A floating collar and floating shoe for cementing

Abstract

The present invention relates to the technical field of oil and gas cementing tools, and in particular to a floating collar and floating shoe for cementing, which aims to solve the problem of insufficient reverse pressure bearing of existing floating collar and floating shoe. The floating collar and floating shoe for cementing provided by the present invention comprises a one-way valve, which comprises a valve body and a valve core; the valve core comprises a rod body, a rubber sleeve and a spring sheet; the rubber sleeve is sleeved on one end of the rod body and abuts against the valve body to form a seal; the spring sheet is connected to the rod body and is used to apply a thrust to the rubber sleeve to press the rubber sleeve against the valve body. The one-way valve provided by the present invention improves the sealing and pressure bearing capacity by providing a spring sheet for sealing compensation. When the valve core abuts against the valve body to form a seal under the action of the original spring, the rubber sleeve will squeeze the spring sheet due to the compression deformation, thereby deforming the spring sheet and generating elastic force to further press the rubber sleeve and the valve body, increasing the pressing force and limiting the radial contraction of the rubber sleeve, thereby improving its reverse pressure bearing capacity.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas cementing tools, in particular to a floating collar and floating shoe for cementing. Background Art

[0002] Floating collars and floating shoes are one of the important tools to ensure cementing construction, and their reverse pressure-bearing reliability is the key to ensure that cement slurry does not flow back. However, as exploration and development continue to move towards ultra-deep and ultra-deep wells, drilling depths continue to break records, and the reverse pressure-bearing requirements of floating collars and floating shoes are getting higher and higher. In the accompanying high temperature, acid, alkali, salt corrosion and large-displacement high-pressure erosion construction environment, conventional cementing floating collars and floating shoes are increasingly failing, resulting in plugging inside the pipe, cement slurry outside the pipe not returning to its place, and other complex projects. Summary of the invention

[0003] The object of the present invention is to provide a floating collar and a floating shoe for cementing, so as to solve the problem that the existing floating collar and a floating shoe have insufficient reverse pressure bearing.

[0004] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0005] A floating shoe for cementing, the floating shoe comprising a one-way valve, the one-way valve comprising a valve body and a valve core, the valve core being inserted into the valve body;

[0006] The valve core includes a rod body, a rubber sleeve and a spring sheet; the rubber sleeve is sleeved on one end of the rod body and abuts against the valve body to form a seal; the spring sheet is connected to the rod body and is used to apply thrust to the rubber sleeve to press the rubber sleeve against the valve body.

[0007] Furthermore, the one-way valve also includes a return spring, which is sleeved on the rod body and is used to apply a thrust to the valve core so that the rubber sleeve abuts against the valve body.

[0008] Further, the valve body includes an upper valve seat and a lower valve seat;

[0009] The valve core is inserted into the upper valve seat and the lower valve seat, and the rubber sleeve abuts against the upper valve seat; one end of the return spring abuts against the valve core, and the other end abuts against the lower valve seat.

[0010] Furthermore, along the direction from the upper valve seat to the lower valve seat, the diameter and wall thickness of the rubber sleeve gradually increase, and the spring sheet is arranged in the rubber sleeve and is located at one end of the rubber sleeve close to the lower valve seat.

[0011] Furthermore, the float shoe also includes a float shoe body, and the upper valve seat and the lower valve seat are installed on the float shoe body.

[0012] Furthermore, the upper valve seat is made of aluminum alloy, the inner hole surface is provided with an insulating coating, and the surface of the insulating coating is provided with an anti-corrosion coating;

[0013] The insulating coating is obtained by using a magnetron sputtering process, and the material is silicon or ceramic; the anti-corrosion coating is obtained by using a magnetron sputtering process, and the material is nickel, monel alloy or titanium alloy.

[0014] Furthermore, the valve body also includes a wear-resistant ring; the rod body is inserted into the wear-resistant ring and is slidably connected with the wear-resistant ring, and the wear-resistant ring is inserted into the lower valve seat; the material of the wear-resistant ring is hard alloy;

[0015] The lower valve seat is provided with a plurality of circulation holes evenly distributed around its axis, and the inner surfaces of the circulation holes are sprayed with tungsten carbide coatings; the portion of the rod body not wrapped by the rubber sleeve is provided with a graphite coating.

