Outer jacketed cable, outer jacketed cable detection system and method

Abstract

This invention provides an external armored optical cable detection system and method, belonging to the field of petroleum geological exploration. The external armored optical cable detection system includes an electromagnetic excitation module and a magnetic signal detection module. The electromagnetic excitation module includes a ground electrode connected to the ground end of the armored optical cable, used to send a current excitation signal to the armored optical cable. Under the action of the current excitation signal, the armored optical cable generates an alternating magnetic field. The magnetic signal detection module is located inside the casing and is used to detect the alternating magnetic field generated by the armored optical cable to obtain the position information of the armored optical cable. This invention applies an excitation current to the armored optical cable outside the casing. Under the action of the excitation current, the armored optical cable itself generates an alternating magnetic field. The magnetic signal detection module detects the alternating magnetic field generated by the armored cable to determine the position information of the armored optical cable. This invention improves the detection accuracy by increasing the intensity of the electromagnetic signal through the alternating magnetic field generated by the armored optical cable itself.

Description

Technical Field

[0001] This invention relates to the field of petroleum geological exploration technology, specifically to an armored optical cable outside a casing, an external optical cable detection system, an external optical cable detection method, a computer device, and a computer-readable storage medium. Background Technology

[0002] With the continuous advancement of digital transformation in oilfields, intelligent technologies have emerged that use permanent sensors installed downhole to acquire dynamic parameters of the oil and gas production process. Among these technologies, fiber optic sensors, directly deployed outside the casing, can monitor real-time information such as the original formation pressure and noise outside the casing, providing a basis for judging the actual production status of oil and gas wells.

[0003] However, perforation in the well section is an essential oil production process. In cases of blind perforation, optical cables closely attached to the outer wall of the casing are easily damaged, severely limiting the application range of external casing optical cables. For external fiber optic cables, accurate detection and positioning of the fiber, as well as precise fiber-avoiding directional perforation, play a crucial role in ensuring the integrity of the external fiber optic cable.

[0004] For fiber optic cable inspection methods on the outer wall of casing, the available options are very limited. Among them, electromagnetic detection has become the preferred choice due to its high detection efficiency, good penetration, and high safety and reliability. Existing technology uses a DC magnetic orientation tool to detect and identify the armored fiber optic cable on the outer wall of the casing, providing a high-quality perforation well deflection angle for perforation work. This tool uses a motor to drive an eccentric probe to rotate 360° for circumferential detection, and determines the fiber distribution based on the high-quality metal side in the circumferential test data. Obviously, relying on a motor for 360° circumferential measurement requires the tool to be stationary in that position while the motor scans 360° to find the high-quality metal side before proceeding to the next depth measurement. Although the tool can achieve high circumferential resolution through manual control, it also sacrifices its continuous measurement capability, resulting in extremely low work efficiency. Furthermore, the selection interval between adjacent depth points can severely affect the judgment of the fiber distribution path. Existing technologies improve circumferential detection resolution by acquiring multi-directional electromagnetic signals through multi-component detection probes. However, as the number of probes increases, the requirements for instrument space and circuit load also increase, making it difficult to accurately detect weak signals from the outer sheath of the optical cable. Summary of the Invention

[0005] To address the aforementioned technical deficiencies, this invention provides an external armored optical cable, an external armored optical cable detection system, and a method. The external armored optical cable detection system applies an excitation current to the external armored optical cable. Under the influence of the excitation current, the external armored optical cable generates its own alternating magnetic field. A magnetic signal detection module detects the alternating magnetic field generated by the armored cable to determine its location. This invention improves detection accuracy by increasing the intensity of the electromagnetic signal through the alternating magnetic field generated by the armored optical cable itself.

[0006] The first aspect of the present invention provides an armored optical cable outside the casing for use in oil wells, the armored optical cable comprising: an optical fiber unit, a first steel wire rope, a second steel wire rope, and a connecting conductor; The first steel wire rope and the second steel wire rope are disposed on both sides of the optical fiber unit; The first steel wire rope at the underground end of the armored optical cable is connected to the second steel wire rope at the underground end of the armored optical cable via the connecting conductor. When the first and second steel wire ropes at the ground end of the armored optical cable are connected to the ground electrode at the wellhead, the armored optical cable and the ground electrode form a conductive circuit. The ground electrode is used to apply alternating current excitation to the armored optical cable to generate an alternating magnetic field.

