Near-bit gamma electromagnetic wave imaging logging instrument with remote detection emission and power generation functions

Abstract

The invention belongs to the technical field of petroleum and natural gas drilling, and discloses a near-bit gamma electromagnetic wave imaging logging instrument with far detection emission and power generation functions, which comprises a drill collar body, a water hole is arranged in the drill collar body along the axial direction, and an emission antenna, a first receiving antenna, a second receiving antenna, a first antenna port and a second antenna port are arranged on the drill collar body; a sealing fastening sleeve, a circuit framework, a lower fluid director and a mud turbine power generation device are arranged in the water hole, the circuit framework is provided with a containing cavity, the middle of the mud turbine power generation device is located in the containing cavity, the lower end of the mud turbine power generation device is connected with the lower fluid director, and an orientation gamma measuring circuit is arranged in the circuit framework. The near-bit lateral resistivity logging instrument has a certain forward probing capability and a certain azimuth electromagnetic wave measuring function, and has larger axial forward probing and radial probing edge distance compared with a near-bit lateral resistivity logging instrument. The method is suitable for oil-based mud and is also suitable for water-based mud.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas drilling, and particularly relates to a near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions. Background Art

[0002] The main functions of existing near-bit logging technologies and equipment include: near-bit azimuth gamma imaging, near-bit lateral resistivity imaging, bit resistivity, and near-bit electromagnetic wave resistivity.

[0003] Currently, existing near-bit gamma lateral resistivity imaging instruments use the current lateral measurement principle to achieve functions such as lateral resistivity measurement, bit resistivity measurement, and resistivity imaging. Their main disadvantages are that they are not suitable for oil-based mud logging environments and have a relatively shallow axial forward detection distance. Although existing near-bit gamma electromagnetic wave resistivity imaging instruments can be used in oil-based mud environments, they generally do not have azimuth electromagnetic wave detection functions, and their axial forward exploration capabilities are also relatively shallow.

[0004] Existing electromagnetic wave far-detection logging-while-drilling instruments at home and abroad, whether single-section or a combination of multiple sections, are relatively long and can only be placed above the positive displacement motor at a relatively far distance from the bit, obtaining less formation information in front of the bit and having weak axial forward exploration capabilities.

[0005] In summary, the existing resistivity logging-while-drilling technologies and equipment mainly have the following deficiencies:

[0006] (1) The near-bit lateral resistivity logging tool is not suitable for oil-based mud environments;

[0007] (2) The near-bit lateral resistivity logging tool has a relatively shallow radial edge detection and axial forward detection distance;

[0008] (3) Near-bit electromagnetic wave logging technologies and equipment generally do not have azimuth electromagnetic wave detection functions;

[0009] (4) Existing far-detection electromagnetic wave instruments, whether single-section or multiple sections, are relatively long and cannot be placed near the bit, with extremely weak axial forward exploration capabilities;

[0010] (5) Near-bit imaging logging tools measure more parameters and require greater power supply. Currently, near-bit instruments generally use battery power supply, with a short power supply time, and cannot meet the long-term (200 hours) power supply requirements of near-bit electromagnetic wave imaging logging tools through battery power supply. Summary of the Invention

[0011] In view of the above problems, the present invention provides a near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions, adopting the following technical solutions:

[0012] A near-bit gamma electromagnetic wave imaging logging tool with functions of far-detection emission and power generation, comprising a drill collar body. A water eye is axially arranged inside the drill collar body. An emission antenna is arranged outside the lower end of the drill collar body, and a first receiving antenna and a second receiving antenna are arranged outside the upper end of the drill collar body. A first antenna port is further arranged between the first receiving antenna and the second receiving antenna on the drill collar body, and a second antenna port is arranged between the second receiving antenna and the emission antenna.

[0013] A sealing and fastening sleeve, a circuit framework, a lower flow deflector and a mud turbine power generation device are arranged inside the water eye. The sealing and fastening sleeve and the lower flow deflector fix the circuit framework inside the water eye. The circuit framework has a receiving cavity. The middle part of the mud turbine power generation device is located inside the receiving cavity. The lower end of the mud turbine power generation device is connected to the lower flow deflector, and the upper end of the mud turbine power generation device penetrates through the sealing and fastening sleeve. An azimuth gamma measurement circuit is arranged inside the circuit framework.

[0014] Further, the normal directions of the first receiving antenna and the second receiving antenna are the same as the axis of the drilling direction, and the emission antenna has an angle with the axis of the drilling direction.

[0015] Further, a wear-resistant belt is further arranged between the second receiving antenna and the second antenna port.

[0016] Further, first antenna protection covers are arranged outside both the first receiving antenna and the second receiving antenna, and a second antenna protection cover is further arranged outside the emission antenna.

[0017] Further, the circuit framework includes an emission chamber, a first receiving chamber, a second receiving chamber, a main control chamber and a gamma chamber;

[0018] Among them, a main control processing circuit and sector sensors are arranged inside the main control chamber, an azimuth gamma measurement circuit is arranged inside the gamma chamber, an emission circuit is arranged inside the emission chamber, and power supply modules and receiving circuits are arranged inside both the first receiving chamber and the second receiving chamber.

[0019] Further, the main control processing circuit includes an AD acquisition circuit, a data processing circuit, a signal control circuit and a DA conversion circuit connected in sequence. Among them, the AD acquisition circuit is connected to the two receiving circuits, the data processing circuit is connected to the azimuth gamma measurement circuit, the signal control circuit is connected to other instruments through a communication driving interface, and the DA acquisition and conversion circuit is connected to the emission circuit.

