pipe string has a double circulation channel; the baffle ring and the screen pipe are respectively sleeved on the surface of the oil pipe, one end of the baffle ring close to the screen pipe is provided with a flow channel, and the other end of the baffle ring is provided with a one-way valve; the oil pipe is provided with a valve penetrating through the inside of the oil pipe, and the surface of the oil pipe is further sleeved with an outer protection pipe used in cooperation with the screen pipe and the baffle ring; the screen pipe, the baffle ring, the one-way valve, the valve and the oil pipe constitute an oil production circulation channel; the tail end of the pipe string is provided with a guide shoe, and the oil pipe and the guide shoe constitute a well washing circulation channel; the integrated pipe string not only eliminates the operation of multiple times of well washing pipe string lifting and lowering, but also optimizes the setting process of the packer through the integrated design.

Description

Technical Field

[0001] This invention relates to the field of petroleum engineering technology applications, specifically to a downhole tubing string based on integrated oil production and well washing. Background Technology

[0002] During the long-term production process of oil wells, various impurities such as wax, colloids, asphalt, sand, silt, and corrosion products gradually accumulate inside the wellbore and tubing. These deposits gradually reduce the cross-sectional area for medium flow and may even cause local blockages, directly blocking the normal flow path of crude oil. Well washing is an indispensable basic guarantee operation in the oil extraction process. Through regular well washing, the flushing and dissolving effects of the washing medium can thoroughly remove various blockages in the wellbore and tubing, restore and maintain the effective flow space of the wellbore and tubing, and ensure that crude oil and oil-gas mixtures can flow smoothly from the oil layer to the wellhead, avoiding reduced or even stopped oil well production due to wellbore blockage.

[0003] However, traditional well washing operations require all existing production tubing to be brought to the surface, the wear of the tubing to be inspected, and then a special well washing tubing to be lowered. Well washing medium is then injected into the well washing tubing using a pump truck, and the medium is circulated repeatedly in the annular space between the tubing and casing using either forward or reverse circulation to remove impurities from the tubing.

[0004] After well washing is completed, the well washing tubing string must be pulled out again, and then the production tubing string must be run in to complete wellhead sealing and pressure testing, and finally restore normal oil well production.

[0005] The overall process is cumbersome and highly dependent on manpower and equipment. Moreover, the entire process requires a large amount of manpower and resources, resulting in high costs, long cycles, and impacting the production of the entire oil well.

[0006] Based on the above problems, there is an urgent need for a new type of downhole tubing that can automatically switch between well washing and oil production conditions, in order to shorten the well washing cycle, reduce well washing costs, and avoid repeated tripping of the well washing tubing, which would affect operational efficiency. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a downhole tubing string that integrates oil production and well washing. This integrated tubing string not only eliminates the need for multiple tripping and running of the well washing tubing string, but also optimizes the packer setting process through its integrated design.

[0008] The technical solution of the present invention is: a downhole tubing string based on integrated oil production and well washing, comprising multiple tubing, retaining rings and screen pipes, wherein the multiple tubing are connected in series to form a tubing string, and the tubing string has a dual circulation channel; The retaining ring and screen tube are respectively sleeved on the surface of the oil pipe, and the end of the retaining ring near the screen tube is provided with a flow channel, and the other end of the retaining ring is provided with a one-way valve; the oil pipe is provided with a valve that penetrates the inside of the oil pipe, and the surface of the oil pipe is also sleeved with an outer protective tube for use with the screen tube and retaining ring. The screen tube, retaining ring, one-way valve, valve and oil pipe constitute an oil production circulation channel; The end of the tubing string is equipped with a guide shoe, and the tubing and the guide shoe form a well-washing circulation channel.

[0009] Furthermore, it also includes couplings that connect the oil pipes to each other.

[0010] Furthermore, it also includes a packer disposed between the two oil pipes, one end of which is connected to the outer protective pipe, and the other end of which is connected to the screen pipe or the outer protective pipe.

