Wellhead multi-parameter sensor based on optical fiber sensing technology

Abstract

The invention relates to a wellhead multi-parameter sensor based on an optical fiber sensing technology, which comprises a framework, a protective shell, an optical fiber temperature and pressure integrated sensor, a pressure-resistant shell, an optical fiber load sensor, a pressure guide piece and a sensor tail cable, and is characterized in that the optical fiber temperature and pressure integrated sensor and the optical fiber load sensor are integrated in a cavity assembled by the framework and the protective shell; the optical fiber temperature and pressure integrated sensor is connected with the oil pipe through the pressure guide piece and used for monitoring the temperature and pressure in the oil pipe in real time. The optical fiber load sensor is fixed to the outer wall of the framework and used for monitoring the strain of the framework and reversely deducing the oil pipe load borne by the framework. Data such as wellhead temperature, pressure and oil pipe load of an oil well can be collected in real time, and accurate data analysis is provided through field application of a standardized data collection integrated system.

Description

Technical field:

[0001] The invention belongs to the technical field of optical fiber sensing and relates to a wellhead multi-parameter sensor based on the optical fiber sensing technology. Background technology:

[0002] Real-time monitoring of wellhead temperature, pressure, and tubing load is of great significance for ensuring efficient and safe production and exploitation in oil fields. The collected wellhead data provides a scientific basis for analyzing the life and output of oil wells. Since oil well exploitation is generally carried out in remote and relatively harsh places, the traditional manual on-site well inspection and data recording and analysis of pumping well working conditions are not only inefficient but also very expensive. With the rapid development of modern network technology, sensor technology, and microprocessor technology, and in view of the rapid increase in the number of oil wells in current oil fields, the construction of digital oil fields is urgently needed. At present, there is no technical record of wellhead multi-parameter sensors based on fiber optic sensing technology. Summary of the invention:

[0003] The technical problem to be solved by the present invention is to provide a wellhead multi-parameter sensor based on optical fiber sensing technology, which can collect data such as wellhead temperature, pressure and oil pipe load in real time, and provide accurate data analysis through the application of standardized data acquisition integration system on site, and provide reasonable decision-making suggestions for management departments and decision-makers, thereby improving the level of production information management and application.

[0004] The technical solution of the present invention is to provide a wellhead multi-parameter sensor based on optical fiber sensing technology, including a skeleton, a protective shell, an optical fiber temperature and pressure integrated sensor, a pressure-resistant shell, an optical fiber load sensor, a pressure guide and a sensor tail cable. The optical fiber temperature and pressure integrated sensor and the optical fiber load sensor are integrated in a cavity assembled by the skeleton and the protective shell. The optical fiber temperature and pressure integrated sensor is connected to the oil pipe through the pressure guide to monitor the temperature and pressure in the oil pipe in real time; the optical fiber load sensor is fixed to the outer wall of the skeleton to monitor the strain of the skeleton and infer the oil pipe load on the skeleton; the tail fibers of the optical fiber temperature and pressure integrated sensor and the optical fiber load sensor are fused with the optical fiber of the sensor tail cable.

[0005] Preferably, when the protective shell is assembled with the frame, one end is sealed by a radial sealing structure, and the other end is sealed by a radial sealing structure or laser welding.

[0006] Preferably, the optical fiber temperature and pressure integrated sensor is a single-end fiber-outlet structure, and the optical fiber temperature and pressure integrated sensor is a fiber grating sensor or an optical fiber FP sensor.

[0007] Preferably, the optical fiber integrated temperature and pressure sensor is sealed at one end in a pressure-resistant housing, and the two are sealed by a radial sealing structure, and the pressure at the seal is not lower than the maximum pressure in the oil pipe when the oil well is working normally.

[0008] Preferably, the optical fiber integrated temperature and pressure sensor is fixed to the frame through a pressure guide piece, and a pressure inlet hole is provided at the assembly point of the frame and the pressure guide piece, and the pressure inlet hole is used to transfer the pressure in the oil pipe to the optical fiber integrated temperature and pressure sensor.

[0009] Preferably, the optical fiber load sensor is fixed to the outer wall of the frame, the optical fiber load sensor is a patch-type optical fiber Bragg grating strain sensor or a bare optical fiber Bragg grating, and the optical fiber load sensor has its own temperature compensation.

[0010] Preferably, a transition piece is also included, and the sensor tail cable and the transition piece are sealed and protected against bending by cold vulcanization, and the transition piece is assembled with the frame by two radial sealing structures.

[0011] Preferably, threaded interfaces matching the oil well tubing are reserved at both ends of the skeleton to facilitate direct tightening and installation with the oil well tubing.

[0012] Preferably, the protective shell can withstand the maximum pressure outside the oil pipe when the oil well is working normally; the frame and the protective shell are made of metal material 2CR13.

[0013] Furthermore, the optical fiber temperature and pressure integrated sensor, the pressure-resistant housing and the pressure-conducting parts are all made of precipitation-hardened nickel-chromium-iron alloy Inconel 718.

