Open hole horizontal well segmented gravel packing string and method

Abstract

The present invention relates to a segmented gravel packing string and method for an open-hole horizontal well. The packing string comprises an outer string and an inner string, wherein the inner string is disposed within an axial passage of the outer string. The outer string comprises a hanging packer, a packing sleeve, a positioning coupling, a quick-connect device, a first screen, a bypass isolation packer, a bypass shutoff valve, a second screen, an opening device, a third screen, a closing device, a liquid-proof lock sealing cylinder, and a check valve float shoe, which are sequentially connected along the direction of packing material input. The inner string comprises a hanging packer setting device, a diverter sleeve, a packing tool, a packing sleeve opening and closing tool, a positioning device, a flushing pipe, a bypass isolation packer setting tool, a closing tool, a switchable check valve, and an inserted positioning sealing rod, which are sequentially connected along the direction of packing material input. The packing method is implemented using the aforementioned packing string.

Description

Technical Field

[0001] The invention belongs to the field of oilfield horizontal well development and production, and particularly relates to a segmented gravel packing string and method for an open hole horizontal well. Background Art

[0002] High water-cut in openhole horizontal wells is leading to increasingly prominent problems such as difficulty maintaining stable production in mature oilfields and low energy conservation and emission reduction effectiveness. In particular, in high-water-cut horizontal wells, edge and bottom water coning leads to premature water breakthrough, reducing the reservoir's water-free production period and recovery rate, severely impacting the well's lifecycle and making remediation challenging. Segmented gravel packing in horizontal wells is a recognized effective method for controlling edge and bottom water coning, improving oil recovery, and extending the well's lifecycle. The segmented gravel packing process string for openhole horizontal wells not only gravels the entire openhole water section but also effectively isolates the horizontal section, filling a gap in domestic sand control completion technology.

[0003] Currently, there are two main segmented gravel packing technologies for openhole horizontal wells. One involves continuous packing with a packer. This involves using a water control screen combined with ultra-light ceramsite sand. By filling the annulus with ultra-light ceramsite, the ultra-light ceramsite reduces channeling of produced fluids outside the pipe. Combined with the water control screen, the high-permeability water-seepage zone is reduced, while the production pressure differential in the low-permeability pay zone is increased, achieving subdivided flow and water control across the entire well section. The main disadvantages of this technology include the high cost of using ultra-light ceramsite and water control screens throughout the entire packing process. Due to the structural limitations of the water control screen, the entire packing process can only be performed with ultra-light ceramsite sand at low flow rates. This results in high pressure, a long time, and significant operational risks. Using an ultra-light ceramsite packer as the packer body, due to its inherent spherical, low-density structure and limited permeability, cannot achieve 100% effective separation of the openhole horizontal section.

[0004] Another method is to use an openhole packer in conjunction with a reverse packing tool to perform segmented gravel packing in openhole horizontal wells. This involves first lowering the screen, openhole packer, and packing sleeve into the wellbore. After the openhole packer is set by the openhole packer setting tool with pressure applied to the pipe, the openhole packer setting tool is removed, and the packing service tool is lowered to connect the packing sleeve. Reverse packing is then performed, starting from the bottom of the horizontal section and working upwards. The entire packing process requires connecting multiple packing tools and running two pipe strings. Gravel packing, backwashing, and closing the packing sleeves are performed segment by segment. This is a cumbersome and time-consuming process. Furthermore, the need to repeatedly close multiple packing tools creates a high risk of sand jamming.

[0005] 2. Technical issues to be resolved:

[0006] 1) Traditional water control screens are used in combination with ultra-light ceramsite for segmented gravel packing of openhole horizontal wells. Ultra-light ceramsite is used as a packer in the horizontal section. However, due to its inherent structural characteristics of spherical, low-density ceramsite sand and limited permeability, it cannot effectively separate the openhole horizontal section.

[0007] 2) Due to the structural limitations of the open-hole packer and reverse packing tool, the string must be run twice, and gravel packing and backwashing can only be performed in sections. During this process, multiple packing sleeves need to be opened and closed. The operation process is complicated, the operation time is long, and the operation risk is high.

