Intelligent waterproof slurry air-replacing pup joint for well cementation and method for prompting completion of slurry replacement

Abstract

The invention discloses an intelligent waterproof slurry air replacement nipple for well cementation and a method for prompting completion of slurry replacement. The short section comprises a short section body, a valve bottom plate, a valve plate, a valve cover plate, a motor, a controller and a motor fixing seat. Wherein valve holes are formed in the valve bottom plate, the valve plate and the valve cover plate, and the valve plate is meshed with the output end of the motor; the controller comprises two voltage detection pieces, a battery, a single-chip microcomputer and a diversion trench, the single-chip microcomputer is used for obtaining voltage signals detected by the two voltage detection pieces and detecting whether the flowing shaft liquid changes or not when the shaft liquid flows through the collection diversion trench, and when it is determined that slurry replacement is completed according to the change of the shaft liquid, the motor is controlled to drive the valve plate to rotate, so that slurry replacement is completed. The valve holes in the valve plate and the valve holes in the valve bottom plate and the valve cover plate are in a circulating intermittent communication or non-communication state, so that a circulating channel in the sleeve is opened and closed, ground pumping pressure fluctuates, displacement fluid is prompted to reach a preset position, cement paste is prevented from being empty, and the well cementation quality is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical fields of geothermal energy and oil and gas drilling, and particularly relates to an intelligent anti-cement slurry displacement short joint for cementing and a method for prompting the completion of slurry displacement. Background Art

[0002] Cementing refers to the construction process of lowering a casing into a wellbore and injecting cement slurry to consolidate the casing with the well wall. The purpose of cementing is to isolate oil, gas, and water layers, prevent the wellbore from collapsing, and ensure the normal production of oil wells.

[0003] With the continuous deepening of oilfield exploration and development, there are more and more deep wells and complex wells, the downhole working conditions are getting worse and worse, and it is becoming more and more difficult to ensure the cementing quality. If the position of the cementing plug in the wellbore is not pressure bumped during the cementing process, it cannot be judged, which greatly increases the risk of cement slurry displacement. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide an intelligent anti-cement slurry displacement short joint for cementing and a method for prompting the completion of slurry displacement that overcome or at least partially solve the above problems.

[0005] In a first aspect, an embodiment of the present invention provides an intelligent anti-cement slurry displacement short joint for cementing, including:

[0006] A short joint body, a valve bottom plate, a valve plate, a valve cover plate, a motor, a controller, and a motor fixing seat;

[0007] The motor and the controller are arranged in the motor fixing seat;

[0008] The motor fixing seat is connected to one end of the short joint body;

[0009] The inside of the short joint body is a cavity, and the valve bottom plate, the valve plate, and the valve cover plate are sequentially arranged in the cavity inside the short joint;

[0010] Valve holes are provided on the valve bottom plate, the valve plate, and the valve cover plate, and the valve plate is engaged with the output end of the motor;

[0011] The controller includes two voltage detection plates, a battery, a single-chip microcomputer, and a diversion groove. The single-chip microcomputer is configured to obtain the voltage signals detected by the two voltage detection plates when the wellbore fluid flows through the collection diversion groove, detect whether the flowing wellbore fluid has changed according to the voltage signals detected by the two voltage detection plates, and when it is determined that the displacement slurry has been completed based on the change in the wellbore fluid, control the motor to drive the valve plate to rotate, so that the valve holes on the valve plate are in a state of cyclically intermittently communicating and disconnecting with the valve holes on the valve bottom plate and the valve cover plate, so as to open and close the inner casing circulation channel, cause the ground pump pressure to fluctuate, and indicate that the displacement fluid has reached the predetermined position.

[0012] In one embodiment, the nipple body is cylindrical, and is sequentially provided with a connection thread for connecting the lower drill string, a valve bottom plate key for connecting the valve bottom plate, a motor gear rotation groove, a valve cover plate fixing threaded hole for connecting the valve cover plate, and a motor fixing seat fixing threaded hole for connecting the motor fixing seat from bottom to top.

[0013] In one embodiment, a valve bottom plate fixing groove is circumferentially provided at the lower end of the valve bottom plate, and the valve bottom plate fixing groove is clamped with the valve bottom plate key.

