Fiber bragg grating temperature and pressure sensor

Abstract

The invention provides a fiber bragg grating temperature and pressure sensor, and relates to the technical field of oil and gas well detection. The fiber bragg grating temperature and pressure sensor comprises a sensor base, a supporting assembly and a detection assembly, the sensor base is provided with a first supporting piece and two second supporting pieces, the first supporting piece is located between the two second supporting pieces, the connecting pieces are hinged to the second supporting pieces in a one-to-one correspondence mode, and the two connecting pieces are both hinged to the first supporting piece; the optical fiber is provided with a first grating and a second grating, one of the two connecting pieces is provided with a heat conduction expansion part, the two connecting pieces are connected with the optical fiber, the first grating is located between the two connecting pieces, and the second grating is located on the heat conduction expansion part. The fiber bragg grating temperature and pressure sensor provided by the invention is simple in structure, can realize simultaneous measurement of temperature and pressure, and is high in integration level; the support assembly forms a scissor-shaped hinge structure to reflect the deformation of the pressure on the sensor base, the overall stability is good, and the sensitivity of pressure measurement is more accurate.

Description

Technical Field

[0001] This application relates to the field of oil and gas well detection technology, and in particular to a fiber optic grating temperature and pressure sensor. Background Technology

[0002] Monitoring parameters such as downhole temperature, pressure, and flow rate during oilfield exploration and production is an important means to improve the ultimate recovery rate of oil and gas fields and to develop them scientifically and rationally.

[0003] In related technologies, downhole oil and gas wells typically use thermistor temperature sensors, such as PT10, PT20, Pt100, and Pt1000, to detect temperature, and 0.1‰ strain gauge pressure sensors to detect pressure.

[0004] However, the temperature and pressure sensors mentioned above are independent, large in size and complex in structure, which is not conducive to the miniaturization design of downhole annular fluid production profilers for oil and gas wells; and the temperature resistance of the pressure sensor cannot meet the requirements of ultra-deep wells, and its stability is poor. Summary of the Invention

[0005] This application provides a fiber Bragg grating temperature and pressure sensor to address the shortcomings of related technologies.

[0006] This application provides a fiber Bragg grating temperature and pressure sensor, including a sensor base, a support assembly, and a detection assembly. The sensor base is used to connect to the pressure measuring hole of an oil and gas well. A pressure inlet groove is formed on the sensor base. The support assembly includes a first support member, two second support members, and two connecting members. The first support member and the two second support members are all disposed on the sensor base, with the first support member located between the two second support members. The connecting members and the second support members are hinged one-to-one, and both connecting members are hinged to the first support members. The detection assembly includes an optical fiber and a first grating and a second grating disposed on the optical fiber. Both connecting members are connected to the optical fiber, with the first grating located between the two connecting members. One of the two connecting members is provided with a thermally conductive expansion portion, and the second grating is located on the thermally conductive expansion portion. The sensor base is configured to deform when pressurized in the pressure inlet groove. The two second support members are used to move relative to the first support member when the sensor base deforms, thereby driving the corresponding connecting members to rotate toward the sensor base, causing the two connecting members to move in opposite directions.

[0007] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment has a cylindrical sensor base, the axis of the first support member coincides with the axis of the sensor base, and two second support members are symmetrically arranged on opposite sides of the first support member, with each second support member corresponding to a pressure inlet groove.

[0008] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment has a distance between the wall of the pressure inlet groove and the side wall of the adjacent sensor base that is greater than or equal to the distance between the bottom of the pressure inlet groove and the side of the sensor base away from the opening of the pressure inlet groove; wherein, the distance between the bottom of the pressure inlet groove and the side of the sensor base away from the opening of the pressure inlet groove is 1mm-3mm.

[0009] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment has a second support member whose length along the axial direction of the sensor base is less than the length of the first support member along the axial direction of the sensor base.

[0010] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment has a connector including a connecting part, which is sequentially hinged to the end of the second support member away from the sensor base and the end of the first support member away from the sensor base; the connecting part has a connecting surface, the optical fiber is connected to the connecting surface, the thermal conductivity expansion part is connected to the connecting part, and the side of the thermal conductivity expansion part away from the sensor base is flush with the connecting surface.

[0011] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment further includes a first hinge member, a first insertion groove is provided on the first support member, and a portion of the connecting part is inserted into the first insertion groove; a sliding hole is provided on the connecting part, and two first insertion holes communicating with the first insertion groove are provided on the groove wall of the first insertion groove. The first hinge member passes through one of the two first insertion holes, the sliding hole and the other of the two first insertion holes in sequence, so that the connecting part is hinged to the first support member.

[0012] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment further includes two second hinge members, each corresponding to a connecting portion. A second insertion slot is provided on the second support member, and a portion of the connecting portion is inserted into the second insertion slot. A connecting hole is provided on the connecting portion, and two second insertion holes communicating with the second insertion slot are provided on the groove wall of the second insertion slot. The second hinge member passes through one of the two second insertion holes, the connecting hole, and the other of the two second insertion holes in sequence, so that the connecting portion is hinged to the second support member.

[0013] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment includes a connecting portion comprising a first insertion segment, a first support segment, a second insertion segment, and a second support segment connected in sequence; a connecting hole is located on the first insertion segment, a sliding hole is located on the second insertion segment, and a connecting surface is provided on the second support segment; the distance between the center of the connecting hole and the center of the sliding hole is less than the distance between the center of the sliding hole and the connecting surface.

[0014] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment uses a single-mode fiber with a polyimide coating.