[0008] 3. Causes of the problem:

[0009] 1) Problems with traditional string connection methods and string structure. Due to the inherent permeability of ultra-light ceramsite, using ultra-light ceramsite for annular filling as a horizontal section sealer, and combining the water control screen with the ultra-light ceramsite filling process, cannot effectively seal the open hole horizontal section.

[0010] 2) Due to the structural limitations of the open-hole packer and reverse packing tool, the string needs to be lowered twice, and gravel packing and backwashing can only be performed in sections. During this period, multiple packing sleeves need to be opened and closed. The operation process is complicated and the operation time is long. At the same time, the operation risk is high, which cannot meet the efficient requirements of one-time string running and one-time filling operation. Summary of the Invention

[0011] In order to solve all or part of the above problems, the present invention aims to provide a segmented gravel packing string and method for open hole horizontal wells, which can run the packing string into the open hole oil well at one time to perform multiple process operations such as setting, filling, cleaning, and breaking.

[0012] According to a first aspect of the present invention, there is provided a segmented gravel pack string for an open hole horizontal well, comprising an outer string and an inner string, wherein the inner string is disposed in an axial passage of the outer string;

[0013] The outer string includes a hanging packer, a packing sleeve, a positioning coupling, a quick-connect device, a first screen, a bypass isolation packer, a bypass shutoff valve, a second screen, an opening device, a third screen, a closing device, a liquid-proof lock sealing cylinder, and a check valve float shoe, which are connected in sequence along the direction of filling material input (from top to bottom in the figure);

[0014] The inner tubing string includes a hanging packer setting device, a diverter sleeve, a filling tool, a filling sleeve switching tool, a positioning device, a flushing pipe, a bypass isolation packer setting tool, a closing tool, a switchable check valve, and an inserted positioning sealing rod, which are connected in sequence along the direction of filling material input (from top to bottom in the figure).

[0015] According to a second aspect of the present invention, a method for segmented gravel packing in an open hole horizontal well is provided, which is implemented by the above-mentioned segmented gravel packing string for an open hole horizontal well, comprising:

[0016] Step 1: Assemble the inner and outer tubing strings together and fix them relatively, connect the inner tubing string to the drill pipe, and then lower the outer and inner tubing strings into the oil well, while using mud flow to flush the remaining mud and sand in the open hole horizontal section;

[0017] Step 2: Setting the suspension packer by the suspension packer setting device, so that the suspension packer fixes the outer tubing string at a predetermined position in the oil well;

[0018] Step 3, releasing the relative fixed state of the inner and outer tubing strings by applying a predetermined pressure to the inner tubing string or rotating the inner tubing string;

[0019] Step 4, checking the fixed state of the suspension packer in the oil well by applying a predetermined pressure to the suspension packer;

[0020] Step 5: Lift the inner tubing string to a predetermined height and close the switchable check valve via the closing device in the outer tubing string;

[0021] Step 6: Continue to lift the inner string to a predetermined height to reach the filling position, and set the bypass isolation packer using the isolation packer setting tool;

[0022] Step 7, gravel packing, wherein the sand solution is fed into the open hole horizontal section through the inner and outer tubing strings, the filling sand is filtered and fills the wellbore annulus of the open hole horizontal section, and the return fluid is output from the oil well through the outer and inner tubing strings;

[0023] Step 8: Clean the excess mortar in the inner tubing string with well washing fluid;

[0024] Step 9: injecting a gel-breaking liquid into the open hole horizontal section through the inner and outer tubing strings to dissolve the mud cake on the wellbore wall;

[0025] Step 10: lift the inner tubing string, close the interlayer passage of the bypass shut-off valve by using a closing tool, and the inner tubing string is separated from the axial passage of the outer tubing string and taken out of the oil well.