[0011] Furthermore, there is a gap between the outer protective tube and the oil pipe, one end of the outer protective tube is connected to the screen pipe, and the other end of the outer protective tube is connected to the packer, forming an annulus for crude oil to pass through.

[0012] Furthermore, the valve is located in the annulus, and multiple valves are provided.

[0013] Furthermore, one end of the screen tube is connected to the packer, and the other end of the screen tube is connected to the outer protective tube.

[0014] Furthermore, the one-way valve is fixed to the retaining ring by bolts. The one-way valve is a swing one-way valve and includes: a spring seat fixed to the retaining ring by bolts and a baffle plate rotatably connected to the spring seat. The spring seat is connected to a torsion spring by a positioning pin. The upper end face of the baffle plate abuts against the torsion spring, and the lower end face of the baffle plate blocks the flow channel.

[0015] Furthermore, the one-way valve is fixed to the retaining ring by bolts. The one-way valve is a spring one-way valve and includes: an end cap fixed to the retaining ring by bolts, a valve seat connected to the end cap, and a spring-shaped member disposed in the valve seat. One end of the valve seat is provided with a first channel for use with the flow channel, and the end of the valve seat connected to the end cover is provided with a second channel; When the elastic element abuts against the first channel, the flow channel, the first channel, and the second channel cannot communicate. When the elastic element is separated from the first channel, the flow channel, the first channel, and the second channel are connected.

[0016] Furthermore, the outer protective tube covers the retaining ring to form a sealed annular space.

[0017] The beneficial technical effects of this invention are: 1. The well-washing fluid is injected downwards from the wellhead through the tubing, flows through the internal channels of the tubing, and is finally discharged from the guide shoe. It enters the annulus between the well wall and the outer casing, and then returns to the wellhead along the annulus to complete the well-washing cycle. Because of the presence of the check valve, it remains closed during the forward flow of the well-washing fluid. The pressure of the well-washing fluid acts on the reverse side of the check valve, causing it to close and blocking the flow of the well-washing fluid from the screen pipe into the well wall channel, thus preventing contamination of the oil reservoir. This also eliminates the high-pressure impact of the well-washing fluid on the valve, protecting its structure. Furthermore, it ensures that there is no pressure leakage within the tubing.

[0018] After the well-washing fluid enters the annulus of the well wall through the guide shoe, it flows upward along the annulus, carrying impurities from the bottom of the well back to the wellhead, thus achieving efficient well washing.

[0019] 2. Crude oil enters the annulus between the outer casing and the tubing from the reservoir through the screen pipe. After passing through the retaining ring flow channel, it flows through the check valve, and then the flow is controlled by the valve before entering the tubing. Finally, it is transported upward along the tubing to the wellhead.

[0020] During the forward flow of crude oil, the check valve is in the open position. The crude oil pressure acts on the forward side of the check valve, opening it and thus opening the flow path.

[0021] When oil production is suspended or pressure fluctuations occur, the reverse flow of crude oil will trigger the one-way valve to close, effectively preventing crude oil backflow and avoiding reservoir pressure loss and valve damage.

[0022] 3. The one-way valve located at the retaining ring can form a closed cavity inside the oil pipe, eliminating pressure leakage and allowing direct transmission of setting pressure to drive the packer's rubber sleeve to expand and set.

[0023] 4. Different check valves meet various working conditions: swing check valves and spring check valves are adapted to the fluid characteristics under different working conditions. The swing type has a sensitive response and low opening resistance, while the spring type has a reliable seal and strong impact resistance. Different check valves can be selected for different needs.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the present invention; Figure 3 This is a schematic diagram of the well-washing operation principle of the present invention; Figure 4 This is a schematic diagram of the oil production operation principle of the present invention; Figure 5 This is a schematic diagram of the connection between the one-way valve and the retaining ring of the present invention; Figure 6 This is a schematic diagram of the spring check valve of the present invention; Figure 7 This is a cross-sectional view of the spring check valve of the present invention; Figure 8 This is another embodiment of the structural diagram showing the connection between the one-way valve and the retaining ring of the present invention; Figure 9 This is a schematic diagram of the swing check valve of the present invention.

