Multi-parameter underground optical fiber probe

Abstract

Aspects of the invention relate to fiber optic probes, in particular but not limited to multi-parameter fiber optic probes, and particularly but not limited to methods and devices for preparing and deploying multi-parameter fiber optic probes. The invention particularly relates to an oil well logging technology, in particular to a disposable multi-parameter measuring instrument for an oil and gas well based on an optical fiber sensing technology. Comprising a probe capable of releasing an optical fiber, a sealed penetrating assembly and an acquisition device. The probe adopts a plurality of independent optical fiber bobbins, and one optical fiber is wound on each independent optical fiber bobbin, so that synchronous sensing of multiple parameters such as temperature, acoustics and pressure is realized; a pre-twisting-free process is adopted for optical fiber winding, high-temperature-resistant adhesive is coated between layers, a stepped unwinding structure is formed, and stable unwinding is ensured. And the sealing penetrating assembly realizes high-pressure sealing transmission through a stepped threaded hole channel and a sealing agent doped with metal powder. The acquisition device is connected with the probe through an optical fiber and acquires and demodulates the sensing signal in real time. The device has the advantages of being rapid in deployment, low in cost, high in safety, degradable and the like, and is suitable for multi-parameter real-time monitoring of vertical wells, inclined wells and horizontal wells.

Description

Technical Field

[0001] This invention relates to various aspects of fiber optic probes, specifically, but not limited to, multi-parameter fiber optic probes, and particularly, but not limited to, methods and apparatus for preparing and deploying multi-parameter fiber optic probes. In particular, this invention relates to oil well logging technology, and more specifically, to a disposable multi-parameter measuring instrument for oil and gas wells based on fiber optic sensing technology. Background Technology

[0002] Well logging, acting as the "underground eyes" of oil and gas exploration and development, is crucial throughout the entire resource development lifecycle, serving as a core element to ensure exploration accuracy, production efficiency, and operational safety. During the exploration phase, complex underground geological conditions prevent direct observation. Well logging uses downhole instruments to collect physical parameters of rock formations (such as resistivity, sonic transit time, and density), accurately identifying reservoir lithology, determining the distribution of oil, gas, and water layers, and solving the critical question of "what's underground?" This prevents well failures due to geological interpretation biases, significantly reducing exploration risks and costs. In the development phase, well logging can monitor reservoir dynamics in production wells in real time (such as changes in reservoir pressure and water cut trends), providing data support for developing reasonable production plans (such as determining perforation locations and adjusting injection and production parameters), avoiding resource waste or well condition deterioration caused by blind extraction.

[0003] Traditional well logging relies on cable or fiber optic transmission and electromechanical sensing to detect downhole parameters. Its core method involves running logging instruments equipped with sensors into the wellbore via cable or fiber optic cable to collect real-time data on the physicochemical properties of the rock formation (such as resistivity, acoustic velocity, formation density, and natural gamma intensity). This data is then transmitted to a surface system for processing and analysis, ultimately enabling reservoir identification, oil, gas, and water layer differentiation, and well condition evaluation. However, as oil and gas exploration extends to deep wells, ultra-deep wells, unconventional reservoirs (such as shale gas and coalbed methane), and areas with complex geological conditions (such as salt-gypsum layers and fracture zones), the limitations of traditional well logging technology are becoming increasingly apparent, presenting multiple problems: Firstly, it suffers from low operational efficiency and poor adaptability—traditional well logging relies on cable / fiber optic transmission, resulting in slow instrument setup and setup speeds (typically only a few kilometers per hour), with single-well logging cycles potentially reaching several days. Especially in deep or horizontal wells, cables / fiber optic cables are prone to tangling, obstruction, or even stuck instruments due to irregular wellbore conditions, not only delaying operations but also potentially causing instrument damage or cable breakage accidents. Secondly, the high cost and significant safety risks are significant. The purchase and maintenance costs of cable logging equipment are exorbitant, often reaching hundreds of thousands of yuan per well. Furthermore, operations require large equipment such as logging trucks and wellhead equipment, increasing the complexity of on-site operations. Thirdly, as the only connection between the surface and the well, a break in the cable / fiber optic cable can not only lead to the loss of the instrument but may also clog the wellbore. Subsequent retrieval operations are costly and difficult, and may even result in the wellbore becoming unusable.

[0004] In recent years, disposable fiber optic logging technology has gradually emerged. It simplifies the operation process by lowering fiber optic sensors into the well and leaving them downhole to degrade naturally after the operation is completed. However, existing disposable fiber optic probes have limited functionality, typically measuring only a single parameter such as temperature or acoustics, which cannot meet the needs of complex engineering projects.

[0005] Fiber winding technology for reel-type fiber deployment typically employs pre-twisting to counteract torsional stress generated by the relative movement of the pay-off spool and the rotating mandrel. Existing conventional methods include: horizontal spiral winding with lateral movement, slotted orthogonal cyclic arrangement for improved fill factor, and figure-eight or reverse winding patterns for controlling interlayer transitions. To ensure the stability of the winding structure during handling and pay-off, adhesives or protective layers are applied between layers. Meanwhile, a typical design for downhole multi-parameter fiber optic probes integrates distributed temperature sensing (DTS) on multimode fiber and distributed acoustic / vibration sensing (DAS) on single-mode fiber, achieving point pressure / temperature measurements via fiber Bragg gratings (FBG) or Fabry-Perot elements. These probes are typically integrated into permanent downhole cables or cable / slide wire tools, with the surface end connected to the DTS, DAS, and FBG demodulation unit via a pressure-resistant wellhead feedthrough for signal acquisition.

[0006] The aforementioned technical solutions face numerous challenges: pre-twisting winding increases the number of process steps and is sensitive to equipment debugging accuracy; residual torsion during the winding process can be released in the form of loops, kinks, or torque-driven crossovers, leading to increased attenuation, introducing polarization / phase noise detrimental to acoustic sensing, and increasing the risk of layer edge jamming; improper control of interlayer reverse and tool retraction can lead to "telescoping"; improper selection and coating of adhesives can result in coil winding slack or, in severe cases, excessive bonding between turns, causing microbending and static friction. For downhole multi-parameter probes, co-encapsulated optical fibers are prone to mechanical coupling and crosstalk, and the winding speed of different channels may be inconsistent; in addition, achieving low-loss withstand voltage penetration of multiple bare optical fibers under high pressure differential and high temperature environments is also quite difficult. Existing deployment methods mostly rely on derricks or cable equipment, which have a large ground footprint, high cost, and high safety risks; if non-degradable tools fail to be recovered, they can become "fallen fish" (downhole debris) or block the wellbore. Summary of the Invention

[0007] The objective of this invention is achieved through the following technical solution.

[0008] According to one aspect of this application, a method is provided for winding optical fibers onto an optical fiber spool without pre-twisting, the optical fiber spool including a core, the method comprising: winding optical fibers from an optical fiber spool to the core to form a first layer of optical fibers; and winding optical fibers from the optical fiber spool to the core to form a second layer of optical fibers.

[0009] According to another aspect of this application, the method involves applying an adhesive between the first layer of optical fiber and the second layer of optical fiber.

[0010] According to another aspect of this application, the first layer of optical fiber is wound from a first position to a second position on the mandrel; and the second layer of optical fiber is unwound from the second position to the first position one or more times, such that the grooves of the second layer of optical fiber are aligned with those of the first layer of optical fiber.

[0011] According to another aspect of this application, the method further includes aligning the core of the optical fiber spool with the optical fiber reel, wherein the fiber feed direction from the optical fiber reel and the fiber take-up direction at the core are respectively along the radial tangent direction of their respective components.

[0012] According to another aspect of this application, the mandrel rotates in a first rotation direction and at a first speed to take in the wire; the fiber optic reel rotates in a first rotation direction and at a second speed associated with the first speed to release the wire; and the first speed and the second speed are set based on the radii of the mandrel and the fiber optic reel.

[0013] According to another aspect of this application, the first or second layer of optical fiber has the thickness of a single optical fiber.

[0014] According to another aspect of this application, it also includes winding an additional layer of optical fiber, such that the winding steps of the first and second layers of optical fiber are repeated.

[0015] According to another aspect of this application, the multilayer optical fiber forms an unwound structure at a second position on the mandrel.

[0016] According to another aspect of this application, the unwinding structure is in the shape of an oblique trapezoid.

[0017] According to another aspect of this application, the adhesive is a high-temperature resistant adhesive.

[0018] According to another aspect of this application, the adhesive is applied in the following manner: during the winding process, the optical fiber is passed through the adhesive box to achieve automatic adhesive application; or the adhesive is applied to one or more layers of optical fiber before or after winding.

[0019] According to another aspect of this application, the first position is a limiting plate for restricting the axial positioning of the optical fiber.

[0020] According to another aspect of this application, the second position is a chamfered structure to prevent the first layer of optical fiber from being pulled out of the mandrel when the probe is released and to not obstruct the cable laying.

[0021] According to another aspect of this application, the outer diameter of the optical fiber is 0.6 mm or less.

[0022] According to one aspect of this application, a probe for downhole fiber optic deployment is provided, the probe comprising at least three fiber optic spools, each fiber optic spool being configured to wind a single fiber optic cable, and each fiber optic cable of the at least three fiber optic spools being independent of each other.

[0023] According to another aspect of this application, the at least three fiber optic spools can be deployed synchronously to achieve synchronous multi-parameter sensing.

