Double-seal one-way valve for concentric double-pipe reverse circulation well drilling and well drilling method

Abstract

The invention discloses a double-seal one-way valve for concentric double-pipe reverse circulation well drilling and a well drilling method. The one-way valve comprises a body, an upper inner pipe, an upper valve element shaft and a lower valve element shaft, a lower valve seat is arranged between the lower valve element shaft and the body, and a reset spring is arranged below the lower valve element shaft. The upper inner pipe is provided with an upper central flow channel, the lower valve core shaft is provided with a lower central flow channel, and an annular flow channel is arranged among the upper inner pipe, the upper valve core shaft and the body; a lower annulus is arranged between the lower valve core shaft and the body; under the action of liquid pressure of the upper center flow channel and the annular flow channel, the upper valve element shaft and the lower valve element shaft move downwards, the upper center flow channel is communicated with the external environment through an inner channel outer flow guide hole of the body, and the annular flow channel is communicated with the lower center flow channel through an annular flow guide hole in the lower annular flow channel and an annular flow guide hole in the lower valve element shaft; and after no liquid pressure effect exists, the upper valve element shaft and the lower valve element shaft move upwards under the effect of the reset spring, so that the inner channel and the outer channel are closed. Downhole double-channel automatic synchronous opening and closing can be achieved, and operation reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling, and particularly to a double-sealing one-way valve and a drilling method for concentric dual-tube reverse circulation drilling. Background Art

[0002] In recent years, the exploration and development efforts of shale oil, shale gas, tight oil, tight gas, etc. have been continuously increasing. The development of these oil and gas resources basically applies horizontal wells, supplemented by large-scale fracturing in the later stage. However, horizontal well development has problems such as difficult extension of the horizontal section, difficult cuttings carrying in the inclined well section, and high pump pressure in long horizontal section horizontal wells.

[0003] Concentric dual-tube reverse circulation drilling, also known as double-wall reverse circulation drilling, uses double-wall drill pipes as the main circulation system. It can enable cuttings to quickly enter the central water eye of the double-wall drilling, avoiding or reducing the repeated crushing of cuttings and extending the service life of the drill bit. In addition, since the cuttings are quickly carried out to the ground, they are less polluted by drilling fluid and formation fluids, the logging data is more real, and the formation judgment is more accurate. The cuttings cleaning ability of the double-wall reverse circulation drilling technology has been greatly improved, avoiding the formation of cuttings beds in the inclined well section and horizontal section, reducing the friction resistance of the drill string, and ensuring the smooth extension of the horizontal wellbore. A sliding piston system is added to the double-wall reverse circulation drilling system, reducing the amount of drilling fluid used and effectively reducing the drilling fluid cost. The sliding piston system can also assist the drill bit to apply bottom hole drilling pressure, effectively increasing the extension length of the horizontal wellbore.

[0004] The double-wall reverse circulation drilling technology uses double-wall drill tools with two channels inside. Conventional drill string cocks or downhole check valves only have a single channel and cannot meet the requirements for opening and closing control of the two channels. Currently, the on-site solution is to install a double-channel annular check valve downhole and a double-channel single-sealing cock at the wellhead. Summary of the Invention

[0005] In the double-wall reverse circulation drilling technology, installing a double-channel annular check valve downhole and a double-channel single-sealing cock at the wellhead to achieve the opening and closing control of the two channels. This solution not only requires installing tools downhole and at the wellhead respectively and cannot achieve automatic full sealing, but also the double-channel single-sealing cock used to close the central water eye is located at the wellhead. Once a well kick or blowout occurs, it cannot be controlled in time, with relatively high risks and unable to ensure the safety of drilling.

[0006] In view of the above problems, the present invention is proposed to provide a double-sealing one-way valve and a drilling method for concentric dual-tube reverse circulation drilling that overcome or at least partially solve the above problems.

