Optical fiber sensing integrated system for logging while drilling photoelectric information transmission

Abstract

The invention provides an optical fiber sensing integrated system for photoelectric information transmission of logging while drilling, and relates to the technical field of optical fiber communication and optical fiber sensing. The optical fiber sensing integrated system comprises a ground signal demodulation module, a wellhead optical fiber connection module and an underground photoelectric communication module, the ground signal demodulation module sends broadband light to the underground photoelectric communication module, demodulates a returned fiber grating sensing signal, modulates and sends a downlink control instruction and demodulates an uplink electro-optical conversion signal; optical fiber grating sensing signals and electro-optical conversion signals are combined, shunted and subjected to direction control on the same single-mode optical fiber; the wellhead optical fiber connection module is connected with the underground photoelectric communication module, the underground photoelectric communication module performs optical fiber sensing on different physical quantities through an optical fiber grating sensor and converts an electric signal of the underground photoelectric communication module to form an electro-optical conversion signal, and the application helps to improve the reliability and stability of data transmission.

Description

Technical Field

[0001] This invention relates to the fields of optical fiber communication and optical fiber sensing technology, and in particular to an integrated optical fiber sensing system for photoelectric information transmission during logging. Background Technology

[0002] In recent years, with the continuous development of sensor and information technologies, people have increasingly higher requirements for information transmission. Traditional electrical communication lines can no longer meet the bandwidth demands, and optical fibers have expanded beyond backbone network applications to transmit data to end users. In dedicated systems, optical fiber communication technology has been applied between devices and sensors. With the development of information technology, sensors are increasingly used in production and daily life. Surface ships, large aircraft, spacecraft, and smart homes all require the detection of various types of information—electrical, acoustic, mechanical, and video—through electrical and optical means, giving rise to sensor networks.

[0003] Chinese Patent Publication No. CN105471510B discloses an integrated system for fiber optic grating sensing and fiber optic communication, including an optical fiber modulation and demodulation module and N communication sensing channels. Each communication sensing channel is based on optical fiber, with grating sensors deployed on the fiber. Each optical fiber has a communication sensing separation interface and a communication module at its transmitting end, and a communication module at its receiving end. The communication module at the transmitting end receives the communication optical signal transmitted from the other end through the communication sensing separation interface, and the communication module at the receiving end receives the communication optical signal transmitted from the other end through the optical fiber. The communication sensing separation interface receives the optical signal... The fiber optic modem outputs a sensing optical signal and receives a communication optical signal from the local communication module. During transmission, the sensing and communication optical signals are optically coupled to form a beam of light, which is then sent into the fiber. During reception, the communication-sensor separation interface separates the reflected sensing optical signals from the various grating sensors in the fiber and the communication optical signals received from the other end. The reflected sensing optical signals are sent to the fiber optic modem, and the communication optical signals received from the other end are sent to the local communication module. The fiber optic modem demodulates the sensing optical signals reflected from the grating sensors to obtain sensing data. However, this approach, which only couples the sensing and communication optical signals at the transmitting end of each communication sensing channel and then separates them by power at the receiving end, is insufficient to effectively suppress crosstalk between sensing signals and ensure data transmission accuracy and stability in long-distance deep well operations. Therefore, it is essential to provide an integrated fiber optic sensing system for photoelectric information transmission in logging-while-drilling to improve data transmission reliability and stability. Summary of the Invention

[0004] In view of this, the present invention proposes an integrated fiber optic sensing system for photoelectric information transmission in logging while drilling.

[0005] This invention provides an integrated fiber optic sensing system for photoelectric information transmission in logging-while-drilling, comprising a surface signal demodulation module, a wellhead fiber optic connection module, and a downhole photoelectric communication module, wherein... The ground signal demodulation module is connected to the wellhead optical fiber connection module. The ground signal demodulation module sends broadband light to the downhole optoelectronic communication module to excite the fiber Bragg grating sensor and demodulates the returned fiber Bragg grating sensing signal to obtain optical fiber sensing information. It also modulates and sends downlink control commands and demodulates uplink electro-optical conversion signals to enable the fiber Bragg grating sensing signal and the electro-optical conversion signal to be combined, split, and directional controlled on the same single-mode optical fiber in the optical fiber compartment. The wellhead fiber optic connection module is connected to the downhole optoelectronic communication module. The downhole optoelectronic communication module senses different physical quantities through the fiber optic grating sensor and returns the corresponding fiber optic grating sensing signals to the ground signal demodulation module along the single-mode fiber. It also collects, encodes, and performs electro-optic conversion on the electrical signals of the downhole optoelectronic communication module to form an uplink electro-optic converted signal.

