Method for dynamically measuring water content of emulsified oil

Abstract

Disclosed in the present invention is a method for dynamically measuring water content of an emulsified oil, comprising: (1) on-site calibration: performing oil-water separation on an emulsified oil, respectively measuring M(n)oil and M(n)water, and calculating a hydrogen index of the oil, i.e., HIoil=M(n)oil / M(n)water; (2) real-time measurement: dividing a fluid in an emulsified oil pipeline into n layers in a direction perpendicular to the flow direction of the fluid, using a magnetic resonance probe to perform layer-by-layer scanning, collecting the maximum amplitude M(n) of FID on each layer, and calculating water content η(n) on each layer according to M(n)=η(n)×M(n)water / n+[1-η(n)]M(n)water×HIoil / n; and (3) calculating dynamic water content according to η=η(1)×S(1)+η(2)×S(2)+…+η(n)×S(n), wherein n is an integer selected from 2-15. In this way, a rapid, green and non-intrusive test of the water content of the emulsified oil is realized.

Description

Dynamic detection method of water content in emulsified oil

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202311747512.X filed on December 18, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of online water content detection of emulsified oil, and in particular to a dynamic detection method for the water content of emulsified oil. Background Art

[0004] In the field of petroleum industry, with the increasing depletion of conventional oil and gas resources and the deepening development of unconventional oil and gas resources, the underground fluids faced by the field of oil drilling and production engineering are mainly oil-water two-phase mixed fluids. Among them, shale oil and heavy oil, which are important unconventional oil and gas resources, have very serious emulsification phenomena. They are in the state of oil-in-water and water-in-oil in pipelines for a long time, which brings great difficulties to oil and gas metering and testing. Separation and metering technology: Conventional phase separation technology (such as three-phase separators relying on natural stratification or mechanical devices to assist stratification) cannot achieve perfect separation of oil phase and water phase, which will bring difficulties to the next step of using single-phase flowmeter for online oil and water metering and testing; sampling and testing technology: After the sample is left to stand for a period of time, the preliminary water content is read after the oil and water are separated, and then the oil-water mixed phase fluid is further demulsified with a demulsifier, and then the oil and water content of the treated fluid is measured to correct the preliminary water content data. From the above two types of on-site testing methods for the water content of emulsified oil, it can be seen that the most reliable method for testing the water content of emulsified oil is currently the sampling testing technology.

[0005] The current sampling and testing technology for water content in emulsified oil has many shortcomings:

[0006] (1) Low accuracy: ① It often takes a while to collect samples and conduct testing in a professional laboratory. During this process, the fluid physical parameters are affected by the external environment temperature, pressure, and vibration, and will undergo significant changes; ② The demulsification process during the test cannot guarantee the complete separation of oil and water, and the parameter correction itself will introduce errors; ③ The human influence factor is large, the operation process is cumbersome, and human errors will be introduced;

[0007] (2) Low efficiency and long sampling cycle. Due to the long testing time and high cost, the highest sampling frequency is more than 2 hours. The larger sampling interval cannot fully reflect the real-time dynamic changes of the oil well.

[0008] (3) Additional labor costs: The sampling and testing processes require professional personnel to operate, which results in high labor costs.

[0009] (4) Sample contamination. Adding chemical reagents such as demulsifiers during sample testing will cause contamination to the sample. The sample needs to be detoxified after testing, which causes additional costs. There is an urgent need for efficient, accurate, green and safe measurement methods.

[0010] The testing of water content in emulsified oil is a difficult problem that has plagued the petroleum industry and progress has been slow.

[0011] Low-field nuclear magnetic resonance (NMR) is currently a mainstream indoor fluid composition analysis technique. Its advantages lie in its non-invasive, environmentally friendly, efficient, and accurate measurement method, making it a promising candidate for online analysis of emulsified oils in industrial settings. However, the practical application of low-field NMR for emulsified oil moisture content analysis primarily relies on traditional static sampling methods. Online measurement is slow and inaccurate, hindering production processes. Summary of the Invention

[0012] The purpose of the present invention is to overcome the problems of slow dynamic detection process and low precision of water content in emulsified oil using low-field nuclear magnetic resonance technology in the prior art, and to provide a dynamic detection method for water content in emulsified oil.