[0007] In a first aspect, an embodiment of the present invention provides a double-sealing one-way valve for concentric dual-tube reverse circulation drilling, which is characterized in that it includes: a body, an upper inner tube, an upper valve core shaft, and a lower valve core shaft that are sequentially connected within the body; a lower valve seat is provided between the lower valve core shaft and the body, and a return spring is provided below the lower valve core shaft;

[0008] The upper inner tube is provided with an upper central flow channel, the lower valve core shaft is provided with a lower central flow channel, and an annular flow channel is provided between the upper inner tube, the upper valve core shaft and the body; a lower annulus is provided between the lower valve core shaft and the body;

[0009] Under the action of the liquid pressure in the upper central flow channel and the annular flow channel, the upper valve core shaft and the lower valve core shaft move downward, the upper central flow channel is communicated with the external environment through the inner channel external diversion holes on the body, and the annular flow channel is communicated with the lower central flow channel through the lower annulus and the annular diversion holes on the lower valve core shaft;

[0010] After the liquid pressure action stops, the upper valve core shaft and the lower valve core shaft move upward under the action of the return spring, closing the inner channel and the outer channel.

[0011] In some alternative embodiments, the body includes an upper body and a lower body;

[0012] The upper inner tube and the upper valve core shaft are installed in the through hole of the upper body, the upper end of the lower valve core shaft is installed in the upper body through the lower valve seat, and the lower end of the lower valve core shaft is installed in the through hole of the lower body and a return spring is provided in the through hole.

[0013] In some alternative embodiments, the upper end of the upper body is provided with a drill pipe thread to connect the outer tube of the concentric dual-tube drill tool, and the lower end is provided with a drill pipe thread to connect the lower body; the lower end of the lower body is provided with a drill pipe thread to connect the lower drill tool.

[0014] In some alternative embodiments, a retaining ring is provided in the annular hole between the upper inner tube and the upper body, and the retaining ring is provided with a through-flow hole for communicating the annular flow channel.

[0015] In some alternative embodiments, the body is provided with an outer channel diversion hole and an outer channel cavity, and the annulus between the body and the upper inner tube, the outer channel diversion hole, the outer channel cavity, and the annulus between the body and the upper valve core shaft are communicated to form an annular flow channel;

[0016] The outer channel diversion holes and the inner channel external diversion holes are arranged circumferentially and evenly, and the outer channel diversion holes and the inner channel external diversion holes are arranged crosswise.

[0017] In some alternative embodiments, the lower valve core shaft is provided with an upper connection hole to connect the lower end of the upper valve core shaft;

[0018] The lower end of the lower spool shaft has a through hole as the lower central flow channel, and a plurality of annular space diversion holes are circumferentially and evenly arranged on the side wall of the lower central flow channel.

[0019] In some alternative embodiments, the upper end of the lower spool shaft is provided with a first conical surface, and a second conical surface is provided in the through hole of the lower valve seat. The first conical surface and the second conical surface are matched to achieve sealing.

[0020] In some alternative embodiments, the lower spool shaft is coaxially arranged with the upper spool shaft, and a connecting sleeve is provided between the lower spool shaft and the upper spool shaft.

[0021] An embodiment of the present invention provides an application of the above-mentioned double-sealing one-way valve for concentric dual-tube reverse circulation drilling in concentric dual-tube reverse circulation drilling.

[0022] An embodiment of the present invention provides a concentric dual-tube reverse circulation drilling method, which is characterized in that it is realized by using the above-mentioned double-sealing one-way valve for concentric dual-tube reverse circulation drilling. The method includes:

[0023] Connect the outer tube of the concentric dual-tube through the upper body, and connect the inner tube of the concentric dual-tube to the inner tube;

[0024] After the liquid in the inner tube enters the upper central flow channel and the liquid in the outer tube enters the annular space flow channel, under the action of the liquid pressure in the upper central flow channel and the annular space flow channel, the upper spool shaft and the lower spool shaft move downward. The upper central flow channel is communicated with the external environment through the inner channel external diversion holes on the body, and the annular space flow channel is communicated with the lower central flow channel through the lower annular space and the annular space diversion holes on the lower spool shaft; thus, the inner and outer channels of the concentric dual-tube are opened together;

[0025] After the action of the liquid pressure disappears, the upper spool shaft and the lower spool shaft move upward under the action of the return spring, so that the inner channel and the outer channel are closed together.