[0006] Based on the above technical solutions, preferably, the ground signal demodulation module includes an optical fiber sensing demodulation component, an optical amplifier, a first optical circulator, a communication modem, a second optical circulator, and a wavelength division multiplexer, wherein... The fiber optic sensing demodulation component is connected to one end of the optical amplifier and the third end of the first optical circulator, respectively. The other end of the optical amplifier is connected to the first end of the first optical circulator. The second end of the first optical circulator is connected to one end of the wavelength division multiplexer and the second end of the second optical circulator, respectively. The first and third ends of the second optical circulator are both connected to the communication modem. The communication modem is also connected to the downhole optoelectronic communication module.

[0007] Based on the above technical solutions, preferably, the wellhead fiber optic connection module includes a smooth ring, a winding machine, and a photoelectric wet connector connected in sequence. One end of the smooth ring is connected to the other end of the wavelength division multiplexer, and one end of the photoelectric wet connector is connected to the downhole photoelectric communication module.

[0008] More preferably, the downhole optoelectronic communication module includes an optical fiber housing, an optical coupler, a photodetector, a communication demodulator, an acousto-optic modulator, an optical isolator, and a fiber Bragg grating sensor, wherein... The fiber optic cable compartment is connected to one end of the optoelectronic wet connector and the first port of the optical coupler, respectively. The second port of the optical coupler is connected to the communication demodulator through the photodetector. The other end of the communication demodulator is connected to the communication modem. The third port of the optical coupler is connected to the first end of the acousto-optic modulator. The second end of the acousto-optic modulator is connected to the communication modem. The third end of the acousto-optic modulator is connected to one end of the optical isolator. The other end of the optical isolator is connected to the fourth port of the optical coupler through the fiber Bragg grating sensor.

[0009] More preferably, the splitting ratio between the second port, the third port and the fourth port of the optical coupler is 20:40:20.

[0010] More preferably, the fiber optic grating sensing signal is transmitted in the C-band, and the electro-optic conversion signal converted by the acousto-optic modulator from the electrical sensor is transmitted in the O-band or L-band. The fiber optic grating sensing signal and the electro-optic conversion signal are transmitted separately and in parallel in the same single-mode optical fiber through the wavelength division multiplexer. The electrical sensor is installed in the fiber optic parameter short section downhole.

[0011] More preferably, the fiber Bragg grating sensor is deployed in the fiber optic parameter section downhole and connected to the single-mode fiber via the optical coupler. The fiber Bragg grating sensor is used to sense various physical quantities during drilling and to return the wavelength shift caused by these physical quantities to the surface via the single-mode fiber for demodulation by the fiber Bragg grating sensing demodulation assembly.

[0012] More preferably, the fiber Bragg grating sensor includes multiple fiber Bragg gratings distributed axially or circumferentially along the downhole fiber optic parameter short section, and the multiple fiber Bragg gratings are used to measure one or more physical quantities among downhole temperature, triaxial acceleration, drilling pressure and torque.

[0013] More preferably, the optical isolator is disposed between the acousto-optic modulator and the optical isolator, and the optical isolator is used to provide unidirectional transmission isolation for the fiber Bragg grating sensor.

[0014] More preferably, the communication demodulator is used to receive the downlink control command and to encode and manage the uplink electro-optical conversion signal. The encoding and management includes time-division multiplexing or code-division multiplexing of the sampling data of different electrical sensors.

