Experimental device and experimental method for monitoring oil-gas-water components in shaft

Abstract

The invention discloses an experimental device and an experimental method for monitoring oil-gas-water components in a shaft, and particularly relates to the technical field of monitoring equipment.The experimental device comprises the shaft, a single-mode laser, a polarization maintaining optical fiber, a Brillouin optical time domain reflectometer, a condensate gas tank, a pressurization driving device, a stratum water tank, a condensate oil tank, a natural gas tank, a conveying device, an oil-gas-water separator and a waste oil tank; the polarization-maintaining optical fiber is spirally wound outside the shaft, and two ends of the polarization-maintaining optical fiber are respectively connected with the single-mode laser and the Brillouin optical time domain reflectometer; the pressurization driving device is used for pressurizing the condensate gas to the dew point pressure higher than that of the condensate gas and driving the condensate gas to leave the condensate gas tank; the conveying device is used for conveying formation water of the formation water tank, condensate oil of the condensate oil tank and natural gas of the natural gas tank to the shaft, and an outlet of the shaft is connected with the waste oil tank through the oil-gas-water separator. The oil-gas-water three-phase fluid in the shaft can be captured and dynamically tracked in real time, the measurement precision is high, and the experimental device is simple in structure and convenient to install.

Description

Technical Field

[0001] The present invention relates to the technical field of monitoring equipment, and in particular to an experimental device and method for monitoring oil, gas and water components in a wellbore. Background Art

[0002] During the development of condensate gas reservoirs, the actual fluid flow within the wellbore exhibits highly complex dynamic characteristics. Its flow state is affected by the synergistic influence and coupling of multiple factors, including formation energy attenuation, water cut changes, and gas-liquid ratio fluctuations. Furthermore, the oil, gas, and water three-phase fluid in the wellbore exhibits significant dynamic evolution characteristics.

[0003] However, current monitoring technologies have inherent limitations in terms of real-time performance, continuity, and accuracy. Traditional monitoring methods struggle to capture and dynamically track oil, gas, and water three-phase fluids in real time, making it difficult to meet the demands for timely identification and effective management of these fluids in actual production. Furthermore, existing indoor experimental studies are often conducted under idealized conditions such as low pressure and room temperature, significantly different from the complex working conditions of high temperature, high pressure, and strong multi-phase coupling within actual wellbores. This makes the research results obtained from these experiments challenging to apply in actual engineering applications, making it difficult to directly guide on-site production practices. Summary of the Invention

[0004] The purpose of the present invention is to provide an experimental device and experimental method for monitoring oil, gas and water components in a wellbore to solve the problems existing in the above-mentioned prior art. It can capture and dynamically track the oil, gas and water three-phase fluid in the wellbore in real time, with high measurement accuracy, simple experimental device structure and easy installation.

[0005] To achieve the above object, the present invention provides the following solutions: The present invention provides an experimental device for monitoring oil, gas and water components in a wellbore, comprising a wellbore, a single-mode laser, a polarization-maintaining optical fiber, a Brillouin optical time-domain reflectometer, a condensate gas tank, a pressurizing drive device, a formation water tank, a condensate oil tank, a natural gas tank, a conveying device, an oil-gas-water separator and a waste oil tank. The polarization-maintaining optical fiber is spirally wound outside the wellbore, the input end of the polarization-maintaining optical fiber is connected to the single-mode laser, and the output end of the polarization-maintaining optical fiber is connected to the Brillouin optical time-domain reflectometer; both ends of the wellbore are closed; the condensate gas tank is connected and communicated with the bottom of the wellbore, the condensate gas tank is used to contain condensate gas, and the pressurizing drive device is connected to the condensate gas tank. The wellbore is connected to a conveying device for pressurizing the condensate gas so that the pressure of the pressurized condensate gas is higher than the dew point pressure of the condensate gas, and driving the pressurized condensate gas to leave the condensate gas tank; the formation water tank, the condensate oil tank and the natural gas tank are all connected to and communicated with the bottom of the wellbore, and the formation water tank, the condensate oil tank and the natural gas tank are all connected to the conveying device, and the conveying device is used to convey the formation water in the formation water tank, the condensate oil in the condensate oil tank and the natural gas in the natural gas tank to the wellbore respectively, the oil-gas-water separator is connected to and communicated with the top of the wellbore, and the oil outlet of the oil-gas-water separator is connected to and communicated with the waste oil tank.