[0026] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0027] The double-sealing one-way valve for concentric dual-tube reverse circulation drilling provided by the embodiments of the present invention controls the synchronous movement of the upper valve core shaft and the lower valve core shaft through the central flow channel and the annulus flow channel, realizes the synchronous control of the simultaneous opening and closing of the two channels of the concentric dual-tube, and through the design of the double valve seats and the integral valve core shaft, realizes the control of the opening or closing of the two downhole channels only by changing the start and stop of the pump on the ground, realizes the automatic synchronous switching of the two downhole channels, improves the reliability of the operation, and improves the on-site operation efficiency and safety. The double-sealing one-way valve can be opened either by the action of the annulus liquid or by the action of the liquid in the central water eye, which is convenient for realizing the conversion of the downhole circulation mode. Its reset mechanism is designed with a reset spring, and when a complex situation occurs downhole resulting in an increase in the bottom liquid pressure, it can also automatically push the double valve core shaft upward to achieve strong closing to ensure downhole safety.

[0028] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in the written specification, claims, and drawings.

[0029] The technical solutions of the present invention will be further described in detail below through the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0031] Figure 1 Schematic structural diagram of the double-channel closed state of the double-sealing one-way valve in the embodiments of the present invention;

[0032] Figure 2 Schematic structural diagram of the double-channel open state of the double-sealing one-way valve in the embodiments of the present invention;

[0033] Figure 3 Schematic structural diagram of the upper double-channel in the embodiments of the present invention;

[0034] Figure 4 Schematic structural diagram of the middle double-channel in the embodiments of the present invention;

[0035] Figure 5 Schematic structural diagram of the lower double-channel in the embodiments of the present invention;

[0036] Figure 6 Flowchart of the operation for realizing the concentric dual-tube reverse circulation drilling method in the embodiments of the present invention.

[0037] Wherein:

[0038] 1. Upper body; 2. Retaining ring; 3. Upper inner tube; 4. Inner tube seal; 5. Upper spool shaft; 6. Upper valve upper seal; 7. Upper valve lower seal; 8. Lower valve seat; 9. Lower valve seat upper seal; 10. Positioning screw pin; 11. Retaining ring for positioning pin; 12. Lower valve seat lower seal; 13. Lower valve seat dynamic seal; 14. Connecting screw sleeve; 15. Upper and lower valve connection seal; 16. Lower spool shaft; 17. Return spring; 18. Lower body; 19. Upper inner channel; 20. Upper outer channel; 21. Outer channel diversion hole; 22. Inner channel outer diversion hole; 23. Outer channel cavity; 24. Lower spool shaft through hole; 25. Lower valve annulus; 26. Annulus diversion hole. Detailed implementation manners

[0039] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0040] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0042] To solve the problems existing in the prior art and ensure the safety of drilling, an embodiment of the present invention provides a double-seal one-way valve for concentric dual-tube reverse circulation drilling. The one-way valve is an integrated downhole double-seal one-way valve for concentric dual-tube reverse circulation drilling, which can realize the synchronous opening or closing of the two channels inside and outside the concentric dual-tubes only by changing the on-off of the pump on the ground, achieving the synchronous control of the dual channels, simplifying the control procedure for opening or closing the dual channels of concentric dual-tube drilling, realizing the automatic synchronous switching of the downhole dual channels, ensuring the safety of drilling, and improving the reliability of drilling operations and the on-site operation efficiency.

[0043] An embodiment of the present invention provides a double-seal one-way valve for concentric dual-tube reverse circulation drilling. The schematic structural diagram in its closed state is as Figure 1 shown, and the structure in the open state is as Figure 2 shown. The one-way valve includes:

[0044] A body, an upper inner tube 3, an upper valve core shaft 5, and a lower valve core shaft 16 that are sequentially connected inside the body; a lower valve seat 8 is provided between the lower valve core shaft 16 and the body, and a return spring 17 is provided below the lower valve core shaft.