[0015] In one possible implementation, the fiber optic temperature and pressure sensor provided in this application embodiment has a first grating with a grating region length of 1mm-5mm, and a second grating with a grating region length equal to that of the first grating; the difference between the center wavelength of the first grating and the center wavelength of the second grating is ≥3nm.

[0016] The fiber Bragg grating temperature and pressure sensor provided in this application comprises a first support member and two second supports members arranged on a sensor base, with the first support member positioned between the two second supports members. Connecting members are provided and hinged to the second supports members one-to-one, with both connecting members hinged to the first supports members. A first grating and a second grating are arranged on an optical fiber, and a thermally conductive expansion portion is provided on one of the two connecting members. By connecting both connecting members to the optical fiber, the first grating is positioned between the two connecting members, and the second grating is positioned on the thermally conductive expansion portion. Thus, when detecting the pressure downhole in an oil or gas well, the sensor base is connected to the pressure measuring port of the oil or gas well, and a pressure inlet groove is formed on the sensor base, thereby... When liquid or gas enters the pressure inlet groove, the groove deforms under pressure, causing two second support members to move relative to the first support member. This deformation drives the corresponding connecting members to rotate towards the sensor base, which in turn causes the two connecting members to move in opposite directions, thus stretching the first grating to detect the pressure. Furthermore, the thermal expansion section, affected by the oil and gas well temperature, allows the second grating located thereon to detect the temperature. The fiber optic grating temperature and pressure sensor provided in this application has a simple structure, can simultaneously measure temperature and pressure, and has high integration. The scissor-type hinge structure formed by the support components reflects the deformation of the sensor base caused by pressure, resulting in good overall stability and more accurate pressure measurement sensitivity. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figure 1 This is a schematic diagram of the structure of the fiber Bragg grating temperature and pressure sensor provided in the embodiments of this application;

[0019] Figure 2 The connection between the sensor base, the first support member, and the second support member provided in the embodiments of this application Figure 1 ;

[0020] Figure 3 The connection between the sensor base, the first support member, and the second support member provided in the embodiments of this application Figure 2 ;

[0021] Figure 4 for Figure 1 A sectional view;

[0022] Figure 5 Another structural cross-sectional view of the fiber optic temperature and pressure sensor provided in the embodiments of this application;

[0023] Figure 6 A schematic diagram of the structure of the first hinge in the fiber optic temperature and pressure sensor provided in this embodiment of the application;

[0024] Figure 7 A schematic diagram of the structure of the first support member in the fiber optic temperature and pressure sensor provided in an embodiment of this application;

[0025] Figure 8 A schematic diagram of the structure of the second support member in the fiber optic temperature and pressure sensor provided in the embodiment of this application;

[0026] Figure 9 This is a schematic diagram of the connector in the fiber optic temperature and pressure sensor provided in an embodiment of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100 - Sensor base;

[0029] 101 - Base body; 102 - Pressure sensitive element; 110 - Pressure inlet groove; 120 - Threaded interface;

[0030] 200 - Support components;

[0031] 210 - First support member; 220 - Second support member; 230 - Connector;

[0032] 211-First insertion slot; 212-First insertion hole; 221-Second insertion slot; 222-Second insertion hole; 231-Thermal conduction expansion part; 232-Connecting part; 233-Connecting surface;

[0033] 2321 - First insertion section; 2322 - First support section; 2323 - Second insertion section; 2324 - Second support section; 2325 - Sliding hole; 2326 - Connecting hole;

[0034] 300 - Detection Components;

[0035] 310 - Optical fiber; 320 - First grating; 330 - Second grating;

[0036] 400 - First hinge; 500 - Second hinge;

[0037] 410 - Contact part; 420 - Hinge part. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] The terms "first," "second," "third," "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those illustrated or described herein.

[0042] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0043] As mentioned in the background section, in related technologies, downhole oil and gas wells typically use thermistor temperature sensors, such as PT10, PT20, Pt100, and Pt1000, to detect temperature, and 0.1‰ strain gauge pressure sensors to detect pressure.

[0044] However, the temperature and pressure sensors mentioned above are independent, large in size and complex in structure, which is not conducive to the miniaturization design of downhole annular fluid production profilers for oil and gas wells; and the temperature resistance of the pressure sensor cannot meet the requirements of ultra-deep wells, and its stability is poor.

[0045] In view of this, embodiments of this application provide a fiber Bragg grating temperature and pressure sensor. A first support member and two second support members are provided on the sensor base, with the first support member positioned between the two second support members. Connectors are provided and hinged to the second support members one-to-one, and both connectors are hinged to the first support member. A first grating and a second grating are provided on the optical fiber, and a thermally conductive expansion portion is provided on one of the two connectors. By connecting both connectors to the optical fiber, the first grating is positioned between the two connectors, and the second grating is positioned on the thermally conductive expansion portion.

[0046] Thus, when detecting pressure downhole in oil and gas wells, the sensor base is connected to the pressure measuring port of the oil and gas well, and a pressure inlet groove is opened on the sensor base. When liquid or gas enters the pressure inlet groove, the groove deforms under pressure, causing the two second support members to move relative to the first support member under deformation. This causes the corresponding connecting member to rotate towards the sensor base, and then the two connecting members move in opposite directions, so that the first grating is stretched to detect the pressure. In addition, the thermal expansion part is affected by the temperature of the oil and gas well, so that the second grating located on it can detect the temperature. The fiber optic grating temperature and pressure sensor provided in this application has a simple structure, can achieve simultaneous temperature and pressure measurement, and has a high degree of integration. The scissor-type hinge structure formed by the support components reflects the deformation of the sensor base caused by pressure, has good overall stability, and makes the pressure measurement more accurate.

