Large-size resistivity non-magnetic drill collar of logging-while-drilling instrument

Abstract

The large-size resistivity non-magnetic drill collar comprises a drill collar body, a resistivity core and a radio frequency antenna, the resistivity core is arranged in a water hole of the drill collar body, and a signal transmitting part and a signal receiving part are arranged on the resistivity core; the connection nodes on the resistivity core are respectively connected with the signal transmitting part and the signal receiving part; a transmitting antenna, two receiving antennas, a first tuning circuit and a second tuning circuit are arranged in the drill collar body, the radio frequency antenna is connected with the transmitting antenna through the first tuning circuit, the transmitting antenna is connected with the two receiving antennas, and the two receiving antennas are connected with the connecting node through the second tuning circuit and the radio frequency antenna; and different signal transmission distances exist between the two receiving antennas and the transmitting antenna. The resistivity core is located in the water hole of the drill collar body, and the antennas and the circuits are located in the drill collar body, so that the maintenance cost of an instrument while drilling and the maintenance difficulty of the antennas and the circuits can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of logging-while-drilling (LWD) instruments. Further, it relates to a large-size resistivity non-magnetic drill collar for LWD instruments, and particularly to a large-size resistivity non-magnetic drill collar for a 9.5" resistivity LWD instrument. Background Art

[0002] The LWD system is a type of petroleum engineering service instrument that has developed rapidly and gradually matured in recent years. Currently, LWD instruments (such as GW-LWD) have been industrially promoted and applied. However, classified by the outer diameter of the instrument body, they can be divided into three sizes: 4.75" (inch), 6.75" (inch), and 8.25" (inch), which are respectively suitable for LWD in different-sized wellbores. Among them, the 8.25" drill collar is most suitable for operating in a 12.25" wellbore. If the 8.25" drill collar is set for construction in a 17.5" wellbore, the bottom hole assembly will generate high-frequency radial vibrations, and stress concentration and release will occur on the surface of the non-magnetic drill collar, causing fatigue in the metal interior. Long-term fatigue will cause microcracks to form and gradually expand in the metal, thus easily leading to damage to the non-magnetic drill collar. In addition, since there are antenna grooves on the 8.25" drill collar antenna, and the opening of the antenna grooves is small, it is not conducive to stress dispersion, resulting in a large force per unit area at the position corresponding to the antenna grooves, thereby increasing the fatigue degree at the position corresponding to the antenna grooves and also accelerating the propagation speed of microcracks. When the microcracks expand to a certain extent, the non-magnetic drill collar will break, causing downhole engineering accidents. From the above content, it can be seen that due to the setting of the antenna structure in the existing non-magnetic drill collar, there are significant safety risks during its operation, and at the same time, it will also greatly shorten the service life of the resistivity non-magnetic drill collar, restricting the application range and promotion effect of LWD instruments.

[0003] Therefore, based on the experience and practice of being engaged in the relevant industry for many years, the inventor of the present invention proposes a large-size resistivity non-magnetic drill collar for LWD instruments to overcome the defects of the prior art. Summary of the Invention

[0004] The purpose of the present invention is to provide a large-size resistivity non-magnetic drill collar for LWD instruments. By optimizing the structural design of the large-size resistivity non-magnetic drill collar for LWD instruments, the problem of easy breakage of the drill collar body is solved, and the occurrence of safety accidents during downhole operations is avoided. The large-size resistivity non-magnetic drill collar for LWD instruments of the present invention has the advantages of high mechanical strength, strong shock resistance, long service life, and can be used for non-destructive testing, effectively improving the operation ability of LWD instruments, and being able to reduce the maintenance cost of LWD instruments and the maintenance difficulty of antennas.

[0005] The purpose of the present invention can be achieved by the following solutions:

[0006] The present invention provides a large-size resistivity non-magnetic drill collar for a logging-while-drilling instrument, and the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument includes:

[0007] A drill collar body, which is columnar with openings at both ends, and a water eye communicating with both ends of the drill collar body is formed along its axial direction inside the drill collar body;

[0008] A resistivity core, which is arranged inside the water eye. A signal transmitting part and a signal receiving part are arranged on the resistivity core, and a connection node is provided on the resistivity core, and the connection node is respectively connected to the signal transmitting part and the signal receiving part;

[0009] A radio frequency antenna;

[0010] At least one transmitting antenna, two receiving antennas, a first tuning circuit and a second tuning circuit are arranged inside the drill collar body. The radio frequency antenna is connected to the transmitting antenna through the first tuning circuit, the transmitting antenna is respectively connected to the two receiving antennas, and the two receiving antennas are respectively connected to the connection node through the second tuning circuit and the radio frequency antenna;

[0011] There are different signal transmission distances between the two receiving antennas and the transmitting antenna, so that there are phase differences and amplitude differences between the signals received by the two receiving antennas from the transmitting antenna.

[0012] In a preferred embodiment of the present invention, a slip ring groove is provided on the end face of the drill collar body, a communication slip ring is arranged in the slip ring groove, a communication wire is arranged inside the drill collar body, and the communication slip ring is connected to the resistivity core through the communication wire.

[0013] In a preferred embodiment of the present invention, a plurality of signal enhancement parts are arranged on the outer wall of the drill collar body. The signal enhancement parts include a plurality of ferrite cores arranged at intervals along the circumferential direction of the drill collar body, and the transmitting antenna and the receiving antenna are respectively wound on the outer surfaces of the corresponding signal enhancement parts.