[0045] The upper inner tube 3 is provided with an upper central flow channel, the lower valve core shaft 16 is provided with a lower central flow channel, and an annular flow channel is provided between the upper inner tube 3, the upper valve core shaft 5, and the body; a lower annulus is provided between the lower valve core shaft 16 and the body;

[0046] Under the action of the liquid pressure in the upper central flow channel and the annular flow channel, the upper valve core shaft 5 and the lower valve core shaft 16 move downward, and the upper central flow channel is communicated with the external environment through the inner channel external diversion hole 22 on the body, and the annular flow channel is communicated with the lower central flow channel through the lower annulus and the annular diversion hole 26 on the lower valve core shaft;

[0047] After the liquid pressure action disappears, the upper valve core shaft 5 and the lower valve core shaft 16 move upward under the action of the return spring 17 to close the inner channel and the outer channel.

[0048] In some optional embodiments, the above-mentioned body includes: an upper body 1 and a lower body 18; wherein, the inner part of the upper end of the upper body 1 is designed with a drill pipe thread to connect the outer pipe of the concentric dual-tube drill tool, and can be connected to the lower end of the upper concentric dual-tube drill tool outer pipe. The lower end is designed with a drill pipe thread to connect the lower body and can be connected to the upper end of the lower body 18. The lower end of the lower body 18 is provided with a drill pipe thread to connect the lower drill tool, and the upper body 1 and the lower body 18 form the body.

[0049] A retaining ring 2 is provided in the annular hole between the upper inner tube and the upper body, and the retaining ring 2 is provided with a through-flow hole for communicating the annular flow channel. The retaining ring 2 can be a positioning retaining ring for positioning the upper inner tube 3 and the upper body 1

[0050] Optionally, the upper inner tube 3 and the upper valve core shaft 5 are installed in the through hole of the upper body 1. The upper end of the lower valve core shaft 16 is installed in the upper body 1 through the lower valve seat 8, and the lower end of the lower valve core shaft 16 is installed in the through hole of the lower body 18, and a return spring 17 is provided in the through hole. A through hole 24 of the lower valve core shaft may also be provided on the lower valve core shaft.

[0051] The body is provided with an outer channel diversion hole 21 and an outer channel cavity 23. The annulus between the body and the upper inner tube 3, the outer channel diversion hole 21, the outer channel cavity, and the annulus between the body and the upper valve core shaft 5 are connected to form an annulus flow path. The lower end of the lower valve core shaft 16 has a through hole as the lower central flow path, and a plurality of annulus diversion holes are circumferentially and evenly arranged on the side wall of the lower central flow path.

[0052] In this application, two flow paths, an inner flow path and an outer flow path, are provided. The inner flow path includes the upper central flow path of the upper inner tube 3, the central flow path of the upper body 1, and the inner channel outer diversion hole 22 provided on the upper body 1; the outer flow path is an annulus flow path, including the annulus between the upper body 1 and the upper inner tube 3, the outer channel diversion hole 21 and the outer channel cavity 23 provided on the upper body, the central through hole of the lower valve seat 8, and the annulus between the lower valve core shaft and the upper body 1. The annulus flow path can also be connected to the lower central wellbore through the annulus diversion hole 26.

[0053] For the cross-sectional structure of the dual-channel setting of the annulus flow path and the central flow path, see Figure 3 、 Figure 4 and Figure 5 as shown. Among them:

[0054] Figure 3 is the A-A cross-sectional view, showing the upper dual-channel structure. In the figure, the upper inner channel 19 is the upper central flow path in the upper inner tube 3, and the upper outer channel 20 is the annulus between the upper inner tube 3 and the upper body 1 in this cross-section.

[0055] Figure 4 is the B-B cross-sectional view, showing the middle dual-channel structure. In this cross-section, the middle outer channel is the outer channel diversion hole 21, and the middle inner channel is the upper central flow path in the upper inner tube 3 and the inner channel outer diversion hole 22. Preferably, the outer channel diversion hole 21 and the inner channel outer diversion hole 22 are circumferentially and evenly arranged, and the outer channel diversion hole 21 and the inner channel outer diversion hole 22 are cross-arranged.