[0047] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0048] See Figures 1 to 3The fiber optic temperature and pressure sensor provided in this application includes a sensor base 100, a support assembly 200, and a detection assembly 300. The sensor base 100 is used to connect to the pressure measuring hole of an oil and gas well. A pressure inlet groove 110 is provided on the sensor base 100. The support assembly 200 includes a first support member 210, two second support members 220, and two connecting members 230. The first support member 210 and the two second support members 220 are all disposed on the sensor base 100, and the first support member 210 is located between the two second support members 220. The connecting members 230 and the second support members 220 are hinged one-to-one, and both connecting members 230 are hinged to the first support member 210.

[0049] The detection assembly 300 includes an optical fiber 310 and a first grating 320 and a second grating 330 disposed on the optical fiber 310. Both connectors 230 are connected to the optical fiber 310. The first grating 320 is located between the two connectors 230. One of the two connectors 230 is provided with a thermally conductive expansion portion 231, and the second grating 330 is located on the thermally conductive expansion portion 231. The sensor base 100 is configured to deform when pressed in the pressure groove 110. Two second supports 220 are used to move relative to the first support 210 when the sensor base 100 deforms, so as to drive the corresponding connectors 230 to rotate toward the sensor base 100, so that the two connectors 230 move in opposite directions.

[0050] Specifically, the sensor base 100 serves as the foundation of the entire fiber optic temperature and pressure sensor and is used to connect to the pressure measurement port of the oil and gas well to ensure positioning and stability during the detection process.

[0051] For example, by creating a pressure inlet groove 110 on the sensor base 100, the pressure inlet groove 110 serves as an opening or channel on the sensor base 100, allowing external pressure such as liquid or gas to enter and causing deformation of the sensor base 100. When the pressure inside the well changes, the sensor base 100 deforms due to the pressure, affecting the first support member 210 installed on it, causing displacement of the first support member 210. In a specific implementation, the sensor base 100 may include a pressure-sensitive element 102 and a base body 101 arranged sequentially. The support assembly 200 is used to be installed on the pressure-sensitive element 102, and the base body 101 is used to connect to the pressure measuring hole. The base body 101 can be made of high-strength, corrosion-resistant materials such as stainless steel or titanium alloy to adapt to the oil and gas well environment.

[0052] In order to enable the second support member 220 to move relative to the first support member 210 when the pressure groove 110 is under pressure, the pressure sensitive member 102 that generates deformation can be structurally designed according to the arrangement of the pressure groove 110 and the first support member 210 and the second support member 220 connected thereto.

[0053] Specifically, combined Figure 2 As shown, the pressure-sensitive element 102 and the base body 101 are arranged from top to bottom along the Z direction as shown in the figure. A pressure inlet groove 110 extending to the pressure-sensitive element 102 is opened on the base body 101. The first support member 210 and the second support member 220 located on the pressure-sensitive element 102 are opposite to the pressure inlet groove 110. At this time, the pressure-sensitive element 102 in the area where the two second support members 220 are located can be made of a corrosion-resistant material with good elasticity and stress-strain characteristics, such as an elastic diaphragm or carbon fiber, while the pressure-sensitive element 102 in the area where the first support member 210 is located is made of a material with low elasticity and high stiffness. In this way, when the liquid or gas in the oil and gas well enters the pressure inlet groove 110 through the groove opening and flows upward along the Z direction to impact the pressure-sensitive element 102, because different areas on the pressure-sensitive element 102 have different elastic moduli, only the pressure-sensitive elements 102 in the area where the two second support members 220 are located deform, so that the two will move upward along the Z direction relative to the first support member 210.

[0054] Of course, the number of pressure grooves 110 opened on the base body 101 can also be set as follows: Figure 3 As shown in the two figures, the pressure-sensitive element 102 and the base body 101 are arranged from top to bottom along the Z direction as illustrated. Both pressure inlet grooves 110 are formed on the base body 101 and the pressure-sensitive element 102. That is, the pressure inlet groove 110 penetrates the base body 101 and extends further towards the pressure-sensitive element 102, such that a portion of the pressure inlet groove 110 structure is located on the pressure-sensitive element 102. Overall, one of the second support members 220, one of the pressure inlet grooves 110, the first support member 210, the other of the pressure inlet groove 110, and the other of the second support member 220 are spaced apart from left to right along the X direction as illustrated.

[0055] It should be noted that the portion of the pressure-sensitive element 102 located between the two pressure inlet grooves 110, i.e., the area opposite to the first support member 210, can be made of a material with low elasticity and high stiffness, as mentioned earlier. The remaining portion of the pressure-sensitive element 102 can be made of an elastic diaphragm or other corrosion-resistant material with good elasticity and stress-strain characteristics. Alternatively, the pressure-sensitive element 102 can be a single elastic diaphragm, and the distance between the two pressure inlet grooves 110 can be greater than the distance between the pressure inlet groove 110 and the sidewall of the adjacent base body 101. It is understood that elastic diaphragms are typically made of polymers or similar materials and have good elasticity and stress-strain characteristics. When subjected to pressure, the diaphragm deforms.