[0006] Preferably, the top of the wellbore is provided with an oil nozzle, and the oil nozzle is connected to and communicated with the oil-gas-water separator.

[0007] Preferably, it further comprises a waste water tank, the water outlet of the oil-gas-water separator is connected to and communicated with the waste water tank, and the gas outlet of the oil-gas-water separator is communicated with the outside.

[0008] Preferably, it further includes a first pressure gauge and a second pressure gauge, wherein the first pressure gauge is connected to the condensate gas tank for monitoring the pressure in the condensate gas tank, and the second pressure gauge is connected to the formation water tank for monitoring the pressure in the formation water tank.

[0009] Preferably, the pressurizing drive device includes a pressurizing piston and a piston drive device, the piston drive device is connected to the pressurizing piston, the pressurizing piston is arranged in the condensate gas tank, and the edge of the pressurizing piston is tightly fitted and slidably connected to the inner wall of the condensate gas tank.

[0010] Preferably, the conveying device is a double-cylinder pump.

[0011] Preferably, the polarization-maintaining optical fiber is fixedly adhered to the outside of the wellbore by an adhesive.

[0012] Preferably, the wellbore includes a top cover, a barrel and a bottom cover, and the top cover and the bottom cover are both threadedly connected to the barrel.

[0013] Preferably, the condensate gas tank, the formation water tank, the condensate oil tank and the natural gas tank are all made of steel.

[0014] The present invention also provides an experimental method using the above-mentioned experimental device for monitoring oil, gas and water components in a wellbore, comprising the following steps: Step 1: calibrate the fluid density parameter range and forward Brillouin scattering light frequency shift parameter range of the oil, gas and water phases respectively; Calibrate formation water: Start the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the formation water tank, and then start the conveying device to convey the formation water in the formation water tank to the wellbore at a constant pressure. The laser light from the single-mode laser is transmitted to the wellbore by the polarization-maintaining optical fiber. The laser light with the generated scattering frequency shift is then received by the Brillouin optical time-domain reflectometer through the polarization-maintaining optical fiber. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer is combined with a formula to obtain primary formation water density data. Repeat the above test to obtain multiple formation water density data to determine the formation water density range, and establish a functional relationship between the Brillouin scattered light frequency shift and the formation water density. Calibrate condensate oil: Start the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the condensate oil tank, and then start the conveying device to convey the condensate oil in the condensate oil tank to the wellbore at a constant pressure. The laser light from the single-mode laser is transmitted to the wellbore by the polarization-maintaining optical fiber. The laser light with generated scattering frequency shift is then received by the Brillouin optical time-domain reflectometer through the polarization-maintaining optical fiber. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer is combined with a formula to obtain primary condensate oil density data. Repeat the above test to obtain multiple condensate oil density data, then determine the formation water density range, and establish a functional relationship between the Brillouin scattered light frequency shift and the condensate oil density. Calibration of natural gas: Activate the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the natural gas tank, and then activate the delivery device to deliver the natural gas in the natural gas tank to the wellbore at a constant pressure. Laser light from the single-mode laser is transmitted to the wellbore by the polarization-maintaining optical fiber. The laser light, after generating a scattering frequency shift, is then received by the Brillouin optical time-domain reflectometer through the polarization-maintaining optical fiber. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer is combined with a formula to obtain primary natural gas density data. Repeat the above test to obtain multiple natural gas density data to determine the formation water density range, and establish a functional relationship between the Brillouin scattered light frequency shift and natural gas density. Step 2: After obtaining the results of the oil, gas, and water three-phase calibration, the pressurizing drive device is turned on to pressurize the condensate gas in the condensate gas tank with the outlet closed, so that the pressure of the pressurized condensate gas is higher than the dew point pressure of the condensate gas; Step 3: Turn on the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the condensate gas tank, and allow the pressurized condensate gas to flow into the wellbore. Then, start the conveying device and open the outlet valve of the formation water tank to allow the formation water to flow into the wellbore at a constant pressure. Step 4: Observe the waste oil tank, record the time T1 when the first drop of oil appears in the waste oil tank, and then observe whether the frequency shift of the forward Brillouin scattered light recorded by the Brillouin optical time domain reflectometer shows the frequency shift characteristics of the oil, gas, and water phases. If so, record the time T2 of this moment. The experiment is terminated after all the condensate gas in the condensate gas tank is discharged. After the experiment is completed, the conveying device is shut down and the wellbore is cleaned and dried. Step 5: Calculate the compositional changes of the oil, gas, and water phases from time T2 to the end of the experiment using the optical frequency shift data measured in the Brillouin optical time-domain reflectometer in combination with the previously established functional relationship between the Brillouin scattered light frequency shift and the densities of the three phases of oil, gas, and water. This can provide the compositional changes of the oil, gas, and water phases in the wellbore when the condensate gas reservoir encounters water invasion under simulated formation conditions.