[0020] Further, the emission circuit includes a power supply filtering circuit, an emission amplifying circuit and an emission tuning circuit connected in sequence;

[0021] The receiving circuit includes a filter amplification circuit and a receiving tuning circuit connected in sequence;

[0022] The azimuth gamma measurement circuit includes a sector processing circuit and an integrated gamma detector. Among them, the sector sensor is connected to the sector processing circuit, and the integrated gamma detector is connected to the sector processing circuit.

[0023] Furthermore, the power supply module is electrically connected to the mud turbine power generation device.

[0024] Furthermore, the mud turbine power generation device includes a guide wheel, an impeller, a connecting sleeve, a sealed housing, a pressure-bearing seal cylinder, a mud bearing, a transmission shaft, a magnetic coupling assembly, a sealing sleeve, and a generator;

[0025] Among them, the lower end of the sealed housing is connected to the pressure-bearing seal cylinder, the upper end of the sealed housing is in dynamic seal connection with the first end of the connecting sleeve, and the second end of the connecting sleeve is fixedly connected to the impeller; the generator is arranged in the sealed housing, the shaft of the generator is connected to the first end of the transmission shaft, and the sealing sleeve is sleeved on the shaft of the generator and the transmission shaft;

[0026] The second end of the transmission shaft penetrates through the central hole of the impeller, and the guide wheel is fixedly connected to the transmission shaft and is located between the second end of the transmission shaft and the impeller;

[0027] Between the first end of the transmission shaft and the guide wheel, a first mud bearing, a second mud bearing, and a third mud bearing are arranged. The impeller is fixedly connected to the outer ring of the first mud bearing. The magnetic coupling assembly is arranged between the second mud bearing and the third mud bearing. The connecting sleeve is fixedly connected to the outer rings of the second mud bearing and the third mud bearing. The magnetic coupling assembly is arranged in the connecting sleeve. The inner cylinder of the magnetic coupling assembly is fixedly connected to the transmission shaft, and the outer cylinder of the magnetic coupling assembly is fixedly connected to the connecting sleeve.

[0028] Furthermore, the mud turbine power generation device further includes an impact-proof cap, and the second end of the transmission shaft is threadedly and fixedly connected to the impact-proof cap.

[0029] Furthermore, the mud turbine power generation device further includes an oil balance piston. An oil cavity is axially arranged inside the transmission shaft, and the oil balance piston is slidably connected to the oil cavity.

[0030] A near-bit electromagnetic wave imaging logging method measures the formation resistivity through the near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions, and includes the following steps:

[0031] The transmitting antenna emits electromagnetic wave signals at a set angle. The electromagnetic wave signals are equivalent to an axial Z component and a radial X component orthogonal to the axial component. The first receiving antenna and the second receiving antenna receive the coaxial ZZ component and the orthogonal XZ component.

[0032] The relationship between the amplitude ratio and phase difference of the signals received by the first receiving antenna and the second receiving antenna and the formation resistivity is obtained through numerical simulation to draw a chart. The measured signals are converted into formation resistivity information according to the chart.

[0033] A near-bit electromagnetic wave imaging logging method conducts radial edge detection and axial forward detection through the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmitting and power generation functions, including the following steps:

[0034] When the transmitting antenna emits electromagnetic wave signals at a set angle, the electromagnetic wave signals are equivalent to an axial Z component and a radial X component orthogonal to the axial component, and the first receiving antenna and the second receiving antenna respectively receive the coaxial ZZ component and the orthogonal XZ component, the formation azimuth resistivity is characterized by the azimuth angle of the electromagnetic wave measurement signal to achieve radial edge detection.

[0035] When the transmitting antenna emits electromagnetic wave signals at a set angle, the electromagnetic wave signals are equivalent to an axial Z component and a radial X component orthogonal to the axial component, and the first receiving antenna and the second receiving antenna both receive the orthogonal XZ component and the coaxial ZZ component, the formation resistivity in front of the bit is measured to achieve the function of axial forward detection.

[0036] A near-bit electromagnetic wave imaging logging method conducts axial forward detection distance measurement through the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmitting and power generation functions, including the following steps:

[0037] Establish a resistivity forward detection model;

[0038] Based on the resistivity forward detection model, the response characteristic curve of the receiving antenna is calculated according to the magnetic field strength at the first receiving antenna and the second receiving antenna. By selecting the cut-off value of the difference between the geological signal of the logging tool and the uniform space response, the axial forward detection distance of the logging tool is determined.

[0039] A near-bit electromagnetic wave imaging logging method conducts far-detection transmission through the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmitting and power generation functions, including the following steps:

[0040] The near-bit gamma electromagnetic wave imaging logging tool is used as a pre-transmission module and is combined and connected with an electromagnetic wave far-detection receiving sub-section.

[0041] The beneficial effects of the present invention:

[0042] 1. The present invention uses near-bit electromagnetic waves, which have a certain forward detection ability and a greater axial forward detection and radial boundary detection distance compared to near-bit lateral resistivity logging tools.

[0043] 2. The present invention adopts the near-bit azimuth electromagnetic wave method, which is applicable to both oil-based mud and water-based mud.

[0044] 3. The present invention has the ability to measure azimuth electromagnetic waves, can collect electromagnetic wave information in different azimuths in the radial direction of the formation, and realizes the function of azimuth electromagnetic wave measurement.

[0045] 4. The present invention has a far-detection emission function. By moving the emission antenna from above the screw to near the bit, the axial forward detection ability is greatly improved. The present invention is connected to the bit below the screw and is combined with electromagnetic wave ultra-far-detection receiving short joints with different source distances as a pre-emission short section to directly measure the electromagnetic wave signal in front of the bit, with a forward detection ability improved by more than 10 meters compared to conventional electromagnetic wave far-detection instruments.

[0046] 5. The present invention is internally provided with a mud turbine power generation device, which solves the problem of insufficient battery power supply due to increased measurement parameters and power consumption in the measurement system, and meets the requirement of long-term downhole operation.