[0024] According to another aspect of this application, the probe also includes a fiber optic pressure gauge, which comprises a pressure grating and a temperature compensation grating.

[0025] According to another aspect of this application, the probe also includes a protective housing for protecting the at least three fiber optic spools downhole.

[0026] According to another aspect of this application, the protective housing employs a compact array structure to accommodate the at least three fiber optic spools.

[0027] According to another aspect of this application, the lower end of the protective shell is provided with a guide head for stabilizing the probe deployment process or guiding the probe during descent.

[0028] According to another aspect of this application, the probe also includes an upper connector for detachable connection with a probe deployment device, downhole tool, or other deployment equipment.

[0029] According to another aspect of this application, the optical fiber includes single-mode optical fiber, multimode optical fiber, or engineered optical fiber.

[0030] According to another aspect of this application, the optical fiber is made of a dissolvable material, allowing the optical fiber to be used once downhole (without the need for recycling).

[0031] According to another aspect of this application, the multiple parameters include temperature data, pressure data, acoustic data, vibration data, strain data, strain rate data, seismic data, microseismic data, other applicable distributed measurement data, or combinations of the above data.

[0032] According to another aspect of this application, the fiber optic pressure gauge employs a single-ended fiber optic output structure and includes a fiber Bragg grating sensor or a fiber Fabry-Perot sensor.

[0033] According to another aspect of this application, the probe is fabricated and deployed using the aforementioned fiber optic winding method that does not require pre-twisting, i.e., by winding the fiber from the fiber optic spool onto the core shaft to form a first layer, and then winding a second layer.

[0034] According to one aspect of this application, a sealed passage assembly for high-voltage to low-voltage transition of optical fiber is provided. The passage axis of the assembly is provided with a channel whose diameter gradually decreases from the high-voltage end to the low-voltage end. The channel contains one or more optical fibers and is provided with a sealant for sealing the one or more optical fibers within the channel.

[0035] According to another aspect of this application, the inner wall of the channel has a stepped structure, and the diameter of the channel gradually decreases from the high-pressure end to the low-pressure end.

[0036] According to another aspect of this application, the channel is filled with a high-temperature resistant sealant containing metal powder for sealing the optical fiber passing through the penetrating shaft.

[0037] According to another aspect of this application, the inner wall of the channel is provided with one or more threads, grooves or indentations.

[0038] According to another aspect of this application, the sealed through-axis assembly further includes: an armored sheath for protecting the optical fiber extending from the penetration shaft at the low-voltage end, or a protective sleeve for centering and positioning the optical fiber at the high-voltage end, or both.

[0039] According to one aspect of this application, a multi-parameter sensing device for downhole applications is provided, the device comprising: a probe for deploying an optical fiber downhole to achieve multi-parameter sensing; a sealed pass-through assembly for enabling a high-voltage to low-voltage transition of the optical fiber of the probe; and a data acquisition device; the data acquisition device being connected to the optical fiber of the probe via the sealed pass-through assembly for acquiring one or more sensing signals from the optical fiber.

[0040] According to another aspect of this application, the multi-parameter sensing device further includes a probe deployment device.

[0041] According to another aspect of this application, the probe deployment device includes: a blowout preventer for installation at the wellhead; a blowout preventer head installed on top of the blowout preventer (the blowout preventer head has a pressurization port that can be connected to an external pressurization device to pressurize the inside of the blowout preventer); a release piston disposed inside the blowout preventer for fixing and releasing the probe under pressure; a sealing penetration assembly disposed on the blowout preventer head for sealing at least one optical fiber passing through the probe; and a pressure relief valve disposed on the blowout preventer for releasing residual pressure inside the blowout preventer after deployment.

[0042] According to another aspect of this application, the through-axis of the sealing through-assembly is provided with a channel, the diameter of which decreases from the high-pressure end to the low-pressure end. The channel contains one or more optical fibers and a sealant for sealing the optical fibers. The channel may have a stepped inner wall with one or more threads / grooves / dents. The sealant is a high-temperature resistant sealant mixed with metal powder. The low-pressure end is provided with an armored sleeve and / or the high-pressure end is provided with a protective sleeve.

[0043] According to another aspect of this application, the acquisition device includes a distributed temperature sensor (DTS) connected to a multimode optical fiber of the probe for acquiring a wellbore temperature profile via the multimode optical fiber.

[0044] According to another aspect of this application, the acquisition device includes a distributed optical fiber acoustic vibration analyzer (DAS) connected to a single-mode optical fiber of a probe for monitoring vibration signals at one or more points within the wellbore via the single-mode optical fiber.

[0045] According to another aspect of this application, the acquisition device includes a distributed optical fiber acoustic analyzer (DAS) connected to a single-mode optical fiber of the probe for monitoring vibration signals or locating the probe position via the single-mode optical fiber.

[0046] According to another aspect of this application, the acquisition device includes a fiber Bragg grating (FBG) demodulator connected to a fiber optic pressure gauge of the probe for demodulating the signal from the fiber optic pressure gauge to obtain pressure data.

[0047] According to another aspect of this application, the probe adopts the structure of the above-mentioned "probe for releasing optical fiber in downhole well", that is, it includes at least three optical fiber spools, each spool having an independent optical fiber wound around it, and can be deployed for multi-parameter sensing.

[0048] According to one aspect of this application, an optical fiber cable material is provided that can be dissolved downhole in an oil and gas well.

[0049] The optical fibers or fiber optic coils mentioned above may include single-mode fiber, multimode fiber, bare fiber, standard fiber, or combinations thereof. The fiber optic spools can be arranged in an array to ensure synchronous unwinding and release of the fiber optic probe during its lowering process. Compared to traditional single-axis or dual-axis fiber optic probe designs, this instrument can simultaneously sense multiple parameters including temperature, acoustics, and pressure, offering enhanced functionality and higher testing efficiency.

[0050] Furthermore, the fiber optic coils can all be made of communication-grade or engineering-grade optical fiber; the length of each fiber optic coil is preferably not less than the depth of the well to be measured.

[0051] The winding method described in this application has significant advantages: it can produce twist-free, compact coils with controllable wire release resistance, reducing micro-bending and polarization noise, while achieving smooth, unobstructed wire release from stepped unwinding and trapezoidal coil structures. This design improves the signal fidelity of distributed temperature and acoustic sensing and ensures the stability of the grating used for pressure measurement. The probe structure with three independent fiber optic spools enables truly synchronous, interference-free acquisition of multiple parameters (temperature, vibration / acoustics, pressure), with stable and matched wire release tension. Real-time position monitoring is achieved through characteristic wire release vibration, making it suitable for vertical, deviated, and horizontal wells. The sealed through-hole assembly combines stepped threaded channels with a high-temperature resistant sealant containing metal powder to achieve low-loss transmission under high pressure differentials, resisting compression and creep while protecting the optical fiber from compression and eccentricity, ensuring optical integrity under thermal cycling. The deployment device enables derrick-free, safe, and rapid operation through pressure balancing and pressurized release, reducing ground footprint, personnel requirements, and operation time. The fully passive, power-free fiber optic probe enhances safety in hazardous environments, while the soluble structure eliminates salvage risks and environmental legacy issues, reducing total lifecycle costs and carbon footprint.

[0052] This invention meets the complex engineering requirements of simultaneous, real-time, and high-precision monitoring of temperature, acoustics, and pressure. Furthermore, the probe's structural design, multi-fiber synchronous winding and reliable release technology, and high-pressure dynamic sealing deployment technology solve the wellhead bottleneck problem in existing technologies.

[0053] This disposable downhole measurement system enables simultaneous measurement of multiple parameters, rapid deployment, low cost, intrinsic safety, and environmental friendliness.

[0054] Those skilled in the art should understand that any of the above-described devices, processes, systems, and methods are not limited to wellbore deployment and can be applied to other scenarios. Attached Figure Description

[0055] The embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a schematic diagram of an exemplary embodiment of optical fiber being wound from a spool to a reel; Figure 2 is a schematic diagram of an exemplary embodiment of the probe; Figure 3 is a schematic diagram of an exemplary embodiment of the sealing through-hole assembly; Figure 4 is a schematic diagram of an exemplary embodiment of the multi-parameter sensing device; Figure 5 is a schematic diagram of an exemplary embodiment of the probe deployment device; Figure 6A is a schematic diagram of an exemplary embodiment of an optical fiber spool; Figure 6B is a schematic diagram of an exemplary embodiment of the pressure gauge; Figure 7 is a flowchart of the optical fiber winding method; Figure 8 shows the vibration curves measured by the distributed acoustic sensor / vibration analyzer during the probe lowering process; Figure 9A shows the temperature change curves recorded in real time by the distributed temperature sensor from the moment the probe is deployed to the bottom of the well and after water injection; Figure 9B shows the temperature curves measured by the distributed temperature sensor 24 hours after the well was shut in; Figure 10A shows the temperature curves measured by the distributed temperature sensor 8 hours after water injection; Figure 10B shows the vibration curves measured by the distributed acoustic sensor / vibration analyzer during the water injection process.