[0015] Compared with the prior art, the present invention has achieved the following technical effects: The present invention provides an experimental device and method for monitoring oil, gas and water components in a wellbore. A polarization-maintaining optical fiber is spirally wound on the wellbore to form a distributed light sensor. A single-mode laser is used to inject pulsed light into the polarization-maintaining optical fiber. A Brillouin optical time-domain reflectometer is then used to detect the frequency shift of forward Brillouin scattered light in the optical fiber. Density data of the oil, gas and water phases are calculated based on the frequency shift. Finally, condensate gas is used to conduct an experiment, and the components of the oil, gas and water phases are identified based on the different density data. The experimental device has a simple structure and can be quickly installed, disassembled, cleaned and maintained. A single-mode laser, polarization-maintaining optical fiber and Brillouin optical time-domain reflectometer are used to build a An experimental device for monitoring the three components of oil, gas, and water that is not affected by mechanical factors, temperature, and pressure is established. After establishing the functional relationship between the frequency shift of Brillouin scattering light and the densities of oil, gas, and water, the proportion of a certain phase density data in the fluid in the wellbore can be determined according to the length of time it appears during the experiment. The strain measurement range of polarization-maintaining optical fiber can usually reach from micro-strain of one millionth to nano-level strain, and it is safe and reliable, does not require frequent calibration, and has higher data signal transmission capabilities, effectively reducing the error of experimental measurement data. In addition, polarization-maintaining optical fiber has strong anti-interference ability and is suitable for various complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic diagram of the structure of the experimental device for monitoring oil, gas and water components in the wellbore; Figure 2 This is an exploded view of the wellbore; Figure 3 It is a front view of the wellbore or bottom cover.