[0047] Other features and advantages of the present invention will be described in the following specification, and part of them will be obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures pointed out in the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0049] Figure 1 FIG. shows the structural schematic diagram of a near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to an embodiment of the present invention;

[0050] Figure 2 FIG. shows the external structural schematic diagram of a near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to an embodiment of the present invention;

[0051] Figure 3 FIG. shows the internal structural schematic diagram of a near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to an embodiment of the present invention;

[0052] Figure 4 Shows an exploded view of a near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to an embodiment of the present invention;

[0053] Figure 5 Shows a schematic diagram of the circuit skeleton and sensor layout according to an embodiment of the present invention;

[0054] Figure 6 Shows a schematic diagram of the circuit connection within the circuit skeleton according to an embodiment of the present invention;

[0055] Figure 7 Shows an exploded view of the external structure of a mud turbine power generation device according to an embodiment of the present invention;

[0056] Figure 8 Shows an exploded view of the internal structure of a mud turbine power generation device according to an embodiment of the present invention;

[0057] Figure 9 Shows a schematic diagram of a formation boundary distance definition model according to an embodiment of the present invention;

[0058] Figure 10 Shows a schematic diagram of formation boundary / forward detection distance definition according to an embodiment of the present invention;

[0059] Figure 11 Shows a schematic diagram of a forward detection distance definition model according to an embodiment of the present invention;

[0060] Figure 12 Shows a connection schematic diagram for far-detection emission of a near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to an embodiment of the present invention;

[0061] Figure 13 Shows a schematic diagram of an amplitude ratio resistivity chart according to an embodiment of the present invention;

[0062] Figure 14 Shows a schematic diagram of a phase difference resistivity chart according to an embodiment of the present invention;

[0063] Figure 15 Shows a schematic diagram of the axial forward detection characteristic according to an embodiment of the present invention;

[0064] Figure 16 Shows a schematic diagram of the radial formation boundary characteristic according to an embodiment of the present invention.

[0065] In the figure: 1. Drill collar body; 2. Bit; 3. Sub; 4. Positive displacement motor; 5. Transmitting antenna; 6. First receiving antenna; 7. Second receiving antenna; 8. First antenna port; 9. Second antenna port; 10. Wear band; 11. First antenna protective cover; 12. Second antenna protective cover; 13. Sealing and fastening sleeve; 14. Circuit skeleton; 15. Lower flow deflector; 16. Mud turbine power generation device; 17. Impact protection cap; 18. Guide wheel; 19. Impeller; 20. Connecting sleeve; 21. Sealing housing; 22. Pressure-bearing sealing cylinder; 23. Oil balance piston; 24. Mud bearing; 25. Transmission shaft; 26. Magnetic coupling assembly; 27. Sealing sleeve; 28. Generator; 29. Fastener. Detailed implementation manners

[0066] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0067] It should be noted that the terms "first", "second", etc. in this application are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to describe the embodiments of the present application herein. In this application, the orientation or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "radial", etc. are based on the orientation or positional relationships shown in the drawings.

[0068] The present invention provides a near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions, which has power generation and far-detection transmission functions, realizes the measurement of formation parameters such as natural gamma and resistivity, has gamma electromagnetic wave imaging functions and radial edge detection and axial forward detection functions, and can be used for complex reservoir rating and precise geological steering, meeting the requirements of accurate steering, comprehensive evaluation and efficient drilling services for complex reservoirs in highly deviated wells and horizontal wells.

[0069] As Figure 1 and Figure 2 shown, a near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions includes a drill collar body 1. The lower end of the drill collar body 1 is connected to a bit 2, and the upper end of the drill collar body 1 is connected to a sub 3. The upper end of the drill collar body 1 is connected to a positive displacement motor 4 through the sub 3. The sub 3 converts the thread type and protects the internal components.

[0070] Among them, a water hole is axially arranged inside the drill collar body 1, as Figure 2 and Figure 3 shown. An emission antenna 5 is arranged outside the lower end of the drill collar body 1, and a first receiving antenna 6 and a second receiving antenna 7 are arranged outside the upper end of the drill collar body 1; a first antenna port 8 is further arranged between the first receiving antenna 6 and the second receiving antenna 7 on the drill collar body 1, and a second antenna port 9 is arranged between the second receiving antenna 7 and the emission antenna 5.

[0071] The first receiving antenna 6 and the second receiving antenna 7 receive the electromagnetic wave signals carrying formation information and cooperate with the emission antenna 5 to measure the formation resistivity; the emission antenna 5 emits electromagnetic wave signals into the formation, cooperates with the first receiving antenna 6 and the second receiving antenna 7 to measure the formation resistivity, and can also cooperate with the far-detection receiving sub to work, emitting and receiving wireless short-distance transmission signals.

[0072] As Figure 1 shown, for example, the source distances of the first receiving antenna 6 and the second receiving antenna 7 are different, and the normal directions of the first receiving antenna 6 and the second receiving antenna 7 are the same as the axis of the drilling direction, and the emission antenna 5 has an included angle with the axis of the drilling direction.

[0073] The emission antenna 5 emits electromagnetic wave signals at an inclination angle of 45°. The electromagnetic wave signals can be equivalent to an axial Z component and a radial X component orthogonal to the axial component. The electromagnetic wave signals received by the first receiving antenna 6 and the second receiving antenna 7 are the superposition of the axial component and the radial component. When the first receiving antenna 6 and the second receiving antenna 7 receive the axial Z component, a ZZ emission-receiving antenna combination is formed with the emission antenna 5. However, relying only on receiving the electromagnetic wave signals of the axial Z component is not enough to obtain azimuth information. When the first receiving antenna 6 and the second receiving antenna 7 receive the radial XZ component, an XZ emission-receiving antenna combination is formed with the emission antenna 5. As the logging tool and the drill bit 2 rotate, the electromagnetic wave signals collected by the XZ emission-receiving antenna combination can be processed to obtain azimuth information, forming a near-bit azimuth electromagnetic wave logging technology.

