Underground television signal telemetry system and method based on optical fiber

Abstract

The invention discloses an underground television signal telemetry system and method based on optical fibers. The system comprises an underground measurement and control device, an oil connection transmission device and a ground monitoring device. Wherein the oil connection transmission device is used for controlling the lowering depth of the underground measurement and control device in a well and providing an optical signal transmission channel and a power supply channel for the underground measurement and control device and the ground monitoring device; the underground measurement and control device is used for collecting and processing underground comprehensive data in real time and adjusting the working state according to a control instruction; and the ground monitoring device is used for displaying the underground comprehensive data in real time, acquiring a control instruction of a user, and sending the control instruction to the underground measurement and control device through a downlink optical signal to realize full-duplex communication with the underground measurement and control device. Full-duplex communication between the underground and the ground is achieved through the optical fiber, an operator can obtain the underground condition on the ground in real time and give a real-time control instruction, the problem of electromagnetic interference of data transmission in a deep well is solved, and the real-time feedback performance of the system is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of underground signal transmission, and in particular to an underground television signal remote transmission system and method based on optical fiber. Background Art

[0002] Downhole television is a technology that uses video to directly monitor and evaluate the internal conditions of oil and gas wells. It is mainly used to check the corrosion and scaling of downhole casing, monitor the rupture and dislocation of downhole casing, check the quality of perforation, accurately find water and leaks, and intuitively understand the status of fallen objects in the well.

[0003] At present, the mainstream downhole TV technologies in China are Hawkeye downhole TV and VideoLog downhole TV. They have a common imaging process, and the main difference lies in the channel and coding technology. Hawkeye downhole TV system can operate in high temperature and high pressure environment, with an operating temperature range of 120℃ to 176℃, a working time of up to 4h, a maximum working depth of 25000ft (about 7600m), and a pressure bearing capacity of 12000psi (about 82.7MPa). The system uses single-core or multi-core cables to transmit signals. The downhole video signal is first stored in the downhole equipment and then transmitted to the ground. Therefore, it is subject to certain restrictions in operations with high real-time requirements. VideoLog downhole TV uses a seven-core cable as a data cable and power supply line. It is designed to have a transmission distance of up to 7000m, a temperature resistance of 125℃, a pressure resistance of 35MPa, a transmission rate of up to 2MB / s, and adjustable resolution performance. In addition, the downhole instrument of the VideoLog downhole TV system has completed the forward / side-view array design, so that the well wall and the direction of the instrument can be observed at the same time when the instrument is downhole.

[0004] However, in the era of deep or ultra-deep well exploration and development, it is obviously uneconomical to use cables as data cables and power cables due to the weight of the cables themselves. At the same time, considering the transmission of alternating signals, the self-generated or mutually induced impedance between the conductors and the cable armor or between the conductors in single-core or multi-core cables will degrade the signal and cause signal delay. In addition, armored cables are easily affected by electromagnetic interference from the formation, and the transmission bandwidth is difficult to maintain, which is not conducive to the transmission of multiple signals underground and does not meet the multi-signal monitoring scenarios of complex well conditions.

[0005] Therefore, the present invention proposes an optical fiber-based downhole television signal remote transmission system and method, which can be applied to multi-signal monitoring scenarios of complex well conditions and can transmit downhole television signals at high speed and safely. Summary of the invention

[0006] In view of this, the present invention provides an optical fiber-based downhole television signal remote transmission system and method to solve the technical problems in the current downhole television technology, that is, due to the use of single-core or multi-core cables to transmit downhole television signals, there is electromagnetic interference and signal degradation, and the transmission bandwidth is difficult to maintain, resulting in the existing technology cannot be used in complex deep well or ultra-deep well detection scenarios.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a downhole television signal remote transmission system based on optical fiber, comprising a downhole measurement and control device, an oil-connected transmission device and a ground monitoring device; the downhole measurement and control device is connected to the downhole end of the oil-connected transmission device, and the ground monitoring device is connected to the ground end of the oil-connected transmission device;

[0009] The oil-connected transmission device includes a mixed optical cable, an oil-connected oil pipe, an injection head and a winch; the injection head is arranged at the wellhead of the oil and gas well; the mixed optical cable is arranged in the oil-connected oil pipe, one end of which is connected to the downhole measurement and control device, and the other end passes through the injection head and is connected to the winch; the oil-connected transmission device is used to control the lowering depth of the downhole measurement and control device in the well, and provides an optical signal transmission channel and a power supply channel for the downhole measurement and control device and the ground monitoring device;

[0010] The downhole measurement and control device is lowered into the oil and gas well through the oil transmission device, and is used to collect and process downhole comprehensive data in real time, select an uplink optical signal with a first wavelength for data transmission, send the processed downhole comprehensive data to the ground monitoring device based on the uplink optical signal, and receive a control instruction sent by the ground monitoring device based on a downlink optical signal with a second wavelength, and adjust the working state according to the control instruction;

[0011] The ground monitoring device is connected to the winch through a hybrid optical cable. It is used to receive comprehensive downhole data through the optical fiber part of the hybrid optical cable, upload it to the host computer for real-time display, and transmit the control commands input by the user to the downhole measurement and control device through the downlink optical signal; it is also used to power the downhole measurement and control device through the conductor part of the hybrid optical cable.