[0026] As can be seen from the above technical solutions, the present invention provides a segmented gravel packing string and method for open hole horizontal wells, which has the following beneficial effects:

[0027] The present invention adds a sealing mechanism, a circulation mechanism, and a single-closing mechanism to the inner tubing string, and cooperates with the outer tubing string at the same time, thereby effectively ensuring a positive circulation channel for the entire tubing string, realizing the horizontal well open hole gravel filling process, ensuring operation safety, and improving the recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 and Figure 2 This is a schematic diagram of the status of the tubing string when the steel ball is dropped to set and suspend the packer;

[0029] Figure 3 and Figure 4 This is a schematic diagram of the status of the tubing string when the bypass isolation packer is set;

[0030] Figure 5 and Figure 6 This is a schematic diagram of the status of the pipe string during gravel packing;

[0031] Figure 7 and Figure 8 This is a schematic diagram of the status of the pipe string during reverse circulation to clean excess mortar;

[0032] Figure 9 and Figure 10 Schematic diagram of the column status when displacing the gel breaking liquid.

[0033] The numbers in the figure are: 100, casing; 200, drill pipe;

[0034] 1. Hanging packer setting tool; 2. Hanging packer; 3. Diverter sleeve; 4. Filling sleeve; 5. Filling tool; 6. Filling sleeve opening and closing tool; 7. Positioning coupling; 8. Positioning device; 9. Quick connection device; 10. Punch pipe; 11. Screen pipe; 11-1. First screen pipe; 11-2. Second screen pipe; 11-3. Third screen pipe; 12. Bypass isolation packer setting tool; 13. Bypass isolation packer; 14. Bypass closing valve; 15. Closing tool; 16. Opening device; 17. Closing device; 18. Switchable check valve; 19. Liquid-proof lock sealing cylinder; 20. Insertion of positioning sealing rod; 21. Check valve type float shoe. DETAILED DESCRIPTION

[0035] In order to better understand the purpose, structure and function of the present invention, the following further describes in detail an open hole horizontal well segmented gravel packing string and method of the present invention in conjunction with the accompanying drawings.

[0036] Example 1

[0037] like Figure 1 As shown, an oil well is drilled in the formation, and a casing 100 has been installed in the oil well to support the well wall of the oil well.

[0038] like Figure 1-10 As shown, an embodiment of the present invention provides a segmented gravel packing string for an open hole horizontal well, comprising an outer string and an inner string, wherein the inner string is arranged in an axial channel of the outer string;

[0039] The outer string includes a hanging packer 2, a packing sleeve 4, a positioning coupling 7, a quick-connect device 9, a first screen 11-1, a bypass isolation packer 13, a bypass shutoff valve 14, a second screen 11-2, an opening device 16, a third screen 11-3, a closing device 17, a liquid-proof lock sealing cylinder 19, and a check valve float shoe 21, which are connected in sequence along the direction of filling material input (from top to bottom in the figure);

[0040] The inner tubing string includes a hanging packer sealing device 1, a diverter sleeve 3, a filling tool 5, a filling sleeve switching tool 6, a positioning device 8, a flushing pipe 10, a bypass isolation packer sealing tool 12, a closing tool 15, a switchable check valve 18, and an inserted positioning sealing rod 20, which are connected in sequence along the direction of filling material input (the direction is from top to bottom in the figure).

[0041] The multiple components in the outer tubular string can be threadedly connected in sequence, and the multiple components in the inner tubular string can be threadedly connected in sequence.

[0042] The above-mentioned screen tubes (the first screen tube 11-1, the second screen tube 11-2, and the third screen tube 11-3) include but are not limited to ordinary precision screen tubes, ordinary wire-wound screen tubes, and the like.

[0043] In one embodiment, multiple sets of bypass isolation packers 13 and bypass closing valves 14 are provided in the outer tubing string, and multiple sets of bypass isolation packer setting tools 12 are provided in the corresponding inner tubing string. The multiple sets of bypass isolation packers 13 and bypass closing valves 14 can separate the open hole horizontal section into multiple filling areas.

[0044] The process string equipped with multiple sets of bypass isolation packers 13 and bypass closing valves 14 can be lowered into the wellbore at one time to complete the segmented gravel packing of open hole horizontal wells, and can ensure effective separation between each layer, meet the requirements of segmented gravel packing operations in open hole horizontal wells, shorten the operation time, reduce development costs, and ensure safe and reliable operations.