[0007] In this embodiment of the invention, the optical fiber unit includes an optical fiber and a sheath steel tube, wherein the sheath steel tube is sleeved on the outside of the optical fiber.

[0008] In this embodiment of the invention, there are multiple sheathing steel pipes, which are successively fitted over the optical fiber, and the diameter of the multiple sheathing steel pipes increases progressively.

[0009] In this embodiment of the invention, the armored optical cable further includes: an outer sheath; The outer sheath is used to encapsulate the optical fiber unit, the first steel wire rope, the second steel wire rope, and the connecting wire.

[0010] A second aspect of the present invention provides an external sheath optical cable detection system for detecting armored optical cables outside the sheath as described above. The system includes an electromagnetic excitation module and a magnetic signal detection module. The electromagnetic excitation module includes: a ground electrode, which is connected to the ground end of the armored optical cable and is used to send a current excitation signal to the armored optical cable; The armored optical cable generates an alternating magnetic field under the action of the current excitation signal; The magnetic signal detection module is located inside the sleeve. The magnetic signal detection module is used to detect the alternating magnetic field generated by the armored optical cable to obtain the position information of the armored optical cable.

[0011] In this embodiment of the invention, the magnetic signal detection module includes: a ring array of magnetic field sensors; The magnetic field sensor ring array is distributed inside the sheath. The magnetic field sensor ring array includes multiple magnetic field sensors arranged in a ring array. All multiple magnetic field sensors detect the alternating magnetic field generated by the armored optical cable to obtain alternating magnetic field information.

[0012] In this embodiment of the invention, the magnetic signal detection module further includes: a circuit unit; The circuit unit is communicatively connected to multiple magnetic field sensors to receive alternating magnetic field information collected by the multiple magnetic field sensors and to determine the position information of the armored optical cable based on the multiple alternating magnetic field information.

[0013] In this embodiment of the invention, the magnetic signal detection module further includes: a remote transmission unit; The remote transmission unit is used to transmit the location information of the armored optical cable determined by the circuit unit to the ground-based data receiving device.

[0014] In this embodiment of the invention, the system further includes: armored logging cable and wellhead surface logging vehicle; One end of the armored logging cable is connected to a magnetic signal detection module, and the other end of the armored logging cable is connected to the wellhead surface logging vehicle; The wellhead surface logging vehicle lowers the magnetic signal detection module into the casing via the armored logging cable.

[0015] In this embodiment of the invention, the data receiving device is mounted on the wellhead surface logging vehicle.

[0016] A third aspect of the present invention provides a method for detecting an external optical cable under a sheath, comprising: The armored optical cable is sent a current excitation signal through the electromagnetic excitation module. The armored optical cable is an armored optical cable with an outer sheath as described above. Armored optical cables generate alternating magnetic fields under the action of current excitation signals; The location information of the armored optical cable is obtained by detecting the alternating magnetic field generated by the armored optical cable using a magnetic signal detection module.

[0017] A fourth aspect of the present invention provides a computer device, comprising: Memory, which stores computer programs; A processor is used to execute the computer program to implement the above-described method for detecting external optical cables under a sheath.

[0018] A fifth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the above-described method for detecting external optical cables under a sheath. The aforementioned external sheath optical cable detection system applies an excitation current to the armored optical cable outside the sheath. Under the action of the excitation current, the armored optical cable outside the sheath generates an alternating magnetic field. The alternating magnetic field generated by the armored optical cable is detected by a magnetic signal detection module to determine the location information of the armored optical cable. This invention improves the detection accuracy by increasing the intensity of the electromagnetic signal through the alternating magnetic field generated by the armored optical cable itself.

[0019] Other features and advantages of the technical solution of the present invention will be described in detail in the following detailed embodiments section. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of the armored optical cable when it deflects according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the armored optical cable outside the sheath provided in an embodiment of the present invention; Figure 3 This is a side view of the armored optical cable outside the sheath provided in an embodiment of the present invention; Figure 4 This is a cross-sectional view of the armored optical cable outside the sheath provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the sheathed external optical cable detection system provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the connection between the armored optical cable and the ground electrode provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the magnetic field sensor ring array provided in an embodiment of the present invention; Figure 8 This is a flowchart of the method for detecting external optical cables provided in an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures 01-Fiber optic cable, 02-First steel wire rope, 03-Second steel wire rope, 04-Sheath steel pipe, 05-Outer sheath, 06-Ground electrode, 07-Magnetic field sensor ring array, 08-Circuit unit, 09-Remote transmission unit, 10-Connecting wire. Detailed Implementation