[0016] Furthermore, the float shoe further comprises a guide shoe, the guide shoe being rotatably connected to the float shoe body and being coaxially arranged with the float shoe body;

[0017] The guide shoe is provided with a plurality of eccentric holes evenly distributed around its own axis, the axis of the eccentric hole is perpendicular to the axis of the guide shoe but does not intersect with the axis of the guide shoe, and the eccentric hole is connected with the circulation hole.

[0018] Furthermore, the surface of the guide shoe is provided with a plurality of spiral bosses evenly distributed around its axis, and the surface of the spiral bosses is welded with hard alloy;

[0019] One end of the guide shoe away from the float shoe body is set as an ellipsoidal surface, and the ellipsoidal surface is partially cut to form an eccentric structure. The eccentric structure rotates around the axis of the guide shoe to generate polarization to eliminate bubbles in the cement slurry.

[0020] Furthermore, the float shoe further comprises a ball bearing, the guide shoe is inserted into the float shoe body and forms an annular cavity with the float shoe body, and the ball bearing is installed in the annular cavity;

[0021] The guide shoe and the float shoe body are in clearance fit, and the ball is simultaneously clamped in the annular grooves of the guide shoe and the float shoe body and in rolling contact with the annular groove;

[0022] The guide shoe and the annular groove of the float shoe body form the annular cavity.

[0023] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0024] The present invention provides a floating shoe for cementing, wherein the floating shoe comprises a one-way valve, the one-way valve comprises a valve body and a valve core, and the valve core is inserted into the valve body; the valve core comprises a rod body, a rubber sleeve and a spring sheet; the rubber sleeve is sleeved on one end of the rod body and abuts against the valve body to form a seal; the spring sheet is connected to the rod body and is used to apply thrust to the rubber sleeve to press the rubber sleeve against the valve body.

[0025] The one-way valve provided by the present invention improves the sealing performance and pressure bearing capacity by providing a spring sheet for sealing compensation. When the valve core abuts against the valve body to form a seal under the action of the original spring, the rubber sleeve will be compressed and deformed to squeeze the spring sheet, thereby causing the spring sheet to deform and generate elastic force to further press the rubber sleeve and the valve body, thereby increasing the pressing force and controlling the deformation direction of the rubber sleeve, limiting the axial elongation of the rubber sleeve, thereby avoiding the situation where the rubber sleeve has a gap with the valve body due to axial elongation and radial contraction, ensuring the sealing performance and improving the reverse pressure bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of the structure of a float shoe for cementing provided in an embodiment of the present invention;

[0028] Figure 2 for Figure 1 A partial enlarged view of the middle A;

[0029] Figure 3 It is a structural schematic diagram of the valve core and the valve body;

[0030] Figure 4 This is the main view of the guide shoe;

[0031] Figure 5 This is a bottom view of the guide shoe;

[0032] Figure 6 This is a top view of the guide shoe;

[0033] Figure 7 A schematic structural diagram of a floating collar for cementing provided in an embodiment of the present invention.

[0034] Icons: 100-check valve; 200-floating shoe body; 300-guide shoe; 400-floating hoop body; 500-ball; 600-plug; 700-screw; 110-valve body; 120-valve core; 130-reset spring; 111-upper valve seat; 112-lower valve seat; 113-wear-resistant ring; 121-rod body; 122-rubber sleeve; 123-spring sheet; 310-eccentric hole; 320-spiral boss; 330-milling surface; 101-circulation hole. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0038] Floating collars and floating shoes are one of the important tools to ensure cementing construction, and their reverse pressure-bearing reliability is the key to ensuring that cement slurry does not flow back. However, as exploration and development continue to move towards ultra-deep and ultra-deep wells, drilling depths continue to break records, and the reverse pressure requirements for floating collars and floating shoes are getting higher and higher, and there is a problem of insufficient reverse pressure.

[0039] In view of this, the present invention provides a floating shoe for cementing, the floating shoe comprising a one-way valve 100, the one-way valve 100 comprising a valve body 110 and a valve core 120, the valve core 120 being inserted into the valve body 110; the valve core 120 comprising a rod body 121, a rubber sleeve 122 and a spring sheet 123; the rubber sleeve 122 is sleeved on one end of the rod body 121 and abuts against the valve body 110 to form a seal; the spring sheet 123 is connected to the rod body 121, and is used to apply thrust to the rubber sleeve 122 to press the rubber sleeve 122 against the valve body 110.