[0045] Example 2

[0046] The embodiment of the present invention further provides a method for segmented gravel packing in an open hole horizontal well, which is implemented by the segmented gravel packing string for an open hole horizontal well described in Example 1, comprising:

[0047] Step 1: Assemble the inner and outer tubing strings together and fix them relatively, connect the inner tubing string to the drill pipe 200, and then lower the outer and inner tubing strings into the oil well, while using mud flow to flush the remaining mud and sand in the open hole horizontal section;

[0048] Step 2: Setting the suspension packer 2 by the suspension packer setting device 1, and the suspension packer 2 fixes the outer tubing string at a predetermined position in the oil well;

[0049] Step 3, releasing the relative fixed state of the inner and outer tubing strings by applying a predetermined pressure to the inner tubing string or rotating the inner tubing string;

[0050] Step 4, checking the fixed state of the suspension packer 2 in the oil well by applying a predetermined pressure to the suspension packer 2;

[0051] Step 5: Lift the inner tubular string to a predetermined height and close the switchable check valve 18 via the closing device 17 in the outer tubular string;

[0052] Step 6: Continue to lift the inner string to a predetermined height to reach the filling position, and set the bypass isolation packer 13 by the isolation packer setting tool 12;

[0053] Step 7, gravel packing, wherein the sand solution is fed into the open hole horizontal section through the inner and outer tubing strings, the filling sand is filtered and fills the wellbore annulus of the open hole horizontal section, and the return fluid is output from the oil well through the outer and inner tubing strings;

[0054] Step 8: Clean the excess mortar in the inner tubing string with well washing fluid;

[0055] Step 9: injecting a gel-breaking liquid into the open hole horizontal section through the inner and outer tubing strings to dissolve the mud cake on the wellbore wall;

[0056] Step 10: lift the inner tubing string and close the interlayer passage of the bypass closing valve 14 by means of the closing tool 15. The inner tubing string is separated from the axial passage of the outer tubing string and is taken out of the oil well.

[0057] The inner and outer tubing strings are assembled and fixed, which can be achieved through the hanging packer setting device 1 and the setting hanging packer 2. The connection parts of the two are usually provided with multiple release pins. The subsequent release of the inner and outer tubing strings can also be achieved through the hanging packer setting device 1 and the setting hanging packer 2. The release pins can be cut off by external force to achieve release.

[0058] In one embodiment, in step 1, the mud flows sequentially through the drill pipe 200, the suspension packer setting device 1, the diverter sleeve 3, the filling tool 5, the filling sleeve switching tool 6, the positioning device 8, the flushing pipe 10, the bypass isolation packer setting tool 12, the closing tool 15, the switchable check valve 18, the inserted positioning sealing rod 20, the check valve type float shoe 21, and the wellbore annulus and returns to the outside of the well. During the running process, the mud can be flushed out of the open hole horizontal section to ensure that the pipe string is smoothly lowered into place. After the pipe string is lowered into place, the mud displacement is completed.

[0059] The switchable check valve 18 remains open during the lowering process, and liquid can flow up and down inside it.

[0060] In one embodiment, in step 2: the inner and outer tubular strings are kept in a free hanging weight state, and the setting position of the suspension packer setting device 1 is set away from the coupling position of the casing 100. A first-level setting ball (a steel ball with a diameter of 45 mm can be selected) is dropped into the drill pipe 200 through the wellhead. The setting ball lands on the ball seat position of the packing tool 5 and blocks the positive circulation channel. The drill pipe 200 is positively pressurized to set the suspension packer 2.

[0061] In step 3: the setting state of the suspension packer 2 is checked by operating the wellhead drill pipe 200 to lift and lower a certain tonnage;

[0062] Keep the inner tubing string in a downward pressure state, pressurize the drill pipe 200 to the set pressure, release the pressure to zero after stabilizing the pressure for a predetermined time (for example, 10 minutes), lift the drill pipe 200 to complete the release of the inner and outer tubing strings, or directly rotate the drill pipe 200 forward for a certain number of turns and lift the inner tubing string to complete the release of the inner and outer tubing strings.

