A Method and System for Detecting Water Content in Crude Oil Based on Spiral Optical Fiber Probes

Abstract

The present invention discloses a method and a system for detecting the water content of crude oil based on a spiral optical fiber probe; the method includes: placing crude oil in a container; one or more spiral optical fiber probes made of single-mode optical fiber are dispersedly placed in the container; the probes are perpendicular to the bottom surface of the container and in contact with the bottom surface; the height of the probes is not less than the height of the container; the inner wall of the container and the surface of the spiral optical fiber probes are both sprayed with superhydrophobic and superoleophobic materials to promote the upper and lower separation of oil and water in the crude oil; after realizing the upper and lower separation of oil and water, input light waves into the spiral optical fiber probe by using a laser light source; use a spectrometer to detect the light waves reflected or transmitted from the spiral optical fiber probe to obtain detection spectral data; determine the current liquid level height and the height of the oil-water interface in the container based on the detection spectral data; calculate the water content of the crude oil based on the liquid level height and the height of the oil-water interface. The present invention can improve the detection efficiency of the water content of crude oil.

Description

Technical Field

[0001] The present invention belongs to the field of crude oil water content detection, and particularly relates to a method and system for detecting the water content of crude oil based on a spiral optical fiber probe. Background Art

[0002] The water content of crude oil directly affects the work of crude oil extraction, dehydration, sales, refining, etc. During the exploration and exploitation of oil fields, as well as during the transportation and storage of crude oil, it is required to detect the water content of crude oil. The water content of crude oil is of extremely important significance for determining the water outlet position of oil wells, the oil-producing layer position, estimating the size of oil fields in advance, the crude oil production, and predicting the development life of oil wells, etc. Therefore, timely and accurately detecting the water content of crude oil can reflect the working state of oil wells, help relevant departments reduce energy consumption, lower costs, and quickly respond to problems to avoid the occurrence of safety accidents, and achieve automated management of oil fields.

[0003] In the prior art, for the method of detecting the water content of crude oil based on optical fibers, generally, the spectral analysis method of oil-water mixture is adopted. This method realizes the extraction of spectral features through dimensionality reduction techniques such as principal component analysis and successive projection algorithm, and then determines the water content of crude oil according to the extracted features.

[0004] However, for the above method, when performing a detection of the water content of crude oil once, dozens of spectral data need to be extracted, and both the principal component analysis and successive projection algorithm used are relatively complex. Therefore, the detection efficiency of the existing crude oil water content detection is relatively low. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method and system for detecting the water content of crude oil based on a spiral optical fiber probe.

[0006] The technical problems to be solved by the present invention are realized through the following technical solutions:

[0007] A method for detecting the water content of crude oil based on a spiral optical fiber probe includes:

[0008] Placing the crude oil to be detected for water content into a container; one or more spiral optical fiber probes made of single-mode optical fibers are dispersedly placed in the container; the spiral optical fiber probes are perpendicular to the bottom surface of the container and in contact with the bottom surface; the height of the spiral optical fiber probes is not lower than the height of the container; the inner wall of the container and the surface of the spiral optical fiber probes are both sprayed with superhydrophobic and superoleophobic materials to promote the upper and lower separation of oil and water in the crude oil;

[0009] After realizing the upper and lower separation of oil and water, input light waves into the spiral optical fiber probes by using a laser light source;

[0010] The light waves reflected or transmitted from the spiral optical fiber probe are detected by a spectrometer to obtain detected spectral data;

[0011] Based on the detected spectral data, the current liquid level height and the height of the oil-water interface in the container are determined;

[0012] Based on the liquid level height and the height of the oil-water interface, the water cut of the crude oil is calculated.

[0013] Preferably, the calculating the water cut of the crude oil based on the liquid level height and the height of the oil-water interface includes:

[0014] The total volume of the crude oil is determined by using the liquid level height;

[0015] The volume of water in the crude oil is determined by using the height of the oil-water interface, and the total volume is subtracted by the volume of water to obtain the volume of pure petroleum in the crude oil;

[0016] The water cut of the crude oil is calculated by using the volume of water, the volume of pure petroleum, the density of water and the density of pure petroleum.