[0014] Furthermore, the reserved length of the sensor tail cable is not less than 5m, and its mechanical properties meet the requirements of "GJB142B-2009 General Specification for Optical Cables".

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) The sensor end only emits laser light through the demodulation processor, which does not require power supply and is inherently safe, making it very suitable for use in flammable and explosive places such as oil wells.

[0017] (2) The sensor ends are all sensed and transmitted by optical fiber, which is immune to electromagnetic interference and lightning protection. The material of the optical fiber is silicon dioxide, which has stable performance, high and low temperature resistance, acid and alkali resistance, and strong environmental adaptability;

[0018] (3) The demodulation processor can demodulate and analyze the sensor signal in real time to achieve online monitoring. The data sampling rate can reach hundreds of Hz and the response is fast. Description of the drawings:

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 It is a schematic diagram of the internal structure of the present invention.

[0021] Figure 3 It is a schematic diagram of the skeleton structure of the present invention.

[0022] Figure 4 It is a schematic diagram of the structure of the optical fiber temperature and pressure integrated sensor of the present invention.

[0023] Figure 5 It is a schematic diagram of the sensor pigtail processing of the present invention.

[0024] Figure 6 : is the relationship curve between the wavelength value and pressure of the optical fiber temperature and pressure integrated sensor in this embodiment.

[0025] Figure 7 : is the relationship curve between the output value and pressure of the optical fiber load sensor in this embodiment.

[0026] Figure 8 : is the relationship curve between the wavelength value and the load of the optical fiber load sensor in this embodiment.

[0027] Fig. 9 : is the relationship curve between the output value and load of the optical fiber temperature and pressure integrated sensor in this embodiment. Specific implementation method:

[0028] The present invention will be further described below with reference to the accompanying drawings:

[0029] The present invention discloses a wellhead multi-parameter sensor based on optical fiber sensing technology, such as Figure 1 As shown, it includes a skeleton 1, a protective shell 2, an optical fiber temperature and pressure integrated sensor 3, a pressure-resistant shell 4, an optical fiber load sensor 5, a pressure-conducting component 6, an adapter 7, and a sensor tail cable 8.

[0030] In this embodiment, the skeleton 1 and the protective shell 2 are large in size. In order to save costs, the metal material 2CR13 commonly used in the oil well industry is selected for processing. The protective shell needs to be able to withstand the maximum pressure outside the oil pipe when the oil well is working normally. The optical fiber temperature and pressure integrated sensor 3, the pressure-resistant shell 4 and the pressure guide 6 are in direct contact with crude oil and are always in a high-temperature, high-pressure and highly corrosive environment. In addition, they are small in size, so the precipitation-hardened nickel-chromium-iron alloy Inconel 718 with high strength, good toughness and corrosion resistance in both high and low temperature environments is selected for processing.

[0031] The fiber optic temperature and pressure integrated sensor 3 in this embodiment uses the fiber optic Bragg grating sensor principle and a side-pressured structure to convert the ambient pressure into the wavelength drift of the pressure measuring grating, and infer the change of the ambient pressure by monitoring the drift, such as Figure 4As shown. The sensor has a built-in temperature compensation grating in a free state at one end, which can not only compensate the temperature of the pressure measurement grating, but also measure the ambient temperature. The optical fiber temperature and pressure integrated sensor 3 has a single-end fiber outlet, and the fiber outlet end is designed to be assembled with two radial seals, through which it is assembled and sealed with the pressure-resistant housing 4, as shown in FIG. Figure 2 The pressure-resistant shell 4 is assembled with the pressure-conducting member 6 through two radial sealing structures to form a closed air cavity, and the pressure-conducting member 6 is assembled and fixed to the surface of the frame 1 through two axial and radial sealing structures. Figure 3 A pressure inlet hole 9 is provided at the assembly position of the frame 1 and the pressure guiding member 6 , and the pressure inlet hole 9 is used to transmit the pressure in the oil pipe to the optical fiber temperature and pressure integrated sensor 3 .

[0032] The optical fiber load sensor 5 in this embodiment is based on the principle of measuring strain with a bare optical fiber Bragg grating. The grating area of ​​the load grating is sealed with 353ND glue and pasted to the outer wall of the skeleton 1. The stretching or contraction of the oil pipe caused by the load change is converted into the wavelength drift of the grating, and the load change is inferred by monitoring its drift. The temperature compensation grating cascaded with the load grating is in a free state, which is used to perform temperature compensation on the load grating.

[0033] like Figure 5 As shown, after the pigtails of the optical fiber temperature and pressure integrated sensor 3 and the optical fiber load sensor 5 in this embodiment are fused with the optical fiber of the sensor tail cable 8, the remaining loose fibers are fixed to the outer wall of the skeleton 1 in an orderly manner and fixed along the entire line with silicone glue to prevent them from loosening.

