A screen pipe

Abstract

The utility model belongs to oilfield machinery oil production downhole tool technical field, concretely relates to a screen pipe. The screen pipe includes the outer tube and the inner tube of setting in the outer tube, the outer tube is connected to the oil well pump through its upper pipe column, the annulus between the inner tube and the outer tube and the inner chamber lower port of the inner tube are closed to constitute the sand setting cylinder, and the port of the other constitutes the liquid inlet channel through the setting grid. The screen pipe provided by the utility model has the double functions of screen pipe and tail pipe, sets the liquid inlet path at the axial bottom end of the screen pipe, prolongs the flow path of the medicament when adding the medicament, the part of the tubing string below the well fluid level is all in the protection area of the medicament, eliminates the protection blind area of the tubing string, avoids the corrosion of the tubing string or the tool into the well, simultaneously, the process that the produced fluid enters the liquid inlet channel from the bottom end of the screen pipe and flows upwards into the inner cavity of the outer tube helps the sand particles to settle under the action of gravity, improves the sand liquid separation effect.

Description

Technical Field

[0001] This utility model belongs to the technical field of oilfield machinery downhole tools, specifically relating to a screen pipe. Background Technology

[0002] Currently, sand production in oil and gas wells has become a common problem in the development of loose sandstone oil and gas reservoirs in the mid-to-late stages of development. The main hazards of sand production include: reduced or halted production, accelerated wear on surface and downhole equipment, and damage to casing and well abandonment. Mechanical sand control measures, relying on mechanical sand screens or a combination of screens and gravel packing, are the main way to solve this problem and maintain normal oil and gas well production. Meanwhile, as oilfields enter the mid-to-late stages of development, the overall water cut increases, and the produced fluids, which are corrosive, prone to scaling, or have high wax content in the crude oil, easily lead to scaling and corrosion in the wellbore or corrosion of the production tubing and rod string, seriously affecting normal oilfield production. Chemical agents such as corrosion inhibitors, scale inhibitors, and wax removers are usually added to the well to address these problems. One common method of adding these chemical agents is through direct injection into the annulus, with the agent circulation flow being: annulus → screen → inside the tubing string → pumped out.

[0003] Currently, the sieve holes of common sieve tubes are all located on the radial sidewall of the outer tube. In specific applications, such as... Figure 9 As shown, the production tubing string, from top to bottom, includes the pump top tubing, the oil pump 300, the tubing 200, the screen pipe 500, and the tailpipe 400. When adding chemicals, the liquid corrosion inhibitors and other chemical agents are directly drawn into the tubing 200 through the radial screen holes on the side wall of the screen pipe 500. Within the range of "screen pipe 500 - tailpipe 400", the tubing string below the flow hole forms a "tubing string protection blind zone", which cannot effectively protect the tubing string in this section, and is prone to corrosion and wellbore fall due to corrosion of the tubing string or tailpipe below the screen pipe; or, a "casing protection blind zone" is formed in the casing section below the screen pipe, which also cannot effectively protect the casing section, and is prone to wellbore scaling or corrosion.

[0004] A double-layer sand-control screen pipe disclosed in Chinese Utility Model Patent No. CN204591236U, with an authorization announcement date of August 26, 2015, includes a perforated screen pipe and a slotted screen pipe coaxially disposed within the perforated screen pipe. The perforated screen pipe has circumferentially distributed flow holes on its side wall, and the slotted screen pipe has circumferentially distributed liquid inlet holes on its side wall. A sand-collecting pipe, connected to the perforated screen pipe via a coupling, is located at the bottom of the slotted screen pipe. In practical use, the added chemical agent is directly drawn into the oil pipe through the flow holes and liquid inlet holes. The screen pipe section below the flow holes and liquid inlet holes, as well as the sand-collecting pipe, cannot be effectively protected against corrosion, thus creating a blind spot in the protection. Utility Model Content

[0005] The purpose of this utility model is to provide a screen tube to solve the problem that existing screen tube structures have blind spots in corrosion protection and cannot effectively protect against corrosion.

[0006] To achieve the above objectives, the screen tube of this utility model adopts the following technical solution: a screen tube, including an outer tube and an inner tube sleeved inside the outer tube, the outer tube being connected to an oil pump through its upper tubing, the annulus between the inner tube and the outer tube and the lower port of the inner cavity of the inner tube being closed to form a sand settling cylinder, and the other port being provided with a grid to form a liquid inlet channel.