[0014] In one embodiment, the valve bottom plate, the valve plate, and the valve cover plate are all disc-shaped and are each provided with at least two valve holes;

[0015] A first ball groove is provided on the upper surface of the valve bottom plate;

[0016] Second ball grooves are respectively circumferentially provided on the upper surface and the lower surface of the valve plate;

[0017] A third ball groove is provided on the lower surface of the valve cover plate;

[0018] The valve cover plate, the valve plate, and the valve bottom plate are stacked up and down, the positions of the first ball groove, the second ball groove, and the third ball groove correspond, and balls are respectively arranged in the space between the first ball groove and the second ball groove and between the second ball groove and the third ball groove.

[0019] In one embodiment, a plurality of first fixing pin holes are circumferentially provided on the outer side of the valve cover plate;

[0020] The plurality of first fixing pin holes of the valve cover plate are connected to the valve cover plate fixing threaded holes of the nipple body.

[0021] In one embodiment, the motor includes: a motor body and a gear;

[0022] The output shaft of the motor body is connected to the gear; teeth are provided on the outer circumference of the valve plate;

[0023] The gear meshes with the teeth on the outer circumference of the valve plate.

[0024] In one embodiment, the motor fixing base is cylindrical, and a motor installation groove and a controller installation groove are provided at the bottom;

[0025] The controller is located in the controller installation groove of the motor fixing base;

[0026] The top of the motor body of the motor is arranged in the motor installation groove of the motor fixing base, and the gear of the motor is accommodated in the motor gear rotation groove provided at the top of the nipple body.

[0027] In one embodiment, the intelligent anti-cement slurry displacement empty nipple for well cementing further includes:

[0028] The fixing base threaded hole on the nipple body matches the pin hole on the motor fixing base, and the nipple body is connected to the motor fixing base through the fixing base threaded hole and the pin hole on the motor fixing base.

[0029] In one embodiment, the diversion groove of the controller is arranged outside the single-chip microcomputer, and the two voltage detection pieces are arranged inside the diversion groove;

[0030] The diversion groove has an opening and an outlet, and its opening is larger than the outlet;

[0031] The two voltage detection pieces are connected to the positive and negative electrodes of the battery after being connected in series with a resistor;

[0032] The single-chip microcomputer is electrically connected to the two voltage detection pieces.

[0033] In a second aspect, an embodiment of the present invention provides a method for using the intelligent anti-cement slurry displacement empty nipple for well cementing as described above to prompt that the slurry displacement has been completed, including the following steps:

[0034] During the well cementing process, the intelligent anti-cement slurry displacement empty nipple for well cementing obtains the voltage signals detected by its two voltage detection pieces;

[0035] The intelligent anti-cement slurry displacement empty nipple for well cementing detects whether the wellbore fluid flowing through changes according to the voltage signals detected by the two voltage detection pieces;

[0036] When it is determined that the slurry displacement has been completed according to the change of the wellbore fluid, the intelligent anti-cement slurry displacement empty nipple for well cementing controls the motor to drive the valve plate to rotate, so that the valve holes on the valve plate are in a state of being intermittently connected and disconnected with the valve holes on the valve bottom plate and the valve cover plate in a cycle, so as to open and close the circulation channel in the casing, cause the ground pump pressure to fluctuate, and prompt that the displacement fluid has reached the predetermined position.

[0037] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0038] The intelligent anti-cement slurry displacement short joint for cementing provided by the embodiments of the present invention can automatically and intelligently identify that the displacement of the slurry has been completed. When cementing and displacing the slurry and the plug fails to bump and press, it automatically and intermittently closes the inner circulation channel of the casing, causing the ground pump pressure to fluctuate, indicating that the displacement of the slurry has been completed (the displacement fluid reaches the preset position), avoiding the displacement of the cement slurry, and thus ensuring the cementing quality.

[0039] Other features and advantages of the present invention will be described in the following specification, and some of them will become obvious from the specification, or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written specification, claims, and drawings.

[0040] The following will further describe the technical solutions of the present invention in detail through the drawings and embodiments. Description of the Drawings

[0041] 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:

[0042] Figure 1 is the overall structural schematic diagram of the intelligent anti-cement slurry displacement short joint for cementing in the embodiments of the present invention;

[0043] Figure 2 is the structural schematic diagram of the valve bottom plate in the embodiments of the present invention

[0044] Figure 3A and 3B are respectively the structural schematic diagrams of the controller in the embodiments of the present invention;

[0045] Figure 4A and Figure 4B is the structural schematic diagram of the motor fixing seat in the embodiments of the present invention;

[0046] Figure 5 is the structural schematic diagram of the valve bottom plate in the embodiments of the present invention;

[0047] Figure 6 is the structural schematic diagram of the valve plate in the embodiments of the present invention;

[0048] Figure 7 is the structural schematic diagram of the valve cover plate in the embodiments of the present invention;

[0049] Figure 8 is the structural schematic diagram of the motor in the embodiments of the present invention;

[0050] Figure 9This is a schematic diagram of the circuit inside the controller in the embodiment of the present invention.