[0015] The fiber optic sensing integrated system for photoelectric information transmission in logging-while-drilling provided by this invention has the following advantages over existing technologies: (1) By integrating fiber optic grating sensing and optoelectronic communication into the same system, a single-mode fiber is used to transmit fiber optic sensing signals and electro-optical converted communication signals simultaneously, realizing real-time monitoring and data transmission integration during logging while drilling. In the fiber optic cable compartment, a single-mode fiber is used for combining, splitting and directional control, avoiding the parallel laying of multiple fibers or multiple independent transmission cables, simplifying the downhole tool structure, reducing installation and maintenance difficulty. The fiber itself has electromagnetic immunity. By using fiber optic grating sensing signals and optical signal communication, the electromagnetic interference of cable systems is greatly reduced, improving the data transmission accuracy and stability in high temperature, high pressure and strong electromagnetic environment. With the help of fiber optic grating sensors, high-sensitivity, multi-point distributed measurement of various physical quantities such as temperature, pressure, vibration and strain can be performed. At the same time, through broadband optical excitation and demodulation of the ground signal demodulation module, multi-point long-distance measurement and backhaul along the well section can be realized. Downlink control and uplink measurement data / status information are transmitted simultaneously on the same single-mode fiber, improving the utilization rate of communication links.

[0016] (2) By setting an optical amplifier between the optical fiber sensing demodulation component and the first optical circulator, the downlink broadband light and the uplink return light are amplified and compensated, the transmission loss is reduced, and the signal-to-noise ratio of the fiber optic grating sensing signal and the communication signal is improved. It is suitable for long well depth and strong attenuation conditions. Furthermore, the combined use of the first optical circulator, the second optical circulator and the wavelength division multiplexer enables the fiber optic grating sensing signal and the electro-optical conversion communication signal to be transmitted on different wavelength channels, realizing the combining / splitting on the same single-mode fiber, the directional transmission and effective isolation of the uplink and downlink optical paths, and reducing channel crosstalk, thereby improving the stability of multi-service co-fiber transmission. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an integrated fiber optic sensing system for photoelectric information transmission during logging-while-drilling, provided by the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Fiber optic sensing demodulation assembly; 2. Optical amplifier; 3. First optical circulator; 4. Communication modem; 5. Second optical circulator; 6. Wavelength division multiplexer; 7. Smooth ring; 8. Winding machine; 9. Optical wet connector; 10. Fiber optic cable compartment; 11. Optical coupler; 12. Photodetector; 13. Communication demodulator; 14. Acousto-optic modulator; 15. Optical isolator; 16. Fiber Bragg grating sensor. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "connected" or "linked" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0022] refer to Figure 1 This invention provides an integrated fiber optic sensing system for photoelectric information transmission in logging-while-drilling, comprising a surface signal demodulation module, a wellhead fiber optic connection module, and a downhole photoelectric communication module, wherein... The ground signal demodulation module is connected to the wellhead fiber optic connection module. The ground signal demodulation module sends broadband light to the downhole optoelectronic communication module to excite the fiber Bragg grating sensor 16 and demodulates the returned fiber Bragg grating sensing signal to obtain fiber optic sensing information. It also modulates and sends downlink control commands and demodulates uplink electro-optical conversion signals so that the fiber Bragg grating sensing signal and the electro-optical conversion signal are combined, split, and directional controlled on the same single-mode fiber in the fiber optic cable compartment 10. The wellhead fiber optic connection module is connected to the downhole optoelectronic communication module. The downhole optoelectronic communication module uses fiber optic grating sensor 16 to sense different physical quantities and returns the corresponding fiber optic grating sensing signals to the ground signal demodulation module along a single-mode fiber. It also collects, encodes, and performs electro-optic conversion on the electrical signals of the downhole optoelectronic communication module to form an uplink electro-optic converted signal.

[0023] A single-mode optical fiber is used to transmit the electro-optical converted signal from the electro-optical sensor and the fiber Bragg grating sensing signal. Since both signals are transmitted within a single fiber core, wavelength division multiplexing (WDM) is required. The fiber Bragg grating sensor 16 operates at 1550nm (C-band), while the electro-optical signal operates in either the O-band or L-band. To prevent crosstalk, a WDM multiplexer 6 separates the wavelengths and connects them to their respective demodulators. Compared to the previous example, this scheme has several advantages: firstly, the connection loss (0.5dB) of the WDM 6 is lower than that of fan-in / fan-out devices; secondly, the WDM 6 can be installed in an instrument room, preventing damage from the harsh underground environment.