[0056] Explanation of reference numerals in the attached figures: 1. Probe, 2. Probe deployment device, 3. Acquisition device, 4. Upper connector, 5. Protective housing, 6. Fiber optic spool, 7. Fiber optic pressure gauge, 8. Flow guide head, 9. Winding frame (core shaft), 10. Fiber optic coil, 11. Sealing and passing assembly, 11. Penetration shaft 11-1, Blowout nozzle, 12. Release piston, 13. Blowout pipe, 14. Pressure relief valve, 15. Distributed temperature sensor (DTS), 16. Distributed fiber acoustic vibration analyzer (DAS), 17. Fiber Bragg grating (FBG) demodulator, 18. Adapter cable, 19. Fiber optic cable, 20. High-temperature resistant sealant, 21. Fiber optic coil, 22.

[0057] All accompanying drawings are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0058] First, it should be clearly understood that those skilled in the art will readily recognize that this application has broad applicability and application scenarios. It should be understood that any embodiment may include only one or more aspects of the above-described application, and may further include one or more features of the above-described application. Furthermore, any embodiment referred to as "preferred" is considered one of the best ways to implement the embodiments of this application.

[0059] To fully and completely disclose the present invention, other embodiments will be discussed below for further illustration. Furthermore, numerous embodiments (such as adaptations, variations, modifications, and equivalents) will be implicitly disclosed by the embodiments described herein and fall within the scope of protection of this application. Therefore, although one or more embodiments of this application are described in detail below, it should be understood that the scope of protection of this application is defined by the appended claims, and not by the detailed description below. Limitations implied in the detailed description below should not be interpreted as limitations on the scope of protection of the claims. In addition, special attention should be paid to the fact that each term used herein should be understood by those skilled in the art based on its meaning in the context herein. If the meaning of a term in the context herein (as understood by those skilled in the art) differs from any particular dictionary definition of that term, the meaning understood by those skilled in the art shall prevail. Finally, it should be noted that "a" or "an" generally means "at least one," unless explicitly required by the context; "or," when used to connect multiple items, means "at least one of the items," but does not exclude combinations of multiple items; and "and," when used to connect multiple items, means "all of the items."

[0060] The following detailed description will be taken in conjunction with the accompanying drawings. Where possible, the same reference numerals are used in the drawings and the following description to refer to the same or similar elements. Although multiple embodiments of this application may be described, modifications, adaptations, and other implementations are possible. For example, elements shown in the drawings may be replaced, added, or modified, and the methods described herein may be modified by replacing, reordering, or adding steps. Therefore, the following detailed description does not limit this application, and the scope of protection of this application is defined by the appended claims.

[0061] This application includes headings, but it should be understood that these headings are for reference only and should not be construed as limiting the scope of the applications under those headings. Other technical advantages will be readily apparent to those skilled in the art upon review of the accompanying drawings and description below. It should be understood from the outset that although exemplary embodiments are shown below with reference to the accompanying drawings and description, the principles of this application can be implemented by any known or future technology. This application should not be limited in any way to the exemplary implementations and technologies shown and described below.

[0062] Unless otherwise stated, the accompanying drawings should be read in conjunction with the instruction manual and are considered an integral part of the entire written instruction manual. The terms “horizontal,” “vertical,” “left,” “right,” “up,” “down,” and their adjective / adverb derivatives (such as “horizontally,” “to the right,” “upward,” “radially,” etc.) used herein refer only to the orientation of the structure shown when the accompanying drawings are facing the reader. Similarly, “inward,” “outward,” and “radially” generally refer to the orientation of a surface relative to its axis of extension or axis of rotation (as the case may be).

[0063] It should be noted that any system, method or process of this application includes at least one processing unit, and the at least one processing unit performs the process of this invention. Detailed Implementation

[0064] The embodiments of this application will now be described with reference to the accompanying drawings. It should be noted that the following description is only intended to help those skilled in the art understand this application and is not intended to limit the application scenarios of this application (other application scenarios can be easily conceived by those skilled in the art). Specifically, although this application mainly targets wellbore monitoring, logging, and intervention in oil and gas wells, those skilled in the art should understand that the apparatus, processes, methods, and systems described herein can also be applied to geothermal wells, carbon capture and storage (CCS) injection / monitoring wells, brine treatment and water injection wells, underground gas storage facilities, and other high-pressure pipelines or containers that require fiber optic sensing and pressure-resistant feedthrough. For example, this disposable multi-parameter probe can be used for geothermal well thermal front and water absorption profile monitoring, or, through the same winding, probe, and sealing components, for injection profile monitoring and annular integrity verification during CCS processes.

[0065] Figure 1 is a schematic diagram of an exemplary embodiment of the winding mandrel. Specifically, Figure 1 shows an optical fiber winding mandrel that does not require pre-twisting.

[0066] The fiber optic spool 6 includes a core spool 9; the fiber optic cable 20 is released from the fiber optic reel 22 and wound onto the core spool 9 in a direction tangential to its respective component. The fiber optic cable is wound as follows: the first layer is wound from a first position to a second position on the core spool 9, and the second layer is unwound one or more turns from the second position before being wound back to the first position; this design aligns the second layer of fiber with the groove of the first layer, forming a compact fiber optic coil 10. The multi-layered fiber optic cable forms a stepped unwinding structure at the second position on the core spool.

[0067] Preferably, an adhesive is applied between the first layer of optical fiber and the second layer of optical fiber.

[0068] Optionally, in order to achieve torsion and tension control without pre-twisting, the rotation direction and speed of the spindle 9 need to be matched with the rotation direction and speed of the fiber optic reel 22.

[0069] According to one embodiment, the fiber optic spool 6 includes a core 9 and a fiber optic coil 10. The left side of the fiber optic spool 6 has a chamfer of a certain height to prevent the fiber optic cable 20 from slipping off, while not obstructing the release of the fiber optic coil 10 when the probe 1 is released. A baffle is installed on the right side to limit the axial position of the fiber optic coil 10. The fiber optic coil 10 is formed by stacking multiple layers of closely arranged optical fibers 20, and bare optical fibers or optical fibers with special coatings can be selected according to application conditions. For ease of winding, the outer diameter of the optical fiber is preferably no greater than 0.6 mm.

[0070] It should be clarified that the application content of any optical fiber 20 in this document refers to an optical fiber including a core, cladding, and coating; the coating can improve the shear strength and tensile limit of the optical fiber. Optionally, the optical fiber may be without a coating, or may use a special coating; in addition, a protective outer layer may be applied to the outside of the optical fiber, or the optical fiber may be made part of an optical cable. For example, optical fiber 20 may be bare optical fiber or standard optical fiber.

[0071] As shown in Figure 1, the fiber optic reel 22 and the mandrel 9 are respectively mounted on the winding machine, and their axes are parallel. During the winding process, the fiber optic reel 22 and the mandrel 9 rotate in the same direction at corresponding speeds: the fiber optic reel 22 releases the fiber, and the mandrel 9 takes the fiber in; and the release and take-up directions are both along the radial tangent direction of their respective components. Therefore, there is no need to release torsional stress through pre-torsion, nor is any additional torque introduced. When the fiber optic cable 20 on the mandrel 9 moves to the right turn by turn, the release shaft also moves laterally to the right at a corresponding speed.

[0072] The first layer of fiber is uniformly wound on the surface of the mandrel. To reduce the difficulty of interlayer transition during winding, when winding the second layer, it is necessary to start by unwinding a few turns from the left (for example, first wind a few turns to the right, then wind to the left), so that this layer of fiber is uniformly nested in the groove of the first layer, until it reaches the right baffle. The third layer starts from the rightmost baffle and winds to the left, stopping at the position where the second layer started to unwind. Subsequent layers are wound in a similar manner, so that the leftmost fiber forms a stepped unwinding structure layer by layer. In this example, the cross-section of the completed fiber coil is a right trapezoid, which ensures that the fiber is released synchronously and smoothly during the probe lowering process.

[0073] To prevent the wound fiber coil from loosening and to provide sufficient resistance to maintain the tension of the released fiber, a high-temperature resistant adhesive needs to be applied between the fiber layers during the winding process. The application method can be either automatic adhesive application by passing the fiber through the adhesive box during winding, or manual application of adhesive after each layer is wound.

[0074] In another exemplary embodiment, the surface of the mandrel / winding frame 9 needs to be treated to promote interlayer bonding of the fiber coil 10 while preventing the fiber from bonding to the mandrel 9. The surface of the mandrel 9 is coated with a low surface energy release coating to suppress fiber-mandrel interface bonding; a finely textured surface is processed to stabilize the alignment of the fiber 20 during interlayer reverse winding, ensuring that each turn of fiber is within its groove. The surface finish needs to be carefully selected to avoid lateral micro-slippage when tension is applied, while ensuring smooth wire release when the fiber coil 10 is downhole.

[0075] In another embodiment, adjustable damping is provided on the fiber optic reel 22, and an active take-up device is provided on the mandrel 9 to achieve active control of tension and torque, ensuring that the tangential surface velocity at the fiber contact circumference is matched during winding. This kinematic matching can suppress the axial rotation of the fiber 20 and ensure that the winding angle remains constant during winding. Simultaneously, synchronous lateral translation is applied: when the mandrel 9 moves axially to place each turn of fiber, the fiber optic reel 22 also translates laterally at a corresponding speed, keeping the winding path straight and approximately in the same plane, avoiding local twisting or crossing due to offset.

[0076] The first and second axial reference points on the mandrel 9 are defined by a chamfer at one end and a baffle at the other end, respectively. The chamfer height needs to be carefully designed to prevent the fiber 20 from creeping over the edge while ensuring that the outermost fiber can be laid freely; the chamfer angle needs to be selected to distribute contact pressure and reduce coating wear on the edge fibers. The baffle provides an axial positioning stop for the fiber coil 10, suppressing telescoping during winding and subsequent handling.