[0014] In a preferred embodiment of the present invention, an antenna groove is arranged along the circumferential direction on the outer wall of the drill collar body, an annular fixing seat is arranged in the antenna groove, and a plurality of fixing grooves are provided along the circumferential direction of the fixing seat, and the plurality of ferrite cores are respectively arranged in the corresponding fixing grooves;

[0015] The ferrite core is strip-shaped, the ferrite core extends along the axial direction of the drill collar body, and the length direction of the ferrite core is perpendicular to the projection of the transmitting antenna or the receiving antenna on the fixing seat.

[0016] In a preferred embodiment of the present invention, an annular radome is provided on the outer periphery of the fixed seat. The radome is connected to the outer wall of the drill collar body, and the radome houses the transmitting antenna or the receiving antenna between the radome and the corresponding fixed seat.

[0017] A plurality of slits are provided on the radome, and the plurality of slits are circumferentially opposite to the plurality of ferrite positions on the radome.

[0018] In a preferred embodiment of the present invention, a sealing body is filled in the slits and between the connection position of the radome and the outer wall of the drill collar body.

[0019] In a preferred embodiment of the present invention, the sealing body is epoxy resin glue.

[0020] In a preferred embodiment of the present invention, the antenna groove is a ring structure that is movably sleeved on the drill collar body, so that the drill collar body and the antenna groove are flexibly connected.

[0021] In a preferred embodiment of the present invention, the first tuning circuit or the second tuning circuit is respectively arranged on the corresponding tuning circuit board. A plurality of accommodation grooves are provided on the drill collar body, and the plurality of tuning circuit boards are respectively located in the corresponding accommodation grooves. A first cover plate is provided at the opening of the accommodation groove, and the first cover plate is connected to the drill collar body by first cover plate screws.

[0022] In a preferred embodiment of the present invention, a first sealing ring is provided between the first cover plate and the edge of the opening of the accommodation groove.

[0023] In a preferred embodiment of the present invention, a conductive adhesive layer is provided between the surface of the tuning circuit board facing away from the opening of the accommodation groove and the inner wall of the accommodation groove to fix the tuning circuit board in the accommodation groove.

[0024] And / or, a silica gel layer is provided on the surface of the tuning circuit board facing the opening of the accommodation groove to fix the first tuning circuit or the second tuning circuit located on the tuning circuit board.

[0025] In a preferred embodiment of the present invention, a plurality of stepped holes communicating with the water eye are provided on the drill collar body. A connecting piece is arranged in the stepped holes, at least part of the connecting piece extends into the water eye and is connected to the connection node of the resistivity core, and the RF antenna passes through the stepped holes.

[0026] In a preferred embodiment of the present invention, the connecting member is a hollow tubular structure. There are bosses on the outer wall of the connecting member, and the bosses abut against the first step in the stepped hole to limit the connecting member in the stepped hole. A second cover plate is arranged between the inner wall of the drill collar body and the outer wall of the resistivity core. At least a part of the connecting member passes through the second cover plate and is connected to the connection node of the resistivity core.

[0027] In a preferred embodiment of the present invention, a third cover plate and a circlip are arranged at one end of the stepped hole far from the nozzle, and a second sealing ring is clamped between the third cover plate and the circlip.

[0028] In a preferred embodiment of the present invention, the third cover plate and the circlip are arranged in the stepped hole in sequence from near the nozzle to far from the nozzle;

[0029] The edge of the third cover plate abuts against the second step of the stepped hole, and a clamping groove is arranged on the inner wall of the stepped hole. The edge of the circlip is embedded in the clamping groove.

[0030] In a preferred embodiment of the present invention, female threads are respectively formed at positions on the drill collar body near both ends, and the outer diameter of the female threads is smaller than the outer diameter of the drill collar body between the two female threads.

[0031] In a preferred embodiment of the present invention, an annular recess is formed on the inner wall of the female threads along its circumferential direction.

[0032] As described above, the characteristics and advantages of the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention are:

[0033] A signal transmitting part and a signal receiving part are arranged on the resistivity core, and connection nodes are provided on the resistivity core. The connection nodes are respectively connected to the signal transmitting part and the signal receiving part. At least one transmitting antenna, two receiving antennas, a first tuning circuit and a second tuning circuit are arranged in the drill collar body. The RF antenna is connected to the transmitting antenna through the first tuning circuit. The transmitting antenna is respectively connected to the two receiving antennas. The two receiving antennas are respectively connected to the connection nodes through the second tuning circuit and the RF antenna. The signal transmitting part on the resistivity core can emit a sine voltage signal, and the sine voltage signal is transmitted to the first tuning circuit through the connection node and the RF antenna in sequence. The first tuning circuit modulates the sine voltage signal and emits an electromagnetic wave signal through the transmitting antenna. The two receiving antennas respectively receive the electromagnetic wave signal. Since there are different signal transmission distances between the two receiving antennas and the transmitting antenna, there are phase differences and amplitude differences between the electromagnetic wave signals emitted by the transmitting antenna received by the two receiving antennas. The two receiving antennas then transmit the received electromagnetic wave signals to the second tuning circuit. The second tuning circuit then demodulates the electromagnetic wave signal into a voltage signal and transmits it to the connection node on the resistivity core through the RF antenna, and is transmitted by the connection node on the resistivity core to the signal receiving part on the resistivity core, so as to obtain the phase difference and amplitude difference between the electromagnetic wave signals received by the two receiving antennas. The phase difference and amplitude difference can be used as a resistance compensation value, and the true value of the formation resistivity can be inverted through the resistance compensation value to quantitatively describe the characteristics of the formation.