[0018] In the figure: 1-wellbore; 2-single-mode laser; 3-polarization-maintaining optical fiber; 4-Brillouin optical time-domain reflectometer; 5-condensate gas tank; 6-pressurization drive device; 7-pressurization piston; 8-formation water tank; 9-condensate oil tank; 10-natural gas tank; 11-transportation device; 12-oil-gas-water separator; 13-waste oil tank; 14-wastewater tank; 15-first pressure gauge; 16-second pressure gauge; 17-oil nozzle; 18-top cover; 19-cylinder; 20-bottom cover; 21-adhesive area; 22-screw hole. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] The purpose of the present invention is to provide an experimental device and experimental method for monitoring oil, gas and water components in a wellbore to solve the problems existing in the above-mentioned prior art. It can capture and dynamically track the oil, gas and water three-phase fluid in the wellbore in real time, with high measurement accuracy, simple experimental device structure and easy installation.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Example 1 This embodiment provides an experimental device for monitoring oil, gas and water components in a wellbore. Figure 1As shown, it includes a wellbore 1, a single-mode laser 2, a polarization-maintaining optical fiber 3, a Brillouin optical time-domain reflectometer 4, a condensate gas tank 5, a pressurizing drive device 6, a formation water tank 8, a condensate oil tank 9, a natural gas tank 10, a conveying device 11, an oil-gas-water separator 12 and a waste oil tank 13. The polarization-maintaining optical fiber 3 is spirally wound outside the wellbore 1, the input end of the polarization-maintaining optical fiber 3 is connected to the single-mode laser 2, and the output end of the polarization-maintaining optical fiber 3 is connected to the Brillouin optical time-domain reflectometer 4; both ends of the wellbore 1 are closed; the condensate gas tank 5 is connected and communicated with the bottom of the wellbore 1, and the condensate gas tank 5 is used to contain condensate gas. The pressurizing drive device 6 is connected to the condensate gas tank 5. It is used to pressurize the condensate gas so that the pressure of the pressurized condensate gas is higher than the dew point pressure of the condensate gas, and drive the pressurized condensate gas to leave the condensate gas tank 5; the formation water tank 8, the condensate oil tank 9 and the natural gas tank 10 are all connected to and communicated with the bottom of the wellbore 1, and the formation water tank 8, the condensate oil tank 9 and the natural gas tank 10 are all connected to the conveying device 11. The conveying device 11 is used to convey the formation water in the formation water tank 8, the condensate oil in the condensate oil tank 9 and the natural gas in the natural gas tank 10 to the wellbore 1 respectively. The oil-gas-water separator 12 is connected to and communicated with the top of the wellbore 1, and the oil outlet of the oil-gas-water separator 12 is connected to and communicated with the waste oil tank 13. A distributed light sensor is formed by spirally winding a polarization-maintaining optical fiber 3 on a wellbore 1. A single-mode laser 2 is used to inject pulsed light into the polarization-maintaining optical fiber 3. A Brillouin optical time-domain reflectometer 4 is then used to detect the frequency shift of the forward Brillouin scattered light in the optical fiber. The density data of the oil, gas, and water phases are calculated based on the frequency shift. Finally, condensate gas is used to conduct an experiment, and the components of the oil, gas, and water phases are identified based on the different density data. The experimental device has a simple structure and can be quickly installed, disassembled, cleaned, and maintained. A single-mode laser 2, a polarization-maintaining optical fiber 3, and a Brillouin optical time-domain reflectometer 4 are used to build a sensor that is not affected by mechanical factors and temperature pressure. An experimental device for monitoring the three components of oil, gas, and water under the influence of force is developed. After establishing the functional relationship between the frequency shift of Brillouin scattering light and the densities of oil, gas, and water, the proportion of the fluid components in the wellbore 1 can be determined based on the duration of the appearance of the density data of a certain phase during the experiment. The strain measurement range of the polarization-maintaining optical fiber 3 can generally reach from microstrain of one millionth to nano-level strain, and it is safe and reliable, without the need for frequent calibration. At the same time, it also has a higher data signal transmission capability, effectively reducing the error of the experimental measurement data. In addition, the polarization-maintaining optical fiber 3 has a strong anti-interference ability and is suitable for various complex environments.

[0023] Brillouin scattering is essentially a nonlinear scattering phenomenon in which, when an incident light wave passes through a medium, the elastic acoustic wave field within the medium interacts with the optical wave field, generating phonons or magnons, which in turn cause the scattering of photons. The frequency of the scattered light is shifted relative to the incident light. The magnitude of the Brillouin scattered light frequency shift is related to the speed of sound, which in turn is related to the elastic properties and density of the medium. Therefore, different materials can be identified by measuring the forward Brillouin scattered light frequency shift. Brillouin optical time-domain reflectometry (OTDR) utilizes this property to measure the Brillouin scattered light frequency shift.

[0024] The pressurizing drive device 6 is connected to the condensate gas tank 5 and is used to pressurize the condensate gas so that the pressure of the pressurized condensate gas is higher than the dew point pressure of the condensate gas, thereby preventing part of the gas phase in the condensate gas from condensing into a liquid phase and ensuring the accuracy of the experiment.