[0077] The interlayer bonding adhesive must be compatible with the fiber 20 coating and the expected thermochemical environment downhole. The high-temperature resistant formulation must be able to wet the grooves between adjacent turns while avoiding excessive overflow onto the outer periphery or chamfer / baffle edges. The adhesive viscosity must be adjusted according to the winding speed to ensure the formation of a thin, uniform film between layers, which, after curing, is flexible—providing controllable winding resistance while maintaining the roundness of the fiber 20 and avoiding microbending losses.

[0078] Depending on the operational requirements, fiber 20 can be bare fiber or coated with a special coating suitable for high temperatures, chemical corrosion resistance, or enhanced abrasion resistance, but the outer diameter must be within the allowable range to achieve single fiber thickness nesting on the mandrel 9. The selected diameter must facilitate slot alignment of subsequent layers and ensure that the adhesive film is thin enough not to fill the inter-turn grooves, thus maintaining a compact packing density.

[0079] For applications involving large temperature fluctuations, the coefficients of thermal expansion of the adhesive and optical fiber 20 must be considered—interlayer bonding must provide damping and cohesion while not restricting the deformation of the coil during heating / cooling. A combination of chamfers, baffles, a controlled unwinding structure at the second point, and a flexible adhesive film ensures that the optical fiber coil 10 maintains its geometry during storage, handling, and the entire unwinding process, while the coordinated movement of the mandrel 9 and the optical fiber reel 22 ensures that the net torsion introduced during winding is close to zero.

[0080] In another embodiment, after winding is completed, a slight axial preload is applied to the fiber coil 10 by briefly increasing the take-up torque of the mandrel 9, making the coil structure compact (without deforming the fiber 20), followed by a brief pressure hold to allow the adhesive to reach a viscous state. This operation achieves uniform interlayer contact and predictable initial release tension, ensuring that the released fiber remains taut during probe lowering and reducing the risk of loops or kinks when the coil passes through chamfered edges.

[0081] Figure 2 is a schematic diagram of the probe. Specifically, Figure 2 shows a probe 1 comprising three or more fiber optic spools 6 and a fiber optic pressure gauge 7; optionally, the probe may also include any or all of the following components: a protective housing 5, an upper connector 4, and / or a flow guide head 8.

[0082] According to one embodiment, probe 1 is a disposable downhole component with a slender overall structure to fit the internal space of the tubing. It includes an upper connector 4, a protective shell 5, a flow guide head 8, at least three independent fiber optic spools 6, and a fiber optic pressure gauge 7. The protective shell 5 houses the three independent fiber optic spools 6 in a compact array structure; as shown in Figure 1, each fiber optic spool 6 includes a winding frame / core 9 and a fiber optic coil 10, carrying fiber optics for different purposes (e.g., single-mode fiber for acoustic / vibration sensing, single-mode fiber for fiber optic pressure gauge signal transmission, and multimode fiber for temperature sensing). This multi-spool independent design is the physical basis for achieving synchronous multi-parameter measurement, ensuring that multiple fibers can be unwound and released synchronously, smoothly, and without interference during probe deployment.

[0083] In another exemplary embodiment, the protective shell 5 is a thin-walled, high-strength sleeve with internal positioning ribs that fix three fiber optic spools 6 in an array (the spool axes are parallel to the probe 1 axis), ensuring uniform coaxiality of the spools and uniform radial clearance between the spools and the shell wall. Each fiber optic spool 6 is mounted on a keyway-equipped carrier, which fixes the axial position of the spool and prevents the spindle 9 from rotating relative to the carrier (during transport). A flexible insulating element is provided between the carrier and the protective shell 5 to attenuate impacts and vibrations while preventing spool misalignment. The protective shell 5 has pressure balancing holes and bypass holes to allow well fluid to flow into the interior, preventing pressure differentials on both sides of the fiber optic coil 10 and reducing fluid resistance during probe lowering.

[0084] The guide head 8 is a streamlined, through-type head with rounded inlet and outlet edges and a longitudinal bypass channel to reduce turbulence and stabilize the lowering posture of the probe 1. The guide head 8 integrates a fiber optic cable delivery channel with a polished, low-friction surface (radius meets requirements) to prevent wear on the fiber optic cable 20 when released from each fiber optic spool 6 and to ensure the fiber optic bending radius is not less than the minimum value. An independent cable divider is located at the outlet to prevent contact between fibers from different spools, avoiding crosstalk and jamming. The mass of the guide head 8 needs careful design to provide sufficient head load to ensure vertical alignment of the probe, while matching the overall buoyancy with the expected lowering speed.

[0085] The upper connector 4 serves as the mechanical connection interface for probe 1 (used for connecting and releasing the probe). It contains an internal strain relief structure to secure the upper end of the optical fiber 20. The anti-bending structure within the upper connector 4 ensures that the optical fiber bending radius is not less than the minimum value, and the gasketed channel secures the direction of each optical fiber 20 from the optical fiber spool 6 to the inside of the connector, preventing local bending or twisting of the optical fiber during the cable laying process from being transmitted to the internal termination point. Furthermore, the upper connector 4 also acts as the structural head, bearing axial loads during deployment and protecting internal components from impact.

[0086] The fiber optic pressure gauge 7 is mounted on a flexible support inside the protective housing 5. This support transmits hydrostatic pressure while filtering axial and bending loads transmitted by the probe 1 structure. The protective housing 5 has a pressure exposure window / interface aligned with the fiber optic pressure gauge 7, allowing direct contact between the well fluid and the gauge. The window is equipped with a filter and a smooth flow channel to prevent particles from entering and damaging the sensing components. The pressure gauge's fiber optic pigtail is routed with controlled slack and secured with a soft clamp to prevent micro-bending. The pigtail's service loop length must be fixed to prevent interference with the fiber optic spool 6's routing path.

[0087] Each fiber spool 6 has a localized fiber feeding guide structure at the chamfered edge of the mandrel 9, which guides the outermost fiber of the fiber coil 10 into the channel of the guide head 8, preventing fiber corner wear or scratches. The interlayer adhesive of the fiber coil 10 provides slight and predictable damping; optionally, a low-damping element is provided at the bearing of the mandrel 9, both working together to generate stable feeding tension and ensure matching feeding tension of the three fiber spools 6. The chamfered / baffle structure of the mandrel 9 works in conjunction with the stepped retraction structure of the fiber coil 10 to prevent edge jamming and ensure synchronous and smooth feeding of all spools.

[0088] The fiber optic cabling inside the protective housing 5 employs dedicated channels: the fibers from each spool 6 to the guide head 8, and from the spool 6 to the upper connector 4, are all routed through independent channels; the channel surfaces are polished and lined with a low-friction material to reduce fiber attenuation and coating wear. The channel geometry and spacing ensure physical separation of the fibers corresponding to temperature sensing, acoustic / vibration sensing, and pressure sensing, preventing mechanical disturbances in one channel from being transmitted to another, and ensuring sensing fidelity during deployment and monitoring.

[0089] Structural components such as the protective shell 5, mandrel 9, and guide head 8 can be manufactured using soluble or biodegradable materials. These materials must be able to withstand the loads during handling and deployment, and degrade as expected in the well fluid after operation. The connection and sealing structures must be designed to maintain dimensional stability during operation, not generate obstructive debris during degradation, and ensure the harmless decomposition of the fiber optic coil 10 and internal components.

[0090] The mass and hydrodynamic characteristics of probe 1 need to be balanced in the design so that the center of mass is located in front of the hydrodynamic center defined by the protective shell 5 and the guide head 8, ensuring a self-stabilized attitude during the lowering process. The three fiber optic spools 6 are symmetrically arranged around the axis of probe 1, which can reduce yaw and roll excitation caused by well fluid flow; the bypass hole on the protective shell 5 can reduce vortex-induced vibration, further protecting the integrity of the fiber optic cable 20 and the stability of the cable laying.

[0091] Although three fiber optic spools 6 are shown in the figure, the probe 1 can be flexibly configured with one, two, three or more fiber optic spools 6 depending on the number of sensing parameters.

[0092] In another embodiment, the assembly process of probe 1 is as follows: The fiber optic spool 6, pre-wound according to the requirements of the mandrel 9 and fiber optic coil 10, is installed in place; the fiber optic pressure gauge 7 is installed, with its fiber optic pigtail routed as required and strain released; the protective shell 5 is closed to enclose the spool array, and then the connector 4 and the guide head 8 are fixed in place. The final test verifies that: the fiber optic cables of each fiber optic spool 6 can be freely and independently routed through the channel of the guide head 8; all fibers 20 are correctly placed in the curved guide structure; and the structural integrity of the protective shell 5 meets the requirements.

[0093] Figure 3 is a schematic diagram of the sealing through assembly. Specifically, Figure 3 shows an exemplary embodiment of the sealing through assembly 11.

[0094] The sealed pass-through assembly 11 is used to achieve the transition of optical fiber from high voltage to low voltage without generating significant signal loss or affecting operation. This assembly includes a pass-through shaft 11-1 with a channel within it for accommodating a sealant; the diameter of the channel gradually decreases from the high-voltage end to the low-voltage end, and one or more threads are provided within the channel. Optionally, the assembly also includes an armored sheath for protecting the optical fiber extending from the pass-through shaft at the low-voltage end; preferably, the assembly also includes a protective sleeve for centering and positioning the optical fiber at the high-voltage end.

