A near-bit steering system

Abstract

The application discloses a near-bit guiding system, which comprises a guiding short section, a flexible short section, a measurement-while-drilling short section, a central control short section and a pulsing short section. The guiding short section is used for controlling the upper wing ribs thereof by the pressure difference between the inside and outside of the short section through mud to realize directional guiding. The flexible short section is located above the guiding short section. The measurement-while-drilling short section is located above the flexible short section and is used for measuring formation information. The central control short section is located above the measurement-while-drilling short section and is used for sending real-time information request instructions to the guiding short section and the measurement-while-drilling short section respectively when receiving ground instructions. The pulsing short section is located above the central control short section and is used for transmitting the real-time attitude information and the real-time formation information obtained through the central control short section to the ground. The application improves the drilling efficiency and safety.

Description

Technical Field

[0001] This invention relates to the field of drilling equipment technology, and in particular to a near-bit guidance system. Background Technology

[0002] Rotary steering systems are increasingly being used in the exploration and development of complex wells such as extended reach wells, horizontal wells, and highly deviated wells, due to their fast drilling speed, smooth wellbore, and low drilling cost.

[0003] Most existing rotary steering systems are static push-type rotary steering systems with non-rotating sleeves. These systems include guide sections, flexible sections, central control sections, attitude measurement sections, and pulse-generating sections. Some rotary steering systems also connect to drilling-while-drilling (DWD) gamma-ray instruments, DWD resistivity instruments, and DWD sonic instruments. The guide section consists of a rotating shaft and a non-rotating sleeve. The non-rotating sleeve has three ribs controlled by independent hydraulic systems. When the rotary steering system is operating, these three ribs extend under the action of the hydraulic system and contact the wellbore, generating a pushing force. The resultant force of this pushing force is opposite to the target direction, thus propelling the drill bit along the target direction. The pulse-generating section includes a pulse generator and a generator. The generator provides power to the rotary steering system, and the pulse generator is controlled by the control system in the central control section, transmitting data to the surface. The attitude measurement section measures well inclination, azimuth, and other information, transmitting it to the central control section.

[0004] However, in rotary steerable systems with non-rotating sleeves, the non-rotating sleeve rotates very slowly downhole. When encountering softer formations, the pusher ribs may become stuck in the formation, reducing drilling efficiency. Furthermore, the non-rotating sleeve experiences high friction with the wellbore, increasing the risk of stuck pipe. Additionally, this type of rotary steerable system utilizes an independent hydraulic module to drive the extension and retraction of the ribs, resulting in high production and maintenance costs. Moreover, due to system structural limitations, the measurement points for attitude information such as well inclination and azimuth are located relatively far from the drill bit, typically exceeding 8 meters. Summary of the Invention

[0005] The purpose of this invention is to provide a near-drill bit guidance system to solve one or more problems in the prior art.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a near-bit guidance system, comprising: a guide sub connected to the drill bit, used to control its upper ribs by the pressure difference of the drilling mud inside and outside the sub, thereby achieving directional guidance; a flexible sub located above the guide sub; a measurement-while-drilling (MSW) sub located above the flexible sub, used to measure formation information; a central control sub located above the MSW sub, used to send real-time information request commands to the guide sub and the MSW sub respectively upon receiving ground commands; and a pulse transmission sub located above the central control sub, used to transmit real-time attitude information and real-time formation information obtained through the central control sub to the ground.

[0007] Preferably, the flexible short section is constructed in the shape of a dumbbell, which is thicker at both ends and thinner in the middle. The flexible short section has a mud channel and a flexible short section thread hole that runs through both ends is provided on the side wall of the shell. Slip rings are respectively provided at both ends of the flexible short section thread hole.

[0008] Preferably, the guide section includes: a pusher collar connected to the drill bit, the pusher collar having a mud channel; a rib disposed on the side wall of the pusher collar; a directional collar connected to the pusher collar; a pressure-resistant cylinder disposed inside the directional collar, the pressure-resistant cylinder forming a mud channel with the directional collar; a disc valve assembly disposed between the pressure-resistant cylinder and the pusher collar, which is used to control the extension and retraction state of the rib by controlling the opening and closing state of the mud channels at both ends; and an information acquisition and control module disposed inside the pressure-resistant cylinder, which is used to acquire attitude information during drilling in real time and to achieve directional control of the rib by controlling the disc valve assembly.

[0009] Preferably, the disc valve assembly includes: a ribbed motor disposed within the pressure-resistant cylinder, which rotates with the pressure-resistant cylinder; a connecting shaft connected to the ribbed motor; a stationary disc valve fixed on the connecting shaft, which has a first mud hole at its edge; a moving disc valve that rotates with the drill collar, which has multiple second mud holes at its end for controlling the opening and closing of the disc valve assembly when rotating relative to the stationary disc valve; and a diverter connected to the moving disc valve and the push drill collar respectively, for diverting the mud flowing through the moving disc valve to the ribbed mud channel on the side wall of the push drill collar.

[0010] Preferably, the ribs are evenly distributed along the circumferential direction of the sidewall of the push-bearing drill collar, and each rib is provided with a corresponding rib mud hole. The rib mud hole is connected to the rib mud channel on the sidewall of the push-bearing drill collar. The pressure-resistant cylinder is fixed to the center of the directional drill collar by an upper stabilizer and a lower stabilizer. The upper stabilizer is provided with a wire hole, and the sidewall of the pressure-resistant cylinder is provided with a wire hole that communicates with the wire hole of the upper stabilizer.

[0011] Preferably, the information acquisition and control module includes: a circuit skeleton; an attitude sensor mounted on the circuit skeleton, which includes an accelerometer, a rotating gyroscope, and a fluxgate magnetometer; an attitude acquisition circuit mounted on the circuit skeleton, connected to the attitude sensor, for acquiring and storing the real-time attitude information; a guidance control circuit mounted on the circuit skeleton, for receiving and recognizing attitude information request commands to send attitude reading commands to the attitude acquisition circuit, and for receiving and recognizing attitude transmission request commands from the central control section, thereby outputting motor control commands for controlling the rotation angle of the motor output shaft of the disc valve assembly based on the historical attitude information and real-time attitude information sent by the central control section; and a motor drive circuit mounted on the circuit skeleton, for driving the output shaft of the rib motor to rotate to a specified position angle based on the motor control commands, so that the rib at a specific position pushes against the well wall.