[0034] In addition, since the resistivity core in the present invention is located in the water hole of the drill collar body, and signal transmission components such as the RF antenna, the transmitting antenna, the receiving antenna, the first tuning circuit and the second tuning circuit are all located in the drill collar body, there is no risk of external leakage, so non-destructive flaw detection can be realized. The drill collar body will not be subjected to excessive stress at local positions due to structures such as antenna grooves, reducing the probability of the appearance of local micro-cracks and the propagation speed after the appearance of micro-cracks, which can reduce the maintenance cost of the logging-while-drilling instrument and the maintenance difficulty of the antenna and the circuit, and avoid the occurrence of safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following drawings are only intended to illustrate and explain the present invention and do not limit the scope of the present invention.

[0036] Wherein:

[0037] Figure 1 : is a schematic structural diagram of the drill collar body in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0038] Figure 2 : is a schematic cross-sectional view of the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0039] Figure 3 : Schematic diagram of the resistivity core in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0040] Figure 4 : Cross-sectional view of the end position of the drill collar body in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0041] Figure 5 : One of the schematic diagrams of the signal enhancement part in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0042] Figure 6 : Another schematic diagram of the signal enhancement part in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0043] Figure 7 : Schematic diagram of the antenna groove in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0044] Figure 8 : Schematic diagram of the antenna cover in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0045] Figure 9 : Schematic diagram of the accommodation groove in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0046] Figure 10 : Schematic diagram of the first cover plate in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0047] Figure 11 : Cross-sectional view of the connection position between the drill collar body and the resistivity core in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0048] Figure 12 : Is Figure 11 Partial enlarged view in

[0049] Figure 13 : Cross-sectional view of the female thread position in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0050] Figure 14 : One of the schematic diagrams of the electromagnetic wave signal transmission in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0051] Figure 15 : Schematic diagram of the principle for obtaining the resistivity compensation value in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0052] Figure 16 : Another schematic diagram of the electromagnetic wave signal transmission in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention.

[0053] The reference numerals in the present invention are as follows:

[0054] 1. Drill collar body; 101. Water eye

[0055] 102. Female thread; 1021. Recess

[0056] 103. Antenna groove; 104. Accommodating groove

[0057] 105. Step hole; 1051. First step

[0058] 1052. Second step; 106. Internal thread

[0059] 2. Resistivity core; 3. Radio frequency antenna

[0060] 301. First radio frequency antenna; 302. Second radio frequency antenna

[0061] 303. Third radio frequency antenna; 304. Fourth radio frequency antenna

[0062] 305. Fifth radio frequency antenna; 306. Sixth radio frequency antenna

[0063] 4. Communication slip ring; 5. Communication wire

[0064] 6. Transmitting antenna; 601. First transmitting antenna

[0065] 602. Second transmitting antenna; 603. Third transmitting antenna

[0066] 604. Fourth transmitting antenna; 7. Tuning circuit board

[0067] 701. First tuning circuit board; 702. Second tuning circuit board

[0068] 703. Third tuning circuit board; 704. Fourth tuning circuit board

[0069] 705. Fifth tuning circuit board; 801. First receiving antenna

[0070] 802. Second receiving antenna; 9. Signal enhancement part

[0071] 901. Ferrite; 10. Fixed seat

[0072] 11. Antenna cover; 1101. Gap

[0073] 12. First cover plate; 13. Cover plate screw

[0074] 14. First sealing ring; 15. Connector

[0075] 1501, boss; 16, connection node;

[0076] 1601, first connection node; 1602, second connection node;

[0077] 17, second cover plate; 18, third cover plate;

[0078] 19, snap ring; 20, second sealing ring;

[0079] 21, signal transmitting part; 2101, lower transmitter;

[0080] 2102, upper transmitter; 22, signal receiving part. Detailed implementation mode

[0081] For a clearer understanding of the technical features, objectives and effects of the present invention, the specific implementation mode of the present invention will now be described with reference to the accompanying drawings.

[0082] As Figures 1 to 16 shown, the present invention provides a large-size resistivity non-magnetic drill collar for a logging-while-drilling instrument. The large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument includes: a drill collar body 1, the drill collar body 1 is a columnar body with open ends at both ends, and a water eye 101 communicating with both ends of the drill collar body 1 is formed along its axial direction inside the drill collar body 1; a resistivity core 2, the resistivity core 2 is fixedly arranged inside the water eye 101, a signal transmitting part 21 and a signal receiving part 22 are arranged on the resistivity core 2, and a connection node (POD) 16 is provided on the resistivity core 2, and the connection node 16 is respectively connected to the signal transmitting part 21 and the signal receiving part 22; a radio frequency antenna 3, the radio frequency antenna 3 is used to connect the drill collar body 1 and the connection node 16 on the resistivity core 2, and the radio frequency antenna 3 is a communication line between the drill collar body 1 and the resistivity core 2; at least one transmitting antenna 6, two receiving antennas, a first tuning circuit and a second tuning circuit are arranged inside the drill collar body 1, the radio frequency antenna 3 is connected to the transmitting antenna 6 through the first tuning circuit, the transmitting antenna 6 is respectively connected to the two receiving antennas, and the two receiving antennas are respectively connected to the connection node 16 through the second tuning circuit and the radio frequency antenna 3; different signal transmission distances exist between the two receiving antennas and the transmitting antenna 6, so that there are phase differences and amplitude differences between the signals received by the two receiving antennas from the transmitting antenna 6, and the phase differences and amplitude differences are used as resistivity compensation values to quantitatively display formation characteristics.