[0063] In one embodiment, in step 4: the inner layer tubing is lifted to a set height, and a certain pressure is applied to the annulus between the drill pipe 200 and the casing 100. At this time, the external vulcanized sealing ring of the filling tool 5 is sealed with the central pipe of the suspension packer 2, and the rubber tube of the suspension packer 2 is sealed with the inner wall of the casing 100. The pressure is stabilized for a predetermined time (for example, 15 minutes), and it is required that there is no pressure drop or the pressure drop value is not greater than 1% of the set pressure value. If there is no pressure drop or the pressure drop value is not greater than 1% of the set pressure value, it means that the rubber tube of the suspension packer (2) is well expanded and sealed.

[0064] In one embodiment, in step 5: continue to lift the inner tubing string to a set height, so that the switchable one-flow valve 18 in the inner tubing string passes over the closing device 17 in the outer tubing string, and the switchable one-flow valve 18 is closed in one direction through the closing device 17. At this time, the switchable one-flow valve 18 allows the liquid to flow from the lower part to the upper part, but does not allow the liquid to flow from the upper part to the lower part.

[0065] In one embodiment, in step 6: the inner tubing string is continuously lifted to a set height, so that the positioning device 8 in the inner tubing string passes over the positioning coupling 7 in the outer tubing string, and the inner tubing string is lowered so that the positioning device 8 and the positioning coupling 7 are aligned, and this position is marked as the filling position. At this time, the bypass isolation packer setting tool 12 is located at the setting position of the bypass isolation packer 13;

[0066] The annulus between the drill pipe 200 and the casing 100 is positively pressurized to the set pressure value and maintained at a predetermined pressure for a predetermined time (e.g., 15 minutes). The pressure-transmitting fluid flows in sequence through the annulus between the drill pipe 200 and the casing 100, the interlayer channel of the filling tool 5, the flushing pipe 10, the bypass isolation packer sealing tool 12, the closing tool 15, and the upper part of the switchable check valve 18, and the pressure is held up in the above space. The set pressure value can enable the bypass isolation packer sealing tool 12 to complete the sealing of the bypass isolation packer 13.

[0067] In one embodiment, in step 7: at the filling position, the sand and liquid flow through the drill pipe 200, the hanging packer setting tool 1, the diverter sleeve 3, the filling tool 5, the filling sleeve 4, the quick connection device 7, the first screen pipe 11-1 and the well wall annulus, the interlayer channel of the bypass isolation packer 13, the interlayer channel of the bypass closing valve 14, the second screen pipe 11-2 and the well wall annulus in sequence, and the filling sand is filtered by the two groups of screen pipes to fill the annulus between the two groups of screen pipes and the well wall, and the return fluid is returned through the inserted positioning sealing rod 20, the switchable check valve 18, the closing tool 15, the bypass isolation packer setting tool 12, the positioning device 8, the filling sleeve switching tool 6, the interlayer channel of the filling tool 5, the interlayer channel between the inner and outer tubing strings, and the annulus between the drill pipe 200 and the casing 100.

[0068] In one embodiment, in step 8: the inner tubular string is lifted to a set height, and during the lifting of the tubular string, the packing sleeve opening and closing tool 6 closes the packing sleeve 4;

[0069] The well washing fluid is pumped into the annulus between the drill pipe 200 and the casing 100, enters the inner layer tubing string through the filling port of the filling tool 5, and returns to the wellhead through the hanging packer setting tool 1 and the drill pipe 200.

[0070] In one embodiment, in step 9, the inner tubing string is lifted so that the switchable check valve 18 on the inner tubing string passes over the opening device 16 on the outer tubing string. Then, the inner tubing string is lowered so that the switchable check valve 18 on the inner tubing string passes over the opening device 16 on the outer tubing string for the second time. At this time, the switchable check valve 18 is opened by the opening device 16, and liquid can flow up and down inside the switchable check valve 18.