[0056] With this configuration, when liquid or gas in the oil and gas well enters the pressure inlet 110 through the inlet and flows upward in the Z direction to impact the pressure sensor 102, it can be ensured that the fluid in the left pressure inlet 110 will generate a large leftward impact force on the pressure sensor 102, and the fluid in the right pressure inlet 110 will generate a large rightward impact force on the pressure sensor 102. Since the pressure sensor 102 at these two locations is prone to deformation, the second support member 220 on the left will move to the left relative to the first support member 210 to adapt to the deformation of the pressure sensor 102 on the left; similarly, the second support member 220 on the right will move to the right relative to the first support member 210 to adapt to the deformation of the pressure sensor 102 on the right.

[0057] In a specific implementation, the connector 230 is hinged to the second support 220 in a one-to-one correspondence, and both connectors 230 are hinged to the first support 210; a first grating 320 and a second grating 330 are provided on the optical fiber 310, and a thermal conductivity expansion part 231 is provided on one of the two connectors 230. By connecting both connectors 230 to the optical fiber 310, the first grating 320 is located between the two connectors 230 and the second grating 330 is located on the thermal conductivity expansion part 231.

[0058] Overall, when detecting the pressure and temperature downhole in oil and gas wells, liquid or gas enters the pressure inlet groove 110, causing it to be pressurized. The pressure inlet groove 110 deforms under this pressure, causing the two second support members 220 to move relative to the first support member 210. This causes the corresponding connecting member 230 to rotate towards the sensor base 100, which in turn causes the two connecting members 230 to move in opposite directions, thus pulling the first grating 320 to detect the pressure. Furthermore, the thermal expansion section 231, affected by the oil and gas well temperature, allows the second grating 330 located on it to detect the temperature. The fiber optic temperature and pressure sensor provided in this application has a simple structure, can simultaneously measure temperature and pressure, and has high integration. It also exhibits good overall stability. The support assembly 200 forms a scissor-type hinge structure to reflect the deformation of the sensor base 100 caused by pressure, resulting in good overall stability and more accurate pressure measurement sensitivity.

[0059] Here, as mentioned earlier, it can be understood that the movement of the two second support members 220 relative to the first support member 210 under deformation can be either both second support members 220 moving upwards relative to the first support member 210, or both second support members 220 moving in opposite directions, i.e., moving away from the first support member 210. Overall, since the support assembly 200 forms a movable structure through hinges, it can achieve a positional change in the first grating 320 on the optical fiber 310 caused by tension via the connector 230. In this way, pressure changes are converted into changes in the position of the grating in the optical fiber 310, thereby altering the reflected wavelength of the first grating 320, realizing the conversion of pressure signals into optical signals. Simultaneously, the linkage of the mechanical structure ensures the reliability and stability of the conversion process.

[0060] For example, the first grating 320 in this application embodiment is an fiber optic 310 Bragg grating (FBG). For the fiber optic 310 Bragg grating (FBG), there are...

[0061] λ B =2n eff Λ 1

[0062] Here λ B Often referred to as the Bragg wavelength, also known as the initial resonant wavelength; n eff Λ is the effective refractive index of the fiber core of fiber 310; Λ is the period of the uniform fiber 310 grating.

[0063] FBG sensing technology utilizes the characteristic that the Bragg wavelength changes with the external environment. Furthermore, it can be determined that the wavelength shift of FBG under the influence of temperature and strain is as follows:

[0064] Δλ B =(α+ξ)λ B ΔT+(1-p e )λ B ε2

[0065] In the formula, α is the thermal expansion coefficient of optical fiber 310, ξ is the thermo-optic coefficient of optical fiber 310, ΔT is the change in ambient temperature, and P e ε is the effective elastic-optic coefficient of optical fiber 310, and ε is the axial strain of optical fiber 310.

[0066] When the fiber optic temperature and pressure sensor is placed in a high-temperature and high-pressure environment, liquid or gas enters the pressure inlet 110, causing the sensor base 100 to deform. As mentioned earlier, the first grating 320 is stretched, and the center wavelength increases.

[0067] Ambient temperature also affects the first grating 320. If the temperature increases, the wavelength of the first grating 320 also increases. If the temperature decreases, the wavelength of the first grating 320 also decreases. Ultimately, the wavelength of the first grating 320 is the result of the combined effects of pressure and temperature. Its wavelength change can be expressed as...

[0068] Δλ 11 =[(ξ+α)+(1-P eff )ε T ]·ΔT·λ 11 +(1-P eff )ε P ·λ 11 (3)

[0069] In the formula, λ 11 ε is the Bragg wavelength of the first grating 320. T ε is the strain of the first grating 320 caused by the thermal expansion of the sensor structure. P The strain of the first grating 320 caused by pressure.

[0070] Since the two ends of the second grating 330 are located on the thermally conductive expansion portion 231, it is not affected by strain caused by pressure changes, but only by ambient temperature, exhibiting good monotonicity. The thermally conductive expansion portion 231 can be made of a metal material with good thermal conductivity, possessing the characteristic of thermal expansion and contraction. When the ambient temperature rises, the volume of the thermally conductive expansion portion 231 expands, simultaneously pulling the second grating 330 located on it to extend. At this time, the period Λ of the second grating 330 increases, and the center wavelength increases. The ambient temperature corresponds one-to-one with the extension amount of the second grating 330, exhibiting a good monotonic relationship. Its wavelength change can be expressed as...

[0071] Δλ 12 =(ξ+α)λ 12 ΔT (4)

[0072] In the formula, λ 12 The Bragg wavelength of the second grating 330.

[0073] In this way, the change in ambient temperature ΔT can be accurately measured by the change in wavelength of the second grating 330. Substituting ΔT into equation (3) eliminates the influence of ambient temperature on the first grating 320, leaving only the influence of pressure, thereby realizing pressure measurement by utilizing the correspondence between the wavelength of the first grating 320 and the pressure.