[0051] Description of the reference numerals:

[0052] 1. Sub-section body; 2. Valve bottom plate; 3. Valve plate; 4. Valve cover plate; 5. Motor; 6. Controller; 7. Motor fixing seat;

[0053] 11. Valve bottom plate key; 12. Motor gear rotation groove; 13. Valve cover plate fixing threaded hole; 14. Motor fixing seat fixing threaded hole;

[0054] 21. Valve hole; 22. Valve bottom plate fixing groove; 23. First ball groove; 31. Tooth; 32. Second ball groove; 33. Ball; 41. Third ball groove; 42. First fixing pin hole; 51. Gear; 52. Motor body; 53. Second fixing pin hole;

[0055] 61. Battery; 62. Single-chip microcomputer; 63. Voltage detection piece; 64. Flow guiding groove; 71. Controller installation groove; 72. Motor installation groove; 73. Pin hole; 74. Thread. Detailed implementation manners

[0056] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail 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.

[0057] Refer to Figure 1 , Figure 2 , Figure 3A and Figure 3B As shown in

[0058] a smart anti-cement slurry displacement short joint for well cementing provided by an embodiment of the present invention includes:

[0059] The motor 5 and the controller 6 are arranged in the motor fixing seat 7;

[0060] The motor fixing seat 7 is connected to one end of the sub-section body 1;

[0061] The inside of the sub-section body 1 is a cavity, and the valve bottom plate 2, the valve plate 3 and the valve cover plate 4 are sequentially arranged in the cavity inside the sub-section body 1;

[0062] Valve holes 21 are provided on the valve bottom plate 2, the valve plate 3 and the valve cover plate 4, and the valve plate 3 meshes with the output end of the motor 5;

[0063] The controller 6 includes two voltage detection pieces 63, a battery 61, a single-chip microcomputer 62, and a diversion groove 64. The single-chip microcomputer 62 is configured to obtain the voltage signals detected by the two voltage detection pieces 63 when the wellbore fluid flows through the collection diversion groove 64, and detect whether the flowing wellbore fluid has changed according to the voltage signals detected by the two voltage detection pieces 63. When it is determined that the displacement slurry has been completed based on the change in the wellbore fluid, the single-chip microcomputer 62 controls the motor 5 to drive the valve plate 3 to rotate, so that the valve holes 21 on the valve plate 3 are in a state of being cyclically intermittently connected and disconnected from the valve holes 21 on the valve bottom plate 2 and the valve cover plate 4, so as to open and close the inner circulation channel of the casing, cause the ground pump pressure to fluctuate, and prompt that the displacement fluid has reached the predetermined position.

[0064] The above intelligent anti-cement slurry displacement empty joint for cementing can automatically and intelligently identify that the displacement slurry has been completed. When cementing and displacing slurry, and the rubber plug fails to touch and press, it automatically closes the inner circulation channel of the casing intermittently in a cycle, and by causing the ground pump pressure to fluctuate, it prompts that the displacement slurry has been completed (the displacement fluid reaches the preset position), avoids the cement slurry from being displaced empty, and ensures the cementing quality.

[0065] In one embodiment, referring to Figure 2 As shown, the short joint body 1 is cylindrical, and is sequentially provided with a connection thread for connecting the lower drill string, a valve bottom plate key 11 for connecting the valve bottom plate 2, a motor gear rotation groove 12, a valve cover plate fixing threaded hole 13 for connecting the valve cover plate 4, and a motor fixing seat 7 fixing threaded hole for connecting the motor fixing seat 7 from bottom to top.

[0066] Referring to Figure 2 and Figure 4A As shown, the fixing seat threaded hole on the short joint body 1 matches the pin hole 73 on the motor fixing seat 7, and the short joint body 1 is connected to the motor fixing seat 7 through the fixing seat threaded hole and the pin hole 73 on the motor fixing seat 7.

[0067] From Figure 2 and Figure 4A It can be seen that the pin hole 73 on the motor fixing seat 7 matches the fixing seat threaded hole 14 on the short joint body 1, and the motor fixing seat 7 and the short joint body 1 are connected by, for example, screws.