[0013] In order to achieve the above object, the present invention provides a method for dynamically detecting the water content of emulsified oil, which comprises the following steps:

[0014] (1) On-site calibration: Separate the emulsified oil into oil and water, and measure the maximum FID value of pure oil and pure water, i.e. M(n) 油 and M(n) 水 , and calculate the hydrogen index HI of the oil 油 =M(n) 油 / M(n) 水 ;

[0015] (2) Real-time measurement: In the direction perpendicular to the fluid flow, the fluid in the emulsified oil pipeline is divided into n layers, and the magnetic resonance probe is used for layered scanning. The maximum FID amplitude M(n) is collected for each layer, and the maximum FID amplitude M(n) is calculated according to M(n) = η(n) × M(n). 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content η(n) of each layer;

[0016] (3) Calculate the dynamic moisture content according to η = η(1) × S(1) + η(2) × S(2) + ... + η(n) × S(n), where S(n) is the ratio of the volume of the nth layer to the total volume;

[0017] wherein n is selected from an integer of 2-15.

[0018] Through the above technical solution, the present invention provides a dynamic detection method for the water content of emulsified oil, which realizes the application of low-field magnetic resonance fluid detection technology to industrial measurement sites, and can use low-field nuclear magnetic resonance technology to perform dynamic measurement of the water content of emulsified oil and calibrate the hydrogen index HI of the oil. 油 Then, the maximum FID amplitude M(n) is collected by layered scanning, and M(n)=η(n)×M(n) 水 / n+[1-η(n)]M(n) 水 ×HI 油 / n calculates the moisture content η(n) of each layer, and then combines η=η(1)×S(1)+η(2)×S(2)+…+η(n)×S(n) to calculate the dynamic moisture content, thus realizing rapid, green, non-invasive and full-scale testing of the moisture content of emulsified oil. A complete testing solution including sampling method, measurement method, calibration method and sample post-processing method is provided to facilitate accurate and rapid testing of the moisture content of emulsified oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of horizontal tube layered scanning. DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0021] The present invention provides a method for dynamically detecting the water content of emulsified oil, which comprises the following steps:

[0022] (1) On-site calibration: Separate the emulsified oil into oil and water, and measure the maximum FID value of pure oil and pure water, i.e. M(n) 油 and M(n) 水 , and calculate the hydrogen index HI of the oil 油 =M(n) 油 / M(n) 水 ;

[0023] (2) Real-time measurement: In the direction perpendicular to the fluid flow, the fluid in the emulsified oil pipeline is divided into n layers, and the magnetic resonance probe is used for layered scanning. The maximum FID amplitude M(n) is collected for each layer, and the maximum FID amplitude M(n) is calculated according to M(n) = η(n) × M(n). 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content η(n) of each layer;

[0024] (3) Calculate the dynamic moisture content according to η = η(1) × S(1) + η(2) × S(2) + ... + η(n) × S(n), where S(n) is the ratio of the volume of the nth layer to the total volume;

[0025] wherein n is selected from an integer of 2-15, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15.

[0026] In the present invention, a dynamic detection method for the water content of emulsified oil is provided. Different from the existing methods, the water content measurement is completed under the state of continuous high-speed flow of the fluid, and the low-field magnetic resonance fluid detection technology is applied to the industrial measurement site. The low-field nuclear magnetic resonance technology can be used to perform dynamic determination of the water content of emulsified oil, realizing rapid, green, non-invasive, and full-scale testing of the water content of emulsified oil. A complete set of testing solutions including sampling methods, measurement methods, calibration methods, and sample post-processing methods are provided to facilitate accurate and rapid testing of the water content of emulsified oil.

[0027] In step (1):

[0028] In some specific embodiments of the present invention, the on-site calibration refers to completing the detection in step (1) preferably within 1-2 hours after the emulsified oil is produced from the well. 水 and HI 油 These two parameters need to be obtained through on-site calibration, which only needs to be calibrated once before dynamic scanning. Ready-made calibration helps improve measurement accuracy.

[0029] In some embodiments of the present invention, prior to oil-water separation of the emulsified oil, sampling is performed and the sample is placed into a sample tube. The sampling method is selected from normal pressure sampling or pressure-maintained sampling. Both normal pressure sampling and pressure-maintained sampling are conventional operations in the art and will not be described in detail herein.