[0071] A second-stage sealing ball (a 60mm diameter steel ball can be selected) is placed from the wellhead drill pipe 200 to the ball seat position inside the diverter sleeve 3. The drill pipe 200 is pressurized to the set pressure value to open the interlayer channel of the diverter sleeve 3.

[0072] The annulus between the wellhead drill pipe 200 and the casing 100 is closed, and a gel-breaking liquid is pumped into the drill pipe 200. The gel-breaking liquid passes through the drill pipe 200, the hanging packer setting tool 1, the diverter sleeve 3, the filling tool 5, the filling sleeve switching tool 6, the positioning device 8, the flushing pipe 10, the bypass isolation packer setting tool 12, the closing tool 15, the switchable check valve 18, and the inserted positioning sealing rod 20, and is pumped out. The liquid passes through the third screen pipe 11-3, the second screen pipe 11-2, and the first screen pipe 11-1 and is squeezed into the formation to dissolve the mud cake on the wellbore wall.

[0073] The breaking fluid is squeezed into the formation through all the screens. During step 9, the annulus between the drill pipe 200 and the casing 100 is closed. The breaking fluid pumped from the inserted positioning sealing rod 20 fills the annulus between the inner and outer tubing strings. The breaking fluid can only enter the formation through the screens provided in the outer tubing string. Although the inserted positioning sealing rod 20 is located inside the third screen 11-3 during step 9, the breaking fluid enters the formation through all the screens.

[0074] In one embodiment, in step 10: during the pulling out process, the closing tool 15 on the inner tubular string closes the interlayer passage of the bypass closing valve 14 when passing through the bypass closing valve 14 on the outer tubular string, thereby pulling out the inner tubular string.

[0075] The lower joint of the bypass isolation packer 13 and the upper joint of the bypass closing valve 14 are connected together by threads, and the interlayer channels inside the two are interconnected, so closing the interlayer channel inside the bypass closing valve 14 is equivalent to closing the interlayer channel inside the bypass isolation packer 13.

[0076] The present invention can achieve the following: in one trip of running the tubing string, the bypass isolation packer 13 is first sealed before gravel filling, and then the top gravel filling is carried out; after the gravel filling is completed, the interlayer channel of the bypass isolation packer 13 is closed by the closing tool 15 in cooperation with the bypass closing valve 14, which can effectively ensure the effectiveness of the open hole horizontal section separation. The entire tubing string can use ordinary screen pipes and ordinary ceramsite sand for gravel filling, with low operation cost and short operation time, meeting the high-efficiency demand of realizing segmented filling of open hole horizontal wells in one trip of running the tubing string.