[0074] In practice, a sealing structure can be provided on the peripheral edge of the sensor base 100 to ensure that there is no leakage in the high-pressure environment of the oil and gas well.

[0075] In addition, the sensor base 100 is provided with a connection interface, such as a threaded interface 120 or a flange, that matches the pressure measurement hole of the oil and gas well to facilitate the installation and removal of the fiber optic temperature and pressure sensor.

[0076] See Figure 1 and Figure 4 In some embodiments, the sensor base 100 is cylindrical, the axis of the first support member 210 coincides with the axis of the sensor base 100, and two second support members 220 are symmetrically arranged on opposite sides of the first support member 210. The second support members 220 correspond one-to-one with the pressure groove 110.

[0077] Specifically, the cylindrical sensor base 100 design and the symmetrical arrangement of the second support member 220 can ensure that the sensor base 100 is subjected to balanced force when under pressure, reduce the risk of local overload, and help improve the accuracy and repeatability of the measurement. In addition, it can facilitate the connection between the sensor base 100 and the pressure measuring hole of the oil and gas well, and improve the stability and reliability of the overall structure.

[0078] By setting the axis of the first support member 210 to coincide with the axis of the base, and making the second support member 220 correspond one-to-one with the pressure inlet groove 110, it is ensured that pressure changes can be accurately converted into displacement of the second support member 220, so that pressure changes can be more efficiently converted into position changes of the first grating 320. Overall, the mechanical linkage structure formed by the support assembly 200 and the response characteristics of the measuring assembly are optimized, improving measurement accuracy and dynamic performance.

[0079] Here, as mentioned earlier, the sensor base 100 includes a pressure-sensitive element 102 and a base body 101 arranged sequentially. Through this arrangement, the pressure-sensitive element 102 can be configured as a single elastic diaphragm, thereby optimizing the structure of the sensor base 100 and making its structure more streamlined. For example, in conjunction with... Figure 4 As shown, when liquid or gas in an oil and gas well enters the pressure inlet groove 110 through the groove opening and flows upward in the Z direction to impact the pressure sensing element 102, since the second support 220 on the pressure sensing element 102 corresponds one-to-one with the pressure inlet groove 110, the two second support 220 can be directly affected by the deformation of the pressure sensing element 102 due to pressure. As a result, under the action of the impact force, they move relative to the first support 210 in a direction away from the sensor base 100, thereby causing the corresponding hinged connecting piece 230 to rotate toward the sensor base 100. The opposite movement of the two connecting pieces 230 will cause the first grating 320 to be stretched, thus realizing the detection of pressure.

[0080] See Figure 4In some examples, the distance between the wall of the pressure inlet groove 110 and the side wall of the adjacent sensor base 100 is greater than or equal to the distance between the bottom of the pressure inlet groove 110 and the side of the sensor base 100 away from the opening of the pressure inlet groove 110; wherein, the distance between the bottom of the pressure inlet groove 110 and the side of the sensor base 100 away from the opening of the pressure inlet groove 110 is 1mm-3mm.

[0081] In this way, as the liquid or gas in the oil and gas well flows through the opening of the pressure inlet 110 into the pressure inlet 110, it can be ensured that the pressure generated by the liquid or gas can be effectively transmitted from the opening to the bottom of the tank, reducing the loss during the pressure transmission process.

[0082] It is understandable that, since the second support member 220 corresponds one-to-one with the pressure inlet groove 110, when the bottom of the pressure inlet groove 110 is compressed and deformed, it will push the corresponding second support member 220 to move. By reflecting the pressure signal more completely on the deformation of the bottom of the pressure inlet groove 110, the response speed and signal fidelity of the fiber optic temperature and pressure sensor are enhanced.

[0083] The distance between the bottom of the pressure inlet groove 110 and the side of the sensor base 100 away from the opening of the pressure inlet groove 110 is 1mm-3mm, so as to balance the stability of the structure and the sensitivity of pressure sensing, and ensure that the sensor can maintain good response characteristics when subjected to high pressure.

[0084] For example, in a specific implementation, the distance can be set to 3mm. This setting ensures both the pressure sensing sensitivity and the rigidity of the pressure inlet groove 110 structure, preventing structural failure caused by excessive deformation. This contributes to the structural stability and durability of the sensor base 100, extending the sensor's service life.

[0085] It should be noted that by designing the distance between the bottom of the pressure inlet groove 110 and the side of the sensor base 100 away from the opening of the pressure inlet groove 110, it can be ensured that the deformation and pressure have a linear relationship, which facilitates the accurate measurement of pressure and temperature.

[0086] See Figures 1 to 4 In a specific example, the length of the second support member 220 along the axis of the sensor base 100 is less than the length of the first support member 210 along the axis of the sensor base 100.

[0087] With this configuration, after the connector 230 and the second support 220 are hinged one-to-one, and each connector 230 is hinged to the first support 210, the two connectors 230 can cross to form an X-shaped structure, which facilitates the rotation of the connector 230 toward the sensor base 100, making the movement of the connector 230 smoother. Overall, this ensures that the support assembly 200 is constructed as a scissor-type hinge structure.

[0088] In specific implementation, both the first support member 210 and the second support member 220 can be configured as follows: Figure 1 The rod-shaped structure shown can be configured as either a column or a rod with a square cross-section, as long as the structure of the first support member 210 and the second support member 220 is regular and easy to manufacture. This application does not impose any limitations on this embodiment.