[0030] In some specific embodiments of the present invention, the emulsified oil comprises crude oil and water, with the water content ranging from 0.5% to 100%. The water content can be measured at any level between 0.5% and 100%. In other words, the method provided herein can accurately measure the water content of emulsified oils with a water content between 0.5% and 100% (inclusive). Unless otherwise specified, the water content herein is calculated by volume.

[0031] In some specific embodiments of the present invention, the specific operations of separating the emulsified oil from water and determining the maximum FID values ​​of the pure oil and pure water include: allowing the emulsified oil to stand to separate the oil and water; during the standing process, every 5-15 minutes, taking the surface oil phase and the bottom water phase for nuclear magnetic resonance detection to obtain a T2 spectrum; wherein, when there is only a spectral peak of <1s (second) on the T2 spectrum, it indicates that the surface oil phase contains only oil and no water, and the surface oil phase is separated to obtain pure oil; when there is only a spectral peak of ≥1s (second) on the T2 spectrum, it indicates that the bottom water phase contains only water and no oil, and the bottom water phase is separated to obtain pure water.

[0032] In the present invention, in step (1), after the oil-water separation, a CPMG pulse sequence is continuously emitted to the obtained oil phase, and a T2 spectrum is obtained by real-time inversion. When there is only a peak of <1s (second) on the T2 spectrum, that is, when the T2 spectrum shows only a single oil peak, it indicates that the oil phase is pure oil, and its FID maximum amplitude M(n) is collected. 油 Used to calculate HI 油 In step (1), after the oil-water separation, a CPMG pulse sequence is continuously emitted to the obtained water phase, and the T2 spectrum is inverted in real time. When there is only a peak of ≥1s (second) on the T2 spectrum, that is, when the T2 spectrum shows only a single water peak, it indicates that the water phase is pure water, and its FID maximum amplitude M(n) is collected. 水 Used to calculate HI 油 .

[0033] In some specific embodiments of the present invention, in step (1), the oil-water separation method is static treatment, and the temperature of the static treatment is maintained within the range of ±5°C of the temperature when the emulsified oil is produced from the wellhead. For example, when the temperature when the emulsified oil is produced from the wellhead is 80°C, the temperature of the static treatment is maintained at 80°C±5°C; when the temperature when the emulsified oil is produced from the wellhead is 30°C, the temperature of the static treatment is maintained at 30°C±5°C; the temperature of the static treatment maintains the temperature when the emulsified oil is produced from the wellhead, which helps to completely separate the oil and water, obtain pure oil and pure water phases, and ensure the accuracy of the measurement. At the same time, the magnetic field strength of the magnetic resonance magnet is different at different temperatures, and the obtained signal strength is also different. The temperature of the static treatment maintains the temperature when the emulsified oil is produced from the wellhead, so as to perform on-site calibration more accurately.

[0034] In some specific embodiments of the present invention, in step (1), the volumes of the pure oil and pure water to be measured are the same.

[0035] In some specific embodiments of the present invention, preferably, n is selected from an integer of 10-15.

[0036] In step (2),

[0037] In some specific embodiments of the present invention, the method further comprises: preheating the magnetic resonance probe to a temperature close to the temperature of the emulsified oil fluid before measuring. The term "close" in the present invention means that the temperature difference between the preheated magnetic resonance probe temperature and the temperature of the emulsified oil fluid is within ±1°C.

[0038] In some specific embodiments of the present invention, the method further comprises: before performing the layered scanning in step (2), installing a magnetic resonance device to the pipe opening to be tested, so that the emulsified oil fluid to be tested is continuously flowed through the magnetic resonance probe to complete the layered scanning. That is, the magnetic resonance probe in the magnetic resonance device completes the layered scanning while the emulsified oil fluid is continuously flowing.