[0022] To make the technical solutions and advantages of the embodiments of the present invention clearer, the exemplary embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0025] In this invention, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] In the process of realizing this invention, the inventors discovered that with the continuous advancement of digital transformation in oilfields, intelligent technologies have emerged to acquire dynamic parameters of the oil and gas production process by installing permanent sensors downhole. Among these technologies, directly deploying fiber optic sensors outside the casing enables real-time monitoring of information such as the original formation pressure and noise outside the casing, providing a basis for judging the actual production status of oil and gas wells.

[0027] However, perforation in the well section is an essential oil production process. In cases of blind perforation, optical cables closely attached to the outer wall of the casing are easily damaged, severely limiting the application range of external casing optical cables. For external fiber optic cables, accurate detection and positioning of the fiber, as well as precise fiber-avoiding directional perforation, play a crucial role in ensuring the integrity of the external fiber optic cable.

[0028] For fiber optic cable inspection methods on the outer wall of casing, the available options are very limited. Among them, electromagnetic detection has become the preferred choice due to its high detection efficiency, good penetration, and high safety and reliability. Existing technology uses a DC magnetic orientation tool to detect and identify the armored fiber optic cable on the outer wall of the casing, providing a high-quality perforation well deflection angle for perforation work. This tool uses a motor to drive an eccentric probe to rotate 360° for circumferential detection, and determines the fiber distribution based on the high-quality metal side in the circumferential test data. Obviously, relying on a motor for 360° circumferential measurement requires the tool to be stationary in that position while the motor scans 360° to find the high-quality metal side before proceeding to the next depth measurement. Although the tool can achieve high circumferential resolution through manual control, it also sacrifices its continuous measurement capability, resulting in extremely low work efficiency. Furthermore, the selection interval between adjacent depth points can severely affect the judgment of the fiber distribution path. Existing technologies improve circumferential detection resolution by acquiring multi-directional electromagnetic signals through multi-component detection probes. However, as the number of probes increases, the requirements for instrument space and circuit load also increase, making it difficult to accurately detect weak signals from the outer sheath of the optical cable.

[0029] To address the aforementioned problems, this invention provides an external optical cable detection system for detecting armored optical cables outside a casing. The armored optical cable includes: an optical fiber unit, a first steel wire rope, a second steel wire rope, and a connecting conductor. The first and second steel wire ropes are symmetrically arranged on both sides of the optical fiber unit. The connecting conductor is located at the end of the armored optical cable located underground. One end of the connecting conductor is connected to the first steel wire rope, and the other end is connected to the second steel wire rope. The connecting conductor, the first steel wire rope, and the second steel wire rope form a conductive loop. The armored optical cable's ground-side end is connected to a ground electrode, which sends a current excitation signal to the conductive circuit. The system includes an electromagnetic excitation module and a magnetic signal detection module. The electromagnetic excitation module includes a ground electrode connected to the ground end of the armored optical cable, used to send a current excitation signal to the armored optical cable. The armored optical cable generates an alternating magnetic field under the action of the current excitation signal. The magnetic signal detection module is located inside the sheath and is used to detect the alternating magnetic field generated by the armored optical cable to obtain the position information of the armored optical cable. The sheath-exposed optical cable detection system applies an excitation current to the armored optical cable outside the sheath. Under the action of the excitation current, the armored optical cable outside the sheath generates its own alternating magnetic field. The magnetic signal detection module detects the alternating magnetic field generated by the armored optical cable to determine the position information of the armored optical cable. This invention increases the intensity of the electromagnetic signal by having the armored optical cable itself generate an alternating magnetic field, thereby improving the detection accuracy.

[0030] Figure 1 This is a schematic diagram of the structure of the armored optical cable when it deflects according to an embodiment of the present invention, as shown below. Figure 1 As shown, during casing lowering, the relative position of the optical cable and the casing is easily deflected, causing the cable's distribution path downhole to bend. This results in the casing's metal mass high-side curve changing with the cable's distribution path, placing new demands on the azimuth detection capabilities of downhole tools. Furthermore, the optical cable's dimensions are typically much smaller than the circumference of the downhole casing, and accurate detection and positioning of the cable during motion measurement also places higher demands on the circumferential resolution of the detection system.

