A kind of side tracking slim hole sand control completion pipe column and special tool and method

Abstract

The application discloses a side-tracking slim hole sand prevention and completion pipe column and special tools and methods, which comprises an outer pipe column and an inner pipe column, wherein the inner pipe column is arranged inside the outer pipe column; the outer pipe column comprises, from top to bottom, a multi-stage high-efficiency sealing and filling tool and a screen pipe which are sequentially connected to a tubing; and the inner pipe column comprises, from top to bottom, a sandwich channel, a ball seat and a sandwich inner pipe which are sequentially connected. The application further improves the construction displacement, increases the filling saturation and improves the sand blocking barrier strength. After filling, the integrated consolidation is left in the well, multiple sand blocking barriers are formed, the sand prevention effect is effectively improved, and the difficulty of post-processing is reduced. The application solves the problem that the sealing tool of the multi-stage high-efficiency sealing and filling tool is opened in advance due to high pressure caused by special conditions during the pipe column lowering process, and the pipe column is difficult to be lowered.

Description

Technical Field

[0001] This invention relates to the field of sand control completion technology, specifically to a sand control completion string, special tools, and method for side-drilling small-bore wells. Background Technology

[0002] Currently, for small-diameter casing wells, due to the limited size of the wellbore and the constraints on the size of the extrusion packing tools, methods such as tubing-based packing, suspended small-diameter filter pipes, or chemical sand control are commonly used. Simply using tubing-based packing suffers from limited drainage capacity, insufficient formation packing saturation, and the inability to perform circulating packing, resulting in a single sand barrier and unsatisfactory sand control effect. While suspended small-diameter filter pipes offer sand control, the small wellbore makes post-processing difficult. Furthermore, chemical sand control has a short effective period, failing to meet the demands of high-efficiency sand control in the field. To address these issues, a sidetracked small-diameter well sand control completion string and method are proposed.

[0003] Announcement No.: CN205558879U, Announcement Date: 2016-09-07 This is a sand-control and filling tool for oil and water wells. It is reliable in operation and can meet the development requirements of highly deviated offshore wells. It includes a setting mechanism, a release mechanism, and a circulation mechanism. The upper part of the inner central tube is connected to the release mechanism, and the lower part is connected sequentially to the lower valve body and the flushing pipe joint of the circulation mechanism. A seal is provided between the flushing pipe joint and the lower joint. The setting ball of the setting mechanism is seated on the top of the lower valve body. A spring and a spring pressure plate are installed above the setting ball. The spring pressure plate is fixed in the inner central tube and has a flow hole on its plate. The release slider and bearing of the release mechanism have an axial flow groove, which, together with the flow hole of the spring pressure plate and the circulation filling gap between the inner and outer central tubes, forms a circulation filling channel. Compared to this patent, the aforementioned existing technologies mainly suffer from difficulties in meeting the sand control requirements of small-diameter wellbore filling. Their structural design results in limited annular space in small wellbores. Furthermore, their spring and spring-plate structure poses a risk of sand entering the spring gaps during filling, leading to malfunction. This patent, through a small casing filling method, eliminates the need for tubing, significantly simplifying the tubing string structure, increasing the annular space, enabling compression-circulation filling, and employing a leaf spring sealing structure to solve the sand jamming problem, resulting in high safety and reliability.

[0004] Publication No.: CN102102503A, Publication Date: 2011-06-22 This invention relates to a sand control method for 4-inch small-diameter wells, implemented according to the following steps: (1) Run a 4-inch small-diameter well gauge to the designed depth; (2) Run a 4-inch small-diameter scraper to scrape the well, and then backwash the well with hot water for 2-4 weeks; (3) Run a resin-filled sand tubing string; (4) Install a high-pressure wellhead, connect the pipeline, and carry out resin-filled sand construction; (5) Deepen the tubing to flush sand to the artificial well bottom; (6) Run a 4-inch small-diameter mechanical sand control tubing string; (7) Pressurize the surface to achieve setting and release, and the mechanical sand control tubing string forms a completion tubing string in the well. Compared with this patent, the above-mentioned prior art adopts the method of running tubing first to squeeze and fill the formation, and then hanging the mechanical sand control tubing string. It cannot achieve cyclic filling, and there is a problem of sand backflow caused by flushing sand after formation squeezing and filling, making it difficult to guarantee the filling effect. Furthermore, the mechanical sand control tubing used presents certain challenges in post-processing. This patented innovative small-casing extrusion filling method for side-drilling further increases the drilling displacement, filling saturation, and sand barrier strength compared to secondary small tubing ground filling. It also enables circulating filling within small wellbores and employs a drillable screen and coated sand design, resulting in integrated solidification within the well after filling, forming multiple sand barriers that effectively improve sand control. Simultaneously, the drillable sand barrier reduces the difficulty of post-processing.