[0056] Figure 5 is the C–C cross-sectional view, showing the lower dual-channel structure. In this cross-section, the lower outer channel is the lower valve annulus 25, that is, the annulus between the lower valve core shaft 16 and the upper body 1; the lower inner channel is the annulus diversion hole 26 and the lower central flow path on the lower valve core shaft 16.

[0057] Optionally, an inner tube seal 4 may be provided between the upper inner tube 3 and the upper body 1, and an upper valve upper seal 6 and an upper valve lower seal 7 may be provided between the upper valve spool shaft 5 and the upper body 1. The outer diversion hole 22 of the inner channel is located between the upper valve upper seal 6 and the upper valve lower seal 7.

[0058] In some alternative embodiments, the lower part design further includes a lower valve cavity for installing the lower valve seat 8. The lower valve cavity may be integrally designed with the outer channel cavity. The lower valve seat 8 is inserted into the interior from the lower part of the upper body 1 and fixed by a positioning screw pin 10. After the lower valve spool shaft 16 and the upper valve spool shaft 5 are strung together, they are limited by a connecting sleeve 14 to form the double valve spool shaft of the present invention. A positioning pin circlip 11 is also provided at the positioning screw pin 10.

[0059] In some alternative embodiments, the lower valve spool shaft 16 is provided with an upper connection hole to connect the lower end of the upper valve spool shaft 5. The upper end of the lower valve spool shaft 16 is provided with a first conical surface, and a second conical surface is provided in the through hole of the lower valve seat 8. The first conical surface and the second conical surface are matched to achieve sealing. Preferably, the lower valve spool shaft 16 and the upper valve spool shaft 5 are coaxially arranged, and a connecting sleeve 14 is provided between the lower valve spool shaft and the upper valve spool shaft.

[0060] For the above check valve, the lower valve seat 8 and the upper body 1 form a double valve seat, and the upper valve spool shaft 5 and the lower valve spool shaft 16 are connected as a whole to form a double valve spool shaft, realizing the synchronous movement of the double valve spool shaft and achieving the function of simultaneously opening and closing the double valves. Under the action of no liquid pressure, the return spring can ensure that the double valves are always in the closed state and open under the action of the external force of drilling fluid during work.

[0061] Optionally, an upper lower valve seat seal 9 and a lower lower valve seat seal 12 are provided between the upper body 1 and the lower valve seat 8. A lower valve seat dynamic seal 13 is provided between the lower valve seat 8 and the lower valve spool shaft 16. An upper and lower valve connection seal 15 is provided between the upper valve spool shaft 5 and the lower valve spool shaft 16

[0062] Optionally, the double valve spool shaft is an assembled integral structure, and there is a certain amount of axial movement allowance, making the double valves both synchronous and independent of each other. While ensuring the synchronous movement of the double valve spool shaft, it can avoid the mutual influence of the double valves closing simultaneously. That is to say, the double valves of the present invention can not only achieve synchronous opening and closing, but also open and close independently of each other. Even if one of them fails, the other can still be normally opened and closed.