[0040] The one-way valve 100 provided by the present invention improves the sealing performance and pressure bearing capacity by providing a spring sheet 123 for sealing compensation. When the valve core 120 abuts against the valve body 110 to form a seal under the action of the original spring, the rubber sleeve 122 is compressed and deformed to squeeze the spring sheet 123, thereby causing the spring sheet 123 to deform and generate elastic force to further press the rubber sleeve 122 and the valve body 110, thereby increasing the pressing force and controlling the deformation direction of the rubber sleeve 122, limiting the axial elongation of the rubber sleeve 122, thereby avoiding the situation where the rubber sleeve 122 has a gap with the valve body 110 due to axial elongation and radial contraction, ensuring the sealing performance and improving the reverse pressure bearing capacity.

[0041] The following combination Figure 1-Figure 7 The structure and shape of the floating collar and floating shoe for cementing provided in this embodiment are described in detail:

[0042] In this embodiment, the float shoe includes a one-way valve 100, a float shoe body 200 and a guide shoe 300. The one-way valve 100 is inserted into the float shoe body 200, and the guide shoe 300 is rotatably connected to the lower end of the float shoe body 200. The one-way valve 100 includes a valve body 110, a valve core 120 and a return spring 130. The valve core 120 is inserted into the valve body 110 and is slidably connected to the valve body 110. One end of the valve core 120 abuts against the valve body 110 to form a seal. The return spring 130 is sleeved on the valve core 120, one end of which abuts against the valve body 110, and the other end abuts against the valve core 120, and is used to apply thrust to the valve core 120 to make the valve core 120 abut against the valve body 110, such as Figure 1 , Figure 2 shown.

[0043] Specifically, the valve body 110 includes an upper valve seat 111, a lower valve seat 112 and a wear ring 113. Figure 1 As shown. The upper valve seat 111 and the lower valve seat 112 are both installed on the float shoe body 200 in a threaded connection manner, and the wear-resistant ring 113 is inserted into the lower valve seat 112 and connected in an adhesive manner. The valve core 120 includes a rod body 121, a rubber sleeve 122 and a spring sheet 123. The rod body 121 is inserted into the wear-resistant ring 113 and is slidably connected to the wear-resistant ring 113. The rubber sleeve 122 is sleeved on the end of the rod body 121 away from the wear-resistant ring 113 and is used to abut against the upper valve seat 111 to form a seal; a plurality of spring sheets 123 are evenly distributed in an annular shape around the axis of the rod body 121 and are connected to the rod body 121. At the same time, the spring sheet 123 is arranged in the rubber sleeve 122 to resist the deformation of the rubber sleeve 122 when the rubber sleeve 122 and the upper valve seat 111 are squeezed against each other, thereby improving the strength and elasticity of the rubber sleeve 122, thereby improving the sealing performance to improve the reverse pressure bearing capacity.

[0044] In this embodiment, the spring sheet 123 is disposed between the upper valve seat 111 and the lower valve seat 112, and is used to apply a thrust in the direction of the upper valve seat 111. Compared with disposing the spring sheet 123 at the lower end of the rubber sleeve 122, disposing the spring sheet 123 in the rubber sleeve 122 can improve the tightness of the combination of the spring sheet 123 and the rubber sleeve 122, thereby limiting the downward deformation of the spring sheet 123 to increase the upward thrust of the spring sheet 123. Furthermore, the spring sheet 123 has a Z-shaped structure to obtain better elastic force.

[0045] In this embodiment, the rubber sleeve 122 wraps one end of the rod body 121 and the spring sheet 123 in a vulcanized manner. Figure 1 , Figure 2 As shown, the head of the rubber sleeve 122 is spherical, and along the direction from the upper valve seat 111 to the lower valve seat 112, the diameter and wall thickness of the rubber sleeve 122 gradually increase and form a tapered skirt structure, and the spring sheet 123 is arranged at one end of the rubber sleeve 122 close to the lower valve seat 112. That is, the contact surface between the upper valve seat 111 and the rubber sleeve 122 is an inclined surface, and the hole of the upper valve seat 111 for inserting the rubber sleeve 122 is a tapered through hole. Under the reverse high pressure state, the rubber body with a tapered skirt structure gradually becoming thicker can provide a better sealing effect and a stronger ability to resist deformation.