[0012] Further, the downhole measurement and control device includes an image acquisition module, a control module and a photoelectric conversion module connected in sequence, and a power management module connected to the image acquisition module, the control module and the photoelectric conversion module;

[0013] The image acquisition module is used to collect high-definition video image data in real time, perform analog-to-digital conversion and encoding compression processing on the video image data, and transmit the processed video image data to the control module via Ethernet;

[0014] The control module is used to obtain downhole environmental parameters and module working state parameters in real time, and receive video image data sent by the image acquisition module; environmental parameters, module working state parameters and video image data constitute downhole measurement and control comprehensive data; it is also used to transmit downhole measurement and control comprehensive data to the photoelectric conversion module, receive control instructions forwarded by the photoelectric conversion module, and adjust the data acquisition state according to the control instructions;

[0015] The photoelectric conversion module is used to convert the downhole measurement and control integrated data from electrical signals to optical signals, and select an uplink optical signal with a first wavelength, and transmit the downhole measurement and control integrated data to the surface monitoring device based on the uplink optical signal; it is also used to receive a control instruction sent by the surface monitoring device, convert the control instruction from an optical signal to an electrical signal, and then forward it to the control module;

[0016] The power management module has its own power supply, which is connected to the mixed optical cable. It is used to receive external power provided by the ground monitoring device and transmitted through the mixed optical cable, distribute the external power with its own power supply, and provide power supply for the image acquisition module, control module and photoelectric conversion module.

[0017] Furthermore, the image acquisition module includes: a data acquisition unit, a data processing unit, an Ethernet unit and a storage unit;

[0018] The data acquisition unit is used to collect high-definition video and image data underground;

[0019] The data processing unit is used to perform analog-to-digital conversion and encoding compression on high-definition video and image data to obtain a video data stream, and divide the video data stream into two paths, the first path is sent to the Ethernet unit, and the second path is sent to the storage unit;

[0020] The Ethernet unit is used to transmit the first video stream data to the control module;

[0021] The storage unit is used to store the second video stream data locally.

[0022] Furthermore, the control module includes a master controller, a slave controller, a measurement and control instrument and an interface module;

[0023] The main controller is used to receive the control instruction forwarded by the photoelectric conversion module, and send the acquisition execution instruction to the slave controller and the image acquisition module according to the control instruction;

[0024] The slave controller is used to control the measurement and control instrument to monitor the downhole environmental parameters and instrument status according to the acquisition execution instruction, and to control the light source of the image acquisition module;

[0025] The measurement and control instrument is used to collect the underground environmental parameters and its own working status parameters;

[0026] The interface module is used to provide communication lines for the main controller and the slave controller, the slave controller and the measurement and control instrument, and the slave controller and the image acquisition module to realize underground multi-parameter measurement and dimming control.

[0027] Furthermore, the photoelectric conversion module includes an optical signal transceiver module, an optical modulation module and an optical decoding module;

[0028] The optical signal transceiver module includes a wavelength selector and a bidirectional optical component, which is used to perform wavelength selection and signal separation on the uplink optical signal and the downlink optical signal to achieve full-duplex communication under a single optical fiber;

[0029] The optical modulation module is used to convert electrical signals into optical signals to achieve optical signal modulation;

[0030] The optical decoding module is used to receive the optical signal and demodulate it into an electrical signal.

[0031] Furthermore, the current transmission mode between the downhole measurement and control device and the ground monitoring device includes a unipolar current mode and a bipolar current mode.

[0032] Furthermore, when the downhole measurement and control device and the ground monitoring device adopt a unipolar current mode, the mixed optical cable includes, from the outside to the inside, a composite armor layer, an alloy cladding, an insulation layer, a conductor, a metal tube and an optical fiber; wherein the conductor has a low DC resistance and is laid on the metal tube at a preset laying angle.

[0033] Furthermore, when the downhole measurement and control device and the ground monitoring device adopt a bipolar current mode, the mixed optical cable includes a composite armor layer, an insulation layer, an outer conductor, an insulation layer, an inner conductor, a metal tube and an optical fiber from the outside to the inside.

[0034] On the other hand, the present invention further provides a method for remote transmission of underground television signals based on optical fiber, which is implemented by using the underground television signal remote transmission system based on optical fiber described in any of the above schemes, comprising:

[0035] According to the prior information of the oil and gas well to be tested, the downhole measurement and control device is lowered into the well through the oil transmission device;

[0036] Collecting downhole comprehensive data in real time through the downhole measurement and control device, and sending it to the surface monitoring device based on the selected uplink optical signal;

[0037] The downhole comprehensive data is received through the ground monitoring device, the downhole comprehensive data is transmitted to the upper computer for real-time display, and the user's control command is obtained, and the control command is sent to the downhole measurement and control device through the downlink optical signal;

[0038] The downhole measurement and control device adjusts the working state after receiving the control instruction and continues to collect and feedback downhole data.

[0039] Furthermore, the downhole measurement and control device is lowered into the well through the oil transmission device, and further includes:

[0040] The pulse signals generated during the rotation of the winch of the oil transmission device are recorded, and the actual lowering depth is determined according to the number and phase of the pulse signals.