[0083] In the present invention, a signal transmitting part 21 and a signal receiving part 22 are provided on the resistivity core 2, and a connection node 16 is provided on the resistivity core 2. The connection node 16 is respectively connected to the signal transmitting part 21 and the signal receiving part 22. At least one transmitting antenna 6, two receiving antennas, a first tuning circuit and a second tuning circuit are provided in the drill collar body 1. The RF antenna 3 is connected to the transmitting antenna 6 through the first tuning circuit. The transmitting antenna 6 is respectively connected to the two receiving antennas. The two receiving antennas are respectively connected to the connection node 16 through the second tuning circuit and the RF antenna 3. The signal transmitting part 21 on the resistivity core 2 can emit a sinusoidal voltage signal, and the sinusoidal voltage signal is transmitted to the first tuning circuit through the connection node 16 and the RF antenna 3 in sequence. The first tuning circuit modulates the sinusoidal voltage signal and emits an electromagnetic wave signal through the transmitting antenna 6. The two receiving antennas respectively receive the electromagnetic wave signal. Since there are different signal transmission distances between the two receiving antennas and the transmitting antenna 6, there are phase differences and amplitude differences between the electromagnetic wave signals emitted by the transmitting antenna 6 received by the two receiving antennas. The two receiving antennas then transmit the received electromagnetic wave signals to the second tuning circuit. The second tuning circuit demodulates the electromagnetic wave signals into voltage signals and transmits them to the connection node 16 on the resistivity core 2 through the RF antenna 3, and is transmitted by the connection node 16 on the resistivity core 2 to the signal receiving part 22 on the resistivity core 2, so as to obtain the phase difference and amplitude difference between the electromagnetic wave signals received by the two receiving antennas. The phase difference and amplitude difference can be used as a resistance compensation value, and the true value of the formation resistivity can be inverted through the resistance compensation value to quantitatively describe the characteristics of the formation.

[0084] Since the resistivity core 2 in the present invention is located in the water hole 101 of the drill collar body 1, and signal transmission components such as the RF antenna 3, the transmitting antenna 6, the receiving antenna, the first tuning circuit and the second tuning circuit are all located in the drill collar body 1, there is no risk of external leakage, so non-destructive flaw detection can be realized. The drill collar body 1 will not be subjected to excessive stress at local positions due to structures such as antenna grooves, reducing the probability of the appearance of local microcracks and the propagation speed after the appearance of microcracks, and can reduce the maintenance cost of the logging-while-drilling instrument and the maintenance difficulty of the antenna and the circuit, and avoid the occurrence of safety accidents.

[0085] In the present invention, female threads 102 are respectively formed on the drill collar body 1 near both ends, and the outer diameter of the female threads 102 is smaller than the outer diameter of the drill collar body 1 between the two female threads 102. Among them, the outer diameter of the drill collar body 1 between the two female threads 102 is 9.5” (inches), while the outer diameter of the female threads 102 near both ends on the drill collar body 1 is 8.25” (inches). The drill collar body 1 is thickened, which not only improves the mechanical strength and seismic resistance of the drill collar body 1, but also the drill collar body 1 of this size has a longer service life and fewer cracks during construction in a 17.5” (inch) wellbore compared to an 8.25” (inch) drill collar, avoiding potential safety hazards caused by the construction of an 8.25” (inch) drill collar in a 17.5” (inch) wellbore.

[0086] In the present invention, the resistivity core 2 has a rod-shaped structure. The signal transmitting part 21 on the resistivity core 2 can be a transmitter, and the number of transmitters can be two, namely the upper transmitter 2102 located at the upper part of the resistivity core 2 and the lower transmitter 2101 located at the lower part of the resistivity core 2; the signal receiving part 22 can be a receiver, and the receiver is located in the middle of the resistivity core 2, between the upper transmitter 2102 and the lower transmitter 2101. Among them, the resistivity core 2 and the drill collar body 1 are two independent components, independently designed, and connected and assembled before logging. In an alternative embodiment of the present invention, the number of transmitting antennas 6 can be multiple, such as 4 transmitting antennas 6. The 4 transmitting antennas 6 can alternately emit electromagnetic wave signals of 2 MHz and 500 KHz in sequence. The 2 receiving antennas simultaneously receive the electromagnetic wave signals emitted by each transmitting antenna 6, and transmit the received signals to the resistivity core 2 through the radio frequency antenna 3 for further processing.

[0087] In an alternative embodiment of the present invention, as Figure 1 、 Figure 4 shown, an annular slip ring groove is provided along the circumferential direction on the end face of the drill collar body 1 (or the end of the female thread 102), and a communication slip ring 4 is arranged in the slip ring groove. A communication wire 5 is buried inside the drill collar body 1, and the communication slip ring 4 is connected to the resistivity core 2 through the communication wire 5. The communication slip ring 4 and the communication wire 5 can supply power to the electrical components on the drill collar body 1 and the resistivity core 2, and can also be used to transmit signals. For example, the resistance compensation value can be transmitted to the upper computer on the ground through the communication slip ring 4 and the communication wire 5, and the resistance compensation value can be inverted into the true value of the formation resistivity by the software program preset in the upper computer to quantitatively describe the characteristics of the formation. Among them, the preset software program, the model for inverting the resistance compensation value, the resistivity conversion template, etc. can all be implemented by existing GW-LWD related software programs. In the present invention, it is only necessary to obtain the phase difference and amplitude difference between the electromagnetic wave signals received by the two receiving antennas (that is, obtain the resistance compensation value).

