Spiral optical fiber sensor for geophysical prospecting

Abstract

The present invention discloses a spiral optical fiber sensor for geophysical prospecting, which includes an outer sheath and an inner protective layer, and a spiral winding mechanism is arranged between the two. The spiral winding mechanism includes at least three spiral optical fibers arranged in a circumferential array. A composite support core is arranged inside the inner protective layer. The spiral angle of the spiral optical fiber is 30° to 60°. Among them, the spiral optical fiber is adjusted at 30°, 45°, and 60°, specifically related to communication sensing technology equipment. By adopting the structure of multiple spiral optical fibers wound spirally, the invention uses the spiral angle to enhance the lateral sensitivity of the spiral optical fiber to improve the quality and efficiency of seismic data. And a composite support core is arranged in the inner layer, which is closer to the outer layer than the optical fiber arranged on the central axis, thereby further increasing the sensitivity. Moreover, the spiral angle of the spiral optical fiber can be adjusted through the position where the sensor is arranged to obtain more accurate measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the field of communication sensing technology, and more specifically to a helical fiber optic sensor for geophysical exploration. Background Art

[0002] A geophysical exploration fiber optic sensor utilizes the fluctuations formed by the reflection, absorption, and heat dissipation of light when it encounters the object to be measured during the transmission of light through the optical fiber, and detects the environment by causing changes in the wavelength, intensity, and phase of the light conduction.

[0003] According to the patent number CN110268229B, publication (announcement) date: September 28, 2021, a disclosed fiber optic sensor includes: a central core formed in the center of the optical fiber, and at least one outer peripheral core formed by helically winding around the central core, and the ratio of the effective refractive index of the central core to the effective refractive index of the outer peripheral core is set in such a way that the optical path length difference between the central core and the outer peripheral core becomes smaller than the optical path length difference when the effective refractive indices of the central core and the outer peripheral core are the same.

[0004] In the prior art including the above patent, the light guiding optical fibers in the fiber optic sensor are mostly arranged along the axial direction. When the optical fiber is arranged along the axial direction, the area for receiving the reflected wavelength on the axial side is limited, resulting in weak fluctuations during detection. When dealing with seismic data, the early-arriving small-frequency afterwaves are not easily detected. Summary of the Invention

[0005] The purpose of the present invention is to provide a helical fiber optic sensor for geophysical exploration, aiming to solve the above problems.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A helical fiber optic sensor for geophysical exploration includes an outer sheath and an inner protective layer, and a helical winding mechanism is arranged between the two. The helical winding mechanism includes at least three helical optical fibers arranged in a circumferential array. A composite support core is arranged inside the inner protective layer, and the helical angle of the helical optical fiber is 30° - 60°;

[0007] Among them, the helical optical fiber is adjusted at 30°, 45°, and 60°.

[0008] Preferably, a helical expansion and contraction groove is opened on the outer wall of the outer sheath, and a pulling groove is opened on the inner wall of the inner protective layer. The helical expansion and contraction groove includes the following three working positions:

[0009] The first working position: The helical expansion and contraction groove is driven to stretch and fix to limit the helical optical fiber to 30°;

[0010] The second working position: The helical expansion and contraction groove is not restricted to drive the helical optical fiber to 45°;

[0011] Third working station: The spiral expansion and contraction groove is driven to contract and fix, so as to limit the spiral optical fiber to 60°.

[0012] Preferably, a covering spiral strip is arranged in the spiral expansion and contraction groove, a plurality of docking columns are arranged on the covering spiral strip, and a through hole penetrating the spiral expansion and contraction groove is formed in the outer sheath;

[0013] Wherein, the spiral expansion and contraction groove is driven to switch to the third working station to drive the docking column to insert into the through hole for fixation;

[0014] The covering spiral strip rebounds to drive the spiral expansion and contraction groove to maintain the second working station.

[0015] Preferably, it further includes a spiral filling strip, and elastic buckles corresponding to the docking columns one by one are arranged on the spiral filling strip. The spiral filling strip is driven to be clamped on the spiral expansion and contraction groove to drive the elastic buckles to be clamped on the docking columns, so that the spiral expansion and contraction groove is driven to switch to the first working station.