[0005] Announcement No.: CN104533354B, Announcement Date: 2017-02-22 This invention relates to a small-bore side-drilling plug-type sand control method, comprising the following steps: S1. Retrieve the production tubing; S2. Lower the sand flushing tubing; S3. Perform sand flushing operation after the sand flushing tubing reaches the sand surface; S4. Complete the sand control tubing; S5. Pressure test the surface pipeline; S6. Fill the wellbore; S7. Pre-fill with fluid; S8. Fill the wellbore with plug-type gravel; S9. Displacement fluid; S10. Wait for it to set; S11. Drill plug and leave the plug. Compared to this patent, the prior art uses a post-filling drilling plug method, which reduces the risk during filling. However, in small wellbores, the later drilling plug can cause destructive effects such as vibration and breakage of the formed sand-blocking plug, making it difficult to guarantee the stability of the sand barrier. This patented technology uses a small casing extrusion filling method, which can achieve circulating filling in small wellbores. It also adopts a drillable screen pipe and coated sand design, which is integrated and solidified in the well after filling, forming multiple sand-blocking barriers and effectively improving the sand control effect. Summary of the Invention

[0006] The purpose of this invention is to provide a sand control completion string, specialized tools, and method for side-drilling small-bore wells, which further improves the drilling displacement, increases the filling saturation, and enhances the strength of the sand barrier. After filling, the material is integrally solidified within the well, forming multiple sand barriers, effectively improving sand control performance while reducing the difficulty of post-processing. This invention also solves the problem of premature opening of the filling port due to high pressure under special circumstances during string running, causing the sealing tools of the multi-stage high-efficiency sealing filling tool to expand prematurely, making string running difficult.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A side-drilling small-bore sand control completion string includes an outer string and an inner string, wherein the inner string is placed inside the outer string;

[0009] The outer tubing string includes a multi-stage high-efficiency sealing and filling tool and a screen pipe connected sequentially from top to bottom to the tubing; the inner tubing string includes a clamping wall channel, a ball seat, and a clamping wall inner tube connected sequentially from top to bottom.

[0010] The outer tubing also includes a multi-functional safety connector, which connects the multi-stage high-efficiency sealing and filling tool and the screen tube;

[0011] The bottom end of the inner tube of the clamp wall is also provided with a bottom liquid outlet;

[0012] The outer wall of the inner tube of the clamp wall is connected and fixed to the inner wall of the multi-stage high-efficiency sealing and filling tool through an annular blind plate.

[0013] The multi-stage high-efficiency sealing and filling tool includes a self-sealing sliding sleeve and a sealing tool, which are sequentially fitted onto the outer wall of the base pipe from top to bottom. The base pipe has a filling port with a corresponding sliding switch of the self-sealing sliding sleeve, and the annular blind plate is positioned below the filling port.

[0014] The self-sealing sleeve includes a retaining ring, an anti-jamming sealing pressure tool, and a sliding switch connected in sequence from top to bottom.

[0015] The multi-stage high-efficiency sealing and filling tool also includes an upper connector, a pressure ring, and a connecting sleeve connected in sequence from top to bottom, wherein the lower end of the connecting sleeve is connected to the retaining ring at the upper end of the self-sealing sliding sleeve.

[0016] The anti-jamming sealing pressure tool includes at least one set of spring plate structures. Each set of spring plate structures includes two oppositely placed annular spring plates with arc-shaped cross sections. The spring plates are pressed between the upper retaining ring and the lower sliding switch by a preload.

[0017] Each leaf spring is equipped with a sealing strip at the top and middle position; the bottom leaf spring of this anti-jamming sealing pressure tool is welded to the top of the sliding switch.

[0018] The sealing tool includes, from top to bottom, a sliding sleeve positioning tool, a retaining sleeve, a leather cup, and a clamping ring;

[0019] The clamping ring is provided with a through hole, and the outer edge of the clamping ring is provided with a beveled hook to hook and press the edge of the cup; the sliding sleeve positioning tool is fixed to the base tube; the sliding sleeve positioning tool is used to position the sliding switch and press the cup.