[0012] Preferably, the measurement-while-drilling (MWD) sub includes: a MWD sub body with a mud channel; a MWD sub wiring hole disposed on the side wall of the MWD sub body, with slip rings disposed at both ends of the MWD sub wiring hole; and a MWD module disposed on the side wall of the MWD sub body, which is used to receive and identify formation information request commands to feed back real-time formation information to the central control sub.

[0013] Preferably, the pulse generator sub-section includes a pulse generator for transmitting uplink information and ground commands. The central control sub-section comprises: a central control sub-section body; a central control sub-section wiring hole disposed on the side wall of the central control sub-section body, the wiring hole being provided with a slip ring; and an electronic compartment disposed inside the central control sub-section body. The electronic compartment includes: a rectifier circuit connected to the output terminal of the pulse generator, used to rectify the electrical energy of the pulse generator and transmit it to the bus, and to detect changes in the rotational speed of the pulse generator caused by changes in mud flow rate, generating a flow rate change characteristic signal; a decoding circuit, used to identify the flow rate change characteristic signal and obtain the ground commands; and a central control circuit, used to process the ground commands to send time information, attitude transmission request commands, attitude information request commands, and formation information request commands to the bus in a time-division multiplexing manner.

[0014] Preferably, the bus is disposed in the wiring holes of each short section within the near-bit guidance system. The central control circuit sends corresponding request commands to the guidance short section and the measurement while drilling short section, so that each short section triggers an interrupt and responds after receiving the request command about itself, thereby feeding back the requested information.

[0015] Preferably, the measurement-while-drilling instrument is selected from one of the following: a measurement-while-drilling azimuth gamma instrument, a measurement-while-drilling resistivity instrument, a measurement-while-drilling acoustic instrument, and other measurement-while-drilling instruments.

[0016] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0017] This invention proposes a near-bit steering system. The system includes a steering sub, a flexible sub, a measurement-while-drilling (MSW) sub, a central control sub, and a pulse-generating sub. The steering sub has ribs that push against the wellbore, causing the drill bit to deflect in a predetermined direction, thus achieving directional drilling. The flexible sub is dumbbell-shaped, which is beneficial for directional drilling. The MSW sub measures formation information to guide directional drilling. The central control sub receives downlink commands and transmits them to the steering sub via a bus to control the directional drilling direction, as well as receiving data from the steering sub and MSW sub, which is then transmitted to the surface via a pulse generator. The pulse-generating sub provides power to all subs and transmits downhole data to the surface. This invention utilizes the rotating ribs on the steering sub, leveraging the pressure difference of the drilling mud inside and outside the sub to drive the ribs' extension and retraction. Furthermore, the attitude measurement sensor is mounted on the steering sub, reducing costs, shortening the distance between the attitude measurement point and the drill bit, and improving drilling efficiency and safety. In addition, the near-bit steering system provided by this invention is easy to maintain, safe, reliable, and easy to promote and apply.

[0018] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 This is a schematic diagram of the overall structure of the near-drill bit guidance system according to an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the guide section in the near-drill bit guidance system according to an embodiment of this application.

[0022] Figure 3 This is a partial structural schematic diagram of the disc valve assembly in the near-drill bit guidance system according to an embodiment of this application.

[0023] Figure 4 This is a schematic diagram of the flexible short section in the near-drill bit guidance system of this application embodiment.

[0024] Figure 5This is a schematic diagram of the measurement-while-drilling sub in the near-bit guidance system of this application.

[0025] Figure 6 This is a schematic diagram of the structure of the central control sub and the pulse-generating sub in the near-drill bit guidance system of this application embodiment.

[0026] Figure 7 This is a schematic diagram of the overall circuit connection of the near-drill bit guidance system according to an embodiment of this application. Detailed Implementation

[0027] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0028] Furthermore, the steps illustrated in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in a different order than that shown here.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0030] Rotary steering systems are increasingly being used in the exploration and development of complex wells such as extended reach wells, horizontal wells, and highly deviated wells, due to their fast drilling speed, smooth wellbore, and low drilling cost.

[0031] Most existing rotary steering systems are static push-type rotary steering systems with non-rotating sleeves. These systems include guide sections, flexible sections, central control sections, attitude measurement sections, and pulse-generating sections. Some rotary steering systems also connect to drilling-while-drilling (DWD) gamma-ray instruments, DWD resistivity instruments, and DWD sonic instruments. The guide section consists of a rotating shaft and a non-rotating sleeve. The non-rotating sleeve has three ribs controlled by independent hydraulic systems. When the rotary steering system is operating, these three ribs extend under the action of the hydraulic system and contact the wellbore, generating a pushing force. The resultant force of this pushing force is opposite to the target direction, thus propelling the drill bit along the target direction. The pulse-generating section includes a pulse generator and a generator. The generator provides power to the rotary steering system, and the pulse generator is controlled by the control system in the central control section, transmitting data to the surface. The attitude measurement section measures well inclination, azimuth, and other information, transmitting it to the central control section.

[0032] However, in rotary steerable systems with non-rotating sleeves, the non-rotating sleeve rotates very slowly downhole. When encountering softer formations, the pusher ribs may become stuck in the formation, reducing drilling efficiency. Furthermore, the non-rotating sleeve experiences high friction with the wellbore, increasing the risk of stuck pipe. Additionally, this type of rotary steerable system utilizes an independent hydraulic module to drive the extension and retraction of the ribs, resulting in high production and maintenance costs. Moreover, due to system structural limitations, the measurement points for attitude information such as well inclination and azimuth are located relatively far from the drill bit, typically exceeding 8 meters.

[0033] To address the aforementioned technical problems, this application proposes a near-bit guidance system. The ribs on the guide section of this system rotate with the section, and the pressure difference between the mud inside and outside the section drives the ribs to extend and retract. Furthermore, the attitude measurement sensor is mounted on the guide section, reducing costs, shortening the distance between the attitude measurement point and the drill bit, and improving drilling efficiency and safety.

[0034] Figure 1 This is a schematic diagram of the overall structure of the near-drill bit guidance system according to an embodiment of this application. Figure 1 As shown, the near-bit guidance system of this embodiment includes: a guide sub 100, a flexible sub 200, a measurement-while-drilling (MSW) sub 300, a central control sub 400, and a pulse-generating sub 500. The guide sub 100 is connected to the drill bit 101 at its lower end, and to the flexible sub 200 at its upper end. The MSW sub 300 is connected to the flexible sub 200 at its lower end, the central control sub 400 is connected to the MSW sub 300 at its lower end, and the pulse-generating sub 500 is connected to the central control sub 400 at its lower end.