[0068] In one embodiment, in the above intelligent anti-cement slurry displacement empty joint for cementing, a valve bottom plate fixing groove is circumferentially arranged at the lower end of the valve bottom plate 2, and the valve bottom plate fixing groove is clamped with the valve bottom plate key 11.

[0069] In one embodiment, referring to Figure 5 , Figure 6 and Figure 7 As shown, the valve bottom plate 2, the valve plate 3, and the valve cover plate 4 are all disc-shaped, and are each provided with at least two valve holes 21;

[0070] As Figures 5 - 7 shown, two symmetrical valve holes 21 are provided on each of the valve bottom plate 2, the valve plate 3 and the valve cover plate 4. As known to those skilled in the art, more than two valve holes 21 can also be provided on the valve bottom plate 2, the valve plate 3 and the valve cover plate 4.

[0071] The sizes of the valve holes 21 on the valve bottom plate 2, the valve plate 3 and the valve cover plate 4 can be exactly the same or different. In terms of the distribution positions of the valve holes 21, it is only necessary to satisfy that when the valve plate 3 rotates, the holes on the valve bottom plate 2 and the valve cover plate 4 can be in a state of being connected and disconnected from the valve holes 31 on the valve plate 3 in a cyclic and intermittent manner.

[0072] The valve cover plate 4, the valve plate 3 and the valve bottom plate 2 are stacked up and down. In order to make the rotation of the valve plate 3 smoother and reduce the friction during rotation, preferably, a first ball groove 23 is further provided on the upper surface of the valve bottom plate 2;

[0073] Second ball grooves 32 are respectively provided on the upper surface and the lower surface of the valve plate 3 along the circumferential direction;

[0074] A third ball groove 41 is provided on the lower surface of the valve cover plate 4;

[0075] The valve cover plate 4, the valve plate 3 and the valve bottom plate 2 are stacked up and down, and the first ball groove 23, the second ball grooves 32 and the third ball groove 41 are in corresponding positions. Ball bearings 33 are respectively provided in the space between the first ball groove 23 and the second ball grooves 32 and between the second ball grooves 32 and the third ball groove 41.

[0076] In one embodiment, a plurality of first fixing pin holes 42 are circumferentially provided on the outer side of the valve cover plate 4;

[0077] The plurality of first fixing pin holes 42 of the valve cover plate 4 are connected to the valve cover plate fixing threaded holes 13 of the nipple body 1, thereby fixing the valve cover plate 4 to the nipple body 1.

[0078] In one embodiment, in the intelligent anti-cement slurry displacement short joint for cementing, referring to Figure 8 shown, the motor 5 includes: a motor body 52 and a gear 51;

[0079] The output shaft of the motor body 52 is connected to the gear 51; teeth 31 are provided on the outer circumference of the valve plate 3;

[0080] The gear 51 meshes with the teeth 31 on the outer circumference of the valve plate 3.

[0081] Referring to Figure 4 shown, the motor fixing seat 7 is cylindrical, and a motor installation groove 72 and a controller 6 installation groove are provided at the bottom;

[0082] The controller 6 is located in the controller 6 installation groove of the motor fixing seat 7;

[0083] Referring to FIG. 4 and Figure 1 as shown, the top of the motor body 52 of the motor 5 is disposed within the motor mounting groove 72 of the motor fixing base 7, and the gear 51 of the motor 5 is received within the motor gear rotation groove 12 formed at the top of the nipple body 1.

[0084] Referring to Figure 8 as shown, a second fixing pin hole 53 is further provided on the motor body 52 for connection with the motor mounting groove 72 of the motor fixing base 7.

[0085] Referring to Figure 4B as shown, a thread 74 is further provided at the top of the motor fixing base 7.

[0086] Referring to Figure 3A and Figure 3B the schematic structural diagram of the controller 6, the flow guiding groove 64 of the controller 6 is disposed outside the single-chip microcomputer 62, and two voltage detecting pieces 63 are disposed inside the flow guiding groove 64;

[0087] The flow guiding groove 64 has an opening and an outlet, and its opening is larger than the outlet;

[0088] The two voltage detecting pieces 63 are connected in series with resistors to the positive and negative electrodes of the battery 61; the single-chip microcomputer 62 is electrically connected to the two voltage detecting pieces 63.