[0041] Compared with the prior art, the optical fiber-based underground television signal remote transmission system of the present invention has the following advantages:

[0042] (1) This system uses hybrid optical cables as the channel and conductive wire of the underground television. The hybrid optical cable combines the functions of optical fiber and power transmission, which simplifies the complexity of separately laying cables and optical fibers in traditional underground measurement and control systems, and reduces the difficulty of underground wiring and the workload of maintenance. It fully utilizes the advantages of wide bandwidth, high reliability and low loss of optical fiber communication, avoids the delay effect of the self-generated impedance of the cable under the alternating signal, and realizes real-time transmission. It is suitable for underground television signal transmission in scenarios such as long-distance deep wells or ultra-deep wells, ensuring that real-time communication between the underground and the ground is not limited by distance. It can transmit data over long distances under high temperature, high pressure and corrosive environments, and can resist breaking.

[0043] (2) The downhole measurement and control device collects and processes the comprehensive data of the downhole environment and equipment in real time, selects the uplink optical signal with the first wavelength for data transmission, effectively avoids interference between different signals, and improves the efficiency and accuracy of data transmission. The solution of using different wavelengths for uplink and downlink signals enables the ground equipment and downhole instruments to achieve full-duplex communication on the same optical fiber, making the adjustment and data transmission of downhole equipment more flexible and efficient. The ground monitoring device can send control instructions to the downhole measurement and control device in real time so that the downhole equipment can adjust the working status and ensure the safety and efficiency of downhole operations.

[0044] (3) Through real-time feedback from ground monitoring devices, ground operators can monitor changes in the underground environment in real time and promptly identify potential risks and safety hazards (such as changes in pressure, temperature, gas concentration, etc.), so as to respond in a timely manner and reduce the risk of accidents.

[0045] In summary, this system provides an efficient, reliable and stable underground data transmission system, especially in long-term and deep underground operations, which not only solves the problem of electromagnetic interference, but also improves data transmission efficiency and enhances the real-time feedback capability of the system. Full-duplex communication, precise positioning, simplified wiring and integrated design make the system more efficient and safer to use in complex underground environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1A schematic diagram of the structure of an optical fiber-based underground television signal remote transmission system provided by the present invention;

[0047] Figure 2 A schematic diagram of the structure of the downhole measurement and control device provided by the present invention;

[0048] Figure 3 A structural schematic diagram of the image acquisition module provided by the present invention;

[0049] Figure 4 A schematic diagram of the structure of a control module provided by the present invention;

[0050] Figure 5 A schematic diagram of the optical signal modulation process provided by the present invention;

[0051] Figure 6 A schematic diagram of the optical signal demodulation process provided by the present invention;

[0052] Figure 7 A schematic diagram of the structure of the ground monitoring device provided by the present invention;

[0053] FIG8( a ) is a schematic diagram of the structure of a hybrid optical cable used in a unipolar current case provided by the present invention;

[0054] FIG8( b ) is a schematic diagram of the structure of a hybrid optical cable used in a bipolar current case provided by the present invention;

[0055] Fig. 9 A practical application diagram of the optical fiber-based underground television signal remote transmission system provided by the present invention;

[0056] In the figure, 1-downhole measurement and control subsystem, 2-high-definition camera device, 3-video processing module, 4-slave controller, 5-master controller, 6-photoelectric conversion and modulation module, 7-first bidirectional optical component, 8-power management component, 9-mixed optical cable, 10-oil-connected oil pipe, 11-injection head, 12-winch, 13-motor, 14-ground monitoring subsystem, 15-second bidirectional optical component, 16-photoelectric module, 17-decoding and encoding module, 18-data processor, 19-host computer, 20-host computer interface, 21-oil and gas well, 22-depth wheel, 23-photoelectric encoder. DETAILED DESCRIPTION

[0057] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0058] See also Figure 1, this embodiment provides a downhole television signal remote transmission system 100 based on optical fiber, including a downhole measurement and control device 101, an oil transmission device 102 and a ground monitoring device 103;

[0059] The downhole measurement and control device 101 is connected to the downhole end of the oil transmission device 102, and the surface monitoring device 103 is connected to the surface end of the oil transmission device 102;

[0060] The oil-connected transmission device 102 includes a mixed optical cable, an oil-connected oil pipe, an injection head and a winch; the injection head is arranged at the wellhead of the oil and gas well; the mixed optical cable is arranged in the oil-connected oil pipe, one end of which is connected to the downhole measurement and control device, and the other end passes through the injection head and is connected to the winch; the oil-connected transmission device 102 is used to control the lowering depth of the downhole measurement and control device 101 in the well, and provides an optical signal transmission channel and a power supply channel for the downhole measurement and control device 101 and the ground monitoring device 103;

[0061] The downhole measurement and control device 101 is lowered into the oil and gas well through the oil transmission device 102, and is used to collect downhole comprehensive data in real time, process the downhole comprehensive data, select an uplink optical signal with a first wavelength for data transmission, send the processed downhole comprehensive data to the surface monitoring device 103 based on the uplink optical signal, and receive a control instruction sent by the surface monitoring device 103 based on a downlink optical signal with a second wavelength, and adjust the working state according to the control instruction;

[0062] The ground monitoring device 103 is connected to the winch through a hybrid optical cable, and is used to receive the downhole comprehensive data through the optical fiber part in the hybrid optical cable, and upload it to the host computer for real-time display, and transmit the control instructions input by the user to the downhole measurement and control device 101 through the downlink optical signal; it is also used to power the downhole measurement and control device 101 through the conductor part in the hybrid optical cable.