[0016] Preferably, fitting grooves for restricting the spiral optical fiber are formed on the inner wall of the outer sheath and the outer wall of the inner protection layer.

[0017] Preferably, the composite support core includes a plurality of hard sleeves arranged in a linear array, and telescopic columns inserted into the inner protection layer are arranged in a circumferential array on the hard sleeves.

[0018] Preferably, a stretching part is arranged between the hard sleeves, and the stretching parts correspond to the pulling grooves formed on the inner protection layer one by one.

[0019] Preferably, the hard sleeves are sequentially locked as the spiral expansion and contraction groove switches to the third working station.

[0020] Preferably, a sheath support part is arranged in the hard sleeve. A conical head is arranged at the first end of the sheath support part, and a conical hole facing the second end is formed in the conical head. The sheath support part moves as the spiral expansion and contraction groove switches to the third working station to drive the conical head to be inserted into the conical hole in sequence for locking.

[0021] In the above technical solution, the geophysical exploration spiral optical fiber sensor provided by the present invention has the following beneficial effects: By adopting the structure of multiple spiral optical fibers wound spirally, the spiral angle is used to enhance the lateral sensitivity of the spiral optical fiber to improve the quality and efficiency of seismic data, and a composite support core is arranged on the inner layer, which is closer to the outer layer than the optical fiber arranged on the central axis, thereby further increasing the sensitivity. Moreover, the spiral angle of the spiral optical fiber can be adjusted through the position where the sensor is arranged to obtain more accurate measurement accuracy. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other accompanying drawings can also be obtained based on these drawings.

[0023] Figure 1 Overall schematic diagram provided by the embodiment of the present invention;

[0024] Figure 2 Explosion schematic diagram of the outer sheath, spiral filling strip and adhering spiral strip provided by the embodiment of the present invention;

[0025] Figure 3 For Figure 2 Enlarged schematic diagram at position A in

[0026] Figure 4 Schematic diagram of the outer sheath and inner protective layer provided by the embodiment of the present invention;

[0027] Figure 5 Explosion schematic diagram of the inner protective layer and composite support core provided by the embodiment of the present invention;

[0028] Figure 6 Overall cross-sectional schematic diagram provided by the embodiment of the present invention;

[0029] Figure 7 For Figure 6 Enlarged schematic diagram at position B in

[0030] Figure 8 Schematic diagram of the helix angle of the spiral optical fiber provided by the embodiment of the invention.

[0031] Explanation of reference numerals:

[0032] 1. Outer sheath; 111. Spiral expansion groove; 112. Through hole; 113. Fitting groove; 12. Inner protective layer; 121. Pulling groove; 13. Adhering spiral strip; 131. Docking post; 2. Spiral winding mechanism; 21. Spiral optical fiber; 3. Spiral filling strip; 31. Elastic buckle plate; 4. Composite support core; 41. Hard sleeve; 42. Telescopic column; 43. Tensile part; 44. Sheath support part; 441. Taper hole; 442. Taper head. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0034] As Figure 1-8 shown, a helical fiber optic sensor for geophysical exploration includes an outer sheath 1 and an inner sheath 12, between which a helical winding mechanism 2 is provided. The helical winding mechanism 2 includes at least three helical optical fibers 21 arranged in a circumferential array. A composite support core 4 is provided inside the inner sheath 12. The helical angle of the helical optical fiber 21 is 30° to 60°.

[0035] Among them, the helical optical fiber 21 is adjusted at 30°, 45°, and 60°.

[0036] Specifically, the helical angle of the helical optical fiber 21 is Figure 8 shown. Taking the central axis of the outer sheath 1 and the inner sheath 12 as a reference, the included angle with the inclination direction of the helical optical fiber 21 is 30° to 60°. During use, all the helical optical fibers 21 are adjusted to an angle according to the required detection accuracy and position. The angle can be 30°, 45°, and 60°, so as to increase the lateral sensitivity of the helical optical fiber 21 to improve the quality and efficiency of seismic data. The helical optical fiber 21 on the outer layer is more easily penetrated by light compared with being arranged along the central axis, so it can detect seismic data more sensitively.