[0025] The formation water in the formation water tank 8 is configured with appropriate concentrations of various ions according to the formation conditions of the study area; the natural gas in the natural gas tank 10 and the condensate in the condensate tank 9 are configured according to the natural gas and crude oil samples actually produced in the study area; the condensate gas in the condensate gas tank 5 is prepared by mixing, heating and pressurizing natural gas and crude oil according to the gas-oil ratio and dew point pressure under the formation conditions of the study area, so as to reduce deviations from complex working conditions such as high temperature, high pressure, and multiphase flow in the actual wellbore 1.

[0026] It is further preferred in the implementation manner of this embodiment that an oil nozzle 17 is provided at the top of the wellbore 1 , and the oil nozzle 17 is connected to and communicated with the oil-gas-water separator 12 .

[0027] In this embodiment, the experimental device for monitoring oil, gas, and water composition in a wellbore preferably also includes a wastewater tank 14. The water outlet of the oil, gas, and water separator 12 is connected to and communicates with the wastewater tank 14, and the gas outlet of the oil, gas, and water separator 12 is communicated with the outside world. Wastewater tank 14 and waste oil tank 13 are used to store the formation water and crude oil separated by the oil, gas, and water separator 12, preventing contamination of the experimental environment and damage to the equipment. The separated natural gas is discharged directly into the atmosphere.

[0028] It is further preferred in the implementation of this embodiment that the oil, gas and water component monitoring experimental device in the wellbore also includes a first pressure gauge 15 and a second pressure gauge 16. The first pressure gauge 15 is connected to the condensate gas tank 5 for monitoring the pressure in the condensate gas tank 5, and the second pressure gauge 16 is connected to the formation water tank 8 for monitoring the pressure in the formation water tank 8.

[0029] It is further preferred in the implementation of this embodiment that the pressurizing drive device 6 includes a pressurizing piston 7 and a piston drive device, the piston drive device is connected to the pressurizing piston 7, the pressurizing piston 7 is arranged in the condensate gas tank 5, and the edge of the pressurizing piston 7 is tightly fitted and slidably connected to the inner wall of the condensate gas tank 5.

[0030] It is further preferred in the implementation of this embodiment that the conveying device 11 is a double-cylinder pump.

[0031] In the embodiment of the present invention, it is further preferred that the polarization-maintaining optical fiber 3 is fixedly adhered to the outside of the wellbore 1 by an adhesive. The wellbore 1 is uniformly spirally wound with the polarization-maintaining optical fiber 3 from top to bottom. The wellbore 1 is made of steel. Figure 1 and Figure 2 The black and white dots are the adhesive spots 21 (i.e., the spots where the polarization-maintaining optical fiber 3 is glued with adhesive). The adhesive spots 21 are evenly distributed around the shaft 1. The black dots are visible adhesive spots 21 from a primary perspective, and the white dots are invisible back adhesive spots 21 from a primary perspective. Apart from these, there is no difference between the black and white dots.

[0032] It is further preferred in the implementation manner of this embodiment that Figure 2-Figure 3 As shown, the wellbore 1 includes a top cover 18, a barrel 19, and a bottom cover 20, both of which are threadedly connected to the barrel 19. Both the top cover 18 and the bottom cover 20 of the wellbore 1 are threaded. During use, the top cover 18 and the bottom cover 20 can be tightened counterclockwise and then loosened clockwise for removal. The wellbore 1 is removable, facilitating routine maintenance and cleaning. The top cover 18 and the bottom cover 20 are identical, both having two closable screw holes 22 designed for connecting pipelines or installing other accessories (such as the nozzle 17).

[0033] It is further preferred in the implementation of this embodiment that the condensate gas tank 5 , the formation water tank 8 , the condensate oil tank 9 and the natural gas tank 10 are all made of steel.