[0063] In the optical fiber-based downhole television signal teletransmission system provided in this embodiment, the ground monitoring device is connected to the downhole measurement and control device through a mixed optical cable, and different wavelengths of the uplink signal and the downlink signal are used during the communication process to achieve full-duplex communication between the ground and the downhole. The ground monitoring device is connected to the corresponding host computer, and the uplink signal can be displayed in real time on the host computer to achieve human-computer interaction. The mixed optical cable has the advantages of anti-breaking, light weight, high temperature and high pressure resistance, and corrosion resistance. The downhole measurement and control device is lowered into the well through the mixed optical cable, and the downhole measurement and control device obtains real-time image information of the downhole conditions and parameters such as downhole temperature and pressure, which are transmitted up after compression encoding and displayed on the host computer of the ground monitoring device. The operator can adjust the monitoring status of the downhole instrument in real time on the host computer interface according to the uploaded information to obtain clearer images and data.

[0064] This system can solve the problem that cable underground signal remote transmission is not conducive to deep wells due to its own weight and large size. At the same time, it can solve the problem that the transmission signal bandwidth cannot meet the growing demand for underground multi-signal transmission due to electromagnetic interference and self-induced impedance of the cable. By using optical cable as the channel, the signal delay problem caused by cable impedance problem is eliminated, and real-time signal transmission is realized.

[0065] As a preferred embodiment, Figure 2 As shown, the downhole measurement and control device 101 includes an image acquisition module 1011, a control module 1012 and a photoelectric conversion module 1013 connected in sequence, and a power management module 1014 connected to the image acquisition module 1011, the control module 1012 and the photoelectric conversion module 1013;

[0066] The image acquisition module 1011 is used to collect high-definition video image data in real time, perform analog-to-digital conversion and encoding compression processing on the video image data, and transmit the processed video image data to the control module 1012 via Ethernet;

[0067] The control module 1012 is used to obtain downhole environmental parameters and module working state parameters in real time, and receive the video image data sent by the image acquisition module 1011; the environmental parameters, module working state parameters and video image data constitute downhole measurement and control comprehensive data; and is also used to transmit the downhole measurement and control comprehensive data to the photoelectric conversion module 1013, receive the control instructions forwarded by the photoelectric conversion module 1013, and adjust the data acquisition state according to the control instructions;

[0068] The photoelectric conversion module 1013 is used to convert the downhole measurement and control integrated data from an electrical signal into an optical signal, and select an uplink optical signal with a first wavelength, and transmit the downhole measurement and control integrated data to the surface monitoring device 103 based on the uplink optical signal; it is also used to receive a control instruction sent by the surface monitoring device 103, convert the control instruction from an optical signal into an electrical signal, and then forward it to the control module 1012;

[0069] The power management module 1014 has its own power supply (dry battery) and is connected to the mixed optical cable. It is used to receive external power provided by the ground monitoring device and transmitted through the mixed optical cable, distribute the external power and its own power supply, and provide power supply for the image acquisition module 1011, the control module 1012 and the photoelectric conversion module 1013.

[0070] In the above scheme, the power management module improves the overall working time of the downhole measurement and control device by managing the power provided by the hybrid optical cable and the battery power carried by itself. Under the management of the power management module, the image acquisition module obtains real-time image information of the downhole, which is processed and regulated by the control module, and then converted into optical signals by the photoelectric conversion module, and transmitted to the ground through the optical fiber in the hybrid optical cable.

[0071] As a preferred embodiment, Figure 3 As shown, the image acquisition module includes: a data acquisition unit, a data processing unit, an Ethernet unit and a storage unit;

[0072] The data acquisition unit is used to collect high-definition video and image data underground;

[0073] The data processing unit is used to perform analog-to-digital conversion and encoding compression on the high-definition video and image data to obtain a video data stream, and divide the video data stream into two paths, a first path is sent to the Ethernet unit, and a second path is sent to the storage unit;

[0074] The Ethernet unit is used to transmit the first video stream data to the control module;

[0075] The storage unit is used to store the second video stream data locally.

[0076] Specifically, the data acquisition unit and the data processing unit use the MIPI interface, which is designed with high bandwidth capabilities, can support fast data transmission, and has the advantage of low power consumption, which can extend the single use time of the device. The data processing unit and the Ethernet unit use the MII interface, which transmits data, control and management information through a set of signal lines, and supports high-speed data exchange between the Ethernet physical layer and the media access control layer of the device.

[0077] In some embodiments, the data acquisition unit uses a high-definition camera to collect high-definition video image data underground. The general video signal bandwidth is 6MHz. If it is not compressed, a data transmission rate of 96Mbps is required, so the data needs to be compressed and encoded during the transmission process. The encoding scheme used by the high-definition camera is H.264, whose main feature is that it can provide high-quality video images at a low bit rate.

[0078] As a preferred embodiment, Figure 4 As shown, the control module includes a master controller, a slave controller, a measurement and control instrument and an interface module;

[0079] The main controller is used to receive the control instruction forwarded by the photoelectric conversion module, and send the acquisition execution instruction to the slave controller and the image acquisition module according to the control instruction;

[0080] The slave controller is used to control the measurement and control instrument to monitor the downhole environmental parameters and instrument status according to the acquisition execution instruction, and to control the light source of the image acquisition module;

[0081] The measurement and control instrument is used to collect the underground environmental parameters and its own working status parameters;

[0082] The interface module is used to provide communication lines for the master controller and the slave controller, the slave controller and the measurement and control instrument, and the slave controller and the image acquisition module to realize underground multi-parameter measurement and dimming control.