[0017] Preferably, the method further includes the step of detecting the ambient temperature;

[0018] The calculating the water cut of the crude oil by using the volume of water, the volume of pure petroleum, the density of water and the density of pure petroleum includes:

[0019] The water cut of the crude oil is calculated by using the volume of water, the volume of pure petroleum, the density of water corresponding to the ambient temperature and the density of pure petroleum.

[0020] Preferably, the superhydrophobic and superoleophobic material includes: Teflon, nano-zinc oxide or calcium alginate.

[0021] Preferably, the determining the current liquid level height and the height of the oil-water interface in the container based on the detected spectral data includes:

[0022] From a plurality of experimental spectral data obtained by pre-calibration tests, a target spectral data closest to the detected spectral data is found;

[0023] The liquid level height and the height of the oil-water interface corresponding to the setting when the target spectral data is measured are determined as the current liquid level height and the height of the oil-water interface in the container.

[0024] Preferably, the spiral optical fiber probe satisfies the following conditions:

[0025] The attenuation coefficient of the spiral optical fiber probe in air is less than a preset upper limit, and the difference between the attenuation coefficient in air and the attenuation coefficient in liquid is greater than a preset lower limit;

[0026] Among them, the upper limit is determined according to the detection sensitivity of the spectrometer, and the lower limit is determined according to the detection accuracy of the spectrometer.

[0027] Preferably, the spiral optical fiber probe also satisfies the following conditions:

[0028] The ratio of the axial radius to the pitch of the spiral optical fiber probe does not exceed 1.

[0029] Preferably, there are multiple laser light sources; the spectrometer includes multiple detection channels;

[0030] The number of the laser light sources and the number of the detection channels both match the number of the spiral optical fiber probes.

[0031] The present invention also provides a crude oil water content detection system based on a spiral optical fiber probe, including:

[0032] A container for holding crude oil; one or more segments of spiral optical fiber probes made of single-mode optical fibers are dispersedly placed in the container; the spiral optical fiber probes are perpendicular to the bottom surface of the container and in contact with the bottom surface; the height of the spiral optical fiber probes is not lower than the height of the container; the inner wall of the container and the surface of the spiral optical fiber probes are both sprayed with superhydrophobic and superoleophobic materials to promote the upper and lower separation of oil and water in the crude oil;

[0033] A laser light source; the laser light source is used to input light waves into the spiral optical fiber probes after the upper and lower separation of oil and water is achieved.

[0034] A spectrometer; the spectrometer is used to detect the light waves reflected or transmitted from the spiral optical fiber probes to obtain detection spectral data.

[0035] A data processing module; the data processing module is used to determine the current liquid level height and the height of the oil-water interface in the container based on the detection spectral data, and is also used to calculate the water content of the crude oil based on the liquid level height and the height of the oil-water interface.

[0036] Preferably, there are multiple containers in which the spiral optical fiber probes are placed.

[0037] In the crude oil water content detection method based on a spiral optical fiber probe provided by the present invention, a superhydrophobic and superoleophobic material is sprayed on the inner wall of the container for holding crude oil. Utilizing the characteristics that pure petroleum and water have different densities and are completely immiscible, when the crude oil is placed in the container, the oil and water can naturally separate with the oil on top and the water at the bottom. One or more spiral optical fiber probes made of single-mode optical fiber are dispersedly placed in the container; the surface of the spiral optical fiber probe is also sprayed with a superhydrophobic and superoleophobic material, which will not cause liquid to stick to the wall and is also conducive to the up-and-down separation of oil and water. Since the effective refractive index of a single-mode optical fiber depends on the refractive index of the surrounding medium, when the spiral optical fiber probe is immersed in the liquid with separated oil and water, the refractive index of the segment located in water is shifted to a certain extent under the influence of water, and the refractive index of the segment located in pure petroleum is shifted to different extents under the influence of pure petroleum. At this time, these two segments can be regarded as two independent gratings of the spiral optical fiber probe. The refractive index of the entire spiral optical fiber probe depends on the length ratio of these two gratings. When the crude oil has different water-oil ratios, the length ratios of these two gratings are different. Therefore, based on the detection spectral data of the light wave reflected or transmitted from the spiral optical fiber probe, the liquid level height and the height of the oil-water interface in the container can be determined. Correspondingly, knowing the liquid level height and the height of the oil-water interface, it is easy to calculate the volumes of pure petroleum and water, and thus calculate the water content of the crude oil.