[0034] Example 2 This embodiment provides an experimental method using the experimental device for monitoring oil, gas and water components in a wellbore according to embodiment 1, including the following steps: Step 1: calibrate the fluid density parameter range and forward Brillouin scattering light frequency shift parameter range of the oil, gas and water phases respectively; Calibrate formation water: Start the single-mode laser 2 and the Brillouin optical time-domain reflectometer 4, open only the outlet valve of the formation water tank 8, and then start the conveying device 11 to convey the formation water in the formation water tank 8 to the wellbore 1 at a constant pressure. The laser light in the single-mode laser 2 is transmitted to the wellbore 1 by the polarization-maintaining optical fiber 3. The laser light with the generated scattering frequency shift is then received by the Brillouin optical time-domain reflectometer 4 through the polarization-maintaining optical fiber 3. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer 4 is combined with formula 1 and formula 2 to obtain the formation water density data. Repeat the above test to obtain multiple formation water density data and determine the formation water density range. After the test is completed, close the single-mode laser 2, the Brillouin optical time-domain reflectometer 4, the conveying device 11 and the outlet valve of the formation water tank 8. Use the measured data to establish a functional relationship between the Brillouin scattered light frequency shift and the formation water density. Calibrate condensate oil: Start the single-mode laser 2 and the Brillouin optical time-domain reflectometer 4, open only the outlet valve of the condensate oil tank 9, and then start the conveying device 11 to convey the condensate oil in the condensate oil tank 9 to the wellbore 1 at a constant pressure. The laser light in the single-mode laser 2 is transmitted to the wellbore 1 by the polarization-maintaining optical fiber 3. The laser light with the generated scattered light frequency shift is then received by the Brillouin optical time-domain reflectometer 4 through the polarization-maintaining optical fiber 3. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer 4 is combined with formula 1 and formula 2 to obtain the primary condensate oil density data. Repeat the above test to obtain multiple condensate oil density data and determine the formation water density range. After completion, close the single-mode laser 2, the Brillouin optical time-domain reflectometer 4, the conveying device 11 and the outlet valve of the condensate oil tank 9. Based on the measured data, establish a functional relationship between the Brillouin scattered light frequency shift and the condensate oil density. Natural gas calibration: Start the single-mode laser 2 and the Brillouin optical time-domain reflectometer 4, open only the outlet valve of the natural gas tank 10, and then start the conveying device 11 to convey the natural gas in the natural gas tank 10 to the wellbore 1 at a constant pressure. The laser light from the single-mode laser 2 is transmitted to the wellbore 1 by the polarization-maintaining fiber 3. The laser light with the generated scattering frequency shift is then received by the Brillouin optical time-domain reflectometer 4 through the polarization-maintaining fiber 3. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer 4 is combined with formulas 1 and 2 to obtain the primary natural gas density data. Repeat the above test to obtain multiple natural gas density data and determine the formation water density range. After completion, close the single-mode laser 2, the Brillouin optical time-domain reflectometer 4, the conveying device 11, and the outlet valve of the natural gas tank 10. Based on the measured data, a functional relationship between the Brillouin scattered light frequency shift and the natural gas density is established. The functional relationship between the forward Brillouin scattered light frequency shift and the speed of sound is as follows: (1) in: V B is the Brillouin scattered light frequency shift, Hz; neff is the effective refractive index of the fiber core, dimensionless; V A is the speed of sound waves in the optical fiber, m / s; λ p is the pump light wavelength, m; At the same time, the speed of sound V A The functional relationship with the density ρ and elastic modulus of the material is as follows: (2) in: V A is the speed of sound waves in the optical fiber, m / s; K is the bulk Young's modulus of the fluid medium, MPa; ρ is the density of the fluid medium, kg / m 3 ; Step 2: After obtaining the results of the oil, gas, and water three-phase calibration, the pressurizing drive device 6 is turned on to pressurize the condensate gas in the condensate gas tank 5 whose outlet is closed, so that the pressure of the pressurized condensate gas is higher than the dew point pressure of the condensate gas; Step 3: Turn on the single-mode laser 2 and the Brillouin optical time-domain reflectometer 4, open the outlet valve of the condensate gas tank 5, and allow the pressurized condensate gas to flow into the wellbore 1. Then, start the conveying device 11 and open the outlet valve of the formation water tank 8. Maintain the value of the second pressure gauge 16 until the end of the experiment. As the condensate gas enters the wellbore 1, the pressure decreases, and the oil and gas phases in the condensate gas are separated. Combined with the formation water introduced from the formation water tank 8, the wellbore 1 is in a mixed state of oil, gas, and water. Step 4: Observe the waste oil tank 13. After the first drop of oil appears in the waste oil tank 13, record the time T1 at this moment. Then observe whether the frequency shift of the forward Brillouin scattered light recorded by the Brillouin optical time domain reflectometer 4 shows the frequency shift characteristics of the oil, gas, and water phases. If so, record the time T2 at this moment. The experiment is completed until all the condensate gas in the condensate gas tank 5 is discharged. After the experiment is completed, shut down the conveying device 11, and clean and dry the wellbore 1. Step 5: Utilize the optical frequency shift data measured in the Brillouin optical time domain reflectometer 4 and combine it with the previously established functional relationship between the Brillouin scattered light frequency shift and the densities of the three phases of oil, gas, and water to calculate the compositional changes of the three phases of oil, gas, and water from time T2 to the end of the experiment, and thus obtain the compositional change patterns of the three phases of oil, gas, and water in the wellbore 1 when the condensate gas reservoir encounters water invasion under simulated formation conditions.