[0095] According to one embodiment, the sealed optical fiber penetration assembly 11 includes an armored sheath, an optical fiber 20, a penetration shaft 11-1, a high-temperature resistant sealant 21, a pigtail protective sleeve, and a high-temperature resistant tubing. The selected high-temperature resistant sealant 21 must have excellent adhesion to the optical fiber 20 (with the coating removed from the bonding section); when the bonding length is sufficient, it can provide ample bonding area to ensure reliable bonding and prevent crushing failure under high pressure.

[0096] The internal design of the penetration shaft 11-1 is a stepped channel, with the diameter gradually decreasing from the high-pressure end to the low-pressure end, forming a pressure gradient. The inner wall of the channel is threaded to maximize the contact area between the sealant and the wall surface, and the steps and threads withstand the stress generated by high pressure. Further, optionally, a suitable amount of metal powder (e.g., particle size not less than 100 mesh) is premixed into the high-temperature resistant sealant to improve the sealant's compressive strength and prevent excessive deformation of the sealant under high pressure, which could lead to damage to the optical fiber.

[0097] This sealed through-hole structure enables laser pulse transmission and reception across multiple optical fibers under a maximum voltage difference of 100 MPa with virtually no loss. Due to the larger outlet diameter at the high-voltage end of the through-hole axis, a pigtail protective sleeve is required to center and position the fibers, preventing eccentricity. Simultaneously, a high-temperature resistant loose tube provides bending protection for the high-voltage pigtail. The low-voltage pigtail is protected by an armored sheath.

[0098] The penetrating shaft 11-1 is preferably an integral pressure-bearing body. Its internal stepped channels are formed by multiple cylindrical segments connected by short conical surfaces, with the smallest aperture located at the low-pressure end (to limit the extrusion path of the high-temperature sealant 21). One or more cylindrical segments have threads machined on their inner walls, increasing the effective bonding area between the high-temperature sealant 21 and the wall surface, and providing mechanical engagement points for the sealant under pressure differential. The gradual decrease in aperture from high to low pressure creates a pressure gradient within the high-temperature sealant 21, dispersing circumferential and axial loads and reducing localized stress concentration at the optical fiber 20.

[0099] The bonding preparation process for fiber optic cable 20 is as follows: Remove the outer coating to the specified bonding length to expose the glass surface; clean and activate the glass surface to improve adhesion; pass the fiber optic cable from the high-voltage side through the pigtail protective sleeve (ensuring concentricity at the entry point), through the high-temperature resistant sealant 21 area within the penetration shaft 11-1, and into the high-temperature resistant sleeve (providing bend protection); on the low-voltage side, fiber optic cable 20 transitions into the armored sheath (providing mechanical protection and strain relief). Throughout the cabling process, ensure that the fiber optic cable bending radius is not less than the minimum value to avoid attenuation caused by micro-bending.

[0100] The high-temperature resistant sealant 21 needs to be injected into the channel under controlled conditions: preferably, the sealant should be degassed first, and if necessary, vacuum-assisted injection should be used to eliminate voids at the threads and steps; the premixed metal powder in the sealant can improve compressive stiffness, reduce creep under load, and prevent the overall deformation of the sealant under high pressure differential from causing pressure on the optical fiber 20. The sealant needs to be cured into a flexible, high-temperature resistant state, which must maintain adhesion to the optical fiber 20 and be able to withstand thermal cycling to avoid cracks at the optical fiber-sealant interface.

[0101] The bonding length needs to be designed in conjunction with the thread and stepped structure of the penetration shaft 11-1 to ensure that the overall shear capacity of the interface between the optical fiber 20 and the high-temperature sealant 21 is greater than the axial force pushing the optical fiber 20 under the maximum pressure difference (with a safety margin). The pressure gradient generated by the reduced aperture of the stepped design can reduce the peak shear stress at the interface of any section; the thread acts as a shear engagement point, transferring the load of the high-temperature sealant 21 to the wall of the penetration shaft 11-1. From an optical performance perspective, the pressure sealing section must not introduce losses—that is, the optical fiber 20 must not be subjected to excessive strain (otherwise it will affect the measurement results of distributed acoustic sensing (DAS) and other measurements).

[0102] To ensure optical performance, the curing shrinkage rate and modulus of the high-temperature sealant 21 must be controlled to limit its radial pressure on the optical fiber 20, thereby minimizing microbending loss and polarization disturbance. The protective sleeve on the high-voltage side ensures the concentricity of the optical fiber at the large entrance aperture, avoiding eccentric loads; the high-temperature loose tube isolates the bending moment of the bonding section. The armored sheath on the low-voltage side fixes the optical fiber 20, preventing tensile loads from being transferred to the bonding area.

[0103] For embodiments accommodating multiple optical fibers 20, the penetration shaft 11-1 can be designed as: multiple parallel stepped threaded channels (each channel filled with sealant 21), or a larger common cavity (with spacers inside to prevent contact between optical fibers during curing and operation). Each optical fiber 20 is equipped with an independent protective sleeve at the high-voltage end and an independent armored sleeve at the low-voltage end to achieve independent strain release and avoid crosstalk caused by mechanical coupling.

[0104] The sealing through-axis assembly 11 must pass the following verifications: hydrostatic pressure testing (pressure not lower than the design working pressure difference), thermal cycling testing (temperature range covering the expected downhole value), and low-pressure side leakage testing. During the verification process, optical continuity must be monitored to ensure that the insertion loss of the assembly does not change significantly under pressure and temperature, thereby confirming that the combination of the through-axis 11-1 structure, the high-temperature resistant sealant 21 formulation, and the fiber optic 20 wiring can achieve reliable low-loss signal transmission.

[0105] Figure 4 is a schematic diagram of a multi-parameter sensing device. Specifically, Figure 4 shows a multi-parameter device including a probe 1 (for deploying optical fibers downhole to achieve multi-parameter sensing). The device also includes a sealed pass-through assembly 11 for enabling a high-voltage to low-voltage transition of the probe's optical fibers, and a data acquisition device 3 (connected to one or more optical fibers 20 of the probe 1 via the sealed pass-through assembly 11); therefore, the data acquisition device 3 can acquire one or more sensing signals from the probe 1.

[0106] Optionally, the multi-parameter device is a disposable multi-parameter measuring instrument for oil and gas wells based on fiber optic sensing technology. According to this embodiment, the device includes a disposable fiber optic probe 1, a probe deployment device 2, and a data acquisition device 3; these three parts are connected via fiber optic paths to form a complete measurement system. Preferably, this embodiment is a stand-alone, plug-and-play well logging monitoring technology, allowing operators and / or the operating system to quickly grasp the well condition through high-definition temperature or acoustic profile images.

[0107] A disposable fiber optic probe 1 is connected to the acquisition device 3 via an optical fiber and is used to lower into the oil well and release the optical fiber in real time to achieve multi-parameter sensing. The probe deployment device 2 is preferably based on a lightweight design (e.g., using a lightweight high-strength alloy) and is reusable; this device is installed at the wellhead to accommodate and release the disposable fiber optic probe 1. The acquisition device 3 includes any or all of the following: a distributed temperature sensor (DTS), a distributed fiber acoustic vibration analyzer (DAS) 17, and a fiber Bragg grating (FBG) demodulator 18; this device is connected to the optical fiber of the disposable fiber optic probe 1 via an adapter cable 19, and is used to receive and demodulate the optical signal from the disposable fiber optic probe, while simultaneously acquiring data such as temperature, vibration, and pressure.

[0108] The deployment of this multi-parameter device requires no derrick and can be achieved quickly via probe deployment device 2; the entire system can ideally be set up by two personnel within 3 hours. After the operation is completed, on-site personnel cut the optical fiber at the wellhead; the optical fiber and its soluble outer shell, which are lowered into the well, will degrade and disappear within days or weeks.

[0109] Preferably, any or all of the structural components of the probe (such as the protective shell 5, the mandrel 9, etc.) are made of soluble or biodegradable composite materials; within days or weeks after the operation is completed, these components can self-dissolve, break down and degrade in the well fluid environment, eliminating the need for complicated retrieval operations, avoiding well blockage, and being more environmentally friendly.

[0110] In this embodiment, the real-time positioning of the disposable fiber optic probe 1 employs distributed fiber optic vibration sensing technology: after the probe deployment device 2 successfully releases the disposable fiber optic probe 1, the probe is lowered into the oil pipe at a certain speed, and the three fiber optic coils are simultaneously unwound; among them, the fiber released from the spool connected to the distributed fiber acoustic vibration analyzer (DAS) 17 (exhibiting specific characteristic vibrations) exhibits different vibration characteristics than the fiber still tightly wound on the spool (relatively stationary). By demodulating the different vibration characteristics at this critical point in real time, the characteristic position can be located, thereby obtaining the position information of the disposable fiber optic probe 1 in real time.

[0111] The acquisition device 3 is installed in the equipment room or monitoring room at the well site. It is responsible for transmitting detection light signals and receiving / demodulating the light signals carrying physical field information returned from downhole.

[0112] Figure 5 is a schematic diagram of the probe deployment device. Specifically, the probe deployment device 2 is a reusable device that is fixedly installed at the wellhead, used to safely and controllably complete the probe deployment and fiber optic sealing crossing under extremely high wellhead pressure.