[0026] The attached figures are labeled as follows: 1. Oil pipe; 11. Valve; 2. Packer; 3. Outer protective pipe; 4. Screen pipe; 5. Guide shoe; 6. Retaining ring; 61. Check valve; 62. Spring check valve; 621. Valve seat; 622. End cap; 623. Second channel; 624. First channel; 625. Elastic element; 63. Flow channel; 64. Swing check valve; 641. Spring seat; 642. Baffle; 643. Locating pin; 644. Torsion spring. Detailed Implementation

[0027] In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0028] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate for the embodiments of this application described herein.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship described in the embodiments and shown in the accompanying drawings, or the orientation or positional relationship that the product of this invention is usually placed in during use. They are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0030] like Figure 1-9 As shown, the present invention specifically relates to a downhole tubing string based on integrated oil production and well washing, including multiple tubing 1, retaining ring 6 and screen pipe 4, the multiple tubing 1 connected in series to form a tubing string, the tubing string having a dual circulation channel; The retaining ring 6 and the screen tube 4 are respectively sleeved on the surface of the oil pipe 1, and the retaining ring 6 is provided with a flow channel 63 at one end near the screen tube 4, and a one-way valve 61 at the other end of the retaining ring 6; the oil pipe 1 is provided with a valve 11 that penetrates the inside of the oil pipe 1, and the surface of the oil pipe 1 is also sleeved with an outer protective tube 3 that works with the screen tube 4 and the retaining ring 6. The screen tube 4, the retaining ring 6, the one-way valve 61, the valve 11 and the oil pipe 1 constitute an oil production circulation channel; The end of the tubing string is provided with a guide shoe 5, and the tubing 1 and the guide shoe 5 form a well washing circulation channel.

[0031] It should be noted that, firstly, the tubing string is composed of multiple tubing 1s. The tubing string is lowered into the well and the well section is divided by the packer 2. The screen pipe 4 corresponds to the oil-producing layer. The one-way valves 61 are respectively arranged at the retaining rings 6 at the ends of the screen pipe 4 and are arranged coaxially with the valves 11.

[0032] Once the tubing reaches the designated position, high pressure is injected into tubing 1. The high pressure causes the rubber sleeve of packer 2 to expand, thereby achieving setting.

[0033] like Figure 2 and Figure 3 As shown, the end of the tubing string is equipped with a guide shoe 5. When the tubing string needs to be cleaned, the well cleaning fluid is injected from the inlet. The well cleaning fluid flows downward through the tubing 1. At this time, the one-way valve 61 is closed, which blocks the channel of the screen pipe 4. The well cleaning fluid continues to flow in the tubing 1 and is discharged from the guide shoe 5 and then returns to the wellhead along the annulus to complete the well cleaning cycle.

[0034] like Figure 2 and Figure 4 As shown, during oil production operations, crude oil enters the annulus between tubing 1 and outer protective pipe 3 from the reservoir through screen pipe 4. The pressure drives check valve 61 to open, and the crude oil enters tubing 1 after being controlled by check valve 61 and valve 11, and is transported upward along tubing 1 to the wellhead. When oil production is suspended, check valve 61 automatically closes to prevent backflow.

[0035] It also includes couplings that connect the oil pipes 1 to each other.

[0036] It should be noted that, under normal circumstances, the oil pipes 1 are connected by couplings to ensure both stability and sealing. This configuration applies when the oil density and gas content within the oil layer are uniform.

[0037] Additionally, the tubing sections 1 in the downhole without oil are connected by couplings. Similarly, the outer surface of tubing 1 is covered by an outer protective tube 3.