[0046] When the return spring 130 applies thrust to the valve core 120 to squeeze the rubber sleeve 122 on the upper valve seat 111. When subjected to reverse pressure in the same direction as the thrust of the return spring 130, the rubber sleeve 122 will expand radially and shrink axially. When the pressure exceeds the limit of the rubber sleeve 122, the diameter of the rubber sleeve 122 will shrink and extend axially, thereby generating a gap between the rubber sleeve 122 and the upper valve seat 111, causing sealing failure. The spring sheet 123 limits the downward extension of the rubber sleeve 122, and the contact surface of the inclined surface limits the upward extension of the rubber sleeve 122, thereby reducing the deformation space of the rubber sleeve 122 after being squeezed, limiting its extension along the axial direction, avoiding radial contraction after excessive pressure, resulting in gaps, and causing sealing failure, thereby achieving the purpose of improving reverse pressure bearing capacity and sealing performance. In addition, the elasticity of the spring sheet 123 avoids damage to the rubber sleeve 122 due to hard limit, and avoids excessive force on the rubber sleeve 122 during the extrusion and friction process with the upper valve seat 111, resulting in damage and reduced service life.

[0047] In this embodiment, the return spring 130 abuts against the rubber sleeve 122, thereby further limiting the downward extension of the rubber sleeve 122 and the downward deformation of the spring sheet 123, thereby improving the reverse pressure bearing capacity.

[0048] In this embodiment, the upper valve seat 111 is made of aluminum alloy, an insulating coating is provided on the surface of the inner hole, and an anti-corrosion coating is provided on the surface of the insulating coating. Specifically, the insulating coating is obtained by magnetron sputtering process, and the material is silicon or ceramic; the anti-corrosion coating is obtained by magnetron sputtering process, and the material is nickel, monel alloy or titanium alloy. The insulating coating can prevent the aluminum alloy from electrochemically deteriorating, and the anti-corrosion coating prevents the sealing surface of the valve body 110 from being corroded in a liquid environment containing chloride ions that are easy to corrode the aluminum alloy, thereby ensuring the sealing performance. The material of the wear-resistant ring 113 is cemented carbide, and the part of the rod body 121 not wrapped by the rubber sleeve 122 is provided with a graphite coating to improve wear resistance and lubrication, so as to avoid the high-frequency reciprocating motion between the rod body 121 and the lower valve seat 112 from causing the rod body 121 to break due to friction and wear, resulting in the failure of the floating hoop and floating shoe.

[0049] In this embodiment, the lower valve seat 112 is provided with a plurality of circulation holes 101 evenly distributed around its own axis, and the inner surface of the circulation hole 101 is sprayed with a tungsten carbide coating to improve its erosion resistance, so that it can maintain its structural strength under large-displacement circulation erosion, and no fracture caused by erosion will occur between the holes, causing the valve plate to fall off.

[0050] In this embodiment, the guide shoe 300 is rotatably connected to the float shoe body 200 and is coaxially arranged with the float shoe body 200. The guide shoe 300 is provided with a plurality of eccentric holes 310 evenly distributed around its own axis, and the axis of the eccentric hole 310 is perpendicular to the axis of the guide shoe 300 but does not intersect with the axis of the guide shoe 300. The surface of the guide shoe 300 is provided with a plurality of spiral bosses 320 evenly distributed around its own axis; the end of the guide shoe 300 away from the float shoe body 200 is provided with an ellipsoidal surface, and a portion of the ellipsoidal surface is cut to form an eccentric structure.

[0051] Specifically, Figure 4 , Figure 5 , Figure 6 As shown, the upper end of the guide shoe 300 is inserted into the float shoe body 200 and rotatably connected with the float shoe body 200, and the lower end is set as an ellipsoidal structure. The surface of the ellipsoidal structure is milled to obtain a milling surface 330, thereby forming an eccentric ellipsoidal structure.

[0052] In this embodiment, the upper surface of the spiral boss 320 is an inclined surface, and the lower surface is an arc surface, and a hard alloy layer is built-up on the surface to improve wear resistance.

[0053] In this embodiment, the float shoe further includes a ball 500, a plug 600 and a screw 700. Figure 2As shown. The float shoe body 200 and the guide shoe 300 form an annular cavity, and a plurality of balls 500 are installed in the annular cavity, so that the sliding friction between the float shoe body 200 and the guide shoe 300 is converted into rolling friction, thereby reducing the friction. In this embodiment, an annular groove is provided on the inner surface of the float shoe body 200 and the outer surface of the guide shoe 300, and the two annular grooves are aligned to form an annular cavity. At the same time, the float shoe body 200 and the guide shoe 300 are clearance-fitted to avoid mutual friction, and rolling friction is achieved only through the contact of the balls 500.