[0089] The opening of the flow guiding groove 64 is large and the outlet is small, so that the two voltage detecting pieces 63 inside the flow guiding groove 64 can detect the latest wellbore fluid. As the flowing wellbore fluid is different (the resistivity of different wellbore fluids is different), the voltages divided by the two voltage detecting pieces 63 are different. The battery 61 supplies electric energy to the single-chip microcomputer 62, the motor 5 and the voltage detecting pieces 63 respectively, and the voltage detecting pieces 63 are used to detect the voltage between the two pieces.

[0090] Specifically, a program is written inside the single-chip microcomputer 62. When running this program, it calculates the voltage difference between the two voltage detecting pieces 63, compares it with a preset threshold value. If the voltage difference increases and is greater than the preset threshold value, it is determined that the motor 5 needs to be powered on to start the motor, thereby driving the valve plate 3 to rotate.

[0091] In the example shown in FIG. 4, the number of the voltage detecting pieces 63 can be multiple, for example, three. By judging through three detection channels (the voltage differences collected by three detectors), the detection error can be reduced.

[0092] Referring to Figure 9 the example shown is the schematic circuit diagram inside the controller 6. In this schematic circuit diagram, it includes a single-chip microcomputer 62 (80C51), three voltage detecting pieces 63, analog-to-digital converters (ADC08323 and ADC08322). The analog-to-digital converters and the voltage detecting pieces 63 are respectively connected to different pins of the single-chip microcomputer 62.

[0093] Based on the same inventive concept, an embodiment of the present invention further provides a method for using the intelligent anti-cement slurry displacement short joint for well cementing to prompt that the displacement slurry has been completed, and the method includes the following steps:

[0094] First, during the well cementing process, the intelligent anti-cement slurry displacement short joint for well cementing obtains the voltage signals detected by its two voltage detection pieces.

[0095] Second, the intelligent anti-cement slurry displacement short joint for well cementing detects whether the wellbore fluid flowing through changes according to the voltage signals detected by the two voltage detection pieces.

[0096] Third, when it is determined that the displacement slurry has been completed according to the change of the wellbore fluid, the intelligent anti-cement slurry displacement short joint for well cementing controls the motor to drive the valve plate to rotate, so that the valve holes on the valve plate are in a state of cyclically intermittently communicating and non-communicating with the valve holes on the valve bottom plate and the valve cover plate, so as to open and close the casing inner circulation channel, cause the ground pump pressure to fluctuate, and prompt that the displacement fluid has reached the predetermined position.

[0097] For the specific implementation manners of this method, reference can be made to the implementation of the foregoing method, and the repeated parts will not be described again.

[0098] The intelligent anti-cement slurry displacement short joint for well cementing and the method for prompting that the displacement slurry has been completed provided by the embodiment of the present invention can intelligently identify that the displacement slurry has been completed during the well cementing process, and by causing the ground pump pressure to fluctuate, prompt that the displacement fluid has reached the predetermined position, avoiding cement slurry displacement void, thereby ensuring the well cementing quality.

[0099] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories and optical memories, etc.) containing computer-usable program codes.

[0100] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, so that the instructions executed by the processors of the computer or other programmable data processing devices generate for implementing in the process Figure 1 a process or multiple processes and / or blocksFigure 1 means for the functions specified in one or more blocks.

[0101] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction means that implements the functions specified in one or more of the Figure 1 flows or more flows and / or blocks Figure 1 one or more blocks.

[0102] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus, such that a series of operational steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more of the Figure 1 flows or more flows and / or blocks Figure 1 one or more blocks.

[0103] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. An intelligent anti-cement slurry displacement short joint for cementing, characterized in that, Comprising: A short joint body, a valve bottom plate, a valve plate, a valve cover plate, a motor, a controller, and a motor fixing seat; The motor and the controller are arranged inside the motor fixing seat; The motor fixing seat is connected to one end of the short joint body; The inside of the short joint body is a cavity, and the valve bottom plate, the valve plate, and the valve cover plate are sequentially arranged in the cavity inside the short joint; Valve holes are provided on the valve bottom plate, the valve plate, and the valve cover plate, and the valve plate meshes with the output end of the motor; The controller includes two voltage detection pieces, a battery, a single-chip microcomputer, and a diversion groove. The single-chip microcomputer is used to obtain the voltage signals detected by the two voltage detection pieces when the wellbore fluid flows through and collects the diversion groove. According to the voltage signals detected by the two voltage detection pieces, it detects whether the flowing wellbore fluid has changed. When it is determined that the displacement slurry has been completed according to the change of the wellbore fluid, it controls the motor to drive the valve plate to rotate, so that the valve holes on the valve plate are in a state of cyclically intermittently communicating and non-communicating with the valve holes on the valve bottom plate and the valve cover plate, so as to realize opening and closing the inner circulation channel of the casing, causing the ground pump pressure to fluctuate, and indicating that the displacement fluid has reached the predetermined position.