[0024] Furthermore, the ground signal demodulation module includes an optical fiber sensing demodulation component 1, an optical amplifier 2, a first optical circulator 3, a communication modem 4, a second optical circulator 5, and a wavelength division multiplexer 6, wherein... The fiber optic sensing demodulation component 1 is connected to one end of the optical amplifier 2 and the third end of the first optical circulator 3, respectively. The other end of the optical amplifier 2 is connected to the first end of the first optical circulator 3. The second end of the first optical circulator 3 is connected to one end of the wavelength division multiplexer 6 and the second end of the second optical circulator 5, respectively. The first and third ends of the second optical circulator 5 are both connected to the communication modem 4. The communication modem 4 is also connected to the downhole optoelectronic communication module.

[0025] The wellhead fiber optic connection module includes a smooth ring 7, a winding machine 8, and an optical-optical wet connector 9 connected in sequence. One end of the smooth ring 7 is connected to the other end of the wavelength division multiplexer 6, and one end of the optical-optical wet connector 9 is connected to the downhole optical-optical communication module.

[0026] The downhole optoelectronic communication module includes an optical fiber housing 10, an optical coupler 11, a photodetector 12, a communication demodulator 13, an acousto-optic modulator 14, an optical isolator 15, and a fiber Bragg grating sensor 16. The fiber optic cable compartment 10 is connected to one end of the optoelectronic wet connector 9 and the first port of the optical coupler 11. The second port of the optical coupler 11 is connected to the communication demodulator 13 through the photodetector 12. The other end of the communication demodulator 13 is connected to the communication modem 4. The third port of the optical coupler 11 is connected to the first end of the acousto-optic modulator 14. The second end of the acousto-optic modulator 14 is connected to the communication modem 4. The third end of the acousto-optic modulator 14 is connected to one end of the optical isolator 15. The other end of the optical isolator 15 is connected to the fourth port of the optical coupler 11 through the fiber optic grating sensor 16.

[0027] In this embodiment, by setting an optical amplifier 2 between the fiber optic sensing demodulation component 1 and the first optical circulator 3, the downlink broadband light and uplink return light are amplified and compensated, reducing transmission loss and improving the signal-to-noise ratio of the fiber Bragg grating sensing signal and communication signal. This is suitable for long well depths and strong attenuation conditions. The combined use of the first optical circulator 3, the second optical circulator 5, and the wavelength division multiplexer 6 enables the fiber Bragg grating sensing signal and the electro-optical converted communication signal to be transmitted on different wavelength channels, realizing the combining / splitting on the same single-mode fiber, directional transmission and effective isolation of uplink and downlink optical paths, reducing channel crosstalk, and improving the stability of multi-service co-fiber transmission.

[0028] The communication modem 4 establishes an optical communication link with the downhole optoelectronic communication module through the second optical circulator 5, thereby enabling efficient modulation and transmission of downlink control commands and sensitive demodulation and decoding of uplink electro-optical conversion signals. This improves the communication rate and control accuracy between the surface and the well, providing a reliable channel for real-time control of logging while drilling.

[0029] The smooth ring 7, in conjunction with the winding machine 8, effectively releases the torsional stress on the optical fiber during drill string rotation and lifting, preventing repeated tangling and mechanical damage, and ensuring the continuity and stability of the optical path from the wellhead to the downhole. The winding machine 8 enables orderly winding and tension control of the optical fiber, reducing the impact of fiber bending and stretching on signal quality and lifespan, which is beneficial for construction and use in long well sections and deep wells. The photoelectric wet connector 9 enables reliable pluggable connection between the downhole optical fiber and the photoelectric communication module in liquid / high-pressure environments, ensuring the sealing and pressure resistance of the connector.