[0035] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An experimental device for monitoring oil, gas and water components in a wellbore, characterized by: The invention comprises a wellbore, a single-mode laser, a polarization-maintaining optical fiber, a Brillouin optical time-domain reflectometer, a condensate gas tank, a pressurizing drive device, a formation water tank, a condensate oil tank, a natural gas tank, a conveying device, an oil-gas-water separator and a waste oil tank. The polarization-maintaining optical fiber is spirally wound outside the wellbore, the input end of the polarization-maintaining optical fiber is connected to the single-mode laser, and the output end of the polarization-maintaining optical fiber is connected to the Brillouin optical time-domain reflectometer; both ends of the wellbore are closed; the condensate gas tank is connected and communicated with the bottom of the wellbore, the condensate gas tank is used to contain condensate gas, and the pressurizing drive device is connected to the condensate gas tank for pressurizing the condensate gas. The pressure of the pressurized condensate gas is made higher than the dew point pressure of the condensate gas, and the pressurized condensate gas is driven to leave the condensate gas tank; the formation water tank, the condensate oil tank and the natural gas tank are all connected to and communicated with the bottom of the wellbore, and the formation water tank, the condensate oil tank and the natural gas tank are all connected to the conveying device, and the conveying device is used to convey the formation water in the formation water tank, the condensate oil in the condensate oil tank and the natural gas in the natural gas tank to the wellbore respectively, the oil-gas-water separator is connected to and communicated with the top of the wellbore, and the oil outlet of the oil-gas-water separator is connected to and communicated with the waste oil tank.

2. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 1, characterized in that: The top of the wellbore is provided with an oil nozzle, which is connected and communicated with the oil-gas-water separator.

3. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 2, characterized in that: It also includes a wastewater tank, the water outlet of the oil-gas-water separator is connected to and communicated with the wastewater tank, and the gas outlet of the oil-gas-water separator is communicated with the outside world.

4. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 1, characterized in that: It also includes a first pressure gauge and a second pressure gauge, wherein the first pressure gauge is connected to the condensate gas tank and is used to monitor the pressure in the condensate gas tank, and the second pressure gauge is connected to the formation water tank and is used to monitor the pressure in the formation water tank.

5. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 1, characterized in that: The pressurizing drive device includes a pressurizing piston and a piston drive device, the piston drive device is connected to the pressurizing piston, the pressurizing piston is arranged in the condensate gas tank, and the edge of the pressurizing piston is tightly fitted and slidably connected to the inner wall of the condensate gas tank.

6. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 1, characterized in that: The conveying device is a double-cylinder pump.

7. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 1, characterized in that: The polarization-maintaining optical fiber is fixedly adhered to the outside of the wellbore by adhesive.

8. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 1, characterized in that: The wellbore comprises a top cover, a barrel and a bottom cover, and both the top cover and the bottom cover are threadedly connected to the barrel.

9. The experimental device for monitoring oil, gas and water components in a wellbore according to claim 1, characterized in that: The condensate gas tank, the formation water tank, the condensate oil tank and the natural gas tank are all made of steel.

10. An experimental method using the experimental device for monitoring oil, gas and water components in a wellbore according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: calibrate the fluid density parameter range and forward Brillouin scattering light frequency shift parameter range of the oil, gas and water phases respectively; Calibrate formation water: Start the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the formation water tank, and then start the conveying device to convey the formation water in the formation water tank to the wellbore at a constant pressure. The laser light from the single-mode laser is transmitted to the wellbore by the polarization-maintaining optical fiber. The laser light with the generated scattering frequency shift is then received by the Brillouin optical time-domain reflectometer through the polarization-maintaining optical fiber. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer is combined with a formula to obtain primary formation water density data. Repeat the above test to obtain multiple formation water density data to determine the formation water density range, and establish a functional relationship between the Brillouin scattered light frequency shift and the formation water density. Calibrate condensate oil: Start the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the condensate oil tank, and then start the conveying device to convey the condensate oil in the condensate oil tank to the wellbore at a constant pressure. The laser light from the single-mode laser is transmitted to the wellbore by the polarization-maintaining optical fiber. The laser light with generated scattering frequency shift is then received by the Brillouin optical time-domain reflectometer through the polarization-maintaining optical fiber. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer is combined with a formula to obtain primary condensate oil density data. Repeat the above test to obtain multiple condensate oil density data, then determine the formation water density range, and establish a functional relationship between the Brillouin scattered light frequency shift and the condensate oil density. Calibration of natural gas: Activate the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the natural gas tank, and then activate the delivery device to deliver the natural gas in the natural gas tank to the wellbore at a constant pressure. Laser light from the single-mode laser is transmitted to the wellbore by the polarization-maintaining optical fiber. The laser light, after generating a scattering frequency shift, is then received by the Brillouin optical time-domain reflectometer through the polarization-maintaining optical fiber. The forward Brillouin scattered light frequency shift data measured by the Brillouin optical time-domain reflectometer is combined with a formula to obtain primary natural gas density data. Repeat the above test to obtain multiple natural gas density data to determine the formation water density range, and establish a functional relationship between the Brillouin scattered light frequency shift and natural gas density. Step 2: After obtaining the results of the oil, gas, and water three-phase calibration, the pressurizing drive device is turned on to pressurize the condensate gas in the condensate gas tank with the outlet closed, so that the pressure of the pressurized condensate gas is higher than the dew point pressure of the condensate gas; Step 3: Turn on the single-mode laser and the Brillouin optical time-domain reflectometer, open the outlet valve of the condensate gas tank, and allow the pressurized condensate gas to flow into the wellbore. Then, start the conveying device and open the outlet valve of the formation water tank to allow the formation water to flow into the wellbore at a constant pressure. Step 4: Observe the waste oil tank, record the time T1 when the first drop of oil appears in the waste oil tank, and then observe whether the frequency shift of the forward Brillouin scattered light recorded by the Brillouin optical time domain reflectometer shows the frequency shift characteristics of the oil, gas, and water phases. If so, record the time T2 of this moment. The experiment is terminated after all the condensate gas in the condensate gas tank is discharged. After the experiment is completed, the conveying device is shut down and the wellbore is cleaned and dried. Step 5: Calculate the compositional changes of the oil, gas, and water phases from time T2 to the end of the experiment using the optical frequency shift data measured in the Brillouin optical time-domain reflectometer in combination with the previously established functional relationship between the Brillouin scattered light frequency shift and the densities of the three phases of oil, gas, and water. This can provide the compositional changes of the oil, gas, and water phases in the wellbore when the condensate gas reservoir encounters water invasion under simulated formation conditions.

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