[0007] Furthermore, the annular space between the inner tube and the outer tube forms a liquid inlet channel, and the lower end of the inner cavity of the inner tube is closed to form a sand settling cylinder.

[0008] Furthermore, the inner cavity of the inner tube forms a liquid inlet channel, and the annular bottom end between the inner tube and the outer tube is closed to form a sand settling cylinder.

[0009] Furthermore, the grille is inclined from high to low in the direction from the outer tube to the inner tube, and the grille is provided with at least one stage.

[0010] Furthermore, the diameter of the flow holes in each stage of the grid decreases progressively along the liquid flow path, while the number of holes increases progressively.

[0011] Furthermore, the grids at each level are parallel to each other.

[0012] Furthermore, the inner tube has a sand settling hole above the connection between the inner tube and the grid, which connects the sand settling cylinder and the liquid inlet channel, and the inner tube does not have a sand settling hole above the connection between the bottom grid and the inner tube.

[0013] Furthermore, the screen tube includes a detachably connected liquid inlet section and an oil pipe section, the liquid inlet section and the oil pipe section respectively including an outer pipe and an inner pipe arranged in sections, and a grid connecting each section of the outer pipe and the inner pipe.

[0014] Furthermore, the screen tube also includes at least one stage screen tube section detachably connected between the liquid inlet section and the oil pipe section. The screen tube section includes a segmented outer tube and an inner tube, as well as a grid connecting the segmented outer tube and inner tube.

[0015] Furthermore, adjacent outer tubes that are segmented are connected by threads, and adjacent inner tubes that are segmented are connected by lap joints.

[0016] The beneficial effects of this utility model are as follows: The screen pipe provided by this utility model is an improvement on the existing technology. Through the combination of the inner and outer pipes, a liquid inlet channel is formed in the annulus between the inner and outer pipes. The lower end of the inner cavity of the inner pipe is closed to form a sand settling cylinder, or the inner cavity of the inner pipe forms the liquid inlet channel, and the bottom end of the annulus between the inner and outer pipes is closed to form a sand settling cylinder. A grid is installed at the liquid inlet port of the liquid inlet channel, so that the liquid inlet of the screen pipe is located at the axial bottom end of the screen pipe. When adding anti-corrosion and other chemical agents, the flow path of the agent is extended, ensuring that the part of the tubing string below the well fluid surface is entirely within the protective area of ​​the agent, eliminating the protective blind zone of the tubing string and preventing corrosion of the tubing string or tools from causing it to fall into the well; production... The liquid enters the inlet channel from the inlet at the bottom of the screen tube and flows upward along the outer tube into the inner cavity of the outer tube. During the flow of the produced liquid, it helps the sand particles or impurities in the produced liquid to settle under the action of gravity, improving the sand-liquid separation effect. At the same time, the sand settling structure is directly integrated into the screen tube, eliminating the need for separate tail pipes or other components to collect sand. This allows the screen tube to have the dual functions of a screen tube and a tail pipe, realizing the integration of "filtration-liquid inlet-sand settling" functions. The grid set at the inlet port of the inlet channel can achieve primary filtration protection, preventing large-diameter sand particles and other impurities from entering the inlet channel. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the screen tube structure of this utility model;

[0018] Figure 2 This is an exploded view of the structure of the sieve tube of this utility model;

[0019] Figure 3 This is an exploded view of another structure of the screen tube of this utility model;

[0020] Figure 4 This is a schematic diagram of the oil pipe short section structure of the screen tube of this utility model;

[0021] Figure 5 This is a schematic diagram of the short section structure of the screen tube of this utility model;

[0022] Figure 6 This is a schematic diagram of the liquid inlet section of the screen tube of this utility model;

[0023] Figure 7 This is a schematic diagram of the movement trajectory of the output liquid and impurities in the sieve tube of this utility model.

[0024] Figure 8 This is a schematic diagram of the application structure of the screen tube of this utility model;

[0025] Figure 9 This is a schematic diagram of the existing screen tube application structure and the flow direction of the reagents and output liquid.