[0035] In this embodiment of the invention, the short sections 100, 200, 300, 400, and 500 are connected by modified API buckles, and each modified buckle is equipped with a single-wire slip ring on its end face so that the single-wire slip ring can be used to transmit electrical energy and signals between the short sections.

[0036] The guide sub 100 is used to control the ribs on the guide sub 100 by utilizing the pressure difference of the drilling mud inside and outside the sub, thereby achieving directional guidance. Additionally, the guide sub 100 is used to measure real-time attitude information during the guidance process. A flexible sub is used to achieve a flexible connection between the guide sub 100 and the measurement-while-drilling (MSW) sub 300. The MSW sub 300 is used to measure formation information. The central control sub 400 is used to send real-time information request commands to both the guide sub 100 and the MSW sub 300 upon receiving ground commands, so that when the guide sub 100 and the MSW sub 300 receive their own real-time measurement information request commands, they will feed back their measured real-time attitude and formation information to the central control sub 400. Finally, the pulse-generating sub 500 is used to transmit the real-time attitude and formation information obtained through the central control sub 400 to the ground.

[0037] The specific structure and function of each section in the near-bit guidance system are explained below.

[0038] Figure 2 This is a schematic diagram of the guide section in the near-drill bit guidance system according to an embodiment of this application. Figure 2 As shown, the guide sub 100 includes: a push drill collar 110, ribs 111, a directional drill collar 120, a pressure-resistant cylinder 121, and a disc valve assembly (unnumbered). It should be noted that... Figure 2 The right side is the lower end of the short section, and the left side is the upper end of the short section.

[0039] The push drill collar 110 is connected to the drill bit 101 and has a mud channel 180. A rib 111 is located on the side wall of the push drill collar 110. A directional drill collar 120 is connected to the push drill collar 110. The directional drill collar 120 and the push drill collar 110 are fixedly connected via API standard fasteners. A pressure-resistant cylinder 121 is located inside the directional drill collar 120. A mud channel 180 is formed between the pressure-resistant cylinder 121 and the directional drill collar 120. A disc valve assembly is located between the pressure-resistant cylinder 121 and the push drill collar 110. The disc valve assembly controls the extension and retraction of the rib 111 by controlling the opening and closing of the mud channels at both ends (upper and lower). An information acquisition and control module (unnumbered) is located inside the pressure-resistant cylinder 121. The information acquisition and control module is used to acquire attitude information during drilling in real time, and to achieve directional control of the wing rib 111 by controlling the disc valve assembly.

[0040] In one embodiment, the guide section 100 of the present invention includes a plurality of ribs 111, each rib 111 being evenly distributed along the circumferential direction of the side wall of the drill collar 110, and each rib 111 having a corresponding rib mud hole below it, each rib mud hole being connected to the rib mud channel 112 on the side wall of the drill collar 110.

[0041] Furthermore, the pressure-resistant cylinder 121 is fixed to the center of the directional drill collar 120 via the upper stabilizer 123 and the lower stabilizer 122. The upper stabilizer 123 is provided with a wire hole 124. The side wall of the pressure-resistant cylinder 121 is provided with a wire hole 125 that communicates with the wire hole 124 of the upper stabilizer 123.

[0042] Figure 3 This is a partial structural schematic diagram of the disc valve assembly in the near-drill bit guidance system according to an embodiment of this application. The following is in conjunction with... Figure 2 and Figure 3 The structure of the disc valve assembly described in the embodiments of the present invention will be explained. For example... Figure 2 As shown, the disc valve assembly includes: a ribbed motor 138, a connecting shaft 140, a stationary disc valve 143, a moving disc valve 142, and a flow divider 141. The ribbed motor 138 is disposed inside the pressure-resistant cylinder 121 and rotates with the pressure-resistant cylinder 121. The connecting shaft 140 is connected to the ribbed motor 138. The stationary disc valve 143 is fixed to the connecting shaft 140. Figure 3 As shown, a first mud hole 145 is provided at the edge of the stationary disc valve 143. The moving disc valve 142 rotates with the drill collar. Figure 3 As shown, multiple second mud holes 144 penetrating the body of the moving disc valve 142 are provided on the end face of the moving disc valve 142. The moving disc valve 142 is coaxial with and rotates relative to the stationary disc valve 143. The moving disc valve 142 is used to control the opening and closing action of the disc valve assembly when rotating relative to the stationary disc valve 143. (See again...) Figure 2 The upper and lower ends of the diverter 144 are connected to the moving disc valve 142 and the push drill collar 110, respectively. The diverter 144 is used to divert the mud flowing through the moving disc valve 142 to the ribbed mud channel 112 on the side wall of the push drill collar 110.

[0043] In this embodiment of the invention, three sets of ribs 111 are provided, evenly distributed along the circumference on the push-fit drill collar 110, rotating with the push-fit drill collar 110. When a set of ribs 111 rotates to a designated direction, it extends and pushes against the well wall, subjecting the drill bit to a lateral pushing force, thereby achieving guidance. When the set of ribs 111 deviates from the designated direction, it retracts under the action of the well wall. The extension and retraction of the ribs 111 is driven by the mud in the mud channel 180. The mud in the mud channel 180 is introduced into the rib mud channel 112 below the ribs 111. Because the mud pressure in the mud channel 180 is higher than the mud pressure in the annulus, the ribs 111 extend under the pressure difference. The opening and closing of the rib mud channel 112, which is connected to the rib mud hole below the ribs 111, is controlled by a disc valve assembly.

[0044] In one embodiment, the moving disc valve 142 is provided with three mud holes 144, which are evenly distributed along the circumference. The moving disc valve 142 is installed at the rear end of the distributor 141, and each mud hole 144 is connected to a corresponding mud hole on a rib below a set of ribs. That is, in this embodiment of the invention, the number of ribs 111 is matched with the number of second mud holes 144 on the moving disc valve 142.