[0074] In the near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions of the present invention, the emission antenna 5 is set to emit at an inclination angle of 45° and has the ability to measure azimuth electromagnetic waves. When the first receiving antenna 6 and the second receiving antenna 7 receive the XZ component, they can collect electromagnetic wave information in different azimuths in the formation radial direction and realize the azimuth electromagnetic wave measurement function.

[0075] The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions of the present invention has a far-detection electromagnetic wave emission function. Compared with the prior art, the emission antenna 5 is moved from above the screw 4 to near the bit 2, greatly improving the axial forward detection ability. For the azimuth electromagnetic wave logging tool with the existing emission antenna 5 located above the screw 4, the forward detection distance needs to subtract the distance from the emission point to the bit 2 (at least the length of one screw). To obtain a greater forward detection distance, the emission point needs to be placed as far forward as possible. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions of the present invention is placed below the screw 4 and connected to the bit 2. The front emission antenna 5 is combined with the first receiving antenna 6 and the second receiving antenna 7 with different source distances to directly measure the electromagnetic wave signals containing the formation information in front of the bit 2, improving the forward detection ability by more than 10 meters compared with the conventional electromagnetic wave far-detection instrument.

[0076] For example, as Figure 2 shown, a wear-resistant belt 10 is also provided between the second receiving antenna 7 and the second antenna port 9. As Figure 4 shown, first antenna protective covers 11 are provided outside both the first receiving antenna 6 and the second receiving antenna 7, and a second antenna protective cover 12 is also provided outside the emission antenna 5.

[0077] The first antenna protective covers 11 and the second antenna protective cover 12 protect the antennas from being damaged by external forces; the wear-resistant belt 10 protects the first antenna protective covers 11 and the second antenna protective cover 12, enhancing the wear resistance of the outer surface of the logging tool and improving the service life of the measurement sub.

[0078] As Figure 3 and Figure 4 shown, a sealing and fastening sleeve 13, a circuit skeleton 14, a lower flow deflector 15, and a mud turbine power generation device 16 are provided in the water eye inside the drill collar body 1. The sealing and fastening sleeve 13 and the lower flow deflector 15 fix the circuit skeleton 14 in the water eye. The circuit skeleton 14 has an accommodation cavity. The middle part of the mud turbine power generation device 16 is located in the accommodation cavity. The lower end of the mud turbine power generation device 16 is connected to the lower flow deflector 15. The lower flow deflector 15 is used to connect and straighten the mud generator 28, change the mud channel, and pressure-seal the circuit skeleton 14; the upper end of the mud turbine power generation device 16 penetrates through the sealing and fastening sleeve 13 and extends into the liquid flow channel of the adapter 3.

[0079] For example, as Figure 5 and Figure 6 shown, the circuit skeleton 14 includes an emission chamber, a first receiving chamber, a second receiving chamber, a main control chamber, and a gamma chamber. Among them, a main control processing circuit and sector sensors are provided in the main control chamber, an azimuth gamma measurement circuit is provided in the gamma chamber, and an emission circuit is provided in the emission chamber. The emission circuit includes a power supply filtering circuit, an emission amplification circuit, and an emission tuning circuit connected in sequence.

[0080] A power module and a receiving circuit are provided in both the first receiving bin and the second receiving bin. The receiving circuit includes a filter amplification circuit and a receiving tuning circuit connected in sequence.

[0081] The main control processing circuit includes an AD acquisition circuit, a data processing circuit, a signal control circuit, and a DA conversion circuit connected in sequence. Among them, the AD acquisition circuit is connected to the two receiving circuits, the data processing circuit is connected to the azimuth gamma measurement circuit, the signal control circuit is connected to other instruments through a communication drive interface, and the DA acquisition and conversion circuit is connected to the transmitting circuit.

[0082] The azimuth gamma measurement circuit includes a sector processing circuit and an integrated gamma detector. Among them, the sector sensor is connected to the sector processing circuit, and the integrated gamma detector is connected to the sector processing circuit.

[0083] Through the azimuth gamma measurement circuit, the present invention can receive gamma rays in the formation during rotation following the drill string. Utilizing gamma ray imaging technology, it realizes the integration of gamma and resistivity parameters, and realizes the function of reservoir boundary identification using the gamma imaging function during the logging while drilling process.

[0084] In the present invention, the near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions mainly collects formation azimuth resistivity and azimuth natural gamma information. In addition, it also has the function of collecting information such as well inclination, azimuth, vibration, temperature, and rotation speed.

[0085] Among them, the main control processing circuit is used for the control of the overall work process, signal acquisition, data processing, engineering data calculation and storage, and communication with other instruments.

[0086] The transmitting circuit is used to filter, shape, amplify, and power-amplify the transmitting signal sent out by the DA conversion of the main control processing circuit, and provide the required energy and signal for the transmitting antenna 5.

[0087] The receiving circuit is used to select the frequency of the signal from the receiving antenna through a resonant circuit, amplify and filter the signal, and then further amplify it and send it to the AD acquisition module.

[0088] The azimuth gamma measurement circuit is used to measure parameters such as well inclination azimuth, tool face, and gamma, and send the measurement signal to the main control processing circuit.

[0089] The power module is electrically connected to the mud turbine power generation device 16. The power module is used to convert and filter the electrical energy generated by the mud turbine power generation device 16, and provide various required power supplies for each circuit of the logging tool.