[0026] In the figure: 100, screen tube (this utility model); 200, oil pipe; 300, oil pump; 400, tailpipe; 500, screen tube (existing technology); 101, inlet sub; 102, oil pipe sub; 103, screen tube sub;

[0027] 1. Outer pipe; 11. Lower pipe body; 12. Upper pipe body; 13. Short-connecting pipe body; 2. Inner pipe; 21. Lower inner pipe; 211. Sand settling hole; 22. Upper inner pipe; 23. Short-connecting inner pipe; 3. First grid; 31. Flow hole; 32. Second grid; 33. Third grid; 34. Fourth grid. Detailed Implementation

[0028] The features and performance of this utility model will be further described in detail below with reference to the embodiments.

[0029] This invention addresses the shortcomings of existing technologies where the pharmaceutical agent circulates through the annulus, screen tube, and production tubing, and the tail section below the screen tube cannot receive effective protection from the agent. It provides a screen tube with the inlet path located at the axial bottom end of the screen tube, thereby extending the flow path of the added agent. This ensures that the entire oil tubing is within the effective protection zone of the agent, and gives the screen tube both the functions of a screen tube and a tail tube.

[0030] An embodiment of the sieve tube in this utility model:

[0031] like Figure 1 and Figure 2 and refer to Figure 8 As shown, in this embodiment, the screen tube 100 includes an outer tube 1 and an inner tube 2 coaxially sleeved inside the outer tube 1. The outer tube 1 is connected to the oil pump 300 through an oil pipe 200. There is a gap between the inner tube 2 and the outer tube 1 to form an annulus. One of the annulus between the outer tube 1 and the inner tube 2 and the lower port of the inner cavity of the inner tube 2 are closed to form a sand settling cylinder, and the other port is provided with a grid to form a liquid inlet channel.

[0032] Specifically, the outer tube 1 is a hollow tubular structure with an internal thread at its upper end for connection with the oil pipe 200; one end of the inner tube 2 is an open end and the other end is a closed end, and the inner cavity of the inner tube 2 forms a sand settling cylinder; the annulus between the outer tube 1 and the inner tube 2 forms the liquid inlet channel of the screen tube, and a first grid 3 is provided at the liquid inlet port of the liquid inlet channel (i.e., the bottom end of the annulus); the first grid 3 is a circular annular plate structure with several flow holes 31 running through it along its thickness direction, and each flow hole 31 is evenly spaced along the circumference of the liquid inlet channel.

[0033] In another embodiment, both the outer tube and the inner tube are hollow tubular structures. The bottom of the annular space between the outer tube and the inner tube is closed so that the annular space forms a sand settling cylinder. The inner cavity of the inner tube forms the liquid inlet channel of the screen tube. A first grid is provided at the bottom end of the inner tube. The first grid is a circular mesh structure.

[0034] In the above embodiments, the combination of the inner tube 2 and the outer tube 1 forms a liquid inlet channel in the annular space between the inner tube 2 and the outer tube 1, or the inner cavity of the inner tube 2 forms a liquid inlet channel, and a grid is provided at the liquid inlet port of the liquid inlet channel, so that the liquid inlet of the screen tube 100 is located at the axial bottom end of the screen tube 100. In use, as... Figure 8 As shown, the screen pipe 100 is connected to the bottom of the production tubing. When adding corrosion inhibitors or other chemical agents, the agent enters the tubing from the inlet at the bottom axial end of the screen pipe 100, extending the flow path of the agent. This ensures that the portion of the tubing below the well fluid surface is entirely within the agent's protective zone, eliminating blind spots and preventing corrosion of the tubing or tools from causing it to fall into the well. The produced fluid enters the inlet channel from the inlet at the bottom axial end of the screen pipe 100, flows upwards along the outer pipe 1 to the top of the inlet channel, and then enters the inner cavity of the outer pipe 1. During the flow of the produced fluid, sand particles or... Impurities settle into the settling cylinder under gravity, improving the sand-liquid separation effect. At the same time, the lower end of the inner cavity of the inner tube 2 is closed to form the settling cylinder, or the bottom end of the annular space between the inner tube 2 and the outer tube 1 is closed to form the settling cylinder, so that the settling structure is directly integrated into the screen tube 100. There is no need to set up a separate tail pipe or other components to collect the settling sand. This makes the screen tube 100 provided by this utility model have the dual functions of screen tube and tail pipe, realizing the integration of "filtration-liquid inlet-sand settling" function. The grid set at the liquid inlet port of the liquid inlet channel can realize primary filtration protection to prevent large-diameter sand particles and other impurities from entering the liquid inlet channel.