[0020] The inner wall of the sliding switch is provided with an upper sealing ring for sealing the filling port. The outer wall of the sliding switch and the inner wall of the sliding sleeve positioning tool are in close contact, and a wedge-shaped sealing ring is installed between them. The lower end face of the sliding switch and the lower end face of the filling port have a liquid outlet gap, so that the sliding switch is equivalent to a piston and the sliding sleeve positioning tool is equivalent to a piston sleeve.

[0021] A lower sealing ring is provided between the contact surface of the retaining sleeve and the base tube.

[0022] The clamping channel is assembled with the base tube of the multi-stage high-efficiency sealing and filling tool, and there are two non-communicating fluid flow channels between them; wherein, the second channel connects the inside of the base tube and the annulus between the base tube and the oil tube, and the first channel connects the annulus between the oil tube and the casing.

[0023] To achieve the above objectives, the present invention adopts the following technical solution:

[0024] A method for using a sand-control completion string in a side-drilled small-bore well includes the following steps:

[0025] Step 1: Throw the ball. The ball is sealed on the ball seat. Pressurize the oil pipe. The hydraulic fluid flows from channel 2 of the clamp wall channel to the filling port. The pressure will lift the sliding switch and disengage it from the sealing sleeve positioning tool, thus opening the filling port.

[0026] Step 2: Pump filling mortar into the oil pipe. The mortar enters the annulus between the inner pipe and the oil pipe through channel 2 from inside the oil pipe. It then enters the annulus between the oil pipe and the casing through the filling port. After the diaphragm is compressed, a gap is formed between it and the casing. The mortar passes through this gap to circulate and fill the screen pipe section. The coating sand in the mortar is deposited in the screen pipe section and solidifies with the screen pipe under certain conditions.

[0027] When enough coating sand has accumulated outside the screen tube section, the pressure will increase. Subsequently, the liquid enters the through hole of the clamping ring, and the septum of the sealing tool expands under pressure. The septum tightly adheres to the outer sleeve to form a seal, which can prevent the liquid / mortar from flowing back.

[0028] The liquid in the mortar enters the interior of the inner tube of the clamp wall through the gap of the screen tube and the bottom liquid outlet. After passing through the ball seat hole, it returns through the channel and the annulus between the oil pipe and the casing. The ball that was thrown is also flushed out.

[0029] Step 3: Stop the pump; the sliding switch moves downward under the action of the anti-jamming sealing pressure tool to close the filling port; at the same time, the diaphragm automatically expands to seal the annulus between the oil pipe and the casing to prevent the backflow of filling sand or formation sand.

[0030] Includes the following steps:

[0031] Step 4: Remove the upper tubing from the multi-functional safety joint by rotating the tubing forward or by pulling it off, leaving the lower tubing in the well.

[0032] To achieve the above objectives, the present invention adopts the following technical solution:

[0033] A multi-stage high-efficiency sealing and filling tool for sand control completion string in side-drilling small wells includes a self-sealing sliding sleeve and a sealing tool that are sequentially fitted on the outer wall of the base pipe from top to bottom. The base pipe has a filling port with a sliding switch corresponding to the self-sealing sliding sleeve.

[0034] The self-sealing sleeve includes a retaining ring, an anti-jamming sealing pressure tool, and a sliding switch connected sequentially from top to bottom;

[0035] The anti-jamming sealing pressure tool includes at least one set of spring plate structures. Each set of spring plate structures includes two oppositely placed annular spring plates with arc-shaped cross sections. The spring plates are pressed between the upper retaining ring and the lower sliding switch by a preload.

[0036] The multi-stage high-efficiency sealing and filling tool also includes an upper connector, a pressure ring, and a connecting sleeve connected in sequence from top to bottom, wherein the lower end of the connecting sleeve is connected to the retaining ring at the upper end of the self-sealing sliding sleeve.

[0037] Each leaf spring is equipped with a sealing strip at the top and middle position; the bottom leaf spring of this anti-jamming sealing pressure tool is welded to the top of the sliding switch.

[0038] The sealing tool includes, from top to bottom, a sliding sleeve positioning tool, a retaining sleeve, a leather cup, and a clamping ring;

[0039] The clamping ring is provided with a through hole, and the outer edge of the clamping ring is provided with a beveled hook to hook and press the edge of the cup; the sliding sleeve positioning tool is fixed to the base tube; the sliding sleeve positioning tool is used to position the sliding switch and press the cup.