[0039] In the present invention, the magnetic resonance probe divides the scanning area into n layers in the direction perpendicular to the fluid flow direction, that is, in the diameter direction of the pipe, and then collects the maximum FID amplitude M(n) of each layer. In combination with M(n) in step (1), 水 and HI 油 Calculate the moisture content of each layer η(n). M(1)=η(1)×M(n) 水 / n+[1-η(1)]M(n) 水 ×HI 油 / n M(2)=η(2)×M(n) 水 / n+[1-η(2)]M(n) 水 ×HI 油 / n M(3)=η(3)×M(n) 水 / n+[1-η(3)]M(n) 水 ×HI 油 / n

[0040] And so on, until M(n)=η(n)×M(n) 水 / n+[1-η(n)]M(n) 水 ×HI 油 / n. Among them, in M ​​(n) = η (n) × M (n) 水 / n+[1-η(n)]M(n) 水 ×HI 油 / n, the n in the denominator represents the total number of layers, M(n) 水 represents M(n) measured in step (1) 水 .

[0041] In some specific embodiments of the present invention, in step (2), the layered scanning method is a static magnetic field gradient combined with antenna frequency modulation or a gradient coil combined with antenna frequency modulation.

[0042] Among them, in the present invention, the scanning method of static magnetic field gradient combined with antenna frequency modulation refers to applying a gradient magnetic field to the fluid in the antenna detection area, so that the fluid in different layers exhibits different resonance frequencies, and then by sequentially changing the frequency of the radio frequency pulses emitted by the radio frequency antenna, nuclear magnetic resonance occurs in the fluid in different layers, thereby realizing the sequential collection of nuclear magnetic resonance echo signals in different fluid layers.

[0043] In step (3):

[0044] In some specific embodiments of the present invention, S(n) refers to the ratio of the scan volume of the nth layer to the total scan volume of n layers.

[0045] In the present invention, S(n) can be calculated directly by a computer or by using an equal division method. The scanning area of ​​the MRI probe is a cylindrical section. The height of the cylinder is equal to the length of the pipe covered by the wound antenna, and the diameter of the cylinder is equal to the diameter of the pipe. S(n) is also equal to the ratio of the area of ​​each portion of the pipe's cross-sectional area, divided equally along the diameter, to the cross-sectional area of ​​the cylinder, as shown in Figure 1.

[0046] In some specific embodiments of the present invention, in step (2), the measurement method of S(n) is as follows: for example, n=4, that is, scanning is performed in 4 layers, each layer has a height of h, and S(1) to S(4) are calculated, S(2)=S(3)=[arcsin(h / r)*πr2 / 360+(r2-h2)1 / 2*h / 2]*v; S(1)=S(4)=[πr2 / 2-arcsin(h / r)*πr2 / 360+(r2-h2)1 / 2*h / 2]*v;

[0047] Where r is the pipe radius and v is the fluid velocity.

[0048] In the present invention, no chemical reagents are added during the entire magnetic resonance detection process, and the probe does not contact the sample during the measurement process, so there is no contamination of the sample. After the test is completed, the sample can be directly injected back into the fluid tube.

[0049] The present invention will be described in detail below through examples.

[0050] In the following examples and comparative examples, if no specific conditions are specified, the experiments shall be carried out under conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be obtained through commercial channels. The magnetic resonance equipment is the high-performance telemetry magnetic resonance microanalyzer LIME-MRI-D2 produced by Beijing Qingmeng Aike Technology Co., Ltd., which has the ability to measure CPMG pulse sequence, FID (free decay signal), automatic inversion of T2 spectrum, and layered scanning. The layered scanning method is static magnetic field gradient combined with antenna frequency modulation, with a minimum echo interval of ≤200us and a magnetic field inhomogeneity of ≤100ppm. On-site calibration refers to the completion of the detection in step (1) on the emulsified oil extracted from the wellhead within 2 hours. The sampling method of the emulsified oil is normal pressure sampling, and the measurement volume of pure oil and pure water is the same.

[0051] Example 1

[0052] Emulsified oil composition: Emulsified oil contains crude oil and water.

[0053] (1) On-site calibration: The emulsified oil is allowed to stand to separate the oil and water. The CPMG pulse sequence is continuously emitted to the obtained oil phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single oil peak, it indicates that the oil phase is pure oil. The maximum FID amplitude M(n) is collected. 油 Used to calculate HI 油 At the same time, the CPMG pulse sequence is continuously emitted to the obtained water phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single water peak, it means that the water phase is pure water, and its FID maximum amplitude M(n) is collected. 水 Used to calculate HI 油 , and calculate the hydrogen index HI of the oil 油 =M(n) 油 / M(n) 水 ;

[0054] (2) Real-time measurement: The magnetic resonance device is installed at the wellhead to be measured, and the emulsified oil fluid to be measured is scanned while continuously flowing through the magnetic resonance probe. The fluid in the emulsified oil pipeline is spatially divided into 15 layers in the direction perpendicular to the fluid flow (as shown in Figure 1). The magnetic resonance probe is used for layered scanning, and the maximum FID amplitude M(n) is collected for each layer. The maximum FID amplitude M(n) is calculated according to M(n) = η(n) × M(n). 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content η(n) of each layer;

[0055] (3) Calculate the dynamic moisture content according to η = η(1) × S(1) + η(2) × S(2) + ... + η(15) × S(15).