[0035] As a further implementation method, such as Figure 6 As shown, the first grid 3 is inclined from high to low along the direction from the outer pipe 1 to the inner pipe 2, forming an angle between the grid and the radial direction of the outer pipe 1. The inclined grid can accommodate more flow holes 31, increasing the effective filtration area and ensuring a stable flow rate. The inclined grid forms a "slope" structure, so when sand-laden fluid flows through, sand particles and other impurities are less likely to adhere to the grid and block the inlet under the action of gravity. In addition, the inclined first grid 3 also forms a conical guide structure, which can play a guiding role during the insertion of the tubing string into the well. In other embodiments, the grid can be horizontally arranged.

[0036] As a further implementation method, such as Figure 6 As shown, the grating has two or more stages. Specifically, at least a second grating 32 parallel to the first grating 3 is also provided in the liquid inlet channel. The second grating 32 and the first grating 3 together constitute a two-stage filtration structure of the liquid inlet channel. Of course, more grating stages can be set in the liquid inlet channel as needed. The multi-stage grating forms a graded interception. After the produced liquid enters the liquid inlet channel, each stage of the grating can intercept impurities such as sand particles in the produced liquid. As the fluid flows in the liquid inlet channel, sand particles and other impurities are gradually separated, effectively improving the sand prevention efficiency.

[0037] To avoid a decrease in flow area due to an increase in the number of filter layers, such as Figure 1 And refer to Figure 7 As shown, in this embodiment, along the flow path of the downhole fluid, the aperture of the flow holes 31 of each stage of the grid gradually decreases, while the number of holes increases progressively. Multi-stage filtration is achieved through the decreasing aperture, forming a progressive sand control system that effectively improves sand control efficiency. The increase in the number of holes compensates for the decrease in the flow area per hole caused by the reduced aperture, maintaining a stable total flow area.

[0038] As a further implementation method, such as Figure 1 and Figure 6 As shown, a sand settling hole 211 is provided on the inner tube 2 above the connection between the inner tube 2 and the grid, connecting the sand settling cylinder and the liquid inlet channel. However, no sand settling hole 211 is provided on the inner tube 2 above the connection between the lowest grid and the inner tube 2. Specifically, a sand settling hole 211 is provided on the inner tube 2 above the connection between the second grid 32 and the inner tube 2, while no sand settling hole 211 is provided on the inner tube 2 above the connection between the first grid 3 and the inner tube 2. It should be understood that when multiple grids are provided, no sand settling hole 211 is provided on the inner tube 2 above the connection between the grid at the bottom end (or inlet port) of the liquid inlet channel and the inner tube 2. Figure 7 As shown, due to the inclined setting of the grid, the settling hole 211 is located in the inner tube and close to the lowest point of the grid. During the flow of the produced liquid in the inlet channel, impurities such as sand particles are gradually deposited to the lowest point of the previous grid under the obstruction of the next-stage grid and enter the settling cylinder through the settling hole 211 for storage. This reduces the retention of impurities such as sand particles in the inlet channel, improves the separation and filtration effect of the screen tube on impurities such as sand particles, reduces the risk of flow channel blockage caused by sand accumulation, and extends the service life of the screen tube. The lower part of the settling cylinder does not have a settling hole 211, which can prevent the liquid flow in the inlet channel from disturbing the bottom of the settling cylinder and destroying the settling effect.

[0039] As another implementation method, such as Figure 2 As shown, the screen pipe 100 has a segmented structure, including a tubing sub 102 for connection with the tubing 200 and a fluid inlet sub 101 detachably connected to the tubing sub 102. The segmented screen pipe structure facilitates manufacturing, processing, and assembly, and can be combined according to actual needs to meet the production requirements of oil wells with different sand production rates.

[0040] To illustrate the structure of the segmented screen tube in detail, this embodiment takes the annular space between the inner tube 2 and the outer tube 1 as an example, which forms the liquid inlet channel, and the lower end of the inner tube 2 is closed to form the sand settling cylinder.

[0041] like Figure 2 and Figure 6As shown, the liquid inlet section 101 includes a lower tube body 11 and a lower inner tube 21, as well as a first grid 3 and a second grid 32 connecting the lower tube body 11 and the lower inner tube 21.

[0042] like Figure 2 and Figure 4 As shown, the oil pipe section 102 includes an upper pipe body 12 and an upper inner pipe 22, as well as a third grid 33 connecting the upper pipe body 12 and the upper inner pipe 22. The third grid 33 is arranged parallel to the first grid 3.