[0083] In some embodiments, the measurement and control instrument detects the temperature, pressure and other parameters of the well, and uses a controllable cold light LED light source to adjust the light source of the data acquisition unit, while reducing the impact of the heat generated by the light source on the circuit board of the well instrument, and adjusting the video clarity by adjusting the brightness of the light source in real time. The measurement and control instrument also has other measurement and control modules with extended functions, and a laser for determining the well type is also installed in the module.

[0084] In some embodiments, the main controller can select MCU, ARM, DSP, CPLD, FPGA, etc. according to the circuit budget. In principle, the hardware part of the downhole system needs to be simplified as much as possible.

[0085] The interface module uses RS485 bus and CAN bus to meet the connection requirements of different instruments. The main controller establishes communication with the slave through the expansion bus interface to achieve multi-parameter measurement and dimming control.

[0086] As a preferred embodiment, the photoelectric conversion module includes an optical signal transceiver module, an optical modulation module and an optical decoding module;

[0087] The optical signal transceiver module includes a wavelength selector and a bidirectional optical component, which is used to perform wavelength selection and signal separation on the uplink optical signal and the downlink optical signal to achieve full-duplex communication under a single optical fiber;

[0088] The optical modulation module is used to convert electrical signals into optical signals to achieve optical signal modulation;

[0089] The optical decoding module is used to receive the optical signal and demodulate it into an electrical signal.

[0090] In a specific embodiment, to achieve full-duplex communication, the optical signal transceiver module selects light waves with wavelengths of 1310nm and 1550nm as the downhole instrument sending signal wavelength and receiving signal wavelength respectively. The module uses a Bragg grating (FBG) to separate the two wavelength signals. The Bragg grating, as a wavelength selector, can be integrated in a bidirectional optical component for optical transmission and reception to achieve full-duplex communication using only one optical fiber.

[0091] As a specific embodiment, when using optical fiber as a channel, the signal needs to be modulated. The modulation methods of the optical modulation module include amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), quadrature amplitude modulation (QAM), polarization modulation (POIM), orthogonal frequency division multiplexing (OFDM) and direct intensity modulation. In practice, it is necessary to select appropriate instruments and circuits according to the downhole data to be measured and controlled, so as to determine the optical modulation method.

[0092] It should be noted that if Figure 5 As shown in the figure, during the uplink transmission process, the digital signal is transmitted from the main controller to the high-speed switch, and the electrical signal is modulated into a signal of a specific wavelength (1310nm) through the laser, and then through the wavelength selection of the grating, it is transmitted up to the ground through the optical fiber. Here, the reference current source and the voltage-controlled current source need to be adapted to the laser, which can be an LED or a LD.

[0093] like Figure 6 As shown, during the downlink transmission process, the control signal of the ground with a specific wavelength (1550nm) is selected by the optical fiber and the Bragg grating, and converted into a digital signal through the conversion circuit. After being decoded, it is received by the main controller to adjust various parameters of the downhole instrument.

[0094] As a specific example, Figure 7 As shown, the ground monitoring device is also integrated with a bidirectional optical component, which is connected to the optoelectronic module, which is connected to the decoding and encoding module. The control module of the ground monitoring device is connected to the PC through the TCP / IP interface. The PC is equipped with a host computer interface that matches the downhole high-definition camera device, and the human-computer interaction with the system is carried out through this interface. The ground monitoring device is used to receive the video signal and parameter feedback from the downhole, and make timely adjustments according to the downhole parameter detection signal. The monitoring signal is transmitted to the downhole instrument through the optical fiber.

[0095] Through the real-time display of downhole parameters and videos on the upper computer, the brightness of the light source is increased when there is turbid liquid or more particles in the well, and vice versa for clearer liquids, to prevent the reflection of bright light from affecting the video quality, keep the downhole system at a uniform speed, and when approaching the target, the video on the upper computer interface is clearer through the automatic focus function of the camera device. The downhole measurement and control device can keep its internal temperature within the normal range through thermoelectric cooling technology. Among them, the pressure measurement and control instrument used to monitor the downhole pressure must be well packaged on the premise that the downhole measurement and control device is well packaged, and the upper computer on the ground needs to save the received data regularly.

[0096] Based on real-time video information, the corrosion and scaling conditions of the downhole casing, as well as the rupture and misalignment of the downhole casing can be checked to assist in determining the service life of the casing; the fracturing effect can be intuitively determined based on the shape and size of the perforation openings before and after fracturing; while the camera device is being lowered at a uniform speed, the holes and cracks that are leaking water or sand can be observed in real time on the upper computer interface.

[0097] In practice, downhole television is more used in the detection of fallen objects underground: the shape of the fallen objects can be clearly seen on the video interface, and the location of the fallen objects can be determined based on the distance the oil is lowered, so as to help operators decide what plan to use for the salvage of fallen objects.

[0098] As a specific embodiment, in order to receive downhole signals at high speed, the ground monitoring device uses the high-speed parallel interface of FPGA, and other functions such as power management, digital-to-analog conversion, data transmission and filtering are completed by MCU (STM32 or DPS). The ground part uses 1550nm light for transmission and 1310nm light for reception, and wavelength screening is completed by bidirectional optical components.