[0056] Example 2

[0057] The water content of the emulsified oil of Example 1 was measured:

[0058] (1) On-site calibration: The emulsified oil is allowed to stand to separate the oil and water. The CPMG pulse sequence is continuously emitted to the obtained oil phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single oil peak, it indicates that the oil phase is pure oil. The maximum FID amplitude M(n) is collected. 油 Used to calculate HI 油 At the same time, the CPMG pulse sequence is continuously emitted to the obtained water phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single water peak, it means that the water phase is pure water, and its FID maximum amplitude M(n) is collected. 水 Used to calculate HI 油 , and calculate the hydrogen index HI of the oil 油 =M(n) 油 / M(n) 水 ;

[0059] (2) Real-time measurement: The magnetic resonance device is installed at the wellhead to be measured, and the emulsified oil fluid to be measured is scanned while continuously flowing through the magnetic resonance probe. The fluid in the emulsified oil pipeline is spatially divided into 13 layers in the direction perpendicular to the fluid flow (as shown in Figure 1). The magnetic resonance probe is used for layered scanning, and the maximum FID amplitude M(n) is collected for each layer. The maximum FID amplitude M(n) is calculated according to M(n) = η(n) × M(n). 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content η(n) of each layer;

[0060] (3) Calculate the dynamic moisture content according to η = η(1) × S(1) + η(2) × S(2) + ... + η(13) × S(13).

[0061] Example 3

[0062] The water content of the emulsified oil of Example 1 was measured:

[0063] (1) On-site calibration: The emulsified oil is allowed to stand to separate the oil and water. The CPMG pulse sequence is continuously emitted to the obtained oil phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single oil peak, it indicates that the oil phase is pure oil. The maximum FID amplitude M(n) is collected. 油 Used to calculate HI 油 At the same time, the CPMG pulse sequence is continuously emitted to the obtained water phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single water peak, it means that the water phase is pure water, and its FID maximum amplitude M(n) is collected. 水 Used to calculate HI 油, and calculate the hydrogen index HI of the oil 油 =M(n) 油 / M(n) 水 ;

[0064] (2) Real-time measurement: The magnetic resonance device is installed at the wellhead to be measured, and the emulsified oil fluid to be measured is scanned while continuously flowing through the magnetic resonance probe. The fluid in the emulsified oil pipeline is spatially divided into 10 layers in the direction perpendicular to the fluid flow (as shown in Figure 1). The magnetic resonance probe is used for layered scanning, and the maximum FID amplitude M(n) is collected for each layer. The maximum FID amplitude M(n) is calculated according to M(n) = η(n) × M(n). 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content η(n) of each layer;

[0065] (3) Calculate the dynamic moisture content according to η = η(1) × S(1) + η(2) × S(2) + ... + η(10) × S(10).

[0066] Example 4

[0067] The water content of the emulsified oil of Example 1 was measured:

[0068] (1) On-site calibration: The emulsified oil is allowed to stand to separate the oil and water. The CPMG pulse sequence is continuously emitted to the obtained oil phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single oil peak, it indicates that the oil phase is pure oil. The maximum FID amplitude M(n) is collected. 油 Used to calculate HI 油 At the same time, the CPMG pulse sequence is continuously emitted to the obtained water phase, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single water peak, it means that the water phase is pure water, and its FID maximum amplitude M(n) is collected. 水 Used to calculate HI 油 , and calculate the hydrogen index HI of the oil 油 =M(n) 油 / M(n) 水 ;

[0069] (2) Real-time measurement: The magnetic resonance device is installed at the wellhead to be measured, and the emulsified oil fluid to be measured is scanned while continuously flowing through the magnetic resonance probe. The fluid in the emulsified oil pipeline is spatially divided into five layers in the direction perpendicular to the fluid flow (as shown in Figure 1). The magnetic resonance probe is used for layered scanning, and the maximum FID amplitude M(n) is collected for each layer. The maximum FID amplitude M(n) is calculated according to M(n) = η(n) × M(n). 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content η(n) of each layer;

[0070] (3) Calculate the dynamic moisture content according to η = η(1) × S(1) + η(2) × S(2) + ... + η(5) × S(5).