[0040] The inner wall of the sliding switch is provided with an upper sealing ring for sealing the filling port. The outer wall of the sliding switch and the inner wall of the sliding sleeve positioning tool are in close contact, and a wedge-shaped sealing ring is installed between them. A liquid outlet gap is left between the lower end face of the sliding switch and the lower end face of the filling port, so that the sliding switch is equivalent to a piston and the sliding sleeve positioning tool is equivalent to a piston sleeve. A lower sealing ring is provided between the contact surface of the retaining sleeve and the base tube.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] (1) This method adopts an innovative side-drilling small casing extrusion filling method, which further improves the construction displacement, increases the filling saturation, and improves the sand barrier strength compared with the secondary small tubing ground filling.

[0043] (2) The tubing string is designed to achieve circulating filling in small wellbores through an overall structural design. It adopts a drillable screen pipe and coated sand design, and after filling, it is integrated and solidified in the well, forming multiple sand-blocking barriers, which effectively improves the sand control effect. At the same time, the drillable sand-blocking barrier in the well reduces the difficulty of post-processing.

[0044] (3) The tubing has innovated a multi-stage high-efficiency sealing and filling tool. Through the design of the anti-jamming sealing pressure tool, the construction is more safe and reliable. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of a side-drilling small-bore sand-control completion string according to the present invention;

[0046] Figure 2 A schematic diagram of a multi-stage high-efficiency sealing and filling tool;

[0047] Figure 3 A half-section view of a pressure tool designed to prevent jamming and sealing.

[0048] Figure 4 This is a schematic diagram of the cyclic filling process.

[0049] In the diagram: 1. Casing; 2. Perforation hole; 3. Oil pipe; 4. Multi-stage high-efficiency sealing and filling tool; 5. Multi-functional safety joint; 6. Screen pipe; 7. Clamped wall channel; 8. Ball seat; 9. Clamped wall inner tube; 10. Bottom liquid outlet.

[0050] Upper connector 401, pressure ring 402, connecting sleeve 403, self-sealing sliding sleeve 404, sealing tool 405, base tube 406. Retaining ring 404-1, anti-jamming sealing pressure tool 404-2, sliding switch 404-3, upper sealing ring 404-4, wedge-shaped sealing ring 404-5. Lower sealing ring 405-1, retaining sleeve 405-3, leather cup 405-4, clamping ring 405-5, through hole 405-6. Filling port 406-1.

[0051] 404-2-1 leaf spring, 404-2-2 sealing strip. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1:

[0054] like Figures 1 to 4 As shown, the present invention provides a side-drilling small-bore sand-control completion string, comprising:

[0055] This invention mainly comprises an outer tubing string and an inner tubing string. The outer tubing string consists of an oil pipe 3, a multi-stage high-efficiency sealing and filling tool 4, a multi-functional safety joint 5, and a screen pipe 6 connected sequentially from top to bottom. The inner tubing string consists of a clamped wall channel 7, a ball seat 8, a clamped wall inner tube 9, and a bottom fluid outlet 10 connected sequentially from top to bottom.

[0056] The oil pipe 3 is threadedly connected to the multi-stage high-efficiency sealing and filling tool 4.

[0057] The upper part of the multi-functional safety connector 5 is threadedly connected to the multi-stage high-efficiency sealing and filling tool 4, and the lower part is threadedly connected to the screen tube 6. It is made of drillable material for easy post-processing.

[0058] The multi-stage high-efficiency sealing and filling tool 4 includes an upper connector 401, a pressure ring 402, a connecting sleeve 403, a self-sealing sliding sleeve 404, a sealing tool 405, and a base pipe 406. The upper connector 401 is threaded to the upper oil pipe at the top and connected to the base pipe 406 at the bottom through the pressure ring 402 and the connecting sleeve 403.

[0059] The self-sealing sleeve 404 includes a retaining ring 404-1, an anti-jamming sealing pressure tool 404-2, a sliding switch 404-3, an upper sealing ring 404-4, and a wedge-shaped sealing ring 404-5.