[0030] The fiber optic cable compartment 10, in conjunction with the optical coupler 11, splits and combines the single-mode fiber from the wellhead downhole. One path is used for photoelectric conversion and demodulation of communication signals, while the other is used to drive the fiber Bragg grating sensor 16 and transmit the sensing signals back, thus achieving integrated communication and sensing within the same fiber downhole, reducing the need for independent optical cables and channel resources. From the second port of the optical coupler 11 to the photodetector 12 and then to the communication demodulator 13, photoelectric conversion and demodulation of the downlink optical communication signal are achieved, restoring the ground control commands to downhole electrical signals. The acousto-optic modulator 14, connected to the communication modem 4, modulates the downhole electrical signals onto the uplink optical carrier, achieving uplink electro-optic conversion. Therefore, a complete bidirectional communication link can be completed downhole, reducing complex electronic interfaces and intermediate cascading, and improving system reliability.

[0031] By constructing a pure optical domain channel using optical devices such as optical coupler 11, optical isolator 15, and acousto-optic modulator 14, and with limited electrical detection and demodulation links, the fiber optic sensing integrated system can maintain high reliability and data integrity even under high temperature, high pressure, and strong electromagnetic interference environments.

[0032] In one example, the splitting ratio between the second, third, and fourth ports of the optical coupler 11 is 20:40:20. An optical isolator 15 is positioned between the acousto-optic modulator 14 and the optical isolator 15, providing unidirectional transmission isolation for the fiber Bragg grating sensor 16. The communication demodulator 13 receives downlink control commands and performs encoding management on the uplink electro-optical conversion signals. Encoding management includes time-division multiplexing or code-division multiplexing of the sampled data from different electrical sensors.

[0033] The fiber Bragg grating (FBG) sensing signal is transmitted in the C-band, while the electro-optical conversion signal from the electrical sensor, converted by the acousto-optic modulator 14, is transmitted in the O-band or L-band. The FBG sensing signal and the electro-optical conversion signal are transmitted discretely and in parallel on the same single-mode fiber via a wavelength division multiplexer 6. The electrical sensor is installed in a fiber optic parameter section downhole. The FBG sensor 16 is also installed in the fiber optic parameter section downhole and connected to the single-mode fiber via an optical coupler 11. The FBG sensor 16 is used to sense various physical quantities during drilling and to return the wavelength shift caused by these physical quantities to the surface via the single-mode fiber for demodulation by the FBG sensing demodulation assembly.

[0034] The fiber optic grating sensor 16 is installed in the fiber optic parameter section downhole and connected to the single-mode fiber through the optical coupler 11. The fiber optic grating sensor 16 is used to sense various physical quantities during the drilling process and return the wavelength shift caused by the physical quantities to the ground through the single-mode fiber for demodulation by the fiber optic grating sensing demodulation component.

[0035] Furthermore, in fiber-optic logging while drilling, downhole drilling information (temperature, acceleration, drilling pressure, torque, etc.) is acquired through fiber optic parameter subsections. These subsections contain both an electrical sensor and a fiber optic grating sensor 16. Sensor information is transmitted via fiber optic cable. The electrical sensor transmits the signal after electro-optic conversion, while the fiber optic grating sensor 16 transmits the reflected wavelength of the fiber optic grating. Since both sensors utilize optical signals for transmission within the same fiber, different wavelengths are chosen to avoid crosstalk between the optical signal generated by the electrical sensor after electro-optic conversion and the wavelength signal of the fiber optic grating sensor 16, which could affect the demodulation results.

[0036] In one example, wavelength division multiplexer 6 is a 1310nm / 1550nm wavelength division multiplexer, and the fiber optic sensing demodulation component 1 uses a 1550nm fiber Bragg grating demodulator to output a light source and receive the reflected spectrum of the fiber Bragg grating sensor 16 for sensing and demodulation. The fiber Bragg grating sensing system uses the C-band, i.e., 1525nm-1565nm. The light passes through one port of the first optical circulator 3, then through the wavelength division multiplexer 6, and enters the fiber optic link. After reaching the downhole, it is detected by the optical coupler 11, and finally, the reflected spectrum of the fiber Bragg grating sensor 16 is returned through the coupler, entering the sensing demodulation component from the second port of the first circulator and then reaching the sensing demodulation component from the third port for sensing and demodulation. Optical isolation is used to prevent the light source in the sensing demodulation component from entering the acousto-optic modulator 14 and causing module damage. The fiber Bragg gratings are installed in the downhole fiber optic parameter section, containing eight fiber Bragg gratings, which are used in different arrangements for sensing temperature, acceleration, drilling pressure, and torque during the drilling process. When the physical quantity of the fiber optic section changes, it will affect the fiber optic grating, causing the fiber optic grating wavelength to shift. The shift is detected by the ground-based sensing demodulation component and converted into the physical quantity to be measured.