[0071] Comparative Example 1

[0072] The water content of the emulsified oil of Example 1 was measured: the emulsified oil sample was collected at the wellhead using a sampling bucket and brought to the laboratory, and the water content of the fluid was obtained by electrical dehydration testing.

[0073] Evaluation method: Determine the comprehensive water content of the fluid flowing through the pipeline for 1 hour: Connect a flow meter and a three-phase separator in series. Use the three-phase separator to separate the multiphase flow of the emulsified oil fluid into single phases. Then use a water flow meter, an oil flow meter, and a gas flow meter to measure the comprehensive water content of the fluid (i.e., the actual water content). Compare this to the average dynamic water content obtained within 1 hour (measured every 30 minutes) in this example. The average dynamic water content is the average of the dynamic water contents obtained within 1 hour in this example. For comparative example 1, samples were taken and measured for 24 hours to obtain the measurement results. The results are shown in Table 1. The closer the average dynamic water content is to the comprehensive water content, the more accurate the measurement result.

[0074] Table 1

[0075] It can be seen from the results in Table 1 that the method adopted in the embodiment of the present invention has higher detection accuracy, can use low-field nuclear magnetic resonance technology to perform dynamic determination of the water content of emulsified oil, and realize rapid, green, non-invasive, and full-scale detection of the water content of emulsified oil.

[0076] Example 5

[0077] The water content of the emulsified oil produced from the wellhead of a production well in a shale oil development field was measured.

[0078] (1) On-site calibration: The temperature of the emulsified oil at the wellhead is 23°C. The emulsified oil is allowed to stand at 23±5°C to separate the oil and water. During the standing process, the surface oil phase and the bottom water phase are sampled every 10 minutes for nuclear magnetic resonance (NMR) testing.

[0079] The surface oil phase and bottom water phase were removed and added separately to NMR sample tubes. CPMG pulse sequences were continuously emitted, and T2 spectra were inverted in real time. A T2 spectrum with a peak duration of <1 second indicated that the surface oil phase contained only oil, with no water. A T2 spectrum with a peak duration of ≥1 second indicated that the bottom water phase contained only water, with no oil.

[0080] Repeatedly sample the surface oil phase until there is only a peak <1s (second) on the T2 spectrum, then separate the surface oil phase to obtain pure oil; place the pure oil in an NMR sample tube, and use the magnetic resonance probe in the magnetic resonance equipment to measure the maximum FID amplitude of the pure oil in the tube, i.e., M(n) 油 =146.8μV;

[0081] Repeatedly sample the bottom water phase until only a peak of ≥1s (second) is observed on the T2 spectrum. Then separate the bottom water phase to obtain pure water. Place the pure water in an NMR sample tube and use the magnetic resonance probe in the magnetic resonance equipment to measure the maximum FID amplitude of the pure water in the tube, i.e., M(n). 水 =151.3μV;

[0082] HI 油 =M(n) 油 / M(n) 水 =146.8μV / 151.3μV=0.97;

[0083] (2) Real-time measurement: In the wellhead to be measured, the radius of the pipe is 40 mm, the flow rate of the emulsified oil fluid is 0.8 m / s, and the temperature of the emulsified oil is 23°C; the magnetic resonance equipment is installed at the wellhead to be measured, and after the magnetic resonance probe in the magnetic resonance equipment is preheated to 23°C, the flowing emulsified oil fluid is scanned in layers in a direction perpendicular to the flow direction of the fluid using the magnetic resonance probe. The layers are divided into two layers, and the maximum FID amplitude M(n) is collected in each layer. From top to bottom, M(1) is 73.9 μV, and M(2) is 75.6 μV.