[0099] In some embodiments, after the downhole signal is decoded and restored through digital-to-analog conversion in the ground monitoring device, it is read into the host computer program through the network port. At the same time, the host computer interface development must match the downhole high-definition camera and be developed according to the corresponding SDK. The host computer interface is combined with the OpenCV library, and the data is filtered and denoised, contrast enhanced, and resolution adjusted. The interface clearly displays the downhole conditions, and then the window is selected to extract the interface of interest. On the interface, according to the uploaded downhole temperature and pressure and other state parameters, the light source brightness adjustment, camera position adjustment, data saving and other buttons are set on the operation button bar to improve the convenience of human-computer interaction.

[0100] As a preferred embodiment, the current transmission mode between the downhole measurement and control device and the ground monitoring device includes a unipolar current mode and a bipolar current mode.

[0101] Unipolar current refers to the current flowing in one direction only through one conductor. In order to reduce the energy loss when the current flows inside the cable, low-resistance conductor materials can be selected to ensure the current transmission efficiency. Bipolar current refers to the current passing through two conductors, with positive and negative voltages on each conductor. It is usually used in more complex power transmission systems. This configuration is conducive to balancing the current flow and reducing the interference and electromagnetic influence of the system.

[0102] As a preferred embodiment, as shown in Figure 8(a), when the downhole measurement and control device and the ground monitoring device adopt a unipolar current mode, the mixed optical cable includes, from the outside to the inside, a composite armor layer, an alloy cladding, an insulation layer, a conductor, a metal tube and an optical fiber; wherein the conductor has a low DC resistance and is laid on the metal tube at a preset laying angle.

[0103] The outer layer of the conductor has an elastic insulator layer, usually made of elastic fluoride, which can both insulate and increase the maximum tensile strength of the optical cable. The sub-outer layer of the optical cable is equipped with an alloy sheath, which is matched with the outermost composite armor to provide mechanical strength and chemical compatibility with harsh fluids. They can adapt to the high temperature and high pressure environment underground. Such an optical cable structure can withstand complex environments such as high temperature and high pressure underground.

[0104] As a preferred embodiment, as shown in Figure 8(b), when the downhole measurement and control device and the ground monitoring device adopt a bipolar current mode, the mixed optical cable includes a composite armor layer, an insulation layer, an outer conductor, an insulation layer, an inner conductor, a metal tube and an optical fiber from the outside to the inside.

[0105] As a specific example, Fig. 9 As shown, Fig. 9 A schematic diagram of the specific application scenario of this system is shown. Fig. 9 In the present invention, the optical fiber-based downhole television signal remote transmission system includes a downhole measurement and control subsystem 1 and a ground monitoring subsystem 14. The downhole measurement and control system is lowered into an oil and gas well 21 through an oil-connecting oil pipe 10. The oil and gas well 21 can be a vertical well, an inclined well or a horizontal well. It is only necessary to configure corresponding motion auxiliary devices such as a stabilizer at the downhole end of the oil-connecting oil pipe 10 to adjust it according to the shape of different wells.

[0106] The oil connecting pipe 10 is provided with a mixed optical cable 9 , and its two ends are connected to the downhole measurement and control subsystem 1 and the winch 12 .

[0107] The downhole measurement and control subsystem 1 is equipped with a high-definition camera 2, and the corresponding video processing module 3 includes a light source, a video processor and a storage device corresponding to the high-definition camera 2. The slave controller 4 is used to control other downhole measurement and control instruments. The main controller 5 is the hub of downhole data. The photoelectric conversion and modulation module 6 and the first bidirectional optical component 7 are used for photoelectric conversion, encoding and decoding, and wavelength selection. The mixed optical cable 9 is connected to the power management component 8.

[0108] The injection head 11 of the oil-connected oil pipe 10 is arranged at the wellhead, and the mixed optical cable 9 passes through the injection head 11 and is connected to the winch 12 on the ground. The winch 12 is equipped with a depth wheel 22 and a photoelectric encoder 23. The motor 13 in the winch 12 can control the lowering depth of the oil-connected oil pipe 10.

[0109] The ground monitoring subsystem 14 is connected to the winch 12 through a matching optical fiber. The ground monitoring subsystem 14 also integrates a second bidirectional optical component 15, which is connected to the optoelectronic module 16, and the optoelectronic module 16 is connected to the decoding and encoding module 17. The data processor 18 of the ground monitoring subsystem 14 is connected to the host computer 19 through a TCP / IP interface. The host computer 19 is equipped with a host computer interface 20 that matches the downhole high-definition camera device, and human-computer interaction is achieved through this interface.

[0110] The embodiment of the present invention further provides a method for remote transmission of underground television signals based on optical fiber, which is implemented by using the underground television signal remote transmission system based on optical fiber described in any of the above technical solutions, and includes:

[0111] According to the prior information of the oil and gas well to be tested, it is lowered into the well through the mixed optical cable and oil transmission device;

[0112] Collecting downhole comprehensive data in real time through the downhole measurement and control device, and sending it to the surface monitoring device based on the selected uplink optical signal;

[0113] The downhole comprehensive data is received through the ground monitoring device, the downhole comprehensive data is transmitted to the upper computer for real-time display, and the user's control command is obtained, and the control command is sent to the downhole measurement and control device through the downlink optical signal;

[0114] The downhole measurement and control device adjusts the working state after receiving the control instruction and continues to collect and feedback downhole data.

[0115] The method of this embodiment realizes full-duplex communication between downhole instruments and ground devices through optical fibers. The downhole instruments are lowered into the well for detection through oil connection. A host computer is installed in the PC, which is connected to the ground monitoring device through a TCP / IP protocol interface. The signal line connecting the ground monitoring device and the oil connection winch is an optical fiber matched with the optical cable. The downhole conditions can be observed in real time by the host computer and adjusted.