[0045] The stationary disc valve 143 has a first mud hole 145. The moving disc valve 142 rotates with the drill collar, while the stationary disc valve 143 does not rotate relative to the formation. The moving disc valve 142 and the stationary disc valve 143 are coaxial and rotate relative to each other. When a mud hole 144 on the moving disc valve 142 coincides with a mud hole 145 on the stationary disc valve 143, the disc valve assembly opens, and mud enters below the corresponding rib 111, pushing the rib 111 out. When no mud hole 144 on the moving disc valve 142 coincides with a mud hole 145 on the stationary disc valve 143, the disc valve assembly closes, and the rib 111 retracts.

[0046] A stationary valve 143 is fixedly connected to a connecting shaft 140, which is controlled by a rib motor 138. The rib motor 138 is fixedly installed inside a pressure-resistant cylinder 121 and rotates with it. The pressure-resistant cylinder 121 is fixedly installed inside a directional drill collar 120 and rotates with it. The pressure-resistant cylinder 121 has a lower stabilizer 122 and an upper stabilizer 123, which fix the pressure-resistant cylinder 121 in the center of the directional drill collar 120. A wiring groove 126 is provided on the side wall of the directional drill collar 120, with both ends communicating with a through hole 124 in the upper stabilizer 123 and a through hole 125 on the side wall of the directional drill collar 120, respectively. In addition, a guide section cover 127 is provided on the guide section 100, which covers the wiring groove 126 to prevent mud from entering. A slip ring 160 is provided at the upper end of the directional drill collar 120 (i.e., the inlet end of the wiring hole 125). The slip ring 160 is connected to the single-core cable bus 600, which enters the pressure-resistant cylinder 121 through the wiring hole 125, wiring groove 126, and wiring hole 124, connecting to the information acquisition and control module. The information acquisition and control module is fixedly installed inside the pressure-resistant cylinder 121.

[0047] refer to Figure 2 and Figure 7 The information acquisition and control module includes: a circuit frame 151, an attitude sensor 137, an attitude acquisition circuit 135, a guidance control circuit 134, and a motor drive circuit 136. The circuit frame 151 is fixedly installed inside the pressure-resistant cylinder 121, and the wing-rib motor 138 is fixedly connected to the circuit frame 151 by bolts. The attitude sensor 137, attitude acquisition circuit 135, guidance control circuit 134, and motor drive circuit 136 are fixedly mounted on the circuit frame 151.

[0048] Attitude sensor 137 includes an accelerometer, a rotating gyroscope, and a fluxgate magnetometer to detect attitude information (including inclination angle, azimuth angle, rotational speed, etc.) in real time during the drilling process. Attitude acquisition circuit 135 is connected to attitude sensor 137 to acquire and store real-time attitude information. Guiding control circuit 134 receives and identifies attitude information request commands from central control sub 400 to send attitude read commands to attitude acquisition circuit 135, thereby obtaining the real-time attitude information sent by attitude acquisition circuit 135. In addition, guiding control circuit 134 also receives and identifies attitude transmission request commands from central control sub 400, and outputs motor control commands to control the rotation angle of the rib motor output shaft of the disc valve assembly based on historical attitude information sent by central control sub 400 and locally stored real-time attitude information. Motor drive circuit 136 drives the output shaft of rib motor 138 to rotate to a specified position angle (indicated in the surface command) based on the motor control commands, so that the rib 111 at a specific position pushes against the well wall.

[0049] In addition, the information acquisition and control module also includes a small battery 132, a guide section bus circuit 131, and a guide section power conversion circuit 133, all fixedly mounted on the circuit frame 151. The guide section bus circuit 131 is located between the bus 600 and the guide control circuit 134, and is used for encoding / decoding and level conversion matching of instructions or information transmitted between the bus 600 and the guide control circuit 134. The guide section power conversion circuit 133 converts the power signals provided on the bus 600 into power signals of different levels to power the various circuits inside the guide section. The small battery 132 serves as a backup power source for the guide section 100.

[0050] Specifically, the power conversion circuit 133 on the guide section 100 is connected to the bus 600, obtaining 30-48VDC direct current from the bus 600 and converting it into the voltage required by each circuit board on the guide section 100, such as +5VDC or ±12VDC, to power the bus circuit 131, the guidance control circuit 134, the attitude acquisition circuit 135, and the motor drive circuit 136. The motor drive circuit 136 is connected to the bus 600, obtaining 30-48VDC direct current from the bus 600 to power the wing motor 138. A guide section inductor 604 is provided between the power conversion circuit 133, the motor drive circuit 136, and the bus 600, which serves to block AC and allow DC to pass. The attitude acquisition circuit 135 powers the attitude sensor 137. Small battery 132 serves as a backup power source. When there is no power on the bus 600, small battery 132 supplies power to attitude acquisition circuit 135, maintaining the normal operation of attitude acquisition circuit 135 and attitude sensor 137. Attitude sensor 137 consists of sensors such as accelerometer, gyroscope, and fluxgate magnetometer. Attitude acquisition circuit 135 processes the data measured by attitude sensor 137. When guidance control circuit 134 requests data from attitude acquisition circuit 135, attitude acquisition circuit 135 transmits the processed real-time attitude data to guidance control circuit 134. Based on the data processed by attitude acquisition circuit 135, guidance control circuit 134 further controls motor drive circuit 136 to drive wing rib motor 138 to rotate, thereby controlling disc valve assembly. Bus circuit 131 is connected to bus 600, decodes the data on bus 600, and transmits it to guidance control circuit 134. Guiding control circuit 134 identifies the received commands and responds accordingly. When the instruction on the bus 600 is an instruction about the guide section itself (attitude information request instruction or attitude transmission request instruction), the guide control board 134 sends the measured real-time attitude information to the bus circuit 131, which encodes it and transmits it to the bus 600 for reception by the central control section 400.

[0051] Figure 4This is a schematic diagram of the flexible short section in the near-drill bit guidance system according to an embodiment of this application. Figure 4 As shown, the flexible short section 400 is constructed in a dumbbell shape, thicker at both ends and thinner in the middle. The flexible short section 400 has a mud channel inside, and a flexible short section through hole 210 with both ends through it is provided on the side wall of the shell. An upper slip ring 260 and a lower slip ring 261 are respectively provided at both ends of the flexible short section through hole 210.

[0052] refer to Figure 4 The flexible short section 200 is fixedly connected to the directional drill collar 120 via API clips, with the flexible short section 200 located at the upper end. Both ends of the flexible short section 200 are equipped with an upper slip ring 260 and a lower slip ring 261, with the lower slip ring 261 connected to a slip ring 160 on the directional drill collar 120. A single-core cable bus 600 is installed inside the flexible short section's cable hole 210, with both ends of the single-core cable bus 600 electrically connected to the upper slip ring 260 and the lower slip ring 261, respectively.