[0038] It also includes a packer 2 disposed between the two oil pipes 1, one end of the packer 2 being connected to the outer protective pipe 3, and the other end of the packer 2 being connected to the screen pipe 4 or the outer protective pipe 3.

[0039] It should be noted that if the oil layer is complex and each section of oil is slightly different, a packer 2 is needed to completely isolate them from the wellbore section to ensure the purity and stability of each section of oil. Similarly, the packer 2 blocks the annulus between the outer casing 3 and the wellbore while connecting the tubing 1.

[0040] In addition, since the tubing string is composed of multiple tubing 1, it will also be equipped with multiple outer protective tubes 3. The packer 2 not only serves to connect the tubing 1, but also serves to connect the outer protective tubes 3.

[0041] Similarly, when the tubing 1 is located in the oil-producing layer, the packer 2 can also connect the outer protective tube 3 and the screen tube 4. The packer 2 seals one end of the outer protective tube 3 so that crude oil enters the screen tube 4, the retaining ring 6 and the one-way valve 61 in sequence, and is in the annular state between the tubing 1 and the outer protective tube 3, and enters the tubing 1 through the valve 11 of the tubing 1.

[0042] There is a gap between the outer protective tube 3 and the oil pipe 1. One end of the outer protective tube 3 is connected to the screen pipe 4, and the other end of the outer protective tube 3 is connected to the packer 2, forming an annulus for crude oil to pass through.

[0043] One end of the outer protective tube 3 is connected to the retaining ring 6, and the other end of the outer protective tube 3 is sealed by the divider, so that a cavity is formed between the outer protective tube 3 and the oil pipe 1. This cavity is called the annulus. The valve 11 is located in this annulus. When crude oil enters the annulus, it enters the oil pipe 1 through the valve 11.

[0044] The valve 11 is located in the annulus, and there are multiple valves 11. By providing multiple sets of valves 11, the throughput efficiency of crude oil can be improved.

[0045] One end of the screen tube 4 is connected to the packer 2, and the other end of the screen tube 4 is connected to the outer protective tube 3.

[0046] By blocking the other end of the screen pipe 4 with the packer 2, crude oil can directly enter the retaining ring 6, the one-way valve 61, and the annulus between the outer protective pipe 3 and the oil pipe 1 under pressure through the screen pipe 4.

[0047] The one-way valve 61 is fixed to the retaining ring 6 by bolts. The one-way valve 61 is a swing one-way valve 64 and includes: a spring seat 641 fixed to the retaining ring 6 by bolts and a baffle 642 rotatably connected to the spring seat 641. The spring seat 641 is connected to a torsion spring 644 by a positioning pin 643. The upper end face of the baffle 642 abuts against the torsion spring 644, and the lower end face of the baffle 642 blocks the flow channel 63.

[0048] It should be noted that the one-way valve 61 is understood as a valve body that allows passage in one direction but not in the other. By setting up the one-way valve 61, not only can crude oil pass through during oil production, but also, when tubing cleaning is required, the reverse closed state of the one-way valve 61 prevents the washing fluid from flowing into the well wall channel from the screen pipe 4, avoiding contamination of the oil reservoir. It also eliminates the high-pressure impact of the washing fluid on valve 11, protecting the structure of valve 11. Furthermore, it ensures that there is no pressure leakage within the tubing 1.

[0049] Additionally, when the packer 2 needs to be set, the presence of the check valve 61 creates a closed space between the outer protective tube 3 and the oil pipe 1, eliminating pressure leakage and allowing the setting pressure to be directly transmitted to drive the rubber sleeve of the packer 2 to expand and set.