[0060] The sealing tool 405 includes a lower sealing ring 405-1, a sliding sleeve positioning tool 405-2, a retaining sleeve 405-3, a leather cup 405-4, and a clamping ring 405-5. The clamping ring 405-5 has a through hole 405-6. The lower sealing ring 405-1 seals the contact surface between the retaining sleeve 405-3 and the base tube 406. The sliding sleeve positioning tool 405-2 is threaded and can be fixed to the base tube 6 by the threads. The sliding sleeve positioning tool 405-2 is used to position the sliding switch 404-3 and can clamp the sealing tool 405. The sliding sleeve positioning tool 405-2, with its threads, can be fixed to the base tube 406. It is used to position the sliding switch 404-3 and clamp the sealing tool 405. A sealing ring between it, the retaining sleeve 405-3, and the base tube 406 prevents water leakage.

[0061] The anti-jamming sealing pressure tool 404-2 includes multiple sets of spring plate structures. Each set of spring plate structures includes two oppositely placed arc-shaped annular spring plates 404-2-1. The spring plates 404-2-1 are pressed and fixed between the upper retaining ring 404-1 and the lower sliding switch 404-3 by preload. Sealing strips 404-2-2 are provided at the upper and middle positions of each spring plate 404-2-1 to achieve a good seal. The lowermost spring plate 404-2-1 of the anti-jamming sealing pressure tool 404-2 is welded to the upper part of the sliding switch 404-3. This design is safer than conventional spring designs. On the one hand, the sealing strip design can prevent filling sand from getting stuck in the spring and affecting its normal operation. On the other hand, the anti-jamming sealing pressure tool 404-2 solves the problem that the filling port 406-1 may open prematurely due to high pressure caused by special circumstances during the tubing insertion process, causing the sealing tool 405 of the multi-stage high-efficiency sealing filling tool 4 to expand prematurely, making it difficult to insert the tubing.

[0062] An upper sealing ring 404-4 is provided between the sliding switch 404-3 and the base tube 406, and a wedge-shaped sealing ring 404-5 is provided between the sliding switch 404-3 and the sealing tool 405. When the tubing is lowered into place, the oil pipe is pressurized after the ball is thrown. When the pressure reaches a certain value, the anti-jamming sealing pressure tool 404-2 contracts, driving the sliding switch 404-3 upward, and leaking out the filling port 406-1. Liquid enters the cavity of the sealing tool 405 through the annular space between the oil pipe 3 and the sleeve 1 through the through hole 405-6. When the pressure reaches a certain value, the cup 405-4 of the sealing tool 405 expands under pressure, popping open the clamping ring 405-5. The cup 405-4 tightly adheres to the outer sleeve to form a seal, which can prevent liquid / mortar backflow, but under hydraulic action, liquid is allowed to flow from top to bottom. The clamping ring 405-5 wraps around the cup 405-4 during the tubing insertion process, reducing resistance during insertion and effectively protecting the cup 405-4. The wedge-shaped sealing ring 404-5 is designed to fit the sealing slope and ensure excellent sealing performance.

[0063] The clamping channel 7 is fitted together with the base tube 406 of the multi-stage high-efficiency sealing and filling tool 4, and the two are connected by two non-communicating fluid flow channels, namely, channel one 701 and channel two 702. Channel two 702 connects the interior of the base tube 406 and the annulus between the base tube 406 and the tubing. Channel one 701 connects the annulus between the tubing and the casing.

[0064] Liquid flow channels 701 and 702 are not connected, and the sandwiched channel 7 is a sandwiched structure. For ease of understanding, in... Figure 1The diagram includes dividing lines. Channel 701 is drawn as a solid line, and channel 702 as a dashed line. They form a spatial structure similar to an overpass, appearing to intersect in plan view but not actually connected. Channels 701 and 702 each connect to the interior of channel 406 via their own channels. This type of structure is well-known to technicians in the mechanical field and is a standard drawing method in mechanical drafting.

[0065] The ball seat is welded to the inner tube 9 of the clamp wall and is used for cyclic filling by throwing a ball, followed by pressurization and filling. After the ball is thrown, it blocks the ball seat, forming a one-way ball valve.

[0066] The bottom liquid outlet 10 is threaded to the bottom of the inner tube 9 of the clamp wall.

[0067] Example 2:

[0068] The multi-stage high-efficiency sealing and filling tool 4 includes an upper connector 401, a pressure ring 402, a connecting sleeve 403, a self-sealing sliding sleeve 404, a sealing tool 405, and a base pipe 406. The upper connector 401 is threaded to the upper oil pipe at the top and connected to the base pipe 406 at the bottom through the pressure ring 402 and the connecting sleeve 403.