[0053] Figure 5 This is a schematic diagram of the measurement-while-drilling sub in the near-bit guidance system of this application. Figure 5 As shown, the measurement-while-drilling sub 300 includes: the measurement-while-drilling sub body (unnumbered), the measurement-while-drilling sub wiring holes 301 and 302, and the measurement-while-drilling instrument (unnumbered).

[0054] The measurement-while-drilling (MSW) sub has a mud channel inside. The MSW sub has wiring holes 301 and 302 on its sidewall. Slip rings are provided at both ends of these wiring holes. The MSW instrument is mounted on the sidewall of the MSW sub. The MSW instrument receives and identifies formation information request commands from the central control sub 400, and feeds back real-time formation information to the central control sub 400. In this embodiment, the MSW instrument is selected from one of the following: a drilling azimuth gamma ray instrument, a drilling resistivity instrument, a drilling acoustic instrument, and other drilling instruments.

[0055] like Figure 5 As shown, the measurement-while-drilling (MWD) sub 300 and the flexible sub 200 are fixedly connected by API clips, with the MWD sub 300 at the upper end. An upper slip ring 360 and a lower slip ring 361 are installed in the cable-passing holes on the side wall of the MWD sub 300, and the lower slip ring 361 is connected to the upper slip ring 260 of the flexible sub 200. Cable-passing holes 301 and 302 are provided on the side wall of the MWD sub 300 body, and single-core cable buses 600 are installed in the cable-passing holes 301 and 302, respectively, and the single-core cable buses 600 are connected to the upper slip ring 360 and the lower slip ring 361.

[0056] A measurement-while-drilling (MSW) module is mounted on the side wall of the measurement-while-drilling sub 300 body. The MSW module includes, but is not limited to, the MSW bus circuit 321, the MSW power conversion circuit 322, the MSW sub control circuit 323, and other circuit boards of the MSW instrument. Cover plates 311 and 312 are externally fixedly mounted on the MSW module to protect the circuit boards.

[0057] The measurement-while-drilling (MSW) bus circuit 321 is located between the bus 600 and the MSW control sub 323, and is used for encoding / decoding and level conversion matching of command or information transmission between the bus 600 and the MSW control sub 323. The MSW power conversion circuit 322 converts the power signal provided on the bus 600 into power signals of different levels to power the various circuits inside the MSW sub 300. The MSW control sub 323 receives and identifies formation information request commands to feed back the real-time acquired formation information to the central control sub 400.

[0058] The measurement-while-drilling (MSW) power conversion circuit 322 is connected to the bus 600, receiving 30-48VDC DC power from the bus 600 and converting it into the voltage required by the MSW sub 300, such as +5VDC or ±12VDC, to power the bus circuit 321, the MSW sub control circuit 323, and other circuits. A MSW inductor 604 is installed between the MSW power conversion circuit 322 and the bus 600 to block AC and allow DC transmission. The MSW bus circuit 321 is connected to the bus 600, decoding data or commands related to the MSW sub itself on the bus 600 and transmitting them to the MSW sub control circuit 323. Upon receiving a command, the MSW sub control circuit 323 sends the measured real-time formation information to the MSW bus circuit 321, which encodes and transmits it back to the bus 600 for reception by the central control sub 400.

[0059] Figure 6 This is a schematic diagram of the central control sub and the pulse-generating sub in the near-bit guidance system of this application. Figure 6 As shown, the central control unit 400 includes a central control unit body (unnumbered), a central control unit wiring hole 401, and an electronic compartment 410. The central control unit wiring hole 401 is located on the side wall of the central control unit body, and a slip ring 461 is installed inside the central control unit wiring hole 401. The electronic compartment is located inside the central control unit body.

[0060] like Figure 6As shown, the central control sub 400 and the pulse generator sub 500 are fixedly connected via API clips, with the pulse generator sub 500 at the upper end. The central control sub 400 and the measurement-while-drilling sub 300 are fixedly connected via API clips, with the central control sub 400 at the upper end. A wiring hole 401 is provided on the side wall of the central control sub 400 body. A single-core cable bus 600 is installed inside the wiring hole 401, and a slip ring 461 is installed inside the wiring hole 401. The slip ring 461 is electrically connected to the upper slip ring 360 of the measurement-while-drilling sub 300. The two ends of the bus 600 inside the central control sub 400 are electrically connected to the slip ring 461 and the internal circuitry of the electronic compartment inside the central control sub 400, respectively. Additionally, a wiring groove 402 for wiring is provided on the side wall of the central control sub 400 body. A cover plate 412 is used to cover the wiring groove 402 to prevent mud from entering the interior of the central control sub 400.

[0061] Continue to refer to Figure 6 The pulse generator subsection 500 includes a pulse generator 510 for transmitting uplink information and ground commands. Additionally, the pulse generator subsection 500 includes a guide head 411 and a cable passage 413 for electrically connecting the pulse generator 510 to the central control subsection 400. The guide head 411 and the cable passage 413 are located at the central axis of the pulse generator subsection 500. The guide head 411 communicates with the cable passage 413 and contains a lead wire (not shown) for connecting the pulse generator 510 to the central control subsection 400. The pulse generator 510 is fixedly installed inside the pulse generator subsection 500 and is electrically connected to the electronics compartment 410 inside the central control subsection 400 through the cable passage 413 in the guide head 411.

[0062] Furthermore, an electronic compartment 410 is fixedly installed inside the central control section 400. The electronic compartment 410 contains a rectifier circuit 431, a decoder circuit 434, and a central control circuit 435. The rectifier circuit 431, the decoder circuit 434, and the central control circuit 435 are mounted on the electronic compartment 410.

[0063] The rectifier circuit 431 is connected to the output terminal of the pulse generator 510. The rectifier circuit 431 is used to rectify the electrical energy output by the pulse generator 510 (obtaining DC power) and transmit it to the bus 600. Additionally, the rectifier circuit 431 is also used to detect changes in the rotational speed of the pulse generator 510 and generate a flow rate change characteristic signal. The change in the rotational speed of the pulse generator 510 is generated by controlling the mud flow rate changes through ground equipment. The decoding circuit 434 is connected to the rectifier circuit 431 and is used to identify the flow rate change characteristic signal and obtain ground commands. The central control circuit 435 is connected to the decoding circuit 434 and is used to process the obtained ground commands to send time information, attitude transmission request commands, attitude information request commands, and formation information request commands to the bus 600 in a time-division multiplexing manner.