[0037] The communication modem 4 uses a wavelength of 1310nm. The light passes through one port of the second circulator, then through the wavelength division multiplexer 6, and enters the fiber optic link. After reaching the downhole, it passes through the optical coupler 11 to the photodetector 12. After photoelectric conversion, the information is transmitted to the downhole communication demodulator 13. Because the transmission wavelength is 1310nm, it will not interfere with the fiber Bragg grating sensor 16. The downhole communication demodulator 13 and the acousto-optic modulator 14 are crucial links in signal interaction. The downlink signal of the communication modem 4 is mainly used for commands and sending control instructions. The downhole communication demodulator 13 is used for signal reception and demodulation, and for configuring parameters of downhole electrical devices. The uplink signal mainly transmits the information collected by the downhole electrical sensors back to the surface after electro-optic conversion. The acousto-optic modulator 14 modulates the electro-optic signal into specific pulsed light or frequency-shifted light, injects it into the sensing fiber, and thus transmits the downhole electrical sensor information.

[0038] The downhole electrical sensor converts the electrical signal into an optical signal via an acousto-optic modulator 14, which is then transmitted to the surface via an optical coupler 11. After passing through a wavelength division multiplexer 6, the signal enters through port two of the second circulator and reaches the communication modem 4 through port three for data acquisition and analysis. The wavelength division multiplexer 6 ensures that the electro-optically converted signal enters the communication modem 4 through the 1310nm port, thus avoiding interference with the optical sensing demodulation components.

[0039] The fiber optic sensing integrated transmission link for logging while drilling mainly adopts wavelength division and optical isolation to achieve the effect of separate and parallel transmission of fiber optic grating sensing information and electro-optic conversion information in a single optical fiber.

[0040] In one example, a fiber optic sensing demodulation component 1 located on the ground generates broadband or swept-frequency light, which is amplified by an optical amplifier 2 and then sent to a first optical circulator 3. The first optical circulator 3 directs the light from the demodulation component into a wavelength division multiplexer 6. After being multiplexed with the communication wavelength in the wavelength division multiplexer 6, the light is transmitted to the underground via a smoothing ring 7, a winding machine 8, a fiber optic cable cassette 10, and an optoelectronic wet connector 9. The single-mode fiber in the underground enters an optical coupler 11, which distributes the light to an acousto-optic modulator 14, an optical isolator 15, and an array of fiber Bragg grating sensors 16. The light incident on each fiber Bragg grating is reflected at its respective Bragg wavelength. The reflected light carries the measured information such as temperature and strain, and returns to the optical coupler 11 after passing through the optical isolator 15 and the acousto-optic modulator 14, before being transmitted back to the ground along the original optical path. After the reflected light returns to the ground via the top drive transmission unit and wavelength division multiplexer 6, it is guided by the first optical circulator 3 to the fiber optic sensing demodulation component 1. The demodulation component analyzes the center wavelength of the spectrum and outputs the sensing data of each measurement point. In this channel, the acousto-optic modulator 14 can perform gated or frequency-shifted modulation on the probe light to distinguish different sensing segments in time division / frequency division and improve the signal-to-noise ratio.