[0037] In the above technical solution, by adopting the structure of helically winding multiple helical optical fibers 21, the helical angle is used to enhance the lateral sensitivity of the helical optical fiber 21 to improve the quality and efficiency of seismic data. And a composite support core 4 is arranged on the inner layer, which is closer to the outer layer compared with the optical fiber arranged along the central axis, thereby further increasing the sensitivity. The helical angle of the helical optical fiber 21 can also be adjusted through the set position of the sensor to obtain a more accurate measurement accuracy.

[0038] Further, the helical optical fiber 21 is selected as a bend-insensitive helical fiber. The optical fiber needs to consider the macro-bending loss, and the optical fiber attenuation index at a wavelength of 1550 nm after cabling is ≤1 dB.

[0039] As an embodiment provided by the present invention, a helical expansion slot 111 is opened on the outer wall of the outer sheath 1, and a pulling slot 121 is opened on the inner wall of the inner sheath 12. The helical expansion slot 111 includes the following three working positions:

[0040] The first working position: The helical expansion slot 111 is driven to be stretched and fixed to limit the helical optical fiber 21 to 30°;

[0041] Second working station: The spiral expansion slot 111 is not restricted, so as to drive the spiral optical fiber 21 to be at 45°;

[0042] Third working station: The spiral expansion slot 111 is driven to contract and fix, so as to restrict the spiral optical fiber 21 to be at 60°.

[0043] Specifically, both the spiral expansion slot 111 and the pulling slot 121 are made of elastic materials, so as to realize the pulling of the sensor. Before setting the sensor, switch the working station of the spiral expansion slot 111 as needed, and stretch the sensor by stretching, so that the spiral expansion slot 111 is switched to the first working station and fixed, making the thread angle of the spiral optical fiber 21 30°. At this time, although the spiral optical fiber 21 is still in a threaded state and its lateral sensitivity is improved, the number of spiral optical fibers 21 per unit length is small, which is suitable for being set at positions with high reflection intensity and easy light and sound wave transmission. At positions with medium reflection intensity, switch the spiral expansion slot 111 to the second working station, so as to increase the number of spiral optical fibers 21 per unit length and change the angle of the spiral optical fiber 21, making it easier to detect the transmission of light and sound waves. At positions with low reflection intensity, high density and very difficult light and sound wave transmission, switch the spiral expansion slot 111 to the third working station. At this time, the spiral angle of the spiral optical fiber 21 is restricted to 60°, and at the same time, the spiral expansion slot 111 is driven to contract and fix, so as to increase the number of spiral optical fibers 21 per unit length and achieve the effect of accurate measurement.

[0044] As an embodiment provided by the present invention, a covering spiral strip 13 is arranged in the spiral expansion slot 111, a plurality of docking posts 131 are arranged on the covering spiral strip 13, and a through hole 112 penetrating the spiral expansion slot 111 is opened on the outer sheath 1;

[0045] Among them, the spiral expansion slot 111 is driven to switch to the third working station, so as to drive the docking post 131 to insert into the through hole 112 and fix;

[0046] The covering spiral strip 13 rebounds, driving the spiral expansion slot 111 to maintain the second working station.

[0047] Specifically, a covering spiral strip 13 is arranged in the spiral expansion slot 111. The covering spiral strip 13 is made of elastic plastic and rigid plastic, having good elasticity and certain supporting ability. When the spiral expansion slot 111 is not restricted by external objects, when it is necessary to switch the spiral expansion slot 111 to the third working position, hold the outer sheath 1 and squeeze it, and rotate it slightly, so that the two sides of the spiral expansion slot 111 are fitted together, and the docking post 131 is inserted into the through hole 112 to fix the spiral expansion slot 111 in the third working position. When it is necessary to switch to the second working position, hold the outer sheath 1 and pull it to drive the docking post 131 to decouple from the through hole 112, and then the elasticity of the covering spiral strip 13 drives it to rebound, so as to maintain the second working position of the spiral expansion slot 111.