[0090] The mud turbine power generation device 16 is used to provide power supply for the logging tool when it works at low frequency as a far-detection front-end transmitting sub-section.

[0091] When the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions of the present invention is used as a far-detection pre-transmission short section, to meet multiple measurement requirements, the working frequency is relatively low and the power consumption is relatively large. Traditional battery power supply is not sufficient to support long-term downhole operation (200 hours). By means of the built-in mud turbine power generation device 16 located in the water hole of the drill collar body 1, the problems of high power consumption during low-frequency operation and short endurance time are solved.

[0092] The mud turbine power generation device 16 is located in the water hole of the drill collar body 1, can provide a power supply of about 70-100 w, and includes high, medium, and low turbines to match the mud displacement.

[0093] For example, as Figure 3 、 Figure 4 、 Figure 7 and Figure 8 shown, the mud turbine power generation device 16 includes an impact-proof cap 17, a guide wheel 18, an impeller 19, a connecting sleeve 20, a sealing housing 21, a pressure-bearing sealing cylinder 22, an oil balance piston 23, a mud bearing 24, a transmission shaft 25, a magnetic coupling assembly 26, a sealing sleeve 27, and a generator 28.

[0094] Among them, the lower end of the sealing housing 21 is connected to the pressure-bearing sealing cylinder 22, the upper end of the sealing housing 21 is in dynamic sealing connection with the first end of the connecting sleeve 20, and the second end of the connecting sleeve 20 is fixedly connected to the impeller 19 by threads; the generator 28 is arranged in the sealing housing 21, the shaft of the generator 28 is connected to the first end of the transmission shaft 25, and the sealing sleeve 27 is sleeved on the shaft of the generator 28 and the transmission shaft 25.

[0095] The second end of the transmission shaft 25 passes through the central hole of the impeller 19, the second end of the transmission shaft 25 is fixedly connected to the impact-proof cap 17 by threads, the guide wheel 18 is fixedly connected to the transmission shaft 25 and is located between the second end of the transmission shaft 25 and the impeller 19. For example, the transmission shaft 25 is provided with a first keyway and a threaded blind hole near the impact-proof cap 17, the guide wheel 18 is provided with a second keyway matching the keyway of the transmission shaft 25, the second keyway of the guide wheel 18 is key-connected to the first keyway of the transmission shaft 25 through a connecting key, and a fastener 29 passes through the guide wheel 18 and is connected to the threaded blind hole of the transmission shaft 25 to realize the fixation of the guide wheel 18 and the transmission shaft 25.

[0096] An oil cavity is axially arranged inside the transmission shaft 25, and the oil balance piston 23 is slidably connected to the oil cavity for pressure balance.

[0097] A first mud bearing 24, a second mud bearing 24, and a third mud bearing 24 are provided between the first end of the drive shaft 25 and the guide wheel 18. The impeller 19 is fixedly connected to the outer ring of the first mud bearing 24. The magnetic coupling assembly 26 is arranged between the second mud bearing 24 and the third mud bearing 24. The connecting sleeve 20 is fixedly connected to the outer rings of the second mud bearing 24 and the third mud bearing 24. The magnetic coupling assembly 26 is arranged inside the connecting sleeve 20. The inner cylinder of the magnetic coupling assembly 26 is fixedly connected to the drive shaft 25, and the outer cylinder of the magnetic coupling assembly 26 is fixedly connected to the connecting sleeve 20.

[0098] For example, the length of the drill collar body 1 is about 1 m, and the maximum diameter is about 180 mm, realizing highly integrated and miniaturized azimuth gamma electromagnetic wave imaging logging tool near the bit.

[0099] Based on the above-mentioned near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions, the present invention also provides a near-bit electromagnetic wave imaging logging method, including the following steps:

[0100] S1. Measuring the formation resistivity through the near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions, including the following steps:

[0101] S11. The transmitting antenna 5 emits an electromagnetic wave signal at a set angle (for example, a 45° dip angle). The electromagnetic wave signal is equivalent to an axial Z component and a radial X component orthogonal to the axial component. Both the first receiving antenna 6 and the second receiving antenna 7 receive the radial Z component. At this time, the antenna structure of the logging tool is an axial single-transmission and dual-reception antenna structure.

[0102] Among them, the transmitting antenna 5 emits a harmonic signal, and the transmitting frequencies are 2 MHz and 400 KHz. The first receiving antenna 6 and the second receiving antenna 7 receive the signal amplitude and phase. The amplitude ratio (Att) and phase difference (ΔΦ) of the signals received by the first receiving antenna 6 and the second receiving antenna 7 are defined as:

[0103]

[0104] ΔΦ = Φ1 - Φ2 (2)

[0105] In the formula, V R1 and V R2 are the electromotive forces of the first receiving antenna 6 and the second receiving antenna 7 respectively, and Φ1 and Φ2 are the phases of the induced electromotive forces of the first receiving antenna 6 and the second receiving antenna 7 respectively.

[0106] S12. Obtaining the relationship between the amplitude ratio and phase difference of the signals received by the first receiving antenna 6 and the second receiving antenna 7 and the formation resistivity through numerical simulation, and drawing a chart. Converting the measured signals into formation resistivity information according to the chart.

[0107] S2. Perform radial look-around and axial look-ahead through a near-bit gamma electromagnetic wave imaging logging tool with functions of far-detection emission and power generation, including the following steps:

[0108] S21. The transmitting antenna 5 emits an electromagnetic wave signal at a set angle (for example, a 45° dip angle). The electromagnetic wave signal is equivalent to an axial Z component and a radial X component orthogonal to the axial component. When the first receiving antenna 6 and the second receiving antenna 7 receive the radial XZ component and the axial ZZ component respectively, measure the formation azimuth resistivity according to the electromagnetic wave signal measurement angle to achieve radial look-around.