[0064] In addition, the electronic compartment 410 also includes a central control sub-section bus circuit 433 and a central control sub-section power conversion circuit 432. The central control sub-section bus circuit 433 and the central control sub-section power conversion circuit 432 are installed on the electronic compartment 410. The central control sub-section bus circuit 433 is located between the bus 600 and the central control circuit 435, and is used for encoding / decoding and level conversion matching of instruction or information transmission between the bus 600 and the central control circuit 435. The central control sub-section power conversion circuit 432 is connected to the output of the rectifier circuit 431, and is used to convert the DC power signal output by the rectifier circuit 431 into power signals of different levels to power the various circuits inside the central control sub-section.

[0065] In practical applications, the electrical energy generated by the pulse generator 510 is rectified into a 30-48VDC DC power signal by the rectifier circuit 431. The rectifier circuit 431 is connected to the bus 600, transmitting the DC power to the bus 600. Additionally, a central control short section inductor 603 is installed between the rectifier circuit board 431 and the bus 600, serving to block AC and allow DC to pass. The rectifier circuit 431 provides a DC power signal to the central control short section power conversion circuit 432, which converts the 30-48VDC DC power signal into +5VDC DC power to provide +5VDC DC power to the bus circuit 433, decoding circuit 434, and control circuit 435. The rectifier circuit 431 is also used to detect changes in the generator 510's rotational speed. The ground equipment controls the generator 510's rotational speed by controlling the mud flow rate. After the ground commands are encoded, they are transmitted by the ground equipment through the control of mud flow rate changes. The rectifier circuit 431 transmits the detected flow rate change characteristic signal to the decoding circuit 434, which decodes the flow rate change and then transmits the ground commands to the central control circuit 435. The central control circuit 435 converts the ground commands into various secondary control commands for the control guidance sub 100 and the measurement while drilling sub 300, and sends the commands to be transmitted to the central control sub bus circuit 433. The central control sub bus circuit 433 encodes the secondary control commands (e.g., transmission time information, attitude transmission request commands, attitude information request commands, and formation information request commands) and transmits them to the bus 600. Data, information, or signals transmitted on the measurement-while-drilling sub 300 and / or guide sub 100 transmission bus 600 are received and decoded by the bus circuit 433, and then fed back to the central control circuit 435. The central control circuit 435 processes and responds to store the processed data in the storage chip on the central control circuit 435. Then, the data required by the ground (e.g., real-time attitude information and real-time formation information) is encoded and transmitted to the pulse generator 510, so that the pulse generator 510 can transmit the data back to the ground.

[0066] Furthermore, the single-core cable bus 600 is installed in the threading holes of each short section within the near-drill bit guide system. Figure 7 This is a schematic diagram of the overall circuit connection of the near-drill bit guidance system according to an embodiment of this application. Figure 7 As shown, the single-core cable in the wiring hole 125 in the guide section 100, the wiring hole 210 in the flexible section 200, the wiring holes 301 and 302 in the measurement-while-drilling section 300, and the wiring hole 401 in the central control section 400; and the slip ring 160 in the guide section 100, the upper slip ring 260 and the lower slip ring 261 in the flexible section 200, the upper slip ring 360 and the lower slip ring 361 in the measurement-while-drilling section 300, and the slip ring 461 in the central control section 400 together form a complete bus 600. The single-core cable bus 600 transmits electrical energy and signals. Among them, Figure 7 The dashed connecting line 601 in the diagram represents a signal line in the guide system circuit section. Figure 7 The solid line 602 in the diagram represents the power line in the guide system circuit section.

[0067] In addition, the central control circuit 435 sends corresponding request commands to the guide sub 100 and the measurement while drilling sub 300, so that each sub triggers an interrupt and responds after receiving the request command about itself, thereby feeding back the requested information.

[0068] In one specific embodiment, after the near-bit steerable system begins operation in the well, the mud circulates normally, the generator 510 starts working, supplying power to the internal components of the rotary steerable system, and all circuits are energized. The circuits in the steerable sub 100 are initialized and await instructions from the bus 600. The measuring instruments in the measurement-while-drilling sub 300 also begin working and await instructions from the bus 600.

[0069] After the central control circuit 435 in the central control section 400 completes initialization, it reads the time from the clock chip on the central control circuit 435 and encodes it. Then, it transmits the time information command that the central control circuit 435 needs to transmit to the bus 600 through the bus circuit 433. The encoded time information command consists of address + identifier + time value + end bit + check bit, for example, #010000xxxxxxxxxxxx**XX, where #01 represents the common address, 0000 represents the time identifier, xxxxxxxxxxxx represents the value of year, month, day, hour, minute, and second, ** is the end bit, and XX is the value of the check bit.

[0070] The measurement-while-drilling (MWD) sub control circuit 323 in the MWD sub 300 controls the operation of other circuits within the MWD sub 300 to acquire formation resistivity information. When there is information on the bus 600, an interrupt is triggered in the MWD sub control circuit 323, which then receives instruction information from the bus 600. After receiving a complete message, the received data is verified according to the verification rules. If the data is correct, the address and identifier of the instruction information are determined. If it is #010000, the time value is received, and the time information of the MWD sub control circuit 323 itself is updated accordingly.

[0071] After the guide control circuit 134 in the guide section 100 is powered on, it sends a command to the motor drive circuit 136 to control the output shaft of the rib motor 138 to return to the zero position. At this time, the disc valve assembly is closed, and the motor output shaft rotates together with the motor 138. When there is information on the bus 600, the guide control circuit 134 is interrupted, and the guide control circuit 134 receives the command information on the bus 600. After receiving a complete message, it first verifies the received data according to the verification rules. If the data is correct, it determines the address and identifier of the message. If it is #010000, it receives the time value and updates its own time information according to the time.