[0048] When precise measurement is required, hold the outer sheath 1 and squeeze it, and rotate it slightly, so that the two sides of the spiral expansion slot 111 are fitted together, and the docking post 131 is inserted into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°. At the same time, the spiral expansion slot 111 is driven to contract and fixed to increase the number of spiral optical fibers 21 per unit length. When installed at a position with medium reflection intensity, hold the outer sheath 1 and pull it to drive the docking post 131 to decouple from the through hole 112, and then the elasticity of the covering spiral strip 13 drives it to rebound, so as to maintain the second working position of the spiral expansion slot 111. When at a position with high reflection intensity, the outer sheath 1 is driven to stretch and elongate, so that the spiral expansion slot 111 is switched to the first working position and fixed.

[0049] As an embodiment provided by the present invention, it further includes a spiral filling strip 3. Elastic buckles 31 corresponding to the docking posts 131 one by one are arranged on the spiral filling strip 3. The spiral filling strip 3 is driven to be clamped on the spiral expansion slot 111 to drive the elastic buckles 31 to be clamped on the docking posts 131, so that the spiral expansion slot 111 is driven to switch to the first working position.

[0050] Specifically, the spiral filling strip 3 is a rigid plastic strip, and the rigid plastic strip can be provided with foam materials. When it is necessary to switch the spiral expansion slot 111 to the first working position, the elastic buckle 31 on the spiral filling strip 3 is clamped on the docking post 131, and then the spiral filling strip 3 is squeezed into the spiral expansion slot 111 for filling, so as to squeeze the spiral expansion slot 111 and the pulling slot 121 to stretch, so as to change the spiral angle of the spiral optical fiber 21 to 60°. By filling for stretching, the service time can be extended, and it is not easy to be damaged and change the spiral angle.

[0051] When precise measurement is required, hold the outer sheath 1 and squeeze it, and rotate it slightly to make the two sides of the spiral telescopic groove 111 fit together, and insert the docking post 131 into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°. At the same time, the spiral telescopic groove 111 is driven to contract and fix to increase the number of spiral optical fibers 21 per unit length. When at a position with medium reflection intensity at the installation position, hold the outer sheath 1 and pull it to drive the docking post 131 to decouple from the through hole 112, and then the elastic drive of the attached spiral strip 13 causes it to rebound, so as to maintain the second working position of the spiral telescopic groove 111. When at a position with high reflection intensity, snap the elastic buckle 31 on the spiral filling strip 3 onto the docking post 131, and then squeeze the spiral filling strip 3 into the spiral telescopic groove 111 for filling, so as to squeeze and stretch the spiral telescopic groove 111 and the pulling groove 121, so that the spiral telescopic groove 111 switches to the first working position and is fixed.

[0052] Furthermore, fitting grooves 113 for restricting the spiral optical fiber 21 are provided on the inner wall of the outer sheath 1 and the outer wall of the inner protection layer 12.

[0053] Specifically, the two groups of fitting grooves 113 overlap each other to clamp the spiral optical fiber 21. When the outer sheath 1 and the inner protection layer 12 move together, the two groups of fitting grooves 113 remain in fit to clamp the spiral optical fiber 21 to protect the spiral optical fiber 21.

[0054] As an embodiment provided by the present invention, the composite support core 4 includes a plurality of rigid sleeves 41 arranged in a linear array, and the rigid sleeves 41 are provided with telescopic columns 42 inserted into the inner protection layer 12 in a circumferential array.

[0055] Specifically, the rigid sleeves 41 are connected in series to support the inner protection layer 12 to increase the overall pressure resistance of the sensor. The rigid sleeves 41 are provided with telescopic columns 42 inserted into the inner protection layer 12 in a circumferential array. The telescopic columns 42 increase the connection between the composite support core 4 and the inner protection layer 12, and when the inner protection layer 12 and the outer sheath 1 move, drive the rigid sleeves 41 to move together, so as to increase the overall supportability without affecting the expansion and contraction d1 of the outer sheath 1.