[0038] In summary, compared with the prior art, the detection method of the present invention only needs to extract one spectral data for one detection of the water content of crude oil, which takes less time; moreover, the calculation method of the present invention for calculating the water content of crude oil based on the liquid level height and the height of the oil-water interface is relatively simple, so the detection speed is faster. On the basis of the fast detection speed, the present invention can continuously perform detections, so as to achieve the effect of real-time monitoring of the water content of crude oil in the container.

[0039] In addition, when the volume of the container is large, the present invention can arrange multiple spiral optical fiber probes in the container, and these probes can perform detections respectively; by comparing the detection results of each probe, a more accurate and reliable water content of crude oil can be obtained.

[0040] The following will further describe the present invention in detail with reference to the drawings. Description of the Drawings

[0041] Figure 1 is a schematic flow chart of a crude oil water content detection method based on a spiral optical fiber probe provided by an embodiment of the present invention;

[0042] Figure 2 is Figure 1 a schematic structural diagram of the container used in the method shown;

[0043] Figure 3It is a schematic structural diagram of an oil - water content detection system for crude oil based on a spiral optical fiber probe provided by an embodiment of the present invention;

[0044] Figure 4 It is a schematic structural diagram of another oil - water content detection system for crude oil based on a spiral optical fiber probe provided by an embodiment of the present invention. Specific embodiments

[0045] The following further describes the present invention in detail with reference to specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0046] In order to improve the detection efficiency of the water content in crude oil, an embodiment of the present invention provides an oil - water content detection method for crude oil based on a spiral optical fiber probe.

[0047] In the description of this specification, "crude oil" refers to the original petroleum containing water components, and "pure petroleum" is relative to "crude oil" and refers to petroleum without water.

[0048] See Figure 1 As shown, the oil - water content detection method for crude oil based on a spiral optical fiber probe provided by an embodiment of the present invention includes:

[0049] S10: Place the crude oil whose water content is to be detected into a container; one or more spiral optical fiber probes made of single - mode optical fibers are dispersedly placed in the container.

[0050] Among them, see Figure 2 As shown, the spiral optical fiber probe is perpendicular to the bottom surface of the container and in contact with the bottom surface; the height of the spiral optical fiber probe is not lower than the height of the container; the inner wall of the container and the surface of the spiral optical fiber probe are both sprayed with a super - hydrophobic and super - oleophobic material to promote the upper - lower separation of oil and water in the crude oil.

[0051] Water and pure petroleum have different densities and are completely immiscible. Therefore, when the crude oil is placed into the container, due to the existence of the super - hydrophobic and super - oleophobic material on the inner wall of the container and the surface of the spiral optical fiber probe, pure petroleum and water will not adhere to the wall, so that the natural separation of pure petroleum and water can be quickly achieved in the container, with pure petroleum on the upper layer and water on the lower layer. In addition, due to the existence of the super - hydrophobic and super - oleophobic material, the amount of liquid adhering to the surface of the spiral optical fiber probe can also be reduced, thereby reducing the influence of liquid adhesion on the measurement accuracy.

[0052] Among them, the super - hydrophobic and super - oleophobic material can include: Teflon, nano - zinc oxide or calcium alginate hydrogel. Specifically, a Teflon coating can be made on the inner wall of the container with Teflon; or many nano - zinc oxide microspheres can be made on the inner wall of the container with nano - zinc oxide; or a calcium alginate hydrogel can be made on the inner wall of the container with calcium alginate.