[0088] Specifically, as Figures 1 to 3 shown, the number of RF antennas 3 is six, namely the first RF antenna 301, the second RF antenna 302, the third RF antenna 303, the fourth RF antenna 304, the fifth RF antenna 305, and the sixth RF antenna 306; the number of transmitting antennas 6 is four, namely the first transmitting antenna 601, the second transmitting antenna 602, the third transmitting antenna 603, and the fourth transmitting antenna 604; the number of receiving antennas is two, namely the first receiving antenna 801 and the second receiving antenna 802. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool further includes a first tuning circuit board 701, a second tuning circuit board 702, a third tuning circuit board 703, a fourth tuning circuit board 704, and a fifth tuning circuit board 705. A first tuning circuit is respectively provided on the first tuning circuit board 701, the second tuning circuit board 702, the third tuning circuit board 703, and the fourth tuning circuit board 704, and a second tuning circuit is provided on the fifth tuning circuit board 705. The first RF antenna 301 is connected to the first transmitting antenna 601 through the first tuning circuit on the first tuning circuit board 701, the second RF antenna 302 is connected to the second transmitting antenna 602 through the first tuning circuit on the second tuning circuit board 702, the third RF antenna 303 is connected to the first receiving antenna 801 through the second tuning circuit on the fifth tuning circuit board 705, the fourth RF antenna 304 is connected to the second receiving antenna 802 through the second tuning circuit on the fifth tuning circuit board 705, the fifth RF antenna 305 is connected to the third transmitting antenna 603 through the first tuning circuit on the third tuning circuit board 703, and the sixth RF antenna 306 is connected to the fourth transmitting antenna 604 through the first tuning circuit on the fourth tuning circuit board 704.

[0089] To enhance the intensity of the electromagnetic wave signal, in an optional embodiment of the present invention, as Figure 5 , Figure 6 shown, a plurality of signal enhancement parts 9 are provided on the outer wall of the drill collar body 1. The signal enhancement parts 9 include a plurality of ferrite cores 901 arranged at intervals along the circumferential direction of the drill collar body 1, and the transmitting antenna 6 and the receiving antenna are respectively wound around the outer surface of the corresponding signal enhancement part 9. Among them, the first transmitting antenna 601 and the fourth transmitting antenna 604 are the farthest from the receiving antenna, and 25 ferrite cores 901 can be correspondingly provided but are not limited to this. The second transmitting antenna 602 and the third transmitting antenna 603 are closer to the receiving antenna, and 17 ferrite cores 901 can be correspondingly provided but are not limited to this. In the present invention, the specific number of the ferrite cores 901 is not limited, as long as the stable and accurate reception and transmission of the electromagnetic wave signal can be ensured.

[0090] Specifically, as Figures 5 to 7As shown, a circular antenna groove 103 is provided along the circumferential direction on the outer wall of the drill collar body 1. An annular fixing base 10 is arranged in the antenna groove 103. The fixing base 10 has a plurality of fixing grooves along its circumferential direction. A plurality of ferrite cores 901 are respectively arranged in the corresponding fixing grooves. The ferrite core 901 is strip-shaped, extends along the axial direction of the drill collar body 1, and the length direction of the ferrite core 901 is perpendicular to the projection of the transmitting antenna or the receiving antenna on the fixing base 10.

[0091] Further, as Figure 8 shown, an annular antenna cover 11 (the antenna cover 11 can be formed by splicing multiple pieces into a ring) is arranged on the outer circumference of the fixing base 10. The antenna cover 11 is fixedly connected to the outer wall of the drill collar body 1 through a plurality of screws. The antenna cover 11 covers the transmitting antenna 6 or the receiving antenna between the antenna cover 11 and the corresponding fixing base 10, playing a protective role for the transmitting antenna 6 or the receiving antenna.

[0092] Further, as Figure 8 shown, a plurality of slits 1101 are arranged on the antenna cover 11. The plurality of slits 1101 correspond one-to-one to the plurality of ferrite cores 901 located inside the antenna cover 11, and the plurality of slits 1101 are opposite to the plurality of ferrite cores 901 in the circumferential direction of the antenna cover 11, avoiding the influence on the intensity of the electromagnetic wave signal due to the setting of the antenna cover 11. Among them, a sealing body can be filled in the slits 1101 and between the connection position of the antenna cover 11 and the outer wall of the drill collar body 1 to prevent mud from entering the antenna cover 11 and play a sealing role.

[0093] Further, the sealing body can be, but is not limited to, epoxy resin glue.

[0094] Further, the antenna groove 103 is a circular structure that can be movably sleeved on the drill collar body 1, so that the drill collar body 1 and the antenna groove 103 are flexibly connected. Effectively disperse the stress received at the position of the antenna groove 103 when the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument bends, reduce the stress per unit area, and prevent the position of the antenna groove 103 from being damaged due to fatigue when encountering radial high-frequency vibration underground. Among them, the inner diameter of the antenna groove 103 can be, but is not limited to, 131.8 mm.

[0095] In an alternative embodiment of the present invention, the first tuning circuit or the second tuning circuit is respectively arranged on the corresponding tuning circuit board 7. As Figure 9 、 Figure 10 shown, a plurality of accommodating grooves 104 are arranged on the drill collar body 1. A plurality of tuning circuit boards 7 are respectively located in the corresponding accommodating grooves 104. A first cover plate 12 (a square cover, adapted to the top opening of the accommodating groove 104) is arranged at the top opening of the accommodating groove 104. The first cover plate 12 is fixedly connected to the drill collar body 1 through first cover plate screws 13, so as to play a protective role for the tuning circuit board 7.