[0054] A through hole connected to the annular cavity is provided on the float shoe body 200 for loading the ball 500 into the annular cavity. After loading the ball 500, the plug 600 is inserted into the through hole to prevent the ball 500 from coming out. The plug 600 can be fixed on the float shoe body 200 by threaded connection or welding.

[0055] In addition, a limiting annular groove is provided on the guide shoe 300, and a screw 700 is installed on the float shoe body 200 and inserted into the limiting annular groove. The screw 700 is slidably connected with the limiting annular groove to ensure that the guide shoe 300 is rotatably connected with the float shoe body 200 while avoiding axial relative displacement and preventing the guide shoe 300 from falling off. That is, a threaded hole is provided on the side wall of the float shoe body 200 for connection with the screw 700, and the screw 700 passes through the side wall of the float shoe body 200 and is inserted into the limiting annular groove. Specifically, a plurality of screws 700 are evenly distributed in an annular shape around the axis of the float shoe body 200, and the screw 700 includes two sections, a threaded section and a cylindrical section. The cylindrical section is inserted into the limiting annular groove and slidably connected with the limiting annular groove, and the threaded section is threadedly connected with the float shoe body 200.

[0056] In this embodiment, the guide shoe 300 can rotate around the axis at any angle under the action of external force. When the pipe string is lowered and encounters obstacles, the guide shoe 300 can rotate around its own axis under the action of external force to guide the pipe string through. When the circulation is established, the reverse thrust generated by the cement slurry ejected from the eccentric hole 310 can drive the guide shoe 300 to rotate and generate polarization force, thereby removing obstacles around the guide shoe 300. At this time, the hard alloy on the surface of the spiral boss 320 removes the obstacles by scraping. The polarization effect can eliminate bubbles in the cement slurry, and the spiral boss 320 can also generate local vortex to improve the flow state of the cement slurry and improve the cementing quality.

[0057] Specifically, when cement slurry is injected, the return spring 130 is compressed, the rubber sleeve 122 is out of contact with the upper valve seat 111 , and the cement slurry flows through the inner hole of the upper valve seat 111 and the circulation hole 101 in sequence into the guide shoe 300 , and finally ejected from the eccentric hole 310 .

[0058] In this embodiment, the float collar includes a float collar body 400 and a one-way valve 100, and the one-way valve 100 is installed on the float collar body 400. The one-way valve 100 of the float collar and the float shoe has the same structure. Figure 7 shown.

[0059] In this embodiment, the reverse pressure bearing capacity means that under the axial downward force, the reset spring 130 can be axially compressed to connect the circulation channel, and the external force disappears or the reset spring 130 is reset under the axial upward force, and the rubber sleeve 122 is abutted against the upper valve seat 111 to close the circulation channel. At this time, the rubber sleeve 122 is squeezed and deformed to force the spring sheet 123 to generate an elastic reaction force, so that the rubber sleeve 122 fits tightly with the upper valve seat 111 to achieve sealing compensation. Under the reverse high pressure state, the gradually thickening rubber body of the conical skirt structure can provide a better sealing effect and have a stronger ability to resist deformation, and the elastic reaction force generated by the spring sheet 123 is greater, which has a better sealing compensation effect.

[0060] The floating hoop and floating shoe for cementing provided in this embodiment have improved the corrosion resistance, erosion resistance and reverse pressure bearing capacity by upgrading the structure, material and function of the internal valve parts, and have improved the cement slurry displacement efficiency by modifying the guide shoe 300, thereby improving the cementing construction efficiency of ultra-deep and ultra-deep wells and the cementing quality. Specifically, the corrosion resistance and erosion resistance of the tool are improved by spraying anti-corrosion materials, lubricating wear-resistant materials and anti-erosion materials on the surface; the one-way valve 100 adopts compensating elastic seals and special-shaped rubber bodies to improve the reverse pressure bearing performance; the guide shoe 300 has multiple functions such as guiding the pipe string, removing rock debris, swirl, polarization, etc., which improves the safety of pipe string entry and cementing quality.