[0053] S20: After achieving the upper and lower separation of oil and water, a light wave is input into the spiral fiber optic probe using a laser light source.

[0054] Specifically, as Figure 3 shown, the laser light source can directly input a light wave into one end of the spiral fiber optic probe. Or, the laser light source can also, as Figure 4 shown, input a light wave into the spiral fiber optic probe through an optical circulator.

[0055] S30: Use a spectrometer to detect the light wave reflected or transmitted from the spiral fiber optic probe to obtain detection spectral data.

[0056] Specifically, if the light wave is input into the spiral fiber optic probe in the manner as Figure 3 shown, then the light wave transmitted from the spiral fiber optic probe can be received and detected by the spectrometer from the other end of the spiral fiber optic probe as Figure 3 shown. And if the light wave is input into the spiral fiber optic probe in the manner as Figure 4 shown, then the light wave reflected from the spiral fiber optic probe can be received and detected by the spectrometer from the feedback port of the optical circulator as Figure 4 shown.

[0057] As is well known to those skilled in the art, spectral data is the curve data that can form a spectrogram. The abscissa of this curve is the wavelength of light, and the ordinate is the power of light.

[0058] It can be understood that since the height of the spiral fiber is not lower than the height of the container, liquids at any height in the container can come into contact with the spiral fiber optic probe. Therefore, liquids at any height in the container can affect the refractive index of the spiral fiber optic probe; that is to say, the signal characteristics of the light wave finally output by the spiral fiber optic probe are generated under the combined action of pure oil and water in the container. And when the ratio of pure oil and water in the crude oil is different, the generated signal characteristics are also different. This specific difference is reflected in the intensity of the light wave finally output by the spiral fiber optic probe, that is, for the spectral data of the light wave finally output by the spiral fiber optic probe, the amplitude corresponding to the ordinate is different.

[0059] S40: Determine the current liquid level height and the height of the oil-water interface in the container based on the detection spectral data.

[0060] Specifically, this step S40 may include the following multiple sub-steps:

[0061] (1) Find a target spectral data that is closest to the detection spectral data from multiple experimental spectral data obtained from pre-calibration tests;

[0062] (2) Determine the liquid level height and the height of the oil-water interface set corresponding to the measured target spectral data, and use them as the current liquid level height L and the height of the oil-water interface h in the container.

[0063] Among them, there are multiple specific implementation methods for finding the target spectral data from multiple experimental spectral data. Exemplarily, in one implementation method, the amplitude mean value of each experimental spectral data can be calculated respectively, and the amplitude mean value of the detection spectral data can be calculated; then, take the experimental spectral data with the smallest difference from the amplitude mean value of the detection spectral data as the target spectral data. In another implementation method, each experimental spectral data can be subtracted from the target spectral data to obtain a difference curve; among them, when subtracting, the abscissas correspond one by one, and the amplitudes corresponding to the ordinates are subtracted; thus, take the experimental spectral data that can subtract a difference curve that fits the most closely to the X-axis (the straight line with the ordinate of 0) as the target spectral data.

[0064] In addition, when performing the calibration test in advance, in addition to considering different water-oil ratios, it is also possible to consider whether the density of the pure petroleum contained in the crude oil of different measurement batches in the actual measurement scenario is constant. If the density of the pure petroleum contained in the crude oil of different batches in the measurement scenario is not constant, then when performing the calibration test, various water-oil ratio experiments can be carried out separately for pure petroleum with different densities. In this way, when actually performing the test and searching for the target spectral data, only use a set of experimental spectral data corresponding to pure petroleum with the same density, which can make the measurement results more accurate.

[0065] S50: Calculate the water content of the crude oil based on the liquid level height and the height of the oil-water interface.