2. The intelligent anti-cement slurry displacement short joint for well cementing according to claim 1, characterized in that The short joint body is cylindrical, and is sequentially provided with connection threads for connecting the lower drill tool, valve bottom plate keyways for connecting the valve bottom plate, motor gear rotation grooves, valve cover plate fixing threaded holes for connecting the valve cover plate, and motor fixing seat fixing threaded holes for connecting the motor fixing seat from bottom to top.

3. The intelligent anti-cement slurry displacement short joint for well cementing according to claim 2, characterized in that, The lower end of the valve bottom plate is provided with a valve bottom plate fixing groove in the circumferential direction, and the valve bottom plate fixing groove is clamped with the valve bottom plate keyway.

4. The intelligent anti-cement slurry displacement short joint for well cementing according to claim 3, characterized in that The valve bottom plate, the valve plate, and the valve cover plate are all disc-shaped and are each provided with at least two valve holes; The upper surface of the valve bottom plate is provided with a first ball groove; The upper surface and the lower surface of the valve plate are respectively provided with second ball grooves in the circumferential direction; The lower surface of the valve cover plate is provided with a third ball groove; The valve cover plate, the valve plate, and the valve bottom plate are stacked up and down, and the first ball groove, the second ball groove, and the third ball groove are in corresponding positions. Balls are respectively arranged in the spaces between the first ball groove and the second ball groove, and between the second ball groove and the third ball groove.

5. The intelligent anti-cement slurry displacement short joint for well cementing according to claim 2, wherein A plurality of first fixing pin holes are circumferentially machined on the outer side of the valve cover plate; The plurality of first fixing pin holes of the valve cover plate are connected to the valve cover plate fixing threaded holes of the short joint body.

6. The intelligent anti-cement slurry displacement short joint for cementing as claimed in claim 2, wherein, The motor includes: a motor body and a gear; The output shaft of the motor body is connected to the gear; teeth are provided on the outer circumference of the valve plate; The gear meshes with the teeth on the outer circumference of the valve plate.

7. The intelligent anti-cement slurry displacement-empty short joint for cementing according to claim 6, wherein The motor fixing seat is cylindrical, and a motor installation groove and a controller installation groove are provided at the bottom; The controller is located in the controller installation groove of the motor fixing seat; The top of the motor body of the motor is arranged in the motor installation groove of the motor fixing seat, and the gear of the motor is accommodated in the motor gear rotation groove provided at the top of the short joint body.

8. The intelligent anti-cement slurry displacement short joint for well cementing according to claim 2, characterized in that Further comprising: The fixing seat threaded hole on the nipple body matches the pin hole on the motor fixing seat, and the nipple body is connected to the motor fixing seat through the fixing seat threaded hole and the pin hole on the motor fixing seat.

9. The intelligent anti-cement slurry displacement short joint for cementing as claimed in any one of claims 1-8, characterized in that, The diversion groove of the controller is arranged outside the single-chip microcomputer, and the two voltage detection pieces are arranged inside the diversion groove; The diversion groove has an opening and an outlet, and its opening is larger than the outlet; The two voltage detection pieces are connected to the positive and negative poles of the battery after being connected in series with resistors; The single-chip microcomputer is electrically connected to the two voltage detection pieces.

10. A method for indicating the completion of slurry displacement using the intelligent anti-cement slurry displacement short joint for cementing as described in any one of claims 1-9, characterized in that, Including: During the cementing process, the intelligent anti-cement slurry displacement short joint for cementing obtains the voltage signals detected by its two voltage detection pieces; The intelligent anti-cement slurry displacement short joint for cementing detects whether the wellbore fluid flowing through changes according to the voltage signals detected by the two voltage detection pieces; When it is determined that the slurry displacement is completed according to the change of the wellbore fluid, the intelligent anti-cement slurry displacement short joint for cementing controls the motor to drive the valve plate to rotate, so that the valve hole on the valve plate is in a state of being intermittently connected and disconnected with the valve holes on the valve bottom plate and the valve cover plate in a cycle, so as to open and close the inner circulation channel of the casing, cause the ground pump pressure to fluctuate, and indicate that the displacement fluid has reached the predetermined position.

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