[0077] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0078] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, or integration; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for gravel packing an open hole horizontal well, comprising: using an open hole horizontal well segmented gravel packing string; the open hole horizontal well segmented gravel packing string comprising an outer string and an inner string, the inner string being disposed within an axial passage of the outer string; The outer tubular string comprises a hanging packer (2), a filling sleeve (4), a positioning collar (7), a quick connection device (9), a first screen (11-1), a bypass isolation packer (13), a bypass closing valve (14), a second screen (11-2), an opening device (16), a third screen (11-3), a closing device (17), a liquid-proof lock sealing cylinder (19), and a check valve type floating shoe (21), which are sequentially connected along the filling material input direction. The inner string comprises a hanging packer setting device (1), a diverter sleeve (3), a filling tool (5), a filling sleeve switching tool (6), a positioning device (8), a flushing pipe (10), a bypass isolation packer setting tool (12), a closing tool (15), a switchable check valve (18), and an insert positioning sealing rod (20) connected in sequence along the filling material input direction; The outer tubing string is provided with a plurality of bypass isolation packers (13) and bypass closing valves (14), and the corresponding inner tubing string is provided with a plurality of bypass isolation packer setting tools (12), and the open hole horizontal section is divided into a plurality of filling areas by the plurality of bypass isolation packers (13) and bypass closing valves (14); It is characterized in that The staged gravel packing method for openhole horizontal wells includes: Step 1: Assemble the inner and outer tubular strings together and fix them relatively, connect the inner tubular string to the drill pipe (200), and then lower the outer and inner tubular strings into the oil well, while using mud flow to flush the remaining mud and sand in the open hole horizontal section; Step 2, setting the suspension packer (2) by the suspension packer setting device (1), and the suspension packer (2) fixes the outer tubing string at a predetermined position in the oil well; Step 3, releasing the relative fixed state of the inner and outer tubing strings by applying a predetermined pressure to the inner tubing string or rotating the inner tubing string; Step 4, checking the fixed state of the suspension packer (2) in the oil well by applying a predetermined pressure to the suspension packer (2); Step 5: lifting the inner tubular string to a predetermined height and closing the switchable check valve (18) via the closing device (17) in the outer tubular string; Step 6, continue to lift the inner string to a predetermined height to reach the filling position, and set the bypass isolation packer (13) by the bypass isolation packer setting tool (12); Step 7, gravel packing, wherein the sand solution is fed into the open hole horizontal section through the inner and outer tubing strings, the filling sand is filtered and fills the wellbore annulus of the open hole horizontal section, and the return fluid is output from the oil well through the outer and inner tubing strings; Step 8: Clean the excess mortar in the inner tubing string with well washing fluid; Step 9: injecting a gel-breaking liquid into the open hole horizontal section through the inner and outer tubing strings to dissolve the mud cake on the wellbore wall; Step 10, lifting the inner tubing string, closing the interlayer passage of the bypass closing valve (14) by means of a closing tool (15), and the inner tubing string is separated from the axial passage of the outer tubing string and removed from the oil well; In the step 7, at the filling position, the sand and liquid flow sequentially through the drill pipe (200), the suspension packer setting device (1), the diversion sleeve (3), the filling tool (5), the filling sleeve (4), the quick connection device (9), the first screen pipe (11-1) and the wellbore annulus, the interlayer channel of the bypass isolation packer (13), the interlayer channel of the bypass closing valve (14), the second screen pipe (11-2) and the wellbore annulus, the filling sand is filtered through the two groups of screen pipes to fill the annulus between the two groups of screen pipes and the wellbore, and the return fluid is returned through the inserted positioning sealing rod (20), the switchable check valve (18), the closing tool (15), the bypass isolation packer setting tool (12), the positioning device (8), the filling sleeve switching tool (6), the interlayer channel of the filling tool (5), the interlayer channel between the inner and outer tubular strings, and the annulus between the drill pipe (200) and the casing (100).

2. The method for segmented gravel packing of open hole horizontal wells according to claim 1, characterized in that: In step 1, the mud flow sequentially passes through the drill pipe (200), the suspension packer setting device (1), the diverter sleeve (3), the filling tool (5), the filling sleeve switching tool (6), the positioning device (8), the flushing pipe (10), the bypass isolation packer setting tool (12), the closing tool (15), the switchable check valve (18), the inserted positioning sealing rod (20), the check valve type floating shoe (21), and the wellbore annulus to return to the outside of the well, and the residual mud and sand in the open hole horizontal section can be flushed during the running process; The switchable check valve (18) remains open during the lowering process, and liquid can flow up and down inside it.

3. The method for segmented gravel packing of open hole horizontal wells according to claim 1, characterized in that: In step 2: the inner and outer tubular strings are kept in a free hanging weight state, and the setting position of the suspension packer setting device (1) is made to avoid the coupling position of the casing (100), and a first-level setting ball is dropped into the drill pipe (200) through the wellhead, and the first-level setting ball falls on the ball seat position of the filling tool (5) and blocks the positive circulation channel, and the drill pipe (200) is positively pressurized to set the suspension packer (2); In step 3: the setting state of the suspension packer (2) is checked by operating the wellhead drill pipe (200) to lift and lower it to a certain tonnage; The inner tubular string is kept in a downward pressure state, the drill pipe (200) is pressurized to a set pressure, the pressure is released to zero after a predetermined time, and the drill pipe (200) is lifted to complete the release of the inner and outer tubular strings, or the drill pipe (200) is directly rotated forward for a certain number of turns and the inner tubular string is lifted to complete the release of the inner and outer tubular strings.