[0089] See Figure 4 and Figure 5 In some embodiments, the connector 230 includes a connecting portion 232, which is hinged to the end of the second support member 220 away from the sensor base 100 and the end of the first support member 210 away from the sensor base 100 in sequence; the connecting portion 232 has a connecting surface 233, the optical fiber 310 is connected to the connecting surface 233, the thermally conductive expansion portion 231 is connected to the connecting portion 232, and the side of the thermally conductive expansion portion 231 away from the sensor base 100 is flush with the connecting surface 233.

[0090] Specifically, by hinged to the end of the second support member 220 away from the sensor base 100 and the end of the first support member 210 away from the sensor base 100 in sequence, the displacement of the second support member 220 relative to the first support member 210 can be smoothly transmitted to the connecting part 232, so that the two connecting parts 232 move in opposite directions, ensuring that the pressure change can be accurately converted into the position change of the first grating 320, thereby improving the detection sensitivity and measurement accuracy.

[0091] The connecting surface 233 is used to provide a connection point and support for the optical fiber 310. By connecting the optical fiber 310 to the connecting surface 233, the optical fiber 310 can be glued to the two connecting surfaces 233 to ensure that the optical fiber 310 can be firmly fixed on the connector 230, avoiding unnecessary movement or vibration of the optical fiber 310. This can reduce noise during signal transmission and improve the stability of detection.

[0092] By setting the side of the thermally conductive expansion part 231 away from the sensor base 100 to be flush with the connecting surface 233, when the optical fiber 310 is bonded to the connecting surface 233, the second grating 330 can directly contact the thermally conductive expansion part 231. In this way, when the thermally conductive expansion part 231 expands in volume due to temperature rise, the second grating 330 can be pulled to extend in time, which helps to improve the response speed and accuracy of temperature measurement and ensure the stable performance of the sensor under temperature change environment.

[0093] It should be noted that, in the specific implementation, such as Figure 5As shown, one of the two connectors 230 is provided with a thermal expansion portion 231, and the second optical fiber 310 is correspondingly disposed on the thermal expansion portion 231. The thermal expansion portion 231 is located on the right side of the connector 232 along the X direction shown in the figure, and the included angle between them is acute. Alternatively, the thermal expansion portion 231 can be located on the left side of the connector 232 along the X direction shown in the figure, and the included angle between them is obtuse. Furthermore, to ensure good structural symmetry of the fiber Bragg grating temperature and pressure sensor, such as... Figure 4 As shown, both connectors 230 can be provided with thermally conductive expansion portions 231, and the two thermally conductive expansion portions 231 are arranged opposite to each other. In this case, the second grating 330 can be located on one of the two thermally conductive expansion portions 231.

[0094] See Figure 1 , Figure 6 and Figure 7 In some embodiments, the fiber optic temperature and pressure sensor further includes a first hinge member 400. A first insertion groove 211 is provided on the first support member 210, and a portion of the connecting part 232 is inserted into the first insertion groove 211. A sliding hole 2325 is provided on the connecting part 232. Two first insertion holes 212 communicating with the first insertion groove 211 are provided on the groove wall of the first insertion groove 211. The first hinge member 400 passes through one of the two first insertion holes 212, the sliding hole 2325 and the other of the two first insertion holes 212 in sequence, so that the connecting part 232 is hinged to the first support member 210.

[0095] This design allows for quick assembly or disassembly of the connecting part 232 and the first support member 210 without the need for complex tools, which helps reduce production and maintenance costs. By creating a slot on the first support member 210, a portion of the connecting part 232 is inserted into the first slot 211, and a precise hinge between the connecting part 232 and the first support member 210 is achieved through the first hinge member 400, thereby enhancing the structural strength between the connecting part 232 and the first support member 210.

[0096] By opening a sliding hole 2325 on the connecting part 232, the connecting part 232 can have a certain displacement range within the first insertion groove 211, ensuring that the connecting part 232 can adapt to the deformation degree of the sensor base 100 under different pressures. That is, the displacement range can adapt to the deformation under different pressures, which helps to ensure that the movement trajectory of the connecting part 232 matches the deformation of the sensor base 100, thereby improving the response speed and measurement accuracy of the sensor.

[0097] In a specific implementation, the first hinge member 400 can be configured as a pin, which includes a contact portion 410 and a hinge portion 420 arranged sequentially. Both the contact portion 410 and the hinge portion 420 are cylindrical. The diameter of the contact portion 410 is larger than the diameter of the hinge portion 420 and the diameter of the first insertion hole 212, and the diameter of the hinge portion 420 is smaller than the diameter of the first insertion hole 212. The hinge portion 420 passes through one of the two first insertion holes 212, the sliding hole 2325 and the other of the two first insertion holes 212 in sequence to achieve clearance fit, and the contact portion 410 contacts the first support member 210. In this way, the connector 230 and the first support member 210 are hinged.

[0098] See Figure 1 , Figure 4 and Figure 8 In some embodiments, the fiber optic temperature and pressure sensor further includes two second hinge members 500, each corresponding to a connecting portion 232. A second insertion groove 221 is provided on the second support member 220, and a portion of the connecting portion 232 is inserted into the second insertion groove 221. A connecting hole 2326 is provided on the connecting portion 232. Two second insertion holes 222 communicating with the second insertion groove 221 are provided on the groove wall of the second insertion groove 221. The second hinge member 500 passes through one of the two second insertion holes 222, the connecting hole 2326, and the other of the two second insertion holes 222 in sequence, so that the connecting portion 232 is hinged to the second support member 220.

[0099] This design allows for quick assembly or disassembly of the connecting part 232 and the second support member 220 without the need for complex tools, which helps reduce production and maintenance costs.