[0072] When the formation command is transmitted, after the decoding circuit 434 detects a change in mud flow rate through the rectifier circuit 431, it sends an interrupt command to the central control circuit 435. Upon receiving the interrupt command, the central control circuit 435 stops working and waits for the decoding circuit 434 to send a complete surface command (which includes specified angle information for controlling the rib 111 to rotate to the target position). At this time, the pulser 510 stops working, and the central control circuit 435 no longer receives data from the bus 600. After the decoding circuit 434 sends the surface command to the central control circuit 435, the central control circuit 435 begins to control the guide sub 100 to complete the directional guidance task and complete the task of requesting real-time downhole data.

[0073] Then, the central control circuit 435 reads the historical attitude information stored in the storage chip, including the well inclination angle and azimuth angle, encodes the historical attitude information, and then sends the attitude transmission request command containing the historical attitude information to the bus 600. The structure of the encoded attitude transmission request command is the same as that of the time information, for example, #020011xxxxxxxxxxxx**XX, where #02 represents the address of the guidance control circuit 134, 0011 represents the historical attitude information sent by the central control circuit 435, and xxxxxxxxxxxx represents the values ​​of the historical attitude information such as the well inclination angle and azimuth angle. At this time, the central control circuit 435 waits for the response from the guidance control circuit 134. If the central control circuit 435 does not receive a response after 1 second, or if the received response is incorrect, it resends the attitude transmission request command containing the historical attitude information; if a correct response is received, it sends the next command.

[0074] When information is received on bus 600, the guidance control circuit 134 is interrupted, and it receives the attitude transmission request command from bus 600. After receiving a complete message, the guidance control circuit 134 first verifies the received command information according to the verification rules. If the data is correct, it determines the address and identifier of the message. If it is #020011, the guidance control circuit 134 sends a response message to the central control circuit 435. Then, it reads the real-time attitude information from the attitude acquisition circuit 135 and compares it with the historical attitude information from the central control section 400 to calculate the rotation angle of the output shaft of the wing rib motor 138. It then sends a motor control command to the motor drive circuit 136 to control the output shaft of the wing rib motor 138 to rotate to the specified position angle. Subsequently, the motor drive circuit 136 also controls the output shaft of the wing rib motor 138 to rotate at the same speed but in the opposite direction based on the rotation speed information. At this time, the output shaft of the wing rib motor 138 remains at the specified angle.

[0075] Next, the central control circuit 435 sends a pose information request command to the guidance control circuit 134. The command format is #020022xxxxxxxxxxxx**XX, where #02 represents the address of the guidance control board 134, 0022 represents the attitude information sent by the guidance control circuit 134, and xxxxxxxxxxxx represents the values ​​of real-time attitude information such as well inclination angle and azimuth angle. Then, the central control circuit 435 waits for a response from the guidance control circuit 134. If the central control circuit 435 does not receive a response after 1 second, or if the received response is incorrect, it resends the pose information request command. If a correct response is received, it waits for the guidance control circuit 134 to send real-time attitude information. Then, if the central control circuit 435 does not receive real-time attitude information within 1 second, or if the received attitude information is incorrectly verified, it resends the pose information request command to the guidance control circuit 134.

[0076] When information is received on bus 600, an interrupt is triggered in the guidance control circuit 134, which then receives the information from bus 600. After receiving a complete message, the circuit first verifies the data according to the verification rules. If the data is correct, it checks the address and identifier of the message. If it is #020022, it sends a response message to the central control circuit 435. Then, it reads real-time attitude information such as well inclination, azimuth, and rotational speed from the attitude acquisition circuit 135 and feeds this real-time attitude information back to the central control circuit 435. The format of the fed-back real-time attitude information is #040022xxxxxxxxxxxx**XX, where #04 represents the address of the central control circuit 435, and 0022 represents the real-time attitude information sent by the guidance control circuit 134. Furthermore, after the interrupt instruction is executed, the guidance control circuit 134 continues the attitude measurement work performed before the interrupt.

[0077] Once the central control circuit 435 receives the correct attitude information, it stores the real-time attitude information into the memory chip and then sends the next instruction.

[0078] Furthermore, the central control circuit 435 sends a formation information request command to the measurement-while-drilling (MWD) sub control circuit 323. The command format is #030033xxxxxxxxxxxx**XX, where #03 represents the address of the MWD sub control circuit 323, 0033 represents the resistivity information sent by the MWD sub control circuit 323, and xxxxxxxxxxxx is the resistivity value. Then, the central control circuit 435 waits for a response from the MWD sub control circuit 323. If the central control circuit 435 does not receive a response after 1 second, or if the received response is incorrect, it resends the formation information request command. If a correct response is received, it waits for the MWD sub control board 323 to send real-time formation information. Then, if the central control circuit 435 does not receive real-time formation information within 1 second, or if the received real-time formation information has a verification error, it resends the formation information request command to the MWD sub control circuit 323.

[0079] When information is received on bus 600, an interrupt is triggered in the measurement-while-drilling (MWD) sub control circuit 323, which then receives the information from bus 600. After receiving a complete message, the circuit first verifies the received instruction information according to the verification rules. If the data is correct, it determines the address and identifier of the message. If it is #030033, it first sends a response message to the central control circuit 435, and then sends the real-time measured formation information to the central control circuit 435. The format of the real-time formation information is #040033xxxxxxxxxxxx**XX, where #04 represents the address of the central control circuit 435, and 0033 represents the real-time resistivity information sent by the MWD sub control circuit 323. After the interrupt instruction execution is completed (e.g., time configuration or sending real-time resistivity information), the MWD sub control circuit 323 resumes the formation measurement work performed before the interrupt.

[0080] Once the central control circuit 435 receives the correct real-time formation information, it stores the information in the memory chip. Then, it encodes the received real-time attitude and formation information, and controls the pulse generator 510 to send attitude and resistivity information (i.e., attitude and formation information) to the ground. After the attitude and resistivity information are sent, the central control circuit 435 resends an attitude information request command to the guidance control circuit 134 and a formation information request command to the measurement-while-drilling sub control circuit 323. Then, it continues to control the pulse generator 510 to send real-time data to the ground.