[0066] Specifically, this step S50 may include the following multiple sub-steps:

[0067] (1) Determine the total volume of the crude oil using the liquid level height L;

[0068] (2) Determine the volume of water in the crude oil using the height of the oil-water interface h, and subtract this volume of water from the total volume to obtain the volume of pure petroleum in the crude oil;

[0069] (3) Calculate the water content of the crude oil using the volume of water, the volume of pure petroleum, the density of water, and the density of pure petroleum.

[0070] It can be understood that the shape of the container is known. For example, in Figure 2The cylindrical container shown in []. Therefore, given the liquid level height L in the container, the total volume of the liquid in the container, i.e., the total volume of the crude oil, can be obtained through geometric derivation. Correspondingly, given the height h of the oil-water interface, the volume of water in the crude oil can be obtained through geometric derivation. Then, by subtracting the volume of water from the total volume, the volume of pure oil in the crude oil can be obtained.

[0071] Among them, the formula for calculating the water cut of crude oil using the volume of water, the volume of pure oil, the density of water, and the density of pure oil is as follows:

[0072]

[0073] Among them, ρ w represents the density of water, V w represents the volume of water, ρ o represents the density of pure oil, V o represents the volume of pure oil, and η represents the water cut of crude oil.

[0074] In one embodiment, if the ambient temperature where the container is located is not always at room temperature, the method for detecting the water cut of crude oil based on a spiral optical fiber probe provided by the embodiment of the present invention may further include the step of detecting the ambient temperature; correspondingly, when calculating the water cut of crude oil using the above formula, the above density of water and density of pure oil can be converted into the corresponding values at this ambient temperature.

[0075] In addition, there may be slight differences in the density of pure oil from different origins and of different qualities. Therefore, specifically when calculating the water cut of crude oil, the corresponding density can be substituted into the above formula. For example, when measuring the water cut of heavy crude oil, the density of heavy crude oil is substituted into the above formula.

[0076] In the crude oil water content detection method based on a spiral optical fiber probe provided by an embodiment of the present invention, a superhydrophobic and superoleophobic material is sprayed on the inner wall of the container for holding crude oil. Utilizing the characteristics that pure petroleum and water have different densities and are completely immiscible, when the crude oil is placed in the container, the oil and water can be naturally separated with the oil on top and the water at the bottom. One or more spiral optical fiber probes made of single-mode optical fibers are dispersedly placed in the container; the surface of the spiral optical fiber probe is also sprayed with a superhydrophobic and superoleophobic material, which will not cause liquid to adhere to the wall and is also conducive to the separation of oil and water. Since the effective refractive index of a single-mode optical fiber depends on the refractive index of the surrounding medium, when the spiral optical fiber probe is immersed in the liquid with separated oil and water, the refractive index of the segment located in the water is shifted to a certain extent under the influence of water, and the refractive index of the segment located in the pure petroleum is shifted to a different extent under the influence of pure petroleum. At this time, these two segments can be regarded as two independent gratings of the spiral optical fiber probe. The refractive index of the entire spiral optical fiber probe depends on the length ratio of these two gratings. When the crude oil has different water-oil ratios, the length ratios of these two gratings are different. Therefore, based on the detection spectral data of the light wave reflected or transmitted from the spiral optical fiber probe, the liquid level height and the height of the oil-water interface in the container can be determined. Correspondingly, knowing the liquid level height and the height of the oil-water interface, it is easy to calculate the volumes of pure petroleum and water, and thus calculate the water content of the crude oil.

[0077] In summary, compared with the prior art, the detection method provided by the embodiment of the present invention only needs to extract one spectral data for one detection of the water content of crude oil, which takes less time; moreover, the calculation method for calculating the water content of crude oil according to the liquid level height and the height of the oil-water interface in the embodiment of the present invention is relatively simple, so the detection speed is faster. On the basis of the fast detection speed, the embodiment of the present invention can continuously perform detection, so as to achieve the effect of real-time monitoring of the water content of crude oil in the container.