4. The method for segmented gravel packing of open hole horizontal wells according to claim 1, characterized in that: In the step 4, the inner layer pipe string is lifted to a set height, and a certain pressure is applied to the annulus between the drill pipe (200) and the casing (100). At this time, the external vulcanized sealing ring of the filling tool (5) is sealed with the central pipe of the hanging packer (2), and the rubber tube of the hanging packer (2) is sealed with the inner wall of the casing (100). The pressure is stabilized for a predetermined time, and it is required that there is no pressure drop or the pressure drop value is not greater than 1% of the set pressure value. In step 5, the inner tubular column is continuously lifted to a set height, so that the switchable check valve (18) in the inner tubular column passes over the closing device (17) in the outer tubular column, and the switchable check valve (18) is closed in one direction by the closing device (17). At this time, the switchable check valve (18) allows the liquid to flow from the lower part to the upper part, but does not allow the liquid to flow from the upper part to the lower part.

5. The method for segmented gravel packing of open hole horizontal wells according to claim 1, characterized in that: In step 6: the inner tubular string is continuously lifted to a set height, so that the positioning device (8) in the inner tubular string passes over the positioning collar (7) in the outer tubular string, and the inner tubular string is lowered so that the positioning device (8) and the positioning collar (7) are positioned, and the position is marked as the filling position, and at this time, the bypass isolation packer setting tool (12) is located at the setting position of the bypass isolation packer (13); The annulus between the drill pipe (200) and the casing (100) is pressurized to a set pressure value and maintained at a predetermined pressure for a predetermined time. The pressure-transmitting fluid flows sequentially through the annulus between the drill pipe (200) and the casing (100), the interlayer channel of the filling tool (5), the flushing pipe (10), the bypass isolation packer setting tool (12), the closing tool (15), and the upper part of the switchable check valve (18), and the pressure is held in the above space. The set pressure value can enable the bypass isolation packer setting tool (12) to complete the setting of the bypass isolation packer (13).

6. The method for segmented gravel packing of open hole horizontal wells according to claim 1, characterized in that: In step 8: the inner layer pipe string is lifted to a set height, and during the lifting of the pipe string, the filling sleeve opening and closing tool (6) closes the filling sleeve (4); The well washing fluid is pumped into the annulus between the drill pipe (200) and the casing (100), enters the inner layer tubing string through the filling port of the filling tool (5), and returns to the wellhead through the hanging packer setting device (1) and the drill pipe (200).

7. The method for segmented gravel packing of open hole horizontal wells according to claim 1, characterized in that: In step 9, the inner tubing string is lifted up so that the switchable check valve (18) on the inner tubing string passes over the opening device (16) on the outer tubing string, and then the inner tubing string is lowered so that the switchable check valve (18) on the inner tubing string passes over the opening device (16) on the outer tubing string for the second time. At this time, the switchable check valve (18) is opened by the opening device (16), and liquid can flow up and down inside the switchable check valve (18); A second-stage sealing ball is placed from the wellhead drill pipe (200) to the ball seat position inside the diverter sleeve (3), and the drill pipe (200) is pressurized to a set pressure value to open the interlayer channel of the diverter sleeve (3); The annulus between the wellhead drill pipe (200) and the casing (100) is closed, and a gel-breaking liquid is pumped into the inside of the drill pipe (200). The gel-breaking liquid passes through the drill pipe (200), the suspension packer setting device (1), the diverter sleeve (3), the filling tool (5), the filling sleeve switching tool (6), the positioning device (8), the flushing pipe (10), the bypass isolation packer setting tool (12), the closing tool (15), the switchable check valve (18), and the inserted positioning sealing rod (20) and is pumped out. The liquid passes through the third screen pipe (11-3), the second screen pipe (11-2), and the first screen pipe (11-1) and is squeezed into the formation to dissolve the mud cake on the well wall.

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