[0069] The self-sealing sleeve 404 includes a retaining ring 404-1, an anti-jamming sealing pressure tool 404-2, a sliding switch 404-3, an upper sealing ring 404-4, and a wedge-shaped sealing ring 404-5.

[0070] The sealing tool 405 includes a lower sealing ring 405-1, a sliding sleeve positioning tool 405-2, a retaining sleeve 405-3, a leather cup 405-4, and a clamping ring 405-5. The clamping ring 405-5 has a through hole 405-6. The lower sealing ring 405-1 seals the contact surface between the retaining sleeve 405-3 and the base tube 406. The sliding sleeve positioning tool 405-2 is threaded and can be fixed to the base tube 6 by the threads. The sliding sleeve positioning tool 405-2 is used to position the sliding switch 404-3 and can clamp the sealing tool 405. The sliding sleeve positioning tool 405-2, with its threads, can be fixed to the base tube 406. It is used to position the sliding switch 404-3 and clamp the sealing tool 405. A sealing ring between it, the retaining sleeve 405-3, and the base tube 406 prevents water leakage.

[0071] The anti-jamming sealing pressure tool 404-2 includes multiple sets of spring plate structures. Each set of spring plate structures includes two oppositely placed arc-shaped annular spring plates 404-2-1. The spring plates 404-2-1 are pressed and fixed between the upper retaining ring 404-1 and the lower sliding switch 404-3 by preload. Sealing strips 404-2-2 are provided at the upper and middle positions of each spring plate 404-2-1 to achieve a good seal. The lowermost spring plate 404-2-1 of the anti-jamming sealing pressure tool 404-2 is welded to the upper part of the sliding switch 404-3. This design is safer than conventional spring designs. On the one hand, the sealing strip design can prevent filling sand from getting stuck in the spring and affecting its normal operation. On the other hand, the anti-jamming sealing pressure tool 404-2 solves the problem that the filling port 406-1 may open prematurely due to high pressure caused by special circumstances during the tubing insertion process, causing the sealing tool 405 of the multi-stage high-efficiency sealing filling tool 4 to expand prematurely, making it difficult to insert the tubing.

[0072] Example 3:

[0073] A method for sand control and completion in small-bore side-drilling wells includes the following steps:

[0074] Step 1: Perform pressure testing on the original small casing well casing. After the pressure test is passed, use the original casing for extrusion filling construction through the wellhead.

[0075] Step 2: After assembling the tubing according to the design, lower it into the predetermined position in the well.

[0076] Step 3: Throw the ball and pressurize the oil pipe. When the pressure reaches a certain level, open the filling port 406-1.

[0077] Step 4: Pump filling mortar (using coated sand as filling material) into the oil pipe. The mortar enters the annulus between the inner tube 9 and the oil pipe through channel 2 702 from inside the oil pipe, and then enters the annulus between the oil pipe 3 and the casing 1 through filling port 406-1. After the cup is compressed, a gap is formed between it and the casing 1. The mortar passes through this gap to circulate and fill the screen tube 6 section. The coated sand in the mortar is deposited in the screen tube 6 section and solidifies with the screen tube 6 under certain conditions. The liquid in the mortar enters the interior of the inner tube 9 through the gap in the screen tube 6 and the bottom liquid outlet 10. After passing through the orifice of the ball seat 8, it returns through channel 1 701 through the annulus between the oil pipe 3 and the casing 1, and the thrown ball is also flushed out. When enough coating sand is deposited outside section 6 of the screen tube, the pressure will increase. When the pressure reaches a certain value, the septum cup 405-4 of the sealing tool 405 will expand under pressure, and the liquid will enter the through hole 405-6, which will pop open the clamping ring 405-5. The septum cup 405-4 will then be tightly pressed against the outer sleeve to form a seal, which can prevent the liquid / mortar from flowing back.

[0078] Step 5: Stop the pump. The sliding switch 404-3, under the action of the anti-jamming sealing pressure tool 404-2, moves downwards to close the filling port 406-1. Simultaneously, the piston cup automatically expands to seal the annulus between the oil pipe 3 and the casing 1, preventing the backflow of filling sand or formation sand.

[0079] Step 6: Remove the upper tubing from point 5 of the multi-functional safety joint by rotating the tubing forward or by pulling it off, leaving the lower tubing in the well.