[0109] In this step, the logging tool rotates with the bit 2, and the electromagnetic wave signal measurement angle changes. The formation azimuth resistivity can be measured to achieve the radial look-around function.

[0110] S22. The transmitting antenna 5 emits an electromagnetic wave signal at a set angle (for example, a 45° dip angle). The electromagnetic wave signal is equivalent to an axial Z component and a radial X component orthogonal to the axial component. When both the first receiving antenna 6 and the second receiving antenna 7 receive the axial ZZ component and the radial XZ component, the transmitting antenna 5, the first receiving antenna 6, and the second receiving antenna 7 of the logging tool are arranged near the bit 2, and the resistivity of the formation in front of the bit 2 can be measured to achieve the axial look-ahead function.

[0111] S3. Measure the radial look-around distance and the axial look-ahead distance through a near-bit gamma electromagnetic wave imaging logging tool with functions of far-detection emission and power generation.

[0112] Among them, the axial look-ahead distance refers to the distance from the wellbore to the farthest formation interface that the logging tool can detect axially. As Figure 11 shown, when the logging tool gradually moves away from the formation interface, the geological signal is gradually less affected by the interface or the surrounding rock Rt1 and gradually approaches the response of a homogeneous formation, that is, the geological signal of a homogeneous infinite formation with a resistivity of Rt2. When the difference between the logging tool geological signal and the homogeneous space response is equal to a certain cut-off value (i.e., the minimum geological signal that the logging tool can measure) as Figure 10 shown, it can be considered that the influence of the interface or the surrounding rock is almost zero at this time, and the distance from this position to the interface is defined as the look-ahead distance of the logging tool.

[0113] The radial look-around distance refers to the distance from the wellbore to the farthest formation interface that the logging tool can detect radially. The definition of the look-around distance is based on the logging tool geological signal and a single-interface formation model as Figure 9As shown in the figure. The logging tool is located in a formation with resistivity Rt2 and parallel to the formation interface. The resistivity of the adjacent formation is Rt1. As the logging tool gradually moves away from the formation interface, the geological signal gradually decreases (i.e., the influence of the interface or the adjacent formation gradually decreases). When the geological signal decreases to the minimum geological signal that the logging tool can detect, the distance DTB from the logging tool to the interface is defined as the boundary detection distance.

[0114] The measurement principle of the radial boundary detection distance is similar to that of the axial forward detection distance. The following takes the method of defining the axial forward detection distance of the logging tool as an example for illustration. According to electromagnetic theory, the response contribution of the logging tool in a conductive formation comes from all directions in the space around the logging tool. The measurement signal of the logging tool is a function of the resistivity of the medium in the surrounding space, the interface, and the interface orientation. The proportion of the contribution of each region in the space to the total response is different. When detecting the information in front of the logging tool, the measured value simultaneously includes the contributions from all spatial directions behind and on the sides of the logging tool.

[0115] For example, step S3 includes the following steps:

[0116] S31. Establish a resistivity forward detection model, specifically as follows:

[0117] Using the principle of electromagnetic wave reflection at the formation interface, calculate the response when the logging tool reaches the boundary, so as to identify whether there is a formation boundary in front of the formation, and establish a resistivity forward detection model. Based on the rectangular coordinate system (x, y, z) as the model basis, the z direction is the axial direction of the logging tool and points to the drilling direction, the x direction is to the right on the paper, and the y direction is perpendicular to the paper and outward, as Figure 11 shown. The wellbore is perpendicular to the formation interface. The resistivity of the lower surrounding rock is Rt1, the resistivity of the overlying formation is Rt2, the length of the logging tool is L, and the distance from the front end of the logging tool to the formation boundary is DTB.

[0118] S32. Based on the resistivity forward detection model, calculate the response characteristic curve of the receiving antenna according to the magnetic field intensities at the first receiving antenna 6 and the second receiving antenna 7. By selecting the cut-off value of the difference between the geological signal of the logging tool and the response in a homogeneous space (i.e., the minimum geological signal that the logging tool can measure), determine the axial forward detection distance of the logging tool.

[0119] In this step, the axial forward detection ability of the logging tool is clarified by discussing the logging response when the logging tool is perpendicular to the formation interface. As the logging tool approaches the formation interface (DTB gradually decreases), calculate the response of the receiving antenna according to the magnetic field intensities at the first receiving antenna 6 and R2. According to the response characteristic curve of the receiving antenna, by selecting the cut-off value of the difference between the geological signal of the logging tool and the response in a homogeneous space (i.e., the minimum geological signal that the logging tool can measure), the axial forward detection distance of the logging tool can be defined.

[0120] S4. Perform far-detection transmission using a near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions, including the following steps:

[0121] As Figure 12 shown, combine and connect the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions as a pre-emission module to the electromagnetic wave far-detection receiving sub-section to form a far-detection electromagnetic wave logging tool with a pre-emission sub-section.

[0122] For example, when the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions of the present invention emits at four frequencies (1 KHz - 64 KHz) of F1, F2, F3, and F4, it can be combined with the electromagnetic wave far-detection receiving sub-section as a pre-emission module to form a far-detection electromagnetic wave logging tool with a pre-emission sub-section.

[0123] As Figure 12 shown, in the antenna structure of a conventional electromagnetic wave far-detection instrument, the transmitting antenna 5 is placed above the screw 4, far from the drill bit 2, and the forward detection ability is weak; the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions has a far-detection transmission function. When it is used as the electromagnetic wave far-detection transmitting end section, the transmitting antenna 5 is placed below the screw 4, realizing the forward movement of far-detection transmission, shortening the distance between it and the drill bit 2 (8 - 10 m), and greatly increasing the forward detection ability of the far-detection instrument. At the same time, the borehole resistivity information provided by the logging tool can also provide a basis for the electromagnetic wave far-detection radial edge detection to invert the formation interface.