[0113] The device includes: a blowout preventer 14 serving as the main pressure-bearing housing, a blowout preventer head 12 fixed to the top of the blowout preventer 14, a release piston 13 for fixing and releasing the probe under pressure, a sealing through assembly 11 for high-pressure dynamic sealing of multiple bare optical fibers, and a pressure relief valve 15 for safe pressure relief.

[0114] In this embodiment, the sealing through-hole assembly 11 uses a high-temperature resistant sealant 21 mixed with metal powder to seal the optical fiber 20 passing through the penetration shaft 11-1 (as shown in Figure 4). The selected high-temperature resistant sealant 21 has good adhesion to the optical fiber 20; when the bonding length is sufficient, a sufficient bonding area can be formed between the two, ensuring reliable bonding and preventing extrusion failure under high pressure. The penetration shaft 11-1 is internally designed as a stepped channel, with the aperture gradually decreasing from the high-pressure end to the low-pressure end, forming a pressure gradient; the inner wall of the channel is machined into a thread shape to maximize the contact area between the sealant and the wall surface, and to withstand the stress generated by high pressure through the steps and threads. In addition, premixing an appropriate amount of metal powder into the high-temperature resistant sealant can improve its compressive strength and prevent excessive deformation of the sealant under high pressure, which could lead to damage to the optical fiber. This through-sealing method can realize laser pulse transmission and reception of multiple optical fibers under a maximum pressure difference of 100MPa with almost no loss.

[0115] The blowout preventer 12 has a pre-installed pressurization interface. Before deployment, the blowout preventer 14 can be pressurized using an external pump to balance the internal pressure of the blowout preventer with that of the tubing, thereby eliminating pressure differential and facilitating the safe opening of the Christmas tree valves. The release piston 13 is designed with threads, seals, and a safety limit structure, and is equipped with an extension rod operating tool; even under maximum system pressure, operators can manually loosen the piston to smoothly complete the probe deployment. The entire process is safe, controllable, and easy to operate.

[0116] Figure 6A is a schematic diagram of an optical fiber spool. Specifically, Figure 6A shows an alternative structure for the optical fiber spool 6 in Figure 1. It should be noted that the probe 1 and device described herein are not limited to the winding method described herein.

[0117] Figure 6B is a schematic diagram of the pressure gauge. Specifically, Figure 6B shows a high-precision fiber optic pressure gauge 7 integrated inside probe 1. In this embodiment, the fiber optic pressure gauge 7 is based on the fiber Bragg grating (FBG) sensing principle and employs a side-pressure structure to convert ambient pressure into a wavelength shift of the pressure measurement grating. By monitoring the wavelength shift, changes in ambient pressure can be inverted. As shown in Figure 6B, the sensor incorporates a temperature-compensated grating with one end free—providing temperature compensation for the pressure measurement grating while simultaneously measuring the ambient temperature. The maximum operating pressure of this pressure gauge is not less than the maximum operating pressure inside the oil pipe.

[0118] Figure 7 is a flowchart of the optical fiber winding method. Specifically, Figure 7 shows method 100, which includes steps 102 and 104, and step 104 includes steps 106, 108 and 110.

[0119] Step 102 (Preparation): Install the winding frame / mandrel 9 and the fiber optic reel 22 on the winding machine, ensuring their axes are parallel. Release the fiber optic cable 20 from the circumferential tangential direction of the fiber optic reel 22 and take it back from the circumferential tangential direction of the mandrel 9. Set the mandrel 9 and fiber optic reel 22 to rotate in the same direction with matched angular velocities (determined based on their effective radii). Set synchronous lateral translation—when the mandrel 9 moves axially, the fiber optic reel 22 translates laterally at a corresponding speed to ensure uniform cable laying. Set the tension range of the fiber optic cable 20 using the adjustable damping of the fiber optic reel 22 and the controllable torque of the mandrel 9 to eliminate residual torsion (no pre-torsion required). Define the first and second axial reference points on the mandrel 9 to limit the winding range of the fiber optic coil 10. Verify that the diameter of the selected fiber optic cable 20 supports inter-slot nesting and compact arrangement on the mandrel 9. Prepare the adhesive delivery path (do not start yet), ensuring the cable laying path, the axial stop on the mandrel 9, and the fiber optic coil 10 are properly aligned. The wire feeding gap allows for interference-free winding in steps 106 and 108 and adhesive coating in step 110.

[0120] Step 104 (winding and adhesive application): includes Step 106 (first layer winding), Step 108 (second layer winding) and Step 110 (adhesive application).

[0121] Step 106 (First Layer Winding): Starting from the first axial reference point near the chamfered end of the mandrel 9, the first layer of optical fiber 20 is wound uniformly towards the second axial reference point near the baffle end. During the winding process, the optical fiber 20 is released from the tangential direction of the optical fiber reel 22 and taken back from the tangential direction of the mandrel 9, while maintaining the same rotation and lateral translation set in step 102. The axial translation speed needs to be set such that adjacent optical fiber turns are in contact with a single optical fiber thickness (without overlap), forming a regular spiral structure (the grooves between the turns provide a workstation for subsequent layer nesting), while maintaining a constant wiring angle and uniform winding of the optical fiber coil 10. The tension is controlled by the damping of the optical fiber reel 22 and the torque of the mandrel 9 to prevent slight buckling of the optical fiber and maintain the roundness of the optical fiber 20. The translation endpoint needs to be limited to: not exceeding the chamfered edge and not contacting the baffle end, thereby defining clear first and second point boundaries for this layer and ensuring that the optical fiber coil 10 can be laid out without obstruction.

[0122] Step 108 (Second Layer Winding): Starting from the second axial reference point, retreat one or more turns, and wind the second layer of optical fiber 20 towards the first axial reference point; each turn of optical fiber is nested within the spiral groove formed in the first layer, forming a winding layer of single-fiber thickness, while maintaining a constant laying angle of the optical fiber coil 10. During the winding process, the optical fiber coil 22 and the mandrel 9 maintain the same rotation and synchronous lateral translation set in step 102; the tension setting must prevent lateral micro-slippage and micro-bending, while maintaining the roundness of the optical fiber 20. The translation range must be limited to: not contacting the chamfered end and not exceeding the baffle end, thereby forming a controlled retraction at the second axial reference point, constructing a stepped retraction shoulder for subsequent layers, ensuring that the optical fiber coil 10 can be laid out without obstruction.

[0123] Step 110 (Adhesive Coating): Apply adhesive between adjacent fiber layers on the mandrel 9 to provide interlayer cohesion and controllable feeding resistance (without hindering subsequent feeding); the coating method can be selected as follows: allow the fiber 20 to pass through the adhesive box (forming a uniform film upstream of the contact point of the mandrel 9), or pause rotation and brush a thin and continuous adhesive film onto the completed layers. The viscosity and delivery rate of the adhesive need to be adjusted so that it only wets the groove between the lower layer turns, without overflowing onto the outer periphery, chamfered edges, or baffle ends; and ensure that the fiber 20 does not stick to the mandrel 9 (this can be achieved by applying a release coating to the non-target surface of the mandrel 9). During the coating process, the co-rotation and synchronous lateral translation of the mandrel 9 and the fiber optic coil 22 need to be maintained at a low speed to control the film thickness and prevent lateral micro-slippage; the tension needs to be maintained within the set range to maintain the roundness of the fiber 20 and avoid displacement of the nested turns. After coating, a short pressure holding period is required to allow the adhesive to reach a viscous state (to prevent subsequent turns from floating or shifting); during this period, the uniformity of coating in the width direction should be visually inspected periodically to ensure that there are no gaps and that the adhesive does not contaminate the critical free surfaces of the layup.

[0124] Preferably, step 104 is repeated until the fiber optic spool 6 is wound: that is, the sequence of steps 106→110→108→110 is repeated on the mandrel 9, and the fiber optic coil 10 is wound layer by layer until the fiber optic coil 10 reaches the target capacity, outer diameter or mass, while maintaining the set tension and translation limit.

[0125] Optionally, in step 102, co-rotation control can be introduced: the mandrel 9 and the bobbin 22 are set to rotate in the same direction and their angular velocities are matched to ensure that the tangential surface velocities at the fiber contact circumference of the two are consistent during the winding process; this design can suppress residual torsion (without pre-torsion) and stabilize the winding angle in steps 106 and 108; the tension is controlled by the damping of the bobbin 22 and the driving torque of the winding frame 9.

[0126] Optionally, in steps 106 and 108, it is necessary to ensure the thickness of the single optical fiber winding: set the axial translation pitch of the mandrel 9 so that adjacent optical fiber turns are in side-by-side contact (without overlap or gap) to form a uniform groove to promote the nesting between grooves and the compact arrangement of the optical fiber coil 10.

[0127] Optionally, a stepped back shoulder is formed at the second axial reference point of the mandrel 9: in steps 106 / 108, each time a layer is wound in the reverse direction, one or more turns are backed from the boundary of the second point, thereby forming an accumulated stepped profile to ensure that the fiber coil 10 can be reliably laid out at this edge.

[0128] Optionally, by maintaining the consistent retraction amount of each reverse layer and the winding thickness of a single optical fiber in steps 106 and 108, the cross-section of the optical fiber coil 10 is formed into an oblique trapezoid; this geometry can facilitate synchronous release and reduce the risk of jamming at the edge of the second point during deployment.

[0129] Optionally, in steps 102, 106, 108, and 110, the fiber optic reel 22 needs to be moved laterally synchronously: when the spindle 9 moves axially, the fiber optic reel 22 moves laterally at a corresponding speed to ensure a uniform cable laying path and prevent the fiber optic cable 20 from crossing or shifting at the contact point.