[0080] This invention employs an innovative side-drilling small casing extrusion filling method, which further increases the construction displacement, filling saturation, and sand barrier strength compared to secondary small tubing ground filling. Secondly, the tubing string, through its integrated structural design, enables circulating filling within small wellbores. Furthermore, the use of a drillable screen and coated sand design ensures that the filled material is integrally solidified within the well, forming multiple sand barriers that effectively improve sand control while reducing post-processing difficulty. In addition, the tubing string features an innovative multi-stage high-efficiency sealing filling tool. The anti-jamming sealing pressure tool design prevents filling sand from getting stuck in the spring and affecting its normal operation. Moreover, the number and curvature of the leaf springs in the anti-jamming sealing pressure tool can be designed differently according to the pressure level, solving the problem of premature opening of the filling port due to high pressure during tubing string running, which would cause the sealing tool of the multi-stage high-efficiency sealing filling tool to expand prematurely and make tubing string difficult to run.

[0081] All components not discussed in detail in this application, as well as the connection methods of these components, are well-known technologies in this field. They can be directly applied and will not be elaborated further.

[0082] In this invention, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0083] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0084] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A side-drilling small-bore sand control completion string, comprising an outer string and an inner string, wherein the inner string is placed inside the outer string; Its features are, The outer tubing string includes a multi-stage high-efficiency sealing and filling tool and a screen pipe connected sequentially from top to bottom to the tubing; the inner tubing string includes a clamping wall channel, a ball seat, and a clamping wall inner tube connected sequentially from top to bottom. The outer wall of the inner tube of the clamp wall is connected and fixed to the inner wall of the multi-stage high-efficiency sealing and filling tool through an annular blind plate; The multi-stage high-efficiency sealing and filling tool includes a self-sealing sliding sleeve and a sealing tool, which are sequentially fitted onto the outer wall of the base pipe from top to bottom. The base pipe has a filling port with a corresponding sliding switch of the self-sealing sliding sleeve, and the annular blind plate is positioned below the filling port. The self-sealing sleeve includes a retaining ring, an anti-jamming sealing pressure tool, and a sliding switch connected sequentially from top to bottom; The anti-jamming sealing pressure tool includes at least one set of spring plate structures. Each set of spring plate structures includes two oppositely placed annular spring plates with arc-shaped cross sections. The spring plates are pressed between the upper retaining ring and the lower sliding switch by a preload. The inner wall of the sliding switch is provided with an upper sealing ring for sealing the filling port. The outer wall of the sliding switch and the inner wall of the sliding sleeve positioning tool are in close contact, and a wedge-shaped sealing ring is installed between them. The lower end face of the sliding switch and the lower end face of the filling port have a liquid outlet gap, so that the sliding switch is equivalent to a piston and the sliding sleeve positioning tool is equivalent to a piston sleeve.

2. The side-drilling small-bore sand-control completion string according to claim 1, characterized in that, The outer tubular column also includes a multi-functional safety connector that connects the multi-stage high-efficiency sealing and filling tool and the screen tube; The bottom of the inner tube of the clamp wall is also provided with a bottom liquid outlet.

3. The side-drilling small-bore sand-control completion string according to claim 2, characterized in that, The multi-stage high-efficiency sealing and filling tool also includes an upper connector, a pressure ring, and a connecting sleeve connected in sequence from top to bottom, wherein the lower end of the connecting sleeve is connected to the retaining ring at the upper end of the self-sealing sliding sleeve.

4. The side-drilling small-bore sand-control completion string according to claim 3, characterized in that, Each leaf spring is equipped with a sealing strip at the top and middle position; the bottom leaf spring of this anti-jamming sealing pressure tool is welded to the top of the sliding switch.

5. A side-drilling small-bore sand-control completion string according to claim 3, characterized in that, The sealing tool includes, from top to bottom, a sliding sleeve positioning tool, a retaining sleeve, a leather cup, and a clamping ring; The clamping ring is provided with a through hole, and the outer edge of the clamping ring is provided with a beveled hook edge to hook and press the edge of the cup of the leather cup; the sliding sleeve positioning tool is fixed to the base tube; the sliding sleeve positioning tool is used to position the sliding switch and press the leather cup. A lower sealing ring is provided between the contact surface of the retaining sleeve and the base tube.

6. The side-drilling small-bore sand-control completion string according to claim 5, characterized in that, The clamping channel is assembled with the base tube of the multi-stage high-efficiency sealing and filling tool, and there are two non-communicating fluid flow channels between them; wherein, the second channel connects the inside of the base tube and the annulus between the base tube and the oil tube, and the first channel connects the annulus between the oil tube and the casing.