[0034] The sensor of the present invention is further provided with an adapter 7. The sensor tail cable 8 and the adapter 7 are sealed and protected against bending by cold vulcanization. The adapter 7 is assembled with the frame 1 by two radial sealing structures.

[0035] In addition, in order to facilitate direct tightening and installation with the oil well pipe, threaded interfaces matching the oil well pipe are reserved at both ends of the skeleton 1.

[0036] At the same time, the reserved length of the sensor tail cable 8 is not less than 5m, and its mechanical properties meet the requirements of "GJB142B-2009 General Specification for Optical Cables".

[0037] In order to verify the beneficial effects of the present invention, the sensor of this embodiment is subjected to pressure, load and other related tests. In the pressure test, the pressure test range is 0-50MPa, with an interval of 10MPa. Figure 6 and Figure 7They are the output results of the fiber optic temperature and pressure sensor 3 and the fiber optic load sensor 5 in this embodiment. Among them, the wavelength of the fiber optic temperature and pressure sensor 3 has a good linear relationship with the pressure, and its pressure sensitivity is 0.0236nm / MPa, and the linearity is 99.99%, which lays the foundation for high-precision pressure measurement; the output value of the fiber optic load sensor 5 does not show an upward or downward trend under the action of pressure, indicating that its output value is not affected by the environmental pressure. In the load test, the load test range is 0~500KN, with an interval of 100KN, Figure 8 and Fig. 9 They are the output results of the optical fiber temperature and pressure integrated sensor 3 and the optical fiber load sensor 5 in this embodiment. Among them, the wavelength of the optical fiber load sensor 5 has a good linear relationship with the load, its pressure sensitivity is 0.0031nm / KN, and its linearity is 99.96%, which lays the foundation for high-precision load measurement; the output value of the optical fiber temperature and pressure integrated sensor 3 does not show an upward or downward trend under the load, indicating that its output value is not affected by the environmental load.

[0038] The above is only an explanation of the preferred embodiments of the present invention, which should not be construed as a limitation on the claims. Any equivalent process changes made using the present invention specification are included in the patent protection scope of the present invention.

Claims

1. A wellhead multi-parameter sensor based on optical fiber sensing technology, characterized in that: It includes a skeleton, a protective shell, an optical fiber temperature and pressure integrated sensor, a pressure-resistant shell, an optical fiber load sensor, a pressure-conducting part and a sensor tail cable. The optical fiber temperature and pressure integrated sensor and the optical fiber load sensor are integrated in a cavity assembled by the skeleton and the protective shell. The optical fiber temperature and pressure integrated sensor is connected to the oil pipe through the pressure-conducting part to monitor the temperature and pressure in the oil pipe in real time; the optical fiber load sensor is fixed to the outer wall of the skeleton to monitor the strain of the skeleton and infer the oil pipe load on the skeleton; the tail fibers of the optical fiber temperature and pressure integrated sensor and the optical fiber load sensor are fused with the optical fiber of the sensor tail cable.

2. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1, characterized in that: When the protective shell and the frame are assembled, one end is sealed by a radial sealing structure, and the other end is sealed by a radial sealing structure or laser welding.

3. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1 is characterized in that: The optical fiber temperature and pressure integrated sensor is a single-end fiber-outlet structure, and the optical fiber temperature and pressure integrated sensor is a fiber grating sensor or an optical fiber FP sensor.

4. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 3 is characterized in that: The optical fiber temperature and pressure integrated sensor is sealed at one end in the pressure-resistant housing, and the two are sealed by a radial sealing structure. The pressure at the sealing point is not lower than the maximum pressure in the oil pipe when the oil well is working normally.

5. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1 is characterized in that: The optical fiber temperature and pressure integrated sensor is fixed on the frame through a pressure guide piece. A pressure inlet hole is provided at the assembly point of the frame and the pressure guide piece. The pressure inlet hole is used to transmit the pressure in the oil pipe to the optical fiber temperature and pressure integrated sensor.

6. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1 is characterized in that: The optical fiber load sensor is fixed on the outer wall of the frame. The optical fiber load sensor is a patch type optical fiber Bragg grating strain sensor or a bare optical fiber Bragg grating. The optical fiber load sensor has its own temperature compensation.

7. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1 is characterized in that: It also includes an adapter. The sensor tail cable and the adapter are sealed and protected against bending by cold vulcanization. The adapter is assembled with the frame by two radial sealing structures.

8. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1, characterized in that: Threaded interfaces matching the oil well pipes are reserved at both ends of the frame, so as to facilitate direct tightening and installation with the oil well pipes.

9. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1, characterized in that: The protective shell can withstand the maximum pressure outside the oil pipe when the oil well is working normally; the frame and the protective shell are made of metal material 2CR13.

10. The wellhead multi-parameter sensor based on optical fiber sensing technology according to claim 1, characterized in that: The optical fiber temperature and pressure integrated sensor, pressure-resistant housing and pressure-conducting parts are all made of precipitation-hardened nickel-chromium-iron alloy Inconel 718.

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