[0096] Further, as Figure 10 shown, a first sealing ring 14 is provided between the first cover plate 12 and the edge of the opening of the accommodating groove 104 to prevent mud from invading into the accommodating groove 104 and ensure that the tuning circuit board 7 is not damaged.

[0097] Further, a conductive adhesive layer is provided between the board surface of the tuning circuit board 7 on the side facing away from the opening of the accommodating groove 104 and the inner wall of the accommodating groove 104 to fix the tuning circuit board 7 in the accommodating groove 104, ensure the stable position of the tuning circuit board 7 in the accommodating groove 104, and connect the ground wire on the tuning circuit board 7 to the drill collar body 1; a silica gel layer is provided on the board surface of the tuning circuit board 7 facing the opening of the accommodating groove 104 to fix the first tuning circuit or the second tuning circuit located on the tuning circuit board 7 and further reinforce the tuning circuit board 7 in the accommodating groove 104.

[0098] In an alternative embodiment of the present invention, as Figure 11 、 Figure 12 shown, a plurality of stepped holes 105 communicating with the water eye 101 are provided on the drill collar body 1, a connecting member 15 is provided in the stepped holes 105, the stepped holes 105 are stepped in diameter from the outside to the direction close to the water eye 101, at least part of the connecting member 15 extends into the water eye 101 and is connected to the connection node 16 of the resistivity core 2, and the RF antenna 3 passes through the stepped holes 105, thereby providing a laying channel for the setting of the RF antenna 3 and realizing the connection and fixation of the drill collar body 1 and the resistivity core 2.

[0099] Specifically, as Figure 11 、 Figure 12 shown, the connecting member 15 is a hollow tubular structure, an annular boss 1501 is provided on the outer wall of the connecting member 15 along its circumferential direction, the boss 1501 abuts against the first step 1051 in the stepped hole 105 to limit the connecting member 15 in the stepped hole 105 and prevent the connecting member 15 from falling off, a second cover plate 17 is provided between the inner wall of the drill collar body 1 and the outer wall of the resistivity core 2, and at least part of the connecting member 15 passes through the through hole on the second cover plate 17 and is connected to the connection node 16 of the resistivity core 2. Among them, the connecting member 15 can be but is not limited to a hollow bolt.

[0100] Further, as Figure 12 shown, a third cover plate 18 and a circlip 19 are provided at one end of the stepped hole 105 far from the water eye 101, and a second sealing ring 20 is clamped between the third cover plate 18 and the circlip 19 to prevent mud from entering the stepped hole 105.

[0101] Specifically, the third cover plate 18 and the snap ring 19 are sequentially arranged in the stepped hole 105 from the direction close to the water eye 101 to the direction away from the water eye 101; the edge of the third cover plate 18 abuts against the second step 1052 of the stepped hole 105, and a clamping groove is arranged on the inner wall of the stepped hole 105, and the edge of the snap ring 19 is embedded in the clamping groove to ensure the stable installation of the third cover plate 18 and the snap ring 19 and prevent them from falling out of the stepped hole 105.

[0102] In an alternative embodiment of the present invention, as Figure 13 shown, a ring-shaped recess 1021 is formed on the inner wall of the female thread 102 along its circumferential direction. The diameter of the recess 1021 is larger than the diameter of the water eye 101. Therefore, it can release the stress concentrated at the position of the female thread 102 when the drill collar body 1 bends, and avoid damage to the drill collar body 1 caused by excessive concentration.

[0103] Furthermore, as Figure 13 shown, an internal thread 106 is arranged on the inner wall of the female thread 102, which is convenient for the drill collar body 1 to be connected with the upper and lower drill tools.

[0104] The specific working principle of the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention is as follows:

[0105] When the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument works underground, after being powered on, the communication slip ring 4 and the communication wire 5 supply power to each electrical component on the drill collar body 1 and the resistivity core 2, and at the same time can provide signal transmission. Among them, as Figure 13 、 Figure 14 shown, the lower transmitter 2101 on the resistivity core 2 emits a sinusoidal voltage signal, which is sent to the fourth tuning circuit board 704 through the first connection node 1601 and the third radio frequency antenna 303. The fourth tuning circuit board 704 modulates the sinusoidal voltage signal into an electromagnetic wave signal and emits an electromagnetic wave signal of 2 MHz through the fourth transmitting antenna 604. The second receiving antenna 802 and the first receiving antenna 801 respectively receive the electromagnetic wave signal. The received electromagnetic wave signal passes through the fifth tuning circuit board 705, demodulates the 2 MHz electromagnetic wave signal into a voltage signal, and transmits it to the first connection node 1601 of the resistivity core 2 through the corresponding third radio frequency antenna 303 and the fourth radio frequency antenna 304, and then transmits the voltage signal to the receiver. Since the amplitude of the electromagnetic wave signal will decay with the extension of time and the phase will change periodically with the extension of time, and since the second receiving antenna 802 is closer to the fourth transmitting antenna 604 than the first receiving antenna 801, the second receiving antenna 802 receives the electromagnetic wave signal first, and the first receiving antenna 801 receives the electromagnetic wave signal later. The receiver can obtain the phase difference (i.e., phase difference) H1P and the amplitude attenuation difference (i.e., amplitude difference) H1A between the electromagnetic wave signals of the second receiving antenna 802 and the first receiving antenna 801.