[0078] In addition, when the volume of the container is relatively large, the embodiment of the present invention can arrange multiple spiral optical fiber probes in the container, and these probes can be detected separately; by comparing the detection results of each probe, a more accurate and reliable water content of crude oil can be obtained.

[0079] The inventor also found in the process of implementing the present invention that, under the condition that the external medium remains unchanged, the optical properties of spiral optical fiber probes with different structural parameters (mainly pitch and axis radius) are different; that is to say, by adjusting the structural parameters of the spiral optical fiber probe, the intensity and range of the light wave output by the spiral optical fiber probe can be adjusted. Therefore, in order to make the light wave output by the spiral optical fiber probe better detected by the spectrometer, when designing the structural parameters of the spiral optical fiber probe in advance, the attenuation coefficient of the spiral optical fiber probe in the air can be made less than a preset upper limit, and the difference between the attenuation coefficient in the air and the attenuation coefficient in the liquid is greater than a preset lower limit.

[0080] Among them, the upper limit is determined according to the detection sensitivity of the spectrometer; the lower limit is determined according to the detection accuracy of the spectrometer; the detection sensitivity can be understood as the ability of the spectrometer to detect small signals, and the detection accuracy can be understood as the ability of the spectrometer to distinguish similar but different signals.

[0081] Specifically, the specific implementation method for determining the upper limit according to the detection sensitivity of the spectrometer includes: making the magnitude of the light wave containing useful information (crude oil water content information) output by the spiral optical fiber probe at least greater than the minimum signal that the spectrometer can detect.

[0082] The specific implementation method for determining the lower limit according to the detection accuracy of the spectrometer includes: at the required detection accuracy of the crude oil water content (such as 0.1%, 1%, or 5%, etc.), making the magnitudes of the light waves output by the spiral optical fiber probe for crude oils with adjacent water contents different, and this difference can be recognized and distinguished by the spectrometer. For example, assume that the required detection accuracy of the crude oil water content is 1%. Assume that the amplitude of the light wave output by the spiral optical fiber probe for crude oil with a water content of 1% is A, the amplitude of the light wave output for crude oil with a water content of 2% is B, and the amplitude of the light wave output for crude oil with a water content of 3% is C; also assume that the spectrometer can only distinguish light waves with an amplitude difference of at least 5. Then, the designed spiral optical fiber probe should make B - A and C - B both greater than 5.

[0083] In practical applications, a mechanical stepping platform and a heater can be used to prepare the spiral optical fiber probe. Among them, the mechanical stepping platform includes a rotating platform and a translation stage; the translation stage is used to move the single - mode optical fiber parallelly, so as to contact the heater segmentally to generate thermal deformation; the rotating platform is used to rotate the single - mode optical fiber, so as to prepare a regular spiral shape.

[0084] For example, fix the single - mode optical fiber in the heater and twist it 20 turns, set the heating temperature of the heater to 1300 °C to soften and twist the single - mode optical fiber. Then, start the mechanical stepping platform to perform thermal processing on the optical fiber, set the speed of the rotating platform to 36° / s and the speed of the translation stage to 50 μm / s to ensure a uniform design spacing of 500 μm during the manufacturing process.

[0085] It should be noted that the process parameters for preparing the spiral optical fiber probe shown here are only examples, and can be flexibly adjusted according to design requirements in practice, and are not limited in the embodiments of the present invention.

[0086] In an optional implementation manner, on the basis that the spiral optical fiber probe can meet the above - mentioned upper limit and lower limit, in order to reduce the possibility of liquid retention and wall - hanging caused by the spiral structure of the spiral optical fiber probe, the spiral optical fiber probe can further meet the following conditions:

[0087] The ratio of the axial radius to the pitch of the spiral optical fiber probe does not exceed 1.

[0088] It can be understood that the spiral optical fiber probe with the ratio of the axial radius to the pitch not exceeding 1 is straighter, so it is not easy to cause liquid to stay on the wall.