[0050] The following is a detailed description of the swing check valve 64 in the embodiment: like Figures 8-9 As shown, the swing check valve 64 includes a spring seat 641, a baffle 642, a torsion spring 644, a locating pin 643, and bolts. The baffle 642 is a movable component; pressure differential will self-drive the baffle 642 to flip open relative to the spring seat 641. When no pressure is applied, the baffle 642 will automatically close under the force of the torsion spring 644. The spring seat 641 is bolted to the retaining ring 6 to prevent misalignment of the check valve 61. The torsion spring 644 is fixed to the spring seat 641 by the locating pin 643. The longer section of the torsion spring 644 is positioned above the baffle 642, providing pressure to the baffle 642 and causing it to close automatically.

[0051] When the baffle 642 abuts against the flow channel 63, crude oil cannot pass through the flow channel 63; when the baffle 642 separates from the flow channel 63, crude oil can pass through the flow channel 63.

[0052] Under normal circumstances, the baffle 642 is always in contact with the retaining ring 6 due to the action of the torsion spring 644, thereby sealing the flow channel 63 of the retaining ring 6. When crude oil enters the flow channel 63 of the retaining ring 6 through the screen pipe 4, the pressure of the crude oil drives the baffle 642 to flip relative to the spring seat 641, thereby opening the flow channel 63 of the retaining ring 6. The crude oil then enters the annulus between the oil pipe 1 and the outer protective pipe 3 through the flow channel 63, and enters the oil pipe 1 through the valve 11.

[0053] When the pressure of the crude oil disappears, under the torsion of the torsion spring 644, the baffle 642 flips relative to the spring seat 641 and returns to its original position, thereby sealing the flow channel 63 of the retaining ring 6.

[0054] like Figures 5-7As shown, the one-way valve 61 is fixed to the retaining ring 6 by bolts. The one-way valve 61 is a spring one-way valve 62 and includes: an end cap 622 fixed to the retaining ring 6 by bolts, a valve seat 621 connected to the end cap 622, and a spring-shaped member disposed in the valve seat 621. One end of the valve seat 621 is provided with a first channel 624 that cooperates with the flow channel 63, and the end of the valve seat 621 connected to the end cover 622 is provided with a second channel 623. When the elastic element 625 abuts against the first channel 624, the flow channel 63, the first channel 624 and the second channel 623 cannot communicate; When the elastic element 625 is separated from the first channel 624, the flow channel 63, the first channel 624 and the second channel 623 are connected.

[0055] The function and principle of check valve 61 have been described in detail above, and the principle of one of the swing check valves 64 has also been described. Now, another spring check valve 62 is also provided. Its principle is the same as that of the swing check valve 64. Both use the pressure of crude oil to drive the valve core to move, thereby opening the flow channel 63. When the pressure of crude oil is lost, the flow channel 63 closes.

[0056] In the swing check valve 64, the valve core refers to the baffle 642, and in the spring check valve 62, it refers to the elastic element 625.

[0057] The spring check valve 62 is a self-operated differential pressure control type check valve 61. It relies on the cooperation of the fluid forward and reverse pressure difference and the return spring to achieve the function of forward conduction and reverse cut-off.

[0058] For example, reverse cutoff state: When the fluid flows from right to left, the fluid pressure pushes the valve core to move towards the valve seat 621, and the elastic element 625 is in the reset state. The sealing surface of the elastic element 625 and the valve seat 621 are tightly fitted, the flow channel 63 is completely blocked, and the fluid is prevented from flowing backward. The tight fit of the sealing surface ensures no leakage under high pressure and guarantees the pressure holding and backflow prevention requirements of the downhole working conditions.

[0059] For example, in a positive flow state: When fluid enters the first channel 624 of the end cap 622 from left to right, the fluid pressure acts on the end face of the elastic element 625, overcoming the preload of the elastic element 625 and pushing it to move towards the end cap 622. The elastic element 625 separates from the valve seat 621, the first channel 624 opens, and the fluid flows out through the gap between the elastic element 625 and the valve seat 621, achieving forward conduction. At the same time, the elastic element 625 is compressed, storing reset energy to prepare for reverse cutoff. The outer protective tube 3 covers the retaining ring 6 to form an annular state.