[0063] In summary, the downhole integrated double-sealing one-way valve for concentric dual-tube reverse circulation drilling provided by the embodiments of the present invention can simultaneously realize the opening and closing of the central water eye and the dual-tube annulus in downhole dual-tube drilling. Its preferred structure includes: upper body 1, retaining ring 2, upper inner tube 3, inner tube seal 4, upper valve core shaft 5, upper valve upper seal 6, upper valve lower seal 7, lower valve seat 8, lower valve seat upper seal 9, positioning screw pin 10, positioning pin circlip 11, lower valve seat lower seal 12, lower valve seat dynamic seal 13, connecting screw sleeve 14, upper and lower valve connection seal 15, lower valve core shaft 16, return spring 17, lower body 18 and other components. Through these components, flow structures such as upper inner channel 19, upper outer channel 20, outer channel diversion hole 21, inner channel outer diversion hole 22, outer channel cavity 23, lower valve core shaft through hole 24, lower valve annulus 25, and annulus diversion hole 26 on the lower valve core shaft are formed. Among them: The upper end inside of the upper body 1 is designed with a drill pipe thread to connect with the outer pipe of the upper concentric dual-tube drill pipe, and the lower end is designed with a drill pipe thread to connect with the upper end of the lower body 18. The lower end of the lower body 18 is then connected to the lower drill pipe through a drill pipe thread to form the outer body of the present invention. The middle and upper part inside the upper body 1 is also designed with an outer channel diversion hole and an inner channel outer diversion hole. The middle and lower part of the upper body 1 is designed with an outer channel cavity for installing the lower valve seat 8. An upper inner tube 3 is also designed inside the upper body 1, which is designed with an upper inner socket to connect with the inner tube of the upper concentric dual-tube drill pipe to form an inner tube circulation channel. The lower valve seat 8 is inserted into the inside from the lower part of the upper body 1 and fixed by a positioning screw pin. After the lower valve core shaft and the upper valve core shaft are strung together, they are limited by a connecting screw sleeve to form the double valve core shaft of the present invention. Under the action of the concentric dual-tube empty drilling fluid pressure and the return spring, the double valve core shaft can reciprocate up and down inside the upper body 1. The lower end of the lower valve core shaft 16 is also designed with a return spring seat for installing the return spring 17 and inserted into the inside of the upper end of the lower body. For this double-sealing one-way valve, sealing components are designed between the upper body 1, upper inner tube 3, upper valve core shaft 5, lower valve seat 8, lower valve core shaft 16, etc. to ensure the sealing between each channel. Through the design of the double valve seat and the integrated valve core shaft, the opening or closing control of the downhole dual channels can be realized by changing the ground pump on and off, realizing the automatic synchronous opening and closing of the downhole dual channels, improving the reliability of the operation, and improving the on-site operation efficiency and safety.

[0064] The upper body of the present invention is designed with a central water eye (i.e., central flow channel), annulus flow channel, and inner and outer bypass flow channels. The central water eye can be internally and externally connected or closed through the upper valve structure, which can ensure that the drilling fluid passing through the annulus flow channel of the concentric dual-tube enters the central water eye from the inner and outer bypass flow channels after passing through the bottom drilling assembly, realizing the concentric dual-tube reverse circulation drilling operation. Of course, the double-sealing one-way valve of the present invention is also applicable to the downhole operation mode where the drilling fluid flows out through the central water eye and out of the concentric dual-tube annulus.

[0065] Based on the same inventive concept, an embodiment of the present invention further provides a method for realizing concentric dual-tube reverse circulation drilling, and the operation process is as follows Figure 6 shown, including:

[0066] S101: Connect the outer tube of the concentric dual-tube through the upper body, and connect the inner tube of the concentric dual-tube through the upper inner tube;

[0067] S102: After the liquid in the inner tube enters the upper central flow channel and the liquid in the outer tube enters the annulus flow channel, under the action of the liquid pressure in the upper central flow channel and the annulus flow channel, the upper spool shaft and the lower spool shaft move downward, and the upper central flow channel is communicated with the external environment through the inner channel external diversion holes on the body, and the annulus flow channel is communicated with the lower central flow channel through the lower annulus and the annulus diversion holes on the lower spool shaft; thus opening the inner and outer channels of the concentric dual-tube together;

[0068] S103: After the action of the liquid pressure disappears, the upper spool shaft and the lower spool shaft move upward under the action of the return spring, so as to close the inner channel and the outer channel together.

[0069] An embodiment of the present invention further provides an application of a double-sealing one-way valve for concentric dual-tube reverse circulation drilling in concentric dual-tube reverse circulation drilling.

[0070] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy recited.

[0071] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are expressly stated in each claim. On the contrary, as reflected in the appended claims, the present invention resides in less than all of the features of a single disclosed embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, where each claim stands on its own as a separate preferred embodiment of the present invention.

[0072] The foregoing description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but those of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Accordingly, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" as used in the specification or claims, this term is inclusive in a manner similar to the term "including", as that term is interpreted when used as a transitional word in a claim. Further, any use of the term "or" in the specification or claims is to be meant "non-exclusive or".