[0106] Meanwhile, in order to reduce measurement errors, as Figure 16 shown, a sine voltage signal is sent by the upper transmitter 2102. The sine voltage signal is transmitted through the second connection node 1602, the first RF antenna 301, and modulated into an electromagnetic wave signal by the first tuning circuit board 701, and then an electromagnetic wave signal of 2 MHz is sent out through the first transmitting antenna 601. The first receiving antenna 801 and the second receiving antenna 802 respectively receive the electromagnetic wave signal. The electromagnetic wave signal passes through the fifth tuning circuit board 705 to demodulate the 2 MHz electromagnetic wave signal into a voltage signal, and then is transmitted to the first connection node 1601 of the resistivity core 2 through the corresponding third RF antenna 303 and fourth RF antenna 304, and then the voltage signal is transmitted to the receiver. Since the first receiving antenna 801 is closer to the first transmitting antenna 601 than the second receiving antenna 802, the first receiving antenna 801 receives the electromagnetic wave signal first, and the second receiving antenna 802 receives the electromagnetic wave signal later. The receiver can obtain the phase difference (i.e., phase difference) H2P and amplitude attenuation difference (i.e., amplitude difference) H2A between the electromagnetic wave signals of the first receiving antenna 801 and the second receiving antenna 802

[0107] Also, since the first transmitting antenna 601 and the fourth transmitting antenna 604 are symmetrically distributed with respect to the receiving antennas, that is, the distances from the first transmitting antenna 601 to the first receiving antenna 801 and the second receiving antenna 802 are approximately equal to the distances from the fourth transmitting antenna 604 to the first receiving antenna 801 and the second receiving antenna 802. Therefore, the phase differences H1P and H2P are approximately equal, and the average value H12P of the two times is taken; the amplitude differences H1A and H2A are approximately equal, and the average value H12A of the two times is taken. Due to certain errors in electronic circuit measurement, when the two transmitting antennas are symmetrically distributed with respect to the two receiving antennas, the average phase difference H12P and the average amplitude difference H12A are closer to the true values

[0108] Similarly to the above, the lower transmitter 2101 controls the third transmitting antenna 603 to transmit an electromagnetic wave signal of 2 MHz. The first receiving antenna 801 and the second receiving antenna 802 respectively receive the electromagnetic wave signal. Finally, the receiver obtains the phase difference H3P and amplitude difference H3A of the electromagnetic wave signal; the upper transmitter 2102 controls the second transmitting antenna 602 to transmit an electromagnetic wave signal of 2 MHz. The first receiving antenna 801 and the second receiving antenna 802 respectively receive the electromagnetic wave signal. Finally, the receiver obtains the phase difference H4P and amplitude difference H4A of the electromagnetic wave signal; the average phase difference H34P and the average amplitude difference H34A are obtained

[0109] Then, following the above steps, the lower transmitter 2101 and the upper transmitter 2102 respectively transmit electromagnetic wave signals of 500 KHz. The first receiving antenna 801 and the second receiving antenna 802 respectively receive the electromagnetic wave signals. Finally, the receiver obtains the average phase differences L12P and L34P, and the average amplitude differences L12A and L34A. In this way, at the end of one transmission cycle (the 4 transmitting antennas 6 sequentially transmit electromagnetic wave signals of 2 MHz and 500 KHz), 4 average phase differences H12P, H34P, L12P, L34P, and 4 average amplitude differences H12A, H34A, L12A, L34A can be obtained, which are recorded as 8 resistivity compensation values.

[0110] Finally, the receiver on the resistivity core 2 uploads the 8 resistivity compensation values to the host computer software on the ground through the first connection node 1601, the communication wire 5 (the communication wire 5 can be connected to the first connection node 1601, and the communication wire 5 can also be connected to the first connection node 1601 through the radio frequency antenna 3) and the communication slip ring 4. The host computer software inversely calculates the 8 resistivity compensation values into 8 actual formation resistivity values according to the resistivity conversion template, so as to be used to quantitatively describe the characteristics of the formation.

[0111] The characteristics and advantages of the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument of the present invention are as follows:

[0112] First, in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument, the drill collar body 1 has better mechanical strength.

[0113] Second, in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument, the antenna groove 103 adopts a flexible structure, which expands the stress release area, disperses the stress distribution, reduces the force per unit area, and improves the overall flexibility and seismic resistance of the drill collar body 1.

[0114] Third, in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument, the setting of the antenna cover 11 realizes the detachable of the antenna assembly, and the antenna groove 103 can be subjected to non-destructive flaw detection.

[0115] Fourth, in the large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument, the setting of the male thread 102 on the drill collar body 1 realizes the compatibility of the large-size resistivity non-magnetic drill collar of the 9.5” (inch) logging-while-drilling instrument with the existing 8.25” (inch) logging-while-drilling instrument, and other tools do not need to be replaced, saving costs.

[0116] V. The large-sized non-magnetic drill collar of the logging-while-drilling tool has good sealing performance, and signal transmission components such as the RF antenna 3, the transmitting antenna 6, the receiving antenna, the first tuning circuit, and the second tuning circuit are all located inside the drill collar body 1, without the risk of external leakage. Therefore, non-destructive flaw detection can be realized, and the drill collar body 1 will not be subjected to excessive stress at local positions due to structures such as antenna grooves, reducing the probability of the occurrence of local micro-cracks and the propagation speed after the appearance of micro-cracks. It can reduce the maintenance cost of the logging-while-drilling tool and the maintenance difficulty of the antenna and the circuit, and avoid the occurrence of safety accidents.