[0100] In a specific implementation, the second hinge member 500 can be set as a pin as in the aforementioned embodiment, wherein the diameter of the second insertion hole 222 is equal to the diameter of the connecting hole 2326, the diameter of the contact portion 410 of the pin is greater than the diameter of the hinge portion 420 of the pin and the diameter of the connecting hole 2326, and the diameter of the hinge portion 420 is smaller than the diameter of the connecting hole 2326; the hinge portion 420 passes through one of the two second insertion holes 222, the connecting hole 2326 and the other of the two second insertion holes 222 in sequence for clearance fit, and the contact portion 410 contacts the second support member 220, thus completing the hinge connection between the connector 230 and the second support member 220.

[0101] See Figure 9In some examples, the connecting portion 232 includes a first insertion segment 2321, a first support segment 2322, a second insertion segment 2323, and a second support segment 2324 connected in sequence; a connecting hole 2326 is located on the first insertion segment 2321, a sliding hole 2325 is located on the second insertion segment 2323, and a connecting surface 233 is provided on the second support segment 2324; the distance between the center of the connecting hole 2326 and the center of the sliding hole 2325 is less than the distance between the center of the sliding hole 2325 and the connecting surface 233.

[0102] With this configuration, the two connectors 230 can move in opposite directions, which can amplify the deformation of the sensor base 100 caused by the pressure, making the sensitivity and resolution of the pressure measurement more accurate.

[0103] Understandably, on the basis of ensuring that the distance between the center of the connecting hole 2326 and the center of the sliding hole 2325 is less than the distance between the center of the sliding hole 2325 and the connecting surface 233, the position and angle of each hinge point can be optimized and adjusted to further improve the conversion effect from mechanical displacement to the position change of the fiber optic grating 310, reduce signal distortion, and improve the response speed and measurement accuracy of the fiber optic grating temperature and pressure sensor.

[0104] In specific implementation, the thickness of the first insertion segment 2321 is less than the thickness of the first support segment 2322, and the thickness of the second insertion segment 2323 is less than the thickness of the first insertion segment 2321. In this way, the size of the first insertion slot 211 and the second insertion slot 221 can be optimized, making the structure of the first support member 210 and the second support member hinged to the connector 230 small and compact. At the same time, it can ensure that the connecting part 232 has good structural strength, avoiding affecting the connection stability between the connecting part 232 and the first support member 210 and the connection stability between the connecting part 232 and the second support member 220.

[0105] In a specific example, fiber 310 is a single-mode fiber with a polyimide coating.

[0106] Therefore, single-mode fiber has low loss and high bandwidth characteristics, which can support high-precision measurement of grating reflection wavelength, making the measurement of temperature and pressure by fiber optic grating temperature and pressure sensors more accurate.

[0107] The low attenuation characteristics of single-mode optical fiber help maintain good signal quality during long-distance transmission, making it suitable for deep well areas of oil and gas wells or remote monitoring applications. It eliminates the need for relay amplification, reducing the complexity and cost of detection.

[0108] By applying a polyimide coating to single-mode optical fibers, the polyimide coating exhibits excellent chemical stability and corrosion resistance. This protects the single-mode fiber from corrosion by acidic and alkaline fluids found in oil and gas wells, extending the lifespan of both the fiber and the sensor. During use, the polyimide coating enhances the adaptability of the single-mode fiber to environmental changes, enabling fiber Bragg grating temperature and pressure sensors to operate over a wider range of temperature and pressure conditions, thus expanding their application scope.

[0109] In addition, polyimide has good thermal stability and can maintain structural integrity in high-temperature environments, ensuring the stable performance of single-mode optical fibers in high-temperature oil and gas wells and avoiding measurement errors caused by temperature changes.

[0110] Furthermore, the coating provides additional mechanical strength to the single-mode fiber, protecting it from physical damage, reducing failures caused by accidental impacts or wear, and improving the durability and reliability of the fiber Bragg grating temperature and pressure sensor.

[0111] In practice, the first grating 320 and the second grating 330 set on the optical fiber 310 can be directly written on the optical fiber 310 without stripping the polyimide coating by a femtosecond laser. The femtosecond laser has extremely high pulse energy density and extremely short pulse width, which can achieve high-precision grating writing.

[0112] In some embodiments, the grating region length of the first grating 320 is 1mm-5mm, and the grating region length of the second grating 330 is equal to the grating region length of the first grating 320; the difference between the center wavelength of the first grating 320 and the center wavelength of the second grating 330 is ≥3nm.

[0113] Specifically, the choice of grating length affects the resolution and signal-to-noise ratio of the grating; a longer grating length can provide higher measurement accuracy.

[0114] For example, the grating area length of the first grating 320 is 1mm-5mm. For instance, the grating area length of the first grating 320 can be set to 1mm. In this way, while ensuring the resolution of the first grating 320, good signal quality and strong reflection intensity are also maintained, thereby improving the accuracy of pressure measurement.

[0115] The grating length is related to the sensor's sensitivity and bandwidth; an appropriate length can balance these two factors. Choosing a grating length within the range of 1mm-5mm ensures high sensitivity to temperature and pressure changes while avoiding excessively narrow bandwidth limitations, enabling the sensor to cope with rapidly changing environments.

[0116] Setting the gate length in the range of 1mm-5mm helps ensure the economy and feasibility of manufacturing, avoiding increased costs or decreased performance caused by gates that are too long or too short.

[0117] By setting the difference in center wavelength between the first grating 320 and the second grating 330, independent demodulation of temperature and pressure signals is ensured, thereby improving the accuracy and reliability of the measurement.