[0061] 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 it. 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A floating collar and a floating shoe for cementing, characterized in that: The float shoe comprises a one-way valve (100), the one-way valve (100) comprises a valve body (110), a valve core (120) and a return spring (130), the valve core (120) being inserted into the valve body (110); The valve core (120) comprises a rod body (121), a rubber sleeve (122) and a spring sheet (123); the rubber sleeve (122) is sleeved on one end of the rod body (121) and abuts against the valve body (110) to form a seal; the spring sheet (123) is connected to the rod body (121) and is used to apply a thrust to the rubber sleeve (122) so as to press the rubber sleeve (122) against the valve body (110); The return spring (130) is sleeved on the rod body (121) and is used to apply a thrust to the valve core (120) so that the rubber sleeve (122) abuts against the valve body (110); The valve body (110) comprises an upper valve seat (111) and a lower valve seat (112); along the direction from the upper valve seat (111) to the lower valve seat (112), the diameter and wall thickness of the rubber sleeve (122) gradually increase; The spring sheet (123) is arranged in the rubber sleeve (122) and is located at one end of the rubber sleeve (122) close to the lower valve seat (112); The float shoe further comprises a float shoe body (200), and the float shoe further comprises a guide shoe (300), wherein the guide shoe (300) is rotatably connected to the float shoe body (200) and is coaxially arranged with the float shoe body (200); The surface of the guide shoe (300) is provided with a plurality of spiral bosses (320) evenly distributed around its axis; one end of the guide shoe (300) away from the float shoe body (200) is provided as an ellipsoidal surface; a portion of the ellipsoidal surface is cut to form an eccentric structure; the eccentric structure rotates around the axis of the guide shoe (300) to generate polarization to eliminate bubbles in cement slurry.

2. The floating collar and floating shoe for cementing according to claim 1, characterized in that: The valve core (120) is inserted into the upper valve seat (111) and the lower valve seat (112), and the rubber sleeve (122) abuts against the upper valve seat (111); one end of the return spring (130) abuts against the valve core (120), and the other end abuts against the lower valve seat (112).

3. The floating collar and floating shoe for cementing according to claim 2, characterized in that: The upper valve seat (111) and the lower valve seat (112) are mounted on the float shoe body (200).

4. The floating collar and floating shoe for cementing according to claim 2, characterized in that: The upper valve seat (111) is made of aluminum alloy, an inner hole surface is provided with an insulating coating, and an anti-corrosion coating is provided on the surface of the insulating coating; The insulating coating is obtained by using a magnetron sputtering process, and the material is silicon or ceramic; the anti-corrosion coating is obtained by using a magnetron sputtering process, and the material is nickel, monel alloy or titanium alloy.

5. The floating collar and floating shoe for cementing according to claim 3, characterized in that: The valve body (110) further comprises a wear-resistant ring (113); the rod body (121) is inserted into the wear-resistant ring (113) and is slidably connected to the wear-resistant ring (113); the wear-resistant ring (113) is inserted into the lower valve seat (112); the material of the wear-resistant ring (113) is hard alloy; The lower valve seat (112) is provided with a plurality of circulation holes (101) evenly distributed around its axis, and the inner surfaces of the circulation holes (101) are sprayed with a tungsten carbide coating; the portion of the rod body (121) not wrapped by the rubber sleeve (122) is provided with a graphite coating.

6. The floating collar and floating shoe for cementing according to claim 5, characterized in that The guide shoe (300) is provided with a plurality of eccentric holes (310) evenly distributed around its axis, the axis of the eccentric hole (310) being perpendicular to the axis of the guide shoe (300) but not intersecting with the axis of the guide shoe (300), and the eccentric hole (310) being in communication with the circulation hole (101).

7. The floating collar and floating shoe for cementing according to claim 6, characterized in that: The surface of the spiral boss (320) is built-up with hard alloy.

8. The floating collar and floating shoe for cementing according to claim 6, characterized in that: The float shoe further comprises a ball bearing (500), the guide shoe (300) is inserted into the float shoe body (200) and forms an annular cavity with the float shoe body (200), and the ball bearing (500) is installed in the annular cavity; The guide shoe (300) and the float shoe body (200) are clearance-matched, and the ball (500) is simultaneously clamped in the annular grooves of the guide shoe (300) and the float shoe body (200) and is in rolling contact with the annular groove; The guide shoe (300) and the annular groove of the float shoe body (200) form the annular cavity.

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