[0130] Optionally, in step 110, a high-temperature resistant adhesive must be selected to ensure that the interlayer bonding of the fiber coil 10 maintains cohesion and controllable wire release resistance in the downhole environment; the adhesive must be able to wet the inter-turn grooves of the fiber 20 and remain flexible at high temperatures (avoiding embrittlement or excessive overflow).

[0131] Optionally, the adhesive application method in step 110 can be: either pass the optical fiber 20 through the adhesive box (forming a uniform film upstream of the core 9), or brush a thin and continuous film onto the completed layer; both methods require reducing the line speed to control the film thickness, avoid lateral micro-slippage, and prevent the adhesive from contaminating the critical surface of the wire laying.

[0132] Optionally, the axial reference points defined in step 102 are: the first point is set at the baffle end of the mandrel 9 (to limit the axial position of the fiber), and the second point is set at the chamfer end of the mandrel 9 (to prevent the fiber from slipping and not to obstruct the laying), thereby providing clear boundaries for the layer initiation, reversal and stepped retraction structure.

[0133] This method uses dynamic matching for pay-off and take-up to ensure that the optical fiber 20 experiences almost no net rotation around its own axis between the fiber optic reel 22 and the mandrel 9, thus eliminating the need for pre-twisting. The optical fiber 20 is paid off and taken up tangentially, while the fiber optic reel 22 and mandrel 9 rotate in the same direction, with their angular velocities set to match the tangential surface velocities at the fiber contact circumference. Synchronous lateral translation makes the pay-off path approximately planar and straight, avoiding axial rotation caused by offset. Within a set tension range, the optical fiber 20 is wound in a bent form on the fiber optic coil 10 (geometric winding), without accumulating axial torsion. The reverse direction of the cable arrangement is limited by the chamfered end and baffle end of the mandrel 9, preventing edge-driven rotational events.

[0134] The advantages of this twist-free winding are: it suppresses stored torsion released during the pay-off process (avoiding loops, tangles, or "telephone line" kinks), reduces microbending loss, fusion stress, and coating shear at high temperatures; it stabilizes the phase and polarization state of the fiber 20 (beneficial for vibration sensing), maintains low and uniform attenuation of temperature sensing, and avoids residual torsional deviations in the integrated grating of the fiber pressure gauge 7. The thin interlayer adhesive film provides uniform damping (preventing the fiber 20 from bonding to the core 9), generating consistent pay-off resistance, ensuring the released fiber remains taut, and making the pay-off tension profile of each spool 6 predictable, thereby promoting synchronous and interference-free release of the fiber through the guide head 8 and reducing stress concentration at the penetration axis 11-1.

[0135] The following describes other process examples not illustrated: System connection and preparation: Seal and install the probe deployment device 2, which houses the fiber optic probe 1, on the tree; connect the fiber optic probe 1 to the adapter cable 19 of the acquisition device 3; check the connectivity and signal quality of the entire optical path.

[0136] Pressure balancing: Pressurize the inside of the deployment device through the pressurization port on the nozzle 12; monitor the pressure with a pressure gauge until the pressure inside the deployment device is balanced with the pressure inside the oil pipe.

[0137] Probe Deployment and Real-Time Positioning: Open the wellhead valve and slowly loosen and release piston 13; fiber optic probe 1 is lowered along the tubing at a certain speed under gravity, and the three fiber optic spools 6 inside the probe are simultaneously and smoothly released under fluid resistance. During the probe lowering process, the acquisition device 3 is activated simultaneously: the DAS / vibration analyzer identifies the critical point of vibration characteristics between "fiber optic cable released from spool (with characteristic vibration)" and "fiber optic cable still tightly wound (relatively stationary)," and combines this with optical time domain reflectance (OTDR) positioning technology to achieve real-time and accurate positioning of the probe lowering depth and speed.

[0138] Synchronous multi-parameter monitoring: Once the probe reaches the target position or naturally settles to the bottom of the well, the system enters the comprehensive monitoring phase: DTS continuously plots high-resolution wellbore temperature profiles; DAS sensitively captures and locates acoustic / vibration signals generated during fracturing, injection, and fluid production processes; the FBG demodulator records the pressure change history at the bottom of the well (or probe position) at a high sampling rate. These three types of data are synchronized in time and correlated in space, thereby achieving comprehensive real-time diagnosis and monitoring of well conditions.

[0139] Operation completion and degradation: After the monitoring task is completed, the optical fiber is cut at the wellhead and the acquisition device 3 and probe deployment device 2 are retrieved; the disposable optical fiber probe 1 left in the well will gradually soften, dissolve and decompose over time under the action of the well fluid, and the optical fiber itself will also break; eventually all materials will disperse into the well fluid and will not affect subsequent production operations.

[0140] Figures 8 to 10B are examples of sensing data acquired by the probes and / or devices described herein.

[0141] The ground acquisition device 3 in this embodiment includes: a distributed temperature sensor (DTS) 16 (connected to a multimode fiber for acquiring wellbore temperature profiles via the multimode fiber), a distributed fiber acoustic vibration analyzer (DAS) 17 (connected to a single-mode fiber for monitoring vibration signals and locating probe positions in real time via the single-mode fiber), and a fiber Bragg grating (FBG) demodulator 18 (connected to a fiber optic pressure gauge 7 for demodulating the fiber optic pressure gauge signal to obtain pressure data); the above devices are integrated and connected via an adapter cable 19.

[0142] In this example (non-limiting), probe 1 and probe deployment device 2 are installed on the wellhead tree, and acquisition device 3 is located in the oilfield equipment room. Before deployment, the pressure inside the tubing is balanced by an external pressurizing device. Then, the wellhead valve is opened, and the release piston 13 on probe deployment device 2 is loosened. Release piston 13 separates from upper connector 4, and disposable fiber optic probe 1 is lowered into the tubing at a certain speed, with the fiber optic coil 10 inside being laid out synchronously. DAS / vibration analyzer 7 acquires the vibration signal at the fiber optic laying point in real time, realizing the real-time positioning of disposable fiber optic probe 1 (as shown in Figure 8, Figure 8 is the vibration curve 800 measured by the distributed acoustic sensor / vibration analyzer during the probe lowering process, and amplitude scale 802 represents the relative amplitude).

[0143] The Distributed Temperature Sensor (DTS) 16 records the temperature change curves in real time from the initial deployment of the disposable fiber optic probe 1 to the bottom of the well and after water injection (as shown in Figure 9A, which is the temperature change curve 900-A recorded in real time by the distributed temperature sensor from the initial deployment of the probe to the bottom of the well and after water injection; the temperature scale 902 represents the relative temperature). It can be seen from the figure that when the multimode fiber is wound on the mandrel 9, the internal stress of the fiber causes the temperature measurement value to fluctuate periodically; when the fiber is completely released, the stress is released, and the temperature measurement value tends to normalize. Figure 9B (temperature curve 900-B measured by the distributed temperature sensor 24 hours after well shut-in) and Figure 10A (temperature curve 1000-A measured by the distributed temperature sensor 8 hours after water injection) show the temperature curves after different well shut-in times: after 24 hours of well shut-in, the temperature curve gradually increases with depth; after 8 hours of water injection, the temperature near the wellhead increases significantly. Figure 10B (Vibration curves measured by a distributed acoustic sensor / vibration analyzer during water injection 1000-B) shows the vibration curves measured by the DAS / vibration analyzer when the water injection rate is 32 cubic meters / day. The figure shows a strong vibration signal at a depth of approximately 2300m, indicating that this location is a water-absorbing layer. Therefore, by monitoring the vibration signal, the precise location information of the water-absorbing layer in the oil well can be identified.

[0144] The probe 1 in this embodiment has significant advantages: it contains three independent fiber optic spools, which, when used with corresponding ground acquisition equipment, can simultaneously monitor multiple parameters such as temperature, vibration, and pressure; this disposable fiber optic probe can enter vertical, deviated, or horizontal wells, and optimize shale gas well completion and fracturing operations by monitoring strain events in adjacent wells during fracturing; it can also evaluate the effectiveness of perforation and well completion designs and verify integrity issues; the positioning accuracy can reach 1m resolution, and it can record and monitor acoustic events.

[0145] Compared with traditional logging methods such as cables or fiber optic cables, this oil and gas well uses a one-time multi-parameter measuring instrument, which is faster, significantly reduces operating costs, reduces personnel requirements, and reduces carbon emissions from well site operations.

[0146] This disposable probe enables simultaneous measurement of three key parameters: temperature, vibration, and pressure. It achieves multiple benefits, is powerful, and significantly increases the amount of information and testing efficiency in a single operation.

[0147] The system does not rely on large derricks and logging vehicles. It is lightweight and modular, and only two people are needed to complete all the setup and deployment work in 2-3 hours, which fundamentally reduces operating costs, time costs and personnel requirements.

[0148] This downhole probe is a fully passive, pure fiber optic device that requires no power supply, fundamentally eliminating the risk of ignition by electrical sparks. It is particularly suitable for flammable and explosive oil and gas well environments, and its safety is unparalleled.

[0149] The fiber trapezoidal winding process and arrayed spool design ensure absolute reliability for the synchronous release of multiple optical fibers; the innovative stepped thread high-pressure sealing through-pass assembly ensures stable signal transmission under extreme high-pressure environments; and optical fibers themselves have the natural advantages of high temperature resistance and electromagnetic interference resistance.