[0031] Figure 2 This is a schematic diagram of the structure of the armored optical cable outside the sheath provided in an embodiment of the present invention. Figure 3 This is a side view of the armored optical cable outside the sheath provided in an embodiment of the present invention. Figure 4 This is a cross-sectional view of the armored optical cable outside the sheath provided in an embodiment of the present invention, as shown below. Figure 2-4 As shown, this embodiment provides an armored optical cable with an outer sheath, including: an optical fiber unit, a first steel wire rope 02, a second steel wire rope 03, and a connecting conductor 10; The first steel wire rope 02 and the second steel wire rope 03 are disposed on both sides of the optical fiber unit; The first steel wire rope 02 at the end of the armored optical cable located underground is connected to the second steel wire rope at the end of the armored optical cable located underground via the connecting conductor 10; When the first wire rope 02 and the second wire rope 03 at the end of the armored optical cable located on the ground are connected to the ground electrode at the wellhead, the armored optical cable and the ground electrode 06 form a conductive circuit. The ground electrode 06 is used to apply alternating current excitation to the armored optical cable so that the armored optical cable generates an alternating magnetic field.

[0032] In this embodiment, the optical fiber unit is a data transmission medium that can transmit various parameters monitored downhole to the surface in real time.

[0033] The first steel wire rope 02 and the second steel wire rope 03 are used to enhance the tensile strength of the optical cable. The first steel wire rope 02 and the second steel wire rope 03 have the same structure, consisting of 7 galvanized steel wires with an outer diameter of 2.14 mm.

[0034] In this embodiment, the optical fiber unit includes: an optical fiber 01 and a sheath steel tube 04, with the sheath steel tube 04 sleeved on the outside of the optical fiber 01.

[0035] In this embodiment, there are multiple sheathing steel tubes 04, which are successively fitted around the optical fiber 01, with the diameter of the multiple sheathing steel tubes 04 increasing progressively. That is, the sheathing steel tubes 04 adopt a multi-layered circular ring structure.

[0036] In this embodiment, the sheathing steel pipe 04 is used to protect the optical cable from external forces such as tension. The material of the sheathing steel pipe 04 is magnetic, which helps in the detection of magnetic signals in the armored optical cable.

[0037] In this embodiment, the armored optical cable further includes: an outer sheath 05; The outer sheath 05 is used to encapsulate the optical fiber unit, the first steel wire rope 02, the second steel wire rope 03, and the connecting wire 10.

[0038] In this embodiment, the outer sheath 05 is made of polypropylene, which can play a role in corrosion prevention and other functions.

[0039] When laying armored fiber optic cables on casing in the well, a surface derrick is typically used to lower the armored fiber optic cable and casing together into the well. The armored fiber optic cable is then secured to the casing using cable clamps. Each cable clamp is locked in place by the protruding edges on both sides of the casing coupling, and the armored fiber optic cable is placed in the cable slot within the clamp. An additional cable clamp is added with each casing section laid, thus fixing the armored fiber optic cable to the outer wall of the casing.

[0040] In existing technologies, traditional armored optical cables utilize transient electromagnetic detection methods, employing a transmitting coil containing a magnetic core as the primary magnetic field source. Because traditional armored optical cables possess magnetism and conductivity, eddy currents are generated, leading to a secondary alternating magnetic field. By using a sensor coil or sensor array placed inside the casing to receive the magnetic field, the location of the outer armored optical cable can be analyzed. However, in reality, the casing provides some shielding for electromagnetic signals, causing significant attenuation of the electromagnetic signal generated by the transmitting probe. Furthermore, the small and slender structure of the outer armored optical cable results in very weak changes in the magnetic field, leading to a weak received signal and hindering high-precision detection of the outer armored optical cable.

[0041] To achieve precise positioning of the sheathed armored optical cable, this invention improves the intensity of the measured magnetic signal by connecting the first steel wire rope 02 and the second steel wire rope 03 through the connecting wire 10, forming a conductive loop with the ground electrode 06. The ground electrode 06 provides a large current excitation to the conductive loop, causing the sheathed optical cable to generate a strong alternating magnetic field. Due to the presence of the sheathed optical cable, the original magnetic field information changes significantly, thereby enabling the detection and positioning of the sheathed armored optical fiber 01. The sheathed armored cable provided by this invention solves the problem in the prior art that high-precision detection of sheathed armored optical cables cannot be achieved.