7. A method for using a sand-control completion string in a small-bore side-drilling well, characterized in that, Using the side-drilling small-bore sand-control completion string as described in claim 6 includes the following steps: Step 1: Throw the ball. The ball is sealed on the ball seat. Pressurize the oil pipe. The hydraulic fluid flows from channel 2 of the clamp wall channel to the filling port. The pressure will lift the sliding switch and disengage it from the sealing sleeve positioning tool, thus opening the filling port. Step 2: Pump filling mortar into the oil pipe. The mortar enters the annulus between the inner pipe and the oil pipe through channel 2 from inside the oil pipe. It then enters the annulus between the oil pipe and the casing through the filling port. After the diaphragm is compressed, a gap is formed between it and the casing. The mortar passes through this gap to circulate and fill the screen pipe section. The coating sand in the mortar is deposited in the screen pipe section and solidifies with the screen pipe under certain conditions. When enough coating sand has accumulated outside the screen tube section, the pressure will increase. Subsequently, the liquid enters the through hole of the clamping ring, and the septum of the sealing tool expands under pressure. The septum tightly adheres to the outer sleeve to form a seal, which can prevent the liquid / mortar from flowing back. The liquid in the mortar enters the interior of the inner tube of the clamp wall through the gap of the screen tube and the bottom liquid outlet. After passing through the ball seat hole, it returns through the channel and the annulus between the oil pipe and the casing. The ball thrown is also flushed out. Step 3: Stop the pump; the sliding switch moves downward under the action of the anti-jamming sealing pressure tool to close the filling port; at the same time, the diaphragm automatically expands to seal the annulus between the oil pipe and the casing to prevent the backflow of filling sand or formation sand.

8. The method of using a side-drilling small-bore sand-control completion string according to claim 7, characterized in that, Includes the following steps: Step 4: Remove the upper tubing from the multi-functional safety joint by rotating the tubing forward or by pulling it off, leaving the lower tubing in the well.

9. A multi-stage high-efficiency sealing and filling tool for sand control completion string in small side-drilling wells, comprising a self-sealing sliding sleeve and a sealing tool sequentially mounted on the outer wall of the base pipe from top to bottom, wherein the base pipe has a filling port with a sliding switch corresponding to the self-sealing sliding sleeve; Its features are, The self-sealing sleeve includes a retaining ring, an anti-jamming sealing pressure tool, and a sliding switch connected sequentially from top to bottom; The anti-jamming sealing pressure tool includes at least one set of spring plate structures. Each set of spring plate structures includes two oppositely placed annular spring plates with arc-shaped cross sections. The spring plates are pressed between the upper retaining ring and the lower sliding switch by a preload. Each leaf spring is equipped with a sealing strip at the top and middle; the bottom leaf spring of this anti-jamming sealing pressure tool is welded to the top of the sliding switch. The sealing tool includes, from top to bottom, a sliding sleeve positioning tool, a retaining sleeve, a leather cup, and a clamping ring; The clamping ring is provided with a through hole, and the outer edge of the clamping ring is provided with a beveled hook to hook and press the edge of the cup; the sliding sleeve positioning tool is fixed to the base tube; the sliding sleeve positioning tool is used to position the sliding switch and press the cup.

10. A multi-stage high-efficiency sealing and filling tool for side-drilling small-bore sand control completion tubing as described in claim 9, characterized in that, The multi-stage high-efficiency sealing and filling tool also includes an upper connector, a pressure ring, and a connecting sleeve connected in sequence from top to bottom, wherein the lower end of the connecting sleeve is connected to the retaining ring at the upper end of the self-sealing sliding sleeve.

11. A multi-stage high-efficiency sealing and filling tool for side-drilling small-bore sand control completion tubing as described in claim 9, characterized in that, The inner wall of the sliding switch is provided with an upper sealing ring for sealing the filling port. The outer wall of the sliding switch and the inner wall of the sliding sleeve positioning tool are in close contact, and a wedge-shaped sealing ring is installed between them. A liquid outlet gap is left between the lower end face of the sliding switch and the lower end face of the filling port, so that the sliding switch is equivalent to a piston and the sliding sleeve positioning tool is equivalent to a piston sleeve. A lower sealing ring is provided between the contact surface of the retaining sleeve and the base tube.

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