[0056] When precise measurement is required, hold the outer sheath 1 and squeeze it, and rotate it slightly to make the two sides of the spiral expansion slot 111 fit together, and insert the docking post 131 into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°. At the same time, the spiral expansion slot 111 is driven to contract and fixed to increase the number of spiral optical fibers 21 per unit length. When at a position with medium reflection intensity at the installation position, hold the outer sheath 1 and pull it to drive the docking post 131 to decouple from the through hole 112, and then the elastic drive of the attached spiral strip 13 causes it to rebound, so as to maintain the second working position of the spiral expansion slot 111. When at a position with high reflection intensity, snap the elastic buckle 31 on the spiral filling strip 3 onto the docking post 131, and then squeeze the spiral filling strip 3 into the spiral expansion slot 111 for filling, so as to squeeze and stretch the spiral expansion slot 111 and the pulling slot 121, so that the spiral expansion slot 111 switches to the first working position and is fixed. During the process of the spiral expansion slot 111 switching working positions, the rigid sleeve 41 will slide accordingly to maintain the supportability.

[0057] Furthermore, a stretching part 43 is arranged between the rigid sleeves 41. The stretching part 43 is made of elastic plastic and corresponds one-to-one with the pulling slots 121 opened on the inner protective layer 12. Thus, when the inner protective layer 12 is stretched or contracted, the stretching part 43 is driven to move together. The stretching part 43 increases the tensile capacity of the overall sensor and stretches and contracts with the switching of the working position of the spiral expansion slot 111, so as to realize the telescopic capacity of the overall sensor.

[0058] As the optimal embodiment provided by the present invention, the rigid sleeves 41 are sequentially locked as the spiral expansion slot 111 switches to the third working position;

[0059] A sheath support part 44 is arranged inside the rigid sleeve 41. A conical head 442 is arranged at the first end of the sheath support part 44, and a conical hole 441 facing the second end is opened on the conical head 442. The sheath support part 44 moves as the spiral expansion slot 111 switches to the third working position to drive the conical head 442 to be inserted into the conical hole 441 in sequence for locking.

[0060] Specifically, a sheath support part 44 is arranged inside the rigid sleeve 41. The sheath support part 44 is used to increase the compressive capacity of the overall sensor to Figure 7As shown, the first end is the upper end and the second end is the lower end. A tapered head 442 is provided at the first end of the sheath support portion 44. A tapered hole 441 facing the second end is formed in the tapered head 442. The circular cross-section of the tapered hole 441 is larger than that of the tapered head 442. Thus, when the spiral expansion and contraction groove 111 switches to the third working position, it drives the hard sleeve 41 to slide, so that the tapered head 442 is inserted into the connected tapered hole 441, and is locked by the taper. After locking, the connected tapered head 442 and tapered hole 441 are fixed to each other and cannot be opened from the middle, increasing the consistency. Thus, in the case where the geology is likely to change, the third working position is adopted to reinforce the overall sensor. At the same time, the mutually locked tapered head 442 and tapered hole 441 will also limit the bending angle of the whole, protecting the spiral optical fiber 21.

[0061] Furthermore, a small-sized ring is provided in the middle of the stretching portion 43. The small-sized ring is made of hard plastic. When the overall sensor is in the first working position or the second working position and is bent during the layout process, the tapered head 442 is not inserted into the tapered hole 441. During the bending process, the tapered head 442 will rotate and move. The greater the bending amplitude, the greater the moving range. And during the bending process, due to the tapered head 442 being restricted by the small-sized ring, the bending angle is limited, so that the maximum bending angle of the local sensor is restricted, thus avoiding the spiral optical fiber 21 of the spiral from breaking or losing the light guiding ability due to too large a bending angle.