[0042] Figure 5 This is a schematic diagram of the structure of the sheathed optical cable inspection system provided in an embodiment of the present invention. Figure 6 This is a schematic diagram showing the connection between the armored optical cable and the ground electrode 06 provided in an embodiment of the present invention. Figure 7 This is a schematic diagram of the structure of the magnetic field sensor ring array 07 provided in an embodiment of the present invention. Figure 5-7 As shown, the sheathed optical cable detection system provided in this embodiment is used to detect the armored optical cable outside the sheath as described above. The system includes: an electromagnetic excitation module and a magnetic signal detection module. The electromagnetic excitation module includes: a ground electrode 06, which is connected to the ground end of the armored optical cable and is used to send a current excitation signal to the armored optical cable; The armored optical cable generates an alternating magnetic field under the action of the current excitation signal; The magnetic signal detection module is located inside the sleeve. The magnetic signal detection module is used to detect the alternating magnetic field generated by the armored optical cable to obtain the position information of the armored optical cable.

[0043] In this embodiment, the electromagnetic excitation module is located on the ground, eliminating the need for a transmitter module within the casing and reducing the complexity of the downhole circuitry. The electromagnetic excitation module provides excitation to the optical cable, enhancing the electromagnetic signal and improving detection accuracy and interpretation reliability. Furthermore, the electromagnetic excitation module only requires a single ground electrode (06), eliminating the need for a downhole transmitter module, resulting in a simple structure and low design cost.

[0044] In this embodiment, the magnetic signal detection module includes: a magnetic field sensor ring array 07; The magnetic field sensor ring array 07 is distributed inside the sleeve. The magnetic field sensor ring array 07 includes multiple magnetic field sensors arranged in a ring array. All multiple magnetic field sensors detect the alternating magnetic field generated by the armored optical cable to obtain alternating magnetic field information.

[0045] In this embodiment, the magnetic signal detection module further includes: circuit unit 08; The circuit unit 08 is communicatively connected to multiple magnetic field sensors to receive alternating magnetic field information collected by the multiple magnetic field sensors and to determine the position information of the armored optical cable based on the multiple alternating magnetic field information.

[0046] In this embodiment, the magnetic signal detection module further includes: a remote transmission unit 09; The remote transmission unit 09 is used to transmit the location information of the armored optical cable determined by the circuit unit 08 to the ground data receiving device.

[0047] In this embodiment, the system further includes: armored logging cables and a wellhead surface logging vehicle; One end of the armored logging cable is connected to a magnetic signal detection module, and the other end of the armored logging cable is connected to the wellhead surface logging vehicle; The wellhead surface logging vehicle lowers the magnetic signal detection module into the casing via the armored logging cable.

[0048] In this embodiment, the data receiving device is mounted on the wellhead surface logging vehicle.

[0049] Figure 8 This is a flowchart of the external optical cable testing method provided in the embodiments of the present invention, such as... Figure 8 As shown, this embodiment provides a method for detecting external optical cables under a sheath, including: S1. A current excitation signal is sent to the armored optical cable through an electromagnetic excitation module; wherein, the armored optical cable is an armored optical cable with an outer sheath as described above; S2. The armored optical cable generates an alternating magnetic field under the action of an electric current excitation signal; S3. The alternating magnetic field generated by the armored optical cable is detected by the magnetic signal detection module to obtain the position information of the armored optical cable.

[0050] In step S1, sending a current excitation signal to the armored optical cable via the electromagnetic excitation module includes: The ground end of the armored optical cable is connected through the ground electrode 06 so that the ground electrode 06 and the armored optical cable form a conductive loop, and the ground electrode 06 provides a current excitation signal for the conductive loop.

[0051] Furthermore, the current value in the current excitation signal is greater than the first preset value.

[0052] In step S3, the method of using the magnetic signal detection module to detect the alternating magnetic field generated by the armored optical cable and obtain the position information of the armored optical cable includes: Multiple magnetic field sensors arranged in a ring array are used to detect the alternating magnetic field information of the armored optical cable in each direction; The location information of the armored optical cable is determined based on alternating magnetic field information from multiple directions.

[0053] The present invention also provides a computer device, including: a memory, a processor, and a computer program, the computer program being stored in the memory and configured to be executed by the processor to implement the above-described method for detecting external optical cables under sheaths.