[0084] According to M(n)=η(n)×M(n) 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content of each layer η(n), where M(1)=η(1)×M(n) 水 / n+[1-η(1)]M(n) 水 ×HI 油 / n 73.9μV=η(1)×151.3μV / 2+[1-η(1)]×151.3μV×0.97 / 2 η(1)=0.229=22.9% M(2)=η(2)×M(n) 水 / n+[1-η(2)]M(n) 水 ×HI 油 / n 75.6μV=η(2)×151.3μV / 2+[1-η(2)]×151.3μV×0.97 / 2 η(2)=0.978=97.8%

[0085] (3) From top to bottom, S(1)=S(2)=0.5, and the dynamic water content is calculated according to η=η(1)×S(1)+η(2)×S(2), η=0.229*0.5+0.978*0.5=60.4%.

[0086] Comparative Example 2

[0087] At the same time as in Example 5, the emulsified oil sample was collected through the sampling barrel, and then the water content was tested indoors: the emulsified oil sample collected in Example 5 was transported to the laboratory, and the water content of the fluid was 59.8% obtained by electric dehydration.

[0088] Among them, by comparing the results of Example 5 and Comparative Example 2, it can be seen that the moisture content measured in Example 5 and the moisture content measured in Comparative Example 2 differ by only 0.6%, which shows that the moisture content testing method provided in the present invention has high accuracy.

[0089] Example 6

[0090] The water content of the emulsified oil produced from the wellhead of a production well in a shale oil development field was measured.

[0091] (1) On-site calibration: The temperature of the emulsified oil at the wellhead is 20°C. The emulsified oil is allowed to stand at 20±5°C to separate the oil and water. During the standing process, the surface oil phase and the bottom water phase are sampled every 10 minutes for nuclear magnetic resonance (NMR) testing.

[0092] The surface oil phase and bottom water phase were removed and added separately to NMR sample tubes. CPMG pulse sequences were continuously emitted, and T2 spectra were inverted in real time. A T2 spectrum with a peak duration of <1 second indicated that the surface oil phase contained only oil, with no water. A T2 spectrum with a peak duration of ≥1 second indicated that the bottom water phase contained only water, with no oil.

[0093] Repeatedly sample the surface oil phase until there is only a peak <1s (second) on the T2 spectrum, then separate the surface oil phase to obtain pure oil; place the pure oil in an NMR sample tube, and use the magnetic resonance probe in the magnetic resonance equipment to measure the maximum FID amplitude of the pure oil in the tube, i.e., M(n) 油 =145μV;

[0094] Repeatedly sample the bottom water phase until only a peak of ≥1s (second) is observed on the T2 spectrum. Then separate the bottom water phase to obtain pure water. Place the pure water in an NMR sample tube and use the magnetic resonance probe in the magnetic resonance equipment to measure the maximum FID amplitude of the pure water in the tube, i.e., M(n). 水 =151μV; HI 油 =M(n) 油 / M(n) 水 =145μV / 151μV=0.96;

[0095] (2) Real-time measurement: In the wellhead to be measured, the radius of the pipe is 40 mm, the flow rate of the emulsified oil fluid is 1 m / s, and the temperature of the emulsified oil is 20°C; the magnetic resonance equipment is installed at the wellhead to be measured, and after the magnetic resonance probe in the magnetic resonance equipment is preheated to 20°C, the flowing emulsified oil fluid is scanned in layers using the magnetic resonance probe in a direction perpendicular to the flow direction of the fluid. The layers are divided into 4 layers, and the maximum FID amplitude M(n) is collected in each layer. From top to bottom, M(1) is 36.6 μV, M(2) is 36.9 μV, M(3) is 37.4 μV, and M(4) is 37.5 μV.

[0096] According to M(n)=η(n)×M(n) 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content of each layer η(n), where M(1)=η(1)×M(n) 水 / n+[1-η(1)]×M(n) 水 ×HI 油 / n 36.6μV=η(1)×151μV / 4+[1-η(1)]×151μV×0.96 / 4 η(1)=0.238=23.8% M(2)=η(2)×M(n) 水 / n+[1-η(2)]×M(n) 水 ×HI 油 / n 36.9μV=η(2)×151μV / 4+[1-η(2)]×151μV×0.96 / 4 η(2)=0.437=43.7% M(3)=η(3)×M(n) 水 / n+[1-η(3)]×M(n) 水 ×HI 油 / n 37.4μV=η(3)×151μV / 4+[1-η(3)]×151μV×0.96 / 4 η(3)=0.768=76.8% M(4)=η(4)×M(n) 水 / n+[1-η(4)]×M(n) 水 ×HI 油 / n 37.5μV=η(4)×151μV / 4+[1-η(4)]×151μV×0.96 / 4 η(4)=0.834=83.4%