[0062] When precise measurement is required, hold the outer sheath 1 and squeeze it, and perform a small rotation to make the two sides of the spiral expansion and contraction groove 111 fit together, and make the docking post 131 insert into the through hole 112. At this time, the spiral angle of the spiral optical fiber 21 is limited to 60°. At the same time, the spiral expansion and contraction groove 111 is driven to contract and fix, so as to increase the number of spiral optical fibers 21 per unit length, and slide along with the hard sleeve 41, so that the tapered head 442 is inserted into the connected tapered hole 441, and is locked by the taper. When at a position with medium reflection intensity during installation, hold the outer sheath 1 and pull it, driving the docking post 131 to decouple from the through hole 112, and then the elastic force of the attached spiral strip 13 drives it to rebound, so as to maintain the second working position of the spiral expansion and contraction groove 111. When at a position with high reflection intensity, the elastic buckle 31 on the spiral filling strip 3 is snapped onto the docking post 131, and then the spiral filling strip 3 is squeezed into the spiral expansion and contraction groove 111 for filling, so as to squeeze the spiral expansion and contraction groove 111 and the stretching groove 121 for stretching, so that the spiral expansion and contraction groove 111 switches to the first working position for fixing. During the process of the spiral expansion and contraction groove 111 switching working positions, the hard sleeve 41 will slide along with it. In the spiral expansion and contraction groove 111 in the first and second working positions, during the underground layout process, the tapered head 442 will be restricted by the small-sized ring on the stretching portion 43, thus restricting the maximum bending angle and protecting the sensor.

[0063] Only some exemplary embodiments of the present invention have been described by way of illustration. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A helical optical fiber sensor for geophysical exploration, characterized in that, It includes an outer sheath and an inner sheath, and a spiral winding mechanism is arranged between the two. The spiral winding mechanism includes at least three spiral optical fibers arranged in a circumferential array. A composite support core is arranged in the inner sheath. The spiral angle of the spiral optical fiber is 30° to 60°; Among them, the spiral optical fiber is adjusted at 30°, 45° and 60°; A spiral expansion groove is formed on the outer wall of the outer sheath, and a pulling groove is formed on the inner wall of the inner sheath. The spiral expansion groove includes the following three working positions: The first working position: The spiral expansion groove is driven to stretch and fixed to limit the spiral optical fiber to 30°; The second working position: The spiral expansion groove is not restricted to drive the spiral optical fiber to 45°; The third working position: The spiral expansion groove is driven to contract and fixed to limit the spiral optical fiber to 60°; A covering spiral strip is arranged in the spiral expansion groove. A number of docking columns are arranged on the covering spiral strip. A through hole penetrating the spiral expansion groove is formed on the outer sheath; Among them, the spiral expansion groove is driven to switch to the third working position to drive the docking column to insert into the through hole for fixing; The covering spiral strip rebounds to drive the spiral expansion groove to maintain the second working position; It also includes a spiral filling strip. Elastic buckles corresponding to the docking columns one by one are arranged on the spiral filling strip. The spiral filling strip is driven to be clamped on the spiral expansion groove to drive the elastic buckles to be clamped on the docking columns, so that the spiral expansion groove is driven to switch to the first working position; The composite support core includes a plurality of hard sleeves arranged in a linear array. The hard sleeves are arranged in a circumferential array with telescopic columns inserted into the inner sheath; A stretching part is arranged between the hard sleeves, and the stretching part corresponds to the pulling groove formed on the inner sheath one by one.

2. The fiber optic helical sensor for geophysical prospecting according to claim 1, characterized in that, Coincidence grooves for restricting the spiral optical fiber are formed on both the inner wall of the outer sheath and the outer wall of the inner sheath.

3. The geophysical exploration spiral optical fiber sensor according to claim 1, characterized in that, The hard sleeves are locked in sequence as the spiral expansion groove switches to the third working position.

4. The helical optical fiber sensor for geophysical prospecting according to claim 3, characterized in that, A sheath support part is arranged in the hard sleeve. A conical head is arranged at the first end of the sheath support part. A conical hole facing the second end is formed on the conical head. The sheath support part moves as the spiral expansion groove switches to the third working position to drive the conical head to be inserted into the conical hole in sequence for locking.

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