[0150] This probe is biodegradable, solving the problems of permanent wellbore blockage and environmental damage caused by lost instruments in traditional cable logging, which aligns with the concept of green oilfield development.

[0151] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A sealed crossing assembly for fiber optic transition from high voltage to low voltage, characterized in that, The through-axis of the sealed through-axis assembly includes a channel with a diameter that gradually decreases from the high-pressure end to the low-pressure end; the channel contains one or more optical fibers; and the channel is configured to contain a sealant for sealing the one or more optical fibers within the channel.

2. The sealing through-flow assembly according to claim 1, characterized in that: The inner wall of the channel is stepped, so that the circumference of the channel gradually decreases from the high-pressure end to the low-pressure end.

3. The sealing through-pass assembly according to claim 2, characterized in that: The channel contains a high-temperature resistant sealant mixed with metal powder, which is used to seal the optical fiber inserted through the through-axis.

4. The sealing through-pass assembly according to claim 3, characterized in that: The inner wall of the channel is provided with one or more threads, grooves or indentations.

5. The sealing through-flow assembly according to any one of claims 1 to 4, characterized in that: Also includes: Armored sheaths are used to protect optical fibers extending from the low-voltage end through the shaft; or protective sleeves are used to center and align optical fibers and restrict their position at the high-voltage end. Or a combination of the two.

6. A method for winding optical fiber onto an optical fiber spool without pre-twisting, characterized in that: The optical fiber spool includes a core, and the method includes: winding optical fiber from the optical fiber spool to the core to form a first layer of optical fiber; winding optical fiber from the optical fiber spool to the core to form a second layer of optical fiber.

7. The method according to claim 6, characterized in that: It also includes applying an adhesive between the first layer of optical fiber and the second layer of optical fiber.

8. The method according to claim 7, characterized in that: The first layer of optical fiber is wound from the first position to the second position on the core shaft; and the second layer of optical fiber is unwound from the second position to the first position one or more times, so that the grooves of the second layer of optical fiber are aligned with those of the first layer of optical fiber.

9. The method according to claim 8, characterized in that: The first position is a limiting plate used to restrict the axial positioning of the optical fiber, and the second position is the same.

10. The method according to claim 9, characterized in that: The second position is a chamfer, which is used to prevent the first layer of optical fiber from being pulled out of the mandrel when the probe is released and to avoid obstructing the cable laying.

11. The method according to claim 10, characterized in that: It also includes aligning the mandrel with the fiber optic reel, wherein the fiber feed direction from the fiber optic reel and the fiber take-up direction at the mandrel are respectively along the radial tangent of their respective components.

12. The method according to claim 11, characterized in that: The spindle rotates in a first rotation direction and at a first speed to take in the wire; the fiber optic reel rotates in a first rotation direction and at a second speed associated with the first speed to release the wire; and the first speed and the second speed are set based on the radii of the spindle and the fiber optic reel.

13. The method according to claim 12, characterized in that: The first or second layer of optical fiber has the thickness of a single optical fiber.

14. The method according to claim 13, characterized in that: It also includes winding an additional layer of optical fiber, so that the winding steps of the first and second layers of optical fiber are repeated.

15. The method according to claim 14, characterized in that: An adhesive is applied to the additional layer of optical fiber.

16. The method according to claim 15, characterized in that: Adhesive is applied between each layer of optical fibers.

17. The method according to claim 16, characterized in that: The multilayer optical fiber forms an unwound structure at the second position of the core.

18. The method according to claim 17, characterized in that: The unwinding structure is in the shape of an oblique trapezoid.

19. The method according to claim 18, characterized in that: The adhesive is a high-temperature resistant adhesive.

20. The method according to claim 19, characterized in that: The adhesive is applied in the following ways: during the winding process, the optical fiber is passed through the adhesive box to achieve automatic adhesive application; or the adhesive is applied to one or more layers of optical fiber before or after winding.

21. The method according to claim 20, characterized in that: The outer diameter of the optical fiber is 0.6 mm or less.

22. The method according to claim 21, characterized in that: The fiber core diameter is 0.1 mm or less.

23. A probe for deploying optical fibers downhole, characterized in that: The probe includes one or more fiber optic spools, each spool being configured to wind a single fiber optic cable, and each fiber optic cable of the one or more spools being independent of each other; and the one or more spools can be deployed to achieve multi-parameter sensing.

24. The probe according to claim 23, characterized in that: The multiple fiber optic spools can be deployed simultaneously to achieve synchronous multi-parameter sensing.

25. The probe according to claim 24, characterized in that: The plurality of fiber optic spools includes three fiber optic spools.

26. The probe according to claim 25, characterized in that: It also includes a fiber optic pressure gauge, which contains a pressure grating and a temperature compensation grating.

27. The probe according to claim 26, characterized in that: The fiber optic pressure gauge includes: (a) a single-ended fiber optic output structure; and (b) a fiber Bragg grating sensor or a fiber Fabry-Perot sensor.

28. The probe according to claim 27, characterized in that: It also includes a protective casing for protecting the one or more fiber optic spools downhole.

29. The probe according to claim 28, characterized in that: The protective shell accommodates one or more fiber optic spools in a compact array arrangement.

30. The probe according to claim 29, characterized in that: The lower end of the protective shell is provided with a flow guide head, which is used to stabilize or guide the deployment of the probe downhole.

31. The probe according to claim 30, characterized in that: It also includes an upper connector for temporarily securing the probe to a probe deployment device, downhole tool, or other deployment tool.

32. The probe according to claim 31, characterized in that: The optical fiber includes single-mode optical fiber, multimode optical fiber, or engineered optical fiber.

33. The probe according to claim 32, characterized in that: One of the one or more fiber optic spools contains a soluble composition, allowing the probe to be used once downhole.

34. The probe according to claim 33, characterized in that: The multiple parameters include temperature data, pressure data, acoustic data, vibration data, strain data, strain rate data, seismic data, microseismic data, other applicable distributed measurement data, or combinations of the above data.

35. The probe according to any one of claims 23 to 34, characterized in that: The probe is prepared using the method described in any one of claims 6 to 22 for deployment.

36. The probe according to any one of claims 23 to 34, characterized in that: The optical fiber of the probe is inserted through the sealed passage assembly as described in any one of claims 1 to 5.

37. A multi-parameter sensing device for downhole applications, characterized in that: include: The probe is configured to deploy optical fibers downhole for multi-parameter sensing. A sealed pass-through assembly for transitioning the optical fiber from the probe from a high-pressure environment to a low-pressure environment; and a data acquisition device configured to connect to the optical fiber of the probe via the sealed pass-through assembly and for acquiring one or more signals from the optical fiber.

38. The multi-parameter sensing device according to claim 37, characterized in that: It also includes probe deployment devices.

39. The multi-parameter sensing device according to claim 38, characterized in that: The probe deployment device includes: a blowout preventer (BOP) disposed at the wellhead; a blowout preventer head disposed at the top of the BOP and having a pressurization port for pressurizing the interior of the BOP by connecting to an external pressurization device; a release piston disposed inside the BOP for fixing and releasing the probe under pressure; and a pressure relief valve disposed on the BOP for releasing residual pressure inside the BOP tube after deployment.

40. The multi-parameter sensing device according to any one of claims 37 to 39, characterized in that: The sealing through assembly is the sealing through assembly according to any one of claims 1 to 5.

41. The multi-parameter sensing device according to any one of claims 37 to 39, characterized in that: The acquisition device includes a distributed temperature sensor connected to the optical fiber of the probe for acquiring wellbore temperature profiles via multimode optical fiber.

42. The multi-parameter sensing device according to claim 41, characterized in that: The acquisition device includes a distributed fiber optic acoustic vibration analyzer, which is connected to the probe's optical fiber and is used to monitor vibration signals at one or more locations within the wellbore via single-mode optical fiber.

43. The multi-parameter sensing device according to claim 41, characterized in that: The acquisition device includes a distributed fiber optic acoustic vibration analyzer, which is connected to the probe's optical fiber and is used to monitor vibration signals or locate the probe's position via single-mode optical fiber.

44. The multi-parameter sensing device according to claim 41, characterized in that: The acquisition device includes a fiber Bragg grating demodulator, which is connected to the fiber optic pressure gauge of the probe to demodulate the signal from the fiber optic pressure gauge to obtain pressure data.

45. The multi-parameter sensing device according to any one of claims 37 to 39, characterized in that: The probe is the probe described in any one of claims 23 to 34.

46. ​​An optical fiber composition, characterized in that: The composition is soluble in the downhole environment of the well or can be decomposed by other means.

47. The optical fiber composition according to claim 46, characterized in that: The composition is soluble in oil wells, gas wells, carbon capture and storage wells, brine treatment wells, storage wells or other types of wells or downhole environments.

48. An optical fiber, characterized in that: It comprises the optical fiber composition of claim 46 or 47.

49. The optical fiber according to claim 48, characterized in that: The outer diameter of the optical fiber is 0.6 mm or less.

50. The optical fiber according to any one of claims 49, characterized in that: The fiber core diameter is 0.1 mm or less.

51. The optical fiber according to any one of claims 48 to 50, characterized in that: The fiber spool is formed by winding using any one of claims 6 to 22.

52. The optical fiber according to claim 51, characterized in that: The fiber optic spool is housed within the probe according to any one of claims 23 to 34.

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