Claims

1. A double-sealing one-way valve for concentric dual-tube reverse circulation drilling, characterized in that, Comprising: A body, an upper inner tube, an upper valve core shaft and a lower valve core shaft that are sequentially connected inside the body; a lower valve seat is provided between the lower valve core shaft and the body, and a return spring is provided below the lower valve core shaft; The upper inner tube is provided with an upper central flow channel, the lower valve core shaft is provided with a lower central flow channel, and an annular flow channel is provided between the upper inner tube, the upper valve core shaft and the body; a lower annulus is provided between the lower valve core shaft and the body; Under the action of the liquid pressure in the upper central flow channel and the annular flow channel, the upper valve core shaft and the lower valve core shaft move downward, the upper central flow channel is communicated with the external environment through the inner channel external diversion holes on the body, and the annular flow channel is communicated with the lower central flow channel through the lower annulus and the annular diversion holes on the lower valve core shaft; After the liquid pressure action disappears, the upper valve core shaft and the lower valve core shaft move upward under the action of the return spring to close the inner channel and the outer channel.

2. The one-way valve according to claim 1, characterized in that, The body includes an upper body and a lower body; The upper inner tube and the upper valve core shaft are installed in the through holes of the upper body. The upper end of the lower valve core shaft is installed in the upper body through the lower valve seat, and the lower end of the lower valve core shaft is installed in the through hole of the lower body and a return spring is provided in the through hole.

3. The one-way valve according to claim 2, characterized in that, The upper end of the upper body is provided with drill tool threads to connect the outer tube of the concentric double-tube drill tool, and the lower end is provided with drill tool threads to connect the lower body; the lower end of the lower body is provided with drill tool threads to connect the lower drill tool.

4. The one-way valve according to claim 1, characterized in that, A retaining ring is provided in the annular hole between the upper inner tube and the upper body, and the retaining ring is provided with a through-flow hole for communicating the annular flow channel.

5. The one-way valve according to claim 1, characterized in that, The body is provided with an outer channel diversion hole and an outer channel cavity. The annulus between the body and the upper inner tube, the outer channel diversion hole, the outer channel cavity, and the annulus between the body and the upper valve core shaft are communicated to form an annular flow channel; The outer channel diversion holes and the inner channel external diversion holes are circumferentially arranged uniformly, and the outer channel diversion holes and the inner channel external diversion holes are arranged in a cross pattern.

6. The one-way valve according to claim 1, characterized in that, The lower valve core shaft is provided with an upper connection hole to connect the lower end of the upper valve core shaft; The lower end of the lower valve core shaft has a through hole as the lower central flow channel, and a plurality of annular diversion holes are circumferentially arranged uniformly on the side wall of the lower central flow channel.

7. The one-way valve according to claim 1, characterized in that, The upper end of the lower valve core shaft is provided with a first conical surface, and a second conical surface is provided in the through hole of the lower valve seat. The first conical surface and the second conical surface are matched to achieve sealing.

8. The one-way valve according to any one of claims 1-7, characterized in that, The lower valve core shaft is coaxially arranged with the upper valve core shaft, and a connecting sleeve is provided between the lower valve core shaft and the upper valve core shaft.

9. Application of a double-sealing one-way valve for concentric double-tube reverse circulation drilling as described in any one of claims 1-7 in concentric double-tube reverse circulation drilling.

10. A concentric double-tube reverse circulation drilling method, characterized in that, Implemented using a double-sealing one-way valve for concentric double-tube reverse circulation drilling as described in any one of claims 1-7. The method includes: Connecting the outer tube of the concentric double-tube through the upper body, and connecting the inner tube of the concentric double-tube to the upper inner tube; After the liquid in the inner tube enters the upper central flow channel and the liquid in the outer tube enters the annular flow channel, under the action of the liquid pressure in the upper central flow channel and the annular flow channel, the upper valve core shaft and the lower valve core shaft move downward. The upper central flow channel is communicated with the external environment through the inner channel external diversion holes on the body, and the annular flow channel is communicated with the lower central flow channel through the lower annulus and the annular diversion holes on the lower valve core shaft; thus opening the inner and outer channels of the concentric double-tube together; After the liquid pressure action stops, the upper valve core shaft and the lower valve core shaft move upward under the action of the return spring, closing the inner channel and the outer channel together.

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