[0043] After the tubing sub-section 102 and the fluid inlet sub-section 101 are connected by external pipe threads and internal pipe overlaps, a screen pipe 100 with a three-stage filtration structure and sand settling function is formed. The first grid 3, the second grid 32, and the third grid 33 constitute a multi-stage filtration structure for the fluid inlet channel. Along the flow path of the downhole fluid, the aperture of the flow holes 31 of the first grid 3, the second grid 32, and the third grid 33 decreases sequentially while the number of holes increases sequentially. The segmented external pipes, connected by threads, ensure the structural strength and sealing of the screen pipe, while the segmented internal pipes, connected by overlaps, allow for quick assembly and disassembly, improving assembly efficiency.

[0044] As a further implementation method, such as Figure 3 As shown, the screen tube 100 also includes at least one stage screen tube section 103 detachably connected between the liquid inlet section 101 and the oil pipe section 102, specifically, as... Figure 5 As shown, the screen pipe section 103 includes a short pipe body 13, a short inner pipe 23, and a fourth grid 34 connecting the short pipe body 13 and the short inner pipe 23. The fourth grid 34 is arranged parallel to the first grid 3. After the screen pipe section 103 is connected to the tubing section 102 and the fluid inlet section 101 by external pipe thread connection and internal pipe overlap, a screen pipe 100 with a four-stage filtration structure and sand settling function is formed. Along the flow path of the downhole fluid, the aperture of the flow holes 31 of the first grid 3, the second grid 32, the fourth grid 34, and the third grid 33 decreases sequentially, while the number of holes increases sequentially. It should be understood that in practical applications, different numbers of screen pipe sections 103 can be connected according to different well conditions to meet the production needs of oil wells with different sand production rates.

[0045] Finally, it should be noted that the above are merely preferred embodiments of this utility model and are not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some technical features, or organically combine different specific implementation methods to create the specific implementation methods shown in the accompanying drawings. Of course, those skilled in the art can also create other specific implementation methods not shown in the accompanying drawings. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A screen tube, comprising an outer tube and an inner tube sleeved within the outer tube, wherein the outer tube is connected to an oil pump via its upper tubing string, characterized in that: The annular space between the inner and outer tubes and the lower port of the inner cavity of the inner tube, one of which is closed, form a sand settling cylinder, and the other port is connected to a grid to form a liquid inlet channel.

2. The sieve tube according to claim 1, characterized in that: The annular space between the inner tube and the outer tube forms a liquid inlet channel, and the lower end of the inner cavity of the inner tube is closed to form a sand settling cylinder.

3. The sieve tube according to claim 1, characterized in that: The inner cavity of the inner tube forms a liquid inlet channel, and the annular bottom end between the inner tube and the outer tube is closed to form a sand settling cylinder.

4. The sieve tube according to claim 1 or 2, characterized in that: The grille is inclined from high to low in the direction from the outer tube to the inner tube, and the grille is provided with at least one stage.

5. The sieve tube according to claim 4, characterized in that: The diameter of the flow holes in each level of the grid decreases progressively along the liquid flow path, while the number of holes increases progressively.

6. The sieve tube according to claim 4, characterized in that: The grilles at each level are parallel to each other.

7. The sieve tube according to claim 1 or 2, characterized in that: The inner tube has a sand settling hole above the connection between the inner tube and the grid, which connects the sand settling cylinder and the liquid inlet channel. However, the inner tube does not have a sand settling hole above the connection between the bottom grid and the inner tube.

8. The sieve tube according to claim 1, 2, or 3, characterized in that: The screen tube includes a detachably connected liquid inlet section and an oil pipe section. The liquid inlet section and the oil pipe section each include a segmented outer pipe and an inner pipe, as well as a grid connecting the segmented outer pipe and inner pipe.

9. The sieve tube according to claim 8, characterized in that: The screen tube also includes at least one stage screen tube section detachably connected between the liquid inlet section and the oil pipe section. The screen tube section includes a segmented outer tube and an inner tube, as well as a grid connecting the segmented outer tube and inner tube.

10. The sieve tube according to claim 8, characterized in that: Adjacent outer pipes in segmented configurations are connected by threads, while adjacent inner pipes in segmented configurations are connected by lap joints.

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