[0097] (3) From top to bottom, S(1) = S(4) = 0.1999, S(2) = S(3) = 0.302, and the dynamic water content is calculated according to η = η(1) × S(1) + η(2) × S(2) + η(3) × S(3) + η(4) × S(4), η = 0.238 × 0.199 + 0.437 × 0.302 + 0.768 × 0.302 + 0.834 × 0.199 = 57.7%.

[0098] Comparative Example 3

[0099] At the same time as in Example 6, the emulsified oil sample was collected through the sampling barrel, and then the water content was tested indoors: the emulsified oil sample collected in Example 6 was transported to the laboratory, and the water content of the fluid was 58.1% obtained by electric dehydration testing.

[0100] Among them, by comparing the results of Example 6 and Comparative Example 3, it can be seen that the moisture content measured in Example 6 and the moisture content measured in Comparative Example 3 differ by only 0.4%, which shows that the moisture content testing method provided in the present invention has high accuracy.

[0101] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for dynamic detection of water content in emulsified oil, characterized in that: The steps include: (1) On-site calibration: Separate the emulsified oil into oil and water, and measure the maximum FID value of pure oil and pure water, i.e. M(n). 油 and M(n) 水 , and calculate the hydrogen index HI of the oil 油 =M(n) 油 / M(n) 水 ; (2) Real-time measurement: In the direction perpendicular to the fluid flow, the fluid in the emulsified oil pipeline is divided into n layers, and the magnetic resonance probe is used for layered scanning. The maximum FID amplitude M(n) is collected for each layer, and the maximum FID amplitude M(n) is calculated according to M(n)=η(n)×M(n). 水 / n+[1-η(n)]M(n) 水 ×HI 油 / nCalculate the moisture content η(n) of each layer; (3) Calculate the dynamic moisture content according to η = η(1) × S(1) + η(2) × S(2) + ... + η(n) × S(n), where S(n) is the ratio of the volume of the nth layer to the total volume; Wherein, n is selected from an integer of 2-15.

2. The method according to claim 1, wherein: n is selected from an integer of 10-15.

3. The method according to claim 1 or 2, wherein: The method further comprises: before measuring, preheating the magnetic resonance probe to a temperature close to that of the emulsified oil fluid.

4. The method according to claim 1, wherein: In step (1), before the emulsified oil is separated into oil and water, sampling is first performed and the sample is sampled into a sample tube. The sampling method is selected from normal pressure sampling or pressure-maintaining sampling.

5. The method according to claim 1, wherein: In step (1), the oil-water separation method is static treatment, and the temperature of the static treatment is maintained within the range of ±5°C of the temperature when the emulsified oil is produced from the wellhead.

6. The method according to claim 1, wherein: In step (1), the volumes of pure oil and pure water to be measured are the same.

7. The method according to claim 1, wherein: The method further comprises: before performing the layered scanning in step (2), installing a magnetic resonance device to the pipe opening to be tested, so that the emulsified oil fluid to be tested completes the layered scanning in the process of continuously flowing through the magnetic resonance probe.

8. The method according to claim 1, wherein: In step (2), the layered scanning method is static magnetic field gradient combined with antenna frequency modulation or gradient coil combined with antenna frequency modulation.

9. The method according to claim 1, wherein: In step (1), after the oil-water separation, the obtained oil phase is continuously emitted with a CPMG pulse sequence, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single oil peak, it indicates that the oil phase is pure oil, and the maximum FID amplitude M(n) is collected. 油 To calculate HI 油 .

10. The method according to claim 1, wherein: In step (1), after the oil-water separation, the obtained water phase is continuously emitted with a CPMG pulse sequence, and the T2 spectrum is inverted in real time. When the T2 spectrum shows only a single water peak, it indicates that the water phase is pure water, and the maximum FID amplitude M(n) is collected. 水 To calculate HI 油 .

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