[0124] For example, a model was established based on the parameters of the 6.75-inch prototype of the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions of the present invention for numerical simulation, forming an instrument resistivity conversion chart, and analyzing the axial forward detection and radial edge detection characteristics of the logging tool.

[0125] Resistivity chart: Set the formation model as a homogeneous formation with a resistivity of 0.1 - 1000 ohm-meters, the near source distance L1 is 0.5 m, the far source distance L2 is 0.8 m, the number of turns of the coils of the transmitting antenna 5, the first receiving antenna 6, and the second receiving antenna 7 is 10, the coil diameter is 0.165 m, the current intensity is 1 A, and the transmitting frequencies are 2 MHz and 400 kHz. Figure 13 and Figure 14 are the formation resistivity charts plotted for the amplitude ratio and phase difference when only the transmitting antenna 5, the first receiving antenna 6, and the second receiving antenna 7 are included in the homogeneous formation without the influence of the logging tool structure. The formation resistivity information can be obtained by converting the measured signals according to the chart.

[0126] Axial forward detection characteristics: When investigating the axial forward detection characteristics of the logging tool this time, a plot was drawn by the amplitude ratio Att of the adjacent first receiving antenna 6 and the second receiving antenna 7 under different resistivity contrast formation models. The axial forward detection ability of the logging tool was defined by setting the influence degree of the formation in front of the bit 2 on the logging tool response.

[0127] Figure 15 For the logging tool response curve graphs when the instrument enters the 1 Ω·m formation from 1000 Ω·m, 20 Ω·m, 10 Ω·m, and 2 Ω·m at the transmitting frequency of 400 kHz, they were normalized. It was defined that the logging tool response being affected by 5% of the formation in front of the bit 2 was the forward detection distance. When the logging tool was in medium 1 and medium 2, the responses of the logging tool in infinite homogeneous media 1 and 2 were used as the standards for normalization respectively. From Figure 15 it can be seen that when the logging tool crosses the boundary layer interface, the response of the voltage signal will change accordingly, indicating that the logging tool can identify the interface in front of the formation and has the forward detection ability. Moreover, when entering the low-resistivity formation from the high-resistivity formation, the greater the contrast, the greater the voltage change, and thus the farther the forward detection distance.

[0128] Radial edge detection characteristics: When investigating the radial edge detection characteristics of the logging tool this time, a plot was drawn by the characteristic curves of the voltage Vzz signal (z transmitting, z receiving of the first receiving antenna 6) received by the first receiving antenna 6 under different resistivity contrast formation models. The radial edge detection ability of the logging tool was defined by setting the voltage signal amplitude threshold.

[0129] When the transmitting frequency was 400 kHz, the response characteristics of the voltage geological signal of the logging tool were calculated through numerical simulation. A detection threshold value of 50 nV was set, and the response curves of the logging tool were given under four different contrasts (100:1, 20:1, 10:1, 2:1). The edge detection ability of the logging tool was clarified by discussing the logging responses of the logging tool at different contrast formation interfaces.

[0130] Figure 16 For the logging tool response curve graphs when the logging tool was in the high-resistivity formations of 1000 Ω·m, 20 Ω·m, 10 Ω·m, and 2 Ω·m respectively, taking the amplitude value of the second receiving antenna 7 at a far source distance as the received signal value, it can be seen that when the threshold value was 50 nV, the edge detection distances of the logging tool in the formations with contrasts of 100:1, 20:1, 10:1, and 2:1 were 0.8 m, 0.77 m, 0.74 m, and 0.69 m respectively, and the greater the formation contrast, the farther the edge detection distance.

[0131] The near-bit dual gamma and electromagnetic wave imaging logging method and instrument of the present invention are small in size (a short section about 1 meter long), and can complete the measurement of formation parameters such as azimuth natural gamma and electromagnetic waves. The present invention can realize the measurement of near-bit azimuth gamma and electromagnetic wave information, precise geological steering of complex reservoirs, and precise description of oil and gas reservoir structures, meeting the production requirements in oil and gas exploration and development.

[0132] Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A near-bit gamma electromagnetic wave imaging logging tool with functions of far detection emission and power generation, characterized in that It includes a drill collar body, a water eye is axially arranged inside the drill collar body, a transmitting antenna is arranged outside the lower end of the drill collar body, and a first receiving antenna and a second receiving antenna are arranged outside the upper end of the drill collar body; a first antenna port is also arranged on the drill collar body between the first receiving antenna and the second receiving antenna, and a second antenna port is arranged between the second receiving antenna and the transmitting antenna; A sealing and fastening sleeve, a circuit framework, a lower flow deflector and a mud turbine power generation device are arranged in the water eye. The sealing and fastening sleeve and the lower flow deflector fix the circuit framework in the water eye. The circuit framework has an accommodation cavity. The middle part of the mud turbine power generation device is located in the accommodation cavity. The lower end of the mud turbine power generation device is connected to the lower flow deflector. The upper end of the mud turbine power generation device penetrates through the sealing and fastening sleeve. An azimuth gamma measurement circuit is arranged in the circuit framework.

2. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 1, characterized in that, The normal directions of the first receiving antenna and the second receiving antenna are the same as the axis of the drilling direction, and the transmitting antenna has an included angle with the axis of the drilling direction.

3. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 1, characterized in that, A wear-resistant band is also arranged between the second receiving antenna and the second antenna port.

4. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 1, characterized in that, First antenna protection covers are arranged outside both the first receiving antenna and the second receiving antenna, and a second antenna protection cover is also arranged outside the transmitting antenna.

5. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 1, characterized in that, The circuit framework includes a transmitting chamber, a first receiving chamber, a second receiving chamber, a main control chamber and a gamma chamber; Among them, a main control processing circuit and a sector sensor are arranged in the main control chamber, an azimuth gamma measurement circuit is arranged in the gamma chamber, a transmitting circuit is arranged in the transmitting chamber, and a power module and a receiving circuit are arranged in both the first receiving chamber and the second receiving chamber.

6. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 5, characterized in that, The main control processing circuit includes an AD acquisition circuit, a data processing circuit, a signal control circuit and a DA conversion circuit connected in sequence. Among them, the AD acquisition circuit is connected to the two receiving circuits, the data processing circuit is connected to the azimuth gamma measurement circuit, the signal control circuit is connected to other instruments through a communication drive interface, and the DA acquisition and conversion circuit is connected to the transmitting circuit.

7. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 6, characterized in that, The transmitting circuit includes a power supply filtering circuit, a transmitting amplification circuit and a transmitting tuning circuit connected in sequence; The receiving circuit includes a filtering amplification circuit and a receiving tuning circuit connected in sequence; The azimuth gamma measurement circuit includes a sector processing circuit and an integrated gamma detector. Among them, the sector sensor is connected to the sector processing circuit, and the integrated gamma detector is connected to the sector processing circuit.

8. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to any one of claims 5-7, characterized in that, The power module is electrically connected to the mud turbine power generation device.

9. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to any one of claims 1-7, characterized in that, The mud turbine power generation device includes a guide wheel, an impeller, a connecting sleeve, a sealing housing, a pressure-bearing sealing cylinder, a mud bearing, a transmission shaft, a magnetic coupling component, a sealing sleeve and a generator; Wherein, the lower end of the sealed housing is connected to the pressure-bearing sealed cylinder, the upper end of the sealed housing is in dynamic sealing connection with the first end of the connecting sleeve, and the second end of the connecting sleeve is fixedly connected to the impeller; the generator is arranged inside the sealed housing, the shaft of the generator is connected to the first end of the transmission shaft, and the sealing sleeve is sleeved on the shaft of the generator and the transmission shaft; The second end of the transmission shaft penetrates through the central hole of the impeller, and the guide wheel is fixedly connected to the transmission shaft and is located between the second end of the transmission shaft and the impeller; A first mud bearing, a second mud bearing and a third mud bearing are arranged between the first end of the transmission shaft and the guide wheel. The impeller is fixedly connected to the outer ring of the first mud bearing. The magnetic coupling assembly is arranged between the second mud bearing and the third mud bearing. The connecting sleeve is fixedly connected to the outer rings of the second mud bearing and the third mud bearing. The magnetic coupling assembly is arranged inside the connecting sleeve. The inner cylinder of the magnetic coupling assembly is fixedly connected to the transmission shaft, and the outer cylinder of the magnetic coupling assembly is fixedly connected to the connecting sleeve.

10. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 9, characterized in that, The mud turbine power generation device further includes an impact-proof cap, and the second end of the transmission shaft is in threaded fixed connection with the impact-proof cap.

11. The near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to claim 9, characterized in that, The mud turbine power generation device further includes an oil balance piston. An oil cavity is axially arranged inside the transmission shaft, and the oil balance piston is slidably connected to the oil cavity.

12. A near-bit electromagnetic wave imaging logging method, characterized in that, Performing formation resistivity measurement by using the near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to any one of claims 1-11, including the following steps: The transmitting antenna emits an electromagnetic wave signal at a set angle. The electromagnetic wave signal is equivalent to an axial Z component and a radial X component orthogonal to the axial component. The first receiving antenna and the second receiving antenna receive the coaxial ZZ component and the orthogonal XZ component; Obtain the relationship between the amplitude ratio and phase difference of the signals received by the first receiving antenna and the second receiving antenna and the formation resistivity through numerical simulation, and draw a chart. Convert the measured signal into formation resistivity information according to the chart.

13. A method for near-bit electromagnetic wave imaging logging, characterized in that, Performing radial edge detection and axial forward detection by using the near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to any one of claims 1-11, including the following steps: The transmitting antenna emits an electromagnetic wave signal at a set angle. The electromagnetic wave signal is equivalent to an axial Z component and a radial X component orthogonal to the axial component. When the first receiving antenna and the second receiving antenna respectively receive the coaxial ZZ component and the orthogonal XZ component, the formation azimuth resistivity is characterized by the azimuth angle of the electromagnetic wave measurement signal to achieve radial edge detection; The transmitting antenna emits an electromagnetic wave signal at a set angle. The electromagnetic wave signal is equivalent to an axial Z component and a radial X component orthogonal to the axial component. When the first receiving antenna and the second receiving antenna both receive the orthogonal XZ component and the coaxial ZZ component, measure the formation resistivity in front of the drill bit to achieve the axial forward detection function.

14. A near-bit electromagnetic wave imaging logging method, characterized in that, Performing axial forward detection distance measurement by using the near-bit gamma electromagnetic wave imaging logging tool with far-detection emission and power generation functions according to any one of claims 1-11, including the following steps: Establish a resistivity forward detection model; Based on the resistivity forward detection model, the response characteristic curve of the receiving antenna is calculated according to the magnetic field intensities at the first receiving antenna and the second receiving antenna. By selecting the cut-off value of the difference between the geological signal of the logging tool and the uniform space response, the axial forward detection distance of the logging tool is determined.

15. A method for near-bit electromagnetic wave imaging logging, characterized in that, Performing far-detection transmission by the near-bit gamma electromagnetic wave imaging logging tool with far-detection transmission and power generation functions according to any one of claims 1-11, comprising the following steps: Regarding the near-bit gamma electromagnetic wave imaging logging tool as a pre-emission module and combining and connecting it with the electromagnetic wave far-detection receiving sub-section.

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