[0089] In addition, when multiple spiral optical fiber probes are arranged in the container, if the detection channels of the laser light source and the spectrometer are limited, by switching the connection optical path, the water content of the crude oil in different containers and the crude oil at different positions in the same container can be detected respectively.

[0090] Preferably, the above laser light source may include multiple ones, and the spectrometer may also include multiple detection channels; moreover, the number of the laser light sources and the number of the detection channels both match the number of the spiral optical fiber probes. In this way, the crude oil water content detection method provided by the embodiment of the present invention can synchronously detect the water content of the crude oil at multiple position points in the container. At this time, since each detection result is generated simultaneously, the comparison has better time consistency, and the finally determined detection result is more credible.

[0091] Based on the same inventive concept, the embodiment of the present invention also provides a crude oil water content detection system based on a spiral optical fiber probe. As shown in Fig. 3 or Figure 4 shown, the system includes: a container for containing crude oil, a laser light source, a spectrometer, and a data processing module.

[0092] Wherein, one or more segments of spiral optical fiber probes made of single-mode optical fibers are dispersedly placed in the container; these spiral optical fiber probes are perpendicular to the bottom surface of the container and in contact with the bottom surface; the heights of these spiral optical fiber probes are not lower than the height of the container; the inner wall of the container and the surface of the spiral optical fiber probes are both sprayed with superhydrophobic and superoleophobic materials to promote the upper and lower separation of oil and water in the crude oil.

[0093] The laser light source is used to input light waves into the spiral optical fiber probe after the upper and lower separation of oil and water is achieved.

[0094] The spectrometer is used to detect the light waves reflected or transmitted from the spiral optical fiber probe to obtain detection spectral data.

[0095] The data processing module is used to determine the current liquid level height and the height of the oil-water interface in the container based on the detection spectral data, and is also used to calculate the water content of the crude oil based on the liquid level height and the height of the oil-water interface.

[0096] For the specific processing process of the data processing module, reference can be made to steps S40 and S50 in the method embodiment, which will not be elaborated here.

[0097] In practical applications, the data processing module can be a computer or other circuit modules integrated with a processor. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0098] Optionally, the crude oil water content detection system provided by the embodiments of the present invention may further include: a temperature sensor; the temperature sensor is connected to the data processing module and is used to detect the ambient temperature.

[0099] Correspondingly, when calculating the water content of crude oil in the manner in step S50 above, the data processing module can first determine the water density and pure petroleum density at the ambient temperature, and then substitute these two parameters into the calculation formula for calculation.

[0100] Optionally, in the crude oil water content detection system provided by the embodiments of the present invention, there can be multiple containers in which the spiral optical fiber probes are placed. In this way, referring to the above-mentioned usage mode of switching the connection optical path, the detection system provided by the embodiments of the present invention can be used to detect the water content of crude oil in multiple containers and more position points. Or, when the number of laser light sources and the number of detection channels of the spectrometer are sufficient, the detection system provided by the embodiments of the present invention can be used to detect the water content of crude oil in multiple containers and all position points simultaneously.

[0101] It should be noted that for the system embodiments, since they are basically similar to the method embodiments, the description is relatively simple. For the relevant parts, refer to the partial description of the system embodiments, and the embodiments of the present invention will not be elaborated herein.

[0102] In the description of this specification, "a plurality of" means two or more, unless otherwise specifically defined. Descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0103] Although the present application has been described in connection with various embodiments herein, however, in the process of implementing the claimed present application, those skilled in the art can understand and realize other variations of the disclosed embodiments by viewing the accompanying drawings, the disclosure, and the appended claims.