[0116] In a specific embodiment, after the well is washed, the downhole instrument can be lowered into the well through the oil connection for video acquisition. The optical cable is placed in the oil connection, the downhole measurement and control system is connected to the downhole end of the oil connection, the ground monitoring system is connected to the winch through the optical cable, and the downhole measurement and control system is lowered by the motor on the winch. The depth of the downhole measurement and control system is determined according to the length of the oil connection. The power supply of the downhole measurement and control system can be supplied by the conductor in the optical cable or the battery carried by itself, which can ensure that the downhole system can run for a long time in the well. During the lowering process, according to the video interface displayed on the upper computer software and the uplink downhole parameters, the brightness of the light source, the downhole system lowering depth and other operations are adjusted on the upper computer, and the downhole target is gradually approached to obtain a clear video interface. While the video signal is stored in the well, the uplink video signal will be stored on the upper PC, which can be compared with the downhole data after the downhole instrument is taken out, as a basis for system improvement. Finally, the uplink video information is used to judge the downhole situation to make decisions on the corresponding downhole operations.

[0117] The optical fiber-based underground television signal remote transmission system and method proposed in the present invention can solve the problem that cable underground signal remote transmission is not conducive to deep wells due to its own weight and large size. At the same time, it solves the problem that the transmission signal bandwidth cannot meet the growing demand for underground multi-signal transmission due to electromagnetic interference and self-induced impedance of the cable. In addition, since the optical cable is used as the channel, the signal delay problem caused by the cable impedance problem is eliminated, and real-time signal transmission is realized.

[0118] In some embodiments, after checking whether the system is complete, the system can be debugged at the wellhead, including whether the host computer can work normally, whether the ground measurement and control system, the oil-connected winch and its motor, and the downhole measurement and control system can respond to debugging.

[0119] After the well is washed, the downhole measurement and control system is lowered into the well by an oil-connected winch, the light source is turned on, and the camera device collects real-time image information in the well.

[0120] Since the prior data of the observation well may have size errors, in order to avoid collisions and other situations that may occur when lowering the downhole measurement and control device according to the size of the existing oil and gas well, as a preferred embodiment, during the actual lowering of the downhole measurement and control device, the lowering depth also needs to be monitored. Specifically, the depth of the downhole measurement and control system can be measured by the depth wheel on the winch, and converted into an optical signal by a photoelectric encoder and uploaded to the ground monitoring system.

[0121] When the winch rotates, the depth wheel will generate A and B two-phase counting pulses. The number of pulses records the depth, and the pulse phase relationship indicates the direction. The A and B two-phase signals are two pulse signals with a phase difference of 90°. If the A phase leads the B phase by 90° when lowering, and vice versa when lifting, the depth calculation formula is:

[0122]

[0123] Among them, h represents the depth, that is, the running length of the hybrid optical cable, l represents the circumference of the depth wheel, k represents the total number of pulses output by the depth wheel during the movement of the optical cable, and k0 is the number of pulses output when the depth wheel rotates one circle during the movement of the cable.

[0124] In some embodiments, in order to determine the specific shape of the oil and gas well (vertical well, inclined well or horizontal well), a laser for measuring direction is installed on other control modules of the slave controller of the downhole measurement and control system. When the downhole system is lowered, when the angle α between the laser beam and the wellbore is 0°, it is determined to be running in the vertical well, and the running length of the optical cable is the lowering depth of the downhole system; when 0°<α<90°, the running depth of this section of the optical cable needs to be converted according to the following formula:

[0125] h1=h0 sinα

[0126] Among them, h1 is the depth of the oil-connected well, and h0 is its running length; when α=90°, the system recognizes this section as a horizontal well, and the oil-connected well running depth is 0.

[0127] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An optical fiber-based underground television signal remote transmission system, characterized in that: It includes a downhole measurement and control device, an oil transmission device and a ground monitoring device; the downhole measurement and control device is connected to the downhole end of the oil transmission device, and the ground monitoring device is connected to the ground end of the oil transmission device; The oil-connected transmission device includes a mixed optical cable, an oil-connected oil pipe, an injection head and a winch; the injection head is arranged at the wellhead of the oil and gas well; the mixed optical cable is arranged in the oil-connected oil pipe, one end of which is connected to the downhole measurement and control device, and the other end passes through the injection head and is connected to the winch; the oil-connected transmission device is used to control the lowering depth of the downhole measurement and control device in the well, and provides an optical signal transmission channel and a power supply channel for the downhole measurement and control device and the ground monitoring device; The downhole measurement and control device is lowered into the oil and gas well through the oil transmission device, and is used to collect and process downhole comprehensive data in real time, select an uplink optical signal with a first wavelength for data transmission, send the processed downhole comprehensive data to the ground monitoring device based on the uplink optical signal, and receive a control instruction sent by the ground monitoring device based on a downlink optical signal with a second wavelength, and adjust the working state according to the control instruction; The ground monitoring device is connected to the winch through a hybrid optical cable. It is used to receive comprehensive downhole data through the optical fiber part of the hybrid optical cable, upload it to the host computer for real-time display, and transmit the control commands input by the user to the downhole measurement and control device through the downlink optical signal; it is also used to power the downhole measurement and control device through the conductor part of the hybrid optical cable.