[0117] The above are only the schematic specific embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A large-size resistivity non-magnetic drill collar for a logging-while-drilling instrument, characterized in that The large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument comprises: A drill collar body, which is columnar with openings at both ends, and a water eye communicating with both ends of the drill collar body is formed axially inside the drill collar body; A resistivity core, which is arranged in the water eye. A signal transmitting part and a signal receiving part are arranged on the resistivity core, and a connection node is arranged on the resistivity core. The connection node is respectively connected with the signal transmitting part and the signal receiving part; A radio frequency antenna; At least one transmitting antenna, two receiving antennas, a first tuning circuit and a second tuning circuit are arranged inside the drill collar body. The radio frequency antenna is connected with the transmitting antenna through the first tuning circuit. The transmitting antenna is respectively connected with the two receiving antennas. The two receiving antennas are respectively connected with the connection node through the second tuning circuit and the radio frequency antenna; There are different signal transmission distances between the two receiving antennas and the transmitting antenna, so that there are phase difference and amplitude difference between the signals received by the two receiving antennas from the transmitting antenna.

2. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 1, wherein A slip ring groove is arranged on the end face of the drill collar body, and a communication slip ring is arranged in the slip ring groove. A communication wire is arranged inside the drill collar body, and the communication slip ring is connected with the resistivity core through the communication wire.

3. The large-size resistivity non-magnetic drill collar of the logging-while-drilling instrument according to claim 1, wherein A plurality of signal enhancement parts are arranged on the outer wall of the drill collar body. The signal enhancement parts include a plurality of ferrite cores arranged at intervals along the circumferential direction of the drill collar body. The transmitting antenna and the receiving antenna are respectively wound on the outer surfaces of the corresponding signal enhancement parts.

4. The large-sized non-magnetic drill collar for logging-while-drilling instrument according to claim 3, characterized in that, An antenna groove is arranged on the outer wall of the drill collar body along its circumferential direction, and an annular fixing seat is arranged in the antenna groove. A plurality of fixing grooves are arranged along the circumferential direction of the fixing seat, and the plurality of ferrite cores are respectively arranged in the corresponding fixing grooves; The ferrite core is strip-shaped, extends axially along the drill collar body, and the length direction of the ferrite core is perpendicular to the projection of the transmitting antenna or the receiving antenna on the fixing seat.

5. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 4, wherein An annular antenna cover is arranged on the outer periphery of the fixing seat. The antenna cover is connected with the outer wall of the drill collar body, and the transmitting antenna or the receiving antenna is covered between the antenna cover and the corresponding fixing seat; A plurality of gaps are arranged on the antenna cover, and the plurality of gaps are opposite to the plurality of ferrite cores in the circumferential direction of the antenna cover.

6. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 5, characterized in that, Sealing bodies are filled in the gaps and between the connection position of the antenna cover and the outer wall of the drill collar body.

7. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 6, characterized in that, The sealing body is epoxy resin glue.

8. The large-sized non-magnetic drill collar for resistivity logging-while-drilling instrument according to claim 4, characterized in that, The antenna groove is a ring structure sleeved on the drill collar body movably, so that the drill collar body and the antenna groove are flexibly connected.

9. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 1, characterized in that, The first tuning circuit or the second tuning circuit is respectively arranged on the corresponding tuning circuit board. A plurality of accommodating grooves are arranged on the drill collar body, and the plurality of tuning circuit boards are respectively located in the corresponding accommodating grooves. A first cover plate is arranged at the opening of the accommodating groove, and the first cover plate is connected with the drill collar body through first cover plate screws.

10. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 9, characterized in that, A first sealing ring is provided between the first cover plate and the edge of the opening of the accommodating groove.

11. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 9, characterized in that, A conductive adhesive layer is provided between the surface of the tuning circuit board on the side facing away from the opening of the accommodating groove and the inner wall of the accommodating groove to fix the tuning circuit board in the accommodating groove; And / or, a silica gel layer is provided on the surface of the tuning circuit board on the side facing the opening of the accommodating groove to fix the first tuning circuit or the second tuning circuit located on the tuning circuit board.

12. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 1, characterized in that, A plurality of stepped holes communicating with the water eye are provided on the drill collar body. A connecting member is provided in the stepped holes. At least a part of the connecting member extends into the water eye and is connected to the connection node of the resistivity core. The RF antenna passes through the stepped holes.

13. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 12, wherein The connecting member is a hollow tubular structure. A boss is provided on the outer wall of the connecting member. The boss abuts against the first step in the stepped hole to limit the connecting member in the stepped hole. A second cover plate is provided between the inner wall of the drill collar body and the outer wall of the resistivity core. At least a part of the connecting member passes through the second cover plate and is connected to the connection node of the resistivity core.

14. The large-sized non-magnetic drill collar with resistivity for logging-while-drilling instrument according to claim 12 or 13, characterized in that, A third cover plate and a snap ring are provided at one end of the stepped hole far from the water eye, and a second sealing ring is clamped between the third cover plate and the snap ring.

15. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 14, characterized in that, The third cover plate and the snap ring are sequentially arranged in the stepped hole from the direction close to the water eye to the direction far from the water eye; The edge of the third cover plate abuts against the second step of the stepped hole, and a clamping groove is provided on the inner wall of the stepped hole. The edge of the snap ring is embedded in the clamping groove.

16. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 1, characterized in that Female threads are respectively formed at positions on the drill collar body close to both ends. The outer diameter of the female threads is smaller than the outer diameter of the drill collar body between the two female threads.

17. The large-size resistivity non-magnetic drill collar of the logging-while-drilling tool according to claim 16, wherein An annular recess is formed along the circumferential direction on the inner wall of the female threads.

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