[0060] The above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and are not intended to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A downhole tubing string integrating oil production and well washing, characterized in that, It includes multiple oil pipes (1), a retaining ring (6) and a screen pipe (4), the multiple oil pipes (1) are connected in series to form a tubing string, and the tubing string has a double circulation channel; The retaining ring (6) and the screen tube (4) are respectively sleeved on the surface of the oil pipe (1), and the retaining ring (6) is provided with a flow channel (63) at one end near the screen tube (4), and a one-way valve (61) is provided at the other end of the retaining ring (6); the oil pipe (1) is provided with a valve (11) that penetrates the inside of the oil pipe (1), and the surface of the oil pipe (1) is also sleeved with an outer protective tube (3) for use with the screen tube (4) and the retaining ring (6). The screen tube (4), the retaining ring (6), the one-way valve (61), the valve (11) and the oil pipe (1) constitute an oil production circulation channel; The end of the tubing string is provided with a guide shoe (5), and the tubing (1) and the guide shoe (5) form a well washing circulation channel.

2. The downhole tubing string based on integrated oil production and well washing as described in claim 1, characterized in that, It also includes couplings that connect the oil pipes (1) to each other.

3. The downhole tubing string based on integrated oil production and well washing as described in claim 1, characterized in that, It also includes a packer (2) disposed between the two oil pipes (1), one end of the packer (2) being connected to the outer protective pipe (3), and the other end of the packer (2) being connected to the screen pipe (4) or the outer protective pipe (3).

4. The downhole tubing string based on integrated oil production and well washing as described in claim 3, characterized in that, There is a gap between the outer protective tube (3) and the oil pipe (1). One end of the outer protective tube (3) is connected to the screen pipe (4), and the other end of the outer protective tube (3) is connected to the packer (2), forming an annulus for crude oil to pass through.

5. The downhole tubing string based on integrated oil production and well washing as described in claim 4, characterized in that, The valve (11) is located in the annulus, and there are multiple valves (11).

6. The downhole tubing string based on integrated oil production and well washing as described in claim 3, characterized in that, One end of the screen tube (4) is connected to the packer (2), and the other end of the screen tube (4) is connected to the outer protective tube (3).

7. The downhole tubing string based on integrated oil production and well washing as described in claim 1, characterized in that, The one-way valve (61) is fixed to the retaining ring (6) by bolts. The one-way valve (61) is a swing one-way valve (64) and includes: a spring seat (641) fixed to the retaining ring (6) by bolts and a baffle (642) rotatably connected to the spring seat (641). The spring seat (641) is connected to a torsion spring (644) by a positioning pin (643). The upper end face of the baffle (642) abuts against the torsion spring (644), and the lower end face of the baffle (642) blocks the flow channel (63).

8. The downhole tubing string based on integrated oil production and well washing as described in claim 1, characterized in that, The one-way valve (61) is fixed to the retaining ring (6) by bolts. The one-way valve (61) is a spring one-way valve (62) and includes: an end cap (622) fixed to the retaining ring (6) by bolts, a valve seat (621) connected to the end cap (622), and a spring-shaped member disposed in the valve seat (621); One end of the valve seat (621) is provided with a first channel (624) for use with the flow channel (63), and the end of the valve seat (621) connected to the end cap (622) is provided with a second channel (623); When the elastic element (625) abuts against the first channel (624), the flow channel (63), the first channel (624) and the second channel (623) cannot communicate; When the elastic element (625) is separated from the first channel (624), the flow channel (63), the first channel (624) and the second channel (623) are connected.

9. The downhole tubing string based on integrated oil production and well washing as described in claim 1, characterized in that, The outer protective tube (3) covers the retaining ring (6) to form a sealed annular space.

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