2. The optical fiber-based underground television signal remote transmission system according to claim 1 is characterized in that: The downhole measurement and control device comprises an image acquisition module, a control module and a photoelectric conversion module connected in sequence, and a power management module connected to the image acquisition module, the control module and the photoelectric conversion module; The image acquisition module is used to collect high-definition video image data in real time, perform analog-to-digital conversion and encoding compression processing on the video image data, and transmit the processed video image data to the control module via Ethernet; The control module is used to obtain downhole environmental parameters and module working state parameters in real time, and receive video image data sent by the image acquisition module; environmental parameters, module working state parameters and video image data constitute downhole measurement and control comprehensive data; it is also used to transmit downhole measurement and control comprehensive data to the photoelectric conversion module, receive control instructions forwarded by the photoelectric conversion module, and adjust the data acquisition state according to the control instructions; The photoelectric conversion module is used to convert the downhole measurement and control integrated data from electrical signals to optical signals, and select an uplink optical signal with a first wavelength, and transmit the downhole measurement and control integrated data to the surface monitoring device based on the uplink optical signal; it is also used to receive a control instruction sent by the surface monitoring device, convert the control instruction from an optical signal to an electrical signal, and then forward it to the control module; The power management module has its own power supply, which is connected to the mixed optical cable. It is used to receive external power provided by the ground monitoring device and transmitted through the mixed optical cable, distribute the external power with its own power supply, and provide power supply for the image acquisition module, control module and photoelectric conversion module.

3. The optical fiber-based underground television signal remote transmission system according to claim 2 is characterized in that: The image acquisition module includes: a data acquisition unit, a data processing unit, an Ethernet unit and a storage unit; The data acquisition unit is used to collect high-definition video and image data underground; The data processing unit is used to perform analog-to-digital conversion and encoding compression on high-definition video and image data to obtain a video data stream, and divide the video data stream into two paths, the first path is sent to the Ethernet unit, and the second path is sent to the storage unit; The Ethernet unit is used to transmit the first video stream data to the control module; The storage unit is used to store the second video stream data locally.

4. The optical fiber-based underground television signal remote transmission system according to claim 2 is characterized in that: The control module includes a main controller, a slave controller, a measurement and control instrument and an interface module; The main controller is used to receive the control instruction forwarded by the photoelectric conversion module, and send the acquisition execution instruction to the slave controller and the image acquisition module according to the control instruction; The slave controller is used to control the measurement and control instrument to monitor the downhole environmental parameters and instrument status according to the acquisition execution instruction, and to control the light source of the image acquisition module; The measurement and control instrument is used to collect the underground environmental parameters and its own working status parameters; The interface module is used to provide communication lines for the main controller and the slave controller, the slave controller and the measurement and control instrument, and the slave controller and the image acquisition module to realize underground multi-parameter measurement and dimming control.

5. The optical fiber-based underground television signal remote transmission system according to claim 2, characterized in that: The photoelectric conversion module includes an optical signal transceiver module, an optical modulation module and an optical decoding module; The optical signal transceiver module includes a wavelength selector and a bidirectional optical component, which is used to perform wavelength selection and signal separation on the uplink optical signal and the downlink optical signal to achieve full-duplex communication under a single optical fiber; The optical modulation module is used to convert electrical signals into optical signals to achieve optical signal modulation; The optical decoding module is used to receive the optical signal and demodulate it into an electrical signal.

6. The optical fiber-based underground television signal remote transmission system according to claim 1, characterized in that: The current transmission mode between the downhole measurement and control device and the ground monitoring device includes a unipolar current mode and a bipolar current mode.

7. The optical fiber-based underground television signal remote transmission system according to claim 6, characterized in that: When the downhole measurement and control device and the ground monitoring device adopt a unipolar current mode, the mixed optical cable includes, from the outside to the inside, a composite armor layer, an alloy cladding, an insulator layer, a conductor, a metal tube and an optical fiber; wherein the conductor has a low DC resistance and is laid on the metal tube at a preset laying angle.

8. The optical fiber-based underground television signal remote transmission system according to claim 6, characterized in that: When the downhole measurement and control device and the ground monitoring device adopt a bipolar current mode, the mixed optical cable includes a composite armor layer, an insulator layer, an outer conductor, an insulator layer, an inner conductor, a metal tube and an optical fiber from the outside to the inside.

9. A method for remote transmission of underground television signals based on optical fiber, characterized in that: The optical fiber-based downhole television signal remote transmission system according to any one of claims 1 to 8 is implemented, comprising: According to the prior information of the oil and gas well to be tested, the downhole measurement and control device is lowered into the well through the oil transmission device; Collecting downhole comprehensive data in real time through the downhole measurement and control device, and sending it to the surface monitoring device based on the selected uplink optical signal; The downhole comprehensive data is received through the ground monitoring device, the downhole comprehensive data is transmitted to the upper computer for real-time display, and the user's control command is obtained, and the control command is sent to the downhole measurement and control device through the downlink optical signal; The downhole measurement and control device adjusts the working state after receiving the control instruction and continues to collect and feedback downhole data.

10. The optical fiber-based underground television signal remote transmission method according to claim 9, characterized in that: The downhole measurement and control device is lowered into the well through an oil transmission device, and further comprises: The pulse signals generated during the rotation of the winch of the oil transmission device are recorded, and the actual lowering depth is determined according to the number and phase of the pulse signals.

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