[0081] This invention discloses a near-bit steering system. The system includes a steering sub, a flexible sub, a measurement-while-drilling (MSW) sub, a central control sub, and a pulse-generating sub. The steering sub has ribs that push against the wellbore, causing the drill bit to deflect in a predetermined direction, thus achieving directional drilling. The flexible sub is dumbbell-shaped, which is beneficial for directional drilling. The MSW sub measures formation information to guide directional drilling. The central control sub receives downlink commands and transmits them to the steering sub via a bus to control the directional drilling direction, as well as receiving data from the steering sub and MSW sub, which is then transmitted to the surface via a pulse generator. The pulse-generating sub provides power to all subs and transmits downhole data to the surface. This invention utilizes the rotating ribs on the steering sub, leveraging the pressure difference of the drilling mud inside and outside the sub to drive the ribs' extension and retraction. Furthermore, the attitude measurement sensor is mounted on the steering sub, reducing costs, shortening the distance between the attitude measurement point and the drill bit, and improving drilling efficiency and safety. In addition, the near-bit steering system provided by this invention is easy to maintain, safe, reliable, and easy to promote and apply.

[0082] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0083] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0084] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0085] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0086] The phrase "an embodiment" or "an embodiment" used in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0087] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A near-drill bit guidance system, characterized in that, include: A guide sub, connected to the drill bit, is used to control the upper ribs of the drill bit through the pressure difference of the mud inside and outside the sub to achieve directional guidance. The guide sub includes an information acquisition and control module installed inside the pressure-resistant cylinder. The information acquisition and control module includes a guide control circuit and a motor drive circuit installed on the circuit frame. The guide control circuit is used to receive and identify attitude information request commands to send attitude reading commands to the attitude acquisition circuit, and to receive and identify attitude transmission request commands from the central control sub. Based on the historical attitude information and real-time attitude information sent by the central control sub, it outputs motor control commands to control the rotation angle of the motor output shaft of the disc valve assembly. The motor drive circuit is used to drive the output shaft of the rib motor to rotate to a specified position angle based on the motor control commands, so that the ribs at a specific position push against the well wall. A flexible short section is located above the guide short section; A measurement-while-drilling sub, located above the flexible sub, is used to measure formation information; The central control section, located above the measurement-while-drilling (MWD) section, is used to send real-time information request commands to both the guide section and the MWD section upon receiving ground commands. The central control section includes an electronic compartment within its body, which contains a central control circuit. This circuit processes the ground commands to send time information, attitude transmission request commands, attitude information request commands, and formation information request commands to the bus in the wiring holes of each section within the near-bit guidance system, in a time-division manner. By sending corresponding request commands to the guide section and the MWD section, the central control circuit enables each section to trigger an interrupt and respond upon receiving its own request command, thus providing feedback on the requested information. The pulse-generating sub-junction, located above the central control sub-junction, is used to transmit real-time attitude information and real-time formation information obtained through the central control sub-junction to the ground.

2. The near-bit guidance system according to claim 1, characterized in that, The flexible short section is constructed in the shape of a dumbbell, which is thicker at both ends and thinner in the middle. The flexible short section has a mud channel and a flexible short section through hole with both ends through it is provided on the side wall of the shell. Slip rings are provided at both ends of the flexible short section through hole.

3. The near-bit guidance system according to claim 1 or 2, characterized in that, The guide section includes: A pusher collar connected to the drill bit, the pusher collar having a mud channel; The ribs are provided on the side wall of the push-off drill collar; A directional drill collar connected to the push drill collar; A pressure-resistant cylinder is disposed inside the directional drill collar, and a mud channel is formed between the pressure-resistant cylinder and the directional drill collar; The disc valve assembly disposed between the pressure-resistant cylinder and the push-back drill collar is used to control the extension and retraction state of the wing rib by controlling the on / off state of the mud channels at both ends. An information acquisition and control module, located inside the pressure-resistant cylinder, is used to acquire attitude information during drilling in real time and to achieve directional control of the ribs by controlling the disc valve assembly.

4. The near-bit guidance system according to claim 3, characterized in that, The disc valve assembly includes: The rib motor installed inside the pressure-resistant cylinder rotates with the pressure-resistant cylinder; The connecting shaft connected to the wing rib motor; A stationary disc valve fixed on the connecting shaft has a first mud hole at its edge; The rotating disc valve that rotates with the drill collar has multiple second mud holes at its end, which are used to control the opening and closing of the disc valve assembly when rotating relative to the stationary disc valve. The diverter is connected to the moving disc valve and the push drill collar respectively, and is used to divert the mud flowing through the moving disc valve to the rib mud channel on the side wall of the push drill collar.

5. The near-bit guidance system according to claim 3, characterized in that, The ribs are evenly distributed along the circumferential direction of the side wall of the pusher drill collar, and each rib is provided with a corresponding rib mud hole. The rib mud hole is connected to the rib mud channel on the side wall of the pusher drill collar. The pressure-resistant cylinder is fixed to the center of the directional drill collar by an upper stabilizer and a lower stabilizer. The upper stabilizer is provided with a wire hole, and the side wall of the pressure-resistant cylinder is provided with a wire hole that communicates with the wire hole of the upper stabilizer.

6. The near-bit guidance system according to claim 3, characterized in that, The information acquisition and control module also includes: Circuit skeleton; An attitude sensor mounted on the circuit frame includes an accelerometer, a rotating gyroscope, and a fluxgate. An attitude acquisition circuit mounted on the circuit frame is connected to the attitude sensor and is used to acquire and store the real-time attitude information.

7. The near-bit guidance system according to claim 1 or 2, characterized in that, The measurement-while-drilling sub includes: Measurement while drilling sub body with mud channel; A wire hole for the measurement while drilling sub is provided on the side wall of the measurement while drilling sub body, and slip rings are respectively provided at both ends of the wire hole for the measurement while drilling sub. The drilling measurement module, installed on the sidewall of the drilling measurement sub body, is used to receive and identify formation information request commands to feed back real-time formation information to the central control sub.

8. The near-bit guidance system according to claim 1 or 2, characterized in that, The pulse generator sub-section includes a pulse generator for transmitting uplink information and ground commands, wherein the central control sub-section includes: Central control unit short section body; A wiring hole for the central control section is provided on the side wall of the central control section body, and a slip ring is provided in the wiring hole for the central control section. The electronic warehouse also includes: The rectifier circuit connected to the output terminal of the pulse generator is used to rectify the electrical energy of the pulse generator and transmit it to the bus, and to detect the speed change of the pulse generator caused by the change in mud flow rate, and generate a flow rate change characteristic signal. A decoding circuit is used to identify the flow change characteristic signal and obtain the ground command.

9. The near-bit guidance system according to claim 7, characterized in that, The measurement-while-drilling module is one of the following: a gamma-ray azimuth instrument, a resistivity instrument, or an acoustic instrument.

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