[0118] In practice, the difference between the center wavelengths of the two sensors is at least 3 nm. This avoids cross-interference between the reflected signals during demodulation, helps maintain the stability of temperature and pressure measurements, reduces mutual influence, and ensures the reliability of long-term measurements. At the same time, it simplifies the signal demodulation algorithm, reduces the difficulty of data processing, and improves the practicality and response speed of the sensor.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A fiber Bragg grating temperature and pressure sensor, characterized in that, It includes a sensor base (100), a support assembly (200), and a detection assembly (300); The sensor base (100) is used to connect to the pressure testing port of the oil and gas well. The sensor base (100) is provided with a pressure inlet groove (110). The support assembly (200) includes a first support member (210), two second support members (220) and two connecting members (230). The first support member (210) and the two second support members (220) are all disposed on the sensor base (100). The first support member (210) is located between the two second support members (220). The connecting members (230) and the second support members (220) are hinged one-to-one, and both connecting members (230) are hinged to the first support member (210). The detection component (300) includes an optical fiber (310) and a first grating (320) and a second grating (330) disposed on the optical fiber (310). Both connectors (230) are connected to the optical fiber (310). The first grating (320) is located between the two connectors (230). One of the two connectors (230) is provided with a thermally conductive expansion portion (231). The second grating (330) is located on the thermally conductive expansion portion (231). The sensor base (100) is configured to deform when pressed in the pressure groove (110); the two second supports (220) are used to move relative to the first support (210) when the sensor base (100) deforms, so as to drive the corresponding connector (230) to rotate toward the sensor base (100) and cause the two connectors (230) to move in opposite directions.

2. The fiber Bragg grating temperature and pressure sensor according to claim 1, characterized in that, The sensor base (100) is cylindrical. The axis of the first support member (210) coincides with the axis of the sensor base (100). Two second support members (220) are symmetrically arranged on opposite sides of the first support member (210). The second support members (220) correspond one-to-one with the pressure groove (110).

3. The fiber optic grating temperature and pressure sensor according to claim 2, characterized in that, The distance between the wall of the pressure inlet groove (110) and the side wall of the adjacent sensor base (100) is greater than or equal to the distance between the bottom of the pressure inlet groove (110) and the distance between the side of the sensor base (100) away from the opening of the pressure inlet groove (110); The distance between the bottom of the pressure inlet groove (110) and the side of the sensor base (100) away from the opening of the pressure inlet groove (110) is 1mm-3mm.

4. The fiber Bragg grating temperature and pressure sensor according to any one of claims 1 to 3, characterized in that, The length of the second support member (220) along the axis of the sensor base (100) is less than the length of the first support member (210) along the axis of the sensor base (100).

5. The fiber optic grating temperature and pressure sensor according to claim 4, characterized in that, The connector (230) includes a connecting part (232), which is sequentially hinged to the end of the second support member (220) away from the sensor base (100) and the end of the first support member (210) away from the sensor base (100). The connecting part (232) has a connecting surface (233), the optical fiber (310) is connected to the connecting surface (233), the thermal conductivity expansion part (231) is connected to the connecting part (232), and the side of the thermal conductivity expansion part (231) away from the sensor base (100) is flush with the connecting surface (233).

6. The fiber optic grating temperature and pressure sensor according to claim 5, characterized in that, It also includes a first hinge (400), on which a first insertion groove (211) is provided, and part of the connecting part (232) is inserted into the first insertion groove (211); The connecting part (232) is provided with a sliding hole (2325), and the groove wall of the first insertion groove (211) is provided with two first insertion holes (212) that communicate with the first insertion groove (211). The first hinge member (400) passes through one of the two first insertion holes (212), the sliding hole (2325) and the other of the two first insertion holes (212) in sequence, so that the connecting part (232) is hinged to the first support member (210).

7. The fiber Bragg grating temperature and pressure sensor according to claim 6, characterized in that, It also includes two second hinge members (500), which correspond one-to-one with the connecting part (232). The second support member (220) has a second insertion groove (221), and part of the connecting part (232) is inserted into the second insertion groove (221). The connecting part (232) is provided with a connecting hole (2326), and the groove wall of the second insertion groove (221) is provided with two second insertion holes (222) that communicate with the second insertion groove (221). The second hinge member (500) passes through one of the two second insertion holes (222), the connecting hole (2326), and the other of the two second insertion holes (222) in sequence, so that the connecting part (232) is hinged to the second support member (220).

8. The fiber optic temperature and pressure sensor according to claim 7, characterized in that, The connecting part (232) includes a first plug-in section (2321), a first support section (2322), a second plug-in section (2323), and a second support section (2324) connected in sequence; the connecting hole (2326) is located on the first plug-in section (2321), the sliding hole (2325) is located on the second plug-in section (2323), and the second support section (2324) has the connecting surface (233); The distance between the center of the connecting hole (2326) and the center of the sliding hole (2325) is less than the distance between the center of the sliding hole (2325) and the connecting surface (233).

9. The fiber Bragg grating temperature and pressure sensor according to any one of claims 1 to 3, characterized in that, The optical fiber (310) is a single-mode optical fiber, and the single-mode optical fiber has a polyimide coating layer.

10. The fiber optic temperature and pressure sensor according to any one of claims 1 to 3, characterized in that, The grating region length of the first grating (320) is 1mm-5mm, and the grating region length of the second grating (330) is equal to the grating region length of the first grating (320); The difference between the center wavelength of the first grating (320) and the center wavelength of the second grating (330) is ≥3nm.

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