[0054] This invention also provides a machine-readable storage medium storing computer program instructions, which, when executed by a processor, implement the above-described method for detecting external optical cables in sheaths.

[0055] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0056] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0057] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. As long as such combination does not violate the spirit of the embodiments of the present invention, it should also be considered as the content disclosed by the embodiments of the present invention.

Claims

1. An armored optical cable for use outside a casing in oil wells, characterized in that, The armored optical cable includes: an optical fiber unit, a first steel wire rope, a second steel wire rope, and a connecting conductor; The first steel wire rope and the second steel wire rope are disposed on both sides of the optical fiber unit; The first steel wire rope at the underground end of the armored optical cable is connected to the second steel wire rope at the underground end of the armored optical cable via the connecting conductor. When the first and second steel wire ropes at the ground end of the armored optical cable are connected to the ground electrode at the wellhead, the armored optical cable and the ground electrode form a conductive circuit. The ground electrode is used to apply alternating current excitation to the armored optical cable to generate an alternating magnetic field.

2. The armored optical cable outside the sheath according to claim 1, characterized in that, The optical fiber unit includes an optical fiber and a sheath steel tube, wherein the sheath steel tube is sleeved on the outside of the optical fiber.

3. The armored optical cable outside the sheath according to claim 2, characterized in that, There are multiple sheathing steel pipes, which are successively fitted over the optical fiber, and the diameter of the multiple sheathing steel pipes increases progressively.

4. The armored optical cable outside the sheath according to claim 2, characterized in that, The armored optical cable also includes: an outer sheath; The outer sheath is used to encapsulate the optical fiber unit, the first steel wire rope, the second steel wire rope, and the connecting wire.

5. A sheathed optical cable detection system for detecting armored optical cables outside the sheath as described in any one of claims 1-4, characterized in that, The system includes: an electromagnetic excitation module and a magnetic signal detection module; The electromagnetic excitation module includes: a ground electrode, which is connected to the ground end of the armored optical cable and is used to send a current excitation signal to the armored optical cable; The armored optical cable generates an alternating magnetic field under the action of the current excitation signal; The magnetic signal detection module is located inside the sleeve. The magnetic signal detection module is used to detect the alternating magnetic field generated by the armored optical cable to obtain the position information of the armored optical cable.

6. The sheathed external optical cable inspection system according to claim 5, characterized in that, The magnetic signal detection module includes: a ring array of magnetic field sensors; The magnetic field sensor ring array is distributed inside the sheath. The magnetic field sensor ring array includes multiple magnetic field sensors arranged in a ring array. All multiple magnetic field sensors detect the alternating magnetic field generated by the armored optical cable to obtain alternating magnetic field information.

7. The sheathed external optical cable inspection system according to claim 6, characterized in that, The magnetic signal detection module further includes: a circuit unit; The circuit unit is communicatively connected to multiple magnetic field sensors to receive alternating magnetic field information collected by the multiple magnetic field sensors and to determine the position information of the armored optical cable based on the multiple alternating magnetic field information.

8. The sheathed external optical cable inspection system according to claim 7, characterized in that, The magnetic signal detection module further includes: a remote transmission unit; The remote transmission unit is used to send the location information of the armored optical cable determined by the circuit unit to the ground-based data receiving device.

9. The sheathed external optical cable inspection system according to claim 8, characterized in that, The system also includes: armored logging cables and a wellhead surface logging vehicle; One end of the armored logging cable is connected to a magnetic signal detection module, and the other end of the armored logging cable is connected to the wellhead surface logging vehicle; The wellhead surface logging vehicle lowers the magnetic signal detection module into the casing via the armored logging cable.

10. The sheathed external optical cable inspection system according to claim 9, characterized in that, The data receiving device is located on the wellhead ground logging vehicle.

11. A method for detecting optical cables outside a sheath, characterized in that, include: The electromagnetic excitation module sends a current excitation signal to the armored optical cable, wherein the armored optical cable is the sheathed armored optical cable as described in any one of claims 1-4. Armored optical cables generate alternating magnetic fields under the action of current excitation signals; The location information of the armored optical cable is obtained by detecting the alternating magnetic field generated by the armored optical cable using a magnetic signal detection module.

12. A computer device, characterized in that, include: Memory, which stores computer programs; A processor for executing the computer program to implement the method for detecting external optical cables as described in claim 11.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program is executed by a processor to implement the external optical cable detection method of claim 11.

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