[0041] The uplink and downlink communication signals use different wavelengths than the FBG (Fast-Fast Generation Gear), sharing the same optical fiber with the FBG measurement light via wavelength division multiplexer 6. The downlink communication process includes: the ground communication modem 4 modulates control commands and data onto an optical carrier, which is then input to the wavelength division multiplexer 6 via the second optical circulator 5. The wavelength division multiplexer 6 multiplexes the downlink communication light with other optical paths and sends it downhole through the top drive transmission unit, entering the optical coupler 11. The optical coupler 11 couples the downlink communication light to the photodetector 12, which converts the optical signal into an electrical signal, which is then sent to the communication demodulator 13. The communication demodulator 13 performs baseband demodulation and data parsing, providing control commands and configuration parameters for the downhole electronic equipment.

[0042] The uplink communication process includes: Downhole electronic equipment sends measurement data and status information to an acousto-optic modulator 14. The acousto-optic modulator 14 modulates the intensity or frequency shift of the passing light, writing data onto the optical carrier. The modulated uplink light enters the backbone optical fiber via an optical isolator 15 and is injected into the return optical path via an optical coupler 11, then sent back to the surface via the top drive transmission unit. On the surface, a wavelength division multiplexer 6 separates the uplink communication light from the optical fiber and guides it to a communication modem 4 via a second optical circulator 5. The communication modem 4 performs photoelectric conversion and digital demodulation of the optical signal, outputting downhole data to a host computer or surface monitoring system.

[0043] The wellhead fiber optic connection module achieves a twist-free optical connection between the rotating and fixed parts via a smooth ring 7, ensuring that the fiber optic cable is not damaged by twisting during continuous drill string rotation. The winding machine 8 and fiber optic cable compartment 10 are used to store and automatically wind up and unwind the fiber optic cable, adapting to length changes during drill string tripping and drill pipe splicing. The photoelectric wet connector 9 provides a reliable optical connection interface in liquid and high-pressure environments, facilitating the rapid installation and replacement of downhole tools.

[0044] In this embodiment, by integrating fiber optic grating sensing and optoelectronic communication into the same system, a single-mode fiber is used to simultaneously transmit fiber optic sensing signals and electro-optically converted communication signals, achieving integrated real-time monitoring and data transmission during logging-while-drilling. The fiber optic cable compartment 10 employs a single-mode fiber for combining, splitting, and direction control, avoiding the parallel laying of multiple fibers or independent transmission cables, simplifying the downhole tool structure, and reducing installation and maintenance difficulty. The fiber itself possesses electromagnetic immunity; by utilizing fiber optic grating sensing signals and optical signal communication, the electromagnetic interference of cable systems is significantly reduced, improving the reliability and stability of data transmission in high-temperature, high-pressure, and strong electromagnetic environments. With the help of the fiber optic grating sensor 16, high-sensitivity, multi-point distributed measurements of various physical quantities such as temperature, pressure, vibration, and strain can be performed. Through broadband optical excitation and demodulation by the ground signal demodulation module, multi-point long-distance measurement and transmission along the well section are achieved. The surface signal demodulation module performs optical domain modulation on downlink control commands and demodulates uplink electro-optical converted signals, enabling bidirectional communication between the surface and the wellbore. It simultaneously transmits downlink control and uplink measurement data / status information over the same single-mode fiber, improving communication link utilization. By acquiring, encoding, and electro-optically converting downhole electrical signals and uplinking them in real time, as well as rapidly responding to control commands issued from the surface, real-time monitoring and precise control of the logging-while-drilling tool status and measurement process can be achieved, shortening the decision feedback loop time.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fiber optic sensing integrated system for photoelectric information transmission in logging-while-drilling, characterized in that, It includes a surface signal demodulation module, a wellhead fiber optic connection module, and a downhole optoelectronic communication module, among which, The ground signal demodulation module is connected to the wellhead optical fiber connection module. The ground signal demodulation module sends broadband light to the downhole optoelectronic communication module to excite the fiber grating sensor (16) and demodulates the returned fiber grating sensing signal to obtain optical fiber sensing information. It also modulates and sends downlink control commands and demodulates uplink electro-optical conversion signals so that the fiber grating sensing signal and the electro-optical conversion signal are combined, split, and directional controlled on the same single-mode optical fiber in the optical fiber compartment (10). The wellhead fiber optic connection module is connected to the downhole optoelectronic communication module. The downhole optoelectronic communication module uses the fiber optic grating sensor (16) to perform fiber optic sensing of different physical quantities and returns the corresponding fiber optic grating sensing signals to the ground signal demodulation module along the single-mode fiber. It also collects, encodes, and performs electro-optic conversion on the electrical signals of the downhole optoelectronic communication module to form an uplink electro-optic conversion signal.

2. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 1, characterized in that, The ground signal demodulation module includes an optical fiber sensing demodulation component (1), an optical amplifier (2), a first optical circulator (3), a communication modem (4), a second optical circulator (5), and a wavelength division multiplexer (6), wherein, The fiber optic sensing demodulation component (1) is connected to one end of the optical amplifier (2) and the third end of the first optical circulator (3), respectively. The other end of the optical amplifier (2) is connected to the first end of the first optical circulator (3). The second end of the first optical circulator (3) is connected to one end of the wavelength division multiplexer (6) and the second end of the second optical circulator (5), respectively. The first and third ends of the second optical circulator (5) are both connected to the communication modem (4). The communication modem (4) is also connected to the downhole optoelectronic communication module.

3. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 2, characterized in that, The wellhead fiber optic connection module includes a smooth ring (7), a winding machine (8), and a photoelectric wet connector (9) connected in sequence. One end of the smooth ring (7) is connected to the other end of the wavelength division multiplexer (6), and one end of the photoelectric wet connector (9) is connected to the downhole photoelectric communication module.

4. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 3, characterized in that, The downhole optoelectronic communication module includes an optical fiber housing (10), an optical coupler (11), a photodetector (12), a communication demodulator (13), an acousto-optic modulator (14), an optical isolator (15), and a fiber Bragg grating sensor (16), wherein, The fiber optic cable compartment (10) is connected to one end of the optoelectronic wet connector (9) and the first port of the optical coupler (11). The second port of the optical coupler (11) is connected to the communication demodulator (13) through the photodetector (12). The other end of the communication demodulator (13) is connected to the communication modem (4). The third port of the optical coupler (11) is connected to the first end of the acousto-optic modulator (14). The second end of the acousto-optic modulator (14) is connected to the communication modem (4). The third end of the acousto-optic modulator (14) is connected to one end of the optical isolator (15). The other end of the optical isolator (15) is connected to the fourth port of the optical coupler (11) through the fiber optic grating sensor (16).

5. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 4, characterized in that, The splitting ratio between the second, third and fourth ports of the optical coupler (11) is 20:40:

20.

6. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 4, characterized in that, The fiber optic grating sensing signal is transmitted in the C-band, and the electro-optic conversion signal converted by the acousto-optic modulator (14) is transmitted in the O-band or L-band. The fiber optic grating sensing signal and the electro-optic conversion signal are transmitted separately and in parallel in the same single-mode optical fiber through the wavelength division multiplexer (6). The electrical sensor is installed in the fiber optic parameter short section downhole.

7. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 6, characterized in that, The fiber optic grating sensor (16) is installed in the fiber optic parameter short section downhole and connected to the single-mode fiber through the optical coupler (11). The fiber optic grating sensor (16) is used to sense various physical quantities during drilling and return the wavelength shift caused by the physical quantities to the ground through the single-mode fiber for demodulation by the fiber optic grating sensing demodulation component.

8. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 6, characterized in that, The fiber optic sensor (16) includes multiple fiber optic gratings distributed along the axial or circumferential direction of the downhole fiber optic parameter short section. The multiple fiber optic gratings are used to measure one or more physical quantities among downhole temperature, triaxial acceleration, drilling pressure, and torque.

9. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 6, characterized in that, The optical isolator (15) is disposed between the acousto-optic modulator (14) and the optical isolator (15), and the optical isolator (15) is used to isolate the fiber optic grating sensor (16) for unidirectional transmission.

10. The fiber optic sensing integrated system for photoelectric information transmission in logging while drilling as described in claim 4, characterized in that, The communication demodulator (13) is used to receive the downlink control command and to encode and manage the uplink electro-optical conversion signal. The encoding and management includes time division multiplexing or code division multiplexing of the sampling data of different electrical sensors.

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