[0104] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for detecting the water content of crude oil based on a spiral optical fiber probe, characterized in that, Comprising: Placing the crude oil whose water content is to be detected into a container; One or more spiral optical fiber probes made of single-mode optical fiber are dispersedly placed in the container; The spiral optical fiber probe is perpendicular to the bottom surface of the container and in contact with the bottom surface; the height of the spiral optical fiber probe is not lower than the height of the container; the inner wall of the container and the surface of the spiral optical fiber probe are both sprayed with superhydrophobic and superoleophobic materials to promote the up-and-down separation of oil and water in the crude oil; After realizing the up-and-down separation of oil and water, input light waves into the spiral optical fiber probe by using a laser light source; Using a spectrometer to detect the light waves reflected or transmitted from the spiral optical fiber probe to obtain detection spectral data; Based on the detection spectral data, determining the current liquid level height and the height of the oil-water interface in the container; Calculating the water content of the crude oil based on the liquid level height and the height of the oil-water interface; 2. The crude oil water content detection method according to claim 1, characterized in that, The calculating the water content of the crude oil based on the liquid level height and the height of the oil-water interface includes: Using the liquid level height to determine the total volume of the crude oil; Using the height of the oil-water interface to determine the volume of water in the crude oil, and subtracting the volume of water from the total volume to obtain the volume of pure petroleum in the crude oil; Calculating the water content of the crude oil by using the volume of water, the volume of pure petroleum, the density of water, and the density of pure petroleum; 3. The crude oil water content detection method according to claim 2, characterized in that, It further includes the step of detecting the environmental temperature; The calculating the water content of the crude oil by using the volume of water, the volume of pure petroleum, the density of water, and the density of pure petroleum includes: Calculating the water content of the crude oil by using the volume of water, the volume of pure petroleum, the density of water corresponding to the environmental temperature, and the density of pure petroleum; 4. The crude oil water content detection method according to claim 1, characterized in that, The superhydrophobic and superoleophobic material includes: Teflon, nano-zinc oxide, or calcium alginate; 5. The crude oil water content detection method according to claim 1, characterized in that The determining the current liquid level height and the height of the oil-water interface in the container based on the detection spectral data includes: Finding a target spectral data that is closest to the detection spectral data from a plurality of experimental spectral data obtained from pre-calibration tests; Determining the liquid level height and the height of the oil-water interface set corresponding to when the target spectral data is measured as the current liquid level height and the height of the oil-water interface in the container; 6. The crude oil water content detection method according to claim 1, wherein The spiral optical fiber probe satisfies the following conditions: The attenuation coefficient of the spiral optical fiber probe in air is less than a preset upper limit, and the difference between the attenuation coefficient in air and the attenuation coefficient in liquid is greater than a preset lower limit; Wherein, the upper limit is determined according to the detection sensitivity of the spectrometer, and the lower limit is determined according to the detection accuracy of the spectrometer; 7. The crude oil water content detection method according to claim 6, characterized in that, The spiral optical fiber probe further satisfies the following conditions: The ratio of the axial radius to the pitch of the spiral optical fiber probe does not exceed 1; 8. The crude oil water content detection method according to claim 1, characterized in that, There are multiple laser light sources; the spectrometer includes multiple detection channels; The number of the laser light sources and the number of the detection channels both match the number of the spiral optical fiber probes; 9. An oil - water content detection system based on a spiral optical fiber probe, characterized in that, Comprising: A container for holding crude oil; One or more segments of spiral optical fiber probes made of single-mode optical fiber are dispersedly placed in the container; The spiral optical fiber probe is perpendicular to and in contact with the bottom surface of the container; the height of the spiral optical fiber probe is not less than the height of the container; the inner wall of the container and the surface of the spiral optical fiber probe are both sprayed with a superhydrophobic and superoleophobic material to promote the up-and-down separation of oil and water in the crude oil; A laser light source; the laser light source is used to input light waves into the spiral optical fiber probe after the up-and-down separation of oil and water is achieved; A spectrometer; the spectrometer is used to detect the light waves reflected or transmitted from the spiral optical fiber probe to obtain detection spectral data; A data processing module; the data processing module is used to determine the current liquid level height and the height of the oil-water interface in the container based on the detection spectral data, and is also used to calculate the water content of the crude oil based on the liquid level height and the height of the oil-water interface.

10. The crude oil water content detection system according to claim 9, characterized in that, There are multiple containers in which the spiral optical fiber probe is placed.

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